This program is a port of my GPS_LOG logging and navigation DOS program for glider pilots to the Windows CE platform. It runs on PocketPC (ARM, MIPS and SH3 processors) and PalmPC (MIPS and SH3 processors) devices. Program interfaces to any instrument that provides NMEA sentences for position, track, heading .... It also provides support for Borgelt B50 and other instruments. It was developed with a non-competitive glider pilot in mind, but can be used in any situation that GPS position data are available for logging. Current position, speed, track on ground, distance and course to a waypoint destination as well as needed altitude and other information are displayed in real time. A "moving, rotating map" display shows the path traveled as well as waypoints created in flight overlaid on a pre-generated map. A zoomed display mode designed for thermalling is useful for centering thermals, observing drift and estimating wind aloft. Wind can be also obtained automatically from circling and straight flight data. Needed altitude can be corrected for winds and glider polar. The program logs data in the IGC format, or it's own. It is also capable of replaying both formats for flight review.

A companion program for converting ESRI shapefile formatted maps to GPS_LOG WinCE maps is provided in the GPS_LOG Win32 (Windows PC) distribution package.


Users of GPS_LOG WinCE and associated software must accept this disclaimer of warranty. If you do not accept this disclaimer, do not use GPS_LOG WinCE.


This applies especially to any features of the program where estimates of factors that affect flight safety (like wind and required altitude estimates) are concerned. Such features are highly inaccurate and subject to many errors both human and instrumental.

GPS_LOG WinCE and associated software can be freely distributed and shared with others as long as no charges of any kind are made.

Programs in this package are free, but not in the public domain. (C) COPYRIGHT 1998-2001 by Henryk Birecki, All rights reserved.

CONTACT for sending comments, requests, bug reports : e-mail :


GPS_LOG WinCE.EXE    -  in-flight logging and display program.

GPS_LOGCEresDLL.dll  -  resource dynamic link library for above program.

GPS^LOGCEresDLL.dll  -  an optional language specific resource dynamic link library for above program. It takes precedence over GPS_LOGCEresDLL.dll

WAYPOINT.DTA   -  ASCII file containing set of waypoints that can  be selected for destination by the GPS_LOG user.  You can change this file in flight. In-flight generated waypoints are appended to this file, so you should keep a clean backup copy handy.

xxxyyyzz.MAP   -  ASCII files containing map information. The extension must be MAP. These files are modified by the program if you add waypoints in flight.

abcdefgh.PLR   -  file containing polar data for your glider. You have  to create your own. The one distributed here is valid for a DG100 at 30kg/m2 loading.

ALLSYMBL.MAP   -  a map you can load to see the symbols.

^GPS_LG#^.SLF - file with information on user definable symbols.

^GPS_LG#^.TCL - file with color information for track trace.

GPSLG!AT.WAV -file with sound to be played when entering turnpoint task observation zone.

GPSLG!TO.WAV -file with sound to be played when leaving turnpoint task observation zone.

GPSLG!LT.WAV -file with sound to be played to alert being in a restricted airspace.

GPSLG!SL.WAV -file with sound to be played to slow down.

GPSLG!FS.WAV -file with sound to be played to fly faster.

GPSLG!GW.WAV -file with sound to be played to remind one to extend gear.

City.bmp and building.bmp - user definable symbol examples

The file for logging navigational data can be placed anywhere you like, but keep the pathname to less than 49 characters.

All images in this document were generated from a desktop emulator program. Details of the appearance on your unit will vary.

Use of storage cards.

If you use a storage card for your maps, waypoint, polar.... files and GPS_LOG WinCE does not see them, create a "\My Documents" folder on the storage card and put files in it. This is a Microsoft limitation. This may not be necessary on some newer devices. Microsoft also puts limitations on number of directory levels in storage hierarchy, so you may have to "flatten" your directories tree to do that.


Some Windows CE PCs, like the Compaq Aero, may have a feature that allows you to close all/active tasks. Executing this command while GPS_LOG WinCE is running locks up the unit on Compaq Aero and it has to be ”hard reset”. I do not know how other units will behave. Always exit GPS_LOG WinCE from the program menu. If the program is hidden, then run it again. Only one instance of the program is run at any time (even on older machines).

This program was designed around using Arial font. It will work fine with other True Type fonts. Some (especially older) WindowsCE units do not support True Type. What you will get will depend on manufacturer's implementation and variety of font sizes you have on your unit. I will not try to fix it.

All efforts have been done to make this program bug free. However there are features in it that are at best experimental, and there may be some bugs. The use of NMEA compass heading sentences for wind determination has been tested on idealized data. The computations are working properly, but are very sensitive to compass input. Compass errors of more than 2 degrees make these computations pretty useless. Similar caveat applies to calculations involving true air speed. The only instruments currently supported that provide it are Borgelt B50 and Cambridge 302 digital variometer. 

If you notice any bugs, please contact me, so that they can be fixed for everyone.

GPS_LOG WinCE Description

Pocket PC (Windows CE 3.0 and above) version removes the task bar visible on top of this picture to enlarge map area.

Track (magnetic) and altitude MSL (or IAS or Speed to fly)

Destination “:” indicates no wind corrections.
Distance, bearing, needed altitude
If team position reporting is enabled, position can be displayed in an alternative format. You can communicate encoded information shown in this display to your team mates. Spaces are just for readability.
Currently used wind (true), S-straight and level (C- circling, T-turning)

Destination, “>” indicates wind corrections (":" otherwise).
Distance, needed heading change to Right, needed altitude
Track (true) and speed to fly, "I: ..." - indicated air speed ,"T: .. " - average climb rate in thermals (recommended MacCready setting), "S:..." - zero MacCready horizontal air motion only speed to fly, "G:...." - altitude AGL, "D:..." - flown distance estimate, "fl:....." - flight level (altimeter setting corrected pressure altitude /100). Map symbol note.
Indicated airspeed ("I: ..." string) displays GPS derived ground speed corrected for altitude. In absence of wind it should be the same as the value shown by airspeed indicator. The difference will give indication of head wind "component".

NOTE: if meters are used to display altitudes 'g' replaces 'm' as magnetic direction indicator.

You toggle between various displays by double clicking (or clicking – configurable option) at appropriate places on the display). If compass sentences are available, you can toggle track direction into compass heading denoted with letter "h". You can also have some control over what parameters are shown.

GPS-LOG WinCE.EXE uses COM1: to connect to the GPS. It connects at the standard 4800 baud. These parameters can be preset by setting options from within program.  It accepts seven  kinds of standard NMEA sentences RMC, GLL, GGA, VTG, and HDM, HDT and HDG (magnetic compass heading), as well as the Garmin proprietary RMZ sentence. You can switch between RMC, GLL-VTG, and GGA-VTG combinations for position and speed data from within the program.

Note: If you attempt to use this program with a GPS in a "simulator" mode, you may not get anything. Some (not all) GPS units transmit NMEA sentences tagged as invalid in that mode. Invalid sentences are ignored by this program.

I developed this program with a Garmin 12XL. If you have problems with a different kind of a GPS unit please set the program to record all sentences in it's raw form. In order to save raw data check the “raw data” box on the logging options (this is the only option not remembered across sessions). This will generate (or append to) the “\My Documents\GPS_LOG WinCE\rawGPS_LOGdata##!!.txt” file all characters that come on the serial port. Send me that file and I'll try to get it working for you.


Many of the devices for which this program is designed sport four buttons (so called program buttons) on the front. These buttons can be mapped onto various actions of the program facilitating user interface. 

However, in some cases (e.g. selection of a landing site) you may expect the following button behaviour:

Button action can also be activated via RS232 communication port.

Hardware arrow keys can be mapped to perform functions as well. While a note window is displayed the up and down arrow keys scroll the note window.

These devices also should have an "Action Button". Usually it is combined with the arrow controls into a wheel. Pushing the wheel in results in pressing the Action Button. GPS_LOG WinCE uses the Action button to activate parameter setting window.

Hardware button functionality is not included in the Win32 PC version of the program.


GPS_LOG WinCE program displays path flown, and a blinking cursor at the current position on top of a user defined map. Cursor in shape of an arrow indicates approximate direction of travel. As current position approaches an edge of the map, the map jumps to bring the cursor to the center of the screen. You can change the threshold for the map jump by setting map margin in the options. The larger the threshold value the closer to the center of the map jumps occur. After map moves, the flight trace is refreshed from cached data. The cursor is not visible during refresh. Arrow cursor can be replaced by a user defined shape. Default arrow cursor changes every 45 degrees. Using user defined shapes one can have cursor changing more often.

On color capable (8 bits per pixel or more) units flight trace indicates lift or sink by color. You can control colors displayed by modifying the ^GPS_LG#^.TCL file included in distribution. To have a black trace set all numbers in the file to zero. If this file is missing program will use it's own default set which is different from that in the distributed file.

When the cursor is within bounds of the visible map section, the map will rotate to keep the current track over ground pointing up. The rotation will only happen if the rate of turn is smaller than the turn tolerance set on the compass tab of the options, and the track changed by more than the minimum angle set on the maps tab of the options. This automatic rotation depends on track information being supplied by the GPS unit, or having been recorded to file. The "Flip Map" button displays the icon while rotation is enabled. It can be suppressed permanently by clearing the "Rotate to TOG" checkbox in the maps option tab ( icon on the button). It can also be suppressed (North on top of the map) temporarily by clicking on the "Flip Map" button ( icon on the button). Clicking the button again will re-enable rotation. While the "Rotate to TOG" checkbox is cleared, the "Flip Map" button rotates the map by 180 degrees. Symbols and their legends do not rotate.

When autorotation is enabled and map margins are set to less than 25%, plane position is re-centered to about 1/3 of the map height, giving more "forward visibility".

You can move the map on the screen to review its appearance or to view cached flight track by using the arrow keys. You can also drag map image with your stylus. If you do this during flight, the automatic map move is suppressed until you bring the cursor back within map margins.

Locations on the map are shown by a variety of symbols and lines with legends. The program uses 16 predefined symbols that you can use on any predefined map. In-flight generated waypoints are shown with symbols as on the right side of the above picture. The default symbol used for symbols that cannot be located is shown on the picture as #18. Symbols #16 and #17 are user defined and contained in the program distribution files. You can generate your own symbols as outlined below.

Course Line

You can display course line on the screen. Course line is determined by destination and your location when destination was changed. You control whether program shows the course line or not on maps tab of options. Course line is not shown when a task is displayed on the screen unless a checkbox is set in task options. It is displayed as 2 pixel wide black or dark blue line. As you change your destinations there is a slight delay before course line appears. That is to allow you rapid toggling through destinations.

Support for VGA screens and screen rotation

PocketPC 2003 introduced ability to rotate display and some of the devices are equipped with VGA screens. GPS_LOG WinCE provides support for these features. As the program is designed to operate in portrait mode. It makes certain that display is rotated to that orientation when starting and rotates screen back to the original orientation at exit. User can set how much of the VGA resolution is used for drawing maps in the Display options.

Companion programs for converting ESRI shapefile and ERC/Info (E00) formatted maps to GPS_LOG WinCE maps are provided in the GPS_LOG Win32 (Windows PC) distribution package.

Unicode support

Except for need to satisfy IGC mandates for log files and logger data, GPS_LOG WinCE is a fully Unicode aware program. This means that you can enter names in any language and have them displayed in appropriate script. The only requirement is that you have fonts on your system that support the language. On a PC, Arial Unicode MS font covers pretty much the whole range. Its file size of over 22MB is at this point probably prohibitive for use on a PDA, but in most cases one does not need to be able to cover all languages at the same time. Here is how couple of screens may look with Japanese information.

Files that GPS_LOG WinXX  creates or does not know how to classify are treated as UTF8 encoded files. Unfortunately, some older PDAs like Compaq Aero 1550 may not support UTF8 encoding. In that case such files are treated as standard ASCII files. If the program encounters a comment “;ASC” (no quotes) at the very beginning of a file, it interprets the file to be ASCII.

Font support

Some WindowsCE devices support font linking. That is a program may be using a font (base font), but if system does not find a character representation in it, linked font will be searched for the character. This would apply to all programs on that device as long as they were using the same base font. In addition one can specify which characters should be taken from linked font even if they exist in the base font. Distribution package of GPS_LOG WinCE (OS3 and higher) includes a utility called FontLinker that you can use to set up such association on your device. Base fonts are ANSI fonts, Linked fonts are all others. Program cannot help you with the file name of a linked font unless it is already linked to some font. You specify replaced characters using hexadecimal notation with four "digits" each. You can specify a range as in the example on the left. Example on the left shows standard replaced characters that would be used on Japanese or Chinese machines. For Korean only character 005c is replaced. Note that replacing character 005c (decimal 92, '\') is not advisable. It would replace reverse slash used in file names and other places by Yen currency mark.

To set up linking, fill out the appropriate data and click Link button. This will transfer data to device registry after some (possibly insufficient) validity checks. Font linking will not become active until you do a soft reset of the device. This is when system reads the registry data. Font linking worked for me on two PocketPC 2003 devices, but did not on an OS3 device I tried it on.


Clicking on the "Select Destinations" button produces a list of waypoints that you can chose the destination from. This list is stored in a selectable waypoint file (see format below). You can also select a destination by clicking on a map symbol that has altitude information. When selecting a turnpoint for a task, an additional checkbox will appear to let you designate that turnpoint to be a checkpoint. Checkpoints show up as turnpoints on maps and are treated as turnpoints for navigation, but are not declared to file, nor to a FAI certified logger (unless that logger supports checkpoints).

Field elevation, distance, and course data followed by any existing notes are displayed for the selected destination.  Note that field elevation may be obtained from elevation data if it was not specified in waypoint file.

Waypoint selected in the list can be edited after clicking on the "Edit" button. 

You can delete a waypoint by editing it and setting the first character of its name to ";".  This method is useful primarily to delete accidentally dropped waypoints.

You can change the file containing the waypoints. The last file is remembered and used as default the next time you start the program

Program remembers up to fifteen destinations that you selected. Once you select more destinations the newly selected one replaces the oldest one. You can toggle between them by double clicking  on the destination name display. On the right moves you forward, on the left moves you back.

You can access this dialog even if no GPS data were received. In that case the distance to the waypoint (175.2M in the picture) and bearing are calculated from the program default position. When accessing this dialog hardware buttons can be used as described above.

Pressing the “drop Waypoint button” selects the current position to be a destination waypoint, and adds it to the waypoint file with a name "Waypoint x" where x is a consecutive number if Save Dropped Waypoints box is selected on the logging options tab. Dropped waypoint is also marked on current map using a small square with a digit or a letter, and corresponding symbol is saved to the map file.  You should edit the waypoint file at a later time to name the waypoint and provide correct altitude. You should also edit the map file. This can be accomplished while the program is running using the "Edit" button for waypoint editing, and the "Edit dropped" menu item to modify map symbols. Dropped waypoints are "stamped" with date and time as a waypoint name in a waypoint file, but not in a map file. Time and date information comes from computer, but is in UTC, not local time. If digital elevation data are available, dropped waypoint is saved with ground elevation rather than current altitude. Waypoint "stamp" contains 'GL' if digital elevation data are used.


Clicking the “Select a Landing site"  button will give you only the few closest landout sites sorted by altitude needed to reach each site (field elevation, distance, and course  data are displayed during selection). You must have acquired the first position data point for  this key to become active, and you must have marked landout sites in the Waypoint.dta file (or another one that you are using) with "^" as the first character of waypoint name to get any. You will get up to 16 sites if they are reachable, 8 if 8 or fewer are reachable.

Needed altitude is shown in the beginning of each line (units are omitted. It is computed taking wind and polar as directed by the options in effect at the time and speed that gives longest distance flown.

When accessing this dialog hardware buttons can be used as described above.



Use “Setup | Add …” buttons to access these dialogs. You can also access the Add Waypoint dialog by clicking on the [New] button on Select Destination dialog. Note that you do not prepend the “\” character to the name to generate comments, just fill in the Note box. The same applies for the “^” landout character. For the map symbol fill in the name with all the information required (circle information, legend, show symbol information, arc or line information). Do not enter anything in the Note box for arcs and lines. See the Map File Format section for additional information.

The "New File" button on the Add Waypoint dialog allows you to change the waypoint file. It’s implementation allows you start a new file, so you will get an overwrite warning if you select an already existing file. Unfortunately WinCE devices have a rather poor file dialog that allows you to type-in a new file name, so unless this is what you want to do, use the File menu to change the waypoint file (or the “W folder” button).

The "From File" button on the Add Map Symbol dialog allows you to import a waypoint into the dialog. Waypoint name will be truncated to first six characters. You of course have to add all the necessary "adornments". 

If symbol number is set to -4 (arc definition), program will fill in the name field with a template for arc definition. It will also change the "Name" label to "CCW Arc". CCW stands for counter-clock wise. The same will happen for symbol -6 (arc included in a polygon)

While symbol number is set to -2, an additional control with shows up with the polygon fill color number. When that number is set to anything else than 0 (no fill) a color sample appears.

The Add Symbol dialogue is also used to edit dropped symbols ("Edit Dropped" on "Action" menu). Setting the first character of the symbol name (legend) to semicolon (";") deletes the symbol from a map. If you do not want to change a given dropped symbol, click on "Cancel" and the next dropped symbol will be shown.

You cannot add "dropped" symbols. You can only edit them. You can change it's symbol to another "dropped" value, but be aware that edited symbol is placed at the end of a file, so you will be asked to edit it again (just click [Cancel] when the time comes).

Symbols defined with numbers greater than zero and text symbols (-5) are displayed immediately after definition (including associated circles). Other symbols added using this dialog are not. You need to set the map file from file menu to see them. Do that after you have added all symbols you need. You cannot add symbols to binary map image files.

If decimal minutes are selected in Miscellaneous options they also show up decimal when editing waypoints and dropped symbols.

For waypoints you enter altitude in feet or meters depending on current units. This entry is saved in the same units to waypoint file.

In order to associate sounds and images with waypoints enter the file information in the Notes edit window. Start a line with '#' followed by 'i' for image, or 's' for sound and follow that with file name without any preceding spaces. If the file name starts with '\' it can refer to any storage location. Otherwise it is relative to the directory containing the GPSLG!LT.WAV zone alert sound. File information has to follow a note if there is a note. So for Eagles Roost information as in the picture above the Notes window may look as follows:

Not too friendly, but landable

Trick: When adding a waypoint you can specify altitude of less than -1000. If you do that the program will ask you if you want to set the default location (location that it wakes up in). The change does not take effect till you restart the program.

If you specify waypoint altitude to be -1, program will ask you if you want to change an undefined altitude. If you answer "No", program will attempt to find correct altitude in digital elevation data and add note "DEM Alt." to the waypoint if successful. Otherwise it will return to waypoint editor.

If you want a waypoint to be displayed on a map as a symbol you should follow the name of a waypoint by coma symbol number and optionally by  coma delimited minimum and maximum map scales for visibility of that symbol, e.g.:

Eagles Roost,3,10,130 

Space after first coma is not required here. If you want this waypoint to be selectable on a map even if it is not landable, replace coma after symbol number with "^", e.g.:

Mnt. Rose,11^10,900  or Mnt. Rose,11^


Turnpoint, task and map file formats allow for notes. If there is a note attached to destination, it is displayed while selecting the destination and can be displayed on the main screen by pressing on the destination name for about a second. You need to click on the displayed note to make it disappear. Clicking on a map symbol, which has a note attached to it, makes the note appear.

While a note window is displayed the up and down arrow keys scroll the note window. This is also true for notes from alarmed zones.


In addition to notes, waypoints can be associated with images and sounds. Currently windows bitmap (bmp) format is supported for images. Computers with WindowsCE  3.0 can also display jpegs (jpg). If you press on destination name in navigation display for about a second, three things may happen depending on what information is attached to a waypoint. A note box with a note may appear, a window showing an associated image may appear and an associated sound may be played. Both the note and image windows can be cleared by clicking on them. Associated sound is played also if the destination changes to one with an associated sound. See details of waypoint file format or section on adding and editing waypoints for details on how to associate sounds and images with a waypoint.


Program remembers up to 15 destinations that you selected. Once you select more destinations the newly selected one replaces the oldest one. You can toggle between them by double clicking  on the destination name display. On the right moves you forward, on the left moves you back. The maximum number of  destinations (up to 15) that can be saved to the queue is controlled by an option in the miscellaneous tab. If you press and hold on the name of a destination for about a second, a note will be displayed if it is associated with the waypoint in turnpoint file.

While a task is active, selecting a new destination does not replace destinations that are part of a task. If a destination needs to be replaced, oldest destination that does not belong to task is replaced (it could be the landing destination of a task). If the task occupies all available locations the "oldest" task destination is replaced. This is usually the start of a task.

Selecting the "Show to Finish" option in "Altitude modes" forces the destination displayed to be the finish site of a task. You cannot associate notes with task points.

Double clicking "To:" changes it to "To>" and vice versa. The ">" means that you are requesting wind corrections for needed altitude and heading. The required heading is either given as absolute magnetic bearing, or if you request wind correction, and valid wind was calculated, heading is displayed as required left and right corrections indicated by letters "L" or "R".

If you are within an auto-detect circle set up in Altitude modes "At" will be displayed instead of "To". If the destination is a task point with an observation zone, the observation zone is used to determine whether to display "At" or "To". 


In order to enable sound indicators for entering and leaving observation zones associated with a task you have to set Auto-detect in  Altitude modes dialog. When a task observation zone is entered a sound defined by a GPSLG!AT.WAV file is played and when a zone is exited GPSLG!TO.WAV file defined sound is played. The exception to that rule is that when displaying needed altitude to task finish only the "At" sound is played for the last turnpoint before finish. If one sound starts playing and does not finish before the next one is required, the second one is skipped. Map file format supports restricted airspace definitions. Upon entering a restricted zone an alert sound defined by GPSLG!LT.WAV file is played and an [Alarm] indicator button shows up on screen. 

The [Alarm] indicator button stays on the screen till you leave the restricted zone that triggered it. Clicking it makes it go away for a very short time it then reappears recalling the associated restricted zone note. Holding the [Alarm] button down for about two seconds makes it go away till next time you enter the zone or until the next time you re-read the map depending on setting in SUA alarm options.

You have an option to turn on speed commander which plays GPSLG!SL.WAV sound file when you are flying faster than computed speed to fly and the GPSLG!FS.WAV file if the program thinks you are flying too slow. Computed speed to fly is based on the averaged sink rate, polar, and MacCready setting. Sounds are not played while you are circling and are played more often if the speed error is larger.

You also have an option to have the program warn you to extend your landing gear. Program uses the GPSLG!GW.WAV sound file. It plays it three times in intervals as you descend through AGL altitude defined in Miscellaneous2 options. Set the threshold altitude negative to disable the warning.

Sound files should be located in "\My Documents\GPS_LOG WinCE" or "\My Documents" folders. You can use any sounds you wish as long as the wave files are named appropriately. Make certain that your computer has sounds enabled for programs, and that system volume is set to adequate level.

If you see asterixes "*" in the displayed time or position data it means that the data is outdated (either GPS unit sent you data with time not updated, or it has been a "long" time since it sent any position data at all).  At the same time as "*" appears, a "No GPS" annunciator appears in top left corner of the map window. You can click it off, or it will disappear next time GPS data comes on the communication port (but see also NMEA interface options).

If data are not recorded in a log file a black stripe is displayed between the "Flip map" and "Expand map" buttons on the left hand of the screen.


You can toggle between  display of current altitude, estimated indicated airspeed (ground speed corrected for altitude) [ I: ], recommended speed to fly for 0 Mac Cready setting in zero vertical speed airmass corrected for wind [S>],  and recommended speed to fly [F>] by (double) clicking on their image. Speed to fly is based on currently selected polar, the average vertical speed and Mac Cready setting and is corrected for wind.   Indicated airspeed is obtained directly from Borgelt B50 if available. If Cambridge 302 is available, indicated airspeed is derived from provided true air speed by correcting for altitude. If wind data are not available you will see "F:" or "S:"


The time logged to file is the same as the one displayed on the screen. In the standard logging format, it is logged in decimal format for ease of use with spreadsheet programs where one might want to plot data versus time. For the same reason the logged time does not start over from zero as one passes midnight but keeps on going with added multiples of 24 hours. 

Clicking on the elapsed time toggles between time elapsed from the time the program started to a stopwatch time (starting from 0). If you want to do a hard reset of the stopwatch to zero then use the "Reset Clock" entry on the "Setup" menu.


GPS_LOG WinCE can display altitude above ground at a given position provided that you supply appropriate data. The data take form of two files: a header file with extension of "hdr" and data file with extension of "bin". These files conform to format of GLOBE project and can be obtained at You should get data in the freeND format for a PC. In addition a more accurate set of data is available from Shuttle Radar Topography Mission ( )  at You need the DEM and HDR archives. These downloadable files are large and with fixed boundaries. They have extensions of *.dem or *.hgt. You should use the DEMtoMAP.exe utility that comes with the PC version of this program to create files of appropriate geographic content and size. You choose the appropriate set using the "AGL file..." entry from the file menu of the program.

Data from above sources are based on about 1km grid. They are not going to prevent you from crashing into a mountain slope if you trust their accuracy in a mountainous region, or around small hills. Use them with CAUTION!!!

The AGL altitude information is used to generate alarms for restricted airspaces and to create background maps.

If you try to open an AGL file, select a *.hdr file and  get an error message saying "Cannot open AGL data file": Open the hdr file with text editor. Check first line. It should read "file_title = filename" Program looks for filename.bin data file. If you got your data from NOOA without specifying file name, you probably have "My Selection" as filename, but you named your bin file otherwise.

The digital elevation data files are used extensively in the program You can put them on a storage card, but for sake of performance they should be located in the main memory of a PDA.

Maps based on Digital Elevation Data

Program can create background topographic maps based on the digital elevation data used fog AGL display. This feature is enabled in maps options.

Map is created with 256 altitude isolines. The default spacing between them is 66 feet (20m). There is a file GPS_LG_ECL.ECL that contains color mapping information (if it is not there, the default colors are used). You can edit it. You do not  have to have all 256 points, just create a file with altitude values of  interest (they do have to be in ascending order). Format is : altitude(in feet), red,  green, blue CRLF (carriage return line feed) (colors are 0-255). You can also change the default spacing between isolines. In order to do that include "step x CRLF" as the first line in the file. x is the altitude step in feet (integer). The GPS_LG_ECL.ECL could look like below.

step 10
0 0 240 255
10 70 255 0
20 100 255 0
40 142 255 0
80 200 255 0
140 255 245 0
200 255 193 0
300 255 121 0
400 255 61 0
950 255 27 0
1500 255 15 0
2100 255 13 0


Clicking on "Competition" in setup menu starts a sequence of events that prepare for task recording as per IGC regulations for competitions and badges. You start by defining a task. You need at least four points: takeoff, start, finish and landing sites(in that order). Turnpoints go between start and finish. Use the [Save As] function in task definition for easy recall of task for future declaration. The [Declare Competition Task] will not show up. It is not necessary as declaration is made as part of the competition setup process. After you are done, the header definition dialog comes up. Additional headers can be defined by choosing the right one in the header selector (window with  "GPS"). 

Choosing the "SEC" header brings up two windows to enter two copies of official observer security phrase. This is encoded into the file for verification purposes. Security phrase has to be at least 8 characters long (or none), and cannot end in spaces nor tabs (they are quietly stripped). You can only use ASCII like characters in these windows. If you try using other Unicode characters, you may not be able to verify passphrase later. If you cannot generate ASCII letters use digits 0-9.

Most (but not all entries) such as pilot name, competition class... can be entered to and selected from lists that are remembered. In order to enter an item into list, type it into appropriate box and click {Enter] on the keyboard. Program will ask you to confirm addition. To delete an entry from a list, select it and click [Ctrl] followed by [back space] on keyboard. Program again will ask or confirmation. If there are entries that are not on lists when you click OK, program will ask you if you want to add them to lists.

When written to IGC file, information you enter may be modified. FAI IGC specification demands that only "printable" ASCII characters can be included, and some characters (like coma) are reserved. GPS_LOG attempts to map characters like äüö...  to auo... and replaces reserved characters by spaces. If GPS_LOG does not know what to map to, it substitutes "?" for the character. 

After you are done with this, you need to select a file for logging. IGC format is enforced and you should not change the suggested name. Since on some older machines suggested file name does not show up in a file dialog, an "L" (logbook) record is added to log file indicating preferred file name. You may want to change file name later if appropriate. This record is not subject to security measures. If you are declaring the task to a FAI logger (such as EW, or Volkslogger) you can cancel the file selection dialog and still proceed. In this case any file logging of NMEA data will be terminated. You can turn it on later from file menu.

Once everything is ready, the program displays a wait dialog, that allows you to either start logging, or change the task. Again use the [Save As] function in task definition for easy recall of task for future declaration. [Declare Competition Task] does not show up since declaration is made as part of the competition setup process. The last declared (created) task counts. Once  logging starts, you can still generate a new task or recall one of previously saved and declare it. 

While logging, program generates security information that is saved in G record to file when you exit the program or change log file. Use the attached VALIGPSL.EXE (Windows PC program) to verify recorded file if needed. 

Note: This program generates a "serial number" required by IGC by inspecting the owner information on the device. This serial number is not guaranteed to be unique. The security measures employed  are not extremely strong, and I make no representation that any of this meets IGC, SSA or any other body's requirements. They should be however fully adequate for reasonable people.

In addition to header records, GPS_LOG WinCE can generate event records (E records) in an IGC file. Events are mapped onto RS232 port status lines, which can be hooked up to monitoring switches. Typical applications would be "Engine up/down" or "Engine on/off", "Pilot event", "Start", "Finish" events.


While flying a task GPS_LOG WinCE can provide relevant distance, speed and time information for task and current task leg. To display task information click through coordinates and time display till you see something like the picture below.

Line starting with "T:" shows distance flown on task so far and speed achieved from start. Time shown on the right is estimated time from current time to finish in hours and minutes.
In order to see leg relevant information, click through variometer, wind and track information till you see a line starting with "L:" This shows distance from last turnpoint , speed achieved on current task leg and estimated time to complete this task leg. This will also cause task information to be displayed.
Clicking on estimated remaining task flight time  shows you abbreviated task distance that would be credited if you skipped the rest of turnpoints and reached finish.

Clicking on abbreviated task distance  shows you estimated arrival time in local time and 24 hr format. This depends on your PDA being set to proper time. Clicking estimated time of arrival brings you back to display of remaining task time.

Clicking on the achieved task speed toggles it to displaying predicted task distance and vice versa.  This may be of importance for Turn Area Tasks. Once one enters a turnpoint observation zone, the predicted task distance will reflect task distance assuming one immediately starts flying towards next turnpoint.

Task distances shown in these displays are computed based not on declared turnpoint, but first points after start and finish, and points on the track within turnpoint observation zones that maximise task distance. Time to finish is estimated based on current MacCready setting and wind information. It assumes that one flies at MacCready recommended speed to fly through airmass with no vertical motion throughout the flight to finish.

While one is flying within a turnpoint observation zone estimated time remaining on task is computed assuming that one is already heading for next turnpoint. This is significant in cases when one is flying through a large turn area. Upon entering such an area one will usually see a precipitous drop in the estimated needed time. As long as one is flying towards the turnpoint of a zone one is flying through, one should expect the leg distance to remain zero as the point that maximises task distance is moving. Distance flown on task reflects the distance flown towards (and away from) that turnpoint. Another thing to remember about leg distance is that it is measured from last turnpoint that is not a checkpoint. Thus it is quite likely that after passing a checkpoint one sees decrease in leg and task distances flown.

If you happen to miss passing through observation zone of a task checkpoint, computation of estimated time will give false results until you pass through observation zone of a turnpoint that is not a checkpoint.

EVENTS and RS232 port driven buttons

Warning : This feature depends on hardware implementation by manufacturer of handheld device. It may not work completely as described on all units. For the specific case of Compaq Aero 1550 see at the end of this section.

RS232 port has 4 status lines that can be used as inputs to the handheld device. These are "Clear to send", "Data set ready", "Ring indicator", and "Receive line carrier detect". The other two status lines "Request to send" and "Data terminal ready" are outputs that are set high by the program. You can use the output lines as voltage sources and wire the four input lines through switches. Changes on the input lines can be translated according to map established in the Settings | Events tab. 

If a "BtnX" entry is selected in this options tab, "RS232 Keys" tab similar to Hardware button X tab appears next time Setup|Options is selected. This tab allows you to select an action executed when corresponding RS232 line goes high. 

Selecting any of the events results in a corresponding event "E record" being recorded to IGC log file when the line goes high. For EON (EUP) event a corresponding EOF (EDN) events are recorded when the line goes low. Events are recorded only after GPS acquires signal and program receives its data.

If event map is changed after GPS acquires signal, a PEV event is recorded to IGC file. This event contains information on previous and new mapping.

Selecting the "Invert" checkbox results in switching the "goes low" and "goes high" meaning for all lines.

On a female 9-pin RS232 modem connector, above signals are usually assigned to following pins:
inputs  : CTS - 7, DSR - 4, RING - 9, RLSD - 1
outputs: DTR - 6, RTS - 8
ground - 5.

Compaq Aero 1550: In this case the RING and RLSD signals do not generate events, furthermore RLSD is set high by the unit and should not be pulled down. Generating DSR signal results in the RING event being triggered as well. Thus RING and RLSD events should be set to "None".  


This display shows instantaneous vertical speed, averaged vertical speed and Mac Cready setting to be used for speed to fly. When vertical speed is derived from GPS data, total energy compensation is not applied and  is not very reliable. The averaging time is set in the options, and should be set long to make the average useful. Speed to fly computations use the average. Mac Cready value is in the same units as vertical speed. If no external source (e.g. B50 vario) for it's value is available, you can set it using the up-down control next to it. You can also set it from Mac Cready display of needed altitude. Otherwise the up-down control is replaced by letter 'B'. 

Display of vertical motion may be different if Cambridge 300 series or Westerboer VW921 instrument is present.

If automatic setting of Mac Cready value is allowed, it is followed by an 'a'. (double) Clicking the Mac Cready value toggles between manual and automatic setting. Automatic setting is derived from previous thermals (see Thermalling tab of options). Only thermals with three or more circles are considered. You can also see the (average climb rate in thermals) recommended MacCready value next to the track information with "T:" in front of it.

When circling it is possible to display average climb rate in a thermal by setting an option in the "Thermals" tab. The vario display assumes form of:

Vz: 3.2 [2.4] kts

in the example above [2.4] is the average climb in the thermal and 3.2 is the average climb rate previously displayed as <3.2>. In most cases the average climb rate will be close to the climb rate averaged over the last circle.


The program can determine winds in a variety of ways. See the description of winds tab of options for the appropriate settings. 

In 'Track-Manual' mode double clicking on display of wind while the program is in thermalling mode results in wind data being substituted by data derived from variation of ground speed as you go around the circle. This is probably he most accurate way to determine wind using this program. The main sources of error in that case are your ability to keep the indicated speed constant and rotation of the thermal.

In 'Track-Auto' mode, wind is determined automatically while you circle. You do not need to double click the display. However you should set a number of initial circles in the thermalling tab of options to something reasonable, so that your air speed has time to stabilize.

In 'Compass' mode wind is determined from the compass and GPS NMEA sentences. Determination is done from 'straight and level' flight. Two consecutive data sets are need at two distinct headings. Click on Reset  in the “Winds” dialog. to reset computations. 

In 'Air Speed' mode wind is determined from true air speed and GPS NMEA sentences. Three consecutive data sets are need at three distinct headings. Click on Reset  in the “Winds” dialog. to reset computations. This mode switches Track-Auto mode while circling. It is supported for instruments that output TAS such as Borgelt B50 or IAS such as LX-160. In case of instruments that provide IAS ,but not TAS, IAS is corrected for altitude to obtain TAS. This correction is not perfect and may introduce errors in wind computation.

In 'All three' mode wind is determined from GPS, compass and true air speed NMEA sentences.

In 'Instrument' mode wind is determined by an external unit like Cambridge 302 digital variometer.
You can also set wind in the “Winds” dialog. In order to set a desired value, enter speed and direction. Winds set in that manner do not get added to the list. he list box displays past history of determined winds. Newest on top. Clicking on any of the entries in the list box fills in the edit boxes with information.


Currently used wind is displayed as one of the display options. By (double) clicking on displayed wind values you can change currently used wind to other values that were stored. Clicking on the left gets you newer values, on the right earlier values. The selection does not wrap, so if you reach the end values do not change. This is useful if for some reason you think the latest value is erroneous.
Wind direction is also displayed as an arrow icon on the left of the map under other buttons. This is only available on the PC and OS 3.0 and higher Windows CE versions. Arrow shows wind flow direction relative to map orientation. Note that the wind direction value in the numerical field above is the usual FROM value, while the arrow depicting flow points into the TO direction. Arrow is shown on a colored field which is green for wind speeds less than 8knots (15km/h), red for speeds greater than 19 knots (35km/h) and yellow in between. For grey scale displays equivalent colors are grey, black and white.


At startup the program suggests a name of the data logging file. This does not seem to work for the WindowsCE 2 version. The suggested name is of the form YYMMDD-X.GPS (year month day - consecutive number) for native format data. The name suggested for IGC formatted data adheres to IGC specifications.

If log interval is set to zero in Logging options, program will not ask for log file name at startup and a log file will not be created. If you change log interval from zero to another value while logging is not in progress you will be asked for a log file name.

You can choose standard or IGC format in the “Logging” tab of the options. This controls only the default extension and suggested file name. Selecting extension in open file dialog overrides the default, but does not change the suggested name till next time.

The standard data logging format is a simple comma delimited one. It is designed for ease of use with popular spreadsheet programs for data analysis, sorting ... The minimal set of data saved is time, location and altitude. By checking the "Log All Types" checkbox on the logging options tab you can also log speed, track over ground (magnetic and true), compass heading and true air speed if available. Altitude logged in this format is the GPS reported one, not the pressure altitude.

Different formats should not be mixed in the same file when appending data. Otherwise unpredictable results may occur when retrieving data.

When logging data in IGC format program adds information headers about pilot, glider, standard GPS fix accuracy, GPS and pressure data sources. This information needs to be supplied once, and if it changes, by going through the competition setup process. Standard GPS fix accuracy defaults to 10 m. This value is used to report fix accuracy in B records by taking into account horizontal dilution of GPS signal. Satellite configuration is reported in F records.

Logging frequency is controlled in the logging options, however all positions are logged while proximity to a turnpoint is detected, or position is within observation zone of a task turnpoint ("At" indication in destination display).

If data are not recorded in a log file a black stripe is displayed between the "Flip map" and "Expand map" buttons on the left hand of the screen.

Engine Noise Level LOGGING:

GPS_LOG WinCE is capable of using computer microphone to record noise level in IGC log file. At this point this is an experimental function and is not enabled by default. In order to enable it you have to create a file in "My Documents" folder on your computer. This file has to be named "ENLset.txt" and is a simple one line ASCII (not Unicode) text file. A default file is distributed in installer packages, but it is not installed. You can create it easily using Notepad or other text editor on your PC. It has to contain two or three numbers separated by a coma, e.g.: 100, 1, 2  There should be no space between first number and the coma. First number represents the bandwidth of low pass sound filter (100 corresponds to 10ms relaxation time), the second number should be 0 or 1 and it controls how fast the filter rolls off (1 gives steeper filter). These values are recorded to IGC file, though bandwidth is represented by relaxation time in units of 100 microseconds. The third number determines if program attempts to re-start sound recording if it gets hanged up. If it is missing or less than one, no re-start is allowed. If it is greater than zero then it is the number of re-starts program will attempt.

In order for recording to work properly you should disable automatic gain control of your microphone if there is one. Look for it in Settings | System | Audio or a similar place on your computer.

Known issues with noise level logging:


The program is capable of replaying flights from data stored in IGC formatted and GPS_LOG formatted data files. Click on "Replay File..." in the file menu and select a file to replay. An arrow button will appear in the gray region to the left of the map, and the menu item will change to "Stop Replay File...". While you press on the arrow button and hold it down, the file will be read, and data interpreted as if coming from the NMEA source. Release the button in order to pause replay. All other buttons and functions should work as if in flight except that the data are not logged. Before logging new data, you should exit and restart the program. 

Trick: If you press the arrow button and then move the stylus off it and release, flight replay will continue. Click the button again to stop it. This way you can have continuous replay without having to keep the button pressed.

When replaying IGC formatted files the speed and track data are computed and no filtering is done in the computations. Thus if the position and time data are noisy, all speed/track dependent computations will be noisy as well. Magnetic variation is taken from the variation set in the options and the "use GPS variation" setting is disregarded.

It is IGC requirement that GPS altitude values in a file are above WGS84 ellipsoid rather than MSL. If you want the program to display MSL values, you have to enter MSL correction in the NMEA dialog.


In order to have a task appear on your map use the “Setup | Make Task” button on the menu. A list of turnpoints appears in which you can insert (below the selected one) or delete turnpoints. You insert turnpoints by selecting them from a list of turnpoints derived from your file. Once you define your task, it will be displayed on your map drawn with a dashed line (course line). The task is saved to file, so you can reuse it the next time you run the program. It will not however appear, until you define it as above. Clicking on the [Cancel] button reverts to the original task and cancels task display on a map. Numbers to the left of the turnpoint name represent the task leg distance starting at that turnpoint in whatever units you chose in the units tab of options. The last (bottom) number is the total length of the task. Task distances are computed based on WGS84 geoid for earth shape. All other distance calculations are based on spherical earth model. The difference is not worth computing time. Task and leg distances will change if you do an edit assigned area task goal points on a saved task. These distances are computed from goal point to goal point and do not take start nor finish cylinders into account. If some task turnpoints are defined as checkpoints the "All" checkbox becomes active. Toggling its state causes distances to be shown including or excluding the checkpoints.

Checking the "has landing" or "has takeoff" boxes informs the program that the first waypoint in the list is a takeoff point and the last the landing point. These are required for competition task declarations. Takeoff to start and finish to landing site segments are not shown in task displayed on a map. 

You can save task shown on the display to a temporary (while the program is running) task list. Give it a unique name, e.g. "Task A". A new name is suggested each time a task is saved. You can recall previously saved tasks using the arrows in the name edit window. The tasks list thus created can be saved to file and then recalled when you run the program again. task list files are compatible with "Flight Display" and "Flight Analysis" programs and can be used by both interchangeably. They should have extension of TSK. File format details are given below.

Last task list saved or recalled is re-loaded at program startup if possible. This causes the following behaviour: As you open the Make Task dialog, last used task is loaded as default. The "Save As" window shows the "next available name" to save the task to list. If you click on the task selection arrows the default task is lost unless you cancel the dialog. Since the default task more than likely came from the task list you loaded this should not cause a problem. If you know it did not, or want to make certain you do not lose it, click the Save As button to save it. This will save the task in memory, but will not be transferred to file unless you explicitly save tasks to file.

If you edit assigned area task goal points on a task that was selected from the list, these changes are saved so you can go back, select the task and retrieve them. Any edit of turnpoints or takeoff/landing information breaks the connection to selected task and task displayed is treated as being new. You can edit observation zones without breaking the connection. If you do so, it is your responsibility that the edited goal points still fall within new observation zones. If a current task came from the saved list, program shows it as default when you go to make task again.

If a task is read with elevation of a turnpoint missing, program attempts to look it up in its digital elevation data and uses looked up value as turnpoint elevation.

The [Declare Competition Task] button appears only if a valid log file with IGC format logging was established beforehand, you entered this dialog form competition setup, or a FAI certified logger dll is on your system (see this page for module availability). Clicking on it will record the displayed task in a competition declaration format to file. The purpose is to be able to easily declare a task defined during competition setup in case of task change after logging had started. Declaring Competition Task enforces the has takeoff and landing properties.

When a task is written to an IGC file it is "time stamped". Time and date are obtained from GPS if it is connected to the PDA and delivered valid NMEA data within last 30 seconds. Otherwise it is obtained from the system time (UTC) on the PDA. It is important to set the PDA to appropriate time zone.

When you accept the task, it is transferred to destination queue. Takeoff site is not transferred. Neither is the landing site if it has the same name as the finish turnpoint. Names of destinations that come from a task are prefixed with "x," where x can be S-start, F-finish, or the ordinal number of a turnpoint in a task. It is assumed that the destination queue can hold the whole task. After task is transferred, current destination is set to the start turnpoint. Transferring task to destination queue enables auto detection of  observation zones including audible indications of entering and leaving them. In order for this auto-detection to be active "Auto detect" checkbox has to be selected in  Needed Altitude Modes dialogue. If this checkbox is selected prior to transferring task to destination queue, auto-detection is temporarily suspended and a "Start" button appears on the screen. auto-detection is resumed once the button is pressed. This enables one to come in and out of the task start zone without advancing in the destination queue.

You can move turnpoints to change their order in the task definition dialog by dragging. On PDAs you have to start moving the stylus fairly quickly after touching the screen, otherwise system thinks you are selecting an entry for some other purpose and does not send out appropriate messages (the same is true for most other programs). One thing you need to be aware of when dragging turnpoints, is that you drag their observation zones as well, so you have to pay attention to task observation zones dialog that shows up after you click OK.

When accessing this dialog hardware buttons can be used as described above except for the following:


GPS_LOG WinCE draws observation zones after defining a task.You will see this dialog is if you click on [OK],  [Save As] or [Declare Competition Task] in the Task Display. If  have a FAI logger dll on your device you will see the FAI logger checkbox when task is being declared.

When you define the width of line start or finish gate you have to enter half of the full width in the radius window. 

You can define sectors as start and finish gates. These gates will have 90 degree sector angles.

Start gate can be defined as an inverted cylinder ("=>Cylinder" entry). In this case start is defined by entering the cylinder rather than leaving it. Destination display will show "At" no matter how far one is from the start as long as one is outside the cylinder. In this case "At" and "To" have intuitively (but not logically) reversed meaning. Typically such start gates will have large radius and be centered around the first turnpoint. Inverted cylinder gates are treated as turn areas in terms that the task is redrawn to the start point after one enters the cylinder.

Directions for line and sector gates are the same as required flight direction. Directions for turnpoint sectors are those of sector bisector coming from turnpoint into the sector. Directions are recalculated to FAI standard values if you set the All Alike checkbox.  If checkpoints are present in the task, directions for turnpoints are computed skipping checkpoints, these for checkpoints are computed based on neighboring turnpoints (checkpoint or not). Whether computation of start and finish directions is to a checkpoint is controlled by a checkbox in task options.

If  the "All Alike" box is unchecked, you can define different observation zones for each turnpoint. This box is checked as default if the program discovers any problems with turnpoint zone definitions. If the task was recalled from saved data, this checkbox  will probably be cleared. It is a good idea to double check all the values.

If "All Alike" is unchecked and turnpoint has a sector with no cylinder, you can define a sector with a minimum radius by checking the "Min. S. R." checkbox. (this will show an edit box to its right) This is primarily for assigned area tasks, and if you specify minimum radius you will have to make AAT edit of the turnpoint in order to bring it within defined observation zone.

When "All Alike" is unchecked additional checkbox with "TA" label appears. Checking this box declares the turnpoint observation zone to be a turn area, and this is reflected in task declaration made to an IGC file. Declared turn areas can have a cylinder, or sector, but not both. Also, once one leaves an observation zone marked as turn area, program draws task to the point that maximizes distance instead of to the goal point. In addition turn area turnpoints can be re-entered. If you leave a turn area program will direct you to the next turnpoint. However if you return to turn area before reaching next turnpoint that is not a checkpoint, program will roll back the changes and treat the flight as if you just entered the observation zone, except that it remembers previous point that maximized distance.

If selected turnpoint is a checkpoint a "Checkpoint" indicator appears to its left.

Gates with lines are treated as semicircles, to auto detect passing through a gate  you need to enter semicircle and exit through the line. 

If you check the FAI Logger checkbox, the program will attempt to transfer the task to your logger..


When you set up a task the task limitations dialogue will appear after you click on OK in observation zones definition. This will allow you to limit allowed altitude before start and on task as well as to set maximum altitude allowed when crossing start gate and maximum speed that is allowed while doing that. You need to check the appropriate checkboxes to apply these limits. Altitude margins cause in-flight warnings to appear before you hit the limit altitude. All altitude are MSL and pressure altitude is used if available. Otherwise GPS altitude is used. See setting of altimeter (if needed) in alarmed zones options.

In flight program warns you with an alarm sound used for alarmed zones and pops up the note window. If you cancel the notes window by clicking on it, it will not come back unless you go below the warning altitude and come back up. The note will vanish if you go below the margin adjusted limit altitude. The "Before Start" and "On Task" warnings just state that you are flying too high.

If you cross the start too high or too fast the warning note will be shown as "Bad Start" and the second line will show you the violation in form of  "+100ft  +10kts" if you violated just one parameter, only one value will show. You need to cancel this note by clicking on it. As far as the program is concerned you started the task as GPS_LOG does not enforce these limits. If you come back and do a re-start, the note may appear again if the repeat start is bad, but program's task will reset itself just as if everything were OK. The "Before Start" limit is not watched for once you cross the start the first time.

The value you enter as maximum start altitude is saved in task information (even if "START" is left unchecked) and can be used later on for purposes of flight evaluation. However GPS_LOG does not enforce it, thus it ignores a start that happens as you thermal through the top of a cylinder start gate.

FAI triangle checkbox appears only if task satisfies the free distance FAI triangle flight. If checked, task will be created with turn area zones that satisfy FAI rules.


Picture below shows a sequence of screens one sees when editing a turnpoint in an AA task.

Starting screen on the left shows flight in progress to task start (7M Ranch). In order to edit the Ukiah turnpoint one toggles destination to Ukiah and swipes the name left to right as shown by red arrow. Swipe has to start in the first 1/3 of screen width and end in the last 1/3. One can also program a hardware key to enter AAT edit instead of swiping screen.

Program zooms to the selected observation zone and sets the destination to the current task turnpoint. By clicking on the map screen, one moves the turnpoint (observation zone does not move). Turnpoint can be moved only within an observation zone. Map can be moved by dragging, enlarged and shrunk just as in normal operation. Screen area above the navigation information shows modified total task distance (subtracting cylinder radii of start and finish), estimated time remaning on modified task (total estimated time if editing before actual start), current MacCready setting and turnpoint elevation. Mac Cready setting can be modified with the up down buttons. Mac Cready value shown during AAT edit is not remembered and is used only for planning purposes. Turnpoint elevation can be edited with keyboard that will show up if its edit window gets focus. The value in this window is also updated from digital elevation data if a valid AGL file is present. Hitting [Enter] on the keyboard will hide the keyboard. Once you are satisfied with the edit click the [Done] button to return to normal operation.

Clicking the estimated remaining task time toggles it to displaying estimated total task time and vice versa. Estimated total task time is denoted by 'T' following the time, e.g. "2h17T".

Clicking the Mac Cready value will show expected speed (in current units) for the remainder of the task and vice versa. This allows you to set turnpoint goal based on expected speed as opposed to expected Mac Cready value.

You cannot edit start nor finish turnpoints. Program checks that new points falls within selected observation zone. If current task came from a list of tasks maintained by the program, AAT edits are reflected in the list. You can recall the task again with edits preserved.

While AAT edit is active, hardware arrow keys control the MacCready value.


Swiping name of a destination that is not part of a task in a manner similar to that for Assigned Area Task edit, but in the opposite direction, allows one to add that destination to current task after confirmation (message box). Destination is added as last turnpoint (not finish) of a task with a cylinder observation zone. Radius of the observation zone is controlled in task options. If the "Insert as Finish" checkbox is checked in task options, turnpoint is inserted as finish. If finish previously had a line gate, it is replaced by the default cylinder.


If a task contains turn areas (TA box checked in observation zone definition) program computes points that maximize task distance. These points are shown on a map as 1km radius hatched circles as in the picture on the left (here these points are circled with blue lines for clarity). As one leaves a turn area zone, these points are re-computed for following zones based on the maximum distance point achieved in the zone being exited.



If you define a task that satisfies FAI triangle rules, the Task Limits dialog shows a checkbox "FAI triangle". This checkbox is unmarked by default. If it is checked, program creates FAI regulation zones. They are created one at a time as the flight progresses. FAI zone is used together with an "original" observation zone to create Turn Area observation zone. Once you leave that observation zone and your distance to the next turnpoint is less than twice the distance to the point maximizing distance in the existing observation zone, program creates a new zone around next turnpoint based on acumulated information about the flight.

Picture shows zone about first turnpoint for a case of a task that allows distance of 750km.  FAI zones are drawn to a shape calculated accurately on a plane. Approximating earth sphericity and projection leads to drawing errors on the order of 1km in the shapes I've seen. Rule checking in flight is accurate.

If you create a real triangle task (4 points), program adds another turnpoint with small cylinder observation zone at the finish location. This is necessary for turn area operation of the combined zone.

As the above implies, finish gate can underly previous turnpoint FAI zone.

Using computation of needed altitude around the last turnpoint should be disabled when FAI zones are present, It does not make a lot of sense to use it in any case.

One cannot add waypoints to task with FAI zones in flight.


GPS_LOG program also provides help to a pilot that wants to fly FAI triangles without declaring them. In order to enable this support one has to check the "Show free task FAI zones" checkbox in Task options.  

Setting and clearing turnpoints is done via Setup|"Free FAI task" menu entries, or by mapping these functions to hardware keys. Unless you set it on the ground, the first turnpoint is set on takeoff (not much of a difference).

You can clear a turnpoint if you want to move it somewhere else, or you set it just to find out where the turnpoint zones are.  You can clear only the last turnpoint you set or eliminate task completely (Reset). The latter may only be useful if you land and re-start. First task leg must be 15km or longer. Second leg must be longer than 0.55* first leg. Unless the minima are met you cannot set a turnpoint.

Once you clear a turnpoint, you can re-store it. If you set a turnpoint after clearing one, re-store toggles between the cleared and set turnpoint.

Two FAI zones are displayed before second turnpoint is set (but after minimum distance is met).  After the second turnpoint is set, program displays one or two zones depending on your position. Setting third turnpoint results in a single zone towards the first turnpoint. In addition, program displays 1km radius, gray shaded circles around set turnpoints.

Free FAI task is not shown if a task is set. Neither can you set a free FAI task turnpoint in that case. You can however clear previously set turnpoint, or reset the task.



GPS_LOG offers an option for members of a team to share their position information that is easy to transmit and is not readily understood by others that do not know the basis for position encoding. There are three user interface elements of this feature: display of your position in encoded form,  set of options for enabling team information and selecting the encoding, and a dialog where you can enter someone else's location and turn it into a destination. Clicking the "??" button on the display of your position opens up a dialog shown in the picture on the left.

You can enter position information either using keyboard or buttons on this dialog. the "<" button is a backspace key and erases the last entered character.

Clicking the "?" button displays distance and magnetic bearing to the encoded location. If elevation of that location can be found in the AGL data, it is also displayed.

Clicking the "GO TO" button (or Enter on keyboard) turns the location into destination waypoint and puts it in the destination queue.


You can edit some parameters without going through menus. To access that capability you have to swipe the upper half of the navigation display showing time/position and track/wind... The swipe has to be at least half of the width of this display and can be in either direction. After swiping you will see an edit window as shown here. You can also bring this window up by pressing the hardware Action button.

You can change the (WGT) weight factor (current wing loading/ wing loading of the polar file), (BGS) bugs induced degradation of polar performance in percent, (L/D) default glide ratio to be used if polar is not used, (MC) manual MacCready value, and (Wnd) wind. Use the up down spin button to change the values, click the value name to toggle between parameters and click OK to exit the edit. Editing parameters this way does not change the default value that is set in options. However, if you open options, currently selected value will be entered in appropriate fields and may be set as default for the future.

In case of editing wind, the wind value is shown in current units and the angle in true degrees. You change the angle by clicking areas above and below it as marked on the picture. Wind set this way is remembered only till the next time it is set automatically by instrument, or manually while thermalling.

When you edit MacCready value, you can also set which value is currently active: manual (M) or automatic (A) by clicking the letter shown. This is not available if automatic MacCready is not allowed in thermalling options.

When the parameter editing window is visible it takes over the operation of buttons and arrow keys. Up/Down arrows have function of the spin button, Left/Right arrows and keys 2 and 3 change the secondary parameter like wind direction or MacCready value type. Pressing key 4 followed by pressing key 1 results in changing the parameter to be set, while pressing key 1 followed by pressing key 4 is equivalent to pressing OK. Arrow keys will output a continuous stream of signals, for various system related reasons button keys should not be held down for too long, are debounced for 1/4 second, and need to be "pecked" for multiple changes. Pressing "Action Button" while the parameter edit window is visible is equivalent to clicking "OK".


When approaching a turnpoint program switches scale of the display so that you can see the details of your flight. Map scale is chosen so that the turnpoint "fills" the screen. If a turnpoint is larger than what would fit on display given current scale of a map, program does not zoom out. when you leave the turnpoint, or switch destination, map scale reverts to the original one.


Zoomed mode is really designed for thermalling. It  allows you to temporarily zoom the map display to some predetermined resolution (options parameter) and then come back to the previous map display. The “magnifying glass” button toggles between the zoomed and unzoomed states. When you toggle the map state you automatically re-center the map. The zoomed map span is remembered while the program is running, but is not saved to file.

Map rotation is suppressed while in zoomed mode. North is on top of the map. Data display automatically switches to the Vario display. Dots marking the track are slightly bigger for better visibility.                   

While in the zoomed mode it is assumed that you are circling, and after the first circle the program starts looking for maximum and minimum speed in each circle. It interprets the difference as due to the wind. As you keep circling it averages the value of wind velocity derived from the minimum and maximum speed in each circle and displays it instead of the TOG: on the screen (see below). Double clicking on displayed values result in saving the value for future computations involving wind. To reset the wind averaging double click on ”DRFT” in zoomed mode. The wind speed and direction thus derived, is sensitive to the averaging filters of your GPS unit. It is also sensitive to your ability of keeping the indicated speed constant while thermalling. 

 In zoomed mode, map centering may seem a bit confusing at times.  The program attempts to center on the center of last circle rather  than on the current position. However, if the center was not yet established or the map needs to be re-centered more than once in a circle, the program temporarily gives up and centers on the current position.  


Needed altitudes to reach a destination are computed in two different modes. While one is cruising, needed altitude is computed based on current speed and wind. While you are thermalling it is computed assuming that you fly at a speed that maximizes flown distance.  Vertical air motion is disregarded. You can take Mac Cready setting into account by checking the "Use Mac Cready" checkbox in "Needed Altitudes" dialog. This checkbox has no effect on altitudes shown in destination selection lists, nor when you click on a symbol. These altitudes are computed based on best achievable glide (0 Mac Cready setting). Checking the "Constant speed" checkbox in needed altitude modes dialog causes the program to use speed calculated in the last thermal or when MacCready setting changed instead of current one while cruising. Needed altitude can be displayed as difference between current GPS reported altitude (not pressure altitude) and altitude needed to reach destination. This is indicated by + or - signs in front of digits. Setting is remembered from one program session to another. You can toggle this setting by (double) clicking on the displayed needed altitude.

Alternatively, if a final glide Mac Cready display is selected,

needed altitude is computed based on speed to fly determined in last thermal which is related to the Mc value. The algorithm for determining the speed and Mac Cready values is as follows: As long as you are below the altitude necessary to reach destination at best speed MC value is zero, and speed is the best speed. Once you are above that altitude, maximum speed is computed for you to reach the destination, and equivalent MC value is determined from that speed. Two computations are done, one with wind correction and one without. When you toggle wind correction, the appropriate values come up. If you are interested in reaching your destination in minimum time, you should climb as long as your climb rate is higher than the MC value shown. This display can be turned on automatically while thermalling by a setting in the second tab of miscellaneous options.

If you are using digital elavation (AGL) information to compute needed altitudes, they are also used to compute values in the Mac Cready display. For a single segment final glide values are computed as if there were no obstacles and the resulting flight path is compared to the terrain. If there is an obstacle, values are recomputed to the obstacle. Then during final glide program checks whether you are closer to the destination than the obstacle and recomputes the Mac Cready display values if you are. Thus you may start your final glide at a small MC value setting, and see it switch to a higher one during final glide. Calculation for a final glide via last turnpoint is more complicated, but basically the same applies.

You toggle between the normal and MacCready display by (double) clicking in the center of the destination display. When Mac Cready display is selected, you can transfer the "recommended" Mac Cready setting to the one used in other computations by (double) clicking it and confirming the transfer (this will not work if a supported vario instrument is present). Mac Cready display is active only when you are using polars information for computations. Mc and speed for this display are updated when you are thermalling (after one circle), if you manually enter wind,  destination changes, and when the status of "Include last Turnpoint" (see below) changes. When last turnpoint is included in computation, the suggested speed to fly on the first leg shown in Mac Cready display does not strictly guarantee minimum time to finish, but should be a close approximation (exact value can be computed, but it involves time that computer can better spend doing something else).

Other needed altitude features are controlled through the needed altitude modes dialog accessible through "Setup" menu.

"Use MacCready" checkbox controls whether or not Mac Cready setting is used to determine needed altitude while thermalling.

"Use AGL" controls whether digital elevation data is used in order to determine needed altitude. For more information see below.  Program requires half of the set pattern altitude clear an obstacle.

Checking the "Show difference" box results in difference between current GPS reported altitude (not pressure altitude) and altitude needed to reach destination to be displayed in "GOTO" button and waypoint selection dialog when looking for landouts. Needed altitude needs to be displayed as difference in the navigation window as well for this setting to be implemented.

"Show to Finish" box controls whether needed altitude is computed to a general destination, or to a finish point on task. You have to have a task set up before you can check this box. Once this feature is active you cannot click through destinations. You can cancel this mode, by selecting another destination either from a map, or by asking for landouts or destinations, or by un-checking the box on this dialog. This feature is also activated if you send task to destination queue. This setting can be toggled using a hardware key by configuring one of them to mean "Toggle Show Finish" on the key options tab.

"Show to Next turnpoint" is similar to "Show to Finish", but Next turnpoint is used instead of finish. See more details on navigating to next turnpoint below. You have to have passed task start for this functionality to be enabled.

"Include last turnpoint" allows you to compute altitude needed to go to last turnpoint and then to the finish. in this mode a "+" sign is preppended to the displayed destination name. This option can be toggled by clicking on the name of the finish site shown as destination on the display. If you select "Show to Next turnpoint", label on this box changes to "Include current Turnpoint". See more details on this below.

If you check "Auto-detect", "Include last Turnpoint" setting will be cancelled once you come within distance entered in the "Radius" box to the last turnpoint. If you choose Auto-detect, but not "Show to finish", the program will automatically switch the destination to the next one in the queue once you LEAVE the circle of the selected radius around current destination. The destination display will display "At" instead of "To" when you are within the circle.  If a destination is a task point with an observation zone, the observation zone is used to determine whether to display "At" or "To". Checking auto-detect also enables sound indicators for tasks. Auto-detect is temporarily disabled once a task is transferred to destination queue. It is re-enabled when the "Start" button that appears at that time is clicked.

When "Auto zoom" and "Auto-detect" checkboxes are selected, program will zoom map display automatically as you approach a waypoint even if it is not a task turnpoint. This occurs at a distance equal to sum of the auto-detect radius and about 1/2 mile.

When using glider polar to predict needed altitude GPS_LOG WinCE subtracts altitude that can be gained by slowing down to best L/D speed of the glider. How much of this correction is made depends on the value in the Total Energy factor box. 0-none, 1-full correction.

Constant speed box controls whether while cruising program uses constant speed computed while thermalling for needed altitude computations. This speed is also recalculated if MacCready, wind or destination setting change. When polar is active the state of this box is indicated by appearance of the toggle polar mode button on the left side of the map window. Speed used for computations can be seen as "v:..." string in the information display. Its presence is controlled by display options.

Once you select a polar curve on the “Polars” tab of options you can use it  for needed  altitude computation. You can also choose to use default glide ratio in calculations. You can also change this default in the same tab of the options. Data are fit to the equation:

      v_sink = a + b* speed + c * speed^2

and the glide ratio is derived from this. There is no guarantee that your glider's polar obeys above equations, though it ought to be  reasonable approximations. For safety's sake I suggest you build some reasonable air sink speed into the polar data. Otherwise you will probably be getting overly optimistic estimates for altitude.

Double clicking on "To:" or "To>" toggles wind corrections for the calculation of estimate of the altitude needed to reach destination. You know when the correction is active because the destination data start with "To>" instead of "To:" and because the heading will be displayed (if wind is valid) as (e.g.) "34L" (meaning turn 34 degrees left) rather than "168m" meaning magnetic bearing of 168 degrees.  

THIS DOES NOT TAKE INTO ACCOUNT VERTICAL AIR MOTION. If you are not asking for the wind correction then calculation is done based on the glide ratio calculated from glider polar at the GPS indicated speed. The reported altitude is a sum of destination elevation,  pattern altitude and the distance/glide ratio. If you ask for wind correction, glide ratio is computed based on the estimated airspeed (unless a suitable instrument is present) which is derived from GPS provided ground velocity vector and wind velocity vector. Furthermore, actual path required to travel is computed based on the estimated air speed,  wind and bearing to the waypoint. "NO GO" is displayed if  required altitude is greater than 100000 feet (100kF). Altitude estimate is displayed only for waypoints with known elevation. For speeds less than 5 knots needed altitude defaults to "NO GO". This is done to avoid possible division by zero in the  program. The 5 knots limit is arbitrary and was chosen because it is well below any realistic stall speed. You can select a different speed by appropriately editing your polar data file (see format below), but you cannot set it below 5 kts. This limitation is not imposed if you use a default,  speed independent glide ratio.


Once one passes start, one can ask program to navigate to "Next turnpoint". In general one will navigate to it via current (this) turnpoint, but this is optional and can be toggled by clicking on the name of "Next turnpoint" shown in the navigation part of the screen. When current turnpoint is included a "+" is shown next to "next turnpoint' name and program calculates needed altitude to the next turnpoint based on flight path around "this turnpoint". Also, if current turnpoint is included, flight direction shown by the program is to "this turnpoint". When one enters observation zone of "this turnpoint" while it is included in computations, a sound is played, navigation to next turnpoint is automatically turned off, and program automatically navigates to "next turnpoint" (but see below for Turn Area turnpoints). This change in navigation is normally done when one exits observation zone rather than enters it.  "This turnpoint" is advanced automatically whenever one enters observation zone of turnpoint one is navigating to.

When you ask for navigation to "Next turnpoint" program determines which turnpoint it is, based on the last turnpoint which you rounded properly. If you miss a turnpoint you will not get what you may expect until you reach a turnpoint to which the program is navigating to. If you miss the intermediate turnpoint while navigating to "Next turnpoint" in general you would have cancelled navigation to next turnpoint, or at least cancelled navigation through intermediate turnpoint long before you reach the "Next turnpoint".

While navigating to next turnpoint via intermediate turnpoint, the GoTo line is drawn to "this turnpoint", also auto zoom to turnpoint observation zone turns off immediately after one enters observation zone, so it may appear as if it did not happen.

Since one navigates to "next turnpoint" immediately after entering "this turnpoint" observation zone, this functionality would be of questionable utility if zone around "this turnpoint" is a turn area. They are usually very large.  If the intermediate turnpoint observation zone is a turn area, navigation to "next point" is cancelled only after one leaves that area. "This turnpoint" is advanced at the same time.


If you are using digital elevation data file for deriving AGL information you can also use it to take terrain shape into account when computing needed altitudes. By clicking in the center of the lowest line of the destination display as you toggle between standard and Mac Cready displays you can toggle to the "Ground Clearance" display. You have to have "Use AGL" checkbox selected in the Altitude modes dialog. The display looks as follows:

In order to understand better the information contained in the last line take a look at the following diagram:

In the display above the "G:" line reads: collision with ground  expected in 5.8 miles. Height of the highest obstacle with respect to flight path is 300 feet and its distance is 17.7 miles. Accuracy of the distance is determined by data spatial grid, and the height is an estimate as it assumes projected flight path. When you are thermalling the flight path is calculated based on currently set Mac Cready value or Mac Cready value of 0 depending on the setting of the "Use MacCready" checkbox in "Altitude modes" dialog. In straight flight it is calculated based on current speed (or last speed determined while thermalling if you have "Constant Speed" checked). If you are expected to clear the obstacles, collision distance value is not displayed and clearance height value becomes positive.

When "Use AGL" checkbox is selected, terrain data are also used to determine needed altitudes when selecting a landout or clicking on a map symbol. You can see the difference this makes in a mountainous terrain by looking at the following composite picture:

You can see the glider position at the beginning of a flight in a mountainous region. On the right you see two windows from landout selection one with terrain information turned off one with it on. You notice that the airport selection is radically different. Notice also that in the bottoms elector Stead airport is missing even though Eagles Roost and Spanish Springs are listed. There is a sizeable hill in the path between the glider and Stead that shadows the airport. In spite of that Stead is reachable easier than either one of the other two by slight deviation from the straight path. Just because you have and use terrain data does not mean that the results are perfect and that you are absolved from thinking. Program requires half of the set pattern altitude to clear an obstacle.

If your glider position, or destination position fall outside of elevation map coverage, program reports needed altitude as if you were not taking terrain into consideration. NO WARNING is given. It is pilot's responsibility to use appropriate files for any given flight. You can check coverage for your position by looking at the AGL height value. It will show "G: ??" if you are outside data coverage (or your altitude is unknown).

Terrain data are also used for computing suggested Mac Cready value. For more details see description above.


If you set the program to use digital elevation map data in Needed Altitudes Modes dialog, you can also get visual information on terrain. You call up the terrain profile screen by swiping the destination display more or less vertically (preferably down) as shown in the picture to the left, or by clicking around the G letter if it is showing. You can also program a hardware key to show terrain profile.
Following pictures show what you can expect to see:

First one shows elevation profile display in straight flight in this case program displays ground section along extension of ground track. Distance shown is 50 km or distance to destination plus 2km, whichever is longer. A thin vertical line marks distance to destination (but not necessarily location as your track may not be pointing at it. bottom of the graph is at minimum elevation of ground profile not at zero elevation. markers along the top are every 10 km or 5 statute or nautical miles depending on your choice of distance units. The vertical marker to the left starting from the top of the picture represents 1000 ft, or 300m depending on your choice of  altitude units. “> 89R” is the course correction to destination just as in standard destination display. The slanting lines represent your expected glide path. The thin line represents path at best L/D speed for zero MacCready setting, the thick one corresponds to your current speed.

Second one shows what you see while thermalling. Name of the destination is on the left, destination itself is on the very right. The thick sloping line represents the glide path calculated based on zero, or current MacCready setting depending on what you chose in Needed Altitude Modes dialog for needed altitude calculations. The thin line is calculated always at zero MacCready setting.

Clicking  on the right one third of the terrain profile picture toggles its vertical size if possible. This way you can see terrain profile simoultaneously with flight status data.

Things get a bit more complicated if you choose "Show to Finish" and "Include last Turnpoint":

In that case the vertical line in the straight flight  forward looking picture represents distance to last turnpoint, not to finish.

When you are thermalling both segments are shown on display, destination shown on the left is the last turnpoint, and the ground profile shown, is along expected flight path (current position, turnpoint, finish) Flight path shows two separate segments calculated separately (as for reporting needed altitude). Note that the glide slopes are different due to wind correction.

Regardless of whether you are thermalling or not, program puts a marker on a map if a ground impact is expected on the line joining your position and destination. This is shown in the picture on the right. Note the red-white-black shape between glider position cursor and the end of the Goto line. Healdsburg airport is not on this map. Ground impact marker was removed from the left picture for clarity.



If digital elevation data (AGL data) are available and used by setting a checkbox in Needed Altitudes Modes dialog program will display an outline of terrain that can be covered in Final glide. Outline is computed at a number of points and represents a line where you can expect to be at pattern altitude after starting at current location flying at best speed for the wind (if wind correction is used) in still air at a given MacCready setting. Display of the outline is enabled by setting the "Show accessible region" checkbox in reachable outline options. Number of points and MacCready setting used for computations are set in reachable outline options. Number of points can be set in the range of 48 to 200. Use the minimum number of points that gives you acceptable results, otherwise computations are not going to be updated very often unless you have high performance machine.

Reachable terrain outline is computed roughly once every half minute in normal operation and once every few seconds during flight replay. Color of the outline varies depending on underlying background. It is dark green on white field.



GPS_LOG supports overlays on maps. There are two kinds of overlays. "Permanent" consisting of polygons defined with symbol 27 or -27 that are permanently coded in a map, and a "variable" overlay that is defined by selecting an overlay file from file menu. Overlay objects are drawn on top of topography and alarm objects layers and before any other shapes. Variable overlay file cannot contain any alarm objects and all shapes contained in it are put in overlay file and drawn in order of appearance. Overlay can be shown or hidden (not displayed) in response to action menu command and toggling can be assigned to a hardware button. Action menu overlay command is disabled if there are no overlay shapes. Typical use for an overlay would be weather information, or some detailed map information that might take long time to draw or decrease readability of map, but useful for occasional reference.


This is an experimental capability. It may or may not work depending on your hardware and environment as well as internet server availability. It is not available for devices with 2.01 operating system.

At this point the internet server supporting this functionality is still under development. If you are interested in trying it, please contact me at for more details.

When flying with GPS_LOG WinCE on a device with internet connection (e.g. through GPRS Web Access Phone) one can establish connection and report position to an internet server. Ones position and task information may then be made available in real time to other internet users. To enable this functionality you need to install an additional module GPS_LOGinternetDLL.dll. When installed, a "Web Server" entry appears on the setup menu. Clicking it shows a dialog used to establish connection to the server. Top combo box allows you to select your dial-up connection. When the "Connect using" checkbox is unchecked, currently available Internet connection is used if present. Timeout entry how long GPS_LOG WinCE waits for response from a server, and the Port parameter controls the internet port on which communication is done. In response to data from the program, server may issue messages or warnings in response. Messages appear as message boxes that vanish after a time defined in the "Message timeout" entry. Setting this entry to zero disables messages, but not warnings. Warnings have to be cleared by the user.

Prior to using this program feature you should go through competition headers setup and fill out pilot name, glider registration number, class .... The glider registration number is particularly important as it is the primary unique identifier. This information is sent to the server when communication is established.

GPS_LOG WinCE collects GPS data every 12 seconds to be sent to a server and sends them every two minutes (this may change at some point). It also sends the server task information when a task is defined or added to. Right now it does not report canceling of a task. Thus the server knows the last task defined.

If the internet connection is lost, the program attempts to reconnect (re-dial) automatically. You may get warning messages if data are getting lost due to lack of internet connection for several minutes. Transmissions end when program is terminated. You can also terminate transmissions by clicking Web Server menu entry again and confirming the disconnect.


Using the Export Map .. entry on File menu you can export map image to a Windows bitmap and generate a calibration file that later can be used in the Flight Display program. This option is available only for the PC version of the program. Its availability is further limited by your computer memory size and may be grayed out if map objects are not stored in memory.

Size the map window and move and scale the map until you get the map extent you want exported showing in the window. You may need to adjust the "Map Scale" factor in the Maps options temporarily to get exactly what you want. Click the menu entry, select bitmap file and fill out the properties dialog. Checking the "256 colors" limits the bitmap size by restricting the color space. Bitmaps can take up a lot of memory and disk space. Currently no checks are made on memory nor disk constraints. Image enlargement factor controls how much bigger the bitmap drawing area is compared to the window on the display. File size grows as square of that factor. 

Neither flight trace, nor a task are exported to the bitmap file.

A calibration file (*.flt) is generated with the same file name as the bitmap - only the extensions differ. This file contains information needed for Flight Display program.


GPS_LOG WinCE accepts pressure altitude information from Zander SR940 and other instruments that use the same format. Pressure altitude reported by these instruments is used for computations and is logged to file.

LX Navigation  (Filser) INSTRUMENTS support

If LX-160 vario is available in the system, GPS_LOG WinCE uses data it provides for pressure altitude, air speed, rate of climb and Mac Cready setting, bugs setting and optionally ballast information for computing polars. LX 160 bugs setting overrides the one set in options. Additional parameter display is also available which shows polar efficiency (100%-bugs) and ballast setting . Toggle to it as to other displays. It is assumed that only one instrument is in the system.

Other LX Navigation instruments that provide similar data will behave in the same way. Wind information provided by these instruments can be used only if direction and magnitude are output.


If Borgelt B50 super vario is available in the system, GPS_LOG WinCE uses data it provides for air speed (true and indicated), rate of climb and Mac Cready setting, bugs setting and optionally ballast information for computing polars. B50 bugs setting overrides the one set in options. Additional parameter display is also available which shows polar efficiency (100%-bugs), ballast setting and outside air temperature. Toggle to it as to other displays. It is assumed that only one instrument is in the system.


GPS_LOG WinCE uses data it provides for pressure altitude, rate of climb and wind. When using this instrument it is important that the altimeter setting is done properly in the Alarm Zones options. This instrument reports altitude corrected for altimeter setting, but reports that setting only when changed.  Until program detects instrument altimeter setting it is using its own setting to recover standard pressure altitude.

The SN10 outputs wind data together with a confidence factor. GPS_LOG WinCE will accept wind data if the confidence factor is greater than 70%.


When Cambridge 302 digital variometer is detected in the system variometer display shows "relative vario" value in place of instantaneous climb rate. This is demarcated by value being surrounded by "] ... [". Averager time constant is determined by 302 not computed. 302 bug setting is ignored and ballast setting is displayed as in the case of Borgelt B50. Pressure altitude output by 302 is logged and used for IAS computation. This unit also outputs wind data. They can be used by setting wind determination method to "Instrument". It is assumed that only one instrument is in the system. 


You can connect handheld running GPS_LOG WinCE to GPS_NAV data port. When starting, GPS_LOG WinCE will initialize the data port to transmit NMEA data. It will also perform this initialization on serial port reset. In order for this to work you have to have GPSlgFAI.dll in the \Windows folder that is designed for GPS_NAV. This works only with program version or higher.

GPSlgFAI.dll module will pause program when necessary so that you can switch cables between GPS_NAV data port and the GPS source you are using when doing task declaration to GPS_NAV.

VW921 INSTRUMENT support

VW921 version 3.3  is supported by this program. When Westerboer VW921 instrument is detected in the system variometer display shows "netto vario" value in place of instantaneous climb rate. This is demarcated by value being surrounded by "] ... [". Average climb rate displayed is determined by the program, not by the instrument. VW921 does NOT output UTC time nor GPS determined altitude. In order to compensate for that, time is generated by your computer, and pressure altitude output by instrument is used in place of GPS value. This unit also outputs wind data and MacCready value. Winds can be used by setting wind determination method to "Instrument". It is assumed that only one instrument is in the system. VW921 MacCready value is used unless program is set to automatic MacCready setting. When the VW921 value is used, it is followed by "B" and cannot be changed by the program.


 Pressure altitude reported by this instrument is used for computations and is logged to file. A shareware module is available that allows task transfer from GPS_LOG WinCE to Volkslogger for competitions, e.t.c. that require a FAI certified logger.

EW logger INSTRUMENT support

A shareware module is available that allows task transfer from GPS_LOG WinCE to EW logger for competitions, e.t.c. that require a FAI certified logger.


Pressure altitude reported (enable the GPWIN sentence) by this instrument is used for computations and is logged to file. This logger does not output GPS altitude. GPS_LOG WinCE uses the pressure altitude in place of GPS altitude. This in particular affects the IGC log file and display of needed altitude in difference mode.


GPS_LOG WinCE understands the PTAS1 sentences sent by Tasman Flight Pack, model Fp10. It uses pressure altitude, variometer, average variometer,  and TAS readings as reported by the instrument.

FLARM support

FLARM support requires a dynamic link library FLARM_DLL.dll Installer for this dll is available from site.

Only FLARM version 2.0 and above as documented on 16 Feb. 2005 is supported. Using the program with previous FLARM versions may lead to unpredictable results.

There are two versions of FLARM module, one that supports safety features described here, and another, which also supports task declaration on IGC capable FLARM units. Both have the same file name.

Alarm information provided by PFLAU sentences are translated into sounds each sound is composed of up to four sub-sounds e.g. "Aircraft - two o'clock - above - orange". Which sub-sounds are voiced is controlled by FLARM options by the corresponding type-bearing-altitude-urgency checkbox. Since the sub-sounds are played separately in a parallel thread program may add gaps in between to allow other threads to run. Program attempts to correct FLARM bearing information for wind if wind corrections for flight navigation is requested. It issues "level" altitude information if the alarm object is within +-70m or +-10 degrees of user's altitude.

Sub-sounds are saved in the following files that can be modified but have to be extremely short. These files should be in "My Documents\GPS_LOG WinCE" folder or above in it's hierarchy.

fl00#!b.wav   - 12 o’clock
fl01#!b.wav   -  1 o’clock
fl02#!b.wav   -  2 o’clock
fl03#!b.wav   -  3 o’clock
fl04#!b.wav   -  4 o’clock
fl05#!b.wav   -  5 o’clock
fl06#!b.wav   -  6 o’clock
fl07#!b.wav   -  7 o’clock
fl08#!b.wav   -  8 o’clock
fl09#!b.wav   -  9 o’clock
fl10#!b.wav   - 10 o’clock
fl11#!b.wav   - 11 o’clock

fl00#!h.wav   - below
fl01#!h.wav   - level
fl02#!h.wav   - above

fl00#!l.wav   - green
fl01#!l.wav   - orange
fl02#!l.wav   - red

fl00#!t.wav   - aircraft
fl01#!t.wav   - obstacle
fl02#!t.wav   - new traffic  - this is information message, level sound is not played

FLARM devices provide also information on other FLARM devices in the vicinity of the receiver. This information comes as PFLAA sentences and requires data rate to be set to at least 19200 baud on the FLARM unit. GPS_LOG uses it to display a Traffic Collision Avoidance System like display. This display overlays about 1/4 of the map window and shows position of other devices in relation to one's glider. A glider icon shows up in the center of the display. TCAS display shows roughly 3000 or 8000 meter radius around receiving unit. Color (red,green, yellow) of the symbols corresponds to the alarm level, and shape corresponds to relative altitude. Circle - level (see above ), Up arrow - target is above, Down arrow - target is below. TCAS display shows up only if there is information to be shown. Range radius is toggled by clicking the top right corner of TCAS display. A gray rectangle is displayed in the top right corner when radius is 8000m. Range toggling is available only in module versions and above.

Newer versions of FLARM module allow one to visualize climb rate of targets in TCAS window. Target has to transmit that information and be a glider, hang glider or paraglider. Climb rate is represented y symbols to the right of target shape."-" for -1<= Vz[knot] <=+1, "^" for +1<Vz<=+3, "^^" for +3<Vz<=+7 and  "^^^" for +7<Vz. Inverted "^" are used for negative Vz. Climb rate is enabled in FLARM options. Enabling and disabling of this feature is logged to IGC logs and that information is protected by file security codes.

You can enable "follow the leader" feature in  FLARM options. If that feature is enabled and the green circle in the picture above corresponds to the glider you are following, TCAS display shows relative direction in the bottom left corner and distance in kilometers in bottom right. 'R' indicates turn to the right 'L' to the left. See  FLARM options for information on how the glider to be followed is selected.
There are some possible artifacts in TCAS display as there are limitations to information provided by FLARM:

GPS_LOG WinCE FLARM module provides support for FLARM net  In order to use it, download Winpilot version of FLARM net data base file  from this page or use direct link. Rename the file to FLARMdata.fln and place in the same folder as the sound wave files above. Now if you click in the lower right corner of the TCAS display shows while it displays targets that have been entered in the data base, a window will show up with a list of available targets. The window lists pilot/club name, glider registration and radio frequency. Listing is sorted with the newest arrivals at the top of the list. If competition ID for a glider is available it is added as a prefix to pilot name followed by a period. Clicking the "Follow" button on that window will result in glider selected in the list to be entered as the leader to be followed (see above), but will not affect the GPS_LOG WinCE "follow the leader" data base file ("FLARM_dta.fdt", see  FLARM options).


RESETTING all options

Starting with version a companion program GPS_LOGreset is distributed in installation packages. A shortcut to it is created alongside with the shortcut to main program. You can use this program to reset all options to default state and/or clear the "competition data base".

You can also save all current settings including the IGC headers data base to a file and then reload them at some other time. Settings are saved to a binary file with a GPR extension. When loading from file a complete erasure is done before loading, so if your file is corrupted, you will end up with all default settings.

MENU descriptions

Select file for saving data.
Select file from which waypoints are extracted.
Select file with map information.
Select file with overlay information. If selection is cancelled user is asked whether to remove current overlay file.

Select file with elevation data.
Save binary image of the map to speed up map loading (see below).
Select file with logged track to replay.
Save or load a set of tasks that can be displayed on a map or declared for competition. If a current task came from a program task list, new tasks cannot be loaded until current task is cancelled. Last set of tasks is re-loaded at program startup.

Reset the RS232 port in case of trouble (probably to no avail). 
After serial port is reset you should hear an "OK" beep.

Exit the program.


The "Save Binary Map..." menu entry gives two options : "Complete..." and  "Crop...". The Crop option allows one to define boundaries of the new map as defined in map bounds dialog that shows up after clicking it.


The PC version (GPS_LOG Win32) has two additional File menu entries:

Resetting the RS232 port may cause event triggering that you may not have intended. If that matters, you should set the event options to "None" beforehand.


Select a waypoint for new destination.
Select a new destination from a list of closest landing sites.
Create a waypoint from current position.
Edit dropped symbols on current map. Program cycles through all of them.

Center map on current position.
Expand map.
Contract map.
Flip map 180 degrees.

Toggle between normal and thermalling modes
Hide, show or show destination part only of navigation text
Toggle polar on and off for glide ratio calculation (used when checked). Toggling this entry is equivalent to clicking the "Toggle polar mode" button on left hand of a map.
Hide or show overlay.

Task submenu functions work only if task is defined and current destination satisfies appropriate conditions. AAT Edit allows to edit a turnpoint, Add to task adds current destination to task.


Hard reset of stopwatch to 0.
Setup NMEA communication options.
Setup various program settings.

Enter/view wind information.
Control how needed altitude is calculated and displayed

Add symbol to current map.
Add waypoint to current waypoint file.
Setup a task to be displayed on the map.
Prepare for competition task.



NMEA interface:

NMEA Code – a combination of NMEA sentences used for position and track information. This does not affect altitude readings, nor anything else. Use VW921 setting for VW921 instrument that does not output data in NMEA format. Check Length and RX_FLAG settings are ignored in that case.

Serial port (COM port) can be either selected from the list, or typed in. List shows serial ports made visible by the system. Some PDAs suffer from COM ports not being properly identified in registry. Thus sometimes it is necessary to type in the port you know to use. If a Windows Mobile 5 or higher device is used and it has a built in GPS you may see an entry #gpsAPI at the beginning of the list. Selecting this entry will cause program to use system calls to retrieve GPS information. This is preferred mode for using internal GPS for WM5 and higher devices. When using #gpsAPI, baud rate, Use RX_FLAG and continuous settings are ignored. RMC NMEA code has to be selected to use #gpsAPI. In addition to #gpsAPI  you may see an entry like @gps-0 at the beginning of serial port list. Such an entry points to information stored in the registry of your computer for hardware COM port device at which one should find GPS. Selecting such an entry results in program attempting to use com port and baud rate stored in computer registry. Upon re-entry to NMEA setup dialog this information will be shown in appropriate list boxes.

Check Length – check for lengths of NMEA sentences if checksum is not supplied in order to validate them. This option is not available for versions and greater. It is always set. If your GPS does not supply checksum you may find that data reception is not very reliable.

Use RX_FLAG – a more efficient use of program resources, but some older WindowsCE units did not support it, neither do modern iPaqs.

MSL offset - some GPS units send GGA sentence without reporting geoid separation (height of MSL above the WGS84 ellipsoid). Enter appropriate value here. If your GPS reports geoid separation this value will be overridden.

SiRF GGA - some GPS units send GGA sentence with height above ellipsoid instead of MSL (SiRF chipset version 2.3 in particular). Select this checkbox to correct for this behaviour.

Auto reset - if this box is checked, clicking on the NoGPS indicator results in resetting serial port if it had not received a data character within past 20 seconds. This may be of some use with Bluetooth based GPS links, but is of questionable value otherwise. Checking this box also causes the NoGPS indicator to reappear after about 3 minutes if no valid GPS data arrived. On PDA's with WindowsCE version 3.0 and higher checking this checkbox causes serial port to be reset when power is turned on while program is running. If you do not want this to happen, delete GPS_LOGwakeup.exe program from \Windows folder after each installation. After serial port is reset you should hear an "OK" beep.

When "Auto reset" is selected, program attempts to find appropriate baud rate if no NMEA data came in within last 4 and a half seconds. It cycles through seven baud rates (4800, 9600, 14400, 19200, 28800, 38400, 57600). When NMEA sentences are detected, search is stopped. Baud rate search is re-started if no NMEA sentences appear within 4,5 seconds.  This means that search should be successful within about 1/2 minute, but you also may end up with 1/2 minute gaps if something goes temporarily wrong. Do not use auto reset if your NMEA source sends messages less often than every 4 seconds. Because searching for baud rate is almost certain to generate a lot of communication framing and buffer overflow errors, logging of these errors is disabled if search is enabled. Otherwise, logged framing errors are a useful indicator of something going wrong in wiring and buffer overflow errors may indicate troubles in code keeping up with data.

 "Auto reset" setting takes place immediately (you do not need to click OK). If you are in the NMEA setup and auto baud search is enabled you will see data rate switching every 4,5 seconds or so.

The “Continuous” checkbox is primarily intended for Bluetooth devices with poorly implemented device drivers (like in case of several iPaqs). Check it if your serial port seems to lock-up. Checking it also overrides the setting of the “Use RX_FLAG” checkbox

The "Ignore errors" checkbox is another option to deal with incompetence with serial port driver programmers. Some serial port drivers (notably iPaq rz1710 with SDIO SD-510 GPS) report errors continuously, whether error occurred or not. Checking this box results in program ignoring all serial port driver reported errors and thus receiving data from such units. When this option is selected you lose logging of errors to IGC file which provide early warnings of cable and other connection problems that might occur in normal operation due to wear.

Some PDAs (like T-mobile MDA Compact 3) have such horrible COM implementation that both "Continuous" and "Ignore errors" boxes need to be checked. Try this if all else fails.

Clicking OK on this dialog resets your RS232 interface. This may cause event triggering that you may not have intended. If that matters, you should set the event options to "None" before setting NMEA options.

You can set baud rate either by selecting one of the predefined values, or by typing in your own value in the baud rate window.

Towards the bottom of the dialog there is a window that shows data coming in on the serial port. This feature is disabled for VW921 code, as Westerboer sends out binary data. Serial port settings are set only after you press OK, so the data window uses previous serial port settings, not necessarily the ones you see on the dialog. In general if serial port is receiving data, you will see something flashing in the data window too fast to read. However as NMEA data come in bursts, you should be seeing (part) of the last NMEA sentence before a break.


There are two tabs for miscellaneous options.

Use UTM – when checked, position data will be logged and displayed in UTM (Universal Transverse Mercator) format.

Decimal minutes – when checked, position data will be shown with minutes in decimal format, otherwise seconds will be displayed.

Use double click – when checked you need to double click on the display to change an item to be shown, otherwise single debounced click is used.

Use GPS variation – When checked, the variation value will be derived from GPS data, otherwise enter your own value.

Dest. # - maximum number of destinations that can be in the destination display queue. This number is overridden if a task that is being transferred to queue has more turnpoints that would fit otherwise. Queue is extended to fit the task for the duration of program session.

FIFO - when checked, destinations are added to the queue based on First In First Out. When unchecked, new destination is added "in front" of currently displayed destination replacing whichever destination was there before.

Time zone offset – set to display local time rather than UTC.

Time in seconds - display elapsed time in hours-minutes format rather than decimal hours

Earth radius – value to be used for distance computations, which assume spherical earth shape.

Replay Interval [sec] - minimum time in seconds between logged data to be shown during file replay. Increase this value for long files and slow computers.

Pattern Altitude - enter the value of  altitude above ground you want to arrive at a landing location. This value is used when needed altitude is computed.

GLYPHCACHE - use this option with care. This setting should appear only on handhelds with operating system 3.0 or higher. It permanently changes a setting in registry that has to do with how operating system draws to display. When set to a large value it may (reported on iPaq, but I did not see it on Aero) speed-up map drawing. This value is not changed back when program exits, so it will affect other programs as well. Value that appears in the window when this dialog is reached, reflects current setting (8 is default for Pocket PC). It may be that you need to "reboot" your handheld before the value takes effect.

If Circling - you have an option to automatically switch displayed information when the program detects that you are circling. None - does nothing, Vario - switches to climb rate display while circling, Wind - switches to wind information while circling (this is useful if you use the 'Track Auto" method of calculating winds aloft). 
Show MacCready checkbox controls whether Mac Cready needed altitude display is automatically switched on while thermalling.

Load map at startup - when checked, last used map is loaded when program starts. This sometimes may take a while.

Remember navigation state -  when checked program starts in the same display state as left last time you run the program. Otherwise full navigation display is shown.

Speed commander - when checked, program provides audible indication on whether one should fly faster or slower. No sounds are played while circling and if the difference between speed to fly and the actual indicated speed is smaller than the value in the Speed tolerance box. Speed tolerance is given in currently used speed units.

Gear warning at: - fill in the AGL altitude threshold for gear warning. Setting this negative will disable the warning and set the value to -999 ft.

Default startup MacCready - value for manual Mac Cready setting to be used at program startup.


Log on ….- GPS data does not come all in one sentence. This option controls when data are saved to file, e.g. if in your data burst VTG sentence comes after GGA sentence and you are logging speed and track, you should log on speed, when using the GGA-VTG combination. The same applies to sentences coming from Compass and true air speed instruments. THIS SET OF OPTIONS IS AVAILABLE ONLY IN PROGRAM VERSION OLDER THAN Later versions log on position.

Warn at xxx KB - if you have less than xxxKB disk space left when opening a log file you will be given a warning. Program also reports file system errors while logging, but by then it may be too late.

Format – IGC = International Gliding Commission format read by many other programs, Standard = coma delimited format useful for spreadsheets…., 

Log All Types – If not checked only position and altitude data are logged. Not applicable to the IGC format.

Raw – while this box is checked the program sends all received data to a \My Documents\GPS_LOG WinCE\rawGPS_LOGdata##!!.txt file. This file is never erased by the program and new data are appended to it. This is mostly for debugging purposes and it is in addition to the normal logging. If the file cannot be saved to the above folder, the program tries to save it further up the directory tree.

Save Dropped Waypoints - When this box is checked dropping a waypoint results in it being stored to current map and waypoint file. Unchecking it causes a dropped waypoint to be saved to map only.

 Log Interval – controls how often data are saved to file. The larger the number, the less often. Setting this value to 0 will disable logging. You can use this to temporarily stop logging without closing logging file. When using VW921 instrument this value cannot be set to 1. However if log interval is not set to zero, all positions are logged while proximity to a turnpoint is detected, or position is within observation zone of a task turnpoint ("At" indication in destination display). If log interval is set to zero, program will not ask for log file name at startup and a log file will not be created. If you change log interval from zero to another value while logging is not in progress you will be asked for a log file name. If you start a log file while log interval is 0, log interval will be overridden, and logging starts immediately with log interval=1 if file is created during competition setup, or log interval =2 otherwise.

Screen Interval – minimum time in seconds between screen updates. Use this to prevent excessive screen flickering on slower machines. Even on fast ones reading navigational data that changes once a second may be difficult.

Log flights to logbook - if this box is checked program detects when aircraft is in flight by checking if the indicated airspeed (computed or from instrument) is larger than some fraction of stall speed defined in second line of polars file. When landing is detected, or program is exited, flight is recorded to XGL_LgBk.txt file in "My Documents" folder. Under some rare circumstances (e.g. in high winds) program may detect a false landing in which case more than one flight will be recorded. Here is a typical logbook entry (pilot and glider information is taken from competition headers setup):

    Pilot: John Doe
    Glider ID: NyyyXX
    takeoff: 2009-02-16 21:25:20 UTC 38,46.190N 122,34.264W 945f
    landing: 2009-02-16 22:05:51 UTC 38,45.621N 122,34.078W 942f

Logbook to Storage Card - selecting this box results in saving flight logbook to flash card in "\Storage Card\My Documents\" folder. If flash card is not available data are saved to PDA RAM.


Dot Space – minimum distance in pixels for placing track dots.

Dot size – controls the size (visibility) of track dots.

Margin – fraction of the window size which is “out of bounds”. When the cursor gets into the margin, map is re-centered. Margin has to be set to less than 25% to enable re-centering at about 1/3 of screen height when auto-rotating.

Blink Time  - cursor blink period.

Scale Factor – the factor by which the map is expanded or contracted on each command.

Def. Radius – (in miles) radius of a circle that will fit on a default generated map. This map is generated when 1) GPS position data come before a map is selected, 2) you cancel map selection. The map is centered on current position.

Track Cache Length – maximum number of positions saved to cache for redrawing of track when map moves or resizes. You can decrease and increase the cache size. However if you try to increase it beyond the size created at program startup, you have to exit the program and re-start it before the change will take effect. If you come back to map options before restarting the program cache length will revert to previous setting.

Track Cache Frequency – the number controls how often a track position is saved to cache. This value is disregarded while in thermalling mode (all data are saved).

Rotate to TOG - controls whether the map rotates to keep current heading pointed up (TOG means Track Over Ground).

Min. Angle - minimum change in track over ground before the map can rotate. 

Show GOTO line - Show or hide course line to destination.

Distance for map simplification - (PC version only) maximum distance for an eliminated point to be from a resulting line.

Create elevation map - If this checkbox is selected program will create a background topographic map displaying ground elevation from digital elevation data. This option will be cancelled if device is not capable to create such a map.

Use multiple map files - Checking this option allows the program to load multiple files simultaneously. When asked for a map file program presents the following dialog:

Use "Add" and "Delete" buttons to control which files appear in the list of additional files. Use "Up" and "Down" buttons to control the order in which the files are loaded into the program. File may appear on the list, but not be loaded. When a file is selected in the list, the "Use selected file" checkbox controls whether it will be loaded or not. Additional files may be located any place on the disk, but only ends of file paths are shown on the list.

When using multiple maps all maps, including the main map have to be present. Program will not create an empty default main map.

Restricted Airspace Alarms:

Map format allows you to specify alarm zones around restricted airspace or other features you should not fly through. This set of options controls when the alarm is triggered. You can effectively enlarge the airspace so that alarm is sounded before you actually enter it.

Barometer - enter required altimeter setting in this window. Entry is in units of 0.01 inchHg or 0.1hPa depending on current units setting. This will correct pressure altitude received from an instrument. Correction is done AFTER pressure altitude is logged to file. If the instrument sent pressure altitude is already corrected for barometric pressure leave the setting at 2992 (or 10132).  When the program is started it attempts to determine altimeter setting from GPS and pressure sensor data. It will do that only if speed read from GPS is less than 4 knots for a couple of minutes. Changing the altimeter setting (or just clicking on its value in this dialog) suppresses automatic setting.

Transition altitude - altitude above which barometer should be set  to the standard setting of  2992 (or 10132) rather than "airport" setting. Program automatically switches between the standard and "airport" setting to determine altitudes for comparison to alarm zone boundaries and task limitations. Note that the way pressure altitude is computed in the vicinity of transition altitude is not necessarily intuitive as one can see in the drawing. This can have effect on when alarms are being sounded if alarm zone bottom (or top) is close to transition altitude.

Altitude Guards:
    Above - altitude buffer above restricted zone feature.
    Below - altitude buffer below restricted zone feature.

    Changes in altitude guard features take place immediately.

Horizontal Guard  - horizontal buffer around the airspace. Horizontal Guard margin is included in shapes of map elements saved to binary files. When a binary map is read, saved options take precedence over ones that appear on the options dialog until the horizontal guard value in the dialog is changed. If you are not certain what is in the file, you should force recalculation of boundaries by changing value in the options window, and then re-save the file in binary format. 

Use pressure altitude - if available, barometric pressure derived altitude will be used instead of GPS measured one to test entry into an airspace.

Show enlarged - when checked, enlarged shapes of airspace are shown on a map. When showing enlarged airspace, some artifacts may be visible around concave corners when there are several corners in close proximity. Airspace enlargement assumes that shape border does not cross itself ( no "figure eight" allowed ). If both, the "Show enlarged "and "Show Outline" boxes are checked, program shows enlarged shape as an outline around original shape as in the picture to the left.

Alarm OFF permanent - if this box is checked holding the [Alarm] annunciator button down for about two seconds turns off alarm for the zone that triggered it till map is re-read.

Display permanently OFF zones - if this checkbox is cleared, images of SUA that have alarms turned off permanently are not displayed. This option will work properly on binary maps only if they were created from text maps by GPS_LOG WinXX version or higher.

Accurate check - if your computer is fast enough, check this box to get notes only from the zones you actually click on the map, rather than from all that include the clicked point in their bounding rectangle. Note: You have to drop down the software keyboard in order to see this checkbox.


# Init. Turns – number of circles you need to complete before wind calculations start. This gives you a chance to stabilize in a thermal.

Cache Length – number of cached positions redrawn when map is refreshed.

Radius – (in meters) radius of a circle that will fit in an initially displayed thermal mode map.

Search time - amount of time that you can drop below minimum rate of direction change without being taken out of the zoomed mode automatically.

Show Climb – climb rate greater than average is indicated as larger dot in the thermalling mode.

Display Map – show current map symbols while in thermalling mode.

Draw Lines - draws lines instead of dots while thermalling.

Auto Zoom - when checked program will switch to thermal zoom display after the initial circles and switch to normal display after circling stops.

Minimum Rate - minimum track change rate for the flight to be considered  circling. Above that rate wind can be determined from track data as long as circling is not interrupted before a predetermined number of circles is made.

Show thermal climb average - when checked climb rate averaged over themal duration is shown in vario display.

Automatic MacCready - MacCready value is computed based on a number of previous thermals and set for computing speed to fly. This checkbox controls whether automatic setting is allowed. You toggle between manual and automatic setting by clicking on the display of Mac Cready value in the vario display. When automatic setting is in effect Mac Cready value is displayed with an "a" following it.

Thermals for MacCready - Number of thermals taken into account for computing MacCready value. Thermals are weighted with the last one being most important, previous one less and so on in an exponential manner. The value entered is gives the weight exponential decay length. Only thermals with three or more circles are taken into account


Use:  -  controls, whether polar curve data or the default glide ratio are used for needed altitude calculations. You can also toggle this entry by clicking on the "Toggle polar mode" to the left of a map.

Weight Factor – weight of your glider relative to the value used for the polar curve.

Instrument - if Borgelt B50 or LX-160 instrument is available, weight factor can be set on it in flight and used by this program. the same applies for other supported instruments, though some of them may require you to setup the Ballast/Weight % field.

Ballast/Weight % - Some instruments (like Cambridge 302 digital vario) report setting of percentage of ballast rather than a weight factor. In that case, in order to use instrument information you need to fill this field by the ratio (in percent) of maximum water ballast weight to weight of sailplane flying without the ballast, and use polar for the no ballast weight.

Bugs % - degradation of polar (and default) performance expressed as percentage increase of sink speed at any air speed. This setting is NOT remembered across program sessions. It is reset to zero at the beginning of a run. When Borgelt B50 vario is present this setting is overridden by the one from instrument.

Vario Averaging Time – averaging time to determine the climb rates. The average value is used for speed to fly calculations.


Reset clock on start controls whether the stopwatch is hard reset  to 0 as one crosses the start line.

POST radius is the default observation zone cylinder radius applied when one inserts a turnpoint in a task.

Start/Finish in checkpoint direction – If  this is checked, start and finish directions are computed to next/previous turnpoint even if it is a checkpoint.

Insert as Finish - when checked, destinations are inserted to task at finish position instead of last turnpoint.

Update finish line gate - when checked the finish direction for a line gate will be updated on insertion of a turnpoint. There may be safety related reasons why this direction should not change for a given competition.

Allow GOTO line - when checked, GOTO line is displayed while there is an active task if allowed in map options.

Minimum turnpoint zone margin - minimum distance from turnpoint observation zone boundary at which program will zoom map onto the turnpoint if appropriate.

GOTO line to optimal AAT point - if this is checked GOTO line is drawn to a point in assigned area task zone which gives longest task distance, otherwise it points to the task goal point.

Show free task FAI zones - checking this box enables FAI triangle flight support without task declaration


This set of options enables and controls calculation and display of team location report. If "Enable team information" checkbox is checked the position display can be clicked through to show current position in a form encoded based on a team waypoint defined in this dialog. You can use your waypoint file to import a waypoint using the "From File" button. Precision of encoding is controlled by the selection of grid using radio buttons. The smaller the grid the more characters you can expect to have to read or enter for encoded information. 

All members of the team have to use the same team waypoint and grid.

User also has a choice of using GPS_LOG, SeeYou or WinPilot codes to communicate with other team members. If User chooses his own code, this is equivalent of using Passworded SeeYou communication. Currently used user code is displayed in the list of selectable codes, so one can come back to it if one changes one's mind while entering new code. Grid selection is relevant only for GPS_LOG code.


Use to select a set of your preferred units (distance, speed, altitude).
these units are used for display purposes only. Units change takes effect the next time any particular displayed value is updated (not necessarily when display is refreshed). You should not change units if you changed, or are planning to change any other settings at the same time.

Note that displayed units change only after new GPS data come in and display is updated. This is particularly evident at program startup, when default strings are displayed until first update.

Values controlling the Universal Transverse Mercator map datum.






This set of options controls which parameters can be displayed to the right of ground track information. As you click on that part of the display you cycle through the set of checked parameters. If none are selected, altitude is displayed.

L/D is derived from average climb rate and ground speed. If you climb "L/D ++" is displayed.

IAS ("I: ..." string) displays GPS derived ground speed corrected for altitude. In absence of wind it should be the same as the value shown by airspeed indicator. The difference will give indication of head wind "component".

Constant speed ( "v:..." string ) displays constant speed used in needed altitude computations with polars when requested

Outside air temperature (OAT) box matters only if instrument connected to the PDA sends the temperature information.

If "Auto cycle" box is checked, program cycles through all displayable parameters.

Resolution set of options is available only on PocketPC 2003 Second Edition and above. It controls how a VGA screen is used. When set to QVGA, maps are drawn at the 320*240 resolution. When set to "partial" maps lines and symbols are about 2/3 of the QVGA size. VGA setting displays maps with small symbols and thinnest lines. You need to restart the program for resolution settings to take effect.

 The "Allow to hide toolbar" checkbox is available only on PocketPC Windows CE 3.0 or higher. When selected, it allows you to toggle bottom toolbar on and off. Toolbar icon used to change waypoint file is replaced by circle with an X. Clicking it, hides toolbar and shows a circle and triangle button in left bottom corner of map window. Clicking that button restores the toolbar. You should not switch to other applications while toolbar is hidden.



GPS_LOG WinCE can estimate distance you are flying. This set of options specifies how many segments (legs) are considered to make up the flight and whether the distance estimate is computed to current position, or current destination. Each segment is given a weight, so (e.g.) if you have two segments in your flight each of them 50km long, but assign weight of 50% to the second segment, program will display 75km instead of 100km. Program looks for the first zero weight to determine number of segments to compute distance over. for the case shown in the picture, distance is computed for 4 segments. Computation maximizes distance under constraint of number of segments and segment weights. No other constraints are imposed.

Computation is quite lengthy and is running in the background. In order to accomplish it in reasonable time, flight is simplified. Time it takes to compute distance is proportional to (number of flight points)^(number of segments -1). In order to minimize computation time, flights with more than 4 segments are more simplified. You can switch number of segments in flights, but then different parts of your flight will be simplified in different ways. To give you an idea of times involved: on Compaq Aero 1550 a 500km, 5.5 hour flight simplified to about 80 points. Toward the end of the flight, distance computation with four segments took about 4 minutes.

Points used to determine the distance segments are recorded at the end of a log file. Format is as "LXGLMDPx 3846208N12234295W", where x is consecutive number starting at zero, and location is recorded as in B position records. Starting a new log file resets distance flown to zero.


Speeds - Minimum and maximum speeds for which compass NMEA sentences are considered valid. These speeds are entered in current units as shown in the frame text.

Tolerances - speed in (knots, or miles, or km)/second, turn in degrees/second. Maximum rates of change for wind computation. Flight below these values is considered stable. If in addition speed is also in min-max range, flight is considered straight and level. The turn tolerance is also used to determine whether map rotation can occur.

Compass Heading - Magnetic heading reported by compass when the dialog became active.

Deviation - enter (+/-) correction for compass heading.

True Heading HCHDG - check this box if your compass outputs true heading in the HCHDG NMEA sentence. The standard specifies magnetic, but some instruments (like Garmin eTrek Summit) report true.


Method - Select method by which winds are computed. See Winds for more description.

Compute on: - for smallest errors you should set this to the last NMEA sentence type that comes in a set. Some of the options may be disabled depending on the Method setting.

Minimum Turn - Compass method requires multiple data sets at different angles. Set this to a minimum required change in track angle. For compass method this should be in the 30 to 80 degrees range.

Minimum Speed - Enter minimum speed required for computations to take place for "Compass"  and "All three" methods. Meaning of minimum speed depends on the computation method. For "Compass" this is speed over ground,  and "All three" it is the true air speed, for other methods it is not applicable.

Winds from TAS and ground velocity:

When wind is determined from TAS and ground velocity, multiple readings (points) of TAS and ground velocity are taken and wind is computed by best fit to readings. When a new reading is taken all previous points that are within "Minimum turn" in ground direction AND "Minimum speed change" in TAS are eliminated. In addition, previous points that now are either too old ( "Maximum time span" ), or to far in altitude  ( "Maximum altitude span" ) are eliminated.

In order for fit computation to be done, a minimum number of readings (points) must be saved and for re-computation there is a minimum number of new points that have to been added. Readings are taken only if flight is stable (see Compass options).

Uncertainty: Three parameters determining whether wind fit result is accepted. Goodness of fit is determined by wind confidence measured in the same units as wind. For weak winds, defined as wind*"Wind Fraction"<"uncertainty at low winds" parameter, result is accepted if wind confidence is less than the "uncertainty at low winds" parameter. For larger winds the confidence has to be smaller than wind*"Wind Fraction" and smaller than the "uncertainty at high winds" parameter for the result to be accepted.


Use this tab of options to adjust fonts appearing in navigation display, in maps and waypoint selection dialogue. The program was designed around Arial font. However, in some cases you may want to minimise application footprint and save storage space used by it. Also some (especially older) units do not support True Type fonts. Only one font face can be selected, but sizes can be adjusted independently for the three cases. As you change size, or face samples change their appearance. This selection is made available immediately and remembered from program session to another. Typically the map legend font is not bold, but you have an option to set it bold. 

The "Notes in bold font" checkbox controls font in the window that shows notes associated with zone alarms, map symbols and destinations.

The "Three line notes" checkbox toggles font size in the note boxes to display information in up to two or three lines of text without scrolling.

When correcting for winds this program tells you whether to turn left or right on in destination display. You can replace the English R and L by arrow symbols (if they are in your font) or by language specific letters (checkbox not shown).

Note: This program was designed around using Arial font. It will work fine with other True Type fonts. Some (especially older) WindowsCE units do not support True Type. What you will get will depend on manufacturer's implementation. I will not try to fix it.

"Program Keys" mapping:

You can map four "program keys" available on PocketPC and PalmPC (OS>=2.11) onto appropriate actions.

Alternative Method checkbox - programatically there are two ways to capture program buttons. It appears that some PDAs work with one, but not another. Most work equally well with either. If you have troubles with program keys try switching the method.

Selecting the "Arrows -Destinations" checkbox maps hardware arrow keys to perform following actions:
Left Arrow - switch between track, wind and vario display in second line of navigation data
Right Arrow - switch between position, time and task display in first line of navigation data
Up arrow - move forward in the destination queue
Down arrow - move back in the destination queue
Hardware arrow keys perform these functions only if the software input panel is hidden and there is no regular keyboard. Otherwise, they just move a map around.
Scroll the bar on the right hand side to show hidden choices.

Toggle line 1 - is equivalent to clicking the left hand side of the top line in the navigation display (position, time, track) to change its content.
Toggle line 2 - is equivalent to clicking the left hand side of the second line in the navigation display (track, vario, wind) to change its content.
Toggle value - is equivalent of clicking on the right hand side of the second line to change the parameter (altitude, speed to fly.....) or toggle from automatic to manual Mac Cready setting.  If the track line is displayed on the first line this action will apply to the first line rather than second.

Add to task - allows a keypress to add current destination to task.

Screen power - this choice allows one to use a hardware key to toggle power to the screen system. You can use it to save battery power if all you are doing is logging data. This capability is highly dependent on manufacturer's implementation of screen power capabilities. In some cases clicking other keys may revive the display, toggling power on and off should turn display on .... There may be different unforeseen consequences of using this feature. Test it out before using it in flight. In the worst case scenario it may be necessary to hard reset your PDA resulting in loss of all data. In general however toggling PDA power switch should reset things.

AAT edit - allows to enter AAT edit of a task turnpoint by pressing hardware key.

Events (PEV,STArt,FINish,ONTask) - if one of these is selected, pressing hardware key results in an appropriate event marker being written to IGC file. PEV stands for "Pilot Event"


see above.

Reachable outline:

This set of options is related to display of reachable terrain outline. Checking the "Use current MacCready setting" box results in the value used for outline computations to be the same as the one used for speed to fly and needed altitude computations. Otherwise value defined in default setting is used.



The checkboxes Urgency, Type, Bearing, and Altitude control which sounds are played upon receiving FLARM alarm information. The order in which sounds are played is determined by the selection in the "Order" list box.

When the "Follow" box is checked, program displays direction and distance to a glider having selected FLARM ID. The ID is selected either by typing it into the drop down box window as shown on the bottom of the picture, or is selected from the combo box list. List is filled from a file called "FLARM_dta.fdt" which has to be either in "My Documents" or "My Documents\GPS_LOG WINCE" folder. As all GPS_LOG data files it is expected to be UTF8 type. Each text line in the file corresponds to an entry in the list box. Line starts with FLARM ID followed immediately by a coma and a "friendly name" that appears in the list box, eg:
    DD9C3C,Student pilot
    DDBECC,Group Leader
only first 16 characters of a friendly name matter and they have to be unique.

"Show TCAS" checkbox controls whether Traffic Collision Avoidance System display is shown on top of a map if FLARM unit provides appropriate data. TCAS window has two display ranges: short (3km) and long (8km). You toggle between ranges by clicking topright corner of TCAS window. You can also assign a key to do toggling. Range at program startup is defined by the "Startup TCAS range" option selection. A circle corresponding to the short range is displayed while in long range setting if "Show short range circle" box ix set.

"LargeTCAS size" - checking this box results in TCAS display being twice its normal size, pretty much obliterating the map. This setting is overridden in thermalling mode.

"Show climb rate" - when this checkbox is marked GPS_LOG WinCE shows climb rate of gliders, hang gliders and paragliders in the TCAS display. Fact that this display is enabled is logged to IGC log file.

 It is not sufficient to select baud rate in the FLARM options. One has to select and press the "Baud rate" button. This should set GPS LOG and FLARM unit to the same data rate. For FLARM unit to be set, it has to be able to communicate with GPS_LOG on the old baud rate. Once GPS_LOG is set to a baud rate in the NMEA setup, it becomes the "suggested" rate in FLARM options.


These settings are available only for devices running Windows CE operating system 3.0 and above and requires additional installation of a DLL module and setup utility.

Options dialog contains a checkbox determining whether backlight is being controlled. If this box is checked program switches backlight to the configuration selected under "Use this configuration" list. Tis is done upon exiting the settings and when program starts. Upon exiting the program backlight is set to the configuration selected in "RESET to this configuration" list.

Information on backlight configurations is stored in a file "\My Documents\GPS_LOG WinCE\^GPS_LG^bkl.gbl". This file is generated by an auxiliary utility BacklightControl.exe

BacklightControl.exe is installed by default together with BacklightDLL.dll module. Installer puts it in the same directory as GPS_LOG WinCE program. When it is first run it generates "\My Documents\GPS_LOG WinCE\^GPS_LG^bkl.gbl" file that will contain backlight configurations. Before using the dll in GPS_LOG you need to generate these configurations one by one. Start the Backlight Control program. Switch to PDA backlight settings and set up the configuration you want make certain to set timeouts and brightness for battery and AC operation and whether you want screen clicks to turn backlight on or not. All that information is saved in a configuration. Return back to BacklightControl program by minimizing settings, type appropriate name in the dropdown list window and click "Add". Repeat the process to add as many configurations as you want. If you make a mistake, select the configuration in question and click "Remove". Configuration will remain on file, but will be inaccessible.

After you record configurations to file, you may want to click "Setup". This will open up options dialog as above. If you enable backlight control, BacklightControl program will behave as defined in the options. This options dialog does not control GPS_LOG program. You need to set GPS_LOG backlight options when running it.

After you are finished click "Done". You can return to BacklightControl at any time (except when running GPS_LOG WinCE) to add or remove configurations.


In order to generate user defined symbols you should put a symbol list file named ^GPS_LG#^.SLF in the "\My Documents\GPS_LOG WinCE" folder or above in the hierarchy tree. First line of that file has to contain number of symbols you are trying to define. Maximum currently is 20. This is followed by lines containing a number in the range of 1-16, comma, and name of a bitmap file containing symbol you are trying to generate. There has to be no spaces around the coma, but you can replace coma by space. Bitmap files can be generated with Microsoft Paint program (or equivalent) and have to be placed in the same folder as the ^GPS_LG#^.SLF file. Lines are terminated with CR+LF. 

Symbol bitmaps have to be 32 by 32 bits. With symbol image centered. Note that if you use symbol legends you should keep actual nontransparent part of symbols to about 16 by 16. 16 color bitmaps work best. Symbols are not scaled as a map contracts or expands.

A typical symbol list file might look as follows:


Note that there is no number before "City.bmp" this causes the number to default to 1. Also, second bitmap is not existent,  It is ignored.

The number in front of a file name represents transparent color in the bitmap. The following list maps transparent colors:

 1- white
 2 - black
 3 - dark gray
 4 - gray
 5 -dark blue
 6 - blue
 7 - dark cyan
 8 - cyan
 9 - dark green
10 - green
11 - dark yellow
12 - yellow
13 - dark red
14 - red
15 - dark magenta
16 - magenta
any other number - transparent color is defined by the top leftmost pixel of the bitmap.


The flashing arrow cursor showing current position can be replaced by a shape of user's choice. In order to do that one has to generate eight bitmaps. One for each cursor orientations (north, northeast, east, southeast....) Bitmaps have to be 32 by 32 pixels. They can be larger, but only the top left 32*32 part will be used. Top left corner pixel of the bitmap defines transparent color. In addition to the bitmaps program needs a list file called GPS_LG_CUR.TXT This file and the bitmap files have to be together in the "\My Documents\GPS_LOG WinCE" folder or above in the hierarchy tree. Format of the GPS_LG_CUR.TXT file is as follows:

GPS_LOG BMP position cursor library list

First line has to start with "GPS_LOG" (case sensitive).
Second line has a number (bitmap size) it has to be 32.
Third through tenth line give names of bitmap files in the north, northeast, east... order.
Empty line at the end.

In general one should supply 8 cursor files. If fewer images are supplied the missing ones are replaced by the default arrow cursors. If more than eight are supplied the cursor is changed every 360/N degrees, where N is the number of supplied images.

UTM vs. Lon/Lat formats in MAP and WAYPOINT files:

All examples below are given in the Longitude/Latitude format. It is acceptable to input data in the UTM format. Shown below is the field comparison:


    Lat.deg , Lat.min , Lat.sec , Lon.deg , Lon.min ,Lon.sec


    400 , 0  ,0 , Northing , zone , Easting

The zone is positive in the northern hemisphere and negative in the southern.  The "400,0,0" are internal file constants and as such must not be changed.  

WAYPOINT file format

In addition to data files formatted as below, GPS_LOG WinCE can read  TAB formatted file available on internet ( Worldwide Soaring Turnpoint Exchange ). These files typically have a "tab" extension. GPS_LOG WinCE also can read IGC coma delimited waypoint format files.

When reading a TAB file this program uses the following fields:  Name, North/South, Latitude [degrees], Latitude [minutes], Latitude [seconds], East/West, Longitude [degrees], Longitude [minutes], Longitude [seconds], Elevation[Feet].  Others, following these fields, are ignored. Note that the first file field, ‘Number’, does not have to be present for this program to function, but any other irregularity will cause problems. Note also that in the tab format there are other fields interspersed with the above.

Tabbed format is used for reading only. Any file edits are made in the GPS_LOG coma delimited format described below. Both formats can be mixed within the same file. Tabbed format does not support notes, but you can still mark landouts with "^" as below, and the comment character ";" is honored at the beginning of a line.

Starting with program version the following fields are required of IGC coma delimited format files in order:  "waypoint", "optional", ... "optional",  "latitude", "longitude", "waypoint title", "waypoint description", "skipped", "altitude", "type". Optional fields do not have to be there, but if they are, they cannot be interpreted as latitude. The skipped field can have anything in it. Waypoint title becomes waypoint name and waypoint description becomes a note attached to it.

When reading  IGC coma delimited waypoint format files the following rules apply: 1) the "optional" hemisphere marker letters in longitude and latitude fields have to be present and follow digits without spaces. 2) altitudes in meters have to have the "M" demarcator following digits immediately,  otherwise feet are assumed. 3) The "Exact" field is treated as a note comment, 4) Waypoint entries containing "L" in the "Type" field are considered landouts. "A","G""... are ignored. Any file edits are made in the GPS_LOG coma delimited format described below. Both formats can be mixed within the same file.

Altitudes in waypoint files are assumed to be in feet. Adding M after altitude value (e.g.15.4M ) will make program interpret it as meters. If you place a line that starts with "Alt[M]" (no quotes) as the first line of  a waypoint file, altitude values will be assumed to be in meters unless suffix F is added to altitude value (e.g. 350F ).

GPS_LOG coma delimited formatted file is a simple coma delimited UTF8 file assumed to have "dta" extension. Most ASCII files  used for the program prior to version are compatible with UTF8 encoding and can be used without any changes. However if the file contains characters that fall outside standard ASCII (character number less than 128) then these characters may get lost or cause more serious problems. If you are dealing with this kind of file you should translate it to UTF8 encoding, or place a comment line ";ASC" (no quotes) at the very beginning of the file. Even before the "Alt[m]" line. Using UTF8 encoding allows one to use full range of Unicode characters in the program, so names of waypoints can be expressed in any language be it English, Russian, Greek, Chinese, Japanese... The read algorithm is not very forgiving, so do not make mistakes.

If a line starts with ";" character, that line is ignored as a comment.

Aerial Cableways,35,51,30,117,7,0
\^Air Sailing,39,52,30,119,42,0,4300
123.3Mhz\Nice airport in the desert
Alpine County,38,44,30,119,46,0,5867
; this is a comment
\^Angwin (Parret),38,35,0,122,26,5,1848

The name of the waypoint is followed by it's latitude, longitude and altitude. Only the first 19 characters of a name are displayed by the program. Altitude is in feet(or meters), and the longitude and latitude in degrees, minutes, seconds. You can use floating point format (the absolute values will be added deg+(min+sec/60.)/60. ). To indicate south latitude put "-" in front of latitude degrees. To indicate east longitudes put "-" in front of longitude degrees (no spaces in either case). Longitudes must be in the -180 to +180 range, and latitudes in -90 to +90 range. For UTM coordinates see above.  

If you do not know the altitude then enter -1 (or enter nothing after longitude seconds, not even spaces) in the above examples both Austin and Aerial Cableways waypoints have no known altitude.  If you want to enter elevation in meters add "M" after the number as in Melbourne example above.  

The caret "^" as the first character identifies a landing site. It is not displayed in the destination waypoint selection listings, but is used for the closest landouts search.

The “\” as the first character indicates that the following line is a note attached to the waypoint. All “\” characters in the note are translated into CR\LF pairs to format a new line.

The “\” as the first character also indicates that there may be image and/or sound information files attached to a given waypoint. If there is a note the file names are in lines following the note, otherwise thy start immediately after the waypoint line. See examples of Air Sailing and Angwin above. File name information starts with the comment character ';' followed by pound sign '#'. That is followed by 'i' for images and by 's' for sounds. Then file name is given without any spaces before it. If the file name starts with '\' it can refer to any storage location. Otherwise it is relative to the directory containing the GPSLG!LT.WAV zone alert sound.

Displaying waypoints on a map

You can display your waypoints on a moving map. in order to do that you have to have elevation field in format above filled in. If you do not have validelevation enter "-1". Following the elevation there are three coma delimited fields: symbol number, and two fields controlling appearance of the symbol on a map depending on its scale. For instance:

\^Air Sailing,39,52,30,119,42,0,4300, 5,0,800
123.3Mhz\Nice airport in the desert
;note the space before symbol number

There has to be at least one space following the coma preceding symbol number. Fields controlling appearance are optional. If they are missing, symbols defined this way are shown always. Notes are attached to symbols if present, and if a waypoint is marked as a landing place with "^", symbol is given altitude and can be a map selectable waypoint. You can also provide the necessary information while adding a waypoint within the program.

If you want a waypoint to be selectable on a map even if it is not landable, replace coma after symbol number with "^", e.g.:

Mt Rose Peak ,39,20,38,119,55,9.7,10813, 11^10,900


Waypoint defined symbols are not saved to binary map files, and vanish if you change the waypoint file.

MAP file format:

In addition to format described below GPS_LOG WinCE has its own binary format for maps. these binary maps load much faster, but you cannot add symbols to them. You create a binary map by saving your current map with the "Save Binary Map" entry on file menu.

A companion program for converting ESRI shapefile formatted maps to GPS_LOG WinCE maps is provided in the GPS_LOG Win32 (Windows PC) distribution package.

This is also an UTF8 comma delimited file, but with many more possibilities. Most ASCII files  used for the program prior to version are compatible with UTF8 encoding and can be used without any changes. However if the file contains characters that fall outside standard ASCII (character number less than 128) then these characters may get lost or cause more serious problems. If you are dealing with this kind of file you should translate it to UTF8 encoding, or place a comment line ";ASC" (no quotes) at the very beginning of the file.

Map coordinates are encoded following rules used in Waypoint files (see above).

Comment lines are allowed and denoted by ";" as the first character in the line e.g.:

;This is a comment
; and another

Comments can appear any place in the file.

The first meaningful line in the file has to look as follows:


Minimum latitude, minimum longitude, maximum latitude, maximum longitude, and first circle radius in miles (more about this later). Note:  maximum and minimum means just that; -20 (maximum) is more than -25 (minimum). If you are in eastern or southern hemispheres, take this into account. In the line above "M" indicates that all circles and arc radii in this map are specified in miles. Change it to "K" or "N" if you want to use kilometers or nautical miles. The number following it specifies absolute scale of the map before any expansion or contraction. This is used on to determine whether controlled display symbols are hidden or not (see below). It does not matter what units are used for this number, but if you are displaying maps in the zoomed thermalling mode then you should enter here the larger of the north-south or east-west distance ( determined by the first 12 parameters on this line ) expressed in status miles.

Warning: Versions of GPS_LOG WinCE prior to did not require the last parameter in above line. Versions starting with calculate this parameter based on coordinates provided in that line. Some older maps that may control appearance of symbols by specifying number of expand/contract actions rather than absolute map scale may not display properly.

The parameters starting with “M” described in paragraph above are optional. If the circle / arc unit character is missing, statute miles are assumed. If the absolute map scale parameter is missing, program just counts the number of contract/expand key presses.

The corner coordinates the first 12 parameters correspond to the area displayed when map is first displayed. You can have map features that are beyond this rectangle. Remember that in the southern and east hemispheres sign is important in determining which is minimum and which is maximum. The positional data have to be again given in degrees, minutes and seconds, but these do not have to be integers so you can simply set minutes and seconds to zero. Otherwise conventions are as for the waypoints file. Typically you will want to have the min/max settings such that they  do not encompass all the points on the map. As the map moves, new points will show up,  you can  change the scale of the map using “+’ and “-“ buttons.

It is fairly important that you have the area initially displayed reasonably small (less than about 150 miles in diagonal). That is because this establishes some one time scaling parameters. If your initially displayed map area is as big as the whole United states you will notice scaling discrepancies in drawing arcs and circles.

The following lines contain map information:

123.3Mhz\Nice airport in the desert

Above lines place symbol number 1 at latitude 35deg52.5' N and longitude 119deg 42' 0" and label it underneath with a legend "Airs".  “\” as the first character of a legend attaches following line as a note for the symbol.  “\” in comment line is interpreted as "start new line" formatting. Note line should be no more than 254 characters long.

If you do not want a label to appear you must put a comma in it's place, e.g.:

39,49,10,120,21,0,4,,  would place symbol # 4 at the location of Nervino airport, but not label it.

 If requested symbol number is unavailable, you get the default symbol (a square);

Negative (and zero) symbols cannot be followed by a legend. Symbols less than -10 are used to plot in-flight waypoints without legends. They can be also added as regular symbols, but without legends.

Symbols in the range of -10 and -5 are currently neglected, and lines are drawn with symbols in the range of -3 to 0.Two types of lines can be drawn. Course line - which is a continous,wide dashed line, and random solid lines. Symbol -4 is used to draw arcs.

Including map files

If you start map line with a "?", whatever follows will be interpreted as a name of an included map to be found in the same directory as the main map. The included map has to be a complete GPS_LOG WinCE map. 


will attempt to load CrazyCreek. map from a ccs subdirectory of the directory in which the main map is located.

If an included map in turn includes other maps it has to provide names referenced to the directory of the main map. So if the included ccs\ included which resided in the ccs folder, it would have to include it as ?ccs\

Making symbols into selectable waypoints:

If you add altitude information to the label of a symbol (greater than 0) then clicking in its vicinity will result in two buttons showing up. This works only for symbols contained in the main map, not in an included map.

First will display needed altitude and symbol label for up to four symbols, the second "Cancel". Clicking on the first one will result in adding the waypoint you click on  to the destination list. If the program has not acquired GPS fix (it needs to know current position) two question marks will show up instead of needed altitude. If there is a note attached to the symbol its window will be cleared once one of the buttons is pressed. Notes for different symbols are identified by "**" followed by symbol name or question marks if there is no symbol label. Notes for restricted airspace will follow notes attached to symbols if any are found.

In order to add altitude information enclose altitude in between "^" characters at the beginning of the label string (but after the note character "\"). Altitude information has to come before any circle data.

123.3Mhz\Nice airport in the desert

In the above examples altitude for Minden (Mndn) is given in meters. all others are in feet.

Controlling appearance of graphic elements depending on map scale: 

There are two methods to control graphic elements appearance on display. One, local, applies only to symbols (symbol number >0). This method is described in detail first below. Second method is global and applies to all elements other than the ones for which it was overridden locally. The global method description follows the local one.

Local Method:

Following the label you may add information as to whether the symbol will be displayed or not depending on the current scale of the map. You have to provide four coma separated numbers. First number corresponds to the minimum scale distance at which symbol is shown, the second to the maximum. The third and fourth number do the same for symbol legend. Legend is not displayed if the symbol is not.

If the first line were


 and the expansion factor was 1.6 then


would cause symbol for Minden to be displayed only at the original map scale (number of contractions=number of expansions), but the legend would never be displayed. Scale of the map is computed, as you press the expand and contract buttons.

Circles around symbols are drawn according to the global graphic element appearance setting.

Global Method:

Inserting line starting with "*" defines the minimum and maximum map scale state bounding appearance of all graphic elements following that line. The only exception being symbols overridden locally as above and those coming from binary maps. A typical control line may look as:


Meaning of the four numbers is identical to the ones for local control method.

Text Label symbols:

You can put text on a map as map symbol. Text is drawn with the same font and size as symbol legends. Use -5 for symbol number and follow it with a symbol legend (like other map symbols). Legend text becomes the label centered around the symbol location. You can create multiline labels by embedding "\" characters in the text. They become line breaks. No comments can be attached to a text symbol (overlay it with a user defined transparent symbol if you have to have one). Line break character ("\") should not be placed as first character (unless you want it visible). 

39,7,0,120,3,0,-5,This is\Lake Tahoe

Generates a two line text label in the center of  Lake Tahoe on a map. Text label should not be longer than 254 characters.


In order to draw circles of default radius around a symbol, place periods as the first characters of a legend, e.g.:


will place one circle around Alpine and Carson airports (Carson is not labeled just symbol #2), and two circles around Bridgeport.  

You can also draw circles with arbitrary radius around a symbol with, or without circles of predetermined radius. The format for this is to enclose the value for the radius in miles between characters "@" and "M" and place them AFTER (or instead of) the periods (both of which come AFTER the comment character ”\”). You can have multiple circles. The limitation is that from the first "." or "@" you can have no more than 37 characters on a line. Here are a couple of valid examples:  

On a high plateau\hard to see

20 (default) and 50.5 miles radius circles around Alpine. Note the comment character and the comment following on the next line.


30 and 50.5 miles radius circles around Carson with no legend. Note that the "M"s in line above are just delimiters (they must be "M"s). If you want circle radii to be in other units, change the first line in map file (see above).

You can draw circles which are filled, with or without border and with or without symbol. In order to do that use the following format:


the first number after @ is still the radius, the second specifies color of the fill (0 means no fill). Making the radius negative eliminates display of the symbol (and legend). Making the fill color negative results in a borderless circle. The third number indicates color of the circle border. Make it negative to get a wide border. Absolute value of colors is mapped as in the case of user symbol transparent colors. 

Circle border can also be drawn with dashed line. Circle border color needs to be in the range of 17 to 32. In that case subtract 16 from border color to get color mapping value. Dashed circle borders can be drawn only one pixel wide. This is true also for VGA screen devices regardless of resolution setting.

You can also draw circles with arbitrary fill color. In order to do that use  fill color greater or equal to17 or less or equal to -17 and follow the line color by a red, green, blue RGB values in the range of 0-255, e.g:


generates a cyan filled circle with red line boundary.

Circles with fill color 17 or -17 are placed on the topography layer and are drawn before restricted airspace and other map objects.

Note: placing circles with fill color of +-17 in the topography layer started with program version You may find some older maps which do not take this into account.

Starting with program version circles can have translucent fill colors by adding a fourth color parameter after RGB value. For more details see description in the Lines and Polygons section

Lines and polygons:

To draw a course line you define its vertices using symbol #0 (no legend follows) e.g.:


 would make Nervino to be one of the course line vertices.

 !!!! NOTE:

You should not add course line definition to your map, unless you want it to appear always.  Use the “Make Task” capability of GPS_LOG WinCE  instead.

For the other lines symbol "-2" is used to start a line. Symbol "-1" results in a thin line drawn to the defined point from the previously defined point and symbol "-3" results in a heavy line.

38,1,0,118,16,0,-1     - no points previously, so start
39,49,10,120,21,0,-1   - draw a thin line to here
38,12,50,119,0,40,-3   - draw a thick line to here
38,15,40,119,13,20,-2  - start a new line from here
39,49,10,120,21,0,-1   - draw a thin line to here   

Line drawing can be changed to filled polygon by attaching color information after the "-2", e.g.:

38,15,40,119,13,20,-2,3  - start a new polygon fill with color 3 mapped as in case of user symbol transparent colors.

Each filled polygon must end with a "-2" symbol line. This can be used to start another polygon, or another line on a map. If you want a borderless polygon, make the color number negative.

Lines can be drawn with different pen types,

39,49,10,120,21,0,-1,14   - draw a thin line to here with narrow red pen
39,49,10,120,24,0,-1,-14   - draw a thin line to here with narrow dashed red pen
39,49,50,120,24,0,-1  - draw a thin line to here with narrow dashed red pen  (narrow pen type remembered)
38,12,50,119,0,40,-3,16   - draw a thick line to here with a magenta pen

colors are mapped as in case of user symbol transparent colors. For narrow lines (symbol -1) negative color means a dashed pen, for wide lines (symbol -3) negative color is the same as positive. Pen types are remembered separately for narrow and wide lines. They are reset to the standard narrow black pen by any line with symbol -2 (start new line).

If the absolute value of fill color is set to a value greater than 16, then the program requires you to define the color yourself with three numbers following meaning red, green, blue components in the range of 0 to 255. In addition if the absolute value of the fill color is 17, the polygon created is added to "topography set of objects" and is drawn before restricted airspace and other map objects. If the absolute value of the fill color is 27 then polygon is added to permanent overlay layer that is drawn after topography and alarm objects layer. for more information see overlays in this document.


would create a greenish polygon without border that would be added to topography set.

Starting with program version program supports "transparent" fill colors. After color definition add a "fourth number" in the range of 1 to 7. This number has following meanings:

1    fill is hatched with horizontal lines
2    fill is hatched with vertical lines
3    fill is hatched with diagonal lines  \\\\\
4    fill is hatched with diagonal lines  /////
5    fill is hatched with cross lines
6    fill is hatched with diagonal cross lines
7    fill is transparent solid color

-47,12,15,-167,39,44,-2,99,52,199,55,7 creates a greenish polygon that will be somewhat "transparent" to underlying shapes.

When using "transparent" colors make certain that you are not using saturated colors, but "pastelles" that contain all colors to some degree. Overlaying saturated red on saturated green or blue would produce black.

You can make an arc part of a polygon. Follow the format for the arcs, but replace symbol "-4" with "-6" and make certain to use clockwise and counterclockwise arcs when appropriate. If a "-6" symbol is encountered before a polygon is specified, it starts a new unfilled polygon.


To draw an arc with a center at a given location you use symbol -4 and follow it by format similar to that of drawing arbitrary circles. In order to embed an arc in a polygon, replace symbol "-4" with "-6". The information is of the form:

@ radius (in Miles), start angle, end angle, pen color M (no space before M).

 e.g.: 39,52,30,119,42,0,-4,@20.,280,230,-16M@35.,180,100M

In the example above two arcs are drawn around Air sailing. The first of radius 20 miles starting at 280 degrees (true) from Air Sailing, and ending at 230 degrees (true) and is drawn with a wide magenta colored pen. The second has 35 mile radius going from 180 to 100 degrees.  The limitation is that from the first "@" you can have no more than 38 characters on a line. Pen color is optional and is mapped as in case of user symbol transparent colors.. negative color means wide line.

Arcs can also be drawn with dashed line. Line color needs to be in the range of 17 to 32. In that case subtract 16 from border color to get color mapping value. Dashed arc lines can be drawn only one pixel wide. This is true also for VGA screen devices regardless of resolution setting.

Arcs using "@" are drawn counter clockwise. In order to draw a clockwise arc use "#".

e.g.: 39,52,30,119,42,0,-4,#20.,230,280,-16M#35.,100,180M

Note that the "M"s in arc definitions above are just delimiters (they must be "M"s). If you want circle radii to be in other units, change the first line in map file (see above).

There is an alternative way to define arcs in terms of arc center and end points. This was introduced in program version maps using this arc format will not be read correctly by earlier program versions.

The format is as follows:

center coordinates, arc symbol (-4 or -6), & (clockwise ) or $ (counterclockwise), start coordinates, end coordinates, pen color M  .

e.g:   43,39,35,-7,13,28,-6,&43,42,03,-7,50,31,43,13,06,-7,20,44,5M

Only one arc can be defined per line using this format. Be careful using this format when including arcs in outlines of alarmable airspace which you expect to enlarge. You should never include arc end points at line points preceding and following the arc.

Definition as :


may lead to problems (airspace will shrink rather than expand) in enlarging the space due to lack of precision in coordinates definition. Program tries to eliminate these problems, but it cannot be guaranteed that it will succeed.

Above caution applies to arcs defined with @ and # as well, It is advisable to shorten these  if end points are present in the file.

All these can be freely intermixed, but for the lines being drawn in the order that points appear. The lines below are an example of an intermixed set of commands.

Note: Filled shapes (circles and polygons) cover anything that was displayed before them, so put them at the beginning of a file.


Note: Drawing arcs is time consuming. This program is optimised for real time use and displaying maps at reasonable scales. If you zoom out a lot (e.g. display all of United States) you may find that arcs are somewhat rotated from where they should be. If the initial display area is too large you will also find that the radii are not quite correct when you zoom in.

Restricted airspace

Upon entering a restricted airspace an alert sound defined by GPSLG!LT.WAV file is played (but see below) and an [Alarm] indicator button shows up on screen. In order to define restricted airspace enter a line defining symbol "-7" with following format:


In some cases restricted airspace tops and bottoms are specified in AGL. For use in the program you still need to provide absolute top and bottom as above, but you can also include AGL information to be displayed in a note shown when alarm sounds or you click on the map. This information will also be used to generate alarms if AGL altitude information is acquired by program. Format is as follows:


If you use feet, replace M above by coma. If information on one or the other level is not AGL use "-1" in appropriate field, e.g.:


Above line would create a following note "Alt: 1000-8000f (500,--)". Information in parentheses (if present) refers to AGL.

Replacing coma preceding the AGL with H suppresses appearance of the alarm zone note when clicking on a map e.g:


In some cases one may want the notes when map is clicked, but no alarm generated when a zone is entered (e.g. glider sectors ). Replacing coma preceding the AGL with A achieves this result e.g.:


Shapes thus defined cannot be enlarged.

The next circle or polygon or multipoint line defined after symbol "-7" entry is treated as restricted airspace. Polygon or line does not have to be closed (program enforces closure).  If restricted airspace definition contains arcs, they have to be included in polygons (lines) using the "-6" symbol, or be approximated as a series of points. 

Size of the alertable space is further controlled by the restricted airspace options.

Following is an example of restricted airspace definition.

; Reno Class C




You can customize the sound that is played upon entering an alert zone on a zone by zone basis. End symbol -7 line with '\' character, no spaces following it. Follow it immediately by a line starting with ';' and giving the name of sound file to be played e.g.:

49,53,33,-5,13,25,-7,;4500,0 \

these files need to be placed in the same folder as the current alarm default sound file (GPSLG!LT.WAV). If specified file is missing, no sound is played.

In addition to the [Alarm] indicator button a note window will appear in the area of destination information display. This note box will disappear in 10 seconds. You can bring it back by clicking on the [Alarm] button. The note contains alarming zone's altitudes information and a user definable note. Note information comes from the legend of the last symbol  defined between the "-7" symbol line and the "-2"  symbol line starting the zone outline. If  restricted zone is defined as a circle (as in the last example), note information comes from the legend of symbol defining the circle ("Rno" in the above example). If you define the note using a text ("-5") symbol, you can hide it from the map by ending it with "#!" (no spaces after these two characters).



39,29,54.9,119,46,5.0,-5,Reno class C#!


would cause "Alt: 7200-8400 ft  Reno Class C" note appear when alarm sounds, but the text symbol would not appear. If the text symbol containing "#!" is not the symbol that ends up defining a note it will still remain hidden.



39,29,54.9,119,46,5.0,-5,This is Reno class C#!
39,29,54.9,119,46,5.0,-5,Reno class C#!


would cause the same note to appear, but both symbols would remain hidden.

Appearance of other note containing symbols can be controlled by controlling appearance by map scale as outlined above.

If a text symbol defines a note for a restricted zone defined as a circle, actual note that is shown comprises of text defined by text symbol followed by new line and information contained in label attached to the circle. e.g.:

39,29,54.9,119,46,5.0,-5,This is class C airspace#!

would  result in:

This is class C airspace

note attached to a circle restricted airspace around a symbol 1 with "Rno" label.

You can also see notes attached to restricted airspace zones by clicking on the zone image. Note will appear in a note window over the navigation information just as in the case of notes attached to symbols If there is no note, only altitude limits will show. Matching of restricted zones to screen clicks is not very precise. Program only checks if you clicked within a smallest rectangle enclosing given airspace it is thus possible to click outside a zone, but still get information attached to it. You can override this behaviour if your PDA is fast enough by checking the "Accurate check" checkbox in the alarm zones options.

All restricted airspace is drawn after topography object set, but  before all other airspace. Restricted airspace is ignored (but is drawn) if program runs into memory limitations.

Note: In the file replay mode it may be possible to miss an airspace alert if you are "flying" fast and have many restricted airspace zones. Airspace detection is a low priority process that constantly yields to more important things.

Polar data file format

Like in the other files, format is not forgiving. Typical file may look as follows (explanations follow):

DG 101 polar data, low wing loading, up to 100 kts, no data at higher speeds
1,8,42   (no comas beyond here) change the first number to 0 1 or 2 if you want different fit weighting; commas must follow numbers (leave a space after the last number)
Program does the rest

  3 calculated coefficients-high order first
calculated coefficients-end
Fit Results:
speed   sink   L/D
 40.0,  1.02,  39.2
 45.0,  1.14,  39.5
 50.0,  1.29,  38.8
 55.0,  1.47,  37.4
 60.0,  1.69,  35.4
 65.0,  1.97,  33.1
 70.0,  2.29,  30.6
 75.0,  2.68,  28.0
 80.0,  3.13,  25.5
 85.0,  3.66,  23.2
 90.0,  4.28,  21.0
 95.0,  5.00,  19.0
100.0,  5.82,  17.2
105.0,  6.77,  15.5
110.0,  7.84,  14.0
115.0,  9.05,  12.7
120.0, 10.41,  11.5
125.0, 11.94,  10.5
130.0, 13.65,   9.5
135.0, 15.55,   8.7
140.0, 17.67,   7.9 

sink  wind=0 wind=10 wind=20 wind=-15
  1.1   42.0   46.7   51.1   42.0
  1.6   49.2   52.6   56.4   45.2
  2.1   53.7   57.2   60.9   49.7
  2.6   57.5   60.9   64.0   53.3
  3.1   60.7   64.1   67.3   56.5
  3.6   63.5   67.0   70.1   59.3
  4.1   66.0   68.9   72.6   61.8
  4.6   68.3   71.2   74.9   64.1
  5.1   70.5   73.3   77.0   66.2
  5.6   72.4   75.2   79.0   68.2
  6.1   74.2   77.0   80.8   70.0
  6.6   75.9   78.7   82.5   71.7
  7.1   77.5   80.4   83.5   73.3
  7.6   79.1   81.9   85.0   74.9
  8.1   80.5   83.3   86.5   76.3
  8.6   81.9   84.7   87.8   77.7
  9.1   83.2   86.0   89.2   79.0
  9.6   84.5   87.3   90.4   80.3
 10.1   85.7   88.5   91.6   81.5
 10.6   86.9   89.7   92.8   82.6
 11.1   88.0   90.8   93.9   83.8
 11.6   89.1   91.9   95.0   84.9
 12.1   90.1   92.9   96.1   85.9
 12.6   91.2   94.0   97.1   86.9
 13.1   92.1   95.0   98.1   87.9
 13.6   93.1   95.9   99.0   88.9
 14.1   94.0   96.8  100.0   89.8
 14.6   94.9   97.8  100.9   90.7
end results

First line is a comment line. You can put anything that is meaningful to you. This comment line is followed by a line which has to start with either 0,1 or 2 (weight exponent) followed by a coma and an optional value for the speed below which no altitude computation is done and "NO GO" is displayed  (default is 5 kts), followed again by coma and the minimum sink speed, and followed by coma and a number 0,1 or 2 denoting speed units. The speed units number defaults to 0 if missing. Additional comment can follow speed units. There should be no comas in the comment followed by a number if there are fewer than four data numbers at the beginning

Speeds in this line should be in units defined by the units number. Weight exponent changes the way the polar curve coefficients are calculated. 0 gives equal weight to all points, 1 and 2 progressively give more weight to low speed data. Speed units number is translated as follows (anything else defaults to 0):

  number in file speed units  sink speed units
0 kts kts
1 kts ft/s
2 kph m/s

This line is followed by pairs of:

    speed, sink speed - in specified units

coma or space delimited. You need at least 5 pairs (more is better computer will complain with less than 4). These are used for developing a polynomial fit to predict the sink rate at any  speed.  You need to follow the last pair by any comment line.  

For cosmetic reasons you should add a "Done with data" line after  the data pairs.

Computer fills in the rest each time the data is processed. This information is there for you to know what to expect. I'd suggest you run the program once after creating the polar data, and look at the results before using it in flight.

Note that as in the example above, the program does not know about stalls. Therefore L/D estimated at low speeds is overly optimistic.  

Task file format.

Task files are UTF8 encoded files. In many cases there are no differences between an ASCII file and UTF8 one. If you want to assure that no character conversion is done place a comment line ";ASC" (no quotes) at the very beginning of the file

GPS_LOG WinXX support multiple tasks per file. File format is shared with Flight Display and Flight Analysis programs. The latter supports only one task per file. Neither Flight Display nor Flight Analysis support images and sounds sections. A task on file looks typically as follows :

04 CGC,41.431950,0,0,88.245834,0,0,650
34 Streator,41.128334,0,0,88.801666,0,0,653
30 Pontiac,40.923618,0,0,88.625549,0,0,659
09 Dwight,41.133335,0,0,88.440834,0,0,632 
34 Streator,41.128334,0,0,88.801666,0,0,653
27 Ottawa-Old,41.364716,0,0,88.856384,0,0,615
04 CGC,41.431950,0,0,88.245834,0,0,650
04 CGC - takeoff site,41.431950,0,0,88.245834,0,0,650 
04 CGC - landing site,41.431950,0,0,88.245834,0,0,650
1,Watch for glider traffic from opposite direction 
1,Get ready for\FINAL GLIDE 

1,\Storage Card\sounds\pontiac.wav


The "zones", "notes", "images", "sounds" and landing and takeoff sites are optional. However you have to have "zones" section to have "notes", "images",or "sounds" . In the zones , notes, images and sounds sections, first entry corresponds to takeoff point if that is present in a task. Detailed explanation follows: 

File is coma delimited. Comas HAVE to follow numbers with no spaces. 

Line 1: /*TASK*/ - delimiter for tasks 
Line 2: name - unique name given to a task, cannot be duplicated within the same file 
Line 3: color - for use of Flight Display only 
Line 4: nTskP, nExtra, nZones 
                - nTskP is the number of task points (gates and turnpoints), 
                - nExtra number of extra takeoff and landing points. Can be 0,1,2. 
                        There can be no landing site if there is no takeoff site. 
                        This parameter does not have to be included if there are no zones, 
                        nor takeoff/landing sites. 
                - nZones number of observation zones. has to be nTskP+nExtra if present 
Lines 5-x: name,latDeg,latMin,latSec,lonDeg,lonMin,lonSec,elevation 
        - elevation is in feet and is optional. 
        - Longitude is positive in the West. To indicate East make ALL lonXXX fields negative or zero.
                Alternatively, to indicate East make ONLY lonDeg negative (even if zero).
                    The latter is compatible with Flight Display program.
        - Latitude is positive in the North. To indicate South make ALL latXXX fields negative or zero. 
                Alternatively, to indicate South make ONLY latDeg negative (even if zero). 
                    The latter is compatible with Flight Display program.

Line x+1: \*zones*\ - delimiter 
Line x+2: nZones - number of observation zones, the same as in line 4. 
Lines x+3 - y 
        isGate 0 or 1, or 2 or 5;  2 is for finish gate (but 1 is acceptable),  5 is for start gate with an inverted cylinder
        isTurnpoint 0 or 1 or 3; 3 means that this is a checkpoint.  
        hasCylinder 0 or 1, 
        hasSector 0 or 1, 
        cylinderRadius in km, 
        sectorRadius in km, 
        isTurnArea 0 or 1 indicates that distance can be maximised at this turnpoint, 
        sectorAngle full angle in degrees, 
        sectorDirection sector bisector direction (into the sector), or flight direction for a gate,
        minimum sector radius in km;  requires hasSector to be 1 and hasCylinder to be 0
        turnpoint goal longitude,
        turnpoint goal latitude,
        turnpoint goal elevation in feet (in meters if terminated with M e.g.: 234M )
Line y+1 
        startGateTop in feet MSL, startLineLength in km, finishLineLength in km, startHasLine 0 or 1, finishHasLine 0 or 1

Line y+2 : \*notes*\   delimiter for turnpoint notes
Line y+3 : number of waypoints (same as number of zones), number of waypoints with notes.
Line y+4....i :
        0 - no note attached
        1,note   note has to be in one line. Use the \ character to force line breaks in notes when displayed.

Line i+1 : \*images*\   delimiter for turnpoint images
Line i+2 : number of waypoints (same as number of zones), number of waypoints with notes.
Line i+3....k :
        0 - no image attached
        1,image file name.    There has to be no space between coma and the file name.
                        File name is relative to the directory containing the GPSLG!LT.WAV
                        zone alert sound unless it starts with '\'.

Line k+1 : \*sounds*\   delimiter for turnpoint images
Line k+2 : number of waypoints (same as number of zones), number of waypoints with notes.
Line k+3....k :
        0 - no sound attached
        1,sound file name. There has to be no space between coma and the file name.
                        File name is relative to the directory containing the GPSLG!LT.WAV
                        zone alert sound unless it starts with '\'.

Track color file format

This file consists of first line being an information line and a set of 21 triplets giving colors in Red, Green, Blue format. Each number should be between 0 and 255. Delimiting comas have to follow number without any space. File has to end with a blank line. First triplet is for sink rates greater than 9.5knots, last number is for climb rates greater than 9.5knots. Colors change in 1knot (0.5m/s) steps. This may change in the future to emphasize changes near the center of the band, but there will not be more colors. Program uses default set of colors if the color file is absent. File included in the distribution package (not the default colors) looks as follows:

Red, Green, Blue 0-255 21 triplets, -10knots to 10 knots Track color table for GPS_LOG WinCE ;































































































































































































































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