These are general instructions for the use of the GPS track log flight verification system. For more technical, background information, including the cable set-up, refer to the Mac gps page
Waypoints look like:
W START8 INTERSECTION 29/12/1998 00:00:00 55
H 0612000 6295300
Waypoint format is:
W<tab>NAME<tab>DESCRIPTION<tab>DATE<tab>MAPnn<tab>EASTING<tab>NORTHING<cr>
Where....
W.specifies waypoint data to follow.
NAME.is up to six caracters (eg START)
DESCRIPTION.is up to nineteen
characters (eg INTERSECTION)
DATE.is in the format dd/mm/yyyy<space>hh:mm:ss
(eg 28/10/1998 00:00:00).
The Date of the first waypoint (second line of text file) is the
date the task was flown, and all track log data before this date will be
ignored.
MAPnn.is Map Number (eg 56)
MAPa.is Map Letter (eg J)
EASTING.is in metres (eg 0513020 is
equivalent to 513.020km from map)
NORTHING.is in metres (eg 7030421 is
equivalent to 7030.421km from map)
The following images shows the "preferences" options.
To get times and positions for the scoring, the map grid and datum need to be set to match the maps that they relate to. Be aware though, that the features that maps display may change over time and start gates and turn points need to be accurately verified by a GPS on the ground at the feature.
The rules state that if there is a difference between the named feature and the supplied coordinates, the correct coordinates will be found and both positions can be used to verify the flight.
This version of the program gives you options as to what type of sector is used. You can use various "grace" options by checking the appropriate tick boxes. The type of sector that will be used for flight verification needs to be specified before the flight, and of course the program needs then to be configured accordingly and not changed.
Note the option called "Extrapolate Finish Times". This is there because normally a crossing time will be calculated by interpolating the pair of points that cross the goal and then the calculations assume a constant speed in between the two points. In practice, as soon as a pilot crosses the line, their speed will reduce drastically, hence making a small error in the time calculation. This option will cause the finish time to be calculated from the pair of points that cross the line, but the speed will be taken as the speed in between the previous pair of points.
By checking the "Auto Line for Start (or Goal) options, the sectors become automatically generated lines. A user defined start line can be entered manually into the task file.
The screen image can be zoomed in to look at any area of the flight. Here is a close-up of a pilot's start. This pilot did not reach the goal, therefore the lettering is in red and the fact that no finish time has been recorded is noted. The green lettering beside the sector diagram is the time and date of the last point in sector. The (in this case) red lettering is the calculated time that the pilot crossed the edge of sector.
. 
This example shows a track log of a pilot who really cut it fine! The straight lines in between his logged points did not pass through the TP sector, however he circled on the edge of sector and although (by chance) no logged points fell inside the sector, he pressed "MARK" then "ENTER", twice in rapid succession and hence gained a point in sector. Using a smaller track log time interval can fix this problem of not getting logged points where you want them, or you can fly more conservatively into the sector to make sure that you have points logged in sector.
Once an in sector point occurs, line goes green for one segment, then black.
A start gate time is displayed every time the track log goes out of the start
gate sector (this time is displayed immediately beside the point of crossing the
start.)
Once a valid first turnpoint point occurs, or pilot flies 10 km from start point
along course line, then no more start gate times are calculated.
The last start point is used to calculate time across start line.
The first point in goal is used to calculate time across finish
line. No goal times occur before the first turn point, or before the start
if no turnpoints.
To zoom in on a point click on that point.
To zoom out, click on the window zoom box (Small Square in big square, upper
right hand corner)
Program won't always show points either side of sector as good even when joining
line intersects sector.
I always use UTM for task file - haven't tested other formats (eg Lat Long)
Lats and Longs can be used on the pilot's GPS unit for task setting, waypoint
setting, and use by pilots in the air. Time and date settings on the
pilot's GPS are also irrelevant. During flight, the pilot's GPS can be set
for either NMEA or GRMN/GRMN communications.
However, the preferences in VerifyGPS should be set to UTM always, and the
correct time zone set. Also the pilot's GPS unit must be set to GRMN/GRMN
communications for the download.
If Verify from GPS fails, then use
macGPSdmy / Communications Menu / Transfer from GPS Receiver / Track Log
You will then need to view the Track Log from File, so use
VerifyGPS / File Menu / Verify from File
this will verify turnpoints and start time (and goal etc.)
Data in data files can be examined by double clicking them. This will start the Text Editor BBEdit.
To examine a pilots position according to time (in the case of a day being cancelled) the text file of the track log needs to be looked at, and you then scroll down the page until the correct time appears. The track log coordinates that correspond with this time are to be taken as the finish of the flight.
The program does not yet automatically calculate the "best position on course" if this is to be used as the finish of the flight as opposed to the actual landing position. Again, the text file needs to be viewed, and the most appropriate position taken from the coordinates displayed.
If program hangs during Verify from GPS
1. Remove cable
2. Try to quit program from the File menu
3. If that doesn't work try CTRL-ESC to force quit program
4. If that doesn't work try CTRL-CMD-POWER to restart computer
5. After any force quit of program you may need to restart computer to reset
serial port.
CMD key is the one with the cloverleaf and apple on it.
Many menu commands have keyboard shortcuts.
CMD-T Open Task File
CMD-G Verify from UPS
CMD-F Verify from file
The Garmin units are quite secure against people trying to modify track log
data to improve their time or position. Although data can easily be taken from a
GPS and then modified (say on a computer in the retrieve car), when the new
track log is re-inserted into the GPS, all time information is lost (although
the modified position data will be transferred intact). This gives a time for
all points, of 31/12/1989 00:00:00. Any time stamp of 00:00:00 or any odd
looking time should be investigated by looking at the text file for that flight.
These odd time stamps mean either that someone tried to cheat, or there is
something wrong with the unit. In either case the track log should be rejected.
Before any new type of GPS is approved for use for flight verification it must
demonstrate this level of security. The IGC (International Gliding Commission)
have been using GPS flight verification for category 1 competitions for some
years now, and they have developed an elaborate security system. Some of the new
GPS/varios have datalogging features that conform to the IGC standards, and so
are deemed to be secure.
Program by D Tim Cummings
This program is the basis of the turnpoint verification program. It handles
Garmin comms between a Mac and any Garmin handheld (the 90 has some trouble) and
is useful for uploading and downloading waypoints and tracklogs individually. It
is useful if for some reason the main VerifyGPS program won't communicate
properly with the Garmin (pretty rare). It uses very similar file format to
VerifyGPS. The only difference is that waypoints and tracklog are in one file in
VerifyGPS and MacGPS creates two files. There has been some slight mods to the
original (MacGPS) so that it handles Southern Hemisphere coordinates and dates
are in day month year format. See MacGPS Instructions to run this program.
Conclusion
The system has been working very well, and is very popular with the pilots as they would watch each other's "flights" as the computer laid their recorded flight on to the course. The download and verification process is achieved quite quickly. Usually less than one minute per pilot would see turnpoints verified or denied without ambiguity, and start (as well as finish times if wanted) times measured and the information entered into the scoring program.
The software is currently in Macintosh format.
Michael Zupanc-zupy@ozemail.com.au
Tim Cummings- tim@eis.net.au
Oh, and make sure you use correct co-ordinates!