Simple GPS data display programs (limited mapping capabilities)
VisualGPS
Satellite Mapping Software
MapSphere
GooPs (with Google Earth)
The goal here is to find out where the LAST place that your Eggfinder ended up… this is going
to be very close to your actual landing spot, unless for some reason your rocket drifts way out
of range. Even then, you’re going to be able to get an idea of the direction that it was going
before you lost radio contact, so you’re still likely to get your rocket back.
The NMEA-Formatted Data Format
If you’re a software minimalist, you can use a simple terminal program such as PuTTY
(
http://www.chiark.greenend.org.uk/~sgtatham/putty/
) to display the raw GPS data. There’s a
lot of GPS “noise”, i.e. records that you don’t want, but if you simply focus on what you’re
looking for it’s not that difficult to pick out the last received location. First though, you need
to know a little about the NMEA data format.
NMEA (National Maritime Electronics Association) GPS data is a simple text display, with a
number of records that give you information about the location of the GPS unit and the satellite
environment. Realistically, the only records that you need to have are the $GPGGA records:
these are the ones that display latitude and longitude. From gpsinformation.org, a really easy
to understand and well-formatted source on NMEA data formats:
GGA
- essential fix data which provide 3D location and accuracy data.
$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47
Where:
GGA Global Positioning System Fix Data
123519 Fix taken at 12:35:19 UTC
4807.038,N Latitude 48 deg 07.038' N
01131.000,E Longitude 11 deg 31.000' E
1 Fix quality: 0 = invalid
1 = GPS fix (SPS)
2 = DGPS fix
3 = PPS fix
4 = Real Time Kinematic
5 = Float RTK
6 = estimated (dead reckoning) (2.3 feature)
7 = Manual input mode
8 = Simulation mode
08 Number of satellites being tracked
0.9 Horizontal dilution of position
545.4,M Altitude, Meters, above mean sea level
46.9,M Height of geoid (mean sea level) above WGS84
ellipsoid
(empty field) time in seconds since last DGPS update
(empty field) DGPS station ID number
