Experimental avionics




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    GPS Module


Requires: GPS

GPS summary in flight

GPS summary in flight

This application displays a summary of the current GPS data. The lines on the screen show:
  1. the latitude (in degrees)
  2. the longitude (also in degrees)
  3. the altitude (in metres)
  4. the bearing reported by the GPS device, and the ground speed (in knots)
  5. the ‘dilution of position’, horizontal and vertical – this is an estimate of the accuracy of the GPS fix; in practice a dilution of 1.0 seems to correspond to about ten metres
  6. a status line
    • the four characters on the left indicate the quality of results; AAA3 means all data are good
    • the 09 indicates that 9 satellites were being received
    • the 94457 is the time of day, UTC (09:44:57).

Theory & practice

This is the simplest application as it is only displaying information provided by the GPS module; no calculations are required.

The GPS module is set up to return three of the possible NMEA sentences available:

  • RMC (Recommended Minimum Specific GNSS Data) at 10Hz
  • GGA (GPS fixed data) at 10Hz
  • GSA (GNSS DOP and Active Satellites) at 1 Hz

After each sentence is received it is parsed and its data values are saved.

  • RMC provides time-of-day, status, latitude, longitude, ground speed, bearing, and date
  • GGA also provides time-of-day, status, latitude, and longitude, and in addition the satellite count, horizontal dilution of position, and altitude
  • GSA provides status, identifiers of up to 12 active satellites, and three dilution of position numbers (total, horizontal, and vertical).

The GPS summary screen simply displays a selection of the data received.

This website is compiled and maintained by Mike Cowlishaw; Please send me any corrections, suggestions, etc.
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This page was last edited on 2010-09-12 by mfc.