Das GPS System:
The GPS Satellite system is operated from the american ministry of defence and enables worldwide positioning. The signals of min.3-4 satellites are analyzed. In 95 % the mistake in position calculations is about 10-15 m. Athmospheric disturbances and delay changes cause these mistakes. The GPS-system is the basis of all systems, that are presented in this article.
The D-GPS system:
For a local correction of the GPS-position, LW differential transmitters were built along the coasts. With the matching receivers it is possible to get a position accuracy of 3-5 m. The additional receivers are expensive and most systems require fees for the transmission of the signals.With the new systems, D-GPS is no longer needed.
The coverage of the 3 systems
The EGNOS system:
From 2003 on, a correction signal will be radiated from european satellites.It ensbles a position accuracy of 3 m. The signal will be free to use. The frequency is identical with the GPS frequency, so you don´t need additional antennas or receivers.
- a declaration for the EGNOS system
- time table of availability.
The WAAS system:
For the USA the WAAS system, wich is similar to the EGNOS system, is additionally developed.
The MSAS system:
For Japan the MSAS system is developed.
Here you can find a comparison between various GPS-handheld instruments.
These instruments already have a built-in EGNOS and WAAS receiver:
- Magellan Meridian series
- Magellan SporTrak series
- Magellan FX 324
- Furuno GP-32
- Simrad 33er series
- Simrad 42 / 52 Plotter
- Garmin 72, 76er series and 76S
- Garmin GPS V
- Garmin GPSMAP 182 / 182C
- Garmin 2006 and 2010
- Raymarine GPS and Plotter