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GPS EGNOS Report
This report illustrates my first experience using WAAS/EGNOS with my Garmin GPS V.
What is WAAS/EGNOS?
Ground reference stations are calculating the data required for each GPS satellite to improve the positioning and transmit it via satellite to all users for free. WAAS/EGNOS enabled GPS units receive and use this data and can then improve their position accuracy to less than 3 meters. Find more information about WAAS here.
What Hard- and Software was used?
My Garmin GPS V was updated (using Webupdater) to GPS V Ver. 2.50 (2003-10-09). Pictures from the device display are generated by xImage from Garmin. Read more about my mobile APRS station on the page about HB9SQX-9.
Positioning using WAAS/EGNOS
Report date: January 3rd, 2006.
After turning on the GPS V the position was determined without WAAS/EGNOS. The device was used within a car with roof-mounted active antenna from Lowe. The sky around the location was free and with especially low horizon to the south. Thus, a good signal could be expected from the EGNOS satellites. Actually, the position accuracy of 5 meters wasn't bad at all.
As expected, the EGNOS satellites with Garmin ID 33 and 39 were in view. I expected good signals and switched on the WAAS option.
Just a few seconds later, the device indicated with the letter "D" the reception and use of DGPS data for some satellites. You have to be quick at shooting the hard copies of the GPS device with xImage if you want to document the process of improving accuracy, going down to 4 and 2 meters.
And what happens when WAAS is switched of again? Expecting a raising position error was wrong: it remained as low as 2 meters even while driving aroung (the signals of the satellites altered, but the position error not). Is the GPS device still using the DGPS correction data?
