+M3ZPY Posted June 21, 2005 Share Posted June 21, 2005 Hi, Since I have now got an external antenna and the accuracy is soooo good can any one tell me what the number of each satelite on my screen relates to the satelites hovering above the earth, as I only thought there was 24 but my 60cs seemed to be trying to lock onto a number 49 sat this afternoon. Also how can you tell if the Garmin is benefiting the EGNOS system (I know about the D's for WAAS -that subject is getting old and tiring now ) Link to comment
+Cardinal Red Posted June 21, 2005 Share Posted June 21, 2005 WHAT IS GPS AND HOW DOES IT WORK ? - Courtesy of GARMIN Corporation Excerpt: The pseudo-random code identifies which satellite is transmitting--in other words, an I.D. code. We refer to satellites by their PRN (pseudo-random number), from 1 through 32, and this is the number displayed on a GPS receiver to indicate which satellite(s) we are receiving. So why there are more than 24 PRN numbers? This simplifies maintenance of the GPS network. A replacement satellite can be launched, turned on, and used before the satellite it was intended to replace actually fails! They simply use a different number (again from 1 through 32) to identify the new satellite The above is NOT taking into account WAAS or EGNOS More information covering the higher numbers of Differential GPS The US West Coast WAAS Satellite is #47 The US East Coast WAAS Satellite is #35 It seems that EGNOS Satellite numbers are #33 and #44 Satellite # Garmin The NMEA standard WAAS labels are used by Garmin receivers. This system maps the PRN number to the NMEA label by subtracting 87 from the PRN number. (source: EGNOS help desk) The mapping from the Garmin numbers to the standard names and PRN numbers are: Satellite # ....................Garmin # AOR-E 120 ......................33 AOR-W 122 ......................35 ARTEMIS 124 ................... 37 IOR-W/F5 126 .................. 39 MTSAT1R 129 ................... 42 IOR 131 ........................... 44 POR 134 ........................... 47 MTSAT2 137 ..................... 50 No information about Satellite #49 here. I guess the system keeps evolving. Link to comment
+M3ZPY Posted June 21, 2005 Author Share Posted June 21, 2005 wow thanks for that greatly detailed bit of info - I just could not believe the signal strength when a sat in the 40's showed up this afternoon on my gps but then again I was using an external antenna and the car roof may have been helping a great deal. Link to comment
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