- - - - - - - - - - - - - - - - - - Short description of the event: On 7-mar-98 between 21:11:57 and 21:31:46 I noticed GPS anomalies that I've never seen before. These anomalies resulted in position errors in latitude, longitude and altitude up to 600 meters. I have data to support the event in the form of track and waypoint files recorded by pcx5 downloaded after the event from a Garmin 45. I'm interested whether the event was local because of RFI or global because of a GPS problem. Long description of the event: The event started around 21:11:57 GMT where the G45 displayed the message "power down and re-init" which according to the manual refers to a situation where the GPS 45 is not able to calculate a position due to abnormal satellite conditions. The manual suggests to turn the unit off and to verify the last position by other means. I did this several times and it didn't help. I tried several modes (normal and autolocate), in both cases the GPS 45 reinitialized itself, appeared to be running for a minute or so and came back with the same messages. Eventually I ran a self diagnostics test (enter/on simultaneously). The GPS 45 did not appear to complain about anything abnormal during the diagnostics. At 21:31:46 things went back to normal and the receiver operated as usual. The track file that I've downloaded from the receiver (0710398.trk) shows errorneous position readings from a car on the interstate between Antwerpen and Breda. The North to South track along that interstate was recorded in the morning where everything seemed to be ok which I can tell because I've driven this part many times. Earlier I've recorded waypoints which are stored in the file 0710398.wpt. The morning track ran nicely through the waypoints. The evening track goes South to North along the same interstate. For most part you can see that the tracks run parallel. This is not anymore the case near the locations where the receiver started to display the "power down and re-init" messages. There is evidence for this between 21:11:57 and 21:18:02 GMT and also between 21:24:16 GMT and 21:24:29 GMT. - - - - - - - - - - - - - - - More at: Report: http://pocus.geo.tudelft.nl/~schrama/Public/gps/g45/anomaly.txt Track file: http://pocus.geo.tudelft.nl/~schrama/Public/gps/g45/0710398.trk RF Jim ----- Original Message ----- From: "Chris Loiacono" To: Sent: Tuesday, November 19, 2002 3:38 PM Subject: Re: [OT] While on the subject of GPS... > Does the error of a standard GPS receiver affect it's ability to determine a > vehicle's or vessel's speed accurately, or is it safe to assume that the > error will be constant and the speed it reports will be accurate? > > TIA, > Chris > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics