This tag refers generically to *any* space-based satellite navigation system that provides location and time information.

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11
votes
5answers
9k views

Convert XY points to a line?

Someone mistakenly saved a GPS track as waypoints and then sent them along to me in a .csv file. They want a line back (shapefile). What's the simplest method to convert this to a line? Available ...
2
votes
4answers
135 views

Where to license non-automotive POIs for France, Spain and Portugal?

qualified POIs are needed for a commercial project - should cover broad out-of-car usecases (not needed: parking, gas stations). Could be commercially licensable data or derived from national geodata ...
5
votes
1answer
1k views

Calculating absolute precision confidence number from Dilution of Precision indicators from GPS receiver

End-user GPS receivers typically show an absolute confidence indication, such as Within 25 Metres, for the calculated position. I am parsing NMEA data from a GPS unit and wan't to calculate a similar ...
19
votes
6answers
3k views

Is GPS more accurate on specific hours of the day?

I have heard that the GPS system is more accurate, and less accurate on some specific hours on the day. If this is true, how can I get the information on when GPS is more or less accurate at my ...
7
votes
4answers
3k views

What data is sent from GPS satellites to receivers?

I know more or less how the GPS system works. But I would like to understand it in more details. Exactly what data is sent from a GPS satellite to a GPS receiver? I think there is multiple types of ...
22
votes
4answers
29k views

What are the major differences between GPS, GLONASS and Galileo?

What are the major differences between GPS, GLONASS, COMPASS and Galileo?