GPS Accuracy

Adafruit Ethernet, Motor, Proto, Wave, Datalogger, GPS Shields - etc!

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jsluke
 
Posts: 28
Joined: Fri May 06, 2011 5:54 pm

GPS Accuracy

Post by jsluke »

I am using the GPS Logger Shield with a GPS 622R Module ( http://www.rfsolutions.co.uk/acatalog/B ... odule.html ).

The datasheet states that the module has an accuracy of 2.5m.

I'd appreciate any advice on what this accuracy actually means? Is the error systematic or random? If I were to place two (or more) GPS Loggers side by side at the same location will they show the same position or could they show positions up to 5 metres apart? If I leave a GPS Logger at the same location without any motion will it continue to report exactly the same position or will it vary by up to 2.5m?

Am I correct in saying that GPS error is largely the result of propagation errors on the received radio signals, therefore the error should be systematic?

Many thanks.

James.

adafruit
 
Posts: 12151
Joined: Thu Apr 06, 2006 4:21 pm

Re: GPS Accuracy

Post by adafruit »

each module can be different, please contact the manufacturer of that module for detailed information about the specifications - we don't carry that particular one

sbright33
 
Posts: 59
Joined: Thu Sep 01, 2011 3:23 pm

Re: GPS Accuracy

Post by sbright33 »

This discussion is related:
http://arduino.cc/forum/index.php/topic,73379.0.html

10m accuracy is more common among GPS units. If the 2 units side by side were forced to use the same satellites, and the same firmware, they would read the exact same error. It will vary like a random walk. Like a person walking very slowly around within a 10m radius circle. Sometimes crossing the line to the outside. The error has multiple causes.

5m Ionospheric effects
3m Shifts in the satellite orbits
2m Clock errors of the satellites clocks
1m Multi path effect
1m Calculation rounding errors

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