8 years, 10 months ago.

clear previous almanac data

having trouble with my module being about 45 km or 0.7 degree west/negative in longitude. is there a way of resetting it

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8 years, 10 months ago.

I don't have one to test it on but going by the data here you can perform a cold start (erase all almanac, time and clock data) by sending the GPS module the line:

$PSRF101,0,0,0,0,0,0,12,4*<checksum>

Where <checksum> is the 2 character NMEA checksum for the line.

Changing the final 4 to an 8 will also reset the entire GPS to factory defaults. Unless you've done something like change the baud rate the two will probably be effectively identical. Expect it to take a couple of minutes to lock on after you do this.

Having said that you shouldn't need to do this. 45km is not much of an error, it will still be looking for the correct satellites and so that should be good enough to speed up the initial lock on. As soon as it has locked on and is tracking a few satellites it will jump to the correct location.

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