BG95 M3 GNSS Error in maintain GPS

Hello everyone, I’m trying to use GNSS over the BG95-M3 module and it did work well after I wait some hours until the module got the signal. My questions is there a way to reduce this time after the module wake up? What time is considered normal? It depends on the quality of my antenna?

The GNSS performance is highly dependent on a few factors.

If you are not seeing any satellites, you may put aside another working GNSS receiver and see if it is the reception environment being too unfavourable. You may need to change the environment or ensure your antenna connection or the antenna itself is good.

If you are seeing very few satellites (below 4) and cannot get a fix, you can re-try with an active antenna.

If you are seeing quite a bunch of satellites but still cannot get a fix, you can re-try by enabling Xtra (AGPS).

To get a fix you need 3 to 4 satellites of CNo no less than 35dBHz. Without Xtra enabled , my fix time is in the order of 45 to 60s for each cold start. However this time is not guaranteed and sometimes I did not get a fix even after 3 minutes. To improve this I enabled Xtra which would always give me a fix time within 15s for every cold start.

Another factor is the constellation you choose to use. In my case if I did not enable Xtra and configured the constellation to be GPS+Gailieo or GPS+Beidou, I would never get a fix no matter how hard I tried. I could only get a fix with GPS+Glonass. However after I enabled Xtra, a fix could be achieved regardless of the constellation configuration.

So write some code, examine the NMEA log and make comparison with other known good GNSS receiver. My ultimate advice is to enable Xtra even if GNSS is working. Xtra really makes a big difference.

@hobby_a Thanks a lot for your detailed advice and precise information. I’ll check what you said and see if I can manage to work.