GPS accuracy issue

RE: GPS accuracy issue

Yusuke — Wed, 05 Aug 2020 13:27:36 GMT

Thank you for your advice.

>In general if you want to get a fix within 30 minutes (1800 seconds) which is the maximum fix interval time we support, then we recommend using periodic mode.

There is no option to stop fixing in periodic mode though. It seems that I need to use single-fix mode in my application at this moment.

RE: GPS accuracy issue

Heidi — Wed, 05 Aug 2020 11:27:50 GMT

Hi, on the current MFW there is no noticeable difference between the two.

In general if you want to get a fix within 30 minutes (1800 seconds) which is the maximum fix interval time we support, then we recommend using periodic mode.

RE: GPS accuracy issue

MJD093 — Mon, 03 Aug 2020 08:29:56 GMT

Hi Yusuke,

Can you check the timestamp values for the GPS data points? I have noticed myself when using a GPS interval of 10s, I often receive a result of 15:30:10 for point one, then the next sample read is actually 15:30:11. Might explain a bit of the grouping.

RE: GPS accuracy issue

Yusuke — Mon, 03 Aug 2020 05:37:42 GMT

Hi, may I ask another question?

I would like to get GPS position changing a turn-off period every fix.
I think it is good to use single-fix navigation mode repeatedly, but I'm not sure about the difference between repeatedly using single-fix nav mode and periodic nave mode.
Is there any drawback in using single-fix nav mode instead of periodic nav mode?

RE: GPS accuracy issue

Yusuke — Thu, 30 Jul 2020 13:55:29 GMT

The modem apparently stores GPS position data by FIFO buffer. Fixed position data is not removed unless it is read by nrf_recv. Is this correct?

Enabling single-fix mode by nrf_gnss_fix_interval_t fix_interval = 0 fixes the above issue.