GNSS interface problems

RE: GNSS interface problems

kclauah — Wed, 17 Nov 2021 04:14:16 GMT

Thank you!

My board is connected with a patch antenna and try to retrieve location sitting next to the windows but it is not working. A GPS repeater maybe a bit overkill. I have also tested cellular based location service but the result is unacceptable(I have not tried the new location API, but using GetSingleCellLocation).

Let me take a look into the master branch location API and see if porting the GPS simulator is feasible.

RE: GNSS interface problems

Didrik Rokhaug — Tue, 16 Nov 2021 10:35:42 GMT

[quote user="kclauah"]Or in any way I can test the GNSS interface indoor?[/quote]

You could use an external antenna, or a GPS repeater, though both of those solutions might be a bit over the top if you are not testing the GPS specifically.

[quote user="kclauah"]But is there any chances I can port the code of GPS simulator to GNSS interface?[/quote]

Yes, you might be able to do that. But you risk running into problems with multiple definitions of the API.

Another solution would be to use the new location API which has been included on the master branch: https://github.com/nrfconnect/sdk-nrf/blob/main/include/modem/location.h

It will support both cellular and GNSS based location backends. The cellular based location services might be a good enough solution (no need for simulating anything, but some potential cost on the cloud side), or you could port the simulator to use the location API.

RE: GNSS interface problems

kclauah — Mon, 15 Nov 2021 01:53:25 GMT

The GNSS interface does not support simulating GPS data.

The GPS simulator isn't removed yet, but with a different API it probably isn't as usefull.

Thank you for your response. I have tested the board outdoor which has a fast first-time-to-fix and great accuracy in positioning. But is there any chances I can port the code of GPS simulator to GNSS interface? Or in any way I can test the GNSS interface indoor?

It is hard to find a place which is outdoor and has a table and chair in my area. A rainy day/days make the problems worse.

2. To save power, the GNSS can keep sending 1PPS using an on-board timing source, instead of keeping the GNSS running at all times.

The setting should not have any effect when not using 1PPS.


3. You need to call nrf_modem_gnss_start() before you call nrf_modem_gnss_dyn_mode_change().

Also, remember that GNSS must be activated in the modem, with AT+CFUN=1 or 31.

Thank you for the clear explanation.

RE: GNSS interface problems

Didrik Rokhaug — Fri, 12 Nov 2021 10:12:52 GMT

Hi,

[quote user=""]1. GPS driver can generate simulation data, how can I do the same in GNSS interface?[/quote]

The GNSS interface does not support simulating GPS data.

The GPS simulator isn't removed yet, but with a different API it probably isn't as usefull.

[quote user=""]2. GNSS interface can select Timing source between RTC and TCXO. If I am not using 1PPS, is there any beneficial in 1 minute periodic navigation?[/quote]

To save power, the GNSS can keep sending 1PPS using an on-board timing source, instead of keeping the GNSS running at all times.

The setting should not have any effect when not using 1PPS.

[quote user=""]3. In GNSS interface, there is a chapter called changing-the-dynamics-mode. But it does not work when I testing in GPS example.[/quote]

You need to call nrf_modem_gnss_start() before you call nrf_modem_gnss_dyn_mode_change().

Also, remember that GNSS must be activated in the modem, with AT+CFUN=1 or 31.

Best regards,

Didrik