nRF9160DK v0.9.0 GPS Issue

RE: nRF9160DK v0.9.0 GPS Issue

Didrik Rokhaug — Tue, 28 Jul 2020 08:11:25 GMT

Great to hear.

If the problem is limited to just that one DK, I don't think a modem trace is necessary at this moment.

Best regards,

Didrik

RE: nRF9160DK v0.9.0 GPS Issue

gscultho — Mon, 27 Jul 2020 22:22:43 GMT

Hi Didrik,

I tried a new board (same hardware version) and did not see the same issue, so I assume it was specific to that one board. I can still take modem trace if desired, but this issue is resolved on my end.

RE: nRF9160DK v0.9.0 GPS Issue

Didrik Rokhaug — Mon, 27 Jul 2020 08:27:07 GMT

Hi, and sorry for the late answer.

Could you take a modem trace?

That would let us see what is happening on the modem side.

I have seen similar behavior when LTE was running in the background (no PSM or eDRX, but no user data sent or received either). This only allows the GPS to run for very short periods of time between the Paging Time Windows, which didn't seem to be enough to allow a fix. The positioning of the device didn't help much either, as it was indoors with poor view of the sky. But, as the GPS sample does not activate LTE (unless using AGPS), I don't think that is the problem in your case.

Best regards,

Didrik

RE: nRF9160DK v0.9.0 GPS Issue

gscultho — Tue, 21 Jul 2020 15:24:46 GMT

Hi Didrik, thanks for the response.

Allow me to clarify. Any sample project I have tried that uses A-GPS to start the GPS works as expected using modem FW v1.2. So, "asset_tracker" and "nrf_cloud_agps" both work as expected and are able to achieve both LTE and GPS operation using modem FW v1.2. However, when trying to use the GPS without A-GPS ("gps" sample, for example) with modem FW v1.2, a GPS fix is never achieved. About 10 satellites are tracked, but zero used and no fix. The "gps" sample begins to work correctly simply by changing modem FW from v1.2 to any previous version.

I have just tried to run the "gps" sample with ncs v1.2 and modem FW v1.2, and the problem persists. The GPS tracks many satellites but achieves no fix with modem FW v1.2 flashed. As soon as I flash modem FW v1.1.3 or any other and reset the board, the GPS achieves a fix in under 30 seconds.

To directly answer your questions:

- The slow connection time occurs every time with modem FW v1.1.3, and PSM is usually denied as well (it is always accepted with FW v1.2).

- The problem persists with ncs v1.2.

- My team has another DK that I can try but they are all v0.9.0.

- I am using the included Molex antenna. SW12 is switched to "CON".

I have not tried the command AT+CFUN=0 but will do so and see if it improves performance when using modem FW v1.1.3.

Thank you for your support.

RE: nRF9160DK v0.9.0 GPS Issue

Didrik Rokhaug — Tue, 21 Jul 2020 08:34:37 GMT

Hi.

I am a bit confused about what you are writing. If you are using the "gps" sample unmodified, the nRF9160 will not use PSM, but simply not start the LTE stack. If you modify the sample to use A-GPS, it will still not use PSM, but instead start and stop the LTE stack when fetching the A-GPS data.

[quote user=""]-LTE network connection takes minutes using v1.1.3 as opposed to seconds using v1.2.[/quote]

Does this happen every time you use v1.1.3, or only the first time after v1.1.3 has been flashed to the modem?

One way to speed up the attach sequence is to issue AT+CFUN=0 after attaching. That will store the current network parameters in flash, which can speed up subsequent attaches.

I am not aware of any compatibility issues between mfw v1.2.0 and DK v0.9.0. That combination was tested as part of the release of mfw v1.2.0, and I am not aware of any problems related to the GPS that was uncovered during that testing.

Does it work if you use NCS v1.2.0?

Do you have other DK versions that you can test with?

What GPS antenna are you using?

I do not have any v0.9.0 DKs available at the moment, but the GPS sample works as expected on a v0.8.5 DK with an external patch antenna.

Best regards,

Didrik