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  • Case ID: 307480
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Thingy:91 Asset Tracker V2 GNSS doesn't get a fix when connecting to a specific operator

peng.cheng

Hi,

Hope everything is fine with you!

There are three operators covering my workplace,

24007 tele2 --- PSM eDRX good ---
24008 Telenor --- PSM eDRX not supported ---
24001 telia --- PSM eDRX not supported ---

When I say `not supported`, I mean there is output `PSM parameter update: TAU: 3240, Active time: -1`.

I am working with GNSS recently, and found a strange issue,

when the thingy:91 connects to 24001, GNSS will fail to get a fix with a high possibility, around 3/4 GNSS location service fails,

but when thingy:91 connects to 24007, GNSS will always get fixes successfully.

At first, I think it could be that 24001 doesn't support PSM/eDRX, this will affect the GNSS because GNSS shares the same antenna with the LTE-M.

But then I found when thingy:91 connects to 24008, it still can get location fixes continuously and successfully.

I checked the paging time window by using `AT%XPTW?`, it is the same for both 24001 and 24008.

So my question is what is the key point to affect the GNSS function in this case for 24001 and 24008?

Any help will be much appreciated! Thanks!

BR,

Peng

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  • 0

    Hello Peng, 

    With what SIM card are you testing the connection? Are you able to provide the logs from Asset Tracker v2 along with modem traces? 

    Thanks. 

    Kind regards,
    Øyvind

  • 0 in reply to Øyvind

    Hi  ,

    Thank you for your quick reply!

    The SIM card is the iBASIS purchased together with the Thingy:91 board.

    I tested in another place today, on top of an 8-floor building inside of the city. The situation is a bit different,

    when the device connects to 24001, still no GNSS fixes, usually only 1 satellite is tracked.

    when the device connects to 24007, several satellites are tracked, but still no GNSS fixes.

    The attachments:

    trace-2023-05-09T14-23-34.865Z_24001.bin is the trace log when the device connects to 24001,

    trace-2023-05-09T14-27-11.143Z_24007.bin is the trace log when the device connects to 24007,

    thingy91_24001_24007_all_fails_together_with_tracelog.txt is the application log with debug enabled, you can find `AT+COPS=1,2,"24007"`, this is the manual switch of the network.

    BR,

    Peng

    thingy91_24001_24007_all_fails_together_with_tracelog.txt

    trace-2023-05-09T14-23-34.865Z_24001.bin

    trace-2023-05-09T14-27-11.143Z_24007.bin

  • 0 in reply to peng.cheng

    Hi  ,

    Sorry for the late update. It took me some days to get an external GPS antenna.

    I am using MOLEX 206640, it works much better than without it, and it can get a GNSS fix with a very high possibility.

    In the meantime, I tested Asset Tracker v2 on the nrf9160DK board, it works perfectly, and I checked the external GPS antenna is not configured.

    # CONFIG_MODEM_ANTENNA_GNSS_EXTERNAL is not set
CONFIG_MODEM_ANTENNA_AT_MAGPIO="AT%XMAGPIO=1,0,0,1,1,1574,1577"
CONFIG_MODEM_ANTENNA_AT_COEX0="AT%XCOEX0=1,1,1565,1586"

    As both boards run the same firmware and application and they both share the antenna with the LTE module, I think it could be the antenna the root cause, then I compared the two boards, the nrf9160DK has an ethertronics P822601 antenna, and Thingy:91 has an NN03-310 antenna.

    So I did some wild guesses, maybe it is the NN03-310 is not very good at receiving GPS signals, sensitivity or the SNR is not so good? I am no expert on the antenna area. But do you have some test reports for those two antennas?

    Thanks!

    BR,

    Peng

  • 0 in reply to peng.cheng

    Hi Peng, 

    Have been discussing the issue with our GNSS experts. The antenna on the nRF9160 DK is much better than the antenna on the Thingy:91, this is a know issue and is most likely due to the size. That said, the Thingy:91 should be fully usable with is NN03-310 antenna from Ignion. What version of the Thingy:91 are you using? Could  there be an issue with the board itself?

    I'm trying to find more information on the test reports.

    Kind regards,
    Øyvind

  • 0 in reply to Øyvind

    Sorry, a small correction on the DK. This has a dedicated GNSS antenna (A2), which means there are two antennas on the DK while only one combined on the Thingy:91

     

  • 0 in reply to Øyvind

    Hi  ,

    Thank you for your reply!

    If I am correct, for the nRF9160DK, I didn't set CONFIG_MODEM_ANTENNA_GNSS_EXTERNAL which means the board will not use an external GNSS antenna, it will use an onboard antenna instead, but in this case, the onboard antenna means A2 as shown in your left picture. This can explain why nRF9160DK works very well without an external GPS antenna.
    I have two Thingy:91 boards, and both two boards have the same issue with getting a GNSS fix in Place 2 as I mentioned. So it is a very low possibility that both two boars are all broken.
    The version of two Thingy:91 boards are:
    1. 1.4.0 2020.22
    2. 1.6.0 2022.49
    Thank you!
    BR,
    Peng
  • 0 in reply to peng.cheng
    peng.cheng said:
    the onboard antenna means A2 as shown in your left picture. This can explain why nRF9160DK works very well without an external GPS antenna.

    Yes, exactly. The Thingy:91 does a have an external connector J2 to connect external antenna. Please note: When an external antenna is used, the on-board Low-Noise Amplifier (LNA) should be disabled. The LNA enable signal is controlled by the COEX0 pin of the nRF9160, and its function is set by the AT%XCOEX0 AT command. The LNA makes the GPS receiver more sensitive to GPS signals and less sensitive to interference from other sources nearby.

    From the Thingy:91 HW user guide

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