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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

Parents
  • 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

    Sorry, I got too focused on the eDRX issue. 

    It is important to know that the GPS receiver operation is time multiplexed with LTE modem, and it is possible to use the GPS and QZSS receiver to obtain position either while the LTE is in RRC Idle mode or power saving mode (PSM), or when the LTE modem is completely deactivated. Also note, GPS signals do not usually penetrate ceilings or other structures. For best GPS performance, Nordic Thingy:91 should be used outside in an open space, far from sources of interference and other structures that may block the signals.

    Where are you performing the tests of the GPS? 


  • 0 in reply to Øyvind

    No worries!

    I tested in mainly two places,

    one is  in a residential area that is a bit far away from the city center,

    the other is on the top floor of an 8-floor building near the city center,

    both two places are outside places and have no visual blocks to the sky.

  • 0 in reply to peng.cheng

    Hello again, our R&D team have looked at the modem traces and your case. 

    Their initial response is that the GNSS reception is not good. Could you give a more precise description of where you are testing? Are there any walls around you, or metal, etc. The GNSS receiver alone is quite sensitive, and the antenna on the Thingy:91 is shared between the LTE and GNSS, which can cause lower performance.

    If possible, could you test with an external GNSS antenna connected to J2, as shown in the hardware description of the Thingy:91.

    Before doing that, one thing to check is the LNA configuration, %XMAGPIO, which should be something like this:

    AT%XMAGPIO=1,1,1,7,1,746,803,2,698,748,2,1710,2200,3,824,894,4,880,960,5,791,849,7,1565,1586
    Note that this should automatically be configured when building a project for thingy91_nrf9160_ns
  • 0 in reply to Øyvind

    Hi,

    Thanks for your response!

    I attached two pictures, they are the Google 3d map of the two places.

    Place 1 is in a residential area that is a bit far away from the city center,

    Place 2 is on the top floor of an 8-floor building near the city center.

    LNA configuration is exactly the same as yours.

    AT%XMAGPIO?
%XMAGPIO: 1,1,1,7,1,746,803,2,698,748,2,1710,2200,3,824,894,4,880,960,5,791,849,7,1565,1586
OK

    I don't have an external GPS antenna at my side, let me see if I can find one.

    BR,

    Peng

  • 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

Reply
  • 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

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