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  • Case ID: 354291
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nRF9151-DK – NCELLMEAS Command Returning Only a Single Cell

fabricio.almeida

Hello,

I'm currently using the nRF9151-DK hardware to develop our product based on the nRF9151 SiP. We selected the ncs-serial-modem firmware, and the modem is controlled via AT commands by our main MCU.

We are evaluating the nRF Cloud Location feature to determine device position using cellular or Wi-Fi data. I have implemented and tested this functionality in multiple areas around Uberlândia, Brazil.

However, I’ve observed that Single Cell Location does not provide the accuracy we need, so I tried using the Multi-Cell Location service. According to the documentation (https://docs.nordicsemi.com/bundle/addon-serial_modem-latest/page/app/NRFCLOUD_AT_commands.html), the NCELLMEAS command should perform a neighboring cell scan.

During my field tests at over 15 different locations across the city, every NCELLMEAS scan returned only one cell after a few hundred milliseconds — as shown in the AT command output below. On the nRF Cloud Location web interface, my results always appear as Single Cell, never Multi-Cell.

[SER] 2023-01-01T00:00:15 TX Modem 14 bytes: AT%NCELLMEAS
[SER] 2023-01-01T00:00:15 RX Modem 6 bytes: OK
[SER] 2023-01-01T00:00:15 RX Modem 71 bytes: %NCELLMEAS: 0,"05314208","72405","9CC6",48,9610,411,71,26,7060,6733
[SER] 2023-01-01T00:00:15 TX Modem 21 bytes: AT#XNRFCLOUDPOS=2,0
[SER] 2023-01-01T00:00:15 RX Modem 6 bytes: OK
[SER] 2023-01-01T00:00:16 RX Modem 46 bytes: #XNRFCLOUDPOS: 0,-18.905003,-48.241289,546


In the coverage area of my residence, I have already observed the nRF9151 connecting to three different Cells, so I believe there is neighboring cell coverage available.

I also rebuilt and flashed the ncs-serial-modem firmware with trace logging enabled to analyze the behavior. The same issue persisted — only a single cell is reported in each scan. I’ve attached the trace log file for reference.

Could you please clarify if there are:

  1. Any specific commands or configuration parameters required to enable multi-cell scanning?

  2. Any known hardware limitations on the nRF9151 that prevent multi-cell measurements?

Thank you for your support.

trace-2025-11-18T12-54-25.346Z.mtrace

Parents Reply Children
  • 0 in reply to fabricio.almeida
    fabricio.almeida said:
    However, I always get the same result: only one cell is reported, and the command returns immediately.

    I guess, the modem is not sleeping.

    To execute a neighbor cell scan, the "receiver" must be free to use. If your modem is active, that command can't use it. Therefore I wrote "requires the modem in power sleeping to start".

    %XMODEMSLEEP: 1,86386638
I 35.102 : app> modem state: sleeping on
scan 5 6
I 44.218 : sh app active
I 44.218 : >AT%NCELLMEAS=5,6
I 44.260 : LTE modem wakes up
%XMODEMSLEEP: 1,0
I 44.260 : app> modem state: sleeping off
OK
I 44.261 : sh app inactive
I 12.801 : CAT-M1 neighbor cell measurements 0/4
I 12.802 :   # :  plmn    tac      cell  band earfnc pid rsrp/q dB(m)
I 12.802 : [ 0]: 26203  0xe936 0x01656201  20  6200  251   -91/ -8
I 12.802 : [ 1]: 26201  0x67b9 0x01CC2B03  20  6400  206   -91/ -9
I 12.802 : [ 2]: 26201  0x67b9 0x01CC2B06   3  1444  270  -107/ -7
I 12.803 : [*3]: 26201  0x67b9 0x01CC2B00   3  1300  151  -104/-12
I 12.803 : (*3 : current cell)
I 12.803 : Scans 2, improves 1, 69 s, overall 69 s
I 12.900 : LTE modem sleeps (PSM)
%XMODEMSLEEP: 1,86308844
I 12.900 : app> modem state: sleeping on

  • 0 in reply to Achim Kraus

    What do you mean by “active”?
    I’ll attach the full AT command sequence that I’m currently using. But in summary: I first connect to a cell, then open the nRF Cloud socket, and only after that I trigger the cell scan command

    [SER] 2023-01-01T00:00:05 TX Modem 11 bytes: AT#XRESET  
[SER] 2023-01-01T00:00:05 RX Modem 6 bytes:   OK 
[SER] 2023-01-01T00:00:06 RX Modem 7 bytes: Ready
[SER] 2023-01-01T00:00:06 TX Modem 13 bytes: AT+CEMODE=0  
[SER] 2023-01-01T00:00:06 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:06 TX Modem 12 bytes: AT+CEREG=5  
[SER] 2023-01-01T00:00:06 RX Modem 6 bytes:   OK 

[SER] 2023-01-01T00:00:26 TX Modem 24 bytes: AT%XSYSTEMMODE=1,1,0,1  
[SER] 2023-01-01T00:00:26 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:26 TX Modem 47 bytes: AT%XBANDLOCK=2,"1000000000000000000000010101"  
[SER] 2023-01-01T00:00:26 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:26 TX Modem 69 bytes: AT%XCOUNTRYDATA=1,"4,724,1,0,3,0,5,0,28,0","5,724,1,0,3,0,5,0,28,0"  
[SER] 2023-01-01T00:00:26 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:26 TX Modem 20 bytes: AT+CGDCONT=1,IP,em  
[SER] 2023-01-01T00:00:26 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:26 TX Modem 11 bytes: AT%XSIM=1  
[SER] 2023-01-01T00:00:26 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:26 TX Modem 11 bytes: AT%CESQ=1  
[SER] 2023-01-01T00:00:26 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:26 TX Modem 13 bytes: AT%XSNRSQ=1  
[SER] 2023-01-01T00:00:26 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:26 TX Modem 11 bytes: AT+CFUN=1  
[SER] 2023-01-01T00:00:27 RX Modem 6 bytes:   OK 
[SER] 2023-01-01T00:00:28 RX Modem 33 bytes:   +CEREG: 2,"9CC6","05314208",7  
[SER] 2023-01-01T00:00:30 RX Modem 57 bytes:   +CEREG: 1,"9CC6","05314208",7,,,"11100000","11100000"  
[SER] 2023-01-01T00:00:31 TX Modem 12 bytes: AT+CGPADDR  
[SER] 2023-01-01T00:00:31 RX Modem 28 bytes:   +CGPADDR: 0,"100.80.0.7"  
[SER] 2023-01-01T00:00:31 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:31 TX Modem 13 bytes: AT%XMONITOR  
[SER] 2023-01-01T00:00:31 RX Modem 104 bytes:   %XMONITOR: 1,"","","72405","9CC6",7,28,"05314208",411,9610,67,36,"","11100000","11100000","01001001"  
[SER] 2023-01-01T00:00:31 TX Modem 16 bytes: AT#XNRFCLOUD=1  
[SER] 2023-01-01T00:00:32 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:35 RX Modem 19 bytes:   #XNRFCLOUD: 1,0  
[SER] 2023-01-01T00:00:41 TX Modem 14 bytes: AT%NCELLMEAS  
[SER] 2023-01-01T00:00:41 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:41 RX Modem 73 bytes:   %NCELLMEAS: 0,"05314208","72405","9CC6",43,9610,411,66,23,34659,33385  
[SER] 2023-01-01T00:00:41 TX Modem 21 bytes: AT#XNRFCLOUDPOS=2,0  
[SER] 2023-01-01T00:00:41 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:00:42 RX Modem 46 bytes:   #XNRFCLOUDPOS: 0,-18.905003,-48.241289,546
[SER] 2023-01-01T00:00:44 TX Modem 16 bytes: AT#XNRFCLOUD=0  
[SER] 2023-01-01T00:00:44 RX Modem 19 bytes:   #XNRFCLOUD: 0,0  
[SER] 2023-01-01T00:00:44 RX Modem 6 bytes:   OK  
[SER] 2023-01-01T00:01:14 TX Modem 11 bytes: AT+CFUN=0  
[SER] 2023-01-01T00:01:14 RX Modem 6 bytes:   OK
     

  • 0 in reply to fabricio.almeida

    You will need to configure your device for PSM (see +CPSMS).

    fabricio.almeida said:
    What do you mean by “active”?

    That's when the modem is not sleeping.

    In your case it is "active" between cfun=1 and cfun=0. therefore NCELLMEAS only reports the value for the current selected cell.

  • 0 in reply to Achim Kraus

    In Brazil, PSM is not commonly supported by the operators. I’ve already tried enabling PSM, but the network rejected the request.

    Given that, is there any way to perform %NCELLMEAS without relying on PSM?
    I've also tried to perform NCELLMEAS before active CFUN=1, but it return: ERROR.

  • 0 in reply to fabricio.almeida

    "No PSM" is outside of my experience. I'm just an other user and I don't know, how to execute %NCELLMEAS with that.

    I guess you need to wait for an Nordic engineer.

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