No LTE Connectivity

[Servo]

Hello All,

I recently started testing  an nRF9160 DK board. I was able to follow through all the instructions, registered on nRF cloud and successfully connected to LTE. But ever since, for some reason the board just refuses to connect to the network. I have tried resetting the board, I even added the board again on nRF cloud but to no avail.

Has anyone encountered something similar? Please help me solve this issue. (Note: I have only used 0.52 MB of the provided data)

Thanks in advance.

[Servo]

Hello Heidi,

Apologies for the late reply. I got sidelined with other tasks at hand. Please find here the latest log from today. Hope this will help clear up the issue. 

Sincerely,

Sarvjit

Fullscreen 2020-06-17T17_46_23.864Z-log.txt Download

2020-06-17T17:46:28.413Z INFO Application data folder: C:\Users\sarvj\AppData\Roaming\nrfconnect\pc-nrfconnect-linkmonitor
2020-06-17T17:46:28.981Z DEBUG App pc-nrfconnect-linkmonitor v1.1.1 official
2020-06-17T17:46:28.982Z DEBUG App path: C:\Users\sarvj\.nrfconnect-apps\node_modules\pc-nrfconnect-linkmonitor
2020-06-17T17:46:28.982Z DEBUG nRFConnect 3.3.3 is supported by the app (^3.2.0)
2020-06-17T17:46:28.982Z DEBUG nRFConnect path: C:\Users\sarvj\AppData\Local\Programs\nrfconnect\resources\app.asar
2020-06-17T17:46:28.982Z DEBUG HomeDir: C:\Users\sarvj
2020-06-17T17:46:28.982Z DEBUG TmpDir: C:\Users\sarvj\AppData\Local\Temp
2020-06-17T17:46:32.306Z INFO Modem port is opened
2020-06-17T17:46:35.920Z DEBUG modem >> AT\x0D\x0A
2020-06-17T17:46:36.919Z ERROR Error: 'AT
' timed out
2020-06-17T17:46:45.963Z DEBUG modem >> at+creg?\x0D\x0A
2020-06-17T17:46:46.964Z ERROR Error: 'at+creg?
' timed out
2020-06-17T17:47:00.042Z DEBUG modem >> AT+COPS=?\x0D\x0A
2020-06-17T17:47:10.193Z INFO Modem port is opened
2020-06-17T17:47:12.525Z DEBUG modem >> AT+CFUN?\x0D\x0A
2020-06-17T17:47:13.526Z ERROR Error: 'AT+CFUN?
' timed out
2020-06-17T17:47:46.819Z DEBUG modem >> AT\x0D\x0A
2020-06-17T17:47:47.820Z ERROR Error: 'AT
' timed out
2020-06-17T17:48:00.044Z ERROR Network search failed: Error: 'AT+COPS=?
' timed out
2020-06-17T17:48:00.045Z DEBUG modem >> AT+COPS=?\x0D\x0A
2020-06-17T17:49:00.046Z ERROR Network search failed: Error: 'AT+COPS=?
' timed out
2020-06-17T17:49:22.191Z DEBUG modem >> at+creg?\x0D\x0A
2020-06-17T17:49:23.193Z ERROR Error: 'at+creg?
' timed out

[Servo]

Hello Heidi,

I was able to flash the asset tracker and it is now connected to the network. But for some reason the connection is very unstable and keeps disconnecting every few seconds. I have attached the log here.

We are mulling on using the Nordic nRF9160 lte board as the default for communication in our portable device. As such, I am trying to conduct a test on the signal quality, specifically [rssi, ber] values for different scenarios. Could you also help with the same if possible. I have successfully conducted similar tests on other lte devices using putty. It is imperative that I conduct a similar test on nRF9160 to compare results.

Please advise.

Thank You

Sincerely,

Sarvjit2020-06-22T19_44_16.154Z-log.txt

[Heidi]

Hi! 

From the logs it looks like you're not having an issue with the LTE connection, but rather the connection to nRF Cloud. This is most likely because there is something wrong with the nRF Connect for Cloud certificates on the modem. To re-provision the certificates, you can follow this tutorial. Mare sure to do everything in the correct order. However, you don't really need the connection to nRF Cloud to test the signal quality.

You can use either the AT Client sample or the Serial LTE Modem application to do this. Use AT commands to connect to the LTE network.

You can use +CESQ to read out [rsrq, rsrp], but it doesn't look like we have support for reading out RSSI or BER. I've put in a request with the modem FW team to see if they have any suggestions are a possible work-around for this.

Best regards,

Heidi

[Heidi]

UPDATE: Bit Error Ratio isn't supported in LTE, which is why we don't have support for it. RSSI can be calculated from the RSRQ and RSRP values like this:

RSSI = 10log(N) + RSRP - RSRQ. 

N is Resource Blocks and is 6 for LTE M1.