nRF9160 NB-IoT signal strength polling

[danielClark]

Hi,

So I am trying to poll the signal strength of the nRF9160 DK and at first everything seems okay, the device gains connection and all the boxes in the LTE Link Monitor go green and can deliver RSRP values but after approximately 1 minute, it loses the ability to read the signal strength(RSRP -> 255). Then I have to reset the device again to read new signal strength values.

I am using a 1NCE sim card and am located in Germany and I have the NB-IoT firmware installed. I am using the AT+CESQ command to retrieve the signal strength information. The screenshots of the LTE link monitor output are below.

thanks in advance!

Dan

[Øyvind]

Hi Dan, 

Thanks for your patience! Our team has found the root cause, and here is their answer:
"Reason to signal loss it that the UE enters to the PSM 30 seconds after attach. PSM is activated in the used SW and the network returns T3324 value as 30 seconds and T3214_ext value as 310 hours. If Customer does not want use PSM then it is recommended to disable PSM by sending AT command AT+CPSMS=0."

Can you please try and verify this solution?

Thanks!

-Øyvind

[danielClark]

Hi Øyvind,

I can confirm that solves the problem. I didn't realise the PSM activates by default. Thank-you very much for the help.

kind regards,

Dan