One question about nRF9160 LTE RX test.

[RongLinQin]

Hello nordic support:

   We want to measure nRF9160's LTE RX SNR  at production stage. 

   According to the document nwp_034--nRF9160 Hardware.pdf ==> 4.6.1. Following command "AT%XRFTEST" is for read RX SNR. 

   We used CMW as signal generator。And have one question, what kind wave is needed for this test.  Is it continuous wave or LTE Cat-M modulated wave? 

Thanks!

BRs

Qin, Rong-Lin

[Hakon]

Their response;

https://infocenter.nordicsemi.com/pdf/nrf91_at_commands_v2.0.pdf
--> Chapter 11.5 RX SNR test %XRFTEST

"The set command measures SNR.
To measure SNR correctly, the CW offset must be +330 kHz for the LTE-M mode and +45 kHz for the NB-IoT
mode."

--> This means not modulated sinusoidal RF signal offset from Channel Center Frequency set by %XRFTEST <param1> described in chapter 11.5

--> To set maximum gain for receiver recommended CW signal level is around -90dBm at nRF9160 LTE input pin, hence expected SNR result is in range 16...18dB.

--> For Rx SNR measurement it is recommended to use AFC calibration (Chapter 11.6) prior SNR test to get correct SNR result.