Issue with nRF9160 modem connecting to Rohde & Schwarz CMW500

[Jack Panetta]

Hi,

We are currently in development of an IoT solution using the nRF9160. We are doing a set of EMC tests to ensure electromagnetic compatibility of the device. The test house we are working with uses a Rohde & Schwarz CMW500 call box to simulate and test the device connected to an LTE-M cellular network.

However, we ran into a problem where the nRF9160's modem would start the handshake with the call box but never actually resolve a network connection. The test engineer we were working with mentioned getting the modem into "roaming" mode so that it would be looking for any and all networks regardless of operator configuration. We were unable to successfully get the device into a "roaming" mode via AT commands and thus never got a connection to the call box.

We tried various versions of AT+CIND=1,1,1. This was the only command in the entire AT Command reference guide that mentioned roaming.

When reading the Network Registration Status (AT+CEREG), I see that one of the "stats" it can be is 5 – "Registered, roaming". So my question is how can I get the modem into that mode.

Any help with connecting the modem to a R&S CMW500 would be greatly appreciated.

- Jack

[Timo Vayrynen]

Hi, CMW500 should accept basically any test UICC card if the security settings are correct. For R&S CMW500 we are using R&S CMW-Z05 test UICC, which should connect to CMW500 without any additional configuration needed. So are you getting an attach reject or is the nRF9160 already failing when doing a cell search? eMTC Auto Mode with proper operating band should work "out-off-the-box". You could also check the signaling with CMWMars, but I assume that these checks have already being done by the test house and you are using proper SIM card.

[Jack Panetta]

Thanks for the detailed response.

It ended up being an issue with Call Box's configuration.

- Jack