Is it possible to acquire with an AT command current tx/rx frequency or EARFCN number on the bc66 modem? We need that info for the on-the-fly antenna tuning.
The second question. Once NBIoT modem (like bc66) attaches to the network, does it always stay on the same band and frequency/EARFCN? If not, is there any URC which can tell the user that band or frequency/EARFCN is changed.
AT+QENG=0 will query EARFCN, but the module cannot be in PSM when querying.
The module can switch to different EARFCN, you should query it each time the module connects to a cell (CEREG goes to 1 or 5). In my experience, when NB-IoT is deployed, the frequency stays the same as long as you are connected to the same network operator, as they usually have only one frequency pair available and put NB-IoT into guard band. But it will definitely change when using different operator.