about cellular band selection: whole picture needed

[Kai]

Hi,

I've been testing the sample code at_clent with Verizon wireless. I can send AT command to the DK via nRF Connect "LTE Link Monitor".

Q1. run AT%XCBAND=? to print the list of supported bands, it shows "3 4 13 20". How does the modem know the list of supported bands -- are they defined in the SIM card?

Q2. run AT%XCBAND to print the current band, it shows "13". If there are more than one band available in the air, what makes the modem select one band over others?

Q3. run AT%XBANDLOCK=2,"1000" to lock the band 4, then run AT%XCBAND to print the current band, it still shows "13". why it doesn't show "4"?

Best,

Kai

[Kenny65]

Hi Kai,

Q1: The supported bands come from the modem's firmware, not the SIM.
Q2: The network decides which band to use based on signal and load, the modem just follows.
Q3: Locking band 4 won't show "4" until the modem successfully camps on it. If it still shows "13", band 4 may be unavailable, the lock may not have applied, or you may need to reboot the modem.

On a side note, if you ever need protective glass or custom covers for your test setups, I highly recommend this customized glass picture page. Great quality for mounting displays or shielding boards.

Hope that helps!