FCC Test Behavior

[NickRA]

Hello!

Our design involves the combination of several radios (Wifi, Cellular LTE-M (Nordic nRF9160), and SubGHz) on a single device, each of which may transmit at the same time. Our test house has informed us that we need to spot check each cellular band in which we intend to operate. As best I understand it, the nRF9160 may operate in any of the nine LTE-M bands, selecting the most optimal band for the environments it encounters in the field. As such, our test application allows the test house to select a band and run their scans at will.

I am less certain of how to select a modulation scheme. LTE-M can operate in 16-QAM or QPSK. How does the nRF9160 select between these two modulation schemes in the field? Do we need to assume that the device may select either one at will or at the request of a cell tower, or is there some kind of static configuration that binds the behavior to one or the other?

This will inform the behavior of our test application.

Thanks!

[Simonr]

Hi

The best will likely be to use AT radio test commands so you're able to inflict the "worst case" scenarios at full TX power and at the frequencies you want to test. Modulation shouldn't have very much to say, but to answer the question, the LTE-M can use multiple modulation forms, and the base station will be the deciding factor here.

Best regards,

Simon