I need to make sure that the receiver is active in an NRF52832 that I don't have good ability to do DTM commands on; there's a host processor that can do some DTM commands, but visibility of control is poor. The receiver needs to be running for receive-only emissions regulatory testing. Ordinarily I would sniff the RF emissions of the NRF52 receive local oscillator to be sure that the host processor commands are sending the NRF52832 the right commands and the receiver is running. I don't have the local oscillator equation for the NRF52, but I have the NRF51 local oscillator equation as (8/7)* (2400 + channel_number + 2), so for example for RF receiver operation at 2.402GHz I'd expect to see LO leakage at 2745.142MHz, if the NRF51 and NRF52 have the same receiver architecture, where we use the Bluetooth channel numbering and call that channel 0. But I see nothing down to at least -110dBm in 5kHz resolution bandwidth, looking over a 50MHz span centered at 2.745GHz, sniffing with a dipole antenna laid over the NRF52. The obvious possibility is that the DTM receive-only mode is not occurring due to my control software having an error, but I need to check the alternatives. Is the local oscillator frequency different for the NRF52 vs. the NRF51? If so, what is the correct local oscillator frequency equation for the NRF52? And, about what level of RF local oscillator emissions in receive mode should I expect?
