P1 - Spurious RF emissions - 2.50x GHz

Has anyone had issues with spurious transmissions circa 2.50x GHz on a P1 based board?

The spectrum analyser was connected directly to the P1’s external antenna connector.

This is related to topic: P1 RF emissions out of band (Channel 14 Probe Request) (refer to Marker 2 on the spectrum display).

It could well be co-location issues with other circuitry, but am wondering if anyone else has had this specific issue, which so far has proven very difficult to track down…

Update for anyone that is interested.

The spurious transmissions look to be happening when there is either:

  • no WiFi
  • WiFi but no internet connection

Both of the above tests were performed in safe mode, so our application is not in the equation.

As we have lost access to our loan Spectrum Analyser, we will need to wait for delivery of our new one before we can fully answer:

  • Does the issue occur with internet connection (in safe mode)?

Good news is that we were able to resolve the spurious transmission issue within our application by calling particle.disconnect() if there is no internet connectivity.

I note that particle.disconnect() does not disconnect the WiFi radio (good).

@avtolstoy might be interested in this finding.