Limiting WiFi Probe Request channels

[UMD]

Am working on solving this issue:

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…

At this early stage, it looks like the spurious RF transmissions that we are suffering from might be due to WiFi probe requests on the higher channels (eg channel 13).

Am wondering if it is possible to limit the WiFi channels being used by config?

Here is a related topic:

Controling WiFi Power Output

Hey all, I am looking to get my product certified and they have asked me for software which controls the WiFi output power. [54%20AM] Can that be done with the Particle P1? And has someone already written something similar?

except we want to select channels from the application firmware.

[avtolstoy]

At this early stage, it looks like the spurious RF transmissions that we are suffering from might be due to WiFi probe requests on the higher channels (eg channel 13).

Am wondering if it is possible to limit the WiFi channels being used by config ?

I'm not aware of any API provided by WICED that would let modify the channel mask, but perhaps there is some kind of an undocumented NVRAM parameter.

As a quick workaround, you may try setting the country code to US0, which will limit the channels to 1-11.

[UMD]

@avtolstoy, excellent work around!

Out of interest, it looks like the issue we were chasing was not so much of a problem. We were looking at the peaks, but EMC tests looks at averages.

Case closed.