In surveying local 2.4gHz activity I did a WiFi Scan with the radio (Rocket-M2) configured for channel 1. The result shows stations spread across the channels but the majority are on channel 1. Then, I set the Rocket to channel 6, re-booted and did another WiFi Scan. This time there was the same spread, but the majority of stations were now on channel 6. Switching to channel 11 produced similar results.

So, my question... Is there a bias to the way the scan is conducted (iwinfo) that favors the currently selected channel? If so, is there a way to get an unbiased scan?

Honestly I have never seen that so don't know what to say of course I don't think I have looked that close now that you mention it.

All my scans seem to be pretty well distributed, or even better distributed away from the channel I am on.

I suppose its possible though.

I can say the data is gathered in two manners

1) A scan triggers a "Request all AP's send me their name" packet (hmm I just realized this actually might be a violation when used with high gain antennas and PtMP as it could be excessive power outside ham bands) (crud now I might have to write a new warning notice for the scan page)

2) It also to my knowledge passively listens for broadcasts from AP's saying "HERE I AM" This may be the reason you see the packets as a "HERE I AM" packet is more likely to been than the node's "Who is out there" packet+response as these would be seen by the kernel code even when not scanning I think.

The WIFI scan really shouldn't be used for a site survey. It is good for seeing quickly who is around but is far from scientific.

The AirOS Spectrum View utility might be a good tool when working with viewing sites.  There is a feature in the new kernel that could use someone to write a program to take FFT data and generate similar graphs from inside BBHN build that might be nice in the future as well to give a good scan output but it needs someone to adopt it and take it under their wing to work on it.