there are a number of devices ,mostly on channel 1 and 2, a few on channel 3,6,9,11..we intend to use those channels least in use, and if in use already, least signal strength. For this output one needs to type on the terminal (linux not used windows for this test):
$ sudo iw dev wlan0 scan | grep signal
for signal strength, and
$ sudo iw dev wlan0 scan | grep channel
to display the channels in use. If you run these commands while standing at the same position you are sure to get a matching number of output items(i guess respectively arranged-no sure way of telling this).