~ I'm using Wifi Analyzer on my android phone. It has a screen that shows ~ channels and their ratings, but never says how they determine the rating. ~ ~ Usually they suggest 1 or more "better" channels but I have no idea ~ whether I should switch or not. ~ ~ Right now, I'm using 9. ~ ~ Thanks.
In general, in 2.4GHz 802.11, you want to use a chunk of bandwidth that is least occupied by by anything else.
Do be aware that, in general, 802.11 carriers in 2.4GHz use about
20MHz of bandwidth (or a bit more), while a nominal "channel" is 5MHz. Or in other words, your carrier uses about 4 channels.
I.e. when you're using channel 9 (center frequency 2452 MHz), transmissions in your cell will spread from about 2440 - 2465 MHz. So you're occupying (parts of) channels 7, 8, 9, 10, 11.
Now, here's the thing. In most places, most well behaved 2.4GHz Wi-Fi uses will stick to channels 1, 6 and 11. This is because they are the 3 "non-overlapping" channels in the FCC domain. So, if you are using channel 9, you are actually interfering with (and being interfered by) cells on channels 6 and 11. So, if there are nearby APs on 6 and 11, you're actually doing WORSE than you would have had you stuck to 6 or 11.
If you want to read more, here's an article on the subject - an oldie but still valid:
So to summarize ... if you want a better channel ... use 5GHz ;-)