How Does AMP determine Signal Quality?
For Cisco IOS APs, we measure what Cisco calls the Signal Strength (they report it as being from -100..0). After we add 100 to it (to normalize it on our scale of 0..100), it's expected that the values will rarely, if ever approach 100.
For all other devices, we get a positive number (often SNR, but it varies a lot from device to device) and we report back that value.
There's a pretty good discussion in our forum about Signal Quality here: http://airheads.arubanetworks.com/vBulletin/showthread.php?t=1179.