root@aragorn:~# iwlist wlan0 scan | grep -E 'Frequency|Quality'
Frequency:2.412 GHz (Channel 1)
Quality=34/70 Signal level=-76 dBm
Frequency:2.412 GHz (Channel 1)
Quality=52/70 Signal level=-58 dBm
Frequency:2.412 GHz (Channel 1)
Quality=28/70 Signal level=-82 dBm
Frequency:2.422 GHz (Channel 3)
Quality=30/70 Signal level=-80 dBm
Frequency:2.417 GHz (Channel 2)
Quality=34/70 Signal level=-76 dBm
Frequency:2.437 GHz (Channel 6)
Quality=42/70 Signal level=-68 dBm
Frequency:2.437 GHz (Channel 6)
Quality=33/70 Signal level=-77 dBm
Frequency:2.457 GHz (Channel 10)
Quality=40/70 Signal level=-70 dBm
Frequency:2.457 GHz (Channel 10)
Quality=36/70 Signal level=-74 dBm
Frequency:2.437 GHz (Channel 6)
Quality=28/70 Signal level=-82 dBm
Frequency:2.462 GHz (Channel 11)
Quality=28/70 Signal level=-82 dBm
Frequency:2.462 GHz (Channel 11)
Quality=31/70 Signal level=-79 dBm
Frequency:2.422 GHz (Channel 3)
Quality=25/70 Signal level=-85 dBm
Frequency:2.442 GHz (Channel 7)
Quality=26/70 Signal level=-84 dBm