Dell SonicPoint-N Dual Radio Getting Started Manual page 32

Channel Utilization
The channel utilization graph shows how channels are being
utilized for each SonicPoint.
The number on the top of each color bar indicates the average
signal strength magnitude each SonicPoint detects for the
indicated channel. High magnitudes (greater than 240) are
shown in red and generally indicate that the corresponding
channel is overloaded.
Note: Although some channels are not used in all countries,
they are still shown, as it is possible for a wireless
cracker to launch denial of service attacks to adjacent
channels.
Channel Utilization | 31