Adjacent Channel definition

Would someone be willing to confirm the definition for me?
I have been reading about Adjacent Channel Support in the PMP450 series and see reference to the same term in the PTP820C Technical description document below.
Adjacent channels are literally channels next to each other on the frequency spectrum?
Consider for example channel width = 20MHz and
Ch1 = 900-920MHz
Ch2 = 920-940MHz
Ch3 = 940-960MHz
Ch4 = 960-980MHz
Ch5 = 980-1000MHz
Ch6 = 1000-1020MHz

Ch2 is adjacent to Ch1 and Ch3
Ch3 is adjacent to Ch2 and Ch4

So there are a few different things going on here…

  1. Yes, as you’ve outlined, adjacent channels are literally channels next to each other on the frequency spectrum. The main two variables that determine a channel map are the channel width and center frequency of each channel.

  2. Adjacent channel support for PMP450 is a setting that when enabled limits maximum SM TX power output to 23dBm. This feature is provided to reduce possible interference from SM’s that are close to the AP coverage edges to collocated AP’s that are using adjacent frequencies with no guard band. If there are no SM’s on the coverage edges and/or a guard band is used between adjacent AP’s, then this setting does not need to be enabled. It is disabled by default.

  3. In regards to the PTP8x0 radios, advanced frequency reuse or AFR allows for 2 or more collocated PTP8X0 radios to use the same channel, channel width and polarization as long as the antennas are spaced a minimum of 10deg? away from each other. This allows more efficient use of licensed spectrum. I’ve never actually used this feature and don’t know anyone that has. I believe it’s rare to use this in the United States.

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