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Cooper Bussmann 245U-E Wireless Ethernet Modem & Device Server User Manual
Rev Version 2.19
Figure 21 2.4-GHz Channels
The following table shows the US power and operational constraints.
Group 1
5.15–5.25 GHz
@ 50 mW
Group 2
5.25–5.35 GHz
@ 250 mW to 1 Watt
Group 3
5.47–5.725 GHz
@ 250 mW to 1 Watt
Group 4
5.725–5.825 GHz
@ 1 Watt
Each frequency band has certain limitations on the amount of radiated power that it can output, as well as whether
the band uses Dynamic Frequency Selection (DFS), which is explained in the next section.
Figure 22 5-GHz Channels
Dynamic Frequency Selection
Because of the push within the 802.11a market to open up new spectrum for unlicensed radio, a mechanism called
Dynamic Frequency Selection (DFS) was developed so that the 802.11 Wi-Fi could coexist with existing military
and telecommunication radar systems. Access points with 5-GHz radios comply with regulations that require radio
devices to use DFS, which can detect radar signals and avoid interfering with them by automatically scanning and
then selecting another channel or band.