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245U-E Wireless Ethernet Modem User Manual
23
Rev Version 2.24
On the 20-MHz channel (green), most of the energy is transmitted within the channel but some of the
energy is transmitted on the channels on either side, therefore causing interference on the these channels.
The 10-MHz channels (orange) are similar, with half of the energy overlapping into the next channel, but
you can configure up to 6 x non-interfering channels at the same time. The 5-MHz channels (blue) do not
overlap, so all 13 channels can be used at the same time. There is also a single 40-MHz Channel (purple)
that takes up over half of the full 2.4-GHz band, and is therefore much more susceptible to interference
from other channels.
If there is more than one 802.11 access point within the same wireless range, it is important that the access
points are on channels that are as far apart as possible. If there are two 20-MHz channel access points, set
them to channel 1 and 11. If there are three, set them to 1, 6, and 11.
802.11a (5 GHz)
The 245U-E-A utilizes frequency bands within the range of 5.15 GHz and 5.825 GHz. This is broken into 4
distinct U-NII bands, and each region (for example, EU, US, AUS, NZ) has their own power and operational
constraints. See “Appendix C - CHANNELS” for details.
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.
