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BAS-SVX40K-EN
Figure 74. Channel Quality Scan screen showing channels 17 and 18 with heavy traffic that will
not support Air-Fi communication
Points to remember:
• The bars do not indicate signal strength.
• The taller green bars indicate quieter channels which have more available bandwidth and are more
likely to get BACnet messages through.
• Channels above 30% will have enough available bandwidth to support sending and receiving
BACnet messages over the Zigbee channel.
• Buildings typically use Wi-Fi channels 1, 6 and 11 for their wireless networks. See Figure 75, p. 109
below which shows how Wi-Fi and Zigbee channels relate to each other in the 2.4 GHz spectrum.
– Wi-Fi channel 1 broadcasts in the space where Zigbee channels 11 through 14 are located.
– Wi-Fi channel 6 broadcasts in the space where Zigbee channels 16 through 19 are located.
– Wi-Fi channel 11 broadcasts in the space where Zigbee channels 21 through 24 are located.
• Wi-Fi channels are about 20 MHz wide, but they seldom use all of that bandwidth. See Figure 75, p.
109. Zigbee channels that are situated near the edges of the Wi-Fi channels are able to
communicate without problem because Wi-Fi is not always using the entire channel. For instance,
Zigbee channel 11 and 14 are at the edge of Wi-Fi channel 1, but are able to communicate without
trouble as long as Wi-Fi channel 1 is not using the entire channel.
• Other Zigbee channels like 12 and 13 are near the center of Wi-Fi channel 1, but if Wi-Fi channel 1
is not being used, or does not have a lot of traffic, Zigbee channels 12 and 13 will work fine.
• Wi-Fi and Zigbee channels are designed to coexist with each other under typical conditions.
However, sometimes Wi-Fi channels have extraordinary traffic on them and can use up much of the
available bandwidth.
• Note channels 15, 20 and 25 are not affected by Wi-Fi channels 1, 6 and 11. Channel 26 is not used
by Air-Fi.
• In the Figure 74, p. 108 above, Wi-Fi channel 6 (which uses the space where Zigbee channels 16
through 19 are located) has heavy traffic and is taking up most of the bandwidth to a point where
Zigbee channels 17 and 18 are red and don’t have enough bandwidth to support good Air-Fi
communication.
Using the Tracer® TU Service Tool with a Wireless Network
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