Omega Vehicle Security Wireless Sensor System zSeries - Manual (Page 68)

5.5 Fine Adjustment in Performance
1. To avoid interference from WiFi / IEEE 802.11, one could consult the figure below to
choose the best channel through the Configuration webpage. In all, channels 15, 20,
25 and 26 are not overlapping with any WiFi / IEEE 802.11 bands in the United States
while channels 15, 16, 21 and 22 can be used in Europe.
Figure 5.4 Channels
2. It is possible that IEEE 802.15.4 devices experience interference from Wi-Fi / IEEE
802.11 and Bluetooth devices and certain microwave ovens. Therefore, it is worth
locating nodes as far as possible to minimize effect. Note that international radio
regulations which govern radio equipment ensure that cell phones use their allocated
band only. It is highly unlikely that cell phones will interfere with IEEE 802.15.4
equipment.
3. In some cases, a short RF cable may be used to connect an antenna to your device.
Please note that RF extension cables will always add some loss to the transmitting
signal strength. The longer the cable the more signal will be lost over that cable.
Therefore, the length of the cable should be kept as short as possible. Also, note that
use of any other antenna other then what’s shipped with your device will void FCC
and CE regulatory compliance.
4. To achieve satisfactory IEEE 802.15.4 performance in the presence of WLAN
interference, a channel center-frequency offset of 7 MHz is recommended.
5. For co-channel operation, a physical separation from the WLAN Access Point (AP) of
26.2’ (8 m) is recommended to achieve a Packet Error Rate (PER) of 1%. For a
particularly saturated WLAN link, 29.5’ to 32.8’ (9 to 10 m) may be necessary.
6. To achieve satisfactory IEEE 802.15.4 performance in the presence of Bluetooth
interference, a separation distance of 6.5 ‘ (2 m) is recommended.
US WLAN
(IEEE 802.11B)
non-overlapping
European WLAN
(IEEE 802.11B)
non-overlapping
IEEE 802.15.4
2400 MHz PHY
Channel
1 11 6
1 13 7
Channel
Channel
2400 MHz 2483.5 MHz
2412 2437 2462
2400 MHz 2483.5 MHz
2400 MHz 2483.5 MHz
2412 2442 2472
22 MHz
2 MHz
26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11
2405 2410 2415 2420 2425 2430 2435 2440 2445 2450 2455 2460 2465 2470 2475 2480
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