User guide

114 Chapter 9: Radar Detection Tool
AirMagnet Spectrum XT User Guide
Note: Most radar signals come in short bursts, followed by a dead time. Detection by
SpectrumXT would require that the bursts arrive while the SpectrumXT is on the correct channel.
The chances of this happening in the short-term may be very low. The best way to detect the radar
is to dwell on each channel for a period of time that includes several sweeps of the radar. This could
range from 10ths of seconds to several minutes.
Impact on 802.11 WLAN
Since the 802.11a/n wireless network shares the same radio frequency bands/channels with
military and weather radar systems, the FCC regulation and requirements on DFS/DFS2/
DFS3 undoubtedly puts some serious challenge to the operation of the 802.11a/n wireless
network. Care must be taken to ensure that WLAN operation will not interfere with or disrupt
the normal operation of radar systems.
Recommended Courses of Action
Based on FCC regulations, the following actions are recommended on the part of the 802.11a/
n wireless network in order to minimize or eliminate its potential inteference with military
and/or weather radar systems:
• Make sure all 802.11a/n devices that are operating on your WLAN are DFS2 or 3-cer-
tified.
• If you have uncertified 802.11a/n devices on your network, make sure that the UNII-2
and UNII-3 bands/channels are blcoked.
If you have 802.11a/n devices that are manufactured prior to July 20, 2007 (US), then check
with the vendors for possible firmware upgrade. The same goes for DFS3 requirements in
Europe.