User's Manual

20 Firetide Wireless Bridge Reference Guide Version 3.1
FCC DFS Rules
This explains how to correctly configure DFS channels so as to maintain compliance with FCC regula-
tions and guidelines. DFS operation can only be enabled and configured by a DFS-qualified professional
installer. Contact Firetide for details. All DFS-listed channels must comply with basic DFS rules, includ-
ing channel avoidance when radar signals are detected.
Channels 120, 124, and 128 have been removed from DFS service completely. These channels must not
be used in the US anywhere, at any time. They do not appear in channel listing in any Firetide product,
and are only listed here for historical reference.
Channels 116 and 132 may only be used when certain special rules have been followed. The channels
can only be used if either of the following two conditions are met:
• The transmitting antenna is more than 35 km from all TDWR stations;
OR
• The TDWR is operating on a frequency more than 30 MHz different than the equipment.
DFS Rules
Distance
You must determine if there are any trans-
mitting elements (i.e., any Firetide product)
within 35 km of any TDWR system. If there
are, you should register the installation.
RegistRation
A voluntary WISPA-sponsored database has
been developed that allows registration of
devices within 35 km of any TDWR loca-
tion (see http://www.spectrumbridge.com/
udia/home.aspx). This database is used by
government agencies to expedite resolution
of any interference with TDWRs.
channel avoiDance
When a radar signature is detected on a
channel, transmitters must stop using that
channel. The channel delection lets you con-
figure the channels to which the system can
switch, and the channels which must be avoided.
TDWR-Restricted Additional Requirements
Terminal Doppler Weather Radar systems operate in the 5600 MHz band, and must be kept free of in-
terference from all other types of equipment. For this reason, the FCC has removed channels 120, 124,
and 128 (5600-5640) from service, and placed additional restrictions on channels 116 (5580 MHz) and
132 (5660 MHz).
If you are within 35 km of a TDWR, you may not operate on any channel that is within 30 MHz of the
listed TDWR frequency. In some instances it is possible that a device may be within 35 km of multiple
TDWRs. In this case the device must ensure that it avoids operation within 30 MHz for each of the
TDWRs. This requirement applies even if the master is outside the 35 km radius but communicates with
outdoor clients which may be within the 35 km radius of the TDWRs.
The requirement for ensuring 30 MHz frequency separation is based on the best information available to
date. If interference is not eliminated, a distance limitation based on line-of-sight from TDWR will need
to be used. In addition, devices with bandwidths over 20 MHz may require greater frequency separation.
Ch. Center
Freq.
Distance
Determination
Registration Channel
Avoidance
TDWR
Restrictions
52 5260 Yes If > 35 km Yes No
56 5280 Yes If > 35 km Yes No
60 5300 Yes If > 35 km Yes No
64 5320 Yes If > 35 km Yes No
100 5500 Yes If > 35 km Yes No
104 5520 Yes If > 35 km Yes No
108 5540 Yes If > 35 km Yes No
112 5560 Yes If > 35 km Yes No
116 5580 Yes If > 35 km Yes Yes
120 5600 Banned
124 5620 Banned
128 5640 Banned
132 5660 Yes If > 35 km Yes Yes
136 5680 Yes If > 35 km Yes No
140 5700 Yes If > 35 km Yes No
Table 2.1 TDWR InsTallaTIons
This list is current as of August 2011. Elevation and antenna
height shown in feet. Refer to www.fcc.gov for the most cur-
rent version.