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September 27, 2012
Enforcement Advisory No. 2012-07
TDWR and U-NII DEVICES
Enforcement Bureau Takes Action to Prevent Interference to
FAA-Operated Terminal Doppler Weather Radars Critical to Flight Safety
The Enforcement Bureau recently took action against several companies for
operating devices that caused interference to Terminal Doppler Weather
Radars (TDWRs) maintained by the Federal Aviation Administration (FAA).
TDWR systems operating in the 5600-5650 MHz band are used by the FAA to
obtain quantitative measurements for gust fronts, wind shear, microbursts,
and similar information.
Investigations conducted by the FCC, the FAA, and the National
Telecommunications and Information Administration (NTIA) in several areas
of the United States and Puerto Rico revealed that much of the
interference stems from wireless devices sharing the same band as TDWR
systems, and operating outdoors in the vicinity of airports at high
elevations that are line-of-sight to the TDWR installations and most are
operating inconsistent with the FCC Part 15 Rules. The Enforcement Bureau
and the FAA continue to investigate additional areas where interference is
reported to TDWR systems, and will continue to take appropriate
enforcement action as necessary.
What do the rules require?
Manufacturers, marketers, and users of U-NII devices are hereby cautioned
that only devices certified under FCC Part 15, Subpart E of the Rules may
be operated as U-NII devices. For those U-NII devices operating as a
master device in the 5.25 GHz - 5.35 GHz and 5.47 GHz - 5.725 GHz bands, a
Dynamic Frequency Selection (DFS) radar detection mechanism must be
enabled. A piece of equipment is no longer certified as required under the
FCC rules if it is installed or configured to defeat DFS, to utilize
antennas other than those certified for the device, or to make other
changes that modify the equipment beyond the configuration that has been
certified. Using uncertified U-NII devices, or certified U-NII devices in
an unauthorized manner, violates the FCC Part 15 Rules and may result in
interference to radio communications services critical to public safety.
Users are also cautioned that operation of the U-NII device must not cause
harmful interference, and if harmful interference occurs, the operation
must cease immediately. Furthermore, federal law prohibits willful or
malicious interference to authorized radio communications.
What Should U-NII Operators Do to Comply?
Users of U-NII devices must ensure certified devices are installed and
configured properly. Additionally, if the U-NII devices are installed and
operating within 35 km of a TDWR system, users are required to take
special precautions on the frequency of operation as described in the OET
Guidance 443999. We caution users of U-NII devices, however, that a U-NII
device must not cause interference to a TDWR system, regardless of the
distance between the U-NII device and the TDWR.
In fact, operators of U-NII devices under FCC Part 15 Rules must not only
refrain from causing interference but also must accept interference from
licensed devices such as the TDWR systems. Any user causing interference
may be required to cease operating the U-NII device, even if the device in
use was properly certified and configured, and will not be permitted to
resume operation until the condition causing the interference has been
corrected. Even if they avoid or fix any interference problems, however,
U-NII operators may only operate those devices within authorized
frequencies, power limitations, and other technical requirements.
Finally, the FCC encourages users of U-NII devices near the TDWR systems
to register in the voluntary database system discussed in the Guidance.
What Should Manufacturers and Retailers Do to Comply?
As noted above, manufacturers must ensure that U-NII devices capable of
operating in certain bands have a DFS radar detection mechanism and must
not have software configurations that allow users to disable the features.
We also require manufacturers of U-NII devices to remind their customers
to ensure that the U-NII devices are properly configured and used in an
authorized manner and that they do not cause interference to TDWRs as
described in the various guidance documents. Moreover, retailers must
ensure that the equipment they are marketing complies with FCC rules. We
will continue to work with manufacturers and retailers to adopt tools to
better educate their customers and other parties about the rules governing
What Are the Penalties that Apply?
Violations of the FCC Part 15 Rules may subject the responsible party to
enforcement action, including substantial monetary forfeitures, seizure of
the equipment, and criminal sanctions, including imprisonment. Therefore,
this advisory emphasizes the importance of complying strictly with these
important legal requirements.
Need more information?
To file a complaint regarding noncompliant U-NII devices, visit
http://esupport.fcc.gov/complaints.htm. For additional information
regarding compliance with and enforcement of the rules governing U-NII
devices and TDWR systems interference, please contact the Enforcement
Bureau at (202) 418-7450. For general information on U-NII devices and
TDWR systems, please visit
To request materials in accessible formats for people with disabilities
(Braille, large print, electronic files, audio format), send an e-mail to
firstname.lastname@example.org or call the Consumer & Governmental Affairs Bureau at
202-418-0530 (voice), (202) 418-0432 (TTY). You may also contact the
Enforcement Bureau on its TTY line at (202) 418-1148 for further
information about this Enforcement Advisory, or the FCC on its TTY line at
1-888-Tell-FCC (1-888-835-5322) for further information about the rules
governing U-NII devices.
Media inquiries should be directed to William Davenport,
William.Davenport@fcc.gov, (202) 418-1034.
Issued by: Chief, Enforcement Bureau
VPNet, Inc., Notice of Apparent Liability for Forfeiture and Order, 27 FCC
Rcd 2879 (Enf. Bur. 2012); Argos Net, Inc., Notice of Apparent Liability
for Forfeiture and Order, 27 FCC Rcd 2786 (Enf. Bur. 2012); Insight
Consulting Group of Kansas City, LLC, Notice of Apparent Liability of
Forfeiture and Order, 26 FCC Rcd 10699 (Enf. Bur. 2011); Ayustar Corp.,
Notice of Apparent Liability for Forfeiture and Order, 26 FCC Rcd 10693
(Enf. Bur. 2011); Rapidwave, LLC, Notice of Apparent Liability for
Forfeiture and Order, 26 FCC Rcd 10678 (Enf. Bur. 2011); AT&T, Inc.,
Notice of Apparent Liability for Forfeiture, 26 FCC Rcd 1894 (Enf. Bur.
2011); Utah Broadband, Notice of Apparent Liability for Forfeiture, 26 FCC
Rcd 1419 (Enf. Bur. 2011) (forfeiture paid). See also Ayustar Corp.,
Memorandum Opinion and Order, 25 FCC Rcd 16,249 (Enf. Bur. 2010); Sling
Broadband, LLC, Forfeiture Order, 26 FCC Rcd 13062 (Enf. Bur. 2011).
47 C.F.R. S:S: 15.1 et seq.
See 47 C.F.R. S:S: 15.401 - 15.407. See also Memorandum from Julius Knapp,
Chief, Office of Engineering and Technology, FCC, and P. Michele Ellison,
Chief, Enforcement Bureau, FCC, to Manufacturers and Operators of
Unlicensed 5 GHz Outdoor Network Equipment Re: Elimination of Interference
to Terminal Doppler Weather Radar (TDWR) (dated July 27, 2010), available
See 47 C.F.R. S: 15.5. Harmful interference is defined as "[a]ny emission,
radiation or induction that endangers the functioning of a radio
navigation service or of other safety services or seriously degrades,
obstructs or repeatedly interrupts a radio communications service." 47
C.F.R. S: 15.3(m).
See 47 U.S.C. S: 333.
See OET KDB Publication 443999 available at
See 47 C.F.R. S: 15.5.
See OET Guidance, supra note 6.
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FCC ENFORCEMENT ADVISORY
Federal Communications Commission
445 12th St., S.W.
Washington, D.C. 20554
News Media Information 202 / 418-0500