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                                                                    DA 12-459

                                                           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
   U-NII devices.

   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 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 or

   To request materials in accessible formats for people with disabilities
   (Braille, large print, electronic files, audio format), send an e-mail to 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,, (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
   (OET Guidance).

   See 47 C.F.R. S: 15.5.

   See OET Guidance, supra note 6.

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                                  Page 1 of 3

                            FCC ENFORCEMENT ADVISORY

   Federal Communications Commission

   445 12th St., S.W.

   Washington, D.C. 20554

                                        News Media Information 202 / 418-0500


                                                          TTY: 1-888-835-5322