The Federal Communications Commission (FCC) has announced that is working to resolve interference to Terminal Doppler Weather Radar (TDWR) systems used at airports that has occurred from some outdoor wireless systems operating in the 5.4 GHz(5470 MHz-5725 MHz) band. These wireless devices are required to implement radar detection and DFS functions when operating as a master device and are subject to Section 15.407 of FCC rules. As per the FCC, they are working with the FAA and NTIA to develop long term equipment authorization test procedures that will ensure that the devices comply with FCC rules and also protect the TDWR operations. In the interim, the FCC will allow certification of wireless master devices with radar detection function and with DFS capability, if they meet the following conditions:

• Devices are intended for indoor operations only;
• Devices will not permit operations on channels which overlap the 5600-5650 MHz band;
• Devices meet all the other requirements specified in Section 15.407 and no configuration controls are  provided to change the frequency of operations outside the grant of certification for US operation.

All the devices operating in the 5.4 GHz band and subject to the DFS requirements must be submitted to the Commission's Laboratory Division for pre-grant testing and equipment authorization. The grantee must ensure that the applications subject to this interim procedure must include appropriate attestations that the device is intended for indoor use (through a clear indication in a manual or labels with the device) and must demonstrate through test reports that the transmission is disabled in the 5600-5650 MHz band.

The FCC is continuing to evaluate what additional measures may need to be taken to further ensure against interference from 5 GHz outdoor wireless systems located near airports.  The FCC also states that while manufacturers have an obligation to ensure that their equipment complies with FCC rules and must take steps to ensure their devices do not cause harmful interference, Section 15.5 of the Commission's rules also places an obligation on users of devices that operate under Part 15 to avoid causing interference and correct any interference that may occur and that it is incumbent on users to cooperate with manufacturers to implement any changes necessary to facilitate compliance.