New rules now in effect for operating wireless microphones and similar devices will restrict their use in certain bands of the spectrum currently used for television broadcast. As a result, some equipment changes may be needed for local theaters, churches, schools, conference centers, sports stadiums and other users of such devices.
Wireless microphones and similar devices are designed to tune and operate on certain frequencies known as "spectrum bands." Most wireless microphones operate in the various unused portions of the broadcast television bands, including both VHF and UHF channels. They can be operated on either on a licensed basis, for qualifying users, or on an unlicensed basis, open to all who use the appropriate equipment, provided that users follow the applicable rules for operation on designated spectrum bands.
Changes to operations on frequencies in the 600 MHz service band
To meet increasing demand for wireless broadband services nationwide, the FCC recently auctioned spectrum that had been licensed to broadcast television stations operating on TV Channels 38-51. The results of the auction (completed in April 2017) will affect the availability of spectrum for wireless microphone operation in the 600 MHz frequencies that correspond to those channels, specifically the 614-698 MHz frequencies.
To help smooth the transition of wireless microphone operations to other available frequencies, the FCC allows users under certain conditions to continue operations on 600 MHz service band (617-652 MHz / 663-698 MHz) until July 13, 2020. However, users must not cause harmful interference either to the existing broadcast television operations or to the 600 MHz wireless service licensees' operations in the band, and users are not entitled to any interference protection from broadcast television and 600 MHz service licensees.
Available frequencies following the transition
Frequencies in the 600 MHz band that will continue to be available for wireless microphone use after the transition include:
- VHF and UHF frequencies on TV channels 2-36, which fall below 608 MHz.
- Certain frequencies in the 600 MHz guard band: 614-616 MHz.
- Certain frequencies in the 600 MHz duplex gap: 653-657 MHz for licensed use or 657-663 MHz for unlicensed use.
Unlicensed wireless microphone use is also permitted in the 902-928 MHz band, the 1920-1930 MHz, and 2.4 GHz band, under specified power levels and rules for operation for each of those bands.
Power restrictions for unlicensed mics
Unlicensed wireless mics must not be operated at a power level in excess of 50 milliwatts when operating in the TV bands, and no more than 20 milliwatts when operating in the 600 MHz guard band or duplex gap. Users are advised to consult their owner's manual or other materials provided by the manufacturer or distributor to determine the output power of their wireless microphones.
'Similar devices' to a wireless microphone
Wireless devices similar to wireless microphones include "low power auxiliary station" equipment, which typically can transmit over distances of 100 meters. Examples include wireless intercoms, wireless in-ear monitors, wireless audio instrument links and wireless cueing equipment. Operators of such unlicensed devices should follow the same rules for frequency use as wireless microphone users.
Under FCC rules, certain specified entities can obtain a license to operate in the television broadcast bands, as well as in certain other bands. In addition to the television broadcast bands, operations are permitted in portions of the 900 MHz band, the 1435-1525 MHz band and the 7 GHz band under specified rules and interference protections if users first obtain a license. Such entities include licensees of AM, FM or TV stations, broadcast networks and cable-television system operators, and venue owners/operators and professional sound companies that routinely operate 50 or more wireless microphones for events and productions at large venues such as large sports stadiums and arenas, music centers, or major theaters.
Part 74 licensees
Licensees under the Commission's Part 74 rules may operate in the spectrum bands identified in their licenses. The changes going into effect will require anyone operating in the spectrum that is now licensed for 600 MHz wireless service (most of the spectrum that was used for TV channels 38-51) to cease operation in those bands and move to lower bands authorized for use.
Restrictions in the 700 MHz band
In 2010, the Commission prohibited the use of wireless microphones and devices on unused broadcast channels in the 700 MHz band – specifically the frequencies between 698 and 806 MHz. It did so because such use could cause harmful interference that disrupts or degrades communications in the spectrum bands that had been repurposed for use by public-safety networks and licensed commercial wireless services.
Failure to comply with FCC rules by unlawfully operating wireless microphones or devices in the 600 and 700 spectrum bands may result in fines or additional criminal penalties.
Public safety licensees may contact the FCC Operations Center 24 hours a day, seven days a week, at (202) 418-1122, or FCCOperationCenter@fcc.gov to report interference. They may also contact the FCC's Public Safety Support Center at https://www.fcc.gov/general/public-safety-support-center.
Consumers may report interference with devices operating on licensed spectrum by filing a complaint with the FCC.