FEDERAL COMMUNICATIONS COMMISSION 
WASHINGTON 
OFFICE OF 
THE CHAIRMAN 
The Honorable G.K. Butterfield 
U.S. House of Representatives 
2305 Rayburn House Office Building 
Washington, D.C. 20515 
Dear Congressman Butterfield: 
August 20, 2015 
Thank you for your letter urging the Commission to preserve the 600 MHz duplex gap 
for use by wireless microphones in all markets. The Commission adopted new rules on August 
5, 2015, to address the long-term needs of wireless microphone users by providing for continued 
access to the 600 MHz band and expanding access to other bands. The new rules specifically 
will allow all Part 74 licensed microphone users to operate in a 4-megahertz portion of the 600 
MHz duplex gap (i.e., broadcasters, cable programming networks, movie studios, and operators 
at major sporting/concerts/theater venues). The Commission may need to place a broadcaster in 
the duplex gap in a limited number of markets. However, the Commission sought comment on 
preserving an additional vacant television channel for use by wireless microphones and white 
space devices should this occur. 
The rules also provide new opportunities for licensed microphone users. In the TV 
bands, they will be allowed greater use of the VHF channels and co-channel operation inside 
digital TV contours without coordination if TV signals fall below specified thresholds. The new 
rules also will allow licensed microphone users to operate on a secondary basis in three 
additional spectrum bands, consistent with the Commission's spectrum management goals: (1) 
access to significantly more spectrum in the 900 MHz band; (2) access to a portion of the 1435-
1525 MHz band at specified times and places, subject to coordination requirements that protect 
critical aeronautical mobile telemetry; and (3) access to portions of the 6875-7125 MHz band. 
Together with the rules also adopted by the Commission regarding unlicensed wireless 
microphone use of the 600 MHz band, these new rules provide for efficient sharing of the TV 
and 600 MHz bands to accommodate various wireless microphone users, while continuing to 
protect the licensed users of each of the bands. I appreciate your interest in this matter. Please 
let me know if I can be of any further assistance. 
Sincerel~4~ l-
~eeler 
FEDERAL COMMUNICATIONS COMMISSION 
WASHINGTON 
OFFICE OF 
THE CHAIRMAN 
The Honorable Tony Cardenas 
U.S . House of Representatives 
1508 Longworth House Office Building 
Washington, D.C. 20515 
Dear Congressman Cardenas: 
August 20, 2015 
Thank you for your letter urging the Commission to preserve the 600 MHz duplex gap 
for use by wireless microphones in all markets. The Commission adopted new rules on August 
5, 2015 , to address the long-term needs of wireless microphone users by providing for continued 
access to the 600 MHz band and expanding access to other bands. The new rules specifically 
will allow all Part 74 licensed microphone users to operate in a 4-megahertz portion of the 600 
MHz duplex gap (i.e., broadcasters, cable programming networks, movie studios, and operators 
at major sporting/concerts/theater venues). The Commission may need to place a broadcaster in 
the duplex gap in a limited number of markets. However, the Commission sought comment on 
preserving an additional vacant television channel for use by wireless microphones and white 
space devices should this occur. 
The rules also provide new opportunities for licensed microphone users. In the TV 
bands, they will be allowed greater use of the VHF channels and co-channel operation inside 
digital TV contours without coordination if TV signals fall below specified thresholds. The new 
rules also will allow licensed microphone users to operate on a secondary basis in three 
additional spectrum bands, consistent with the Commission's spectrum management goals: (1) 
access to significantly more spectrum in the 900 MHz band; (2) access to a portion of the 1435-
1525 MHz band at specified times and places, subject to coordination requirements that protect 
critical aeronautical mobile telemetry; and (3) access to portions of the 6875-7125 MHz band. 
Together with the rules also adopted by the Commission regarding unlicensed wireless 
microphone use of the 600 MHz band, these new rules provide for efficient sharing of the TV 
and 600 MHz bands to accommodate various wireless microphone users, while continuing to 
protect the licensed users of each of the bands. I appreciate your interest in this matter. Please 
let me know if I can be of any further assistance. 
Sincerelyh~l 
~eeler 
FEDERAL COMMUNICATIONS COMMISSION 
WASHINGTON 
OFFICE OF 
THE CHAIRMAN 
The Honorable Bobby L. Rush 
U.S. House of Representatives 
2268 Rayburn House Office Building 
Washington, D.C. 20515 
Dear Congressman Rush: 
August 20, 2015 
Thank you for your letter urging the Commission to preserve the 600 MHz duplex gap 
for use by wireless microphones in all markets. The Commission adopted new rules on August 
5, 2015, to address the long-term needs of wireless microphone users by providing for continued 
access to the 600 MHz band and expanding access to other bands. The new rules specifically 
will allow all Part 74 licensed microphone users to operate in a 4-megahertz portion of the 600 
MHz duplex gap (i.e., broadcasters, cable programming networks, movie studios, and operators 
at major sporting/concerts/theater venues). The Commission may need to place a broadcaster in 
the duplex gap in a limited number of markets. However, the Commission sought comment on 
preserving an additional vacant television channel for use by wireless microphones and white 
space devices should this occur. 
The rules also provide new opportunities for licensed microphone users . In the TV 
bands, they will be allowed greater use of the VHF channels and co-channel operation inside 
digital TV contours without coordination if TV signals fall below specified thresholds. The new 
rules also will allow licensed microphone users to operate on a secondary basis in three 
additional spectrum bands, consistent with the Commission's spectrum management goals: ( 1) 
access to significantly more spectrum in the 900 MHz band; (2) access to a portion of the 1435-
1525 MHz band at specified times and places, subject to coordination requirements that protect 
critical aeronautical mobile telemetry; and (3) access to portions of the 6875-7125 MHz band . 
Together with the rules also adopted by the Commission regarding unlicensed wireless 
microphone use of the 600 MHz band, these new rules provide for efficient sharing of the TV 
and 600 MHz bands to accommodate various wireless microphone users, while continuing to 
protect the licensed users of each of the bands. I appreciate your interest in this matter. Please 
let me know if I can be of any further assistance. 
-7ihti 
Tom Wheeler