§  74.531   Permissible service.

   (a) An aural broadcast STL station is authorized to transmit aural
   program material between the studio and transmitter location of a
   broadcasting station, except an international broadcasting station, for
   simultaneous or delayed broadcast.

   (b) An aural broadcast intercity relay station is authorized to
   transmit aural program material between broadcasting stations, except
   international broadcasting stations, for simultaneous or delayed
   broadcast.

   (c) An aural broadcast intercity relay station is authorized to
   transmit aural program material between noncommercial educational FM
   radio stations and their co-owned noncommercial educational FM
   translator stations assigned to reserved channels (Channels 201 to 220)
   and between FM radio stations and FM translator stations operating
   within the coverage contour of their primary stations. This use shall
   not interfere with or otherwise preclude use of these broadcast
   auxiliary facilities by broadcast auxiliary stations transmitting aural
   programming between broadcast stations as provided in paragraph (b) of
   this section.

   (d) An aural broadcast STL or intercity relay may be used to transmit
   material between an FM broadcast radio station and an FM booster
   station owned, operated, and controlled by the licensee of the
   originating FM radio station. This use shall not interfere with or
   otherwise preclude use of these broadcast auxiliary facilities by
   broadcast auxiliary stations transmitting aural programming between the
   studio and transmitter location of a broadcast station or between
   broadcast stations as provided in paragraphs (a) and (b) of this
   section.

   (e) An aural broadcast microwave booster station is authorized to
   retransmit the signals of an aural broadcast STL or intercity relay
   station.

   (f) Multiplexing of the STL or intercity relay transmitter may be
   employed to provide additional communication channels for the
   transmission of aural program material, news-wire teleprinter signals
   relaying news to be associated with main channel programming,
   operational communications, and material authorized to be transmitted
   over an FM station under a valid Subsidiary Communications
   Authorization (SCA). An aural broadcast STL or intercity relay station
   may not be operated solely for the transmission of operational,
   teleprinter or subsidiary communications. Operational communications
   include cues, orders, and other communications directly related to the
   operation of the broadcast station as well as special signals used for
   telemetry or the control of apparatus used in conjunction with the
   broadcasting operations.

   (g) All program material, including subsidiary communications,
   transmitted over an aural broadcast STL or intercity relay station
   shall be intended for use by broadcast stations owned or under common
   control of the licensee or licensees of the STL or intercity relay
   station. Other broadcast stations may simultaneously utilize such
   program material with permission of the STL or intercity relay station
   licensee.

   (h) In any case where multiplexing, is employed on an aural broadcast
   STL station for the simultaneous transmission of more than one aural
   channel, the STL transmitter must be capable of transmitting the
   multiple channels within the channel on which the STL station is
   authorized to operate and with adequate technical quality so that each
   broadcast station utilizing the circuit can meet the technical
   performance standards stipulated in the rules governing that class of
   broadcasting station. If multiplex operation is employed during the
   regular operation of the STL station, the additional circuits shall be
   in operation at the time that the required periodic performance
   measurements are made of the overall broadcasting system from the
   studio microphone input circuit to the broadcast transmitter output
   circuit.

   [ 28 FR 13716 , Dec. 14, 1963, as amended at  45 FR 51564 , Aug. 4, 1980;
    52 FR 31403 , Aug. 20, 1987;  55 FR 50693 , Dec. 10, 1990;  57 FR 41111 ,
   Sept. 9, 1992]