Sec. 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

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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]