Sec. 21.909  MDS response stations.

    (a) An MDS response station is authorized to provide communication 
by voice and/or data signals with its associated MDS station. An MDS 
response

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station may be operated only by the licensee of the MDS station or its 
subscriber and only at receiving location of the MDS station with which 
it is communicating. More than one response station may be operated at 
the same or different receiving locations. All MDS response stations 
communicating with a single MDS station shall operate within the same 
frequency channel. The specified frequency channel which may be used by 
the response station is determined by the channel assigned to the MDS 
station with which it communicates. The specified frequency channel may 
be subdivided to provide a distinct operating frequency for each of more 
than one response station.
    (b) Authorization of an MDS response station is subject to the 
following terms and conditions:
    (1) The response station shall not cause interference to any station 
operating beyond the service area of the MDS station with which it 
communicates.
    (2) The antenna structure height employed at any location shall not 
exceed the criteria set forth in Sec. 17.7 of this chapter.
    (c) The response channels associated with channels E3, E4, F3, F4, 
H1, H2, and H3 are allocated to the private operational-fixed service 
(part 94 of this chapter).
[ 48 FR 33901 , July 26, 1983, as amended at  52 FR 27556 , July 22, 1987; 
 52 FR 37786 , Oct. 9, 1987;  56 FR 57818 , Nov. 14, 1991]