§  90.243   Mobile relay stations.

   (a) Mobile relay operations will be authorized on frequencies below 512
   MHz, except in the Radiolocation Service.

   (b) Special provisions for mobile relay operations:

   (1) In the Public Safety Pool, systems operating on any of the public
   safety frequencies listed in § 90.20(c) are permitted to be cross-banded
   for mobile stations operations with mobile relay stations where such
   stations are authorized.

   (2) [Reserved]

   (3) In the Industrial/Business Pool, on frequencies designated with an
   “LR” in the coordinator column of the frequency table in § 90.35(b)(3),
   mobile relay operation shall be on a secondary basis to other
   co-channel operations.

   (4) Except where specifically precluded, a mobile relay station may be
   authorized to operate on any frequency available for assignment to base
   stations.

   (5) A mobile station associated with mobile relay station(s) may not be
   authorized to operate on a frequency below 25 MHz.

   (c) Technical requirements for mobile relay stations.

   (1) Each new mobile relay station with an output power of more than one
   watt, and authorized after January 1, 1972, that is activated by
   signals below 50 MHz shall deactivate the station upon cessation of
   reception of the activating continuous coded tone signal. Licensees may
   utilize a combination of digital selection and continuous coded tone
   control where required to insure selection of only the desired mobile
   relay station.

   (2) Mobile relay stations controlled by signals above 50 MHz or
   authorized prior to January 1, 1972, to operate below 50 MHz are not
   required to incorporate coded signal or tone control devices unless the
   transmitters are consistently activated by undesired signals and cause
   harmful interference to other licensees. If activation by undesired
   signals causes harmful interference, the Commission will require the
   installation of tone control equipment within 90 days of a notice to
   the licensee.

   (3) Except in the Industrial/Business Pool, on frequencies designated
   with an “LR” in the coordinator column of the frequency table in
   § 90.35(b)(3), each new mobile-relay station authorized after January 1,
   1972, shall be equipped for automatic deactivation of the transmitter
   within 5 seconds after the signals controlling the station cease.

   (4) Except in the Industrial/Business Pool, on frequencies designated
   with an “LR” in the coordinator column of the frequency table in
   § 90.35(b)(3), each new mobile-relay station authorized after January 1,
   1972, during periods that is not controlled from a manned fixed control
   point; shall have an automatic time delay or clock device that will
   deactivate the station not more than 3 minutes after its activation by
   a mobile unit.

   (5) In the Industrial/Business Pool, on frequencies designated with an
   “LR” in the coordinator column of the frequency table in § 90.35(b)(3),
   each mobile relay station, regardless of the frequency or frequencies
   of the signal by which it is activated shall be so designated and
   installed that it will be deactivated automatically when its associated
   receiver or receivers are not receiving a signal on the frequency or
   frequencies which normally activate it.

   (6) Multiple mobile relay station radio systems shall use wireline or
   radio stations on fixed frequencies for any necessary interconnect
   circuits between the mobile relay stations.

   [ 43 FR 54791 , Nov. 22, 1978, as amended at  49 FR 40177 , Oct. 15, 1984;
    50 FR 13606 , Apr. 5, 1985;  50 FR 39680 , Sept. 30, 1985;  50 FR 40976 ,
   Oct. 8, 1985;  54 FR 39740 , Sept. 28, 1989;  56 FR 19603 , Apr. 29, 1991;
    56 FR 32517 , July 17, 1991;  60 FR 37268 , July 19, 1995;  61 FR 6576 ,
   Feb. 21, 1996;  62 FR 18928 , Apr. 17, 1997;  74 FR 23803 , May 21, 2009]