Sec. 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, medical services systems in the 150-
160 MHz band are permitted to be cross-banded for mobile and central 
stations operations with mobile relay stations authorized to operate in 
the 450-470 MHz band.
    (2) [Reserved]
    (3) In the Industrial/Business Pool, on frequencies designated with 
an ``LR'' in the coordinator column of the frequency table in 
Sec. 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 Sec. 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 Sec. 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 
Sec. 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]

    Effective Date Note: At  62 FR 18928 , Apr. 17, 1997, Sec. 90.243 was 
amended by revising paragraphs (a), (b)(1), (b)(3), (c)(3), (c)(4), and 
(c)(5) and removing and reserving paragraph (b)(2), effective Oct. 17, 
1997.