Sec.  90.235   Secondary fixed signaling operations.

   Fixed operations may, subject to the following conditions, be authorized on
   a secondary basis for voice, tone or impulse signaling on a licensee's
   mobile service frequency(ies) above 25 MHz within the area normally covered
   by the licensee's mobile system. Voice signaling will be permitted only in
   the Public Safety Pool.

   (a) The bandwidth shall not exceed that authorized to the licensee for the
   primary operations on the frequency concerned.

   (b) The output power shall not exceed 30 watts at the remote site.

   (c) A1D, A2D, F1D, F2D, G1D and G2D emissions may be authorized. In the
   Police Radio Service, A3E, F1E, F2E, F3E, G1E, G2E, or G3E emissions may
   also be authorized.

   (d) Except for those systems covered under paragraph (e) of this section,
   the maximum duration of any non-voice signaling transmission shall not
   exceed 2 seconds and shall not be repeated more than 3 times. Signaling
   transmissions may be staggered at any interval or may be continuous. In the
   Public Safety Pool, the maximum duration of any voice signaling transmission
   shall not exceed 6 seconds and shall not be repeated more than 3 times.

   (e) Until December 31, 1999, for systems in the Public Safety Pool
   authorized prior to June 20, 1975, and Power and Petroleum licensees as
   defined in  Sec. 90.7 authorized prior to June 1, 1976, the maximum duration of
   any signaling transmission shall not exceed 6 seconds and shall not be
   repeated more than 5 times. For Power licensees authorized between June 1,
   1976, and August 14, 1989, signaling duration shall not exceed 2 seconds and
   shall not be repeated more than 5 times. Such systems include existing
   facilities and additional facilities which may be authorized as a clear and
   direct expansion of existing facilities. After December 31, 1999, all
   signaling systems shall be required to comply with the two second message
   duration and three message repetition requirements.

   (f) Systems employing automatic interrogation shall be limited to non-voice
   techniques and shall not be activated for this purpose more than 10 seconds
   out of any 60 second period. This 10 second timeframe includes both transmit
   and response times.

   (g) Automatic means shall be provided to deactivate the transmitter in the
   event the r.f. carrier remains on for a period in excess of 3 minutes or if
   a transmission for the same signaling function is repeated consecutively
   more than five times.

   (h) Fixed stations authorized pursuant to the provisions of this section are
   exempt from the requirements of  Sec.  Sec. 90.137(b), 90.425, and 90.429.

   (i) Base, mobile, or mobile relay stations may transmit secondary signaling
   transmissions to receivers at fixed locations subject to the conditions set
   forth in this section.

   (j) Under the provisions of this section, a mobile service frequency may not
   be used exclusively for secondary signaling.

   (k) The use of secondary signaling will not be considered in whole or in
   part as a justification for authorizing additional frequencies in a
   licensee's land mobile radio system.

   (l) Secondary fixed signaling operations conducted in accordance with the
   provisions of  Sec.  Sec. 90.317(a), or 90.637(c), or 90.731 are exempt from the
   foregoing provisions of this section.

   [ 54 FR 28679 , July 7, 1989, as amended at  57 FR 34693 , Aug. 6, 1992;  58 FR 30996 , May 28, 1993;  60 FR 50123 , Sept. 28, 1995;  62 FR 18927 , Apr. 17,
   1997]