§ 90.187   Trunking in the bands between 150 and 512 MHz.

   (a) Applicants for centralized and decentralized trunked systems
   operating on frequencies between 150 and 512 MHz (except 220-222 MHz)
   must indicate on their applications (radio service and class of station
   code, instructions for FCC Form 601) that their system will be trunked.
   Licensees of stations that are not trunked may trunk their systems only
   after modifying their license (see § 1.927 of this chapter).

   (b) Except as provided in paragraphs (c) and (d) of this section,
   trunked systems operating under this section must employ equipment that
   prevents transmission on a trunked frequency if a signal from another
   system is present on that frequency. The level of monitoring must be
   sufficient to avoid harmful interference to other systems.

   (c) The monitoring requirement in paragraph (b) of this section does
   not apply to trunked systems operating in the 470-512 MHz band that
   meet the loading requirements of § 90.313 and have exclusive use of
   their frequencies in their service area.

   (d) The monitoring requirement in paragraph (b) of this section does
   not apply if the application is accompanied by written consent from all
   affected licensees.

   (1) Affected licensees for the purposes of this section are licensees
   (and previously filed pending applicants) meeting both a spectral and a
   contour overlap as defined:

   (i) Spectral overlap. Licensees (and filers of previously filed pending
   applications) with an assigned (or proposed) frequency having a
   spectral separation from a frequency of the proposed centralized
   trunked station that does not exceed these values:
   Proposed station  Incumbent authorized bandwidth
                     25 kHz  12.5 kHz    6.25 kHz
   25 kHz           15.0 kHz 15.0 kHz 15.0 kHz
   12.5 kHz         15.0 kHz 7.5 kHz  7.5 kHz
   6.25 kHz         15.0 kHz 7.5 kHz  5.0 kHz

   The left column is the authorized bandwidth requested for the proposed
   trunked station. The second row is the authorized bandwidth of the
   incumbent. The other cells in the table show the frequency range above
   and below the frequency of the proposed centralized trunked station
   that must be considered.

   (ii) Contour overlap. (A) Licensees (and filers of previously filed
   pending applications) with a service contour (37 dBu for stations in
   the 150-174 MHz band, and 39 dBu for stations in the 421-512 MHz band)
   that is overlapped by the proposed centralized trunked station's
   interference contour (19 dBu for stations in the 150-174 MHz band, and
   21 dBu for stations in the 421-512 MHz band). Contour calculations are
   required for base station facilities. Contour calculations are required
   for associated mobile stations only in the 150-174 MHz band, with the
   associated base station's service contour used as both the mobile
   station's service contour and its interference contour.

   (B) The calculation of service and interference contours shall be
   performed using generally accepted engineering practices and standards,
   including appropriate derating factors, agreed to by a consensus of all
   certified frequency coordinators. Frequency coordinators shall make
   this information available to the Commission upon request.

   (C) For purposes of this section, the authorized operating area of a
   station or proposed station with no associated base station shall be
   used as both the station's service contour and its interference
   contour.

   (D) After January 1, 2013, licensees with an authorized bandwidth
   exceeding 12.5 kHz will not be deemed affected licensees, unless the
   licensee meets the efficiency standard set forth in § 90.203(j)(3) or
   the licensee was granted a waiver of § 90.209(b).

   (2) The written consent from an affected licensee shall state all terms
   agreed to by the parties and shall be signed by the parties. The
   written consent shall be maintained by the operator of the centralized
   trunked station and be made available to the Commission upon request.
   An application for a centralized trunked station shall include either a
   certification from the applicant that written consent has been obtained
   from all affected licensees, or a certification from the frequency
   coordinator that there are no affected licensees.

   (3) In addition, the service contour for proposed centralized trunked
   stations on Industrial/Business Pool frequencies shall not be
   overlapped by an incumbent licensee's interference contour. An
   application filed for Public Safety Pool frequencies, see § 90.20, for a
   proposed centralized trunked station in which the service contour of
   the proposed station is overlapped by the interference contour of the
   incumbent station(s) is allowed, but the applicant must accept any
   resultant interference.

   (e) The exclusive service area of a station that has been authorized
   for centralized trunked operation will be protected from proposed
   centralized trunked, decentralized trunked or conventional operations
   in accordance with the standards of paragraph (d) of this section.

   (f) Trunking of systems licensed on paging-only channels or licensed in
   the Radiolocation Service (subpart F) is not permitted.

   (g) Channel limits. (1) No more than 10 channels for new centralized
   trunked operation in the Industrial/Business Pool may be applied for at
   a single transmitter location or at locations with overlapping service
   contours as specified in paragraph (d) of this section. Subsequent
   applications for centralized trunked operation are limited to no more
   than an additional 10 channels, and must be accompanied by a
   certification, submitted to the certified frequency coordinator
   coordinating the application, that all of the applicant's existing
   channels authorized for centralized trunked operation at that location
   or at locations with overlapping service contours have been constructed
   and placed in operation. Certified frequency coordinators are
   authorized to require documentation in support of the applicant's
   certification that existing channels have been constructed and placed
   in operation.

   (2) Applicants for Public Safety Pool channels may request more than 10
   centralized trunked channels at a single location or at locations with
   overlapping service contours if accompanied by a showing of sufficient
   need. The requirement for such a showing may be satisfied by submission
   of loading studies demonstrating that requested channels in excess of
   10 will be loaded with 50 mobiles per channel within a five year period
   commencing with the grant of the application.

   (h) If a licensee authorized for centralized trunked operation
   discontinues trunked operation for a period of 30 consecutive days, the
   licensee, within 7 days thereafter, shall file a conforming application
   for modification of license with the Commission.

   [ 78 FR 28754 , May 16, 2013, as amended at  80 FR 18146 , Apr. 3, 2015]

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Subpart I—General Technical Standards

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