§ 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]

   return arrow Back to Top

Subpart I—General Technical Standards

   return arrow Back to Top