§ 90.187Trunking in the bands between 150 and 512 MHz.
(a) Applicants for trunked systems operating on frequencies between 150 and 512 MHz (except 220-222 MHz) must indicate on their applications (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) 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 causing harmful interference to other systems. However, this monitoring requirement does not apply if the conditions in paragraph (b)(1) or (b)(2) of this section, are met:
(1) Where applicants for or licensees operating in the 470-512 MHz band meet the loading requirements of § 90.313 and have exclusive use of their frequencies in their service area.
(2) On frequencies where an applicant or licensee does not have an exclusive service area provided that all frequency coordination requirements are complied with and written consent is obtained from affected licensees using either the procedure set forth in paragraphs (b)(2)(i) and (b)(2)(ii) of this section (mileage separation) or the procedure set forth in paragraph (b)(2)(iii) of this section (protected contours).
(i) Affected licensees for the purposes of this section are licensees of stations that have assigned frequencies (base and mobile) that are 15 kHz or less removed from proposed stations that will operate with a 25 kHz channel bandwidth; stations that have assigned frequencies (base and mobile) that are 7.5 kHz or less removed from proposed stations that will operate with a 12.5 kHz bandwidth; or stations that have assigned frequencies (base and mobile) 3.75 kHz or less removed from proposed stations that will operate with a 6.25 kHz bandwidth.
(ii) Where such stations' service areas (37 dBu contour for stations in the 150-174 MHz band and 39 dBu contour for stations in the 421-512 MHz bands; see § 90.205) overlap a circle with radius 113 km (70 mi.) from the proposed base station.
(iii) In lieu of the mileage separation procedure set forth in paragraphs (b)(2)(i) and (b)(2)(ii) of this section, applicants for trunked facilities may obtain consent only from stations that would be subjected to objectionable interference from the trunked facilities. Objectionable interference will be considered to exist when the interference contour (19 dBu for VHF stations, 21 dBu for UHF stations) of a proposed trunked station would intersect the service contour (37 dBu for VHF stations, 39 dBu for UHF stations) of an existing station. The existing stations that must be considered in a contour overlap analysis are a function of the channel bandwidth of the proposed trunked station, as follows:
(A) For trunked stations proposing 25 kHz channel bandwidth: Existing co-channel stations and existing stations that have an operating frequency 15 kHz or less from the proposed trunked station.
(B) For trunked stations proposing 12.5 kHz channel bandwidth: Existing co-channel stations and existing stations that have an operating frequency 7.5 kHz or less from the proposed trunked station.
(C) For trunked stations proposing 6.25 kHz channel bandwidth: Existing co-channel stations and existing stations that have an operating frequency 3.75 kHz or less from the proposed trunked station.
(iv) The calculation of service and interference contours referenced in paragraph (b)(2)(iii) of this section shall be done using generally accepted engineering practices and standards which, for purposes of this section, shall presumptively be the practices and standards agreed to by a consensus of all certified frequency coordinators.
(v) The written consent from the licensees specified in paragraphs (b)(2)(i) and (b)(2)(ii) or (b)(2)(iii)(A), (b)(2)(iii)(B) and (b)(2)(iii)C of this section shall specifically 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 trunked station and be made available to the Commission upon request. The submission of a coordinated trunked application to the Commission shall include a certification from the applicant that written consent has been obtained from all licensees specified in paragraphs (b)(2)(i) and (b)(2)(ii) or (b)(2)(iii)(A), (b)(2)(iii)(B) and (b)(2)(iii)(C) of this section that the written consent documents encompass the complete understandings and agreements of the parties as to such consent; and that the terms and conditions thereof are consistent with the Commission's rules. Should a potential applicant disagree with a certified frequency coordinator's determination that objectionable interference exists with respect to a given channel or channels, that potential applicant may request the Commission to overturn the certified frequency coordinator's determination. In that event, the burden of proving by clear and convincing evidence that the certified frequency coordinator's determination is incorrect shall rest with the potential applicant. If a licensee has consented to the use of trunking, but later decides against the use of trunking, that licensee may request that the licensee(s) of the trunked system(s) cease the use of trunking. Should the trunked station(s) decline the licensee's request, the licensee may request a replacement channel from the Commission. A new applicant whose interference contour overlaps the service contour of a trunked licensee will be assigned the same channel as the trunked licensee only if the trunked licensee consents in writing and a copy of the written consent is submitted to the certified frequency coordinator responsible for coordination of the application.
(c) Trunking of systems licensed on paging-only channels or licensed in the Radiolocation Service (subpart F) is not permitted.
(d) Potential applicants proposing trunked operation may file written notice with any certified frequency coordinator for the pool (Public Safety or Industrial/Business) in which the applicant proposes to operate. The notice shall specify the channels on which the potential trunked applicant proposes to operate and the proposed effective radiated power, antenna pattern, height above ground, height above average terrain and proposed channel bandwidth. On receipt of such a notice, the certified frequency coordinator shall notify all other certified frequency coordinators in the relevant pool within one business day. For a period of sixty days thereafter, no application will be accepted for coordination which specifies parameters that would result in objectionable interference to the channels specified in the notice. Potential applicants shall not file another notice for the same channels within 10 km (6.2 miles) of the same location unless six months shall have elapsed since the filing of the last such notice. Certified frequency coordinators shall return without action, any coordination request which violates the terms of this paragraph (d).
(e) No more than 10 channels for trunked operation in the Industrial/Business Pool may be applied for in a single application. Subsequent applications, limited to an additional 10 channels or fewer, 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 trunked operation 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. Applicants in the Public Safety Pool may request more than 10 channels at a single location provided that any application for more than 10 Public Safety Pool channels must be 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 grant of the application.
(f) If a licensee authorized for trunked operation discontinues trunked operation for a period of 30 consecutive days, the licensee, within 7 days of the expiration of said 30 day period, shall file a conforming application for modification of license with the Commission. Upon grant of that application, new applicants may file for the same channel or channels notwithstanding the interference contour of the new applicant's proposed channel or channels overlaps the service contour of the station that was previously engaged in trunked operation.