47 C.F.R. § 90.621
(a) Applicants for frequencies in the Public Safety and Business/Industrial/Land Transportation Categories must specify on the application the frequencies on which the proposed system will operate pursuant to a recommendation by the applicable frequency coordinator. Applicants for frequencies in the SMR Category must request specific frequencies by including in their applications the frequencies requested.
(1) For trunked systems, the assignment of frequencies will be made in accordance with applicable loading criteria and in accordance with the following:
(2) For conventional systems the assignment of frequencies will be made in accordance with applicable loading criteria. Accordingly, depending upon the number of mobile units to be served, an applicant may either be required to share a channel, or, if an applicant shows a sufficient number of mobile units to warrant the assignment of one or more channels for its exclusive use, it may be licensed to use such channel or channels on an unshared basis in the area of operation specified in its application.
(b) Stations authorized on frequencies listed in this subpart, except for those stations authorized pursuant to paragraph (g) of this section and EA-based and MTA-based SMR systems, will be assigned co-channel frequencies solely on the basis of distance between fixed stations. In addition, contour overlap as detailed in paragraph (d) of this section will be the basis for geographic separation between fixed stations operating on adjacent-channel frequencies in the 809-817 MHz/854-862 MHz sub-band, except where such fixed stations meet the distance separation criteria set out in this paragraph (b).
(2) The separation between co-channel stations that have been granted exclusivity and that are located at high sites in California north of 35° N Latitude and west of 118° W Longitude shall be determined as follows:
(ii) Required co-channel separations involving antenna sites not listed in table 1 shall be determined by Commission staff on a case by case basis. The interference potential of proposed assignments will be evaluated considering parameters such as antenna height, effective radiated power, terrain irregularities, and market conditions.

(3) Except as indicated in paragraph (b)(4) of this section, stations in Channel Blocks A through V that have been granted channel exclusivity and are located in the State of Washington at the locations listed in the table below shall be separated from co-channel stations by a minimum of 169 km (105 mi). Except as indicated in paragraph (b)(4) of this section, incumbent licensees in Channel Blocks F1 through V that have received the consent of all affected parties or a certified frequency coordinator to utilize an 18 dBµV/m signal strength interference contour, have been granted channel exclusivity and are located in the State of Washington at the locations listed in the table below shall be separated from co-channel stations by a minimum of 229 km (142 mi). Locations within one mile of the geographical coordinates listed in the table below will be considered to be at that site.
| Site name | North latitude | West longitude |
|---|---|---|
| Mount Constitution | 48° 40′ 47.4″ | 122° 50′ 28.7″ |
| Lyman Mountain | 48° 35′ 41.4″ | 122° 09′ 39.6″ |
| Cultus Mountain | 48° 25′ 30.4″ | 122° 08′ 58.5″ |
| Gunsite Ridge | 48° 03′ 22.4″ | 121° 51′ 41.5″ |
| Gold Mountain | 47° 32′ 51.3″ | 122° 46′ 56.5″ |
| Buck Mountain | 47° 47′ 05.3″ | 122° 59′ 34.6″ |
| Cougar Mountain | 47° 32′ 39.4″ | 122° 06′ 34.4″ |
| Squak Mountain | 47° 30′ 14.4″ | 122° 03′ 34.4″ |
| Tiger Mountain | 47° 30′ 13.4″ | 121° 58′ 32.4″ |
| Devils Mountain | 48° 21′ 52.4″ | 122° 16′ 06.6″ |
| McDonald Mountain | 47° 20′ 11.3″ | 122° 51′ 30.5″ |
| Maynard Hill | 48° 00′ 58.3″ | 122° 55′ 35.6″ |
| North Mountain | 47° 19′ 07.3″ | 123° 20′ 48.6″ |
| Green Mountain | 47° 33′ 40.3″ | 122° 48′ 31.5″ |
| Capitol Peak | 46° 58′ 21.3″ | 123° 08′ 21.5″ |
| Rattlesnake Mountain | 47° 28′ 09.4″ | 121° 49′ 17.4″ |
| Three Sisters Mountain | 47° 07′ 19.4″ | 121° 53′ 34.4″ |
| Grass Mountain | 47° 12′ 14.1″ | 121° 47′ 42.4″ |
| Spar Pole Hill | 47° 02′ 51.4″ | 122° 08′ 39.4″ |
(4) Upon an applicant's specific request to the Commission or a frequency coordinator, co-channel stations may be separated by less than 113 km (70 mi) by meeting certain transmitter ERP and antenna height criteria. The following table indicates separations assignable to such co-channel stations for various transmitter power and antenna height combinations. The minimum separation permitted is 88 km (55 mi). Applicants will provide the Commission with a statement that the application is submitted for consideration under the table, a list of all co-channel stations within 113 km (70 mi), and the DHAATs and ERPs for these stations and the applicant's proposed station. Applicants seeking to be licensed for stations located at distances less than those prescribed in the table are required to secure a waiver and must submit with the application, in addition to the above, an interference analysis, based upon any of the generally-accepted terrain-based propagation models, that shows that co-channel stations would receive the same or greater interference protection than provided in the table. Requests for separations less than 88 km (55 mi) must also include an analysis of interference potential from mobile transmitters to existing co-channel base station receivers. Applicants seeking a waiver must submit with their application a certificate of service indicating that concurrent with the submission of the application to the Commission or a coordinator, all co-channel licensees within the applicable area were served with a copy of the application and all attachments thereto. Licensees thus served may file an opposition to the application within 30 days from the date the application is filed with the Commission.
(ii) Except for the sites listed in paragraphs (b)(1), (b)(2), and (b)(3) of this section, additional co-channel distance separation must be afforded to an existing station from an applicant wishing to locate a station less than 113 km (70 mi) from a co-channel station, where either the applicant's or the existing station is located at sites with DHAATs of 458 m (1500 ft) and above. The separation between short-spaced co-channel stations shall be determined as follows:
(C) When DHAAT values are greater than 458 m (1500 ft), use the required separation for 305 m (1000 ft) and add 1.6 km (1 mi) for every 30.5 km (100 ft), or increment thereof, of DHAAT above 458 m (1500 ft) to the distance indicated in the table. If both the proposed existing stations have DHAATs of 458 m (1500 ft) or more, the additional distance is separately determined for each station and the combined distance is added to the distance obtained from the table. Protection to existing stations will be afforded only up to 113 km (70 mi).
| Proposed station ERP (watts)/DHAAT(m) 3 | Distance between stations (km) 1 2 | ||||||
|---|---|---|---|---|---|---|---|
| Existing station DHAAT (meters) 3 | |||||||
| 305 | 215 | 150 | 108 | 75 | 54 | 37 | |
| 1000/305 | 113 | 113 | 113 | 113 | 113 | 113 | 113 |
| 1000/215 | 113 | 113 | 113 | 113 | 113 | 113 | 110 |
| 1000/150 | 113 | 113 | 113 | 113 | 112 | 108 | 103 |
| 1000/108 | 113 | 113 | 113 | 110 | 107 | 103 | 98 |
| 1000/75 | 113 | 112 | 108 | 103 | 100 | 96 | 91 |
| 1000/54 | 113 | 109 | 105 | 100 | 97 | 93 | 88 |
| 1000/37 | 109 | 104 | 100 | 95 | 92 | 88 | 88 |
| 500/305 | 113 | 113 | 113 | 113 | 113 | 113 | 110 |
| 500/215 | 113 | 113 | 113 | 112 | 109 | 105 | 100 |
| 500/150 | 113 | 112 | 108 | 103 | 100 | 96 | 91 |
| 500/108 | 112 | 107 | 103 | 98 | 95 | 91 | 88 |
| 500/75 | 107 | 102 | 98 | 93 | 90 | 88 | 88 |
| 500/54 | 103 | 98 | 94 | 89 | 88 | 88 | 88 |
| 500/37 | 99 | 94 | 90 | 88 | 88 | 88 | 88 |
| 250/305 | 113 | 113 | 113 | 112 | 109 | 105 | 100 |
| 250/215 | 113 | 113 | 107 | 102 | 99 | 95 | 90 |
| 250/150 | 109 | 104 | 100 | 95 | 92 | 88 | 88 |
| 250/108 | 105 | 100 | 96 | 91 | 88 | 88 | 88 |
| 250/75 | 99 | 94 | 90 | 88 | 88 | 88 | 88 |
| 250/54 | 95 | 90 | 88 | 88 | 88 | 88 | 88 |
| 250/37 | 91 | 88 | 88 | 88 | 88 | 88 | 88 |
| 125/305 | 113 | 111 | 107 | 102 | 99 | 95 | 90 |
| 125/215 | 108 | 103 | 99 | 94 | 91 | 88 | 88 |
| 125/150 | 103 | 98 | 94 | 89 | 88 | 88 | 88 |
| 125/108 | 98 | 93 | 89 | 88 | 88 | 88 | 88 |
| 125/75 | 93 | 88 | 88 | 88 | 88 | 88 | 88 |
| 125/54 | 88 | 88 | 88 | 88 | 88 | 88 | 88 |
| 125/37 | 88 | 88 | 88 | 88 | 88 | 88 | 88 |
| 62/305 | 108 | 103 | 99 | 94 | 91 | 88 | 88 |
| 62/215 | 103 | 98 | 94 | 89 | 88 | 88 | 88 |
| 62/150 | 97 | 92 | 88 | 88 | 88 | 88 | 88 |
| 62/108 | 92 | 88 | 88 | 88 | 88 | 88 | 88 |
| 62/75 | 88 | 88 | 88 | 88 | 88 | 88 | 88 |
| 62/54 | 88 | 88 | 88 | 88 | 88 | 88 | 88 |
| 62/37 | 88 | 88 | 88 | 88 | 88 | 88 | 88 |
| 1 Separations for stations on Santiago Peak, Sierra Peak, Mount Lukens, and Mount Wilson (CA) and the locations in the State of Washington listed in paragraph (b)(3) of this section are 56 km (35 mi) greater than those listed in the table above. In the event of conflict between this table and the table of additional California high elevation sites shown in paragraph (b)(2) of this section, the latter will apply. | |||||||
| 2 Distances shown are derived from the R-6602 curves and are based upon a non-overlap of the 22 dBu (F50,10) interference contour of the proposed station with the 40 dBu (F50,50) contour of the existing station(s). No consideration is given to the 40 dBu service contour of the proposed station and the 22 dBu contour of the existing station(s). The minimum separation of stations will be 88 km (55 mi). | |||||||
| 3 All existing stations are assumed to operate with 1000 watts ERP. When the ERP and/or DHAAT of a proposed station or the DHAAT of an existing station is not indicated in the table, the next higher value(s) must be used. |
(d) Geographic separation between fixed stations operating on adjacent channels in the 809-817/854-862 MHz Mid-Band segment must be based on lack of contour overlap as detailed in paragraphs (d)(1) through (4), unless the co-channel distance separation criteria in paragraph (b) of this section are met.
(3) Contour matrix. Interference contour levels for the contour analysis described in paragraphs (d)(1) and (2) of this section are determined using Table 4 or Table 5 to this paragraph (d)(3). Table 4 is used to determine the interference contour F(50,10) level of a fixed station operating on a 12.5 kilohertz bandwidth channel while Table 5 is used to determine the interference contour F(50,10) level of a fixed station operating on a 25 kilohertz bandwidth channel. The dBu level of the interference contour is determined by cross-referencing the modulation type of the station operating on the 25 kilohertz bandwidth channel with the modulation type of the station operating on the 12.5 kilohertz bandwidth channel.



(e) Frequencies in the 809-817/854-862 MHz bands listed as available for eligibles in the Public Safety and Business/Industrial/Land Transportation Categories are available for inter-category sharing under the following conditions:
(2) Notwithstanding paragraph (e)(5) of this section, licensees of channels in the Business/Industrial/Land Transportation category may request a modification of the license, see § 1.947 of this chapter, to authorize use of the channels for commercial operation. The licensee may also, at the same time or thereafter, seek authorization to transfer or assign the license, see § 1.948 of this chapter, to any person eligible for licensing in the General or SMR categories. Applications submitted pursuant to this paragraph must be filed in accordance with the rules governing other applications for commercial channels, and will be processed in accordance with those rules. Grant of requests submitted pursuant to this paragraph is subject to the following conditions:
(h) [Reserved]
Editorial Note:For Federal Register citations affecting § 90.621, see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at www.govinfo.gov.
Note: Coordinates are referenced to North American Datum 1983 (NAD83).
[47 FR 41032, Sept. 16, 1982]