Sec.  27.60   TV/DTV interference protection criteria.

   Base, fixed, control, and mobile transmitters in the 698–764 MHz and 776–794
   MHz frequency bands must be operated only in accordance with the rules in
   this section to reduce the potential for interference to public reception of
   the signals of existing TV and DTV broadcast stations transmitting on TV
   Channels 51 through 68.

   (a) D/U ratios. Licensees must choose site locations that are a sufficient
   distance from co-channel and adjacent channel TV and DTV stations, and/or
   must use reduced transmitting power or transmitting antenna height such that
   the following minimum desired signal-to-undesired signal ratios (D/U ratios)
   are met.

   (1) The minimum D/U ratio for co-channel stations is:

   (i) 40 dB at the hypothetical Grade B contour (64 dB µV/m) (88.5 kilometers
   (55 miles)) of the TV station;

   (ii) For transmitters operating in the 698–746 MHz frequency band, 23 dB at
   the equivalent Grade B contour (41 dB µV/m) (88.5 kilometers (55 miles)) of
   the DTV station; or

   (iii) For transmitters operating in the 746–764 MHz and 776–794 MHz
   frequency bands, 17 dB at the equivalent Grade B contour (41 dB µV/m) (88.5
   kilometers (55 miles)) of the DTV station.

   (2) The minimum D/U ratio for adjacent channel stations is 0 dB at the
   hypothetical Grade B contour (64 dB µV/m) (88.5 kilometers (55 miles)) of the
   TV station or −23 dB at the equivalent Grade B contour (41 dB µV/m) (88.5
   kilometers (55 miles)) of the DTV station.

   (b) TV stations and calculation of contours. The methods used to calculate
   TV contours and antenna heights above average terrain are given in  Sec.  Sec. 73.683
   and 73.684 of this chapter. Tables to determine the necessary minimum
   distance from the 698–764 MHz or 776–794 MHz station to the TV/DTV station,
   assuming that the TV/DTV station has a hypothetical or equivalent Grade B
   contour of 88.5 kilometers (55 miles), are located in  Sec. 90.309 of this
   chapter and labeled as Tables B, D, and E. Values between those given in the
   tables may be determined by linear interpolation. Distances for station
   parameters greater than those indicated in the tables should be calculated
   in accordance with the required D/U ratios, as provided in paragraph (a) of
   this section. The locations of existing and proposed TV/DTV stations during
   the period of transition from analog to digital TV service are given in part
   73 of this chapter and in the final proceedings of MM Docket No. 87–268.

   (1) Licensees of stations operating within the ERP and HAAT limits of  Sec. 27.50
   must select one of four methods to meet the TV/DTV protection requirements,
   subject to Commission approval:

   (i) Utilize the geographic separation specified in Tables B, D, and E of
    Sec. 90.309 of this chapter, as appropriate;

   (ii) When station parameters are greater than those indicated in the tables,
   calculate geographic separation in accordance with the required D/U ratios,
   as provided in paragraph (a) of this section;

   (iii) Submit an engineering study justifying the proposed separations based
   on the parameters of the land mobile station and the parameters, including
   authorized and/or applied for facilities, of the TV/DTV station(s) it is
   trying to protect; or,

   (iv) Obtain written concurrence from the applicable TV/DTV station(s). If
   this method is chosen, a copy of the agreement must be submitted with the
   application.

   (2) The following is the method for geographic separations.

   (i) Base and fixed stations that operate in the 746–764 MHz and 777–792 MHz
   bands having an antenna height (HAAT) less than 152 m. (500 ft.) shall
   afford protection to co-channel and adjacent channel TV/DTV stations in
   accordance with the values specified in Table B (co-channel frequencies
   based on 40 dB protection) and Table E (adjacent channel frequencies based
   on 0 dB protection) in  Sec. 90.309 of this chapter. Base and fixed stations that
   operate in the 698–746 MHz band having an antenna height (HAAT) less than
   152 m. (500 ft.) shall afford protection to adjacent channel DTV stations in
   accordance with the values specified in Table E in  Sec. 90.309 of this chapter,
   shall afford protection to co-channel DTV stations by providing 23 dB
   protection to such stations' equivalent Grade B contour (41 dB µV/m), and
   shall afford protection to co-channel and adjacent channel TV stations in
   accordance with the values specified in Table B (co-channel frequencies
   based on 40 dB protection) and Table E (adjacent channel frequencies based
   on 0 dB protection) in  Sec. 90.309 of this chapter. For base and fixed stations
   having an antenna height (HAAT) between 152–914 meters (500–3,000 ft.) the
   effective radiated power must be reduced below 1 kilowatt in accordance with
   the values shown in the power reduction graph in Figure B in  Sec. 90.309 of this
   chapter. For heights of more than 152 m. (500 ft.) above average terrain,
   the distance to the radio path horizon will be calculated assuming smooth
   earth. If the distance so determined equals or exceeds the distance to the
   hypothetical or equivalent Grade B contour of a co-channel TV/DTV station
   (i.e., it exceeds the distance from the appropriate Table in  Sec. 90.309 of this
   chapter to the relevant TV/DTV station), an authorization will not be
   granted unless it can be shown in an engineering study (see paragraph
   (b)(1)(iii) of this section) that actual terrain considerations are such as
   to provide the desired protection at the actual Grade B contour (64 dB µV/m
   for TV and 41 dB µV/m for DTV stations) or unless the effective radiated
   power will be further reduced so that, assuming free space attenuation, the
   desired protection at the actual Grade B contour (64 dB µV/m for TV and 41
   dB µV/m coverage contour for DTV stations) will be achieved. Directions for
   calculating powers, heights, and reduction curves are listed in  Sec. 90.309 of
   this chapter for land mobile stations. Directions for calculating coverage
   contours are listed in  Sec.  Sec. 73.683 through 73.685 of this chapter for TV
   stations and in  Sec. 73.625 of this chapter for DTV stations.

   (ii) Control, fixed, and mobile stations (including portables) that operate
   in the 776–777 MHz and 792–794 MHz bands and control and mobile stations
   (including portables) that operate in the 698–746 MHz, 747–762 MHz and
   777–792 MHz bands are limited in height and power and therefore shall afford
   protection to co-channel and adjacent channel TV/DTV stations in the
   following manner:

   (A) For control, fixed, and mobile stations (including portables) that
   operate in the 776–777 MHz and 792–794 MHz bands and control and mobile
   stations (including portables) that operate in the 747–762 MHz and 777–792
   MHz band, co-channel protection shall be afforded in accordance with the
   values specified in Table D (co-channel frequencies based on 40 dB
   protection for TV stations and 17 dB for DTV stations) in  Sec. 90.309 of this
   chapter.

   (B) For control and mobile stations (including portables) that operate in
   the 698–746 MHz band, co-channel protection shall be afforded to TV stations
   in accordance with the values specified in Table D (co-channel frequencies
   based on 40 dB protection) and to DTV stations by providing 23 dB protection
   to such stations' equivalent Grade B contour (41 dB µV/m).

   (C) For control, fixed, and mobile stations (including portables) that
   operate in the 776–777 MHz and 792–794 MHz bands and control and mobile
   stations (including portables) that operate in the 698–746 MHz, 747–762 MHz,
   and 777–792 MHz band, adjacent channel protection shall be afforded by
   providing a minimum distance of 8 kilometers (5 miles) from all adjacent
   channel TV/DTV station hypothetical or equivalent Grade B contours (adjacent
   channel frequencies based on 0 dB protection for TV stations and −23 dB for
   DTV stations).

   (D) Since control, fixed, and mobile stations may affect different TV/DTV
   stations than the associated base or fixed station, particular care must be
   taken by applicants/licensees to ensure that all appropriate TV/DTV stations
   are considered (e.g., a base station may be operating within TV Channel 62
   and the mobiles within TV Channel 67, in which case TV Channels 61, 62, 63,
   66, 67 and 68 must be protected). Control, fixed, and mobile stations shall
   keep a minimum distance of 96.5 kilometers (60 miles) from all adjacent
   channel TV/DTV stations. Since mobiles and portables are able to move and
   communicate with each other, licensees must determine the areas where the
   mobiles can and cannot roam in order to protect the TV/DTV stations.

   Note to  Sec. 27.60: The 88.5 km (55 mi) Grade B service contour (64 dB µV/m) is
   based on a hypothetical TV station operating at an effective radiated power
   of one megawatt, a transmitting antenna height above average terrain of 610
   meters (2000 feet) and the Commission's R–6602 F(50,50) curves. See  Sec. 73.699
   of this chapter. Maximum facilities for TV stations operating in the UHF
   band are 5 megawatts effective radiated power at an antenna HAAT of 610
   meters (2,000 feet). See  Sec. 73.614 of this chapter. The equivalent contour for
   DTV stations is based on a 41 dB µV/m signal strength and the distance to the
   F (50,90) curve. See  Sec. 73.625 of this chapter.

   [ 65 FR 3148 , Jan. 20, 2000, as amended at  65 FR 17605 , Apr. 4, 2000;  65 FR 42883 , July 12, 2000;  67 FR 5511 , Feb. 6, 2002;  69 FR 59535 , Oct. 4, 2004]