Base, fixed, control, and mobile transmitters in the 698-763 MHz, 775-793 MHz, and 805-806 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)
(1) The minimum D/U ratio for co-channel stations is:
(i) 40 dB at the hypothetical Grade B contour (64 dBµV/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 dBµV/m) (88.5 kilometers (55 miles)) of the DTV station; or
(iii) For transmitters operating in the 746-763 MHz, 775-793 MHz, and 805-806 MHz frequency bands, 17 dB at the equivalent Grade B contour (41 dBµV/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 dBµV/m) (88.5 kilometers (55 miles)) of the TV station or −23 dB at the equivalent Grade B contour (41 dBµV/m) (88.5 kilometers (55 miles)) of the DTV station.
(b)
(1) Licensees of stations operating within the ERP and HAAT limits of § 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 § 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 746-763 MHz, 775-787 MHz, and 788-793 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
(ii) Control, fixed, and mobile stations (including portables) that operate in the 787-788 MHz and 805-806 MHz bands and control and mobile stations (including portables) that operate in the 698-757 MHz, 758-763 MHz, 776-787 MHz, and 788-793 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 787-788 MHz and 805-806 MHz bands and control and mobile stations (including portables) that operate in the 746-757 MHz, 758-763 MHz, 776-787 MHz, and 788-793 MHz bands, 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 § 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 dBµV/m).
(C) For control, fixed, and mobile stations (including portables) that operate in the 787-788 MHz and 805-806 MHz bands and control and mobile stations (including portables) that operate in the 698-757 MHz, 758-763 MHz, 776-787 MHz, and 788-793 MHz bands, 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 (
The 88.5 km (55mi) Grade B service contour (64 dBµV/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.