Sec. 74.706  Digital TV (DTV) station protection.

    (a) For purposes of this section, the DTV station protected service 
area is the geographic-area in which the field strength of the station's 
signal exceeds the noise-limited service levels specified in 
Sec. 73.622(e) of this chapter. The extremity of this area (noise-
limited perimeter) is calculated from the authorized maximum radiated 
power (without depression angle correction), the horizontal radiation 
pattern, and

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height above average terrain in the pertinent direction, using the 
signal propagation method specified in Sec. 73.625(b) of this chapter.
    (b)(1) An application to construct a new low power TV or TV 
translator station or change the facilities of an existing station will 
not be accepted if it specifies a site which is located within the 
noise-limited service perimeter of a co-channel DTV station.
    (2) Due to the frequency spacing which exists between TV channels 4 
and 5, between Channels 6 and 7, and between Channels 13 and 14, 
adjacent channel protection standards shall not be applicable to these 
pairs of channels.
    (c) The low power TV, TV translator or TV booster station field 
strength is calculated from the proposed effective radiated power (ERP) 
and the antenna height above average terrain (HAAT) in pertinent 
directions.
    (1) For co-channel protection, the field strength is calculated 
using Figure 9a, 10a, or 10c of Sec. 73.699 (F(50,10) charts) of part 73 
of this chapter.
    (2) For adjacent channel protection, the field strength is 
calculated using Figure 9, 10, or 10b of Sec. 73.699 (F(50,50) charts) 
of part 73 of this chapter.
    (d) A low power TV, TV translator or TV booster station application 
will not be accepted if the ratio in dB of its field strength to that of 
the DTV station fails to meet the following:
    (1)-21 dB for co-channel operations at the noise-limited perimeter 
of the DTV station.
    (2) +48 dB for adjacent channel operations at:
    (i) The DTV noise-limited perimeter if a low power TV, TV translator 
or TV booster station is located outside that perimeter.
    (ii) At all points within the DTV noise-limited area if a low power 
TV or TV translator is located within the DTV noise-limited perimeter, 
as demonstrated by the applicant.

[ 62 FR 26721 , May 14, 1997]