Goto Section: 74.705 | 74.707 | Table of Contents
FCC 74.706
Revised as of October 1, 2011
Goto Year:2010 |
2012
§ 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
§ 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 height above average terrain in the pertinent direction,
using the signal propagation method specified in § 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 § 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 § 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 (L/D ratio) fails to meet the following:
(1) -2 dB or less for co-channel operations. This maximum L/D ratio for
co-channel interference to DTV service is only valid at locations where
the signal-to-noise (S/N) ratio is 25 dB or greater. At the edge of the
noise-limited service area, where the S/N ratio is 16 dB, the maximum
L/D ratio for co-channel interference from analog low power TV, TV
translator or TV booster service into DTV service is -21 dB. At
locations where the S/N ratio is greater than 16 dB but less than 25
dB, the maximum L/D field strength ratios are found from the following
Table (for values between measured values, linear interpolation can be
used):
Signal-to-noise ratio(dB) DTV-to-low power ratio (dB)
16.00 21.00
16.35 19.94
17.35 17.69
18.35 16.44
19.35 7.19
20.35 4.69
21.35 3.69
22.35 2.94
23.35 2.44
25.00 2.00
(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, as amended at 63 FR 13563 , Mar. 20, 1998;
64 FR 4327 , Jan. 28, 1999]
Goto Section: 74.705 | 74.707
Goto Year: 2010 |
2012
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