§  73.616   Post-transition DTV station interference protection.

   (a) Applications seeking facilities that will operate prior to the end
   of the DTV transition must also comply with §  73.623.

   (b) A petition to add a new channel to the post-transition DTV Table of
   Allotments contained in §  73.622(i) of this subpart will not be
   accepted unless it meets: the DTV-to-DTV geographic spacing
   requirements of §  73.623(d) with respect to all existing DTV allotments
   in the post-transition DTV Table; the principle community coverage
   requirements of §  73.625(a); the Class A TV and digital Class A TV
   protection requirements in paragraph (f) of this section; the land
   mobile protection requirements of §  73.623(e); and the FM radio
   protection requirement of §  73.623(f).

   (c) The reference coordinates of a post-transition DTV allotment shall
   be the authorized transmitter site, or, where such a transmitter site
   is not available for use as a reference point, the coordinates as
   designated in the FCC order creating or modifying the post-transition
   DTV Table of Allotments.

   (d) The protected facilities of a post-transition DTV allotment shall
   be the facilities (effective radiated power, antenna height and antenna
   directional radiation pattern, if any) authorized by a construction
   permit or license, or, where such an authorization is not available for
   establishing reference facilities, the facilities designated in the FCC
   order creating or modifying the post-transition DTV Table of
   Allotments.

   (e) An application will not be accepted if it is predicted to cause
   interference to more than an additional 0.5 percent of the population
   served by another post-transition DTV station. For this purpose, the
   population served by the station receiving additional interference does
   not include portions of the population within the noise-limited service
   contour of that station that are predicted to receive interference from
   the post-transition DTV allotment facilities of the applicant or
   portions of that population receiving masking interference from any
   other station.

   (1) For evaluating compliance with the requirements of this paragraph,
   interference to populations served is to be predicted based on the 2000
   census population data and otherwise according to the procedure set
   forth in OET Bulletin No. 69: “Longley-Rice Methodology for Evaluating
   TV Coverage and Interference” (February 6, 2004) (incorporated by
   reference, see §  73.8000), including population served within service
   areas determined in accordance with §  73.622(e), consideration of
   whether F(50,10) undesired signals will exceed the following
   desired-to-undesired (D/U) signal ratios, assumed use of a directional
   receiving antenna, and use of the terrain dependent Longley-Rice
   point-to-point propagation model. Applicants may request the use of a
   cell size other than the default of 2.0 km per side, but only requests
   for cell sizes of 1.0 km per side or 0.5 km per side will be
   considered. The threshold levels at which interference is considered to
   occur are:

   (i) For co-channel stations, the D/U ratio is +15 dB. This value is
   only valid at locations where the signal-to-noise ratio is 28 dB or
   greater. At the edge of the noise-limited service area, where the
   signal-to-noise (S/N) ratio is 16 dB, this value is +23 dB. At
   locations where the S/N ratio is greater than 16 dB but less than 28
   dB, D/U values are computed from the following formula:

   D/U = 15+10log10 [1.0/(1.0−10−x/10 )]

   Where x = S/N-15.19 (minimum signal to noise ratio)

   (ii) For interference from a lower first-adjacent channel, the D/U
   ratio is −28 dB.

   (iii) For interference from an upper first-adjacent channel, the D/U
   ratio is −26 dB.

   (2) Due to the frequency spacing that exists between Channels 4 and 5,
   between Channels 6 and 7, and between Channels 13 and 14, the minimum
   adjacent channel technical criteria specified in this section shall not
   be applicable to these pairs of channels (see §  73.603(a)).

   (f) A petition to add a new channel to the post-transition DTV Table or
   a post-transition DTV station application that proposes to expand its
   allotted or authorized coverage area in any direction will not be
   accepted if it is predicted to cause interference to a Class A TV
   station or to a digital Class A TV station authorized pursuant to
   subpart J of this part, within the protected contour defined in
   §  73.6010.

   (1) Interference is predicted to occur if the ratio in dB of the field
   strength of a Class A TV station at its protected contour to the field
   strength resulting from the facilities proposed in the DTV application
   (calculated using the appropriate F(50,10) chart from Figure 9a, 10a,
   or 10c of §  73.699) fails to meet the D/U signal ratios for
   “DTV-into-analog TV” specified in §  73.623(c)(2).

   (2) Interference is predicted to occur if the ratio in dB of the field
   strength of a digital Class A TV station at its protected contour to
   the field strength resulting from the facilities proposed in the DTV
   application (calculated using the appropriate F(50,10) chart from
   Figure 9a, 10a, or 10c of §  73.699) fails to meet the D/U signal ratios
   specified in paragraph (e) of this section.

   (3) In support of a request for waiver of the interference protection
   requirements of this section, an applicant for a post-transition DTV
   broadcast station may make full use of terrain shielding and
   Longley-Rice terrain dependent propagation methods to demonstrate that
   the proposed facility would not be likely to cause interference to
   Class A TV stations. Guidance on using the Longley-Rice methodology is
   provided in OET Bulletin No. 69, which is available through the
   Internet at http://www.fcc.gov/oet/info/documents/bulletins/#69 .

   Note to §  73.616: When this rule was adopted, the filing freeze
   announced in an August 2004 public notice (19 FCC Rcd 14810 (MB 2004))
   remained in effect. For a short period of time after the filing freeze
   is lifted, until a date to be announced by a Media Bureau public
   notice, applicants must protect Appendix B facilities in addition to
   any authorized facilities required to be protected pursuant to this
   rule section.

   [ 73 FR 5682 , Jan. 30, 2008]

   return arrow Back to Top