Sec.  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  Sec. 73.623.

   (b) A petition to add a new channel to the post-transition DTV Table of
   Allotments contained in  Sec. 73.622(i) of this subpart will not be accepted
   unless  it  meets:  the  DTV-to-DTV geographic spacing requirements of
    Sec. 73.623(d)  with  respect  to  all  existing  DTV  allotments  in  the
   post-transition DTV Table; the principle community coverage requirements of
    Sec. 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
    Sec. 73.623(e); and the FM radio protection requirement of  Sec. 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
    Sec. 73.8000), including population served within service areas determined in
   accordance with  Sec. 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  Sec. 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  Sec. 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  Sec. 73.699) fails to meet the D/U signal ratios for “DTV-into-analog TV”
   specified in  Sec. 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  Sec. 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  Sec. 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]