Section 73.616 - References to TV station interference protection methodology(d)Calculation of interference(1) For evaluating compliance with the requirements of this paragraph, interference to populations served is to be predicted based on the most recent official decennial U.S. Census population data as identified by the Media Bureau in a Public Notice issued not less than 60 days prior to use of the data for a specific year in application processing 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 § 73.619 , 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.73 FR 5682, Jan. 30, 2008, as amended at 83 FR 5021, Feb. 2, 2018; 83 FR 5544, Feb. 8, 2018; 86 FR 66195, Nov. 22, 2021 83 FR 5021, 3/5/2018; as amended at 83 FR 5544, 2/8/2018; 86 FR 66193, 12/22/2021; 89 FR 7245, 3/4/2024 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.