47 CFR 73.683 – Field strength contours and presumptive determination of field strength at individual locations
(a) In the authorization of TV stations, two field strength contours are considered. These are specified as Grade A and Grade B and indicate the approximate extent of coverage over average terrain in the absence of interference from other television stations. Under actual conditions, the true coverage may vary greatly from these estimates because the terrain over any specific path is expected to be different from the average terrain on which the field strength charts were based. The required field strength, F (50,50), in dB above one micro-volt per meter (dBu) for the Grade A and Grade B contours are as follows:
| Grade A (dBu) | Grade B (dBu) | |
|---|---|---|
| Channels 2-6 | 68 | 47 |
| Channels 7-13 | 71 | 56 |
| Channels 14-69 | 74 | 64 |
(b) It should be realized that the F (50,50) curves when used for Channels 14-69 are not based on measured data at distances beyond about 48.3 kilometers (30 miles). Theory would indicate that the field strengths for Channels 14-69 should decrease more rapidly with distance beyond the horizon than for Channels 2-6, and modification of the curves for Channels 14-69 may be expected as a result of measurements to be made at a later date. For these reasons, the curves should be used with appreciation of their limitations in estimating levels of field strength. Further, the actual extent of service will usually be less than indicated by these estimates due to interference from other stations. Because of these factors, the predicted field strength contours give no assurance of service to any specific percentage of receiver locations within the distances indicated. In licensing proceedings these variations will not be considered.
(c) The field strength contours will be considered for the following purposes only:
(1) In the estimation of coverage resulting from the selection of a particular transmitter site by an applicant for a TV station.
(2) In connection with problems of coverage arising out of application of § 73.3555.
(3) In determining compliance with § 73.685(a) concerning the minimum field strength to be provided over the principal community to be served.
(d) For purposes of determining the eligibility of individual households for satellite retransmission of distant network signals under the copyright law provisions of 17 U.S.C. § 119(d)(10)(A), field strength shall be determined by the Individual Location Longley-Rice (ILLR) propagation prediction model. Such eligibility determinations shall consider only the signals of network stations located in the subscriber’s Designated Market Area. Guidance for use of the ILLR model in predicting the field strength of analog television signals for such determinations is provided in OET Bulletin No. 72 (stations operating with analog signals include some Class A stations licensed under part 73 of this chapter and some licensed low power TV and TV translator stations that operate under part 74 of this chapter). Guidance for use of the ILLR model in predicting the field strength of digital television signals for such determinations is provided in OET Bulletin No. 73 (stations operating with digital signals include all full service stations and some Class A stations that operate under part 73 of this chapter and some low power TV and TV translator stations that operate under Part 74 of this chapter). OET Bulletin No. 72 and OET Bulletin No. 73 are available through the Federal Communications Commission’s Reference Information Center, or at the FCC’s Office of Engineering and Technology (OET) website: https://www.fcc.gov/oet/info/documents/bulletins/.
(e) If a location was predicted to be unserved by a local network station using a version of the ILLR model specified in OET Bulletin No. 72 or OET Bulletin No. 73, as appropriate, and the satellite subscriber at that location is receiving a distant signal affiliated with the same network from its satellite provider, the satellite subscriber shall remain eligible for receiving the distant signal from its satellite provider if that location is subsequently predicted to be served by the local station due to either a change in the ILLR model or a change in the station’s operations that change its coverage.
(f) A satellite carrier is exempt from the verification requirements of 47 U.S.C. § 339(c)(4)(A) with respect to a test requested by a satellite subscriber to whom the retransmission of the signals of local broadcast stations is available under 47 U.S.C. § 338 from such carrier. The definitions of satellite carrier, subscriber, and local market contained in 47 CFR 76.66(a) apply to this paragraph (f).