Sec.  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
    Sec. 73.3555.

   (3) In determining compliance with  Sec. 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.
   Guidance for use of the ILLR model for these purposes is provided in OET
   Bulletin No. 72. This document is available through the Internet on the FCC
   Home Page at http://www.fcc.gov. 

   (e) In the case of measurements to determine the eligibility of individual
   households to receive satellite retransmission of distant network signals
   under the copyright law provisions of 17 U.S.C. 119(d)(10), if a satellite
   carrier  and  the  network  station  or  stations  asserting  that the
   retransmission of a signal of a distant network station is prohibited are
   unable to agree on a person to conduct the test, the American Radio Relay
   League, Inc., 225 Main Street, Newington, CT 06111–1494, shall designate the
   person  or organization to conduct measurements based on the technical
   qualifications and independence of proposed testers. The satellite carrier
   and network station shall propose testers and provide their qualifications
   in writing to the American Radio Relay League (ARRL). Individuals may also
   volunteer themselves as testers by submitting their qualifications to the
   ARRL. The ARRL can be reached by telephone at 860–594–0200, or email at
   hq@arrl.org. 

   (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).

   [ 44 FR 36039 , June 20, 1979, as amended at  47 FR 35990 , Aug. 18, 1982;  50 FR 23699 , June 5, 1985;  50 FR 32416 , Aug. 12, 1985;  65 FR 36641 , June 9, 2000;
    70 FR 21670 , Apr. 27, 2005]