§  90.545   TV/DTV interference protection criteria.

   Public safety base, control, and mobile transmitters in the 769-775 MHz
   and 799-805 MHz frequency bands must be operated only in accordance
   with the rules in this section, to reduce the potential for
   interference to public reception of the signals of existing TV and DTV
   broadcast stations transmitting on TV Channels 62, 63, 64, 65, 67, 68
   or 69.

   (a) D/U ratios. Licensees of public safety stations must choose site
   locations that are a sufficient distance from co-channel and adjacent
   channel TV and DTV stations, and/or must use reduced transmitting power
   or transmitting antenna height such that the following minimum desired
   signal to undesired signal ratios (D/U ratios) are met:

   (1) The minimum D/U ratio for co-channel stations is 40 dB at the
   hypothetical Grade B contour (64 dBµV/m) (88.5 kilometers or 55.0
   miles) of the TV station or 17 dB at the equivalent Grade B contour (41
   dBµV/m) (88.5 kilometers or 55.0 miles) of the DTV station.

   (2) The minimum D/U ratio for adjacent channel stations is 0 dB at the
   hypothetical Grade B contour (64 dBµV/m) (88.5 kilometers or 55.0
   miles) of the TV station or −23 dB at the equivalent Grade B contour
   (41 dBµV/m) (88.5 kilometers or 55.0 miles) of the DTV station.

   (b) Maximum ERP and HAAT. The maximum effective radiated power (ERP)
   and the antenna height above average terrain (HAAT) of the proposed
   land mobile base station, the associated control station, and the
   mobile transmitters shall be determined using the methods described in
   this section.

   (1) Each base station is limited to a maximum ERP of 1000 watts.

   (2) Each control station is limited to a maximum ERP of 200 watts and a
   maximum HAAT of 61 m. (200 ft).

   (3) Each mobile station is limited to a maximum ERP of 30 watts and a
   maximum antenna height of 6.1 m. (20 ft.).

   (4) Each portable (handheld) transmitter is limited to a maximum ERP of
   3 watts.

   (5) All transmitters are subject to the power reductions given in
   Figure B of §  90.309 of this chapter, for antenna heights higher than
   152 meters (500 ft).

   (c) Methods. The methods used to calculate TV contours and antenna
   heights above average terrain are given in § §  73.683 and 73.684 of this
   chapter. Tables to determine the necessary minimum distance from the
   public safety station to the TV/DTV station, assuming that the TV/DTV
   station has a hypothetical or equivalent Grade B contour of 88.5
   kilometers (55.0 miles), are located in §  90.309 and labeled as Tables
   B, D, and E. Values between those given in the tables may be determined
   by linear interpolation. The locations of existing and proposed TV/DTV
   stations during the transition period are given in part 73 of this
   chapter and in the final proceedings of MM Docket No. 87-268. The DTV
   allotments are:
      State         City     NTSC TV Ch. DTV Ch. ERP (kW) HAAT (m)
   California   Stockton              64      62     63.5      874
   California   Los Angeles           11      65    688.7      896
   California   Riverside             62      68    180.1      723
   California   Concord               42      63     61.0      856
   Pennsylvania Allentown             39      62     50.0      302
   Pennsylvania Philadelphia           6      64   1000.0      332
   Pennsylvania Philadelphia          10      67    791.8      354
   Puerto Rico  Aguada                50      62     50.0      343
   Puerto Rico  Mayaguez              16      63     50.0      347
   Puerto Rico  Naranjito             64      65     50.0      142
   Puerto Rico  Aguadilla             12      69    691.8      665

   The transition period is scheduled to end on December 31, 2006. After
   that time, unless otherwise directed by the Commission, public safety
   stations will no longer be required to protect reception of co-channel
   or adjacent channel TV/DTV stations.

   (1) Licensees of stations operating within the ERP and HAAT limits of
   paragraph (b) must select one of three methods to meet the TV/DTV
   protection requirements, subject to Commission approval:

   (i) utilize the geographic separation specified in the tables
   referenced below;

   (ii) Submit an engineering study justifying the proposed separations
   based on the parameters of the land mobile station and the parameters,
   including authorized and/or applied for facilities, of the TV/DTV
   station(s) it is trying to protect; or,

   (iii) obtain written concurrence from the applicable TV/DTV station(s).
   If this method is chosen, a copy of the agreement must be submitted
   with the application.

   (2) The following is the method for geographic separations.

   (i) Base stations having an antenna height (HAAT) less than 152 m. (500
   ft.) shall afford protection to co-channel and adjacent channel TV/DTV
   stations in accordance with the values specified in Table B (co-channel
   frequencies based on 40 dB protection) and Table E (adjacent channel
   frequencies based on 0 dB protection) in §  90.309 of this part. For
   base stations having an antenna height (HAAT) between 152-914 meters
   (500-3,000 ft.) the effective radiated power must be reduced below 1
   kilowatt in accordance with the values shown in the power reduction
   graph in Figure B in §  90.309 of this part. For heights of more than
   152 m. (500 ft.) above average terrain, the distance to the radio path
   horizon will be calculated assuming smooth earth. If the distance so
   determined equals or exceeds the distance to the hypothetical or
   equivalent Grade B contour of a co-channel TV/DTV station ( i.e., it
   exceeds the distance from the appropriate Table in §  90.309 to the
   relevant TV/DTV station) an authorization will not be granted unless it
   can be shown in an engineering study (method 2) that actual terrain
   considerations are such as to provide the desired protection at the
   actual Grade B contour (64 dBµV/m for TV and 41 dBµV/m for DTV
   stations), or that the effective radiated power will be further reduced
   so that, assuming free space attenuation, the desired protection at the
   actual Grade B contour (64 dBµV/m for TV and 41 dBµV/m coverage contour
   for DTV stations) will be achieved. Directions for calculating powers,
   heights, and reduction curves are listed in §  90.309 for land mobile
   stations. Directions for calculating coverage contours are listed in
   § §  73.683-685 for TV stations and in §  73.625 for DTV stations.

   (ii) Control and mobile stations (including portables) are limited in
   height and power and therefore shall afford protection to co-channel
   and adjacent channel TV/DTV stations in accordance with the values
   specified in Table D (co-channel frequencies based on 40 dB protection)
   in §  90.309 of this part and a minimum distance of 8 kilometers (5
   miles) from all adjacent channel TV/DTV station hypothetical or
   equivalent Grade B contours (adjacent channel frequencies based on 0 dB
   protection for TV stations and—23 dB for DTV stations). Since control
   and mobile stations may affect different TV/DTV stations than the
   associated base station, particular care must be taken by applicants to
   ensure that all the appropriate TV/DTV stations are considered ( e.g.,
   a base station may be operating on TV Channel 64 and the mobiles on TV
   Channel 69, in which case TV Channels 63, 64, 65, 68, and 69 must be
   protected). Since mobiles and portables are able to move and
   communicate with each other, licensees or coordinators must determine
   the areas where the mobiles can and cannot roam in order to protect the
   TV/DTV stations, and advise the mobile operators of these areas and
   their restrictions.

   (iii) In order to protect certain TV/DTV stations and to ensure
   protection from these stations which may have extremely large contours
   due to unusual height situations, an additional distance factor must be
   used by all public safety base, control and mobile stations. For all
   co-channel and adjacent channel TV/DTV stations which have an HAAT
   between 350 and 600 meters, public safety stations must add the
   following DISTANCE FACTOR to the value obtained from the referenced
   Tables in §  90.309 and to the distance for control and mobile stations
   on adjacent TV/DTV channels (96.5 km).

   DISTANCE FACTOR = (TV/DTV HAAT−350) ÷ 14 in kilometers, where HAAT is
   the TV or DTV station antenna height above average terrain obtained
   from its authorized or proposed facilities, whichever is greater.

   (iv) For all co-channel and adjacent channel TV/DTV stations which have
   an antenna height above average terrain greater than 600 meters, public
   safety stations must add 18 kilometers as the DISTANCE FACTOR to the
   value obtained from the referenced Tables in §  90.309 and to the
   distance for control and mobile stations on adjacent TV/DTV channels
   (96.5 km).

   Note to §  90.545: The 88.5 km (55.0 mi) Grade B service contour (64
   dBµV/m) is based on a hypothetical TV station operating at an effective
   radiated power of one megawatt, a transmitting antenna height above
   average terrain of 610 meters (2000 feet) and the Commission's R-6602
   F(50,50) curves. See §  73.699 of this chapter. Maximum facilities for
   TV stations operating in the UHF band are 5 megawatts effective
   radiated power at an antenna HAAT of 610 meters (2,000 feet). See
   §  73.614 of this chapter. The equivalent contour for DTV stations is
   based on a 41 dBµV/m signal strength and the distance to the F(50,90)
   curve. See §  73.625 of this chapter.

   [ 63 FR 58651 , Nov. 2, 1998, as amended at  65 FR 53646 , Sept. 5, 2000;
    69 FR 59536 , Oct. 4, 2004;  72 FR 67577 , Nov. 29, 2007]

   return arrow Back to Top