Sec.  21.902   Interference.

   

   (a) All applicants, conditional licensees, and licensees shall make
   exceptional efforts to avoid harmful interference to other users and
   to avoid blocking potential adjacent channel use in the same city and
   cochannel use in nearby cities. In areas where major cities are in
   close proximity, careful consideration should be given to minimum
   power requirements and to the location, height, and radiation pattern
   of the transmitting antenna. Licensees, conditional licensees, and
   applicants are expected to cooperate fully in attempting to resolve
   problems of potential interference before bringing the matter to the
   attention of the Commission.

   (b) As a condition for use of frequency in this service, each
   applicant, conditional licensee, and licensee is required to:

   (1) Not enter into any lease or contract or otherwise take any action
   that would unreasonably prohibit location of another station's
   transmitting antenna at any given site inside its own protected
   service area.

   (2) Cooperate fully and in good faith to resolve interference and
   transmission security problems.

   (3) Engineer the system to provide at least 45 dB of cochannel
   interference protection within the 56.33 km (35 mile) protected
   service area of any authorized or previously-proposed ITFS or
   incumbent MDS station, and at each previously-registered ITFS receive
   site registered as of September 17, 1998 (or the appropriate value for
   bandwidths other than 6 MHz.)

   (4) Engineer the station to provide at least 0 dB of adjacent channel
   interference protection within the 56.33 km (35 mile) protected
   service area of any authorized or previously-proposed ITFS or
   incumbent MDS station, and at each previously-registered ITFS receive
   site registered as of September 17, 1998 (or the appropriate value for
   bandwidths other than 6 MHz.)

   (5)(i) Engineer the station to limit the calculated free space power
   flux density to -73 dBW/m 2 (or the appropriate value for bandwidth
   other than 6 MHz) at the boundary of a 56.33 km (35 mile) protected
   service area, where there is an unobstructed signal path from the
   transmitting antenna to the boundary; or alternatively, obtain the
   written consent of the entity authorized for the adjoining area to
   exceed the -73 dBW/m 2 limiting signal strength at the common
   boundary.

   (ii) In determining signal path conditions, the following shall be
   used: a 9.1 meter (30 feet) receiving antenna height, the transmitting
   antenna height, terrain elevations and 4/3 earth radius propagation
   conditions.

   (6) If a proposed station is within 80 km (50 miles) of the Canadian
   or Mexican border, the station must be designed to meet the
   requirements set forth in international treaties.

   (7) Notwithstanding the above, main, booster and response stations
   shall use the following formulas, as applicable, for determining
   compliance with: (1) Radiated field contour limits where bandwidths
   other than 6 MHz are employed at stations utilizing digital emissions;
   and (2) Cochannel and adjacent channel D/U ratios where the bandwidths
   in use at the interfering and protected stations are unequal and both
   stations are utilizing digital modulation or one station is utilizing
   digital modulation and the other station is utilizing either 6 MHz
   NTSC analog modulation or 125 kHz analog modulation (I channels only).

   (i) Contour limit: -73 dBW/m 2 + 10 log(X/6) dBW/m 2 , where X is the
   bandwidth in MHz of the digital channel.

   (ii) Co-channel D/U: 45 dB + 10 log(X[1]/X[2]) dB, where X[1] is the
   bandwidth in MHz of the protected channel and X[2] is the bandwidth in
   MHz of the interfering channel.

   (iii) Adjacent channel D/U: 0 dB + 10 log(X[1]/X[2]), dB where X[1] is
   the bandwidth in MHz of the protected channel and X[2] is the
   bandwidth in MHz of the interfering channel.

   (c) The following interference studies must be prepared:

   (1) An analysis of the potential for harmful interference within the
   56.33 km (35 mile) protected service areas of any authorized or
   previously proposed incumbent station:

   (i) If the coordinates of the applicant's proposed transmitter are
   within 160.94 km (100 miles) of the center coordinates of any
   authorized or previously proposed incumbent station with protected
   service area of 56.33 km (35 miles) as specified in Sec. 21.902(d); or

   (ii) If the great circle path between the applicant's proposed
   transmitter and the protected service area of any authorized, or
   previously-proposed, cochannel or adjacent-channel station(s) is
   within 241.4 kilometers or less and 90 percent or more of the path is
   over water or within 16.1 kilometers of the coast or shoreline of the
   Atlantic Ocean, the Pacific Ocean, the Gulf of Mexico, any of the
   Great Lakes, or any bay associated with any of the above (see
   Sec. Sec. 21.901(a) and 74.902 of this chapter);

   (2) Applicants may design interference studies in any manner that
   demonstrates the avoidance of harmful interference, as defined in this
   subpart.

   (i) In lieu of interference studies, applicants may submit in
   accordance with Sec. 21.938 a written statement of no objection to the
   operation of the MDS station.

   (ii) The Commission may direct applicants to submit interference
   studies of a specific nature.

   (3) Except for new stations proposed in applications filed after
   September 15, 1995, in the case of a proposal to operate a
   non-colocated station within the protected service area of an
   authorized, or previously proposed, adjacent channel station, an
   analysis that identifies the areas within the protected service areas
   of both the authorized or previously proposed adjacent channel station
   and the proposed station that cannot be protected as specified in
   Sec. 21.902(b)(4) and an explanation of why the proposed station cannot be
   colocated with the existing or previously proposed station.

   (4) In the case of a proposal for use of channel 2, an analysis of the
   potential for harmful interference with any authorized point-to-point
   station located within 80.5 kilometers (50 miles) which utilizes the
   2160-2162 MHz band; and

   (d)(1) Subject to the limitations contained in paragraph (e) of this
   section, each MDS station licensee shall be protected from harmful
   electrical interference, as determined by the theoretical
   calculations, within a protected service area of which the boundary
   will be 56.3255 kilometers (35 miles) from the transmitter site.

   (2) As of September 15, 1995, the location of these protected service
   area boundaries shall become fixed. The center of the circular area
   shall be the geographic latitude and longitude of the transmitting
   antenna site specified in station authorizations or previously
   proposed applications filed at the Commission before September 15,
   1995. Subsequent transmitter site changes will not change the location
   of the 56.3255 kilometers (35 mile) protected service area boundaries.

   (e) No MDS licensee will be protected from harmful interference caused
   by:

   (1) Any station with an earlier filing date.

   (2) Any station that was authorized before July 1984.

   (3) Any multichannel MDS station whose application was pending on
   September 9, 1983.

   (f) In addressing potential harmful interference in this service, the
   following definitions, procedures and other criteria shall apply:

   (1) Cochannel interference is defined as the ratio of the desired
   signal to the undesired signal present in the desired channel, at the
   output of a reference receiving antenna oriented to receive the
   maximum desired signal. Harmful interference will be considered
   present when a calculation using a terrain sensitive signal
   propagation model determines that this ratio is less than 45 dB (or
   the appropriate value for bandwidths other than 6 MHz.)

   (2) Adjacent channel interference is defined as the ratio of the
   desired signal to undesired signal present in an adjacent channel, at
   the output of a reference receiving antenna oriented to receive the
   maximum desired signal level.

   (i) Harmful interference will be considered present when a calculation
   using a terrain sensitive model determines that this ratio is less
   than 0dB (or the appropriate value for bandwidths other than 6 MHz.)

   (ii) In the alternative, harmful interference will be considered
   present for an ITFS station constructed before May 26, 1983, when a
   calculation using a terrain-sensitive propagation model determines
   that this ratio is less than 10 dB (or the appropriate value for
   bandwidths other than 6 MHz.) unless:

   (A) The individual receive site under consideration has been
   subsequently upgraded with up-to-date reception equipment, in which
   case the ratio shall be less than 0 dB. Absent information presented
   to the contrary, however, the Commission will assume that reception
   equipment installation occurred simultaneously with original station
   equipment; or

   (B) The license for an MDS station is conditioned on the proffer to
   the affected ITFS station licensee of equipment capable of providing a
   ratio of 0 dB or more at no expense to the ITFS station licensee, and
   also conditioned, if necessary, on the proffer of installation of such
   equipment; and there has been no showing by the affected ITFS station
   licensee demonstrating good cause and that the proposed equipment will
   not provide a ratio of 0 dB or more, or that installation of such
   equipment, at no expense to the ITFS station licensee, is not possible
   or has not been proffered.

   (3) For purposes of this section all interference calculations
   involving receive antenna performance shall use the reference antenna
   characteristics shown in figure 1.
   [ec01mr91.040.gif]

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   (4) For purposes of this section, the received signal power level
   (RSL)[dBW] at the output of the FCC reference receiving antenna is
   obtained from the following formulas (or an equivalent adaptation):

   (RSL)[dBW]=(EIRP)[dBW] -(L[FS])[dB]+(G[AR])[dB]

   where the free space loss (L[FS]) is

   (L[FS])[dB]=20 log (4[d]/)[dB]

   in which the parameters are defined as follows:

   (RSL)[dBW] is the received power in decibels referenced to one watt.

   (EIRP)[dBW] is the equivalent isotropically radiated power in decibels
   above one watt.

   d is the distance of the signal path in meters.

   l is the wavelength of the signal in meters.

   G[AR] is the dB gain of the reference receiving antenna above an
   isotropic antenna (obtained from Figure 1 of this section.)

   (5) A determination of signal path conditions shall use a 9.1 meters
   (30 feet) receiving antenna height, the transmitting antenna height,
   terrain elevation, and assume 4/3 earth radius propagation conditions.

   (6) An application will not be accepted for filing if cochannel or
   adjacent channel interference is predicted at the boundary of the
   56.33 km (35 mile) protected service area of an authorized or
   previously proposed incumbent station based on the following criteria:

   (i) Interference calculations shall be made only for directions where
   there is an unobstructed signal path from the site of a proposed
   station to the boundary of any protected area.

   (ii) Calculations of received power levels in units of dBW from the
   proposed station will be made at one degree intervals around the
   protected service area.

   (iii) The assumed value of the desired signal level at the boundary of
   an incumbent station shall be -83 dBW, which is the calculated
   received power in free space at a distance of 56.33 km (35 miles),
   given at EIRP of 2000 watts and a receiver antenna gain of 20 dBi.

   (iv) Harmful interference will be considered to occur at locations
   along the boundary wherever the ratio between the desired signal level
   of -83 dBw and the received power from a proposed cochannel or
   adjacent channel station is less than 45 dB or 0 dB for cochannel or
   adjacent channel proposals, respectively.

   (7) Alternatively, MDS applications will be accepted on the basis of
   an executed written interference agreement between potentially
   affected parties filed in accordance with Sec. 21.938.

   (g)(1) All interference studies prepared pursuant to paragraph (c) of
   this section must be served on all licensees, conditional licensees,
   and applicants for the stations required to be studied by this
   section. This service must include a copy of the FCC application and
   occur on or before the date the application is filed with the
   Commission.

   (2) MDS licensees, conditional licensees and applicants of facilities
   with 56.33 km (35 mile) protected service areas shall notify in
   writing the holders of authorizations for adjoining BTAs or PSAs of
   application filings for modified station licenses, provided the
   proposed facility would produce an unobstructed signal path to any
   location within the adjoining BTA or PSA. This service must include a
   copy of the FCC application and occur on or before the date the
   application is filed with the Commission.

   (h) For purposes of Sec. 21.31(a), an MDS application, except for those
   applications filed on or after September 15, 1995, filed for a
   facility that would cause harmful electrical interference within the
   protected service area of any authorized or previously proposed
   station will be presumed to be mutually exclusive with the application
   for such authorized or previously proposed station.

   (i)(1) For each application for a new station, or amendment thereto,
   proposing MDS facilities, filed on October 1, 1995, or thereafter, on
   or before the day the application or amendment is filed, the applicant
   must prepare an analysis demonstrating that operation of the MDS
   applicant's transmitter will not cause harmful electrical interference
   to each receive site registered as of September 17, 1998, nor within a
   protected service area as defined in paragraph (d)(1) of this section,
   of any cochannel or adjacent channel ITFS station licensed, with a
   conditional license, or proposed in a pending application on the day
   such MDS application is filed, with an ITFS transmitter site within 50
   miles of the coordinates of the MDS station's proposed transmitter
   site.

   (2) For each application described in paragraph (i)(1) of this
   section, the applicant must serve, by certified mail, return receipt
   requested, on or before the day the application or amendment described
   in paragraph (i)(1) of this section is filed initially with the
   Commission, a copy of the complete MDS application or amendment,
   including each exhibit and interference study, described in paragraph
   (i)(1) of this section, on each ITFS licensee, conditional licensee,
   or applicant described in paragraph (i)(1) of this section.

   (3) For each application described in paragraph (i)(1) of this
   section, the applicant must certify and file, with the application or
   amendment, its certification of its compliance with the requirements
   of paragraph (i)(2) of this section.

   (4) For each application described in paragraph (i)(1) of this
   section, the applicant must file with the Commission in Washington,
   DC, on or before the 30th day after the application or amendment
   described in paragraph (i)(1) of this section is filed initially with
   the Commission, a written notice which contains the following:

   (i) Caption--ITFS Service Notice;

   (ii) Applicant's name, address, proposed service area and channel
   group, and application file number, if known;

   (iii) A list of each ITFS licensee and conditional licensee described
   in paragraph (i)(1) of this section;

   (iv) The address used for service to each ITFS licensee and
   conditional licensee described in paragraph (i)(1) of this section;
   and

   (v) A list of the date each ITFS licensee and conditional licensee
   described in paragraph (i)(1) of this section received a copy of the
   complete application or amendment described in paragraph (i)(1) of
   this section; or a notation of lack of receipt by the ITFS licensee or
   conditional licensee of a copy of the complete application or
   amendment, on or before such 30th day, together with a description of
   the applicant's efforts for receipt by each such licensee or
   conditional licensee lacking receipt of the application.

   (5) The public notices described in paragraph (i)(6) of this section
   are as follows:

   (i) For initial applications for new MDS stations which participate in
   a lottery, this public notice is the notice announcing the selection
   of the applicant's application by lottery for qualification review.

   (ii) For initial applications for new MDS stations which participate
   in a competitive bidding process, this public notice is the notice
   announcing the application of the winning bidder in the competitive
   bidding process has been accepted for filing.

   (iii) For initial applications for new MDS stations which do not
   participate in a lottery or a competitive bidding process, this public
   notice is the notice announcing that the applicant's application is
   not mutually-exclusive with other MDS applications.

   (iv) For MDS modification applications, this public notice is the
   notice announcing that the modification application has been accepted
   for filing.

   (6)(i) Notwithstanding the provisions of Sections 1.824(c) and
   21.30(a)(4), for each application described in paragraph (i)(1) of
   this section, each ITFS licensee and each ITFS conditional licensee
   described in paragraph (i)(1) of this section may file with the
   Commission, on or before the 30th day after the public notice
   described in paragraph (i)(5) of this section, a petition to deny the
   MDS application.

   (ii) Except for the requirements as to the filing time deadline, this
   petition to deny must otherwise comply with the provisions of Section
   21.30.

   (iii) In addition, this ITFS petition to deny must:

   (A) Identify the subject MDS application, including the applicant's
   name, station location, channel group, and application file number;

   (B) Include a certificate of service demonstrating service on the
   subject MDS applicant by certified mail, return receipt requested, on
   or before the 30th day after the MDS public notice described in
   paragraph (i)(5) of this section;

   (C) Include a demonstration that it made efforts to reach agreement
   with the MDS applicant but was unable to do so;

   (D) Include an engineering analysis that operation of the proposed MDS
   station will cause harmful interference to its ITFS station;

   (E) Include a demonstration, in those cases in which the MDS
   applicant's analysis is dependent upon modification(s) to the ITFS
   facility, that the harmful interference cannot be avoided by the
   proposed substitution of new or modified equipment to be supplied and
   installed by the MDS applicant, at no expense to the ITFS licensee or
   conditional licensee; and

   (F) Be limited to raising objections concerning the potential for
   harmful interference to its ITFS station, or concerning a failure by
   the MDS applicant to serve the ITFS licensee or conditional licensee
   with a copy of the complete application or amendment described in
   paragraph (i)(1) of this section.

   (iv) The Commission will presume an ITFS licensee or conditional
   licensee described in paragraph (i)(1) of this section has no
   objection to operation of the MDS station, if the ITFS licensee or
   conditional licensee fails to file a petition to deny by the deadline
   prescribed in paragraph (i)(6)(i) of this section.

   (j) If the initial application for facilities in the 2596-2644
   frequency band was filed on September 9, 1983, an applicant proposing
   to modify such facilities must include with its modification
   application:

   (1) An analysis demonstrating that the modification will not increase
   the size of the geographic area suffering harmful interference within
   the protected service area of existing or proposed co-channel or
   adjacent-channel facilities in the 2596-2644 MHz frequency band with a
   transmitter site within 80.5 km (50 miles) of the modifying station's
   transmitter site of the initial application for the interfered-with
   station was filed on September 9, 1983; and

   (2) An analysis demonstrating that the modification will not cause
   harmful interference to any new portion of the protected service area
   of existing or proposed co-channel or adjacent-channel facilities in
   the 2596-2644 frequency band with a transmitter site within 80.5 km
   (50 miles) of the modifying station's transmitter site, if the initial
   application for the interfered-with station was filed on September 9,
   1983.

   (k) If an initial application for facilities in the 2596-2644
   frequency band was filed on September 9, 1983, a licensee proposing to
   modify a constructed station may request exclusion from the
   interference analysis prescribed at Sec. 21.902(c) (1) and (2) with
   respect to another specified application for E or F channel
   facilities, if the modifying licensee files as part of its
   modification application a demonstration that:

   (1) The MDS application for which exclusion is requested was proposed
   by an initial application filed on September 9, 1983;

   (2) The MDS application for which exclusion is requested is not yet
   perfected by the submission of the information necessary for
   processing, as of the date of filing of the modification application;
   and

   (3) A copy of the licensee's modification application, including the
   demonstration specified in this paragraph, was served on the MDS
   applicant for which exclusion is requested, on or before the date of
   filing of the modification application.

   (l) Specific rules relating to response station hubs, booster
   stations, and 125 kHz channels are set forth in Sec. Sec. 21.909, 21.913,
   21.940, 74.939 of this chapter, 74.940 of this chapter and 74.985 of
   this chapter. To the extent those specific rules are inconsistent with
   any rules set forth above, those specific rules shall control.

   (m) The following information formats and storage media are to be used
   in connection with applications for new and modified MDS and ITFS
   stations:

   (1) The data file prepared for submission to the Commission's
   Reference Room pursuant to the requirements set out at paragraph 74 of
   Appendix D to the Report and Order in MM Docket 97-217, FCC 98-231,
   must be in ASCII format on either CD-ROMs or 3.5" diskettes. Any
   supplementary information submitted in connection with Appendix D may
   be in either ASCII or PDF format (graphics must be in PDF format) on
   either CD-ROMs or 3.5" diskettes. Applicants serving such
   data/information on other applicants and/or licensees should do so
   using the same format(s) and media as used in their submission to the
   Commission's Reference Room.

   (2) Demonstrations and certifications prepared for submission to the
   Commission's Reference Room may be in either hard copy or in ASCII or
   PDF format on CD-ROM's or 3.5" diskettes. (Graphics must be either
   hard copy or PDF format) Applicants serving such demonstrations and
   certifications on other applicants and/or licensees should do so using
   the same format(s) and media as used in their submission to the
   Commission's Reference Room.

   [ 44 FR 60534 , Oct. 19, 1979, as amended at  48 FR 33901 , July 26, 1983;
    49 FR 25479 , June 21, 1984;  52 FR 27556 , July 22, 1987;  55 FR 46010 ,
   Oct. 31, 1990;  56 FR 57598 , Nov. 13, 1991;  56 FR 57818 , Nov. 14, 1991;
    56 FR 65191 , Dec. 16, 1991;  58 FR 11798 , Mar. 1, 1993;  58 FR 44895 ,
   Aug. 25, 1993;  60 FR 36553 , July 17, 1995;  60 FR 36739 , July 18, 1995;
    60 FR 57367 , Nov. 15, 1995;  61 FR 18098 , Apr. 24, 1996;  61 FR 26676 ,
   May 28, 1996;  63 FR 65102 , Nov. 25, 1998;  64 FR 63731 , Nov. 22, 1999;
    65 FR 46617 , July 31, 2000]

   Effective Date Note:   At  65 FR 46617 , July 31, 2000, Sec. 21.902 was
   amended by adding paragraph (m). This paragraph contains information
   collection and recordkeeping requirements and will not become
   effective until approval has been given by the Office of Management
   and Budget.