§  25.253   Special requirements for ancillary terrestrial components
operating in the 1626.5-1660.5 MHz/1525-1559 MHz bands.

   (a) An ancillary terrestrial component in these bands shall:

   (1) In any band segment coordinated for the exclusive use of an MSS
   applicant within the land area of the U.S., where there is no other
   L-Band MSS satellite making use of that band segment within the visible
   portion of the geostationary arc as seen from the ATC coverage area,
   the ATC system will be limited by the in-band and out-of-band emission
   limitations contained in this section and the requirement to maintain a
   substantial MSS service.

   (2) In any band segment that is coordinated for the shared use of the
   applicant's MSS system and another MSS operator, where the coordination
   agreement existed prior to February 10, 2005 and permits a level of
   interference to the other MSS system of less than 6% ΔT/T, the
   applicant's combined ATC and MSS operations shall increase the system
   noise level of the other MSS to no more then 6% ΔT/T. Any future
   coordination agreement between the parties governing ATC operation will
   supersede this paragraph.

   (3) In any band segment that is coordinated for the shared use of the
   applicant's MSS system and another MSS operator, where a coordination
   agreement existed prior to February 10, 2005 and permits a level of
   interference to the other MSS system of 6% ΔT/T or greater, the
   applicant's ATC operations may increase the system noise level of the
   other MSS system by no more than an additional 1% ΔT/T. Any future
   coordination agreement between the parties governing ATC operations
   will supersede this paragraph.

   (4) In a band segment in which the applicant has no rights under a
   coordination agreement, the applicant may not implement ATC in that
   band.

   (b) ATC base stations shall not exceed an out-of-channel emissions
   measurement of -57.9 dBW/MHz at the edge of a MSS licensee's authorized
   and internationally coordinated MSS frequency assignment.

   (c) An applicant for an ancillary terrestrial component in these bands
   shall:

   (1) Demonstrate, at the time of application, how its ATC network will
   comply with the requirements of footnotes US308 and US315 to the table
   of frequency allocations contained in §  2.106 of this chapter regarding
   priority and preemptive access to the L-band MSS spectrum by the
   aeronautical mobile-satellite en-route service (AMS(R)S) and the global
   maritime distress and safety system (GMDSS).

   (2) Coordinate with the terrestrial CMRS operators prior to initiating
   ATC transmissions when co-locating ATC base stations with terrestrial
   commercial mobile radio service (CMRS) base stations that make use of
   Global Positioning System (GPS) time-based receivers.

   (3) Provide, at the time of application, calculations that demonstrate
   the ATC system conforms to the ΔT/T requirements in paragraphs (a)(2)
   and (a)(3) of this section, if a coordination agreement that
   incorporates the ATC operations does not exist with other MSS
   operators.

   (d) Applicants for an ancillary terrestrial component in these bands
   must demonstrate that ATC base stations shall not:

   (1) Exceed a peak EIRP of 31.9-10*log (number of carriers) dBW/200kHz,
   per sector, for each carrier in the 1525-1541.5 MHz and 1547.5-1559 MHz
   frequency bands;

   (2) Exceed an EIRP in any direction toward the physical horizon (not to
   include man-made structures) of 26.9-10*log (number of carriers)
   dBW/200 kHz, per sector, for each carrier in the 1525-1541.5 MHz and
   1547.5-1559 MHz frequency bands;

   (3) Exceed a peak EIRP of 23.9 −10*log(number of carriers) dBW/200 kHz,
   per sector, for each carrier in the 1541.5-1547.5 MHz frequency band;

   (4) Exceed an EIRP toward the physical horizon (not to include man-made
   structures) of 18.9-10*log(number of carriers) dBW/200 kHz, per sector,
   for each carrier in the 1541.5-1547.5 MHz frequency band;

   (5) Exceed a total power flux density level of −56.8 dBW/m2 /200 kHz at
   the edge of all airport runways and aircraft stand areas, including
   takeoff and landing paths from all carriers operating in the 1525-1559
   MHz frequency bands. The total power flux density here is the sum of
   all power flux density values associated with all carriers in a sector
   in the 1525-1559 MHz frequency band, expressed in dB(Watts/m2 /200
   kHz). Free-space loss must be assumed if this requirement is
   demonstrated via calculation;

   (6) Exceed a total power flux density level of −56.6 dBW/ m2 /200 kHz
   at the water's edge of any navigable waterway from all carriers
   operating in the 1525-1541.5 MHz and 1547.5-1559 MHz frequency bands.
   The total power flux density here is the sum of all power flux density
   values associated with all carriers in a sector in the 1525-1541.5 MHz
   and 1547.5-1559 MHz frequency bands, expressed in dB(Watts/m2 /200
   kHz). Free-space loss must be assumed if this requirement is
   demonstrated via calculation;

   (7) Exceed a total power flux density level of −64.6 dBW/ m2 /200 kHz
   at the water's edge of any navigable waterway from all carriers
   operating in the 1541.5-1547.5 MHz frequency band. The total power flux
   density here is the sum of all power flux density values associated
   with all carriers in a sector in the 1541.5-1547.5 MHz frequency band,
   expressed in dB(Watts/m2 /200 kHz). Free-space loss must be assumed if
   this requirement is demonstrated via calculation;

   (8) Exceed a peak antenna gain of 16 dBi;

   (9) Generate EIRP density, averaged over any two-millisecond active
   transmission interval, greater than −70 dBW/MHz in the 1559-1605 MHz
   band or greater than a level determined by linear interpolation in the
   1605-1610 MHz band, from −70 dBW/MHz at 1605 MHz to −46 dBW/MHz at 1610
   MHz. The EIRP, averaged over any two-millisecond active transmission
   interval, of discrete out-of-band emissions of less than 700 Hz
   bandwidth from such base stations shall not exceed −80 dBW in the
   1559-1605 MHz band or exceed a level determined by linear interpolation
   in the 1605-1610 MHz band, from −80 dBW at 1605 MHz to −56 dBW at 1610
   MHz. A root-mean-square detector function with a resolution bandwidth
   of one megahertz or equivalent and no less video bandwidth shall be
   used to measure wideband EIRP density for purposes of this rule, and
   narrowband EIRP shall be measured with a root-mean-square detector
   function with a resolution bandwidth of one kilohertz or equivalent.

   (e) Applicants for an ancillary terrestrial component in these bands
   must demonstrate, at the time of the application, that ATC base
   stations shall use left-hand-circular polarization antennas with a
   maximum gain of 16 dBi and overhead gain suppression according to the
   following:
   Angle from direction of maximum gain, in vertical plane, above antenna
   (degrees) Antenna discrimination pattern (dB)
   0 Gmax
   5 Not to Exceed Gmax −5
   10 Not to Exceed Gmax −19
   15 to 55 Not to Exceed Gmax −27
   55 to 145 Not to Exceed Gmax −30
   145 to 180 Not to Exceed Gmax −26

   Where: Gmax is the maximum gain of the base station antenna in dBi.

   (f) Prior to operation, ancillary terrestrial component licensees
   shall:

   (1) Provide the Commission with sufficient information to complete
   coordination of ATC base stations with Search-and-Rescue
   Satellite-Aided Tracking (SARSAT) earth stations operating in the
   1544-1545 MHz band for any ATC base station located either within 27 km
   of a SARSAT station, or within radio horizon of the SARSAT station,
   whichever is less.

   (2) Take all practicable steps to avoid locating ATC base stations
   within radio line of sight of Mobile Aeronautical Telemetry (MAT)
   receive sites in order to protect U.S. MAT systems consistent with
   ITU-R Recommendation ITU-R M.1459. MSS ATC base stations located within
   radio line of sight of a MAT receiver must be coordinated with the
   Aerospace and Flight Test Radio Coordinating Council (AFTRCC) for
   non-Government MAT receivers on a case-by-case basis prior to
   operation. For government MAT receivers, the MSS licensee shall supply
   sufficient information to the Commission to allow coordination to take
   place. A listing of current and planned MAT receiver sites can be
   obtained from AFTRCC for non-Government sites and through the FCC's
   IRAC Liaison for Government MAT receiver sites.

   (g) ATC mobile terminals shall:

   (1) Be limited to a peak EIRP level of 0 dBW and an out-of-channel
   emissions of −67 dBW/4 kHz at the edge of an MSS licensee's authorized
   and internationally coordinated MSS frequency assignment.

   (2) Be operated in a fashion that takes all practicable steps to avoid
   causing interference to U.S. radio astronomy service (RAS) observations
   in the 1660-1660.5 MHz band.

   (3) Not generate EIRP density, averaged over any two-millisecond active
   transmission interval, greater than −70 dBW/MHz in the 1559-1605 MHz
   band or greater than a level determined by linear interpolation in the
   1605-1610 MHz band, from −70 dBW/MHz at 1605 MHz to −46 dBW/MHz at 1610
   MHz. The EIRP, averaged over any two-millisecond active transmission
   interval, of discrete out-of-band emissions of less than 700 Hz
   bandwidth from such mobile terminals shall not exceed −80 dBW in the
   1559-1605 MHz band or exceed a level determined by linear interpolation
   in the 1605-1610 MHz band, from −80 dBW at 1605 MHz to −56 dBW at 1610
   MHz. The EIRP density of carrier-off-state emissions from such mobile
   terminals shall not exceed −80 dBW/MHz in the 1559-1610 MHz band,
   averaged over a two-millisecond interval. A root-mean-square detector
   function with a resolution bandwidth of one megahertz or equivalent and
   no less video bandwidth shall be used to measure wideband EIRP density
   for purposes of this rule, and narrowband EIRP shall be measured with a
   root-mean-square detector function with a resolution bandwidth of one
   kilohertz or equivalent.

   (h) When implementing multiple base stations and/or base stations using
   multiple carriers, where any third-order intermodulation product of
   these base stations falls on an L-band MSS band coordinated for use by
   another MSS operator with rights to the coordinated band, the MSS ATC
   licensee must notify the MSS operator. The MSS operator may request
   coordination to modify the base station carrier frequencies, or to
   reduce the maximum base station EIRP on the frequencies contributing to
   the third-order intermodulation products. The threshold for this
   notification and coordination is when the sum of the calculated signal
   levels received by an MSS receiver exceeds −70 dBm. The MSS receiver
   used in these calculations can be assumed to have an antenna with 0 dBi
   gain. Free-space propagation between the base station antennas and the
   MSS terminals can be assumed and actual signal polarizations for the
   ATC signals and the MSS system may be used.

   [ 70 FR 19319 , Apr. 13, 2005]

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