Sec.  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  Sec. 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/m ^2 /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/m ^2 /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/ m ^2 /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/m ^2 /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/ m ^2 /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/m ^2
   /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 discrimination pattern (dB)
        antenna (degrees)
------------------------------------------------------------------------
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]