§ 25.260   Time sharing between DoD meteorological satellite systems and
non-voice, non-geostationary satellite systems in the 400.15-401 MHz band.

   (a) The space stations of a non-voice, non-geostationary Mobile-Satellite
   Service (NVNG MSS) system time-sharing downlink spectrum in the 400.15-401.0
   MHz band with Department of Defense (DoD) satellites shall not transmit
   signals into the “protection areas” of the DoD satellites.

   (1) The protection area for such a DoD satellite is the area on the Earth's
   surface in which the DoD satellite is in line of sight from the ground at an
   elevation angle of five degrees or more above the horizon.

   (2) An NVNG MSS space station shall not transmit in the 400.15-401 MHz band
   when at a line-of-sight elevation angle of zero degrees or more from any
   point on the ground within the protected area of a DoD satellite operating
   in that band.

   (3) An NVNG MSS licensee is responsible for obtaining the ephemeris data
   necessary for compliance with this restriction. The ephemeris information
   must be updated system-wide at least once per week. For calculation required
   for compliance with this restriction an NVNG MSS licensee shall use an
   orbital propagator algorithm with an accuracy equal to or greater than the
   NORAD propagator used by DoD.

   (b) An NVNG licensee time sharing spectrum in the 400.15-401 MHz band must
   establish a 24-hour per day contact person and telephone number so that
   claims of harmful interference into DoD earth stations and other operational
   issues can be reported and resolved expeditiously. This contact information
   must be made available to DoD or its designee. If the NTIA notifies the
   Commission that DoD is receiving unacceptable interference from a NVNG
   licensee, the Commission will require such NVNG licensee to terminate its
   interfering  operations  immediately  unless  it  demonstrates  to the
   Commission's reasonable satisfaction, and that of NTIA, that it is not
   responsible for causing harmful interference into the worldwide DoD system.
   A NVNG licensee assumes the risk of any liability or damage that it and its
   directors, officers, employees, affiliates, agents and subcontractors may
   incur or suffer in connection with an interruption of its Mobile-Satellite
   Service, in whole or in part, arising from or relating to its compliance or
   noncompliance with the requirements of this paragraph.

   (c) Each satellite in a NVNG licensee's system time-sharing spectrum with
   DoD  in the 400.15-401 MHz band shall automatically turn off and cease
   satellite transmissions if, after 72 consecutive hours, no reset signal is
   received from the NVNG licensee's gateway earth station and verified by the
   satellite. All satellites in such NVNG licensee's system shall be capable of
   instantaneous  shutdown  on  any  sub-band upon command from such NVNG
   licensee's gateway earth station.

   (d)  Initially,  a NVNG licensee time-sharing spectrum with DoD in the
   400.15-401 MHz band shall be able to change the frequency on which its
   system satellites are operating within 125 minutes of receiving notification
   from a DoD required frequency change in the 400.15-401 MHz band. Thereafter,
   when a NVNG licensee constructs additional gateway earth stations located
   outside  of  North and South America, it shall use its best efforts to
   decrease  to  90 minutes the time required to implement a DoD required
   frequency change. A NVNG licensee promptly shall notify the Commission and
   NTIA of any decrease in the time it requires to implement a DoD required
   frequency change.

   (e) Once a NVNG licensee time-sharing spectrum with DoD in the 400.15-401
   MHz  band demonstrates to DoD that it is capable of implementing a DoD
   required frequency change within the time required under paragraph (d) of
   this  section,  thereafter,  such  NVNG licensee shall demonstrate its
   capability to implement a DoD required frequency change only once per year
   at the instruction of DoD. Such demonstrations shall occur during off-peak
   hours, as determined by the NVNG licensee, unless otherwise agreed by the
   NVNG  licensee and DoD. Such NVNG licensee will coordinate with DoD in
   establishing a plan for such a demonstration. In the event that a NVNG
   licensee fails to demonstrate to DoD that it is capable of implementing a
   DoD  required frequency change in accordance with a demonstration plan
   established by DoD and the NVNG licensee, upon the Commission's receipt of a
   written notification from NTIA describing such failure, the Commission shall
   impose  additional  conditions  or requirements on the NVNG licensee's
   authorization  as  may  be  necessary to protect DoD operations in the
   400.15-401 MHz downlink band until the Commission is notified by NTIA that
   the NVNG licensee has successfully demonstrated its ability to implement a
   DoD required frequency change. Such additional conditions or requirements
   may  include,  but  are  not  limited to, requiring such NVNG licensee
   immediately to terminate its operations interfering with the DoD system.

   [ 62 FR 59296 , Nov. 3, 1997, as amended at  78 FR 8430 , Feb. 6, 2013;  79 FR 8325 , Feb. 12, 2014]

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