§ 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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