§ 25.259   Time sharing between NOAA meteorological satellite systems and
non-voice, non-geostationary satellite systems in the 137-138 MHz band.

   (a) The space stations of a non-voice, non-geostationary Mobile-Satellite
   Service (NVNG MSS) system time-sharing downlink spectrum in the 137-138 MHz
   band with National Oceanic and Atmospheric Administration (NOAA) satellites
   shall  not  transmit  signals  into the “protection areas” of the NOAA
   satellites.

   (1) With respect to transmission in the 137.333-137.367 MHz, 137.485-137.515
   MHz, 137.605-137.635 MHz, and 137.753-137.787 MHz bands, the protection area
   for a NOAA satellite is the area on the Earth's surface in which the NOAA
   satellite is in line of sight from the ground at an elevation angle of five
   degrees or more above the horizon. No NVNG MSS satellite shall transmit in
   these  bands when it is in line of sight at an elevation angle of zero
   degrees or more from any point on the ground within a NOAA satellite's
   protected area for that band.

   (2) With respect to transmission in the 137.025-137.175 MHz and 137.825-138
   MHz bands, the protection area for a NOAA satellite is the area on the
   Earth's surface in which the NOAA satellite is in line of sight from the
   ground at any elevation angle above zero degrees. No NVNG MSS satellite
   shall transmit in these bands when at a line-of-sight elevation angle of
   zero degrees or more from any point on the ground within a NOAA satellite's
   protected area for that band. In addition, such an NVNG MSS satellite shall
   cease  transmitting when it is at an elevation angle of less than zero
   degrees from any such point, if reasonably necessary to protect reception of
   the NOAA satellite's signal.

   (3) An NVNG MSS licensee is responsible for obtaining the ephemeris data
   necessary for compliance with these restrictions. The ephemeris information
   must be updated system-wide on at least a weekly basis. For calculation
   required for compliance with these restrictions an NVNG MSS licensee shall
   use an orbital propagator algorithm with an accuracy equal to or greater
   than the NORAD propagator used by NOAA.

   (b) An NVNG licensee time sharing spectrum in the 137-138 MHz band must
   establish a 24-hour per day contact person and telephone number so that
   claims  of  harmful  interference  into  NOAA earth stations and other
   operational issues can be reported and resolved expeditiously. This contact
   information must be made available to NOAA or its designee. If the NTIA
   notifies the Commission that NOAA 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 NOAA system.
   An 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
   NOAA  in  the  137-138 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.

   [ 62 FR 59296 , Nov. 3, 1997, as amended at  78 FR 8430 , Feb. 6, 2013;  79 FR 8324 , Feb. 12, 2014]

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