§ 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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