§  25.213   Inter-Service coordination requirements for the 1.6/2.4 GHz
mobile-satellite service.

   (a) Protection of the radio astronomy service in the 1610.6-1613.8 MHz
   band against interference from 1.6/2.4 GHz Mobile-Satellite Service
   systems.

   (1) Protection zones. All 1.6/2.4 GHz Mobile Satellite Service systems
   shall be capable of determining the position of the user transceivers
   accessing the space segment through either internal radiodetermination
   calculations or external sources such as LORAN-C or the Global
   Positioning System. During periods of radio astronomy observations,
   land mobile earth stations shall not operate when located within
   geographic protection zones defined by the radio observatory
   coordinates and separation distances as follows:

   (i) In the band 1610.6-1613.8 MHz, within a 160 km radius of the
   following radio astronomy sites:
         Observatory        Latitude (DMS) Longitude (DMS)
   Arecibo, PR                    18 20 46        66 45 11
   Green Bank Telescope, WV       38 25 59        79 50 24
                                  38 26 09        79 49 42
   Very Large Array, NM           34 04 43       107 37 04
   Owens Valley, CA               37 13 54       118 17 36
   Ohio State, OH                 40 15 06        83 02 54

   (ii) In the band 1610.6-1613.8 MHz, within a 50 km radius of the
   following sites:
     Observatory    Latitude (DMS) Longitude (DMS)
   Pile Town, NM          34 18 04       108 07 07
   Los Alamos, NM         35 46 30       106 14 42
   Kitt Peak, AZ          31 57 22       111 36 42
   Ft. Davis, TX          30 38 06       103 56 39
   N. Liberty, IA         41 46 17        91 34 26
   Brewster, WA           48 07 53       119 40 55
   Owens Valley, CA       37 13 54       118 16 34
   St. Croix, VI          17 45 31        64 35 03
   Mauna Kea, HI          19 48 16       155 27 29
   Hancock, NH            42 56 01        71 59 12

   (iii) Out-of-band emissions of a mobile earth station licensed to
   operate within the 1610.0-1626.5 MHz band shall be attenuated so that
   the power flux density it produces in the 1610.6-1613.8 MHz band at any
   radio astronomy site listed in paragraph (a)(1) (i) or (ii) of this
   section shall not exceed the emissions of a mobile earth station
   operating within the 1610.6-1613.8 MHz band at the edge of the
   protection zone applicable for that site. As an alternative, a mobile
   earth station shall not operate during radio astronomy observations
   within the 1613.8-1615.8 MHz band within 100 km of the radio astronomy
   sites listed in paragraph (a)(1)(i) of this section, and within 30 km
   of the sites listed in paragraph (a)(1)(ii) of this section, there
   being no restriction on a mobile earth station operating within the
   1615.8-1626.5 MHz band.

   (iv) For airborne mobile earth stations operating in the 1610.0-1626.5
   MHz band, the separation distance shall be the larger of the distances
   specified in paragraph (a)(1) (i), (ii) or (iii) of this section, as
   applicable, or the distance, d, as given by the formula:

   d (km) = 4.1 square root of (h)

   where h is the altitude of the aircraft in meters above ground level.

   (v) Smaller geographic protection zones may be used in lieu of the
   areas specified in paragraphs (a)(1) (i), (ii), (iii), and (iv) of this
   section if agreed to by the Mobile-Satellite Service licensee and the
   Electromagnetic Spectrum Management Unit (ESMU), National Science
   Foundation, Washington, D.C. upon a showing by the Mobile-Satellite
   Service licensee that the operation of a mobile earth station will not
   cause harmful interference to a radio astronomy observatory during
   periods of observation.

   (vi) The ESMU shall notify Mobile-Satellite Service space station
   licensees authorized to operate mobile earth terminals in the
   1610.0-1626.5 MHz band of periods of radio astronomy observations. The
   mobile-satellite systems shall be capable of terminating operations
   within the frequency bands and protection zones specified in paragraphs
   (a)(1) (i) through (iv) of this section, as applicable, after the first
   position fix of the mobile earth terminal either prior to transmission
   or, based upon its location within the protection zone at the time of
   initial transmission of the mobile earth terminal. Once the
   mobile-satellite system determines that a mobile earth terminal is
   located within an RAS protection zone, the mobile-satellite system
   shall immediately initiate procedures to relocate the mobile earth
   terminal operations to a non-RAS frequency.

   (vii) A beacon-actuated protection zone may be used in lieu of fixed
   protection zones in the 1610.6-1613.8 MHz band if a coordination
   agreement is reached between a mobile-satellite system licensee and the
   ESMU on the specifics of beacon operations.

   (viii) Additional radio astronomy sites, not located within 100 miles
   of the 100 most populous urbanized areas as defined by the United
   States Census Bureau at the time, may be afforded similar protection
   one year after notice to the mobile-satellite system licensees by
   issuance of a public notice by the Commission.

   (2) Mobile-Satellite Service space stations transmitting in the
   1613.8-1626.5 MHz band shall take whatever steps necessary to avoid
   causing harmful interference to the radio astronomy facilities listed
   in paragraphs (a)(1)(i) and (ii) of this section during periods of
   observation.

   (3) Mobile-Satellite Service space stations operating in the
   2483.5-2500 MHz frequency band shall limit spurious emission levels in
   the 4990-5000 MHz band so as not to exceed −241 dB (W/m2 /Hz) at the
   surface of the Earth.

   (4) The Radioastronomy Service shall avoid scheduling radio astronomy
   observations during peak MSS/RDSS traffic periods to the greatest
   extent practicable.

   (b) If a Mobile-Satellite Service space station operator in the
   2496-2500 MHz band intends to operate at powers levels that exceed the
   PFD limits in §  25.208(v), or if actual operations routinely exceed
   these PFD limits, we require the Mobile-Satellite Service operator to
   receive approval from each operational BRS system in the affected
   geographical region.

   [ 59 FR 53329 , Oct. 21, 1994, as amended at  61 FR 9945 , Mar. 12, 1996;
    67 FR 61816 , Oct. 2, 2002;  71 FR 35188 , June 19, 2006]

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