Sec. 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

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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:

                                                                        
------------------------------------------------------------------------
                                                   Latitude    Longitude
                   Observatory                       (DMS)       (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:

                                                                        
------------------------------------------------------------------------
                                                   Latitude    Longitude
                   Observatory                       (DMS)       (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.

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    (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) Protection of the radionavigation-satellite service. Mobile 
earth stations operating in the 1610-1626.5 MHz band shall limit out-of-
band emissions in the 1574.397-1576.443 MHz band so as not to exceed an 
e.i.r.p. density level of -70 dB (W/MHz) averaged over any 20 ms period. 
The e.i.r.p. of any discrete spurious emission (i.e., bandwidth less 
than 600 Hz) in the 1574.397-1576.443 MHz band shall not exceed -80 dBW.
[ 59 FR 53329 , Oct. 21, 1994, as amended at  61 FR 9945 , Mar. 12, 1996]