Sec. 25.201  Definitions.

    Active satellite. An earth satellite carrying a station intended to 
transmit or re-transmit radiocommunication signals.
    Base Earth Station. An earth station in the fixed-satellite service 
or, in some cases, in the land mobile-satellite service, located at a 
specified fixed point or within a specified area on land to provide a 
feeder link for the land mobile-satellite service. (RR)
    Coordination distance. For the purposes of this part, the expression 
``coordination distance'' means the distance from an earth station, 
within which there is a possibility of the use of a given transmitting 
frequency at this earth station causing harmful interference to stations 
in the fixed or mobile service, sharing the same band, or of the use of 
a given frequency for reception at this earth station receiving harmful 
interference from such stations in the fixed or mobile service.
    Earth station. A station located either on the Earth's surface or 
within the major portion of the Earth's atmosphere intended for 
communication:
    (a) With one or more space stations; or
    (b) With one or more stations of the same kind by means of one or 
more reflecting satellites or other objects in space.
    Fixed earth station. An earth station intended to be used at a 
specified fixed point.
    Fixed-Satellite Service. A radiocommunication service between earth 
stations at given positions, when one or more satellites are used; the 
given position may be a specified fixed point or any fixed point within 
specified areas; in some cases this service includes satellite-to-
satellite links, which may also be operated in the inter-satellite 
service; the fixed-satellite service may also include feeder links of 
other space radiocommunication services. (RR)
    Geostationary satellite. A geosynchronous satellite whose circular 
and direct orbit lies in the plane of the Earth's equator and which thus 
remains fixed relative to the Earth; by extension, a satellite which 
remains approximately fixed relative to the Earth.
    Inter-Satellite Service. A radiocommunication service providing 
links between artificial earth satellites.
    Land Earth Station. An earth station in the fixed-satellite service 
or, in some cases, in the mobile-satellite service, located at a 
specified fixed point or within a specified area on land to provide a 
feeder link for the mobile-satellite service. (RR)
    Land Mobile Earth Station. A mobile earth station in the land 
mobile-satellite service capable of surface movement within the 
geographical limits of a country or continent. (RR)
    Mobile earth station. An earth station intended to be used while in 
motion or during halts at unspecified points.
    Mobile-Satellite Service. A radiocommunication service:
    (1) Between mobile earth stations and one or more space stations, or 
between space stations used by this service; or
    (2) Between mobile earth stations, by means of one or more space 
stations.

    This service may also include feeder links necessary for its 
operation. (RR)
    Non-Voice, Non-Geostationary Mobile-Satellite Service. A mobile-
satellite service reserved for use by non-geostationary satellites in 
the provision of non-voice communications which may include satellite 
links between land earth stations at fixed locations.
    1.6/2.4 GHz Mobile-Satellite Service. A mobile-satellite service 
that operates in the 1610-1626.5 MHz and 2483.5-2500 MHz frequency 
bands, or in any portion thereof.
    Passive satellite. An earth satellite intended to transmit radio 
communication signals by reflection.
    Radiodetermination-Satellite Service. A radiocommunication service 
for the

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purpose of radiodetermination involving the use of one of more space 
stations. This service may also include feeder links necessary for its 
own operation. (RR)
    Satellite Digital Audio Radio Service (``DARS''). A 
radiocommunication service in which audio programming is digitally 
transmitted by one or more space stations directly to fixed, mobile, 
and/or portable stations, and which may involve complementary repeating 
terrestrial transmitters, telemetry, tracking and control facilities.
    Satellite system. A space system using one or more artificial earth 
satellites.
    Spacecraft. A man-made vehicle which is intended to go beyond the 
major portion of the Earth's atmosphere.
    Space operation service. A radiocommunication service concerned 
exclusively with the operation of spacecraft, in particular space 
tracking, space telemetry and space telecommand. These functions will 
normally be provided within the service in which the space station is 
operating.
    Space radiocommunication. Any radiocommunication involving the use 
of one or more space stations or the use of one or more reflecting 
satellites or other objects in space.
    Space station. A station located on an object which is beyond, is 
intended to go beyond, or has been beyond, the major portion of the 
Earth's atmosphere.
    Space system. Any group of cooperating earth stations and/or space 
stations employing space radiocommunication for specific purposes.
    Space telecommand. The use of radiocommunication for the 
transmission of signals to a space station to initiate, modify or 
terminate function of the equipment on a space object, including the 
space station.
    Space telemetering. The use of telemetering for the transmission 
from a space station of results of measurements made in a spacecraft, 
including those relating to the functioning of the spacecraft.
    Space tracking. Determination of the orbit, velocity or 
instantaneous position of an object in space by means of 
radiodetermination, excluding primary radar, for the purpose of 
following the movement of the object.
    Terrestrial radiocommunication. Any radiocommunication other than 
space radiocommunication or radio astronomy.
    Terrestrial station. A station effecting terrestrial 
radiocommunication.
[ 30 FR 7176 , May 28, 1965, as amended at  36 FR 2562 , Feb. 6, 1971;  48 FR 40254 , Sept. 6, 1983;  51 FR 18445 , May 20, 1986;  54 FR 49993 , Dec. 4, 
1989;  56 FR 42706 , Aug. 29, 1991;  58 FR 68059 , Dec. 23, 1993;  59 FR 53329 , Oct. 21, 1994;  62 FR 11105 , Mar. 11, 1997]