Glossary Terms

A means of narrowcast transmission of video, voice and data by SCPA means to a satellite, typically used in business applications.

The band in the 500 to 900 MHz range, including TV channels 14 through 83.

Satellite component that receives, amplifies, and retransmits a TV signal or perhaps many narrower-band data or audio channels.

Ground facility used to interface with a satellite during communications.

TDM digital channel carrier (1.544 MBPS)

Any set of standard procedures that permit devices to intercommunicate.

The process of superimposing an information signal onto a carrier for transmission.

Acronym for MOdulator-DEModulator. A device that modulates and demodulates signals. Note: Modems are primarily used for converting digital signals into quasi-analog signals for transmission over analog communication channels and for reconverting the quasi-analog signals into digital signals.

A data communications system that (a) lies within a limited spatial area, (b) has a specific user group, (c) has a specific topology, and (d) is not a public switched telecommunications network, but may be connected to one.

The range of frequencies between 11 and 14 GHz used increasingly by communications satellites.

Integrated Receiver/Decoder

A network that provides end-to-end digital connectivity to support a wide range of services, including voice and non-voice services, to which users have access by a limited set of standard multi-purpose user network interfaces, as defined in the ITU-T1 series.

That mode of operation in which communication between two terminals occurs in either direction but in only one direction at a time. Contrast with duplex or simplex operation. Note: Half-duplex operation may occur on half-duplex circuits or on duplex circuits, but it may not occur on simplex circuits.

Frequency Modulation

A circuit switched operational mode for transferring (transporting and switching) user information through a network. Contrast with packet switching mode.

A band of frequencies used for satellite and terrestrial communications. The range of frequencies from 4 to 6 gigaHertz (billion cycles per second) is used by most communications satellites.

A sequence of eight adjacent binary digits usually treated as a unit.

Data represented by a physical quantity that is considered to be continuously variable and whose magnitude is made directly proportional to the data or to a suitable function of the data.

To transmit to a satellite for relay; also, the dish used to transmit.

That mode of operation in which communication between two points occurs in only one direction at a time. Contrast with half duplex or duplex operation.