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A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z Alphanumeric – the combination of letters and numbers AM – amplitude modulation Analog – signal transmission method using a continuous electrical signal that varies in amplitude or frequency. AOR – Atlantic Ocean Region ARF – Alternate Recovery Facility Asymmetric Circuit – a two-way satellite link with inbound and outbound paths set at different rates Azimuth – angle of elevation between ground and antenna center beam. Backbone Network – transmission facility that interconnects Internet distribution channels. Backhaul – point-to-point transmission from a base station and a communications network. Bandwidth – range of frequencies needed to carry a signal without distortion. Baud – a unit measuring the rate of information flow or signaling speed. BGP 4 Routing – routing procedure that allows traffic to be sent via one route and received over another, such as terrestrial phone lines then satellite. Bird – a communications satellite Body Stabilized – the satellite control system that allows the entire body of the satellite to hold a fixed orientation toward the earth. BPSK – Binary Phase Shift Keying; a digital modulation scheme used in transmission communications. Broadcast – delivery of transmission using electronic media. C C-band – frequency that operates from 4 to 6 GHz. Used by most communications satellites and requires larger ground antennas. Carrier – communications company providing circuits to carry private traffic. CDV – Compressed Digital Video Cellular – the current technology that serves the majority of mobile telephony needs. It operates at ultra high frequency, and used a system of radio "cells" a few miles across which are interfaced by small, low power radio telephones. Collocation – placement of equipment at common physical site to reduce environmental and financial impact and network deployment. Common Carrier – The FCC's class of transmission systems, such as telephone, telegraph and certain satellites, open to public use at uniform fees and generally not permitted to control content. Compression – a term used to denote reducing the amount of bandwidth needed to transmit video or audio, increasing the capacity of a satellite transponder. COMSAT – Communications Satellite Corporation, chartered by Congress as an exclusive provider of international telecommunications satellite channels to the US. Cross Polarization – allows two separate signals, one vertical and the other horizontal to exist on the same frequency and pass independently of each other. CW – Continuous Wave, a signal consisting of a single frequency. D DAMA – Demand Assigned Multiple Access, contention access schemes that allow multiple communications users to share a discrete portion of the bandwidth. DB – decibel, an analog unit of measure of signal strength, volume, or signal loss due to resistance as expressed in logarithmic form. DBS – Direct Broadcast Satellite, a high-powered satellite that transmits TV signals directly to dishes at viewers' home. Demodulation – the process for retrieving an information signal that has been modulated onto a carrier. Despun – the orientation of a satellite antenna that keeps it pointed to the earth. Also used to refer to the communications payload section of a Hughes spinning satellite. Digital – a method of storing, processing and transmitting data with electronic or optical pulses in the form of the binary digits 0 or 1. Digital Switching – the process where connections are based on digital signals without converting them to analog signals. Downlink – to receive from a satellite to the earth station. DSS – Digital Satellite System Duplex – two-way transmission Earth Station – equipment on the ground that sends and receives signals to and from satellites. EIRP – Effective Isotropic Radiated Power Elevation – the angle measured between earth and the direction of the antenna. Exchange – switching center Facilities-Based Carrier – interexchange carriers that own their network facilities and transmission lines. FCC – Federal Communications Commission, an independent federal governmental agency authorized by the Communications Act of 1934 to regulate interstate and foreign communications. FDM – Frequency Division Multiplex, space-division multiplexing technique in which the available transmission frequency range of a given circuit is divided into narrower bands each used to carry a separate conversation. FDMA – Frequency Division Multiple Access, digital transmission technology that combines elements of TDMA and spread spectrum. Fiber Optics – transmission system using clear glass fiber strands to carry multiple voice circuits as light pulses. FM – Frequency Modulation, covers 88-108 MHz on the broadcast band. Footprint – signal coverage area of a satellite. Frame Relay – transport technology that organizes data into units called frames instead of providing dedicated channels. Frequency – the rate at which current alternates. FSS – Fixed Satellite Service Full Duplex – a circuit that permits transmission in two directions simultaneously. GHz – GigaHertz, a unit of frequency equal to one billion cycles per second. Geostationary Satellite – satellite that orbits at 24,000 miles from ground, because the satellite follows a geosynchronous orbit they appear to be stationary in the sky. Geosynchronous Satellite – satellite that travels around the earth approximately 22,300 miles from ground at the same rate that the earth turns. GPS – Global Positioning System, a series of 24 geosynchronous satellites that continuously transmit their position. Used for personal tracking, navigation and automatic vehicle location technologies. Ground Segment – facility that includes a feeder-link earth station, a network communications controller and a network operations center. Half Duplex – a circuit capable of transmission in two directions but not at the same time. HDTV – High Definition Television, digital television signals transmitted in the very high frequency band providing a finer and wider TV picture. Headend – a cable TV system's control center where incoming signals from satellites and other sources are put onto outgoing channels. HPA – High Power Amplifier, equipment used to amplify signals. Hub – a network operations center Hybrid Satellite – a satellite that carries two or more different communications payloads such as C and Ku-band. Hz – Hertz, cycle per second; a measure of electromagnetic frequency that represents the number of complete cycles per second. ILEC – Incumbent Local Exchange Carrier, the historic local phone service provider, distinct from CLECs. Intelsat – International Telecommunications Satellite Organization, formed in 1964 to create a worldwide satellite system. Interconnect – any company other than the local phone company that supplies equipment for connection to phone company lines by sale lease or rent. Interconnect Facility – communication link used to provide local area communication service between locations, to form a node in the network. Interface – a bounded area between two pieces of equipment where all signals passed through are carefully defined. Interoperability – the ability of a network to operate with other networks with different protocols or technologies. IOR – Indian Ocean Region ISDN – Integrated Services Digital Network, provides consistent and clear communications using an end-to-end digital network with higher speed data connections and more bandwidth for data transfer. ISP – Internet Service Provider Ka-Band – Frequency that operates from 18 to 31 GHz. Ku-Band – Frequency that operates from 11 to 14 GHz. Is used commonly by communications satellites and requires smaller ground antennas. LAN – Local Area Network, standard communications architecture, usually referring to computer communications. LEO – Low Earth Orbit, for satellites that are placed less than 22,300 miles above earth. Local Loop – the connection between the central office and the customer, linking local subscribers to the local telco's central office. MBPS – Megabits Per Second MCPC – Multi-Channel Per Carrier MEO – Medium Earth Orbit, for satellites that are 10,000 or more miles above earth. MHz – Megahertz, one million cycles per second. Microwave Band – frequencies from 1 GHz or more that use microwave for point-to-point and multipoint communications. Modem – modulates discontinuous digital signals into continuous analog waves for transmission over analog circuits then demodulates the waves into digital bit streams at the receiving end of the circuit. Modulation – superimposing an information signal (frequency, amplitude and phase) onto a carrier for transmission. MMDS – Multichannel Multipoint Distribution Service – uses omnidirectional microwave signals to deliver video programs to subscribers Multiplexer – device that combines several communication channels into a single circuit. Network – series of points connected by communications channels. Node – a termination point for two or more communications links. Point-to-Point – circuit that connects two points directly with no intermediate processing nodes. POR – Pacific Ocean Region Protocol – set of standard procedures that permit devices to intercommunicate. PSTN – Public Switched Telephone Network PTT – postal, telegraph and telephone organizations that run foreign communication systems. Receiver – converts a signal to whatever type of signal is needed to transmit. Redundancy – providing redundant or backup components to ensure uninterrupted operation of a system in case of failing. RFI – Radio Frequency Interference, denotes apparent disturbance to satellite signals. Router – a device that supports connectivity by transporting information to their destination. RPM – Revolutions Per Minute Satellite – a radio relay station that orbits the earth for point-to-multipoint distribution. Shared Hub – a satellite communications operations center that is shared among a number of separate network users. Simplex – One-way transmissions Simulcast – signal transmission that broadcasts the same signal over each site in a network. Spot Beams – the focusing of energy from a satellite to the ground to concentrate the limited available effective radiated power. Sun Outage – when the sun passes behind a satellite in relation to the earth and the sun's energy momentarily interferes with the satellite signals. This event happens during spring and fall equinox. Suppression – signal in a communications channel, maritime vessel portable terminals. Switch – equipment that establishes and routes communication paths between separate extensions. Symmetric Circuit – two-way satellite link with inbound and outbound paths set at the same rates. T1 – circuit for digital transmission equal to 1.544 megs. TCP/IP – Transmission Control Protocol/Internet Protocol, TCP governs the exchange of sequential data, IP routes outing and recognizes incoming messages. TDMA – Time Division Multiple Access, a method of accessing a satellite using time separation, sending simultaneous data streams interleaved using a clock to separate the various data packets. Telecommunications – communication process for transmission of information from a sender to a receiver by means of electromagnetic or lightwave medium. Teleconferencing – using audio, video and computer equipment to permit geographically separated individuals to participate in a meeting or discussion. Telephony – the transmission of voice over a network. Teleport – technical ground facility used for satellite communications. Terrestrial – earth, land or ground based telecommunications systems. Tiering – combining cable channels to sell at a package price. Transceiver – combination of a transmitter and a receiver. Transponder – a satellite component that receives communication signals from earth's surface and the frequency conversion, amplification and retransmission of signals back to earth.
V-Band – frequency that operates from 40 – 60 GHz. VPN – Virtual Private Network, allows users to create their own private information network. VSAT – Very Small Aperture Terminal, satellite dishes much smaller than conventional dishes for installation at end-user locations. Wireless – using the radio-frequency spectrum or microwave
network for voice, data, Internet and video
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