Don't know your DVR from MHz? You've come to the right place. Satelliteusa.com explains the difference between bits and bytes and all the satellite terminology you need to understand how satellite TV is better than cable.
- Amplifier - A device used to boost the strength of an electronic signal.
- Amplitude Modulation (AM) - A form of modulation in which the amplitude of a carrier wave is varied in direct proportion to that of a modulating signal and the frequency remains constant. See also Frequency Modulation.
- Analog - A form of transmitting information using continuously variable quantities. An analog signal is responsive to changes in light, sound, heat and pressure. See also Digital.
- Antenna - A device for transmitting and receiving radio waves that comes in many shapes depending on operating frequency and use.
- Artifact - The effects seen on a TV screen caused by errors in a digital signal. See also Cliff Effect.
- Attenuation - The loss in power of electromagnetic signals between transmission and reception points.
- Backbone - The primary path of connectivity in a distribution system.
- Bandwidth - A measure of spectrum or a range of frequencies. For digital signals, bandwidth is also used to mean the amount of data that can be transferred through a digital connection in a given time period (in other words, the connection's bit rate, measured in bits or bytes per second).
- Baud - A unit measuring the rate of information flow, with five baud roughly equivalent to one alphanumeric character. Today most digital signals are measured as bits per second.
- Bird - Slang for a communications satellite located in geosynchronous orbit.
- Bit - Short for binary digit, the most basic unit of information.
- Bit Error Rate - The fraction of a sequence of message bits that are in error.
- Bit Rate - The speed of a digital transmission, measured in bits per second.
- Blanking Interval - The portion of a TV signal between when each frame is sent. Not viewable by the human eye.
- Broadcast - The distribution of audio and video signals to a large group.
- Byte - A sequence of eight adjacent binary digits usually treated as a unit. 1 byte = 8 bits; 1 Kbyte = 1,024 bytes; 1Mbyte = 1,024 Kbytes; 1Gbyte = 1,024 Mbytes.
- C Band - The band between 4 and 8 GHz. The 6 GHz and 4 GHz bands are used for satellite communications.
- Carrier to Noise Ratio (C/N) - The ratio of the received carrier power and the noise power in a given bandwidth, expressed in dB. The higher the C/N, the better the received picture.
- Carrier � Either the organization that provides communications and networking services or the alternating current that establishes boundaries in which a signal is transmitted.
- Channel - A frequency band in which a specific broadcast signal is transmitted.
- Clarke Orbit - The circular orbit in space where geosynchronous satellites are placed. It is 22,237 miles from the surface of the earth, directly "above" the equator. See also Geosynchronous.
- Cliff effect - The sudden breakdown or loss of digital signal reception when it contains more errors than the error correction system can cope with. Up to this point there is no degradation in reception quality; a significant advantage over analog where there is a gradual deterioration.
- Codec - Coder/decoder system for digital transmission. A device or program capable of transforming a stream or signal.
- Co-location (or colocation) - When multiple satellites share orbital space but use different frequency bands or channel.
- Common Carrier - A common carrier is an organization that transports a product or service using its facilities, or those of other carriers.
- Compression - A technique to reduce the amount of data to be transmitted that reduces the amount of bandwidth needed to transmit video or audio, thus increasing the capacity of a satellite transponder.
- Cross Modulation - A form of signal distortion in which modulation from one or more RF carrier(s) is imposed on another carrier.
- DBS - See Direct Broadcast Satellite.
- Decoder - A television set-top device which decodes an electronically scrambled television picture into a viewable signal from the satellite system. Also known as a Descrambler.
- Delay - The time it takes for a signal to go from the sending station through the satellite to the receiving station.
- Demodulator - A satellite receiver circuit that extracts or demodulates the signals from the carrier.
- Descrambler: See Decoder.
- Digital Broadcast - Conversion of information into bits of data for transmission through wire, fiber optic cable, satellite, or over air techniques using discrete bits of information in a certain order. Digital signals allow for simultaneous transmission of voice, data or video. See also Analog.
- Direct broadcast satellite - Service that uses satellites to broadcast multiple channels of television programming directly to home mounted small-dish antennas. Abbreviated DBS.
- Direct To Home (DTH) - Reception of satellite programs with a satellite dish in an individual home.
- DirecTivo - TiVO brand DVR adapted for use with DirecTV service.
- Downlink - The satellite-to-earth path of a 2-way satellite link. Often used to describe the receiving dish end of the link. See also Uplink.
- DTV - Abbreviation for Digital Television
- Echo Effect - A time-delayed electronic reflection of a signal. This is largely eliminated by modern digital echo cancellers.
- Elevation - The angle of the satellite antenna relative to the horizon. A satellite elevation angle is zero if pointed at the horizon and 90 degrees when pointing straight up.
- Encoder - A device used to electronically alter a signal so that it can only be viewed on a receiver equipped with a special decoder. See also Decoder.
- F/D - Ratio of antenna focal length to antenna diameter. A higher ratio means a shallower satellite dish.
- Focal Length - Distance from the center feed to the center of the satellite dish.
- Focal Point - The area on the dish to which the primary reflector concentrates the received satellite signal.
- Frequency - The number of times in one second that an alternating current goes through its complete cycle. One cycle per second is also referred to as one hertz.
- Frequency Modulation (FM) - A form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. Satellite carriers operating in the analog mode are usually frequency modulated. See also Amplitude Modulation.
- Geostationary satellite - A geosynchronous satellite angle with zero inclination, which makes the satellite appear to hover over one spot on the earth's equator.
- Geosynchronous Orbit - The orbit located 22,237 miles above the surface of the earth where satellites are stationed.
- Gigahertz (GHz) - One billion cycles per second
- Hertz (Hz) - The basic measure of radio frequency characteristics. An electromagnetic wave completes a full oscillation from its positive to its negative pole and back again in what is known as a cycle. A Hertz is equal to one cycle per second.
- Hub - The master station through which all communications to, from and between micro terminals must flow.
- Inclination - The angle between the orbital plane of a satellite and the equatorial plane of the earth.
- INTELSAT - Abbreviation for the International Telecommunications Satellite Organization, which operates a network of satellites for international transmissions.
- Interference - Energy which tends to interfere with the reception of the desired signals, such as fading from airline flights, RF interference from adjacent channels, or ghosting from reflecting objects such as mountains and buildings.
- ITU - Abbreviation for the International Telecommunication Union, which develops international technical standards for communications equipment including satellites.
- Jammer - A device designed to disrupt or block communications signals.
- Ka Band - The frequency range from 18 to 31 GHz.
- Kbps - Kilobits per second. Refers to transmission speed of 1,000 bits per second.
- Kilohertz (kHz) - One thousand (1,000) cycles per second.
- Master Antenna Television (MATV) - An antenna system that serves a concentration of television sets such as in apartment buildings, hotels or motels.
- Megahertz (MHz) - One million cycles per second.
- Microwave Interference - Interference which occurs when an earth station aimed at a distant satellite picks up a second, often stronger signal, from a local telephone terrestrial microwave relay transmitter. Microwave interference can also be produced by nearby radar transmitters as well as the sun itself. Relocating the satellite dish by only several feet will often completely eliminate the microwave interference.
- Modulation - The process of manipulating the frequency or amplitude of a carrier in relation to an incoming video, voice or data signal.
- Modulator - A component in satellite transponders that modulates the signal so it can be read.
- Multicast - A subset of broadcast that extends concept of "broadcasting" by allowing the sending of one transmission to many users in a defined group, but not necessarily to all users in that group.
- Noise - Any unwanted and unmodulated energy that is always present to some extent within any signal.
- Noise Figure (NF) - A term which is a figure of merit of a device, which compares the device with a theoretical "perfect" device.
- Orbital Period - The time that it takes a satellite to complete one circumnavigation of its orbit.
- Outage - A malfunction of the communications system that prevents the user from receiving satellite service.
- Parabolic Antenna - A satellite antenna in the shape of the dish described mathematically as a parabola. The parabolic shape focuses the weak microwave signal hitting the surface of the dish into a single focal point in front of the dish.
- Polar Orbit - An orbit parallel to polar axis of the earth
- Protocol - Any set of standard procedures that permit devices to communicate with each other.
- Radio Frequency Interference - A term used to denote apparent disturbance or distortion to satellite signals. Abbreviated RFI
- Rain Outage - Loss of signal due to absorption and increased sky-noise temperature caused by heavy rainfall.
- Receiver - An electronic device which enables a particular satellite signal to be separated from all others being received by an earth station, and converts the signal format into a format for video, voice or data.
- Receiver Sensitivity - Measure of power needed by the detector to achieve a specific baseband performance, such as a specified bit error rate or S/N ratio.
- RFI - See Radio Frequency Interference.
- Router - A device that forwards digital packets of information from one network to another.
- Satellite - A sophisticated electronic communications relay station that transmits signals from a point on earth back to a larger area on earth. Satellites orbit 22,237 miles above the equator, moving in a fixed orbit at the same speed and direction of the earth (about 7,000 mph east to west).
- Scrambler - A device used to electronically alter a signal so that it can only be viewed on a receiver equipped with a special decoder.
- Signal to Noise Ratio (S/N) - The ratio of the signal power and noise power. A video S/N of 54 to 56 dB is considered to be an excellent S/N, that is, of broadcast quality. A video S/N of 48 to 52 dB is considered to be a good S/N at the headend for Cable TV.
- Single-Channel-Per-Carrier (SCPC - A method used to transmit a large number of signals over a single satellite transponder.
- Snow - A form of noise picked up by a television receiver caused by a weak signal. Snow is characterized by alternate dark and light dots appearing randomly on the picture tube. To eliminate snow, a more sensitive receive antenna must be used, or better amplification must be provided in the receiver (or both). Satellite TV service doesn't have any snow.
- Solar Outage - An outage that occurs when the sun passes near or behind the satellite and within the field of view of the antenna. This field of view is usually wider than the beamwidth.
- Spectrum - The range of electromagnetic radio frequencies used in transmission of voice, data and television.
- Spillover - Satellite signal that falls on locations outside the beam pattern's defined edge of coverage.
- Telemetry, Tracking and Control - The facility which monitors and controls the proper functioning of a satellite in space. Abbreviated TT&C.
- Transceiver - A combination transmitter and receiver.
- Transmitter - An electronic device containing an oscillator and modulator that produces electromagnetic wave signal for transmission by an antenna.
- Transponder - A part contained in a satellite that is a combination receiver, frequency converter, and transmitter package. Communications satellites typically have between 12 and 24 onboard transponders.
- TVRO - Abbreviation for Television Receive Only. The satellite receiving antenna used in small home systems.
- Ultra High Frequency (UHF) - The band in the 500 to 900 MHz range, including TV channels 14 through 83.
- Unicast - Transmission of a copy of every packet to every receiver.
- Uplink - Transmission from earth to a satellite. See also Downlink.
- Very High Frequency - Abbreviated VHF. The band in the 30 to 300 MHz range, including TV channels 2 through 13.
- VSAT - Abbreviation for Very Small Aperture Terminal. Refers to small earth stations, usually in the 1.2 to 2.4 meter range.
- Wavelength - The distance while traveling at the speed of light that a radio wave will travel during a single cycle.
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