A switch that selects one of two inputs (A or B) for routing to a common output while providing adequate isolating between the two signals.

Analog/Digital (Conversion).

Analog to Digital Conversion. Process of sampling and coding an analog quantity or signal or produce a digital representation.

Alternating Current.

Adjacent - Channel Interference

A system used to verify that a MIDI connection is working, that involves the sending device, sending frequent short messages to the receiving device to reassure it that all is well.Not all MIDI devices support active sensing.

A system for generating waveforms or sounds by combining basic waveforms or sampled sounds prior to further processing with filters and envelope shapers.

Adaptive Delta Modulation. Digital coding method employed by Dolby Labs' satellite TV audio system, to be used (via B-MAC) by Australia's HACBSS.

Envelope generator with Attack, Sustain, Decay and Release parameters. This is a simple type of envelope generator and was first used on early analogue synthesizers. This form of envelope generator continues to be popular on modern instruments.

Acronym for Audio Engineering Society, one of the industry's professional audio associations.

A two-channel interface used to pass digital audio between equipment. It is often known as the AES-EBU interface.. It carries two digital audio channels plus embedded clocking data on a balanced cable of a nominal 110 Ohm impedance, with up to 24 bits per sample and sample rates up to 384kHz.

An extension to the AES 3 standard, which describes an unbalanced version of the interface using BNC connectors and 75 Ohm video cables.

A circuit which locks an electronic component onto a chosen frequency.

"After Fade listen; a system used within mixing consoles to allow specific signals to be monitored at the level set by their fader of level control knob. Aux sends are generally monitored AFL rather than PFL "

"A means of generating a control signal based on how much pressure is applied to the keys of a MIDI keyboard. "

A circuit that uses feedback to maintain the output of an electronic component at a constant level.

(Ampere) Unit of electrical current

Device that increases the level of an electrical signal.

Refer to sound levels or electrical signal levels.

"Circuitry that uses a continually changing voltage or current to represent a signal. The origin of the term is that the electrical signal can be thought of as being 'analogous' to the original signal. "

"American Standard Code for Information Interchange. A standard code for representing computer keyboard characters by binary data."

Signals in the human audio range:nominally 20Hz to 20kHz.

Mixer inputs used to add effects to the mix.

Physical output from a mixer Aux Send buss.

"Control on a mixing console designed to route a proportion of the channel signal to the effects or cue mix outputs (Aux Send)."

Ability of a wire, cable or material to resist surface wear.

The coldest possible temperature at which all molecular motion ceases. It is expressed in degrees Kelvin as measured from absolute zero. Zero degrees Kelvin equals minus 273.16 °C or minus 459 °F.

A test in which voltage, temperature, etc. are increased above normal operating values to obtain observable deterioration in a relatively short period of time. The plotted results give expected service life under normal conditions.

Describes a circuit containing transistors, ICs, tubes and other devices, that require power to operate and are capable of amplification.

An adjacent channel is immediately next to another channel in frequency.

The measure of the ease with which an alternating current flows in a circuit. The reciprocal of impedance.

A cable suspended in the air on poles or other overhead structure.

A satellite receiver which can be turned to any desired channel.

One in which air is the essential dielectric material. A spirally wound synthetic filament or spacer may be used to center the conductor.

The process of fine tuning a dish or an electronic circuit to maximize its sensitivity and signal receiving capability.

Wiring system which uses two out-of-phase conductors and a common screen to reduce the effect of interference. For balancing to be effective, both the sending and receiving device must have balanced output and input stages respectively.

Wiring system which uses two out-of-phase conductors and a common screen to reduce the effect of interference. For balancing to be effective, both the sending and receiving device must have balanced output and input stages respectively.

Binary coded decimal.

Block Downconverter or Block Downconversion.

Bit Error Rate. Accuracy of digital demodulation or decoding. Analogous to SNR, but in digital transmission.

Software which is not fully tested and may include bugs.

High frequency signal used in analogue recording to improve the accuracy of the recorded signal and to drive the erase head. Bias is generated by a bias oscillator.

Counting system based on only two states - 1s and 0s.

Part of a computer operating system held on ROM rather than on disk. This handles basic routines such as accessing the disk drive.

Binary digit, which may either be 1 or 0.Smallest possible unit of digital transmission.

A weatherproof twist lock coax connector standard on commercial video equipment and used on some brands of satellite receivers.

Backoff (of non-linear system, from saturation). In a satellite transponder, may be qualified as input backoff or output backoff.

Beginning of Life (of a transponder or satellite).

The process of mixing two or more recorded tracks together and re-recording these onto another track.

Band-Pass Filter.

Beats Per Minute.

Binary Phase - Shift keying.

Baseband Processor Unit.

Device that converts breath pressure into MIDI controller data.

Broadcasting Satellite

Circuit designed to isolate the output of a source device from loading effects due to the input impedance of the destination device.

Temporary RAM memory used in some computer operations, sometimes to prevent a break in the data stream when the computer is interrupted to perform another task.

Slang term for software fault or equipment design problem.

A common electrical signal path along which signals may travel. In a mixer, there are several busses carrying the stereo mix, the groups, the PFL signal, the aux sends and so on. Power supplies are also fed along busses.

The matching of the resistive values of the input and output of electronic devices to reduce signal reflection and ghosting. Also known as impedance matching.

That portion of the horizontal blanking pulse that follows the trailing edge of the horizontal sync pulse.

A dual reflector feed system of undefined geometry.

A terrestrial link connecting an earth station to its local switching center or population center.

A unit for designating a specific frequency or range of frequencies in the electromagnetic spectrum.

A device that splits a group of specified frequencies into two or more bands. Common types include UHF/VHF, Hi/Lo band and FM separators. This device is essentially a set of filters.

A circuit or device that allows only a specified range of frequencies to pass from input to output.Frequencies within the band are emphasised.

The range of frequencies occupied by a signal, or passed by a transmission channel. Services requiring a bandwidth greater than 20 kHz, such as TV transmissions, are known as "broadband". Those requiring less capacity, such as audio transmissions, are known as "narrowband".

The band of frequencies containing the information, prior to modulation (and after demodulation).

Unit of data transmission rate, based on the number of signal elements or symbols transmitted per second.

Low-power carrier generated by an auxiliary transmitter. May be unmodulated for propagation tests or tracking, or modulated with telemetry or tracking data

The capability of satellites to shift their beam rapidly - in a matter of milliseconds - so that data can be sequentially processed from multiple earth stations.

The acceptance angle of an antenna, usually measured between half-power (3 dB) points.

One circuit that can be divided by circuit multiplication equipment to carry more than one derived circuit.

Jargon or nick name for communication satellites.

Speed of digital transmission, measured in bits per second (bits/s or b/s), or multiples of thousands or millions (Kbits/s or kb/s; Mbits/s or Mb/s).

The level of composite vidoe signal that seperates the spectra containing video information from the spectra containing synchronizing information.

The reference level for video signals which occurs between succeeding picture frames. The blanking interval contains synchronizing information, and in some cases, teletext signals.

Pulses used to extinguish the scan illumination during horizontal and vertical retrace periods.

The use of fixed-frequency first local oscillator, to downconvert an entire satellite band to a lower intermediate frequency for subsequent tuning and demodulation.

The direction along the principle axis of either a transmitter or a digital antenna.

A set top converter which replaces the television's tuner thus expanding the television set's channel tuning capability.

A fiberous or metallic group of filaments interwoven in cylindrical form to form a covering over one or two wires.

The smaller of the two angles formed by the shielding strand and the axis of the cable being shielded.

A spool or bobbin on a braider which holds one group of strands or filaments consisting of a specific number of ends. The carrier revolves during braiding operations.

The number of strands used to make up one carrier. The strands are wound side by side on the carrier bobbin and lie parallel to the finished braid.

The voltage at which the insulation between two conductors breaks down.

A device that processes a signal(s) spanning a relatively broad range of input frequencies.

A signal transmitted to all user terminals in a service area, or the process.

A group of wires of the same diameter twisted together without a predetermined pattern.

A cable installed directly in the earth without use of underground conduit. Also called "direct burial cable".

A rod shaped like a question mark supporting the feedhorn and LNA. A buttonhook feed for use with commercial grade antennas is often a hollow waveguide that directs signals from a feedhorn to an LNA behind the antenna.

A digital "word," usually consisting of eight bits.

Abbreviation for Bits per second.

Used loosely for satellite downlinks within the 3.4 to 4.2 GHz frequency range.

Carrier-to-interference ratio.

Carrier/Noise Density, i.e., CNR per unit bandwidth.

Carrier-to-noise-Temperature ratio.

Electrical component exhibiting capacitance.

Microphone that operates on the principle of measuring the change in electrical charge across a capacitor where one of the electrodes is a thin conductive membrane that flexes in response to sound pressure.

Meaning heart shaped, describes the polar response of a unidirectional microphone.

An abbreviation for Community Antenna Television - another name for Cable TV.

"C-band Direct" (broadcast). Proposed name for a formalized home TVRO system in the US.

Charge coupled device. In this device charge is stored on a capacitor which are etched onto a chip. A number of samples can be simultaneously stored. Used in MAC transmissions for temporarily storing video signals.

Co-Channel Interference.

International Radio Consultative Committee.

A recordable type of Compact Disc that can only be recorded once - it cannot be erased and reused.

A device capable of recording data onto blank CD-R discs.

Code Division Multiple Access.

In the context of mixing consoles, a channel is a single strip of controls relating to one input.
Or A segment of band width used for one complete communication link.

The process whereby a slave device attempts to synchronise itself with a master device.

Integrated circuit.

Three or more different musical notes played at the same time.

Effect created by doubling a signal and adding delay and pitch modulation.

A scale of pitches rising in semitone steps.

Metronome pulse which assists musicians in playing in time.

Severe form of distortion which occurs when a signal attempts to exceed the maximum level which a piece of equipment can handle.

Exact duplicate. Often refers to digital copies of digital tapes.

A measure of how well a balanced circuit rejects a signal that is common to both inputs.

Encode decode device that compresses a signal while encoding it, then expands it when decoding it.

Device designed to reduce the dynamic range of audio signals by reducing the level of high signals or by increasing the level of low signals.

A device for the storing and processing of digital data.

Material that provides a low resistance path for electrical current.

Alternative term for mixer.

Compound designed to increase the electrical conductivity of electrical contacts such as plugs, sockets and edge connectors.

Type of MIDI message used to translate continuous change, such as from a pedal, wheel or breath control device.

Method used by software manufacturers to prevent unauthorised copying.

Slang term relating to malfunction of computer program.

The ability to copy or move sections of a recording to new locations.

The frequency above or below which attenuation begins in a filter circuit.

Control Voltage, used to control the pitch of an oscillator or filter frequency in an analogue synthesizer.

One complete vibration of a sound source or its electrical equivalent. One cycle per second is expressed as 1Hertz (Hz).

An insulated conductor, or group of individually insulated conductors in twisted or parallel configuration.

A completed cable and its associated hardware ready to install.

Cable Drop or drop cable is that portion of a cable system that connects individual customers to the cable system. The drop begins at a connection point on the cable tap and ends at the customer's television.

A system that transmits original programming, and programming of broadcast television stations, to consumers over a wired network, whether strung across poles overhead or laid underground.

Indian lingo for cable operator.

Used in the formula for calculating the diameter of an unshielded, unjacketed cable. D = Kd. where "D" is the diameter, "K" is the factor and "d" is the diameter of one insulated conductor.

The ratio of the electrostatic charge on a conductor to the potential difference between the conductors required to maintain that charge.

A pure-frequency signal that is modulated to carry information. In the process of modulation it is spread out over a wider band. The carrier frequency is the center frequency on any television channel.

The ratio of the received carrier power to the noise power in a given bandwidth expressed in decibels.

Dual-refiector antenna geometry using a convex hyperboloidal subreflector and paraboloid main reflector.

An antenna feed design that includes a primary reflector, the dish, and a secondary reflector which redirects microwaves via a waveguide to a low noise amplifier.

The impedance that, when connected to the output terminals of a transmission line of any length, makes the line appear infinitely long. The ratio of voltage to current at every point along a transmission line on which there are no standing waves.

The hue and saturation of a color. The chrominance signal is modulated onto a 4.43 MHz carrier in the PAL television system and a 3.58 MHz carrier in the NTSC television system.

The color component of the composite baseband video signal assembled from the I and Q portions. Phase angle of the signal represents hue and amplitude represents colour saturation.

A two-way communications link, most commonly used for sending and receiving voice and data information. Satellite capacity is most often stated in the number of circuits that a satellite can carry.

The area of a circle one mil (.001") in diameter, 7.854 x 10-7 Used in expressing wire cross sectional area.

Electromagnetic waves whose electric field uniformly rotates along the signal path.

A method of applying a layer of metal over another metal whereby the junction of the two metals is continuously welded.

A video procession circuit that removes low-frequency disturbances (e.g. energy dispersal) from the waveform

Of the same polarization.

Cable with several common axis lines under protective sheath used for television signal transmissions.

A transmission system that superimposes the audio or data information onto a specific coded address waveform.

Coder/Decoder system for digital transmission.

Ability of multiple satellites to share the same approximate geostation orbital assignment.

A test pattern of specifically colored vertical bars used as a reference to test the performance of a color television

A system for circuit identification through use of solid colors and contrasting tracers.

A subcarrier which is added to the main video signal to convey the color information.

A synchronizing signal contained within the composite video waveform which serves as a frequency and phase reference for the chrominance information.

A company providing telecommunications services to users under rates and regulations set by the Federal Communications Commission.

A noise-reduction technique involving compression applied at the transmitter, with complementary expansion at the receiver.

The raw demodulator output, prior to filtering and clamping and (usually) prior to de-emphasis. Contains all transmitted subcarriers. In some receivers this output is not intended for video use, and a roll-off may be applied to the lowest baseband frequencies.

Ambiguous term, variously used to refer to composite baseband or composite video.

Complete video signal including synchronizing, luminance and color information, with teletex where transmitted. Does not include audio or data subcarriers.

A central wire surrounded by one or more layers of helical wound strands in a fixed geometric arrangement.

In a wire or cable, the measurement of the location of the center of the conductor with respect to the geometric center of he surrounding insulation.

The capability of a material to carry electrical current - usually expressed as a percentage of copper conductivity (copper being 100%).

A tube or trough in which insulated wires and cables are run.

A complex type of autotracking system.

A device used to physically and electrically connect two or more conductors.

A test to determine whether electrical current flows continuously throughout the length of a single wire or individual wires in a cable.

The ratio between the dark and light areas of a television picture.

A compound resulting from the polymerization of two different monomers.

The trade name of Flexo Wire Division (Copperweld Steel Corp.) for their copper clad steel conductors.

In cables, a component or assembly of components over which additional components (shield, sheath, etc.) are applied.

The percent of completeness with which a metal braid covers the underlying surface.

The minute cracks on the surface of plastic materials.

A form of interference caused by the modulation of one carrier affecting that of another signal. It can be by overloading an amplifier as well as by Signal imbalances at the headened.

Term to describe signals of the opposite polarity to another being transmitted and received. Cross-polarization discrimination refers to the ability of a feed to detect one polarity and reject the signals having the opposite sense of polarity.

Link or cable connection between antenna and equipment building.

Interference between adjacent channels often caused by cross modulation. Leakage can occur between two wires, PCB tracks or parallel cables.

The ability of a material to withstand mechanical pressure, usually a sharp edge or small radius, without separation.

Digital-Analog (Conversion).

Digital to Analog Conversion. Recovery of original analog signal from digital data.

Term used to describe serial electrical connection between devices or modules.

Demand-Assigned Multiple-Access. A spectrum-efficient method of dynamically allocating telephony channels in a transponder.

In the context of reverberation, damping refers to the rate at which the reverberant energy is absorbed by the various surfaces in the environment.

Double Amplitude Peak. Peak-to-Peak measurement (especially of a composite video signal)

Digital Audio Tape. The commonly used DAT machines are more correctly known as R-DAT because they use a rotating head similar to a video recorder. Digital recorders using fixed or stationary heads (such as DCC) are known as S-DAT machines.

Information stored and used by a computer.

A system used to reduce the amount of data needed to represent an audio signal, usually by discarding audio information that is being masked by more prominent sounds.

Direct Broadcasting (by) Satellite to individual homes.

Direct broadcast satellite or direct to home television services. A form of broadcasting wherein high-powered satellites are used to broadcast a bouquet of channels directly to the homes of television viewers.

Direct Current.

Stationary head digital recorder format developed by Philips. Uses a data compression system to reduce the amount of data that needs to be stored.

Digitally Controlled Oscillator.

Digital Delay Line.

Device for reducing the effect of sibilance in vocal signals.

The progressive reduction in amplitude of a sound or electrical signal over time.

The process of rearranging the files on a hard disk so that all the files are as contiguous as possible, and that the remaining free space is also contiguous.

Substance formulated to remove oxides from electrical contacts.

Physical click stop in the centre of a control such as a pan or EQ cut/boost knob.

Short for Direct Inject, where a signal is plugged directly into an audio chain without the aid of a microphone.

Device for matching the signal level impedance of a source to a tape machine or mixer input.

Digital processor for generating delay and echo effects.

Digital processor for simulating reverberation.

Consumer multipin signal connection format, also used for MIDI cabling. Various pin configurations are available.

A means of connecting two electrical circuits so that both AC and DC signals may be passed between them.

Used to describe vinyl discs, CDs and MiniDiscs.

Abbreviation of Diskette, but now used to describe computer floppy, hard and removable disks.

A system of adding low level noise to a digitized audio signal in such a way as to extend to the low level resolution at the expense of a slight deterioration in noise performance.

Direct Memory Access:Part of a computer operating system that allows peripheral devices to communicate directly with the computer memory without going via the central processor or CPU.

An encode/decode tape noise reduction system that amplifies low level, high frequency signals during recording, then reverses this process during playback. There are several different Dolby systems in use: types B, C and S for domestic and semi-professional machines, and types A and SR for professional machines.

Disk Operating System. Part of the operating system of PC and PC compatible computers

Differential Pulse - Code Modulation

Differential Phase - Shift Keying

Piece of software that handles communications between the main program and a hardware peripheral, such as a soundcard, printer or scanner.

Dielectric - Resonator (or Dielectrically-Stabilized) Oscillator. Highly stable oscillator circuit used in LNBs and BDCS.

Synthetic playing surface which produces electronic trigger signals in response to being hit with drum sticks.

A signal that has had no effects added.

Digital Speech Interpolation. A spectrum efficient mode for telephony transmission that take advant of the pauses that occur in conversations to insert additional signals for transmission.

Digital Signal Processor. A powerful microchip used to process digital signals.

Adding further material to an existing recording. Also known as overdubbing.

A system for controlling the level of one audio signal with another.

To transfer digital data from one device to another.

A type of microphone that works on the electric generator principle, where a diaphragm moves a coil of wire within a magnetic field.

The range in dB between the highest signal that can be handled by a piece of equipment and the level at which small signals disappear into the noise floor.

Way of describing the relative levels within a piece of music.

A reduction of the higher frequency portions of an FM signal used to neutralize the effects of pre-emphasis. When combined with the correct level of pre-emphasis, it reduces over-all noise levels and therefore increases the signal-to-noise ratio.

A unit to express differences of power level. Used to express power gain in amplifiers or power loss in passive circuits or cables.

The offset angle of an antenna from the axis of its polar mount as measured in the meridian plane between the equatorial plane and the antenna main beam.

The adjustment angle of a polar mount between the polar axis and the plane of a satellite antenna used to aim at the geosynchronous arc. Declination increases from zero with latitude away from the equator.

A circuit that restores a signal to its original form after it has been scrambled.

The extent by which SNR (or Eb/No) exceeds a value giving an unacceptable BER. (Also Eye Height)

The time it takes for a signal to go from the sending station to the receiving station.

Digital coding system based on the transmission of a change in value, rather than the absolute value of a sample. Exhibits a softer threshold than PCM.

The recovery of baseband information from a modulated carrier.

A device which extracts the baseband signal from the transmitted carrier wave.

The created circuits derived from the bearer circuit. The number of actual voice circuits being carried.

Tuning into a satellite channel by selecting a present resistance.

The level of modulation of an FM signal - the extent by which the baseband or subCarrier signal shifts the main carrier frequency.

Any insulating material between two conductors which permits electrostatic attraction and repulsion to take place across it.

The ratio of the capacitance of a condenser with dielectric between the electrodes to the capacitance when air is between the electrodes. Also called Permittivity and Specific Inductive Capacity.

The voltage which an insulation can withstand before breakdown occurs. Usually expressed as a voltage gradient (such as volts per mil).

Video (color) non-linear distortion parameters.

Electronic system which represents data and signals in the form of codes 
comprising 1s and 0s.

A circuit that converts digital signals into their equivalent analog form.

Conversion of information into bits of data for transmission through wire, fiber optic cable, satellite, or over air techniques. Method allows simultaneous transmission of voice, data or video. Data is represented by a specific sequence of off-on electrical pulses.

A term commonly used to describe Ku-band broadcasts via satellite directly to individual end-users. The DBS band ranges from 11.7 to 12.2 GHz.

The resistance offered by any circuit to the flow of direct current.

Measure of the ability of a component or system to separate wanted from unwanted signals, using some parameter such as polarization.

Type of FM demodulator.

Jargon for a parabolic microwave antenna.

The effect of group delay of a wideband transmission channel changing with frequency, such that different time delays are imparted to components of different frequencies. Most notice able with pulse signals. Not to be confused with Dispersal.

The tangent of the loss angle of the insulating material. (Also referred to as loss tangent, tan &, and approximate power factor).

A communication system consisting of coax but occasionally of line-of-sight microwave links that carriers signals from the headened to end-users.

Abbreviation for domestic communication satellite.

Translation of frequency or a block of frequencies to a lower portion of the electromagnetic spectrum, e.g. from SHF (microwavwe) frequencies to UHF or VHF.

A circuit that lowers the high frequency signal to a lower, intermediate range. There are three distinct types of down conversion used in satellite receivers: single down conversion; dual down conversion; and block down conversion.

The space-to-Earth half of a two-way telecommunications satellite link.

The antenna onboard a satellite which relays signals back to earth.

In a cable, the uninsulated wire laid over the component or components and sued a ground connection.

An instability in a present voltage, frequency or other electronic circuit parameter.

A freedhorn which can simultaneously receive two different bands, typically the C and Ku-bands.

deciBel. Unit used to express the relative levels of two electrical voltages, powers or sounds.
Used to express power gain in amplifiers or power loss in passive circuits or cables.

A means of measuring the slope of a filter. The more dBs per octave, the sharper the filter slope.

dB power relative to one milliwatt.

The ratio of the power to one Watt expressed in decibels.

dB antenna gain relative to an isotropic source.

Variation on DB referenced to 0DB = 1mW into 600Ohms.

Variation on dB referenced to 0dB = 0.775 volts.

A commercial encode/decode tape noise reduction system that compresses the signal during recording and expands it by an identical amount on playback.

A device which stops the flow of dc power but per- rnits passage of higher frequency ac signals.

(Erasable Programmable Read Only Memory) Similar to ROM, but the information on the chip can be erased and replaced using special equipment.

The first sound reflections from walls, floors and ceilings following a sound created In an acoustically reflective environment.

Energy Dispersal.

Device for treating an audio signal in order to change it in some creative way.
Effects often involve the use of delay circuits, and include such treatments as reverb and echo.

Connection system that allows an external signal processor to be connected into the audio chain.

Additional mixer input designed to accommodate the output from an effects unit.

Equivalent Isotropically Radiated Power (or Effective Isotropic Radiated Power). Combined result of transmitter (or transponder) RF power, and transmitting antenna gain.

ype of capacitor microphone utilising a permanently charged capsule.

Abbreviation for electromagnetic interference.

A device designed to brighten audio material using techniques such as dynamic equalisation, phase shifting and harmonic generation.

The way in which the level of a sound or signal varies over time.

A circuit capable of generating a control signal which represents the envelope of the sound you want to recreate. This may then be used to control the level of an oscillator or other sound source, though envelopes may also be used to control filter or modulation settings. The most common example is the ADSR generator.

End of Life (of a transponder or satellite)

Device for selectively cutting or boosting selected parts of the audio spectrum.

To remove recorded material from an analogue tape, or to remove digital data from any form of storage media.

In MIDI terms, an event is a single unit of MIDI data, such as a note being turned on or off, a piece of controller information, a program change, and so on.

An enhancer that works by synthesizing new high frequency harmonics.

A devise designed to decrease the level of low level signals and increase the level of high level signals, thus increasing the dynamic range of the signal.

Synthesizer with no keyboard, often rack mountable or in some other compact 

A complete satellite receiving or transmitting station including the antenna, electronics and all associated equipment necessary to receive or transmit satellite signals. Also known as a ground station.

Energy-per-Bit-to-Noise-Power-density ratio. The digital equivalent of C/No.

Link concentricity, a measure of the center of a conductor's location with respect to the circular cross section of the insulation. Expressed as a percentage of displacement of one circle within the other.

A time delayed electronic reflection of one's voice caused by an electrical discontinuity in telephone circuit. Echoes are often experienced during satellite-delivered long distance telephone calls.

An electronic circuit which attenuates or eliminates the echo effect on satellite telephone links.

Period when the satellite passes into the Earth's or the Moon's shadow, when power must be drawn from storage batteries.

Refers to a transponder that can remain powered during the period of an eclipse.

Limit of defined service area, typically 3 dB down from beam center, but may be more. Reception is still possible beyond this line.

A measure of the signal strength that a satellite transmits towards the earth below. The EIRP is highest at the center of the beam and decreases at angles away from the boresight.

Soviet UHF DBS satellite serving the Statsionar - T system. Downlinks at 714 MHz Siberia, but has usable coverage throughout Asia. Located 99 degrees E.

An antenna mount providing independent steering in Azimuth and Elevation.

The entire range of wavelengths of electromagnetic radiation - including visible light - which extend from gamma rays to microwaves and radio waves, all of which travel at the speed of light (186,000 miles per second or 300,000,000 meters per second).

Angle between antenna beam and horizontal plane (measured in vertical plane).

The fractional increase in length of a material stressed in tension.

A device used to electronically alter a signal so that it can only be viewed on a receiver equipped with a special decoder.

A satellite TV receiving antenna component that collects the signal reflected from the main surface reflector and channels this signal into the low-noise amplifier (LNA).

In braiding, the number of essentially parallel wires or threads on a carrier.

A low-frequency waveform added to the baseband signal before modulation to reduce the FM signal's peak power per unit band-width, and thus reducing its interference potential.

A series of six pulses occurring before and after the serrated vertical sync pulse to ensure proper interlacing. The equalizing pulses are inserted at twice the horizontal scanning frequency.

Astronomers' term for Polar Mount.

An orbit with a plane that is parallel to the Arth's equator.

The modulator and driver section of a transmitter, as used in an uplink.

A measurement of SNR on a digital bitstream.

A standard RF connector used to link coax cables with electronic devices.

Sliding potentiometer control used in mixers and other processors.

Frequency Division Multiplex

Frequency Division Multiple Access

Forward Error Correction. Coding technique used in digital transmission.

Type of magnetic tape coating that uses iron oxide.

Field Effect Transistor.

Field-Effect Transister. Semiconductor device used in LNAS, LNBS, and LNCS. See also GaAs.

Describes the polar response of a microphone that is equally sensitive both front and rear, yet rejects sounds coming from the sides.

A meaningful list of data stored in digital form.

An electronic circuit designed to emphasize or attenuate a specific range of frequencies.

Modulated delay effect using feedback to create a dramatic, sweeping sound.

Computer disk that uses a flexible magnetic medium encased in a protective plastic sleeve. The maximum capacity of a standard High Density disk is 1.44Mbytes.

Resonant echo that occurs when sound reflects back and forth between two parallel, reflective surfaces.

Frequency modulation. A modulation method whereby the baseband signal varies the frequency of the carrier wave. Also referring to audio service broadcast over 88 MHz-108 MHz.

Frequency Modulation Feedback, a technique for deviation reduction and threshold extension.

System for feeding one or more separate mixes to the performers for use while recording and overdubbing. Also known as a Cue mix.

Frequency component or resonance of an instrument or voice sound that doesn't change with the pitch of the note being played or sung.

Procedure required to ready a computer disk for use. Formatting organises the disk's surface into a series of electronic pigeon holes into which data can be stored. Different computers often use different formatting systems.

The process by which the available space on a disk drive gets split up into small sectionsdue to the storing and erasing of files.

Indication of how many cycles of a repetitive waveform occur in 1 second. A waveform which has a repetition cycle of once per second has a frequency of 1Hz (pronounced Hertz).

A measurement of the frequency range that can be handled by a specific piece of electrical equipment or loudspeaker.

Frequency Shift Keying. A method of recording a sync clock signal onto tape by representing it as two alternating tones.

Fixed-Satellite Service.

Any sound comprises a fundamental or basic frequency plus harmonics and partials at a higher frequency.


When peak sunspot activity highly charges the Earth's ionosphere, the vectors of linearly-polarized satellite signals can be rotated or "twisted" through interaction with the Earth's atmosphere.

Co-axial cable transmission line connecting outdoor and indoor units.

A satellite TV receiving antenna component that collects the signal reflected from the main surface reflector and channels this signal into the low-noise amplifier (LNA).

Wires made of glass fiber used to transmit video, audio, voice or data providing vastly wider bandwidth than standard coaxial cable.

One half of a complete TV picture or frame, composed of 262.5 scanning lines. There are 60 fields per second for black/white TV and 59.94 fields per second for colour TV in NTSC transmission. In the PAL broadcast system there are 50 fields per second.

An aerial cable configuration in which the conductors and the steel strand which supports the cable are integrally jacketed. A cross section of the finished cable approximates the figure "eight".

The ability of a material not to propagate flame once the heat source is removed.

The measurement of the ability of a conductor or cable to withstand repeated bending.

The distance from the reflective surface of a parabola to the point at which incoming satellite signals are focused, the local point.

The portion of the earth's surface covered by the signal from a communications satellite.

FEC is a technique for improving the accuracy of data transmission. Excess bits are included in the outgoing data stream so that error correction algorithms can be applied upon reception.

One complete TV picture, composed of two fields and a total of 525 and 625 scanning lines in NTSC and PAL systems, respectively.

A technique which maximizes the capacity of a telecommunications satellite through the use of spatially-isolated beam antennas andlor the use of dual polarities.

The portion of the horizontal blanking pulse that precedes the horizontal sync pulse.

The ratio of an antenna's focal length to diameter. It describes antenna "depth".

Gain-to-noise-Temperature ration of a receiving system; its sensitivity "Figure of Merit".

The amount by which a circuit amplifies a signal.

An electronic device designed to mute low level signals so as to improve noise performance during pauses in the wanted material.

The Geosynchronous Equatorial (Ciarke) Orbit. Unique orbit in which a body can remain essentially stationary relative to Earth coordinates.

Unit of frequency equal to 1000 MHz, one billion (10 °) cycles per second.

Gain-to-noise-Temperature ratio of receiving system; its sensitivity or "figure of merit". The higher the GIT better the reception capability of earth station.

Describes an unwanted short term corruption of a signal, or the unexplained, short term malfunction of a piece of equipment.

Greenwich Mean Time. The international universal standard time.

An equaliser whereby several narrow segments of the audio spectrum are controlled by individual cur/boost faders. The name comes about because the fader positions provide a graphic representation of the EQ curve.

Wiring problem where multiple ground connections are causing audible mains hum to be picked up. Also known as earth loops.

A collection of signals within a mixer that are mixed, then routed through a separate fader to provide overall control. In a multitrack mixer, several groups are provided to feed the various recorder track inputs.

Geostationary (Geosynchronous) Transfer Orbit.

Gallium Arsenide. High-mobility semicoductor material used in low-noise microwave devices.

The amount of amplification of input to output power often expressed as a multiplicative factor or in decibels.

A network accesspoint. An interchange between two networks, for instance between national and international telecommunications networks (INTELSAT Gateway).

A term used to denote the physical size of a wire.

Prograde orbit having a period equal to that of the Earth's rotation (need not imply geostationary).

The orbit directly above the equator, about 35,800 kilometers (22,300 miles) above the earth in space. Also known as GEO, geostationary and Clarke orbit. When positioned in this orbit, a satellite appears to hover over the same spot on the earth because it is moving at a rate that matches the speed of the earth's rotation on its axis.

A numerical prefix denoting one billion (10 °).

Beam covering the entire visible Earth surface, (42 percent of the globe) as seen from the satellite.

Russian FSS satellites serving the STATSIONAR system in the C- and Ku-bands.

Russian FSS satellites serving the STATSIONAR system in the C- and Ku-bands.

Dual-reflector antenna geometry using a concave ellipsoidal subreflector and paraboloidal main reflector.

Unwanted microwave signals generated from the warm ground and detected by a dish.

A signal distortion parameter.

An unused spectra of frequencies which lie above and below each transponder. The guard band helps to prevent adjacent communications signals from interfering with one another.

Homestead and community Broadcasting Satellite Service. Remote area DBS service via AUSSAT.

High capacity computer storage device based on a rotating rigid disk with a magnetic coating onto which data may be recorded.

High frequency component of a complex waveform.

The addition of harmonics that were not present in the original signal.

High-definition television.

The part of a tape machine or disk drive that reads and/or writes data to and from the storage media.

The safety margin in dBs between the highest peak signal being passed by a piece of equipment and the absolute maximum level the equipment can handle.

High Electron Mobility Transistor.

A filter which attenuates frequencies below its cutoff frequency.

Noise caused by random electrical fluctuations.

High-Power amplifier (esp. in an upline). Usually a TWTA or a Klystron.

High-Pass Filter.

Signal contamination caused by the addition of low frequencies, usually related to the mains power frequency.

A method of transmitting two TV signals through a single transponder, by reducing the deviation and power allocated to each. TV carriers each operate typically 4 dB to 7 dB below single-carrier saturation power.

The uplink and downlink between the same earth station and a sattle.

A semiconductor device in which an output voltage is generated in response to the intensity of a magnetic field applied to a wire. In an actuator, the varying magnetic field is produced by the rotation of a permanent magnet past a thin wire. The pulses generated serve to count the number of rotations of the motor.

Copper wire that has not been annealed after drawing.

A low-loss coaxial cable that has a continuous had metal shield instead of a conductive braid around the outer perimeter. This type of cable was used in the pioneer days of satellite television.

Alternative term for an LNA, LNB, or LNC. Also called the outdoor unit.

Central distribution point for a CATV or MATV system.

A thick low-loss cable used at high frequencies; also known as hard-line.

Shaped beam covering approximately half of the visible Earth's surface (21 percent of the total globe), as seen from the satellite.

The name given to the basic measure of radio frequency. 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 single Hertz is thus equal to one cycle per second.

A term designed to determine the highest voltage that can be applied to a conductor without breaking through the insulation.

An innovative television format having approximately twice the number of scan lines in order to improve picture resolution and viewing quality.

An amplifier used to amplify the uplink signal

Satellite with transponder RF power in excess of about 100 watts.

The pulse that occurs between each horizontal scan line and existinguishes the beam illumination during the retrace period.

A 5.08 microsecond (4.7 microsecond in the PAL system) rectangular pulse riding on to of each horizontal blanking pulse. It synchronizes the horzontal scanning at the television set with that of the television camera.

Angle between antenna beam and meridian plane (measured in equatorial plane). Steering direction of a polar mount antenna.

Spectral tint parameter in a color video signal.

A form of interference seen as horizontal bars or black regions passing across the field of a television screen.

Dupont's trade name for their chlorosuifonated polyethylene, an ozone resistant synthetic rubber.

Short for Hertz, the unit of frequency.

One of the two color video signals which modulate the color subcarrier. It represents those colors ranging from reddish orange or cyan.

The part of a system that handles inputs and outputs, usually in the digital domain.

Integrated Circuit.

International Digital Route. The digital equivalent of the analog FDM/FM voice service used by INTELSAT.

Tracking and Data-Relay Satellite (System) used by NASA.

Intermediate Frequency. A middle range frequency generated after down conversion in any electronic circuitry including a satellite receiver. The majority of all signal amplification, processing and filtering in a receiver occur in the IF range.

Inter-Facility Link. Anything from a cross-site transmission line to a complete data network.

lnterrnodulation Distortion (in nonlinear system).

Reactive component that presents an increasing impedance with frequency.

To automatically restore a piece of equipment to its factory default settings.

Indian National Satellite System.

A connector that allows an external processor to be patched into a signal path so that the signal now flows through the external processor.

Material that does not conduct electricity.

The International Telecommunication Satellite Consortium, a body of 154 countries working towards a common gol of improved worldwide satellite communications.

A device that acts as an intermediary to two or more other pieces of equipment.

Usually describes a fault that only appears occasionally.

A form of distortion that introduces frequencies not present in the original signal. These are invariably based on the sum and difference products of the original frequencies.

Intermediate Power Amplifier (Uplink Transmitter).

Inches Per Second. Used to describe tape speed.

Interrupt Request. Part of the operating system of a computer that allows a connected device to request attention from the processor in order to transfer data to it or from it.

Integrated Services Digital Network. A high quality global telecommunications network based on digital technology. ISDN is designed to allow subscribers to access a multiplicity of communications services through a single point or connector in the network.

Type of alcohol commonly used for cleaning and de-greasing tape machine heads and guides.

Insertion Test Signal (also VITS) for monitoring a channel's video performance parameters.

Internal Upper Stage (for GEO launches) A type of PKM. are scanned in separate fields both of which when combined paint one frame or complete picture.

The total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency. It is a combination of resistance R and reactance X, measured in ohms.

Impulse pay-per-view (IPPV) is a feature of a decoder that allows an authorized subscriber to purchase a non-time scrambled program at will. IPPV shows are selected by a button on the decoder or its remote control unit.

Angle between orbital plane of satellite and equatorial plane of the Earth.

An instrument used to measure the angle of elevation to a satellite from the surface of the earth.

The property of a circuit or circuit element that opposes a change in current flow, thus causing current changes to Jag behind voltage changes. It is measured in henrys.

Low-cost technique for phase-locking a cavity or resonator oscillator to a crystal source, to improve its frequency stability.

The amount of signal energy lost when a device is inserted into a communication line. Also known as "feed through" loss.

A material having high resistance to the flow of electric current. Often called a dielectric in radio frequency cable.

The ratio of the applied voltage to the total current between two electrodes in contact with a specific insulation, usually expressed in megohms - M feet.

An undesired signal intercepted by a TVRO that causes video and/or audio distortion.

Antenna feed generating controlled pattern of sidelobes and nulls, to permit use of small antennas with closely satellites.

A scanning technique to minimize picture flicker while conserving channel bandwidth. Even and odd numbered lines are scanned in separate fields both of which when combined paint one frame or complete picture.

A transmission path directly between two communications satellites.

The measure of separation (as dB or power ratio) between two potentially interfering signals, e.g. in difference beams or on different polarizations.

The amount of signal energy lost between two ports of a device. An example is the loss between the feed through port and the tap/drop of a top-off device.

Transmission-line component which passes signals with low loss in a preferred direction, while presenting high attenuation in the reverse direction.

Reference for antenna gain measurements.

Prime focus feed system with rear flange connected via hook-shaped waveguide run.

Commonly used audio connector. May be mono or stereo.

Specialised words associated with a specialist subject.

An outer non-metallic protective covering applied over an insulated wire or cable.

The frequency spectrum 10.9 to 36 GHz.

Kilohertz. One thousand hertz (cycles) per second.

Used loosely for 30/20 GHz satellite systems.

The temperature above absolute zero, the temperature at which all molecular motion stops, graduated in units the same size as degrees Celsius (OC). Absolute zero equals -273° C or -459° F.

A numerical prefix denoting 1000 (10° ).

One thousand cycles per second.

Type of high-power beam tube used in some HPAS.

Abbreviation for 1000 (kilo). Used as a prefix to other values to indicate magnitude.


1000 ohms

The frequency range from 0.5 to 1.5 GHz. Also used to refer to the 950 to 1450MHz used for mobile communications.

Liquid Crystal Display.

Proposed mobile satellite systems using LEO.

Light emitting diode. Type of semiconductor that lights up when activated by voltage.

Light Emitting Diode. A form of solid state lamp.

Low Earth Orbit.

Low Frequency Oscillator, often found in synths or effects using modulation.

Left-Hand Circuir Polarization.

Device that controls the gain of a signal so as to prevent it from ever exceeding a preset level. A limiter is essentially a fast acting compressor with an infinite compression ratio.

A nominal signal level which is around -10dBV for semi-pro equipment and +4dBu for professional equipment.

A device where the output is a direct multiple of the input.

Low-Noise Amplifier.

A combination of a feed, automatic polarizer and low noise amplifier in a common package.

Electrical circuit that draws power from another circuit or power supply. Also describes reading data into a computer.

A function to allow the keyboard and sound generating section of a keyboard synthesizer to be used independently of each other.

Type of electronic circuitry used for processing binary signals comprising two discrete voltage levels.

Circuit where the output is connected back to the input.

Line of Sight.

Loss of Signal.

An oscillator used as a modulation source, usually below 20Hz. The most common LFO waveshape is the sine wave, though there is often a choice of sine, square, triangular and sawtooth waveforms.

A filter which attenuates frequencies above its cutoff frequency.

Low Pass Filter.

Low-power transmitters used to broadcast terestrial signals over a small area.

Least Significant Byte. If a piece of data has to be conveyed as two bytes, one byte represents high value numbers and the other low value numbers, much in the same way as tens and units function in the decimal system. The high value, or most significant part of the message is called the Most Significant Byte or MSB.

An eary resources technology satellite.

The distance, expressed in degrees, from the Earth's equator to points north or south. The equator is assigned a value of 0 degrees; North and South poles are 90 degrees.

The length measured along the axis of a wire or cable required for a single strand (in stranded wire) or conductor (in cable) to make one complete turn about the axis of the conductor or cable.

A dedicated circuit typically supplied by the telephone company.

An amplifier in a transmission line that boosts the strength of a signal.

Type of videoscrambling.

An active or passive device that divides a signal into two or more signals containing all the original information. A passive splitter feeds an attenuated version of the input signal to the output ports. An active splitter amplifiers the inputs signal to overcome the splitter loss.

The calculation of power and noise levels between transmitter and receiver (uplink or downlink), taking account of all gain and loss factors, to yield operating values of CII and C/NR, margin above threshold, and ultimate SINR or BER.

The extent (in dB) by which normal working (or clear sky) C/NR exceeds threshold CINR, or other value at which reception is deemed unusable.

A device used to supply a stable single frequency to an upconverter or a downconverter. The local oscillator signal is mixed with the carrier wave to change its frequency.

The distance in degrees east or west of the prime meridian, located at zero degrees.

A tape shield, flat or corrugated, applied longi- tudinally with the axis of the conductor or cable.

Energy dissipated without accomplishing useful work.

An insulating material that has a relatively low dielectric loss, such as polyethylene or Teflon.

This is the preamplifier between the antenna and the earth station receiver. For maximum effectiveness, it must be located as near the antenna as possible, and is usually attached directly to the antenna receive port. The LNA is especially designed to contribute the least amount of thermal noise to the received signal.

A low noise microwave amplifier and converter which downconverts a block or range of frequencies at once to an intermediate frequency range, typically 950 to 1450 MHz or 950 to 1750 MHz.

An LNA and a conventional box. This device converts one channel at a time. Channel selection is controlled by the satellite receiver. The typical IF for LNCs is 70 MHz.

Satellite with transponder RF power below about 30 watts.

Light and shade information in a video signal.

Mega-, one million or 106 .

Multiplexed Analog Components. An enhanced color TV transmission system developed especially for satellite use. Differences between the various types of MAC have to do with the various types of sound and data channels used.

Way of describing the tuning machines of a guitar.

Master Antenna Television - private cable.

Megabyte. 1,000,000 (one million) bytes of data.

Multiple Beam Tours Antena (Comsat design)

Modular Digital Multitrack; a digital recorder that can be used in multiples to provide a greater number of synchronized tracks than a single machine.

Abbreviation for 1,000,000.

Computer's RAM memory used to store programs and data. This data is lost when the computer is switched off and so must be stored to disk or other suitable media.

List of choices presented by a computer program or a device with a display window.

The low level signal generated by a microphone. This must be amplified many times to increase it to line level.

Specialised microchip at the heart of a computer. It is here that instructions are read and acted upon.

Musical Instrument Digital Interface.

Device that gives a visual readout of MIDI activity when connected between two pieces of MIDI equipment.

A type of controller message used to select alternate banks of MIDI Programs where access to more than 128 programs is required.

Also knows as MIDI Controllers or Controller Data, these messages convey positional information relating to performance controls such as wheels, pedals, switches and other devices. This information can be used to control functions such as vibrato depth, brightness, portamento, effects levels, and many other parameters.

A term used to describe the physical interface by means of which the musician plays the MIDI synthesizer or other sound generator. Examples of controllers are keyboards, drum pads, wind synths and so on.

A standard file format for storing song data recorded on a MIDI sequencer in such as way as to allow it to be read by other makes or model of MIDI sequencer.

A chart, usually found in MIDI product manuals, which provides information as to which MIDI features are supported.

The socket used to receive information from a master controller.

A device or sequencer function that enables two or more streams of MIDI data to be combined.

Sound generating device with no integral keyboard.

Message sent when key is released.

MIDI message sent when note is played (key pressed).

The MIDI connector used to send data from a master device to the MIDI In of a connected slave device.

The socket on a master controller or sequencer used to send MIDI information to the slave units.

The MIDI connections of a MIDI compatible device.

Type of MIDI message used to change sound patches on a remote module or the effects patch on a MIDI effects unit.

Alternative term for MIDI Thru box.

A description of the synchronisation systems available to MIDI users - MIDI Clock and MIDI Time Code.

The socket on a slave unit used to feed the MIDI In socket of the next unit in line.

Device for combining two or more audio signals.

Microwave Multipoint Distribution Service also known as wireless cable.

A reference loudspeaker used for mixing.

A display unit for a computer.

The action of listening to a mix or a specific audio signal.

One note at a time.

The main circuit board within a computer into which all the other components plug or connect.

Multiple cable systems operator - a cable operator owning more than one cable network. MSO examples in India are Siticable, In Cablenet, Hathaway, Asianet.

MIDI Time Code; a MIDI sync implementation based on SMPTE time code.

A synthesizer, sampler or module that can play several parts at the same time, each under the control of a different MIDI channel.

MIDI Sound Source capable of producing several different sounds at the same time and controlled on different MIDI channels.

A recording device capable of recording several 'parallel' parts or tracks which may then be mixed or re-recorded independently.

The difference between true north and the north indication of a compass.

Describes a system operating with nil, or inadequate, signal margin.

Broadcast receiving stations that use one or more high-quality centrally located UHF and/or VHF antennas which relay their signals to many televisions in a local apartment/condo or group-housing complex.

The condition that exists when 100 percent of available power is transmitted from one device to another without any losses due to reflections.

A device used to match impedance between devices. A matching transformer is used, for example, when connecting a 75 ohm coax to a television 300 ohm input terminal.

Satellite with transponder RF power in the region of 3OW to 1OOW.

Satellite with transponder RF power in the region of 30 to 60 watts.

One millions cycles per second.

Lines circling from pole to pole which cross each of the 360 degrees which comprise the Earth's equator.

A numerical prefix denoting one-millionth (106 ).

The central processing unit of a computer or control system, either on a single integrated (IC) circuit chip or on several Ics.

The frequency range from approximately 1 to 30 GHz and above.

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.

A unit used in measuring diameter of a wire or thickness of insulation over a conductor. One one-thousandth of an inch (.001").

A device used to combine signals together.

Modulator/demodulator, Usually applied to a device for converting digital data to audio tones (and vice versa) for transmission via an analog channel.

A process in which a message is added or encoded onto a carrier wave.

The ratio of peak deviation to highest modulating frequency, in an FM system.

Consumer satellite receivers are equipped with a VHF or UHF demodulator to supply a standard AM TV channel to home TV receiver

The ratio of stress to strain in an elastic material.

A black and white television picture.

The basic chemical unit used in building a polymer.

Hardware-based automatic antenna tracking system.

The structure that supports an earth station antenna. Polar and az-el mounts are the most commonly variety.

A video test waveform included ins ITS.

An innovative television transmission method which separate the data, chrominance and luminance components and compresses them for sequential relay over one television scan line.

Techniques that allow a number of simultaneous transmissions over a single circuit.

The simultaneous transmission of two or more signals over a single communication channel.

A single communications line or circuit interconnecting several stations.

Capacitance between two conductors when all the other conductors including ground are connected together and then regarded as an ignored ground.


Mill- on-thousandth or 10-3.

milliamp or one thousandth of an amp

A low-loss coaxial cable connector used at the elevated C-band microwave frequencies.

Some people prefer the term 'close field', to describe a loudspeaker system designed to be used close to the listener. The advantage is that the listener hears more of the direct sound from the speakers and less of the reflected sound from the room.

System for reducing analogue tape noise or for reducing the level of hiss present in a recording.

A system for creating digital dither such that any added noise is shifted into those parts of the audio spectrum where the human ear is least sensitive.

Describes digital recording systems that allow any parts of the recording to be played back in any order with no gaps. Conventional tape is referred to as linear, because the material can only play back in the order in which it was recorded.

A socket is said to be normalised when it is wired such that the original signal path is maintained unless a plug is inserted into the socket. The most common examples of normalised connectors are the insert points on a mixing console.

The National Television Standards Committee which created standard for North american TV Braodcasts

The standard test pattern of six adjacent color bars including the three primary colors pulse their three complementary shades.

Slotted plastic or bone component at the headstock end of a guitar neck used to guide the strings over the fingerboard, and to space the strings above the frets.

A numerical prefix denoting one-billionth (106 ).

Positioning the composite video signal so that the maximum level of the sync pulses is at 100% amplitude. The brightest picture singals are in the opposite negative direction.

Transmission system used in North America and other countries in which a decrease in illumination of the original scene causes an increase in percentage of modulation of the picture carrier. When demodulated, signals with a higher modulation percentage have more positive voitages.

An unwanted signal which interferes with reception of the desired information. Noise is often expressed in degrees Kelvin or in decibels.

Measurement of noise contribution of an amplifier relative to a noise-free amplifier at a reference temperature. Usually expressed in dB for Ku-band amplifiers.

The Noise figure of a theoretical infinite chain of identical amplifiers.

A measure of the amount of thermal noise present in a system or device. The lower the noise temperature,the better the performance.

The imbalance associated with a spinning object.

Out of band noise.

When a frequency or pitch is transposed up by one octave, its frequency is doubled.

Process carried out while a recording is not playing. For example, some computer-based processes have to be carried out off-line as the computer isn't fast enough to carry out the process in real time.

Abbreviation for oxygen-free, high conductivity copper. It has no residual deoxidant, 99.95% minimum copper content and an average annealed conductivity of 101%.

Unit of electrical resistance.

Meaning all, refers to a microphone that is equally sensitive in all directions, or to the MIDI mode where data on all channels is recognised.

Orthogonal-Mode Transducer or otho-coupler; waveguide component that separates or combines othogonally polarized signals.

A break in an electrical circuit that prevents current from flowing.

A tape machine where the tape is wound on spools rather than sealed in a cassette.

The basic software that enables a computer to load and run other programs.

A device where some electrical parameter changes in response to a variation in light intensity.

Circuit designed to generate a periodic electrical waveform.

Orbital Test Satellite. Pre-operational test vehicle for Eurpoean Communcations Satellite.

To add another part to a multitrack recording or to replace one of the existing parts.

To exceed the operating capacity of an electronic or electrical circuit.

The half frame of a television scan which is composed of the odd numbered lines.

An antenna whose reflector forms only part of a paraboloid of revolution, usually excluding the pole or apex, such that a front feed causes no aperture blockage.

A unit of electrical resistance.

Mutually at right angles (e.g., horizontal and vertical polarization, or right-hand left-hand circular polarization).

A waveguide, generally a three-port device, that allows simultaneous reception of vertically and horizontally polarized signals. The input port is typically a circular waveguide. The two output ports are rectangular waveguides.

Phase Alternation System - the German developed TV standard based upon 50 cycles.per second and 625 lines.

Control enabling the user of a mixer to move the signal to any point in the stereo soundstage by varying the relative levels fed to the left and right stereo outputs.

A means of connecting two or more circuits together so that their inputs are connected together, and their outputs are all connected together.

A variable value that affects some aspect of a device's performance.

An equaliser with separate controls for frequency, bandwidth and cut/boost.

A circuit with no active elements.

Alternative term for Program, referring to a single programmed sound within a synthesizer that can be called up using Program Change commands.

A system of panel-mounted connectors used to bring inputs and outputs to a central point from where they can be routed using plug-in patch cords.

Short cable used with patch bays.

Pulse Code Modulation. Coding system for digital audio transmission.

Personal Communications Service.


Maximum instantaneous level of a signal.

The highest signal level in any section of programme material.

Pre Fade Listen; a system used within a mixing console to allow the operator to listen in on a selected signal, regardless of the position of the fader controlling that signal.

48V DC supply for capacitor microphones, transmitted along the signal cores of a balanced mic cable.

The timing difference between two electrical waveforms expressed in degrees where 360 degrees corresponds to a delay of exactly one cycle.

Effect which combines a signal with a phase shifted version of itself to produce creative filtering effects. Most phasers are controlled by means of an LFO.

Hi-Fi connector developed by RCA and used extensively on semi-pro, unbalanced recording equipment.

The part of a guitar that converts the string vibrations to electrical signals.

Musical interpretation of an audio frequency.

"A special control message specifically designed to produce a change in pitch in
response to the movement of a pitch bend wheel or lever. Pitch bend data can be recorded and edited."

Device for changing the pitch of an audio signal without changing it's duration.

Phase Locked Loop (type of demodulator) Pulse width modulation.

Phase modulation

"The most common MIDI mode that allows and instrument to respond to multiple 
simultaneous notes transmitted on a single MIDI channel."

The ability of an instrument to play two or more notes simultaneously. An instrument which can only play one note at a time is described as monophonic.

Connection for the input or output of data.

A gliding effect that allows a sound to change pitch at a gradual rate, rather than abruptly, when a new key is pressed or MIDI note sent.

Work done to a stereo recording after mixing is complete.

Aux signal taken from after the channel fader so that the aux send level follows any channel fader changes. Normally used for feeding effects devices.

A unit designed to convert mains electricity to the voltages necessary to power an electronic circuit or device.

Peak Programme Meter; a meter designed to register signal peaks rather than the average level.

Pulsed Per Quarter Note. Used in the context of MIDI Clock derived sync signals.

Pay-per-view. A system by which a viewer can pay and view the programme he wants from a programming menu.

Process for adding Pause, Cue and other subcode information to a digital 
master tape in preparation for CD manufacture.

A system for applying high frequency boost to a sound before processing so as to 
reduce the effect of noise. A corresponding de-emphasis process is required on playback so as to restore the original signal, and to attenuate any high frequency noise contributed by the recording process.

Aux signal taken from before the channel fader so that the channel fader has no effect on the aux send level. Normally used for creating Foldback or Cue mixes.

Effects unit or synth patch that cannot be altered by the user.

Alternative term for Aftertouch.

The undesirable process that causes some magnetic information from a recorded analogue tape to become imprinted onto an adjacent layer. This can produce low level pre or post echoes.

Device designed to treat an audio signal by changing its dynamics or frequency 
content. Examples of processors include compressors, gates and equalisers.

MIDI message designed to change instrument or effects unit patches.

An abbreviation for polarity selection device.

Phase-shift Keying (type of digital modulation).

Similar to a square wave but non-symmetrical. Pulse waves sound brighter and
thinner than square waves, making them useful in the synthesis of reed instruments. The timbre changes according to the mark/space ratio of the waveform.

"A means of modulating the duty cycle (mark/space ratio) of a pulse wave. This 
changes the timbre of the basic tone; LFO modulation of pulse width can be used to produce a pseudo-chorus effect."

"The action of placing an already recorded track into record at the correct time 
during playback, so that the existing material may be extended or replaced."

"The action of switching a tape machine (or other recording device), out of
record after executing a punch-in. With most multitrack machines, both punching in and punching out can be accomplished without stopping the tape."

An audio transmission format used by the Russians to transmit the TVs signals within the video's horizontal blanking interval.

"Pressure Zone Microphone. A type of boundary microphone. Designed to reject 
out-of-phase sounds reflected from surfaces within the recording environment. "

The transfer of data by means of addressed packets whereby a channel is only occur for the duration of transmission of the packet. The channel is then available for the transfer of other pack.

Resistive circuit for reducing signal level.

A concrete base upon which a supporting pole and antenna can be mounted.

Indonesia / ASEAN regional satellite system.

The geometric shape that has the property of reflecting all signals parallel to its axis to one point, the focal point.

A parabola of revolution. Classical shape of a satellite antenna's reflector.

Parametric Amplifier. Sophisticated type of LNA.

The attenuation that a signal undergoes in travelling over a path between two points. Path loss varies inversely as the square of the distance traveled.

Pay-per-view is a method of purchasing programming one a per-program basis.

Conductivity of a material expressed as a percentage of that of copper.

Lowest point (minimum altitude) of a geocentric orbit.

The uniformly spaced variations in the insulation diameter of a transmission cable that result in reflections of a signal, when its wavelength or a multiple thereof is equal to the distance between two diameter variations.

The physiological phenomena whereby a human eye retains perception of an image for a short time after the image is no longer visible.

A distortion of the phase component of a signal. This occurs when the phase shift of an amplifier is not proportional to frequency over the design bandwidth.

Distance between two adjacent crossover points of braid filaments. The measurement in picks per inch indicates the degree of coverage.

A numerical prefix denoting one-millionth of one-millionth (10 (12)).

The number of picture elements resolved on a television picture screen. More "crisp" pictures result as the number of picture elements is increased.

In flat cable, the nominal distance between the index edges of two adjacent conductors.

Flat satellite antenna composed of a gridwork of tiny resonant elements.

A chemical agent added to plastics to make them softer and more pliable.

A communications line connected directly from one point to one other point as opposed to multipoints lines.

Antenna mechanism permitting steering along the geostationary Arc (Clarke Orbit) by rotation about a single axis. Also Equatorial Mount. A classical polar mount has its axis parallel to that of the Earth. Satellite receiving antennas use modified polar mount geometry, incorporating a declination offset.

An orbital path located along the plane of the Earth's polar axis.

A characteristic of the electromagnetic wave. Four senses of polarization are used in satellite transmissions: horizontal; vertical; right-hand circular; and left-hand circular.

A birefringent component in a waveguide or antenna system, which converts between linear (plane) and circular pofarizations. Not a polarization rotor.

A proprietary name for a type of polarization rotor, a transition with a remotely-rotatble probe.

A material of high molecular weight formed by the chemical union of rnonomers.

Any of the polymers and copolymers of the ethylene family of hydrocarbons.

Positioning of the composite video signal so that the maximum point of the sync pulses is at zero voltage. The brightest illumination is caused by the most positive voitages.

The first amplification stage.

A transponder which is sold or leased under the condition that it can be supplied in an emergency to primary customers which have leased or purchased protected transponders from the selling or leasing entity.

Red, green and blue.

A parabolic dish having the feed/LNA assembly at the focal point directly in the front of the antenna.

Entities which lease or purchase protected transponders are guaranteed acce the supplier to a backup transponder in the event that the primary transponder fails. (Also see preem transponder).

A type of channel noise measurement.

A video test waveform, included in ITS.

Power-flux Density (related to field strength)

A measure of the resonant properties of a filter. The higher the Q, the more resonant the filter and the narrower the range of frequencies that are allowed to pass.

One of two color video signal components used to modulate the color subcarrier. It represents the color range from yellowish to green to magenta.

Quasi-DBS. The use of FSS satellites to provide a broadcasting service.

Quadrature Phase Shift Keying - a system of modulating a satellite signal.

A four conductor cable.

Digital tape machine using a rotating head system.

"Abbreviation for Random Access Memory. This is a type of memory used by 
computers for the temporary storage of programs and data, and all data is lost when the power is turned off. "

An audio process that can be carried out as the signal is being recorded or played back. The opposite is off-line, where the signal is processed in non-real time.

The time taken for a level or gain to return to normal.

The rate at which a signal amplitude decays once a key has been released.

Opposition to the flow of electrical current. Measured in Ohms.

"The accuracy with which an analogue signal is represented by a digitising system. 
The more bits are used, the more accurately the amplitude of each sample can be measured, but there are other elements of converter design that also affect accuracy. High conversion accuracy is known as high resolution."

"The characteristic of a filter that allows it to selectively pass a narrow range of frequencies."

Acoustic ambience created by multiple reflections in a confined space.

Radio Frequency.

Interference significantly above the range of human hearing.

Red, Green, Blue. The three primary color components in a TV system.

"RG", is the military designation for coaxial cable, and "U" stands for "general utility".

Right-Hand Circular Polarization.

"A microphone where the sound capturing element is a thin metal ribbon 
suspended in a magnetic filed. When sound causes the ribbon to vibrate, a small electrical current is generated within the ribbon."

A device that accepts and processes two input signals in a particular way. The 
output signal does not contain any of the original input signal but instead comprises new frequencies based on the sum and difference of the input signals' frequency components. Ring Modulators will be covered in depth later in the series. The best known application of Ring Modulation is the creation of Dalek voices but it may also be used to create dramatic instrumental textures. Depending on the relationships between the input signals, the results may either be musical or extremely dissonant - for example, ring modulation can be used to create bell-like tones. (The term 'Ring' is used because the original circuit which produced the effect used a ring of diodes.)

" (Root Mean Square) A method of specifying the behaviour of a piece of electrical 
equipment under continuous sine wave testing conditions. "

" The rate at which a filter attenuates a signal once it has passed the filter cut-off 

"Abbreviation for Read Only Memory. This is a permanent or non-volatile type of 
memory containing data that can't be changed. Operating systems are often stored on ROM as the memory remains intact when the power is removed."

Radio Receive Only (terminal).

The approximately 10 kHz to 100 GHz electromagnetic band of frequencies used for man-made communication.

Russian FSS satellite serving the STATSIONAR system in the C-band frequency range.

Loss of signal (esp. at Ku-band) due to absorption and thermal noise accompanying heavy rainfall.

The random pattern of illumination seem on a television screen when no video signal is present.

The maximum temperature at which an electric component can operate for extended periods without loss of its basic properties.

The maximum voltage at which an electric component can operate for extended periods without undue degradation or safety hazard.

A mechanical switch which uses two thin slivers of metal in a glass tube to make and break electrical contact and thus to count pulses which are sent to the antenna actuator controller. The position of the silver of metal is governed by a magnetic field applied by a bar or other type of magnet.

A highly stable signal used as a standard against which other variable signals may be compared and adjusted.

The part of a signal which is lost due to reflection of power at a line discontinuity.

The blanked-out line traced by the scanning beam of a picture tube as it travels from the end of any horizontal line to the beginning of either the next horizontal line or field.

A ratio of the amount of reflected signal to the total available signal entering a device expressed in decibels.

A conductor composed of a central core surrounded by one or more layers of helically laid groups of wires.

Satellite downlinks in the region of 2.6 GHz.

Signal-to Noise Ratio. A measure of how clean (noise-free) the recovered baseband signal is.

"Acronym for ""Sony/Philips Digital Inter Face""
The S/PDIF digital data format is very similar to the professional AES-EBU standard although it uses different electrical characteristics. The system normally carries 16 or 20-bit data, although it can accommodate 24-bits of audio data per channel."

The S/PDIF digital data format is very similar to the professional AES-EBU standard although it uses different electrical characteristics. The system normally carries 16 or 20-bit data, although it can accommodate 24-bits of audio data per channel. Extra information can also be carried along side the audio such as track start flags, source identification information, and timing data.

Copy or clone of an original tape for use in case of loss or damage to the original.

The process carried out by an A/D converter where the instantaneous amplitude of a signal is measured many times per second (44.1kHz in the case of CD).

The number of time an A/D converter samples the incoming waveform each second.

A digitised sound used as a musical sound source in a sampler or additive synthesizer.

A solid state filter that yields a sharp transition between regions of transmitted and attenuated frequencies.

So called because it resembles the teeth of a saw, this waveform contains both odd and even harmonics.

Single Channel Per Carrier. A narrowband transmission mode used to relay audio and data information.

(Pronounced SKUZZY) Abbreviation for Small Computer Systems Interface. An 
interfacing system for using hard drives, scanners, CD-ROM drives and similar peripherals with a computer.

Device for recording and replaying MIDI data, usually in a multitrack format, allowing complex compositions to be built up a part at a time.

The original tape made during a recording session.

Super high frequency.

The term is usually used to describe a current path that exists through a fault condition.

High frequency whistling or lisping sound that affects vocal recordings, due either to poor mic technique or excessive equalisation.

A part of the circuit that splits off a proportion of the main signal to be processed in some way. Compressor use the side-chain signal to derive their control signals.

Electrical representation of input such as sound.

Route taken by a signal from the input to a system to the output.

The ratio of maximum signal level to the residual noise, expressed in dBs.

The waveform of a pure tone with no harmonics.

A device for removing or attenuating the noise component of a signal, but that doesn't require previous coding, as in the case of Dolby or dbx.

A device under the control of a master device.

Satellite Master Antenna Television.

SMPTE is a real-time code and is related to hours, minutes, seconds and film or video frames rather than to musical tempo.

Early recording technique to allow pseudo-multitracking. Also, Europe's No.1 hi-tech music recording magazine.

Single channel per carrkier, PCM multiple - Access Demand - Assignment Equipment (SCPC phony sys).

Dual paylond lanuch adapter for Ariance.

Sound Pressure Level measured in dBs.

Song Position Pointer (MIDI).

A symmetrical rectangular waveform. Square waves contain a series of odd harmonics.

Satellite-Switched Time Division Multiple Access.

Single Side Band. A form of amplitude modulation (AM) whereby one of the sidebands and the carrier are supperssed.

Solid-State Power Amplifier. A transistor or FETHPA now increasingly replacing TVVTs in satellite transponder

A standard file format that allows MIDI files to be transferred between different 
equencers and MIDI file players.

A system for programming a sequencer in non-real time.

two-channel system feeding left and right loudspeakers.

A problem affecting some brands of analogue tape after a long time in storage. A
breakdown of the binder causes the oxide to shed, and the tape tends to adhere to the tape heads and guides when played. A short term cure can be affected by baking the affected tape for several hours at 50 degrees C.

Studio - Transmitter Link.

To record time code onto one track of a multitrack tape machine.

Space Transportation System (the Shuttle).

Frequencies below the range of typical monitor loudspeakers. Some define sub-bass as frequencies that can be felt rather than heard.

Hidden data within the CD and DAT format that includes such information as the absolute time location, number of tracks, total running time and so on.

The process of creating a new sound by filtering and shaping a raw, harmonically complex waveform.

Sudden increase in mains voltage.

Part of the ADSR envelope which determines the level to which the sound will settle if a key is held down. Once the key is released, the sound decays at a rate set by the Release parameter. Also refers to a guitar's ability to hold notes which decay very slowly.

The optimum position for a microphone, or for a listener relative to monitor loudspeakers.

A type of power supply that uses a high frequency oscillator prior to the transformer so that a smaller, lighter transformer may be used. These power supplies are commonly used in computers and some synthesizer modules.

A system for making two or more pieces of equipment run in synchronism with each other.

Electronic musical instrument designed to create a wide range of sounds, both imitative and abstract.

The indoors electronic component of an earth station which downcoverts, processes and prepares satellite signals, for viewing or listening.

Operating point of a non-liner amplifier when drive level is adjusted to obtain maximum osutput.

Colour intensity parameter in a video signal.

The wide flare corrugated horn antenna feed, commonly used in C-band home satellite TV receiving systems.

The organized process of moving the electron beam in a television picture tube so an entire scene is drawn as a sequential series of horizontal lines connected by horizontal and vertical retraces.

A method of altering the identity of a video or audio signal in order to prevent its reception by persons not having authorized decoders.

A metal, concrete or natural material that screens, out unwanted TI from entering an antenna or a metal shield that prevents the ingress of unwanted RF signals in an electronic circuit.

Sequence Couleur a Memorie. French-designed color TV encoding system.

The television vertical sync pulse which is subdivided into six serrations. These sub-pulses occur at twice the horizontal scanning frequency.

An oscillatory searching of the feedhorn probe when use of inadequate quage control cables results in insufficient voltage at the feedhorn.

Beam of irregular cross-section, produced by multiple feed or shaped reflector techniques.

Techniquesfor controlling beam pattern, aperture illumination, noise, and side lobe power, and for increasing antenna efficiency, by variation of antenna (and subreflector) shape from the true paraboloid, hyperboloid etc.

The outer covering or jacket of a multiconductor cable.

In cables, a metallic layer placed around a conductor or group of conductors to prevent electrostatic or electromagnetic interference between the enclosed wires and external fields.

The relative ability of a shield to screen out undesirable radiation. Frequently confused with the term shield percentage, which it is not.

Transmissions on frequencies of 6-25 MHz.

Sound-in-Syncs (audio/video multiplexing system). Strictly referes to digital version used by E.

A parameter used to describe an antenna's ability to detect off-axis signals. The larger the side lobes, the more noise and interference an antenna can detect.

The ratio of signal power to noise power in a specified bandwidth, usually expressed in decibels.

A satellite transmission system that employs a separate carrier for each channel, as opposed to frequency division multiplexing that combines many channels on a single carrier.

A term used to describe the adjustment necessary to fine tune the feedhorn polarity detector when scanning between satellites.

The phenomenon in which the depth of penetration of electric currents into a conductor decreases as the frequency increases.

The distance that a signal travel from a satellite to a TVRO.

Video noise or sparkiies caused by an insufficient signal-to- noise input ratio to a television set or monitor.

A network of solar cells which generate electricity when exposed to sunlight.

When the Earth shadows the satellite's solar array from the Sun.

The loss of reception that occurs when the sun is positioned directly behind a target satellite. When this occurs, solar noise downs out the satellite signal and reception is lost.

A test designed to locate pin-holes in the insulation of a wire or cable by application of a voltage for a very short period of time while the wire is being drawn through the electrode field.

Small black andlor white dashes in a television picture indicating an insufficient signal-to-noise ratio. Also known as "snow".

The ratio of the density (mass per unit volume) of a material to that of water.

The range of electromagnetic radio frequencies used in transmission of voice, data and television.

Simple geometry for feed-steerable multiple beam antenna.

An antenna system using a section of a spherical reflector to focus one or more satellite signals to one or a series of local areas.

Usable (but often unwanted) signal reaching locations beyond defined Edge of Coverage.

A form of satellite attitude control which is achieved through spinning the exterior of spacecraft about its axis at a fixed rate.

The helical wrap of a tape or thread over a core.

Component of a backfire feed system - an unshaped (or arbitrarily shaped) subreflector.

A device that takes a signal and splits into two or more identical but lower power signals.

Beam of circular or elliptical cross-section, covering a defined region of the Earth's surface, small in relation to a global beam.

A video test waveform, included in ITS.

Orbital adjustments to maintain satellite accurately at desired geostationary location.

Russian geostationary communications satellite systems.

Software-based automatic antenna tracking system.

A single uninsulated wire.

A conductor composed of groups of wires twistea together.

The force required to remove a small section of insulating material from the conductor it covers. Usually measured in pounds.

An information-carrying-wave, which in turn modulates the main carrier in a communications system. Subcarriers are used for color information, TV audio, independent audio, and data transmission.

The unique spot over the Earth's equator assigned to every geostationary satellite.

Television programming/channels that can be viewed in your home only if you pay for them. The signal of subscription satellite television channels is scrambled and beamed down. Only subscribers who have an IRD for those particular subscription services have access to them.

A sound or acoustic wave traveling on the surface of the optically polished surface of a pie zoelectric material. This wave travels the speed of sound but can pass frequencies as high as several gigahertz.

The resistance of a material between two opposite sides of a unit square of its surface. It is usually expressed in ohms.

Pertaining to cable, checking frequency response by generating an rf voltage whose frequency is varied back and fort through a given frequency range at a rapid constant rate and observing the results of an oscilloscope.

Type of Video scrambling (e.g., Oak Orion, Nimrod)

The process of orienting the transmitter and receiver circuits in the proper manner in order that they can be synchronized .

Pulses imposed on the composite baseband video signal used to keep the television picture scanning in perfect step with the scanning at the television, camera.

Telephony Tap - A device that channels specific amount of energy out of the main distribution system to a secondary outlet.


The part of a tape machine that transfers magnetic energy to the tape during recording, or reads it during playback.

Telecommand (control of a satellite).

Tunnel Diode Amplifier (early type of LNA).

French DBS satellite system.

Time Division (or Domain) Multiplex.

Turner/Demodulator (i.e., indoor Unit). often referred to as the receiver.

Time Division Multiple Access.

The rate of the 'beat' of a piece of music measured in beats per minute.

steady, fixed level tone recorded onto a multitrack or stereo recording to act as a reference when matching levels.

Total Harmonic Distortion.

MIDI connector which passes on the signal received at the MIDI in socket.

Terrestrial Interference. Interference to satellite reception caused by ground-based microwave transmitting stations.

The tonal 'colour' of a sound.

Telemetry. Satellite status data transmission.

Technical Operations Center.

The term dates back to multitrack tape where the tracks are physical stripes of 
recorded material, located side by side along the length of the tape.

The system whereby one device follows another. Tracking is often discussed in the context of MIDI guitar synthesizers or controllers where the MIDI output attempts to track the pitch of the guitar strings.

A device for converting one form of energy to another. A microphone is a good example of a transducer as it converts mechanical energy to electrical energy.

Subjective term used to describe audio quality where the high frequency detail is clear and individual sounds are easy to identify and separate.

To shift a musical signal by a fixed number of semitones.

Modulation of the amplitude of a sound using an LFO.

Symmetrical triangular shaped wave containing odd harmonics only, but with a lower harmonic content than the square wave.

Stereo type jack with Tip, Ring and Sleeve connections.

A metal bar within a guitar neck which is tensioned so as to counteract the tendency for the neck to bend under the tension of the strings.

Tracking, Telemetry, and Command (or Control)

Tracking, Telemetry, Command and Monitoring. A satellite's controlling Earth Station.

German DBS satellite system.

A television receive-only earth station designed only to receive but not to transmit satellite communications.

Traveling - Wave Tube.

Traveling - Wave Tube Amplifier.

A spirally applied tape over an insulated or uninsulated wire.

The force required to initiate or continue a tear in a material under specified conditions.

A textual data transmission system, linking word processing terminals.

Broadcast Videotex An on-screen text information service transmitted in digital formal using spare lines in the VBI of a TV signal.

A satellite system that can only receive but not transmit signals.

A telegraphic text transmission system, linking teleprinters.

Nordic DBS satellite system.

The pull stress required to break a given specimen.

Random, undesired electrical signals caused by molecular motion, known more familiarly as noise.

Type of spacecraft stabilization in which the body maintains a fixed attitude relative to the orbital track and the earth's surface. The reference axes are roll, pitch, and yaw, by nautical analogy.

A minimal signal to noise input required to allow a video receiver to deliver an acceptable picture.

Techniques for reducing the CNR value at which threshold effects occur.

A small rocket engine used during routine station keeping activities.

The uneven attenuation of a broadband signal as it travels through a coaxial cable. In general, attenuation increases as signals frequency increases.

Parabolic Torus geometry of multiple beam antenna. Reflector has a circular profile along the orbital arc, and a parabolic profile across the are.

The movement of the electron beam from left to right on a television screen.

The telecommunications signals passing through a transmission channel, especially telephony, data.

A highly elliptical orbit which is used as an intermediate stage for placing satellites into geostationary orbit.

Two or more transmission lines. If the structure is flat, it is sometimes called Flat Transmission Cable to differentiate it from a round structure such as a jacketed group of coaxial cables.

Structure providing a (usually low-loss) pathway for a radio-frequency signal. In satellite communications, usually coaxial cable or waveguide.

An electronic device consisting of oscillator, modulator and other circuits which produce a radio or television electromagnetic wave signal for radiation into the atmosphere by an antenna.

A combination receiver, frequency converter, and transmitter package, physically part of a communications satellite. Transponders pick up signals transmitted from earth, translates them into new frequencies and amplifies them before retransmitting them back to ground. Transponders have a typical output of five to ten watts, operate over a frequency band with a 36 to 72 megahertz bandwidth in the L, C, Ku, and sometimes Ka Bands or in effect typically in the microwave spectrum, except for mobile satellite communications. Communications satellites typically have between 12 and 24 onboard transponders although the Intelsat VI at the extreme end has 50.

An electronic device that attenuates a selected bank of frequencies in a signal. Also known as a notch filter.

A cable tray system is a unit or assembly of units or sections, and associated fittings, made of metal or other noncombustible materials forming a rigid structural system used to support cables. Cable try systems (previously termed continuous rigid cable supports) including ladders, troughs, channels, solid bottom trays, and similar structures.

A cable construction having three coincident axes, such as conductor, first shield and second shield all insulated from one another.

Loss or outermost side frequencies of an FM signal due to filtering. Shows as "tearing" effect of noise on video transients, sharp vertical edges.

The spectrum 300 MHz through 3 GHz. Terrestrial broadcasts television occupies 470-890 MHz. The 620-790 MHz band is allocated for community DSS downlinks in developing countries and remote areas.

Abbreviation for Underwriters Laboratodes, a nonprofit independent organization, which operates a listing service for electrical and electronic materials and equipment.

A 2-wire electrical signal connection where the inner or hot or +ve (positive) conductor is usually surrounded by the cold or -ve (negative) conductor, which forms a screen against electrical interference.

To play the same melody using two or more different instruments or voices.

(Universal Serial Buss) A high-speed serial communications protocol which allows (theoretically) up to 127 hot-swappable peripherals to be connected in daisy-chain fashion. USB devices can be unplugged/plugged in without having to reboot your computer. Popular on modern PCs and associated computer peripherals (printers, scanners etc) but also adopted by Apple on their iMac and blue G3 machines onwards

Universal Time. Same as GMT.

A device that increases the frequency of a transmitted signal.

The earth station electronics and antenna which transmit information to a communication satellite.

A band of frequencies in the 10.9 to 17 GHz range that are used for fixed satellite service applications.

Vacuum tube amplification component, also known as a tube.

Vertical-Blanking Interval (Of TV signal), U.S. terminology. Otherwise known as field Suppression.

Visual/Display Unit. TV-type monitor used as a computer display.

The rate at which a key is depressed. This may be used to control loudness (to simulate the response of instruments such as pianos) or other parameters on later synthesizers.

Abbreviation for very high frequency, 30 to 300 Mhz.

Very High Resolution Radiometer.

Pitch modulation using an LFO to modulate a VCO.

Vertical-interval Test Signal (US); Vision Insertion Test Signal (Europe). See ITs.

Signal processor that imposes a changing spectral filter on a sound based on the frequency characteristics of a second sound. By taking the spectral content of a human voice and imposing it on a musical instrument, talking instrument effects can be created.

The capacity of a synthesizer to play a single musical note. An instrument capable of playing 16 simultaneous notes is said to be a 16-voice instrument.

The ratio between the minimum and maximum voltage on atransmission line. An ideal VSWR is 1.0. Ghosting can result as the VSWR increases. It is also a measure of the percentage of reflected power to the total power impinging upon a device.

Voltage Tuned Oscillator.

Meter designed to interpret signal levels in roughly the same way as the human ear, which responds more closely to the average levels of sounds rather than to the peak levels.

A flammability rating established by Underwriters Laboratories for wires and cables that pass a specially designed vertical flame test, formerly designated FR-1.

The speed of an electrical signal down a length of cable compared to speed in free space expressed as a percent. It is the reciprocal of the square root of the dielectric constant of the cable insulation.

A pulse used during the vertical retrace period at the end of each scanning field to extinguish illumination from the electron beam.

A series of pulses which occur during the vertical blanking interval to synchronize the scanning process at the television with that created at the studio. See also Serrated Vertical Pulse.

A television that accepts unmodulated baseband signals to reproduce a broadcast.

A transmission cable containing low-loss pairs with an impedance of 125 ohms. Used for TV pick ups, closed circuit TV, telephone carrier circuit, etc.

That portion of the transmitted television signal containing the picture information.

An electronic textual information distribution system, from a central computer to remote VDUS. (Also See Teletext, Viewdata).

Interactive videotex.

A unit of electromotive force.

The highest voltage that may be continuously applied to a wire in conformance with standards or specifications.

An electronic circuit whose output oscillator frequency is adjusted by voltage. Used in downconverters and satellite receivers to select from among transponders.

Guitar effects device where a bandpass filter is varied in frequency by means of a pedal control.

Subjective term used to describe sound where the bass and low mid frequencies have depth and where the high frequencies are smooth sounding rather than being aggressive or fatiguing. Warm sounding tube equipment may also exhibit some of the aspects of compression.

Unit of electrical power.

A graphic representation of the way in which a sound wave or electrical wave varies with time.

A random signal with an energy distribution that produces the same amount of noise power per Hz.

The precise and accurate timing of digital audio samples is critical to the correct operation of interconnected digital audio equipment. The 'metronome' that governs sample timing is called the Word Clock (sometimes conjoined to 'Wordclock', or abbreviated to 'Wclk'). However, word clock does more than merely beat time; it also identifies the start and end of each digital word or sample, and which samples belong to the left or right channels. Digital interfaces such as the AES-EBU and S/PDIF embody clock signals within the data stream, but it is often necessary to convey a discrete word clock between equipment as a square wave signal running at the sampling rate. Dedicated word clock inputs and outputs on digital equipment generally use BNC connectors (the kind of terminals commonly used for video).

To save data to a digital storage medium, such as a hard drive.

The thickness of the applied insulation or jacket.

A unit of electric power.

The distance, measured in the direction of propagation, of a repetitive electrical pulse or waveform between two successive points that are characterized by the same phase of vibration.

A rectangular or oval metal pipe that is commonly used as a transmission line for microwave signals. The dimensions and tolerances of waveguides are directly related to the wavelength of the microwave signals which they are to carry.

Proprietary system for subcarrierstereo (or additional audio) transmission. Uses discrete low-level companded subcarriers.

Correction of SNR measurements to take into account such factors as bandwidth and annoyance value.

A conductor, either bare or insulated.

The two planes of polarization in the Eutelasat system, nominarry horizontal and vertical, respective.

Used loosely to refer to satellites operating in the 8/7 GHz range.

An antenna mount permitting independent steering about two orthogonal axes, not necessarily rel to azimuth or elevation.

"Yamaha's alternative to Roland's GS system for enhancing the General MIDI protocol so as to provide additional banks of patches and further editing facilities."

"Type of connector commonly used to carry balanced audio signals including the feeds from microphones. "

Cross-polar discrimination (of an antenna)

A method of measuring noise figure and G/T.

Lead split so that one source can feed two destinations. Y leads may also be used in console insert points in which case a stereo jack plug at one end of the lead id split into two monos at the other.

An alternative assembly of color components. Y is the Luminance signal, U and V are normal versions of the Blue and Red colour-difference signals, B-Y and R-Y.

A communications antenna consisting of a main metal boom that supports various numerous quarter-wave elements. S- and C- band models are available for reception of Arabsat and Asiasat TV services.

Parameter of tape head alignment relating to whether or not the head is perpendicular to the tape path, and aligned so as to be in the same plane.

The point at which a signal waveform crosses from being positive to negative or vice versa.

Audible steps that occur when a parameter is being varied in a digital audio processor.

Beam pattern, usually a shaped bearn,intermediate between hemispheric and spot.