Home Theater, Surround Sound, Television, Low Voltage Structured Wiring

Glossary of Terms

Home Theater, Surround Sound, Television, Low Voltage Structured Wiring - Glossary

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10BaseT	Standard developed by Institute of Electrical Engineers ( IEEE ) refering to 24-AWG unshielded twisted pair wiring with a baseband medium of 10 Mbps, and defines various aspects of running Ethernet on this cabling.
10Base2	IEEE standard for thin coax with maximum length of 656 ft, having a baseband medium of 10 Mbps
100BaseT	Standard developed by Institute of Electrical Engineers ( IEEE ) refering to 24-AWG unshielded twisted pair wiring with a baseband medium of 100 Mbps, and defines various aspects of running Ethernet on this cabling.
1000BaseT	Standard developed by Institute of Electrical Engineers ( IEEE ) refering to 24-AWG unshielded twisted pair wiring with a baseband medium of 1000 Mbps, and defines various aspects of running Ethernet on this cabling.
3-2 pulldown processing	Sophisticated video processing common to digital TVs and progressive-scan DVD players. It corrects for artifacts and distortion that occur when film-based material (at 24 frames per second) is converted to video (30 frames per second), then de-interlaced to create a progressive-scan signal.
5.1, 6.1, and 7.1-channel inputs	A receiver's 5.1-channel input features preamp-level jacks for 6 channels: left main, right main, center channel, left surround, right surround, and subwoofer (sometimes called "LFE" or "Low-Frequency Effects"). Because the LFE channel carries a limited range of very low frequencies, it's the ".1" in 5.1. A 5.1-channel input allows you to hook up a separate multichannel surround sound (Dolby® Digital, DTS®) decoder, such as those built into some DVD players. You can also use these inputs with up-and-coming multichannel music sources like DVD-Audio and SACD players. Some receivers feature a 6.1 or 7.1-channel input. These let you hook up any of the 5.1 sources described above, but also pave the way for future upgradability. One potential use for these inputs is hooking up decoders for surround formats that offer 6.1 channels, such as Dolby™ Digital EX, DTS-ES™ and THX Surround EX™.
5.1-channel surround sound	A setup with six discrete digital audio channels: five full-bandwidth and one "low frequency" channel. The full-bandwidth channels account for the front left and right speakers, the center speaker, and the back left and right surrounds, while a subwoofer takes care of the low-frequency effects. This set-up is used in home living rooms, media rooms, game rooms and smaller sized dedicated home theaters.
6.1-channel surround sound	A setup with seven discrete digital audio channels: six full-bandwidth and one "low frequency" channel. The full-bandwidth channels account for the front left and right speakers, the center speaker, surround left and right speakers and the back center surround, while a subwoofer takes care of the low-frequency effects. This set-up is used in home living rooms, media rooms, game rooms and small to medium sized dedicated home theaters.
7.1-channel surround sound	A setup with eight discrete digital audio channels: seven full-bandwidth and one "low frequency" channel. The full-bandwidth channels account for the front left and right speakers, the center speaker, surround left and right speakers and the back left and right surrounds, while a subwoofer takes care of the low-frequency effects. This set-up is used in home living rooms, media rooms, game rooms and medium to large sized dedicated home theaters.
7.2-channel surround sound	A setup with nine discrete digital audio channels: seven full-bandwidth and two "low frequency" channel. The full-bandwidth channels account for the front left and right speakers, the center speaker, surround left and right speakers and the back left and right surrounds, while two subwoofers takes care of the low-frequency effects. This set-up is used in home living rooms, media rooms, game rooms and large sized dedicated home theaters.
9.1-channel surround sound	A setup with ten discrete digital audio channels: nine full-bandwidth and one "low frequency" channel. The full-bandwidth channels account for the front left and right speakers, the center speaker, surround left and right speakers, back surround left and right speakers and the back left and right presence speakers, while a subwoofer takes care of the low-frequency effects. This set-up is used in home media rooms, game rooms and large sized dedicated home theaters.
10.2-channel surround sound	A setup with twelve discrete digital audio channels: ten full-bandwidth and two "low frequency" channel. The full-bandwidth channels account for the front left and right speakers, the center speaker, left high and right high, left wide and right wide, surround left and right and surround back center, while two subwoofer left and right between wide channels and surrounds takes care of the low-frequency effects. This set-up could be used in large sized dedicated home theaters.
22.2-channel surround sound	A setup with twenty four discrete digital audio channels: twenty two full-bandwidth and two "low frequency" channel. Not enough information to complete.
A / D converter	Analog to digital converter - A device that converts an analog value to a digital value.
A / V	Industry term for audio/visual, or audio/video.
A / V inputs (TV)	Using a TV's direct A/V inputs to connect a DVD player, VCR, camcorder or other video component provides improved picture and sound quality compared to using the everything-on-one-wire RF antenna-style input. (If your TV is old enough that it only has RF-type inputs, that's reason enough to consider replacing it - DVD players don't normally have an RF output!) Rear A/V inputs are used for components you normally leave connected to your TV. Front A/V inputs allow you to quickly and easily connect/disconnect a camcorder, second VCR, or video game console.
A / V inputs / outputs (Receivers)	An A/V input consists of three RCA jacks - two for the stereo audio signal, and one for the video signal. Receivers with A/V inputs offer convenient remote switching for your A/V sources.
AAC (Advanced Audio Coding)	An up-and-coming compression format for digital audio. In terms of sound quality and data efficiency, AAC solidly beats the still-popular MP3 format - not surprising, since AAC is a newer, more advanced form of compression. According to some listening tests, AAC files encoded at lower bitrates (like 96 Kbps) sound as good or better than MP3s encoded at higher bitrates (like 128 Kbps) despite their notably smaller size. The current version of the AAC codec was developed as part of the MPEG4 standard. AAC is the audio file format used by Apple in their popular iTunes Music Store.
AC-3	The first descriptor for what is now called Dolby Digital.
AC	Alternating current. Electron flow that changes direction alternately.
AC coupled	When a circuit does not pass DC component of signal, and it ignores DC offsets.
AC Line Conditioner or Protector	A device inserted between the wall outlet and your equipment to isolate it from voltage spikes and unwanted high frequency signals that may be picked up by the power lines. High quality audio equipment may already have some of this kind of isolation built in. See also: AC Voltage Stabilizer
AC Voltage Stabilizer	A device inserted between the wall outlet and your equipment to maintain a constant voltage level. Used in buildings and neighborhoods where line voltage fluctuates widely because of heavy variable loads.
Acoustics	The physical science dealing with how sound is produced, propagated, manipulated and perceived. See also: Room Acoustics
Acoustic suspension	A type of speaker enclosure that uses a sealed box to provide tight, accurate bass response. It gives up some efficiency to provide bass that is more accurate and controlled, so compared to a bass reflex design, it may require more amplifier power to play at the same volume level. See also bass reflex.
Acoustical Interference	When two or more sounds arriving from different directions combine at a point in space, e.g. at an ear or microphone, those components which are in step with each other (in phase) will add (constructive interference) and those that are out-of-phase will subtract, or cancel each other (destructive interference). See: In Phase, Out-of-Phase, Comb Filter.
Achromatic	Completely colorless white light.
Active Crossover	An analog or digital device performing high-pass, low-pass and bandpass functions ahead of power amplifiers driving the transducers in a loudspeaker.
Active Loudspeaker	A loudspeaker which has a built-in power amplifier for at least one driver, usually the woofer or subwoofer. It may also have amplifiers for mid and high frequency drivers. See: Powered Tower
Active Matrix Decoder	See: Matrix Encode/Decode
ADA	Analog Distribution Amplifier.A device that takes in one signal and distributes it to several outputs without "tying" those outputs together (buffered).
Adapter	Device enabling different types or sizes of plugs to mate.
ADC	Analog-to-digital converter.A device used to convert analog signals to digital signals.
Additive color process	Also called "RGB". A color generation process used in video that combines red, green and blue to make all colors. All three colors (red, green and blue) at 100% combine to make white on a video screen; the absence of all three colors (0%) makes black. Also see subtractive color (CMYK)
ADSP™	Advanced Digital Sync Processing™. Using sync processing to allow centering control (H-shift or V-shift) can create problems with some display devices because of the sync delay. This means the digital projector user may have to choose between a stable sync and centering control.
ADTV	Advanced Definition Television. An early version of high definition television (HDTV) devised in Japan. Now superseded by US HDTV standards.
AES/EBU	The two-channel digital audio communication process that was standardized by the Audio Engineering Society (AES) and the European Broadcasting Union (EBU).
AFL™	Accu-RATE Frame Lock™. A method of eliminating image tearing which is associated with scaling, especially when motion video is involved, and occurs when the input frame rate is slower or faster than the output frame rate and part of the old frame and part of the new frame are displayed at the same time during a refresh cycle.
AGC	Automatic Gain Control. In audio recording, a circuit used to automatically control the volume of the recorded signal without distortion due to overload. It is sometimes called Automatic Level Control (ALC), or Automatic Volume Control (AVC).
AIFF (Audio Interchange File Format)	An audio format for Macintosh operating systems commonly used for storing uncompressed, CD-quality sound (similar to WAV files for Windows-based PCs).
Aliasing	Aliasing occurs when smooth curves and lines become rough or jagged because of a lower resolution device, or by an event. In analog video, aliasing is typically caused by interference between the luma and chroma frequencies or between the chroma and field scanning frequencies. It appears as a moiré or herringbone pattern, straight lines that become wavy, or rainbow colors. (Also see cross color.) In digital video, insufficient sampling or poor filtering of the signal causes aliasing. Defects typically appear as jagged edges on diagonal lines and twinkling or brightening in picture detail. See antialiasing.
ALiS	ALiS (Alternate Lighting of Surfaces) is a relatively new type of high-definition plasma panel design. On a conventional plasma TV, all pixels are illuminated at all times. With an ALiS plasma panel, alternate rows of pixels are illuminated so that half the panel's pixels are illuminated at any moment (somewhat similar to interlaced-scanning on a CRT-type TV). ALiS panels offer bright, clear picture quality, reduced power consumption, and extended panel life.
AM (radio) Amplitude Modulation	A method of radio transmission, by which the information part of the signal causes the amplitude to vary without affecting the frequency.
Ambience	In audio this refers to the reflected and reverberant sound characteristics of an acoustic space. All rooms can be acoustically 'live' or 'dead'. Large rooms can be flattering to musical performances (concert hall) or hostile (gymnasium).
American Standard Code for Information Interchange	It is the standard code consisting of 7-bit coded characters (8 bits including parity check), utilized to exchange information between data processing systems, data communication systems, and associated equipment. The ASCII set contains control characters and graphic characters.
American National Standards Institute	ANSI - The American National Standards Institute is the organization that sets standards for US A/V equipment.
American Wire Gauge (AWG)	Standard gauge for measuring diameter of copper, alluminum and other conductors.
Ammeter	A device used to measure current flow in amperes.
Amorphous	1-No definite form or shape; not crystallized.2-Early type of LCD panel technology before polysilicon.
Amp - Ampere	The international base unit of current that represents the rate flow of electric charges through a conductor. Symbolized by "A". One amp is equal to the steady current produced by 1 volt applied across a resistance of 1 ohm.
Amperage	The magnitude of an electrical current as expressed in amperes.
Ampere-hour	A measure of the quantity of electricity delivered by a battery determined by multiplying the integrated current in amperes by the duration of the current flow in hours.
Ampere-hour capacity	Rating for a battery describing current in amperes that can be drawn over a period of time in hours before the discharge limit is exceeded.
Amplification	An increase in signal level.
Amplifier	Device used to increase the strength of a signal. An electronic device that takes in an original signal, gives it more power and provides it as an output.
Amplitude	The level or strength of a signal as measured by the height of its waveform. Electronic waveforms can be displayed and measured on an oscilloscope.
Amplitude Modulation	A method of radio broadcasting in which the radio carrier frequency is amplitude modulated by the audio signal. Typically limited in bandwidth, and susceptible to interference and static. However, it propagates well over long distances and around hills and buildings. Abbreviated AM.
Analog	A continuously varying action, or movement that takes time to change from one position to another. Standard audio and video signals are analog. An analog signal has an infinite number of levels between its highest and lowest value. (Not like digital, where changes are by steps.)
Analog control	Method using continuously varying voltage levels to provide control of equipment.
Analog recording	Method of recording and encoding information by use of a continuously varying signal, rather than by discrete (digital) pulses.
Analog-to-digital converter	See A/D converter.
Anamorphic	A type of lens or adapter designed to produce a wide-screen image from a condensed image on the film. Trademarks are held by CinemaScope, Panavision and Vistavision.
Anamorphic DVD	A DVD that has a widescreen video image that has been horizontally squeezed. This allows a full widescreen image to be displayed on a 16x9 screen.
Anamorphic video	Video images that have been "squeezed" to fit a video frame when stored on DVD. These images must be expanded (un-squeezed) by the display device. An increasing number of TVs employ either a screen with 16:9 aspect ratio, or some type of "enhanced-for-widescreen" viewing mode, so that anamorphic and other widescreen material can be viewed in its proper proportions. When anamorphic video is displayed on a typical TV with 4:3 screen size, the images will appear unnaturally tall and narrow.
Anechoic	Without echoes, reflections or reverberation.
Anechoic Chamber	A room without echoes or reflections that is used for precise acoustical measurements, not contaminated by normal room acoustical factors, including noise. It is the ultimate 'dead' room. See Reverberation.
Anode	The electrically positive terminal of a battery, or the plate of a vacuum tube.
Antialiasing	In computer graphics, antialiasing is a technique for smoothing jagged edges by blending shades of color, or gray along the edges. Some video devices, such as character generators, have an antialiasing feature to minimize aliasing through filtering and other techniques.
Aperture	The opening, usually an adjustable iris, which controls the amount of light passing through a lens. In motion picture cameras, the mask opening that defines the area of each frame exposed. In motion picture projectors, the mask opening that defines the area of each frame projected.
Aperture grill	A screen-like feature of Sony Trinitron monitors and others licensed by Sony which controls the number of electrons hitting the phosphor coating on the screen.
Aperture Ratio	In digital display devices, this is a measure indicating the percentage of the available area that is used for active pixels. Some displays have obvious inactive 'frames' around individual pixels, leading to the description 'screen-door' effect when viewing such a display from insufficient distance.
Aquaplas	A water based compound high in particulates which is used to adjust the mass of, and to add damping to, a variety of loudspeaker diaphragm materials.
Articulation / Articulation Index	Having to do with the intelligibility of speech. This is measured using listeners who try to identify randomly presented 'nonsense' words and phrases. The Articulation Index is the percentage of correct identifications. Used mainly in large venues.
Artifacts	Artifacts are visible corruption of the image or undesirable elements or defects in a video picture created by disturbances in the video transmission or processing. These may occur naturally in the video process but must be eliminated to produce a high quality picture. The most common reasons for video artifacts are cross color and cross luma. Examples include "dot crawl" or "hanging dots" in analog pictures, or "pixelation" in digital pictures.
Artificial Reverberation	Synthesized reflected sounds intended to add to a recording the acoustical impression of being in a specific size and kind of room, such as a concert hall, stadium, club, etc. Inexpensive versions tend to be very artificial sounding. The best versions are hardly distinguishable from the real thing, and in fact are used in numerous concert performing spaces to improve on less-than-perfect natural acoustics. Also, the electronic reverberation added to close-miked recordings.
Aspect ratio	The ratio of width to height for an image or screen. The North American NTSC television standard uses the squarish 4:3 (1.33:1) ratio. More and more direct-view and projection TVs (especially digital TVs) use the wider 16:9 ratio (1.78:1) to better display widescreen material like anamorphic DVDs and HDTV broadcasts.
ASTA - Active Sync Termination Adapter	A VGA-style (15-pin HD connector) adapter that provides active circuits that shape up the horizontal and vertical sync signals. This adapter may be used to eliminate jitter and/or intermittent tearing in the displayed image. Most small digital projectors are designed to be near the video source and may not provide impedance matching. Also see LSTA.
Asynchronous	Intermittent, not synchronized or continuous. A "conversational" type of communication that allows the parties at each end to "talk" when they like instead of at a prescribed time. Used in videoconferencing.
ATM	Asynchronous transfer mode. In videoconferencing, a system for transmission and switching of digital signals through the telephone system.
ATRAC	Developed by Sony engineers in the early 90's, ATRAC is an audio codec which offers near-CD sound quality. The MiniDisc format uses ATRAC to fit a whole CD's worth of music on a 2-1/2" disc. ATRAC3 is a newer version of this codec that squeezes music into even smaller files. It's used for MDLP recording with some MiniDisc recorders, for music storage in some portable memory players, and in other Internet music applications like Liquid Audio and RealAudio. A MiniDisc recorder with MDLP gives you a range of compression options (in order of increasing compression): * regular recording mode - standard ATRAC codec (292 Kbps encoding bitrate), * LP2 mode - ATRAC3 codec (132 Kbps encoding bitrate), * LP4 mode - ATRAC3 codec (66 Kbps encoding bitrate)
ATSC	Advanced Television Standards Committee. Formed to establish technical standards for the U.S. digital television system,including digital high definition television (HDTV).
Attack	In music, the onset of a sound or note.
Attenuate/Attenuation	Reduction in power or strength (amplitude) of a transmitted signal as the signal travels along the cable. Attenuation is caused by capacitance, inductance and resistice losses in the cable. Attenuation is a function of frequency. Genrally, the greater the frequency, the more attenuation. Attenuation is also a function of distance. The greater the distance, the more attenuation. Attenuation is expressed as decibels/unit length and expresses a power loss per distance traveled. Also, frequency must be stated otherwise the data is useless. For example, attenuation specs stated as 6.5 db/1000m@10MHz means that the signal has lost 6.5 decibels of power over the 1000 meters of cable it traveled at a frequency of 10MHz. Attenuation is always present on a cable, as i capacitance. To improve error rates and achieve the reliable data transmission, the communications cable should have the lowest practical combination of the two.
AU	An audio format commonly used for posting sound clips on the Internet. AU files can be played back on Windows, Macintosh, and other operating systems.
Audio inputs / outputs (Receivers)	An audio input consists of two RCA jacks - one for the left stereo channel and one for the right. It can be used with most audio components with analog output. The major exception to this rule is turntables, which require either specialized audio input, called a phono input, or a phono preamplifier.
Audio follow	Term used when audio is tied to other signals, such as video, and they are switched together. The opposite of breakaway.
Audio Frequency Range	The range of human hearing commonly accepted as 20 to 20,000 Hertz (cycles per second).
Audio Interconnect Cable	A shielded wire used to link the audio signal output of one device to the input of another audio device.
Audiometer	A device for testing various aspects of hearing performance, beginning with the hearing threshold, the smallest sound that one can hear at various stantardized frequencies.
Audio Oscillator	A test instrument that produces single frequency tones for measuring the performance of audio devices.
Audio outputs (TV)	Stereo audio jacks that let you connect your TV to your stereo or home theater system. There are two types - fixed, and variable. If you connect a TV's fixed output to your A/V receiver, you'll be able to raise and lower the TV volume via the receiver's volume control. If you connect the TV's variable output to your receiver, you would control TV volume using the TV's remote.
Audiophile	Anyone interested in the reproduction of sound.
Audio Signal	An audio frequency signal in electronic form or after conversion to sound.
Auto-termination	In equipment that has loop-through, or "daisy-chain" connections, termination is done at the last device on the chain. Some such devices provide termination automatically by having no cable going out, thus indicating that this is the last device and termination is provided.
Automatic convergence	Automatic alignment of the red, green and blue color images on a screen.
Automatic sync stripping	Automatic removal of sync signals from video channels. Typically, this is associated with removing the sync signal from the green channel, but it may apply to stripping the sync off of all three video channels (Red, Green, and Blue).
Autosequencing	A switcher feature that causes the switcher to automatically select each one of its channels in succession, repeatedly sequencing through all channels.
Autosizing	Automatic picture sizing adjustment to compensate for different display modes, then enabling the display system to center the picture and fill the screen.
Autoswitching	Feature which enables a product to detect which input has an active sync signal and to switch to that input.
AVI (A / V Interleaved)	A file format for storing and playing back movie clips with sound on Windows-based PCs. An AVI file is organized into alternating ("interleaved") chunks of audio data and video data. AVI is a "container format," meaning that it specifies how the data will be organized, but it is not itself a form of audio or video compression. Digital video fans may be familiar with AVI as the type of file that's created when DV clips are imported from a digital camcorder to a PC. (These clips are often referred to as "DV-AVIs" because they contain full-quality DV content.)
Axial Modes	The acoustical resonances in rooms that occur between opposing parallel surfaces: walls, or floor and ceiling. See Room Resonances.
Azimuth	The angular distance (side to side) from true north, along the horizon, to the DBS satellite, measured in degrees. During installation of your DBS system, you (or the installer) can punch your zip code or latitude and longitude into the DBS receiver's setup screen and get precise azimuth and elevation angles for your location. You need this information to make sure that your dish is accurately aimed at the satellite.

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