Technical Glossary
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Displaying 56 glossary terms found.


I Signal
Color video signal transmitted as amplitude modulation of the 3.58 MHz C signal. Hue axis is orange and cyan. This is the only color video signal with bandwidth of 0 to 1.3 MHz.

Input/Output. Refers to the flow of information or signals (in and out) with respect to a computer or other device.

Integrated Circuit. Combining many circuits into one microminiature silicon module or "IC chip,"consisting of thousands or even millions of transistors (together with other components). Usually no bigger than a fingernail, often much smaller.

International Communications Industries Association. The official association of the A/V/video/multimedia industry. Formerly National Audio Visual Association (NAVA).

In a graphical user interface, an on-screen symbol that visually represents a program file, date file or some other computer entity or function.

Improved Definition Television. Intermediate system designed to improve resolution of existing NTSC standard without involving new transmission standard. Example: scan doubling or scan quadrupling. IDTV sets, through special circuitry, produce non-interlaced scan images for improved picture quality. However, over the years, there have been problems with IDTV images, in that there can be motion artifacts or "picture lag" effects. This has been caused by lack of computer memory on the part of the TV. While greatly improved today, IDTV direct view CRT sets have fallen out of fashion. To greatly improve resolution, a depicted IDTV line doubler, quadrupler, or scaler such as the Interpolator is a much better way to go. Some Front Projection and Rear Projection models are packaged with scan doublers.

International Electrotechnical Commission. The body whose responsibility it is to develop international standards for A/V. ICIA cooperates with IEC sub-committee SC-60.

IEC Connector
The standard AC power connector used on the back of power supplies, computers and other electronic equipment.

Intermediate Frequency - That to which a signal is shifted within a receiver for amplification. The first stage in converting a broadcast television signal into baseband video and audio.

Image Light Amplifier. The ILA is a liquid crystal technology, not to be confused with LCD that uses low-intensity images to modulate high-intensity light through a liquid crystal layer. This is a single liquid crystal for the entire image. Hughes/JVC is responsible for the most successful implementation of the technology. The ILA relies on another imaging device to create the picture. It is a light amplifier for that image. In most cases the imager for the ILA is a CRT. The resolution of the picture is often limited by the CRT, not the ILA. This makes this type of technology important when it comes to picture resolution. The CRT projector behind the ILA can be a limiting factor in the ILA's performance. AmPro Corporation also offers its own version of the liquid crystal technology.

IM Distortion
Intermodulation Distortion. Distortion caused when both high and low frequency tones intermix to produce a third, unnatural tone. Expressed as a percentage, the lower the better.

A scene recorded and displayed by any combination of visual media.

Image Enhancement
Techniques for increasing apparent sharpness without increasing actual resolution. Over enhancement results in artifacts.

Image Enhancer
A television signal processor creating a sharper picture by increasing luminance detail without increasing actual resolution.

Image Light Amplifier
See ILA.

1) The ability of a stereo pair of loudspeakers in an audio system to place sounds at specific locations between them so they can be realistically spatially characterized. 2) In video, the process of generating a video image.

Imaging Science Foundation
See ISF.

Impact Isolation Class
IIC. A system for rating the ability of a structure to isolate impact noise (i.e. footsteps, and other vibrational disturbances). Normally used in reference to floor and ceiling constructions, the IIC method utilizes whole positive numbers for rating purposes.

Impact Noise
The noise heard as a result of vibrations transferred through the structure of a room. Foot thumps are impact noise.

1) Z. A complex combination of reactive components (the opposition or "load" to a signal, measured in ohms), otherwise known as capacitance and inductance, and the resistive characteristics of the wire. It is determined by the ratio of the size of the center conductor and the distance between the center conductor and the outer shield. In video, typical low impedance circuits (low Z) are 600 ohms or less and high impedance circuits (high Z) may be 10k ohms or more. Video termination impedance is 75 ohm. See High Impedance and Low Impedance. 2) The opposition to the flow of electric or acoustic energy measured in ohms

Circuits that generate audio or video signals, are designed to work with a certain "load," or impedance. When connecting devices in a system, it is important that the impedance specifications are adhered to. If the impedance of the load is not matched to that of the source, there could be undesirable results, such as loss or distortion of the original signal, reflections, etc.

Improved Definition Television

A very short, transient, electric or acoustic signal. In phase Two periodic waves reaching peaks and going through zero at the same instant are said to be "in phase."

Impulse Response
The measured frequency response of a device's output when it is set in motion by a pulse.

In-Band Pink Noise
Filtered noise used for test purposes. This could be 20Hz to 80Hz for a subwoofer or 250Hz to 2.5kHz for the main audio system.

In-Band Pink Noise
Filtered noise used for test purposes. This could be 20Hz to 80Hz for a subwoofer or 250Hz to 2.5kHz for the main audio system.

Describes a direct view picture tube in which the electron guns are arranged side-by-side, as opposed to triangular arrangement.

Incident (Energy)
The sound energy arriving at or striking a surface.

Sponsors of the INFOCOMM (International Communications Industries Association) Projector "Shoot-Out," in which multiple images shown on all classes of projectors are compared.

IR. Light/heat waves just beyond the visible spectrum; that is, waves slightly longer than those visible to the human eye. Filtered out to reduce heat on film or slides.

Infrared Remote Control
A medium of remote control where signals are sent to a piece of equipment via pulses transmitted in the infrared light spectrum. Restricted to equipment within line-of-sight or reflections off a wall or ceiling. Also known as Wireless Remote Control.

Initial Time-Delay Gap
The time gap between the arrival of the direct sound and the first sound reflected from the surfaces of the room.

1) To enter data into a device or file. 2) The physical connector or port for entering such data.

A material that stops the flow of current.

Integrated Amplifier
A component that functions both as a pre-amplifier and a power amplifier.

Integrated Circuit
See IC.

The amount of sound energy radiated per unit area, measured in watts per square centimeter.

Interactive Video
The fusion of video and computer technology. A video program and a computer program running in tandem under the control of the user.

A shielded wire with plugs at both ends to pass signals from one device to another.

(Noun) A device or module that operates as a link between other dissimilar modules, usually because those modules cannot communicate directly with each other. An interface may act as a translator, or interpreter, and could be in the form of hardware and/or software. A video interface allows computer-video to be used by large screen video displays.

Electrical signals that have an undesirable effect on TV reception.

A process used in most television sets in which odd- and even-numbered lines of a picture are transmitted consecutively as two separate fields and superimposed to create one frame or complete picture on the screen. A picture is made up of two fields. Interlacing is the process of scanning the picture onto a video screen whereby the lines of one scanned field fall evenly between the lines of the preceding field. The manner in which the two video fields combine to a single video picture (or frame); each line for a given video field alternates with the line for the other field. In an interlaced picture half the lines are written on the screen in the first period of time, a sixtieth of a second for NTSC, and the second half are written in between the first during the second sixtieth of a second. A complete picture is completed in a thirtieth of a second.

See Cross-Color.

The process of assigning consecutive physical memory addresses alternately between two memory controllers in order to increase transfer rate.

In theatrical sound presentation, the means of running two systems in sync, such as a projector with a sound source. Interlock is used with the theatrical DTS Digital Sound system where a time code, read off of the film is used to synchronize the projection with the digital data being read from the CD-ROM unit.

Intermodulation Distortion (IM)
This refers to the generation of sum and difference tones in a waveform.

A feature of line doublers that corrects for time differences when each field traces 1/60 of a second after the preceding one, to minimize "jaggies" and preserve picture sharpness.

The Invar shadow mask in direct view TV sets is made up a brittle metal that is designed to allow higher picture contrast levels without incurring long-term damage to the shadow mask itself. It allows the set manufacturer to offer ever brighter contrast levels. In every case these higher contrast levels, requiring the Invar mask, push the phosphors well into blooming and cause a bleeding of colors. The high contrast levels permitted by the Invar mask will eventually burn the phosphors in the tube. In a properly adjusted TV set, the Invar shadow mask is not required. They are, in fact, a complete waste of money where a good picture is desired. The brittle metal is difficult to "drill," therefore the holes in he mask are not anywhere near as well formed as they would be in a conventional mask. This causes distortion in the picture, which is often hidden by the blooming of the high contrast levels. The high additional cost of this shadow mask material can only be justified by the ignorance of the consumer who doesn't know enough to keep the contrast level under control. If this so-called "premium feature" on so equipped sets were to be removed, real picture quality would go up, at a much smaller cost to the display device manufacturer.

Inverse Square Law
Any condition in which the magnitude of a physical quantity follows an inverse relationship to the square of the distance. In pure spherical divergence of sound from a point source in free space, the sound pressure level decreases 6 dB for each doubling of the distance.

(1) Infrared. Light/heat waves just below the visible spectrum; that is, waves slightly longer than those visible to the human eye. Filtered out to reduce heat on film or slides. (2) A type of wireless transmission standard using infrared light.

IRE Level
Institute of Radio Engineers' unit for expressing picture brightness in terms of the percentage of full brightness. 1 Volt peak-to-peak video is divided into 140 IRE units. This is done to make numbers for luminance levels easier to communicate. The amplitude of the video signal from blanking (zero volts) to peak white is 0.714286 volts or 100 IRE units. Synchronization signals extend from blanking to 1.285714 volts/ 40 IRE units.

IRE Scale
An oscilloscope scale that applies to composite video levels. Typically there are 140 IRE units in one volt (1 IRE = 7.14 mV).

Integrated Services Digital Network. An international communications standard for sending voice, video and data over digital telephone lines. ISDN uses special wires and can transfer at rates of 64,000 bits per second. Another version, called "B-ISDN" uses fiber optics and can transfer at 1.5 megabits per second.

The Imaging Science Foundation, Inc. An organization founded by Joe Kane and Joel Silver dedicated to promoting the awareness and importance of properly calibrating video systems to realize the full potential of NTSC video. ISF conducts special seminars to educate video and home theatre specialists on the essentials of adjusting monitors and televisions for proper performance.

ISO 2969
Frequency response standards for dubbing, screening, and commercial theatres, set in 1977. For playback of wide-range film audio soundtracks, curve "X" (the other being curve "N") is used. This frequency response specifies a gradual rolloff of 3 dB/octave at 2 kHz, extending to 16 kHz. The range from 50 Hz to 2 kHz is flat.

To separate airborne or mechanically transmitted energy. Khz/Kilohertz 1,000 Hz increments.