Technical Glossary
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Displaying 48 glossary terms found.


H Or H/V
Horizontal (H) sync, or horizontal and vertical sync combined (H/V). On connector panels, H identifies the connector for horizontal sync and H/V means it is also used for combined, or "composite" horizontal and vertical sync.

Haas Effect
Also called the Precedence Effect. Delayed sounds are integrated if they fall on the ear within 20 to 40 msec of the direct sound. The level of the delayed components contributes to the apparent level of the sound.

A term used in communications that refers to the activity that takes place when the transmitting and receiving devices identify themselves, each to the other.

The physical equipment required for a particular function in a particular medium.

Harmonic Distortion
The production of harmonics or overtones which do not exist in the original waveform. An unwanted alteration of an audio signal in which multiples of the original frequencies are added. Hanging Dots - Picture distortion created when picture information falls between scanning lines or fields resulting in a line of stationary dots along the horizontal edges of sharp color transitions. Stationary dot crawl. See Dot Crawl.

Harmonic Distortion
Distortion that occurs when an audio component adds unwanted overtones to the original music tones.

In music, Overtones. Multiples of an original frequency that add to, and modify, the original frequency. A pure sine wave is free of harmonics. In music, it is what makes one instrument sound different from another while playing the same note. In music, this is usually a desirable effect, however, when harmonics occur in audio or video, it adds distortion to the original signal, causing undesirable results.

High Definition. See HDTV.

HD Connector
A high-density "D" connector having its pins arranged in three rows. A normal D connector has its pins arranged in two rows. Example: VGA connector.

High Definition TeleVision. The Consumer Electronics Manufacturers Association (CEMA) standardized definition is a complete product/system with the following minimum performance attributes: Resolution: Vertical scanning line display resolution of 720P (Progressive), 1080I (Interlace), or higher. Aspect Ratio: Capable of displaying a 16:9 (1.78:1) image at the minimum resolution level. Audio: Receives, reproduces, and/or outputs Dolby(r) Digital audio (mono, stereo, matrix stereo or discrete 5.1-channel). Receiver: Receives all 18 ATSC Table III formats. See Grand Alliance, ATSC, DTV (Digital TeleVision), and SDTV (Standard Definition TeleVision).

The capacity of a device above its normal operating level in which it can permit peaks to pass undistorted. The margin of safety for an audio component between the highest audio signal levels produced and the maximum level that can be achieved without distortion. Expressed in dB

Helmholtz Resonator
A reactive, tuned, sound absorber. A bottle is such a resonator. It can employ a perforated cover or slats over a cavity.

Hz. The measuring unit of frequency or the speed of vibration of a sound wave. Synonymous with "cycles per second" (CPS).The unit of frequency equal to one cycle per second. One kilohertz (kHz) equals 1,000 cps; one megahertz (MHz) equals one million cps.

Hertz System
50 Hz. A system for automatically advancing visual materials, usually filmstrips, by a 50 Hz signal on the audio program, according to ANSI standard PH7.4. In playback, the audio is divided by filters, allowing the program material to pass through in a normal manner, while the 50 Hz audio cues advance the visual.

A high band videotape format by Sony using 8mm tape. High quality and compact, Hi-8 is being marketed for ENG (Electronic News Gathering).

Term for High Fidelity. Also High Fidelity stereo recording system with matrix surround capability for home VCRs.

High Band
A recording method in which the carrier frequency is shifted higher, in order to get high resolution.

High Fidelity
Hi Fi, Accurate and faithful reproduction of the original. Absence of distortion or enhancements.

High Frequency
In audio, the range rom about 5 kHz to 20 kHz.

High Impedance
Hi Z or High Z. A relative term that is different for each application. In video, when the signal is not terminated it is said to have a Hi Z load. Hi Z is typically 800-10k ohms or greater.

High Resolution
A camera or monitor with 1000-2000 scanning lines. Produces a sharp, detailed image.

High Voltage (HV) Power Supply
The High Voltage (HV) Power Supply supplies the life-blood that enables the Cathode Ray Tube (CRT) to generate and maintain an accurately calibrated picture. It plays a critical role in monitor performance by supplying the multiplicity of voltages required to operate the CRT electron gun. It is the responsibility of the HV supply to provide the electron gun beam current and the CRT anode voltage that accelerates the electrons toward the screen. It also provides voltages to other electron gun elements that focus the electrons into a beam to provide the smallest possible spot size at the screen. The beam current is continuously changing to create the different luminance levels within the picture. The HV supply must generate the correct voltages and hold them constant, even when the beam current changes.

High-Pass Filter
A filter circuit, as in a loudspeaker crossover network, which allows only frequencies higher than a specified frequency to pass through unaltered; lower frequencies are attenuated or rolled-off.

Noise that sounds like prolonged sibilant sounds. This can occur from bad cassette tape, vinyl albums, live snakes, etc.

A descriptive term that expresses the sense of a three-dimensional "real" spatial experience created by a multichannel discrete soundtrack. See Soundfield.

Home Automation
A unified control system in which electric and electronic products can communicate with one another via power lines, twisted (telephone) pairs, coaxial cable, RF and/or infrared means. "Bridge" devices convert signals from one carrier to another to enable data transmission. See CEBus(r).

Home Theatre / Home Theater
An ensemble of home audio and video components with the objective of recreating the theatrical experience of sound and picture. Home theatre generally consists of a video display device (size 27-inch or greater), a video source (LaserDisc, DVD or Hi-Fi VCR), and a surround-sound system with Dolby ProLogic, Dolby Digital, or DTS Digital Surround decoding. Theatre is often spelled with "er" instead of the traditional motion picture industry spelling with "re."

Home THX®
Lucasfilm's consumer version of THX for home theatre equipment. See THX.

Uniform in structure and composition.

Horizontal Blanking
Retrace. The process of bringing the electron beam in a CRT back to the left side of the screen after a left to right line has been traced on the screen. The beam is shut off, blanked, during the period of retrace. About 83 percent of the total horizontal line time is spent writing the line. The remaining 17 percent is spent bringing the beam back to the left side; retrace, before starting the next time.

Horizontal Dispersion
The dispersion of a loudspeaker in he horizontal plane. See Vertical Dispersion.

Horizontal Picture Centering Control
Adjusting the horizontal picture centering control one way shifts the displayed image toward the left of the monitor or projector screen and the other way shifts the displayed image to the right of the monitor or projector screen.

Horizontal Resolution
The most commonly quoted specification for fine detail picture quality is horizontal resolution,.measured in lines. It is partially determined by the frequency response capability of the video signal. It is traditionally specified as the number of transitions in the horizontal direction per picture height. It is represented in the picture by the number of vertical lines that can be perceived in a video device horizontally from one side of the screen to the other-specified as the number of transitions that can occur in the horizontal direction. If you were to put up a test pattern testing horizontal resolution, it would consist of vertical lines. The more lines that can be displayed, the better the picture. Horizontal resolution is measured in terms of the picture height. A standard broadcast television signal is limited to 330 lines of horizontal resolution per picture height, while the DVD is as high as 480, LaserDisc as high as 425, and VHS as low as 240 lines. Horizontal resolution in a computer system is specified for the entire width of the screen instead of to the point equal in distance to the picture height. A 480 line horizontal resolution per picture height in the television system becomes 640 lines across the entire screen. Many people are under the impression that line doubling will double the claimed lines of resolution. A line doubler does not increase horizontal resolution. The spatial representation on the screen remains the same in a doubler or quadrupler even though the frequency increases. That's because along with the frequency increase there is also a scan rate increase. In a doubler, as an example, both the frequency on the line and the line rate doubles, therefore, the spatial representation on the screen remains the same. See Luminance Picture Resolution.

Horizontal Scan Rate
Horizontal frequency. The number of complete horizontal lines, including trace and retrace, scanned per second. Typically shown as a measure of kHz. The number indicates the rate at which the electron beam moves across the CRT horizontally. The rate is the process of drawing a video line on the screen. Video-grade projectors have a fixed scan rate of 15.75 kHz, which limits their use to standard NTSC video. Line doublers will increase the scan rate to 31 kHz or so. See Vertical Scan Rate.

Horizontal Sync
The sync pulses that control the horizontal scanning of the electron beam in a video device. NTSC standard is 15.75 kHz.

Horizontal Viewing Angle (In Degrees)
The figure listed is the maximum number of degrees radiating from the center of the screen, from which a clear picture still can be seen from the side of the set.

A loudspeaker in which the coil is attached to a metal diaphragm which excites the air in front of it, this is attached to the horn itself. Horns are more efficient than moving-coil units and deal with the middle and upper frequencies.

Hot Spot
Commonly seen on high-gain screens, and screens designed for slide or movie projection, a circular area where the image is brighter than the rest of the screen. The hot spot always appears located along the line of sight, and "moves" with the line of sight.

The ability to change electronic components, such as circuit boards or peripheral devices without removing power.

High Quality. Picture-enhancement circuits in VHS VCRs that have the White Clip Level circuit and one or more of the other three circuits: Detail Enhancer, Luminance Signal Noise Reduction, and Chrominance Signal Reduction.

In color graphics, Hue-Saturation-Brightness. (Hue = the color, Saturation = the amount of color, and Brightness = the amount of white).

Horizontal Sync Signal. Signal derived from composite video signal.

Tint control. Hue is the shade parameter of color values that allows us to distinguish between colors. The hue, or tint control adjusts the amount of color displayed, based on the phase of the chrominance signal. Continuously varying the hue control results in colors spanning a spectrum from red to green to blue. See HSB.

The coupling of an unwanted frequency into other electrical signals. In audio, a "hum" can be heard; in video, it can appear as waves in the picture. Often it is an audible disturbance caused by the power supply.

Hum Bar
Interference in the form of a horizontal bar moving vertically on the television screen. Can be caused by ground loops.

A transformer used to isolate video signals cause by interference from hum bars or moiré.

Designation for composite horizontal and vertical (combined) sync. For separate sync, the two letters are used separately (H and V).

Hertz. The international electrical term for frequency in cycles per second.