Tech Terms Glossary
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Headshell: A device for attaching the cartridge to the tone arm.
Hertz (Hz): Pronounced "hurts". Unit of measurement for cycles of vibration per second. Also kHz or kilohertz (1000 hertz) and MHz or megahertz (1 million hertz).
Horizontal (hum) Bars: Horizontal bars, alternately black and white, which extend over the entire picture. They are known as venetian-blinds. They may be stationary or move up or down. They are often caused by approximately 60 Hertz interfering frequency or its harmonic frequencies.
Horizontal Blanking: The blanking signal that is produced at the end of each scanning line.
Horizontal Resolution: The amount of detail a TV picture delivers, measured in number of lines. The amount a viewer actually sees depends both on the source and the TV: Broadcast or cable signals deliver 330 lines of horizontal resolution; VCRs, 240 to 280; laserdisc players, 425. The horizontal resolution capability of many TVs and other video monitors exceed any of these sources.
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ISDN (Integrated Services Digital Network): Digital phone lines that allow transmission of video signals via fastscan at speeds of 128Kb/second; used with terminal adapters.
Image Size: Reference to the size of an image formed by the lens onto the camera pickup device. The current standards are: 1", 2/3", 1/2" and 1/3" measured diagonally.
Impedance: The opposition which a circuit or component offers to the flow of electric current. It is expressed in ohms and is equal to the ratio of the effective value of the voltage applied to the circuit to the resulting current flow. In AC circuits, the impedance is a complex quantity that includes both resistance and reactance. In DC circuits, it is purely resistive.
Incident Light: The light that is falling directly over an object.
In-line: When one component is "inserted" into a circuit between other components.
Insertion Loss: The signal strength loss that occurs when a piece of equipment is inserted into a line.
Insulator: A protective coating used to inhibit conductivity between two conductive elements. Also, a shock absorber intended to prevent outside vibrations from exciting the turntable. Turntable cabinet feet are often constructed to act as insulators.
Integrated Circuit (IC): A complex collection of semiconductors in a single component case.
Interlace: A scanning process where every other horizontal line is scanned in one field while the alternate lines are scanned in the next field to produce a complete picture frame.
Interleaving: A method used in alarms or activity detection which allows extra frames of video from alarmed cameras to be added to a time multiplexed sequence whilst a state of alarm exists.
IR (infra-red): Literally means "below red". The band of frequencies just below the visible light spectrum.
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There are currently no terms defined in this section.
There are currently no terms defined in this section. |
