Glossary of Terms

Appendix B • Reference and Glossary

For a complete glossary, see Extron’s web site (http://www.extron.com)

AC –

Alternating current. The flow of electrons that changes direction alternately.

AC reset –

The status that changes when power is removed from a device. Many electronic devices have live power inside, even after “power off” has been initiated from a panel or remote control device. This is not the same as “AC reset”, when power is removed at the AC cord.

Amp –

Ampere. The international base unit of electric current. Symbolized by “A”. 1 amp is equal to the steady current produced by 1 volt applied across a resistance of 1 ohm.

Analog –

A continuous action or movement that takes time to make a transition from one level to another. Standard audio and video signals are analog. An analog signal has an infinite number of levels between its highest and lowest value. (Changes are not made by steps, such as with digital.)

ANSI –

American National Standards Institute. The organization that sets standards for

US A/V equipment.

ASCII –

American Standard Code for Information Interchange. 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.

Attenuation –

To reduce the amplitude (strength) of a signal or current.

Audio follow –

A term used when an audio signal is tied to the video signal and they are switched together; the opposite of breakaway.

Balanced audio –

Audio circuits that use three conductors for one audio signal: plus (+), minus (-) and ground. The ground conductor is strictly for shielding, and does not carry any signal. Also called differential audio.

Bandwidth –

A frequency range, or “band” of frequencies, between the limits defined by the “half power points”, where the signal loss is -3dB. In audio and video, it is this band of frequencies that can pass through a device without significant loss or distortion. The wider the bandwidth, the better the quality that results, such as a sharper picture, better sound, etc. The higher the bandwidth number, the better the performance. (300 MHz is better than 250 MHz.) When a signal passes through a path with more than one device (including cables), the limiting factor (bottleneck) in that path is the device with the narrowest bandwidth.

Blooming –

Most noticeable at the edges of images on a CRT, “blooming” is when the light hitting the screen is too intense and overdrives the phosphors. The edges of an image seem to exceed its boundaries. Thin lines and sharp edges may look thick and fuzzy. This may be caused by the brightness being set too high, or by a high voltage problem.

BNC –

A cylindrical bayonet connector that operates with a twist-locking motion. Two curved grooves in the collar of the male connector are aligned with two projections on the outside of the female collar. This allows the connector to be locked in place without tools.

Breakaway –

The ability to separate video and audio signals for the purpose of switching them independently. For example, an audio and video signal from the same source may be “broken away” and switched to different destinations. This is the opposite of audio follow.

Buffer –

Generally referred to as a unity gain amplifier, a buffer is used to isolate the signal source from the load. A buffer can be used for digital or analog signals. The RGB 322, 324, 326 and 340 are input buffers to the RGB 320 switching interface.

Extron • User’s Manual • RGB 320 Switching Interface System

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