Reference Information, cont’d
Glossary of terms
Following is a list of terms taken from Extron’s Glossary.
AC – Alternating Current – Flow of electrons that changes direction alternately.
ADA – Extron’s product designation for Analog Distribution Amplifier.
AMPS – Amperes – A unit of measurement for current.
Analog – Analogue – A continuous signal that takes time to make a transition from one level to another. Standard audio and video signals are analog. This signal has an infinite number of levels between its highest and lowest value. (Not represented by bits, such as with digital.)
ANSI – American National Standards Institute
ASCII – American Standard Code for Information Interchange – The standard code consisting of
Attenuation – The decrease in magnitude of a signal.
Audio Follow – A term used when audio is tied to other signals, such as video, and they are switched together. (The opposite of
Balanced Audio – A method that uses three conductors for one audio signal. They are plus (+), minus
Bandwidth – A frequency range, or “band” of frequencies, within which a device operates. In audio and video, it is the band of frequencies that can pass through a device without significant loss or distortion. The higher the bandwidth, the sharper the picture; low bandwidth can cause a “fuzzy” picture.
Barrel – Outward curved edges on a display image. Also see “pincushion”.
Blanking – The turning off of the electron beam that scans the image onto the screen. When the beam completes a scan line it must return (retrace) back to the left. During this time, the beam must be turned off (horizontal blanking). Similarly, when the last line has been scanned at the bottom of the screen, the beam must return to the upper left. This requires vertical blanking.
Blooming – Most noticeable at the edges of images on a CRT, “blooming” is when the light (color) is so intense that it seems to exceed the boundary of the object. Thin lines and sharp edges could look thick and fuzzy. This may be caused by the brightness being set to high, or by a high voltage problem.
BNC – It is a cylindrical Bayonet Connector which operates with a
Buffer – Generally referred to as a unity gain amplifier used to isolate the signal source from the load. This is for both digital and analog signals.
Cable Equalization – The method of altering the frequency response of a video amplifier to compensate for high frequency losses in cables that it feeds. (See Peaking.)
Capacitance – The storing of an electrical charge. At high frequencies, capacitance that exists in cables also represents a form of impedance.
Cathode Ray Tube – See CRT.