Glossary

A/D - Analog to Digital (converter). A device that converts an analog signal to a digital value.

 

AACS – Advanced Access Content System - A digital rights management standard utilized with Blu-ray Disc and other optical formats. AACS incorporates two parts: a set of embedded decryption keys within the source device, and a set of keys encoded in the content that describes each of the playback devices licensed to utilize the content. This approach allows copyright holders to revoke the keys of a particular source device, thus preventing it from playing back future content. AACS also provides for a managed copy system, that is, a mechanism by which one or several, but not an unlimited number of copies can be legally made as backups, for storage on a media server, or for use on a portable device. The ICT – Image Constraint Token is a provision within AACS that allows the content provider to limit analog output resolutions.

Back porch - The time in a composite video signal that is between the trailing edge of the sync pulse and the trailing edge of the blanking pulse (before the video information).

 

Backbone - The primary transmission network for telecommunications that connects between key locations and branches off to buildings and other facilities.

 

Cable equalization - The method of altering the frequency response of a video amplifier to compensate for high frequency loss in cables that it feeds.

 

D connector - A connector with rounded corners and angled ends, taking on the shape of the letter D. Commonly used in computers and video, most D connectors have two rows of pins. If they have more than two rows, they are usually called HD (High Density) connectors.

 

Echo cancellation - A DSP technique that filters unwanted signals caused by echoes from the main audio source.

 

Fan-Out Kit - In fiber optics, a kit designed for use with loose tube cable with bare fiber bundles in each buffer tube. The kit enables termination as well as protection of these bare fibers.

 

Z - A symbol for impedance.

Zipcord - A cable comprising two jacketed wires or optical fibers that are conjoined together and can be separated.

 

Y signal - The luma signal transmitted in standard color video. In a color picture, the Y signal is made up of 0.30 red, 0.59 green, and 0.11 blue. It is compatible with a standard monochrome receiver.

 

Y to C delay - Relative delay or timing of the luminance channel compared to the chrominance channel in a video system.

Waveform - A display of a signal (on an oscilloscope) that shows the magnitude of current or voltage signals with respect to time. By displaying the waveform of a signal on an oscilloscope, the time between cycles can be measured and its frequency can be calculated.
 

Waveform monitor - A special oscilloscope used to display and analyze electrical (voltage or current) signals.

Waveguide - An acoustic device built into a loudspeaker enclosure that improves the efficiency of the speaker by confining the movement of a sound wave to travel over a desired path. In brief, a waveguide is a tube-like structure, straight or folded, that couples the motion of the loudspeaker cone to the motion of the air in the tube. This allows a small speaker driver to create clear sound, without distortion, even at the high volume levels required for low frequency reproduction.

Waveguide Dispersion - The distortion of an electromagnetic signal, or in the case of fiber optics, light as it encounters a waveguide and is dispersed into multiple components of different modes or wavelengths.

Wavelength - The distance from one peak to the next between identical points in adjacent waves of electromagnetic signals propagated in space or along a wire. Wavelength is usually specified in meters, centimeters, or millimeters. In the case of infrared, visible light, ultraviolet, and gamma radiation, the wavelength is usually specified in nanometers (10e-9 meter) or Angstroms (10e-10 meter). Wavelength is inversely related to frequency. The higher the frequency of the signal, the shorter the wavelength.

Wavelength Division Multiplexing – WDM - The combination of two or more optical signals at different wavelengths for transmission within a single optical fiber.

Weighting filter - A special type of band-limiting filter used in measuring audio loudness levels that “weights”, or gives more attention to, certain frequency bands. Common weighting filter designs include: A-weighting, a wide bandpass filter, centered at 2.5 kHz, that mimics the way we hear (see “Fletcher-Munson Curve”); and C-weighting, generally “flat” frequency response with -3 dB attenuation at 31.5 Hz and 8 kHz.

White - The lightest visible surface created by a reflection of all colored light.

White level - In television, the signal level that corresponds to the maximum picture brightness. The white level is set by the contrast control.

White light - A blend of multiple colors of the visible portion of electromagnetic spectrum, resulting in light that is white in color to the human eye.

White noise - Noise with random amplitude (strength) over a wide frequency range. Used to test speakers for resonance and sensitivity. Low levels of white noise can be used to cover up other random noises, for example, in an open office environment.

Wideband - A relative term indicating a high bandwidth.

Wipe - A visual transition between images during which the edge of one image moves across the screen revealing the next image.

WLAN - Wireless Local Area Network. A form of local area network that uses radio waves to transmit data between nodes rather than through cable. Mobile devices, such as laptop computers and personal digital assistants, have helped spawn the “plugless” connection to WLANs. The IEEE 802.11 standard specifies the technologies for wireless LANs.

Woofer - A loudspeaker designed to reproduce low frequencies.

Workstation - A type of computer used in design or development work, such as engineering and CAD, requiring a moderate amount of computing power and high-resolution graphics.

Wow - A low pitch audio artifact caused by speed fluctuation in the playback device. Also see "Flutter."

Wrap-around - A video problem that occurs when the left picture information is displayed on the right side of the screen and the right picture information is displayed on the left side of the screen, separated by a vertical bar.

WSXGA - “Wide-SXGA” defines a class of SXGA displays with a width resolution sufficient to create an aspect ratio of 16:9. Resolution is defined as the number of individual dots that a display uses to create an image. These dots are called pixels. A WSXGA display has 1920 to 1600 horizontal pixels and 1080 to 900 vertical pixels respectively that are used to compose the image delivered by the projector.