Altinex Superstore - Altinex Term Glossary

Amplifier - A device or circuit that produces a larger power, voltage, or current at the output for a smaller power, voltage, or current at the input. Used generically to refer to a distribution amplifier or line driver.

Analog - A device or signal that represents data as a measurement of a continuous physical variable, such as a voltage. As compared with Digital.

Aspect Ratio - The relationship or ratio of the width of the picture to the height of the picture. For most current displays, this ratio is 4:3. For HDTV, the ratio is 16:9.

Bandwidth - Refers to both the range of frequencies that a device or circuit is capable of handling and the difference between the highest and lowest frequencies of a signal. In signal management, the bandwidth of a product that passes a video signal is of particular concern, especially when managing high resolution signals. Generally speaking, as the bandwidth specification of a product increases, the likelihood of degradation to the video image decreases. Please see Managing Your Signals in the Reference Section for a detailed discussion on this topic.

Buffer (Buffered Output) - In the PC lingo, a "buffer" is typically a temporary memory storage area. In signal management, however, the term "buffer" or "buffered output" refers to a type of output that is isolated from the input signal. That is, the loaded output does not affect the input, nor other outputs on the device. A buffered output may vary in terms of the gain or peaking adjustments made to the video signal; it does not specifically indicate that the output is amplified, though often this is the case. As compared with a Loop or Pass-through Output, which, when loaded, does affect the input and possibly other outputs.

Component Video - Unencoded video consisting of three signals that, together, transmit all necessary image information. Generally indicates a Y, R-Y, B-Y (Betacam™) signal format, but can refer to other formats, such as RGB or Y, Pr, Pb (HDTV). Component Video is used widely in broadcast and is sometimes preferred to Composite or S-video in a signal management system due to its higher level of quality and control.

Composite Sync - Video sync that combines both horizontal and vertical scan controls. Not long ago, Composite Sync (RGBS) was the primary sync format for passing computer video signals between a computer and a projector via an Interface. Now, RGBHV (with separate Horizontal Sync and Vertical Sync) is the predominant format.

Composite Video - A single video signal that contains all color, brightness, and timing information. Composite video is the preferred format for broadcast (non-computer) type video in a signal management system, in part due to the fact that it only requires one channel. NTSC, PAL, and SECAM are all composite video formats.

Display - Device for presenting computer video or broadcast video images. Includes monitors and projectors utilizing CRT, LCD, DLP, and Plasma technologies, among others.

Distribution Amplifier - A signal management solution that allows the connection of a single video or computer video source to multiple displays. Distribution Amplifiers are described by both the number of outputs they offer and their primary application (for example: 1-in 6-out VGA Distribution Amplifier). These devices are also often referred to as "Splitters." For more information on this subject, please see Selecting a Distribution Amplifier.

DVI – Digital Visual Interface. A digital computer video transmission standard developed by the Digital Display Working Group (DDWG), an industry consortium. A core component of the standard is the use of Silicon Image's PanelLink interface (also referred to as TMDS – Transition Minimized Differential Signaling). The DVI standard involves three sub-types, including an Analog-only version (DVI-A), a Digital-only version (DVI-D) and an Integrated Analog and Digital version (DVI-I). The term "DVI" is often used to describe the specialized 24-pin/29-pin interconnect used in the standard.

Frame Rate - The rate at which a frame of video is refreshed or re-drawn. For instance, with NTSC, the frame rate is 30 frames (60 fields) per second. For computer video, the frame rate can range from 60-100 frames per second. Typically, the higher the frame rate, the more stable and flicker-free the image is.

Frequency - The number of complete cycles per second existing in any form of wave motion, expressed as Hertz (Hz).

Gain - The amplification of a signal by a device, expressed in decibels. "Unity Gain" indicates 0 dB.

HDTV - High Definition Television. Includes several advanced standards proposals related to the transmission of high-resolution television designed for receiving in the home.

Hertz (Hz) - A unit of frequency equal to one cycle per second.

Impedance - Total opposition offered to the flow of an alternating current. Impedance may consist of any combination of resistance, inductive reactance, and capacitive reactance. Express in ohms.

Infrared (IR) Control - Wireless method of controlling signal management devices using electromagnetic radiation outside the visible spectrum.

Interface (Computer Video Interface) - A signal management solution that allows the connection of a computer video output to the input on a large screen monitor or projector. An Interface adapts the connector types between these devices, converts the signal format (e.g. RGBHV to RGBS) if necessary, buffers the signal, and provides a means of feeding a Local Monitor. An Interface also provides other features, such as the ability to adjust the horizontal positioning of the image on the screen. For more information on Interfaces, please see Selecting an Interface.

Matrix Switcher - A signal management solution that allows the routing of video, computer video and audio signals from multiple "sources" (computers, VCRs, etc.) to multiple "receiving devices." Once connected, any source can be routed to any destination, providing a full "matrix" of switching options. Matrix Switchers often lie at the heart of an audiovisual presentation system.

MHz - Megahertz. A million cycles per second.

NTSC - National Television Standards Committee or Never Twice the Same Color, depending on your perspective. Generically refers to the television video standard adopted in the U.S. in the 1950s and still used today. The NTSC standard involves a 525-line 60-field system. Also see PAL and SECAM.

PAL - Phase Alternate by Line or Picture Always Lousy, also depending on your perspective. A 625-line 50-field composite color video transmission system, adopted as a standard in England, Western Europe, South Africa, Australia, and other many other countries.

Plasma (Gas Plasma) - A flat panel display technology that makes use of gas in a plasma state controlled by electronics to produce sharp color images. Typically used for large screen displays with shallow depth, often in a 16:9 (widescreen) format.

Plenum – Refers to the airspace between a ceiling and the roof or next level of a building. In signal management, Plenum-rated cable is designed for fire and heat resistance, allowing it to be used (in most cases) in plenum airspace without need for conduit. A plenum-rated cable must meet specific UL requirements.

Refresh Rate - The rate, expressed in Hertz, at which a display "refreshes" or redraws a field or frame of the video image. Generally, the higher the refresh rate, the less flicker and more stable the image is. Also called Vertical Frequency.

Resolution - A basic measurement of how much information is presented on a display, described by the number of pixels in a line and the number of lines per frame. VGA has a resolution of 640x480, SVGA a resolution of 800x600, and XGA a resolution of 1024x768. The higher the resolution, the sharper the picture. For a more complete understanding of a video resolution, the Refresh Rate should also be considered (e.g. 1024x768 at 70Hz).

RF - Radio Frequency

RGBS - Red, Green, Blue, (Composite) Sync

RGBHV - Red, Green, Blue, Horizontal Sync, Vertical Sync

RGsB - Red, Green with (Composite) Sync, Blue

RS-232 - A communications interface standard used widely in controlling devices in a signal management system.

S-video - Also referred to as "Y/C" wherein Y stands for Luma and C stands for Chroma. S-video makes use of a two channel signal processing system, resulting in better resolution and less noise than standard composite video.

Scan Doubler – A device that converts an interlaced composite or S-video signal to a higher-resolution non-interlaced signal. With composite video, a display requires two interlaced fields of video to make up a single frame, while the output from this device draws a complete frame with a single pass, thus the term "doubler."

Scan Reducer – A device that converts high-resolution computer video signals to lower resolution broadcast-type video signals for the purpose of recording program material or for display on a lower resolution display. Also called a Scan Converter, this device typically accepts a non-interlaced or progressive RGB format signal and outputs an interlaced composite or S-video type signal.

Signal-to-Noise Ratio (S/N Ratio) - The magnitude of the signal divided by the noise interfering with the signal, expressed in decibels. The higher the Signal-to-Noise ratio specification, the better.

SVGA -Super Video Graphics Array. An extension of the VGA standard.

Switcher - A signal management solution that allows the connection of multiple "sources" (computer video, video, and audio) to a single display or other "receiving" device, such as a sound reinforcement system or a VCR. Switchers are described by both the application they are used for and the number of inputs they offer; for example, a VGA 6-in 1-out Switcher. Most relay type switchers can also be used backwards, allowing them to switch multiple sources to a single display.

Sync - The portion of a video signal that instructs the display on where and when to place video information. Sync is comprised of both horizontal information (Horizontal Sync) and vertical information (Vertical Sync). Lack of sync causes a complete lack of picture. Lack of one-half of the sync (i.e. H-Sync or V-Sync) causes the picture to roll rapidly. Poor quality sync can cause a variety of image problems, including bending and jitter.

Sync Delay™ - An innovative switching feature pioneered by ALTINEX that enables glitch-free switching between high resolution computer video sources. When this feature is activated on a Switcher that offers it, the video portion of an incoming image is delayed while the sync locks up, making the glitch take place off screen. In other words, the screen goes blank momentarily and then returns with a "locked" video image.

Vertical Scan Rate - The speed at which a video source redraws a new frame or field of a screen. In NTSC, the screen is completely redrawn once every 30th of a second. Computer video scan rates vary, though they usually range from 60-100 frames per second. Expressed in hertz (Hz). See Horizontal Scan Rate.

Vertical Sync (V. Sync) - The portion of a video signal that instructs where information should be displayed in a top to bottom dimension. Lack of Vertical Sync causes an image to roll rapidly in a horizontal motion. Also see Horizontal Sync (H-Sync).

VGA - Video Graphics Array. Refers specifically to a computer video standard specifying a 640x480 resolution. However, this term is used widely to describe many different things. For instance, a "VGA cable" refers to a multi-channel cable with 15-pin HD type connectors on either side, designed to interconnect a VGA-type source to a VGA-type display. It is also used as a generic way to describe other standards, such as SVGA, XGA, UXGA, etc. When this term is used, it is wise to always clarify the topic of discussion to avoid confusion.

Y/C - Y stands for Luma, C stands for Chroma. Used as a way to describe two-channel S-video (S-VHS) type signals.

Y, R-Y, B-Y - Component analog video signal format. Y represents luma, R-Y represents the first color difference signal, and B-Y represents the second color difference signal. When R-Y (red-minus-luma) is added to Y (luma), the red primary signal is produced. When B-Y (blue-minus-luma) is added to Y (luma) the blue primary signal is produced.