Videoscope - Services

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24P - 24 frames per second, progressive scan. Standard motion picture frame rate. Now common in TV High Definition production, usually with 1080 lines, progressive scan.

24PsF - 24 frames per second, each frame segmented, recorded as odd lines, even lines. More compatible with video. Plays without 24 frame flicker.

25P- 25 frames per second, progressive scan. PAL frame rate, standard in Europe

3.58mhz - The approximate frequency of the sub-carrier used in NTSC video to carry the color information. The actual frequency is 3.579545Mhz ą 10Hz.

4.43mhz -The approximate frequency of the sub-carrier used in PAL video to carry the color information. The actual frequency is 4.43361875 ą 5Hz.

4:2:2 - A commonly-used term for a component digital video format. The details of the format are specified in the CCIR601 standard document. The numerals 4:2:2 denote the approximate ratio of the sampling frequencies of the single luminance channel to the two color channels. For every four luminance samples, there are two samples of each color channel.

4:4:4 - A high end digital video format. For every four luminance samples, there are four samples of each color channel.

5.1 Audio - Dolby Surround Sound

8281 - A commonly-used type of precision, double-shielded, 75-ohm video cable manufactured by Belden Wire & Cable Company.

A-B Roll - Videotape editing arrangement where scenes on tape are played alternately on VTRs A and B and recorded on VTR C. Typically, the final output recorded on VTR C contains some scenes from VTR A and some scenes from VTR B with transitions (cuts, mixes, wipes etc.) between the scenes.

AGC (Automatic Gain Control) - Automatic gain can be applied ahead of almost any circuit that requires specific levels to operate. As an example, the color decoder needs to see a particular level of color sub-carrier at its input in order to display the correct color at the output. There is a reference burst, at the beginning of each horizontal line of known amplitude. The AGC circuit looks at the incoming signal level and applies any gain correction necessary to make the burst amplitude correct. In the process of doing that, it also corrects the amplitude of the color information in the active picture area.

Amplitude - The magnitude of a signal in voltage or current. Frequently expressed in terms of peak, peak-to-peak, or RMS.

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.)

Analog Component - Another name for component video, such as RGB or Y, R-Y, B-Y, as opposed to digital component video. See component video.

ANSI - American National Standards Institute.

APL - Average Picture Level. The average signal level (with respect to blanking) during active picture time, expressed as a percentage of the difference between the blanking and reference white levels.

Artifacts - Undesirable elements or defects in a video picture. These may occur naturally in the video process and must be eliminated in order to achieve a high-quality picture. Most common are cross color and cross luminance.

Aspect Ratio - Horizontal dimensions of a picture expressed relative to the vertical dimensions. The aspect ratio of all broadcast composite video systems is 4 units wide by 3 units high.

Assemble Edit (assemble mode) - An editing mode that replaces all signals on the record tape (video, audio, control, and time code tracks) with new signals. See also insert edit.

Asynchronous - Lacking synchronization. In video, a signal is asynchronous when its timing differs from that of the system reference signal. A foreign video signal is asynchronous before it is treated by a local frame synchronizer.

Attenuation - The decrease in amplitude of a signal.

Auto-Termination - In equipment that has loop-thru, or "daisy-chain" connections, termination is done at the last device on the chain. Some such devices provide termination automatically by the fact that there is no cable going out. Thus this is the last device and termination is provided.

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.)

Background Generator - A video generator that produces a solid-color output which can be adjusted for hue, chroma, and luminance.

Balanced Audio - A method that uses three conductors for one audio signal. They are plus (+), minus (-) and ground. The ground conductor is strictly for shielding, and does not carry any signal. Also Differential Audio.

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 "fussy" picture.

Baud - A unit of signaling speed equal to the number of signal events per second. Baud is equivalent to bits per second in cases where each signal event represents exactly one bit. Often the term baud rate is used informally to mean baud, referring to the specified maximum rate of data transmission along an interconnection. Typically the baud settings of two devices must match if the devices are to communicate with one another.

Betacam - Portable camera/recorder system using 1/2-inch tape originally developed by Sony. The name may also refer just to the recorder or the interconnect format; Betacam uses a version of the Y, R-Y, B-Y color difference signal set. Betacam is a registered trademark of the Sony Corporation.

Betacam SP - A superior performance version of Betacam. SP uses metal particle tape and a wider bandwidth recording system.

Black Level - See Set-up

Black & White - Monochrome or luminance information. Monochrome means one color. In the color television system the Black & White portion of the picture has to be one "color"; gray, D6500, 6500K as defined by x and y values in the 1939 CIE color coordinate system.

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.

Blanking Level - It is the level of a video signal which separates the range that contains the picture information from the range that contains the sync information. The level of the front and back porches. Zero IEEE units.

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 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 the need of tools.

Breezeway - The early part of the Back Porch portion of the video signal. The area between the horizontal sync pulse and the color burst.

Brightness Ratio - The difference between the brightest and darkest object in a picture. Too much of a difference can cause unacceptable contrast.

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.

Burst - See Color Burst.

B-Y - One of the color difference signals used in the NTSC system, obtained by subtracting luminance from the blue video signal. This is the signal which drives the horizontal axis of a vectorscope.

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

Camera Control Unit (CCU) - A separate electronics frame connected to a video camera head to supply it with power and control. The CCU also provides encoding and/or processing of the video signal. Operator controls available at the CCU usually include video levels, color balancing, and iris control.

Capacitance - The storing of an electrical charge. At high frequencies, capacitance that exists in cables also represents a form of impedance.

CAV (Component Analog Video) - Component video signals in which an analog voltage or current represents the value of the pixel, the same as "analog components."

CCD - Abbreviation of charge coupled device. A device that stores samples of analog signals. Used in cameras and telecines as an optical scanning mechanism. Advantages include good sensitivity in low light and absence of burn-in and phosphor lag found in CRTs.

CD-ROM - Compact Disc-Read Only Memory. A 4.75-inch laser-encoded optical memory storage medium with the same constant linear velocity (CLV) spiral format as compact audio discs and some videodiscs.

CD-ROM XA - Compact Disc-Read Only Memory Extended Architecture. An extension of the CD-ROM standard billed as a hybrid of CD-ROM and CD-I, and promoted by Sony and Microsoft. The extension adds ADPCM audio to permit the interleaving of sound and video data to animation, with sound synchronization.

Chroma - The characteristics of color information, independent of luminance intensity. Hue and saturation are qualities of chroma. Black, gray, and white objects do not have chroma characteristics.

Chroma Key (Color Key) - A video key effect in which one video signal is inserted in place of areas of a particular color in another video signal. For example, a weatherman stands in front of a blue wall with a camera focused on him. The camera signal feeds a chroma keyer which detects the blue in the blue wall and replaces it with video from another camera, such as video of a weather map. The finished key makes the weatherman appear to be standing in front of the map.

Chrominance Signal - Part of a color television signal containing the color information Abbreviated by "C".

Clamp, clamping - The circuit or process that restores the DC component of a signal. A video clamp circuit, usually triggered by horizontal synchronizing pulses, re-establishes a fixed dc reference level for the video signal. Some clamp circuits clamp sync tip to a fixed level, and others clamp back porch (blanking) to a fixed level. A major benefit of a clamp is the removal of low-frequency interference, especially power line hum.

Clipping - The process of shearing off the peaks (or excursions) of a signal.

Coaxial Cable - A two-conductor wire in which one conductor completely wraps the other, with the two separated by insulation. Constant impedance transmission cable.

Color Bar - A test pattern containing six basic colors: yellow, cyan, green, magenta, red, and blue - used to check the chrominance functions of color TV systems.

Color Burst - In color systems, a burst of sub-carrier frequency located on the back porch of the composite video signal. This serves as a color synchronizing signal to establish a frequency and phase reference for the chrominance signal.

Color Difference Signals - Signals used by color television systems to convey color information in such a way that the signals go to zero when there is no color in the picture. R-Y, B-Y, I and Q are all color difference signals.

Color Phase (Hue) - The correct timing relationship within a color display. Color is considered to be in phase when the hue is reproduced correctly.

Color Sub-Carrier - A 3.58 MHz signal interwoven with a standard NTSC monochrome signal that contains color information.

Comb Filter - So called because of the shape of its frequency response, the Comb Filter provides a better method of separating Y and C than a chroma bandpass or chroma trap. Therefore it produces better quality video, (less crawling, or "zipper" artifacts.)

Component - (Video Signal) The fundamental electrical signal for producing video images. Three of these signals are needed for color video and the term component is used to indicate one considered alone. The signals may be in digital or analog form. They may be in the combination of Red, Green and Blue or they may be in some other form such as luminance, R-Y, and B-Y. In general, the RGB signals can be arithmetically combined into any three components and decoded at the display device into the RGB components necessary to make the color picture.

Component Video - Our color television system starts with three channels of information; Red, Green, and Blue (RGB). In the process of translating these channels to a single composite video signal they are often first converted to Y, R-Y, and B-Y. Both 3-channel systems, RGB and Y, R-Y, B-Y are component video signals. They are the components that eventually make up the composite video signal. Much higher program production quality is possible if the elements are assembled in the component domain.

Composite Sync - A signal consisting of horizontal sync pulses, vertical sync pulses, and equalizing pulses only, with no signal reference level.

Composite Video - A mixed signal comprised of the luminance black and white, chrominance (color), blanking pulses, sync pulses and color burst.

Computer-Video Interface - A device which converts the "nonstandard" video output of computer systems to a "standard" RGB analog signal that can then be connected to a compatible data monitor or projector.

Contrast - The range of light and dark values in a picture or the ratio between the maximum and the minimum brightness values. Low contrast is shown mainly as shades of gray, white high contrast is shown as blacks and whites with very little gray. It is also a TV monitor adjustment which increases or decreases the level of contrast of a televised picture.

Contrast Ratio - This is the ratio of the highlight output level divided by the low light output level. In theory, the contrast ratio of the television system should be at least 100:1, if not 300:1. In reality there are several limitations. In the CRT itself, light from adjacent elements contaminate the area of each element. Room ambient light will contaminate the light emitted from the CRT. Well controlled viewing conditions should yield a practical ratio of 30:1 to 50:1.

Convergence - The alignment of the Red, Green and Blue video on a projected display.

CRT(Cathode Ray Tube) - A vacuum tube that produces light when energized by the electron beam generated inside the tube. A CRT has a heater element, cathode, and grids in the neck of the tube, making up the "gun". An electron beam is produced by the gun and is accelerated toward the front display, or screen surface of the tube. The display surface contains phosphors that light up when hit by the electron beam. The CRT is more commonly known as picture tube.

D1 - A component digital videotape recording format that conforms to the specifications set in the CCIR 601 standard.

D2 - An 8-bit composite digital videotape recording format in which the composite video signal is digitized by sampling it at the rate of four times the frequency of sub-carrier (4fsc). The 4fsc frequency in NTSC is 14.3 MHz and 17.7 MHz in PAL.

D3 - An unofficial term for a composite digital videotape recording format invented by Panasonic.

DA - Abbreviation of distribution amplifier.

DAT (Digital Audio Tape) - A method of recording digital audio information on tape at a high density and high quality. The method uses a rotating head, similar to that used in video tape recording.

Data Monitor - A monitor with horizontal scan capability between 15.75-36 (42) kHz. Data monitors and projectors are commonly associated with NTSC video, IBM CGA through VGA and Apple/Macintosh computer input sources.

dB (Decibel) - The standard unit used to express gain or loss of power. It indicates the logarithmic ratio of output power divided by input power. A power loss of 3 dB is an attenuation of half of the original value. The term "3dB down" is to describe the "half power point".

DC (Direct Current) - The flow of electrons in one direction.

DC Restoration - The correct blanking level far a video signal is zero volts. When a video signal is AC-coupled between stages, it loses its DC reference. A DC Restoration circuit clamps the blanking at a fixed level. If set properly, this level is zero volts.

Decoder - A device used to separate the RGBS (Red, Green, Blue and Sync) signals from a composite video signal (90IQ).

Degauss - 1. To demagnetize (erase) all recorded material on a magnetic medium, such as video or audio tape. 2. To demagnetize the shadow mask in a color picture tube.

Diagnostics - A program built into a device which tests the functionality of the device and reports the results. Used as an aid in troubleshooting.

Differential Gain - A change in sub-carrier amplitude of a video signal caused by a change in luminance level of the signal. The resulting TV picture will show a change in color saturation caused by a simultaneous change in picture brightness.

Digital Signal - Digital signals have two levels: high/low or on/off. AKA: TTL.

Distribution Amplifier (DA) - A device that allows connections of one input source to multiple output sources as monitors or projectors.

Dot Pitch - The distance between the sets holes or slots (Trinitron system) for the colors on the adjacent line of a CRT monitor shadow mask. A smaller the dot pitch allows for more potential dots to be displayed, thus achieving better resolution (see Shadow Mask).

Downstream - Occurring after other devices in a signal path.

Downstream Keyer - A keyer that inserts the key after the effects system video output. This enables the key to remain on-air while the backgrounds and effects keys are changed behind it.

Drop-Frame Time Code - SMPTE time code format that continuously counts 30 frames per second but drops 2 frames from the count every minute except for every tenth minute (drops 108 frames every hour) to maintain synchronization of time code with clock time. This is necessary because the actual frame rate of NTSC video is 29.94 frames per second rather than an even 30 frames. See Non-Drop Frame Time Code.

Dropout - A Momentary loss or deterioration of video or audio during playback on a tape machine. Caused by momentary loss of tape contact with the playback head or by flaws in the tape.

DVE - Abbreviation of digital video effects. A registered trademark of Nippon Electronics Company.

ECL - Emitter Coupled Logic. ECL signals are high speed digital logic and are mostly found in high resolution CAD/CAM computers and are usually monochrome or black and white. ECL operates in two level states and switches between these states in small increments of time. Bits are: Next/Most/Least Significant. Conversion to analog is required for proper interfacing.

Edit Decision List (EDL) - A list of edit decisions accumulated in a video editor. The list typically includes the source, in time, and out time for each edit.

E-E Mode - This stands for "electronics to electronics" and is a VTR mode in which the VTR processes the signals that it would normally use during recording but does not actually record onto the tape.

Electron Guns - The device in the CRT that produces the electron beam that is attracted to the phosphors on the face of the CRT; this activates the phosphors thus causing them to emit red, green, or blue light and create visual images on the CRT.

ENG - Abbreviation of Electronic News Gathering, meaning to use a portable video camera and recorder to record news events in the field.

Equalization - 1. Process of altering the frequency response of a video amplifier to compensate for high-frequency losses in coaxial cable. 2. In audio, to improve the sound quality by increasing or decreasing the gain of the signal at various frequencies.

Equalizing Pulses - Pulses that cause the vertical deflection to start at the same time in each interval, and also keep the horizontal sweep circuits in step during the portions of the vertical blanking interval immediately preceding and following the vertical sync pulse.

Farad - Unit of measurement for capacitance. More commonly: microfarads.

Fiber Optic - A transmission medium designed to transmit digital signals in the form of pulses of light. Fiber optic cable is noted for its properties of isolation from RF and electromagnetic interference, as well as resistance to electrostatic contamination.

Field - Half of the interlaced horizontal lines (262.5 in NTSC, 312.5 in PAL) needed to create a complete picture. Two interlaced fields create a complete monochrome frame or picture.

First Generation - The first copy of a videotape. A copy of that copy is termed second generation.

Flyback (Retrace) - The electron beam movement of the camera or television monitor back to the starting point for the next line or field.

Foot Candle - A unit of illumination from one candle at a distance of one foot. Equal to one lumen incident to one square foot.

Foot Lambert - The luminance (brightness) resulting from a surface emitting a luminance flux of one lumen per square foot. The luminance of a perfectly reflecting surface receiving an illumination of one footcandle.

Format - 1. In television, the specific form of the signals that make up the video signal. For example, component versus composite format. 2. To prepare or pre-program a storage medium, such as a floppy disk, so that it can receive and store data.

Frame - In interlaced video, a Frame is one complete picture. A Frame is made up of two fields, or two sets of interlaced lines. A frame consists of 525 interlaced horizontal lines of picture information in NTSC, 625 in PAL.

Frame Synchronizer - A digital buffer that, by storage, comparison of sync information to a reference, and timed release of video signals, can continuously adjust the signal for any timing errors.

Free-run - Condition in which a sync generator is not locked to any outside source but is providing sync on the basis of its own internal clock.

Frequency - The number of complete cycles of a periodic waveform that occur in a given length of time. Usually specified in cycles per second (Hertz).

Frequency Response - A measure of how effectively a circuit or device passes signals of different frequencies applied to it.

Fresnel Lens - A method of focusing light with a thin, flat lens by cutting circular grooves into its surface. The grooves act like concentric prisms to bend and focus the light. A fresnel lens is a fraction of the size and weight of a conventional lens, and the image is more distorted.

Front Porch - The black or blanking portion of the composite picture signal lying between the leading edge of the horizontal blanking pulse and the leading edge of the corresponding horizontal sync pulse.

Gain - A general term used to denote an increase in signal power or voltage produced by an amplifier in transmitting a signal from one point to another. The amount of gain is usually expressed in decibels above a reference level. Opposite of Attenuation.

Gamma - The light output of a CRT is not linear with respect to the voltage input. This non-linearity follows an exponential function called "Gamma".

General Purpose Interface (GPI) - 1. A parallel interconnection scheme that allows remote control of certain functions of a device. One wire per function. 2. May also refer to any non-specific interface between equipment. Usually refers to a serial connection (RS232 or RS422 format) between computer modules.

Generation Loss - Losses caused by copying from one videotape to another.

Genlock - The process of locking both sync and burst of one signal to sync and burst of another, making the two signals completely synchronous.

Graphics Monitor - A monitor with horizontal scan capable of 15.75-75 (80) kHz. Graphics monitors and projectors accept inputs from NTSC Video, CGA, and VGA as well as, high resolution workstations.

Graticule - The scale which is used to quantify the information on a waveform monitor or vectorscope display. Graticules may either be screened onto the faceplate of the CRT itself (internal graticule), or onto a piece of glass or plastic which fits in front of the CRT (external graticule). They can also be electronically generated.

Gray Scale - Range of luminance levels from black to white.

Ground Loop - A potential system grounding problem that may produce symptoms that appear as sync noise and causes a horizontal bar to "roll" vertically on the video image. A ground loop occurs when some devices in a system are not connected to the same electrical ground. This can create a voltage potential between "ground" on the different pieces of equipment.

Harmonic Distortion - If a sine wave of a single frequency is put into a system, and harmonic content at multiples of that frequency appears at the output, there is harmonic distortion present in the system. Harmonic distortion is caused by non-linearities in the system.

HDTV (High Definition Television) - The term describes several advanced standards proposals to allow high-resolution TV to be received in the home.

Hertz (Hz) - A measure of frequency in cycles per second.

Horizontal Blanking (Retrace) - The process of bringing the electron beam in a CRT back to the left side of the screen after a left to right line has been traced on the screen. The beam is shut off, blanked, during the period of retrace. About 83% of the total horizontal line time is spent writing the line. The remaining 17% is spent bringing the beam back to the left side; retrace, before starting the next time.

Horizontal Line - A single horizontal scan of a camera or CRT beam. A number of these video scans together form a frame of video. There are 525 interlaced lines per frame in NTSC, 625 in PAL.

Horizontal Period - The length of time for a complete horizontal line of video information.

Horizontal Rate (Frequency) - The number of complete horizontal lines, including trace and retrace, scanned per second. Shown as a measure of kHz.

Horizontal Resolution - Smallest increment of a television picture that can be discerned in the horizontal plane. This increment is dependent upon the video bandwidth and is measured in frequency. Determines the number of lines it takes to scan an image on the screen.

Horizontal Sync - Horizontal sync is the -40 IRE pulse occurring at the beginning of each line. This pulse signals the picture monitor to go back to the left side of the screen and trace another horizontal line picture information.

Hue (Tint Control) - Red, yellow, blue, etc. are hues of color or types of color. Hue is the parameter of color that allows us to distinguish between colors.

Hum - Unwanted coupling of 60 Hz power sine wave into other electrical signals. In audio, a "hum" can be heard; in video, waves in the picture.

Hum-bucker - 1. A circuit (often a coil) that introduces a small amount of voltage at power line frequency into the video path to cancel unwanted AC hum.

Hz (Hertz) - Frequency in cycles per second.

I - A designator used to name one of the color components of the NTSC video signal. The formula for deriving I from red, green, and blue is .60R-.28G-.32B. The term I also designates an M-Format color component.

IC (Integrated Circuit) - Combining many circuits into one module.

IDTV - Increased Definition Television. Example: scan doubling.

Impedance - (Z) The opposition or "load" to a signal. Circuits that generate audio or video signals, are designed to work with a certain "load", or impedance. Typical video impedances: 75 ohm or High Z.

Insert Edit (Insert Mode) - An edit mode in which the time code and control track already existing on the record tape are not replaced during the editing process. The system edits using the pre-recorded control track and time code.

Interlaced - The process of scanning whereby the alternate lines of both scanned fields fall evenly between each other.

IRE (Institute of Radio Engineers) - 1 Volt Peak - Peak Video is divided up into 140 IRE units. This is done to make numbers for luminance levels easier to communicate. The amplitude of the video signal from blanking (zero volts) to peak white is 0.714286 volts or 100 IRE units. Synchronization signals extend from blanking to - 1.285714 volts/ - 40 IRE units.

JPEG (Joint Photographic Experts Group) - A working committee under the auspices of the International Standards Organization (ISO) that is attempting to define a proposed universal standard for the digital compression and decompression of still images for use in computer systems. The JPEG algorithm reduces image size by as much as 65:1 while maintaining image integrity by eliminating imperceptible color information.

Jog, jogging - Process of moving the videotape forward or backward one field or frame at a time.

Kelvin - This is a system or scale used for measuring temperature. Absolute zero is 0 Kelvin or 273 C. The "color" of white light is expressed in terms of degrees Kelvin, the color of light emitted when an ideal object is heated to a particular temperature.

KiloHertz (kHz) - Thousands of Hertz, or a frequency rate in units of thousands of cycles per second. For example, CGAs horizontal scan rate is 15.75 kHz or 15,750 hertz (Hz).

LCD - Liquid Crystal Display. A device that displays text and graphics on a flat screen that uses no projected light or illumination.

LED - Light Emitting Diode.

Limiter - An electronic device in which some characteristics of the output is automatically prevented from exceeding a predetermined value.

Lenticulation - A cylindrical lens which causes light passing through it to be dispersed perpendicular to its axis.

Lenticular Screen - A large series of parallel lenticulations cut vertically into the screen surface to improve horizontal dispersion.

Linear - 1. Having an output that rises or falls in direct proportion to the input. 2. A straight-line motion path for objects in digital effects devices.

Line Doubler - An Increased Definition Television unit that doubles the number of scan lines in a video picture. This fills the space between the original lines, making them less noticeable.

Line Voltage - The voltage level of the main power source to a device.

Loop-Through - A type of video circuit input that provides two or more input connectors. One connector accepts the video input signal for use within the device in question, and the other connector provides a tap off of the input for routing the input signal to another piece of equipment.

Low Impedance - The condition where the source or load is at a lower impedance than the characteristic impedance of the cable. Low source impedances are common; low load impedances are usually fault conditions.

Lumen - A unit of measure for the amount of light emitted by a source.

Luminance - The signal which represents brightness, or the amount of light in the picture. This is the only signal required for black and white pictures, and for color systems it is obtained as a weighted sum (Y=0.3R+0.59G+0.11B) of the R, G and B signals.

LUX - The amount of light per square meter, incident on a surface. 1 lux = 1 lumen/squareómeter=0.093 footcandles.

MHz - An abbreviation for megahertz. This is a unit of measurement and refers to a million cycles per second. Bandwidth is measured in megahertz.

MII Format - A second-generation component video format invented by Panasonic for use in videotape recorders. The signal set consists of separate Y, scaled R-Y and scaled B-Y signals. The M refers to the way in which the tape is routed through the recording mechanism.

Moire - A pattern resulting from the combination of other patterns. In video, this is usually an undesirable pattern.

Monitor - 1. In video, a device that directly displays a video picture from a camera videotape recorder, or special effects generator. 2. A verb meaning to watch or listen to a signal.

Mosaic Effect - In digital picture manipulators, an effect where the picture seems to be made up of a number of small squares or tiles.

MPEG (Motion Picture Experts Group) - A standards committee under the auspices of the International Standards Organization working on algorithm standards that will allow digital compression, storage and transmission of moving image information such as motion video, CD-quality audio and control data at CD-ROM bandwidth. The MPEG algorithm provides inter-frame compression of video images and can have an effective compression rate of 100:1 to 200:1.

Mute - A mode that turns off the audio output to the monitor speakers. Used when a microphone is in the same room as the monitor.

NDF - Abbreviation of non-drop frame mode.

Noise - Unwanted disturbance within an electronic system. Interference present in a video picture.

Non-Composite Video Signal - A video signal that contains picture and blanking information only, no sync.

Non-Drop Frame Time Code - SMPTE time code format that continuously counts a full 30 frames per second. Because NTSC video does not operate at exactly 30 frames per second, non-drop frame time code will count 108 more frames in one hour than actually occur in the NTSC video in one hour. The result is incorrect synchronization of time code with clock time.

Non-Interlaced - Also called progressive scan - a method by which all the video scan lines are represented on the screen in one sweep instead of two.

Notch Filter - An arrangement of electronic components designed to attenuate a specific frequency band. Also called a band stop filter."

NTSC - National Television Standards Committee. Television standard for North America and certain countries in South America. 525 lines/60 Hz (90 Hz Refresh).

Off-line Editing - Editing that is done using inexpensive, non-broadcast-quality equipment to produce an edit decision list (EDL) which will be used later for assembling a broadcast-quality program using more expensive, high-quality equipment.

Oscillator - An electronic device that generates alternating-current at a frequency determined by the values of the components in its circuits.

Output - The current, voltage, power, or driving force delivered by a circuit or device.

Output Impedance - The impedance a device presents to its load. The impedance measured at the output terminals of a transducer with the load disconnected and all impressed driving forces taken as zero.

Overscan - A video monitor condition in which the raster extends slightly beyond the physical edges of the CRT screen, cutting off the outer edges of the picture.

PAL (Phase Alternate Line) - The phase of the color carrier is alternated from line to line. It takes four full pictures for the color to horizontal phase relationship to return to the reference point. This alternation helps cancel out phase errors, the reason the hue control is not needed on PAL TV sets. PAL, in its many forms is used extensively in Western Europe.

Peak-To-Peak - (p-p) - The amplitude (voltage) difference (as displayed on a oscilloscope) between the most positive and the most negative excursions (peaks) of an electrical signal.

Peaking - A means of compensating for mid and high frequency RGB Video Bandwidth response in data monitors and projectors and for signal losses due to cable capacitance. When using the Peak enhancements, use the following guidelines for proper output settings: Use 50% with all computer frequencies between 15-125 kHz at any cable length. Use 100% with high frequency computers of 36 kHz or higher with cable lengths 75 feet or greater.

Persistence - In essence, the "staying power" of a lighted phosphor, since a phosphor begins to dim after its excited by the electron gun(s), a long-persistence screen allows the phosphor to dim more slowly.

Phase (Chroma phase, hue, tint) - The relative timing of a signal in relation to another signal. If the time for one cycle of a signal is represented as 360o along a time axis, the phase position for the second signal is called phase angle expressed in degrees. The sub-carrier phase of TV colors can be adjusted and this changes the hue of the colors themselves.

Phasing - Adjusting the delay of a video signal to match a reference video signal. This includes horizontal and sub-carrier timing.

Phosphor - The chemical in the CRT which holds the light generated by the Red, Green and Blue electron guns. Each dot on the screen is actually a phosphor which glows for a given length of time.

Pink Noise - A uniform noise level over a given bandwidth, usually in the video frequency range.

Pixel - A definable location on a display screen that consists of multiple or single triad of dots (red, green, and blue.) A computer picture is typically composed of a rectangular array of pixels. The resolution of a picture is expressed by the number of pixels in the display. For example, a picture with 560x720 pixels is much sharper than a picture with 275x400 pixels.

Pluge (Picture Line Up Generation Equipment) - This is a name of a test pattern that assists in properly setting picture black level. PLUGE can be part of many test patterns. The phrase and origination of the test signal are both credited to the BBC.

Posterize, posterization - A digital video effect where all possible colors are converted to as few as 4 different colors, producing a poster effect

Preroll - A specific amount of time allowed for tape machines to run prior to an edit in order to get them up to speed and synchronized for the edit. In preparation for the edit, tapes are cued to a point ahead of the edit point to provide a proper preroll. The amount of preroll required varies with each type of VTR.

Preview - 1. To rehearse an edit without recording it. 2. To look at a video effect before taking it to air.

Primary Colors - Colors, usually three, which are combined to produce the full range of other colors within the limits of a system. All non-primary colors are mixtures of two or more of the primary colors. In television, the primary colors are specific sets of red, green and blue.

Processing Amplifier (Proc Amp) - A device that stabilizes the composite video signal, regenerates the synchronizing pulses and color burst, and can make other adjustments to the video signal.

Q - A designator used to name one of the color components of the NTSC composite video signal. The formula for deriving Q from red, green, and blue is .21R-.52G+.31B. The Q term also designates a color component of an M-Format component video signal.

Quad Split Generator - Splits the screen into four sections, each section containing a different video source.

Raster - The illuminated face of a video screen without the video information present. The pattern of scan lines on which a picture is produced.

Reference Video Signal - A composite video signal to which other signals are compared or locked for timing purposes.

Reset - To restore a device to its default or original state. To restore a counter or logic device to a known state, often a zero output.

Resolution - The density of lines or dots that make up an image. Resolution determines the detail and quality in the image.
A) A measure of the ability of camera or television system to reproduce detail.
B) In video, generally called horizontal resolution. It can be evaluated by establishing the limit to which lines can be distinguished on a test pattern. A larger resolution value means a broader frequency band of the video signal.
C) A measure of the greatest amount of detail that can be seen in an image. Often incorrectly expressed as a number of pixels in a given line; more correctly it is the bandwidth.

RF - Radio Frequency. In television applications, RF generally refers to the television signal after the picture carrier modulation process.

RGB (Red, Green, Blue) - The basic components of the color television system. They are also the primary colors of light, not to be confused with Cyan, Magenta, and Yellow, the primary pigments. Also called the "Additive Color Process".

RGB Monitor - A color monitor that uses color "guns" for red, green and blue to produce a high-quality picture.

RGB Video - A form of color video signal (red, green, blue) distinctly different from the composite color video used in standard television sets. RGB can be displayed only on a color monitor that has a separate electron gun for each of these primary colors. Some color television sets use only one gun. RGB monitors are noted for their crisp, bright colors and high resolution.

Retrace - During the scanning of a picture onto a screen, scan lines are produced from left to right. Before scanning the next line, the electron beam must get back to the left side of the screen. This is called "Retrace". The beam must be turned off (blanked) during retrace time.

Retrace Time - The minimum time required to move the scanning beam form the right side to the left side of the CRT screen.

Rise Time - The time required for a signal to go from 10% to 90% of its maximum amplitude level.

RMS - Abbreviation of root mean square. A measure of effective (as opposed to peak) voltage of an AC waveform. For a sine wave it is .707 times the peak voltage. For any periodic waveform, it is the square root of the average of the squares of the values through one cycle.

Routing Switcher - An electronic device that routes a user-supplied signal (audio, video, etc.) from any input to any user-selected output. Inputs are called sources. Outputs are called destinations.

RS-170A - EIA technical standard NTSC color TV.

RS-232C - An Electronic Industries Association (EIA) serial digital interface standard specifying the electrical and mechanical characteristics of the communication path between two devices using D-type connectors. This standard is used for relatively short range communications and does not specify balanced control lines.

RS-422 - An EIA serial digital interface standard which specifies the electrical characteristics of balanced voltage digital interface circuits. This standard is usable over longer distances than RS-232C. Although originally designed for use with 9-pin and 37-pin, D-type connectors, it is often used with others, including 25-pin D-types. It is also used as the serial port standard for Macintosh computers. This signal governs the asynchronous transmission of computer data at speeds of up to 920,000 bits per second.

R-Y - One of the color difference signals used in the NTSC system, obtained by subtracting luminance from the red camera signal. R-Y signal drives the vertical axis of a vectorscope.

Saturation - The intensity of the color is called saturation. For example, a lightly saturated red looks pink. Fully saturated red is like the red of a crayon. On a display device, it can be adjusted with the Color control. Not to be confused with the brightness, saturation is the amount of pigment in a color, and not the intensity. Low saturation is like adding white to the color.

Scan-Doubling - The process of eliminating the visible video scan lines by doubling them and filling the "blank" lines.

Scanning - The process of moving the electron beam across the surface of the video screen, or CRT.

Schematic - A diagram of the electrical scheme of a circuit with components represented by graphic symbols.

SECAM (Sequential Couleur Ave Memoire) - Translated as "Sequential Color with Memory". A composite color transmission system that potentially eliminates a need for both a color and hue control on the monitor. One of the color difference signals is transmitted on one line and the second is transmitted on the second line. Memory is required to obtain both color difference signals for color decoding. This system is used in France, Africa, Asia and many Eastern European countries.

Serial - Time-sequential transmission of data along a single wire. Analogous to a railroad train, where each car (data bit) follows the other in single file.

Serial Control Panel - A control panel separate from the switcher (for example, a routing switcher) that communicates with the switcher via a serial connection.

Serial Interface - A digital communications interface in which data is transmitted and received sequentially along a single wire or pair of wires. Common serial interface standards are RS232 and RS 422.

Serration - A vertical synchronizing pulse divided into a number of small pulses, each acting for the duration of half a line in a television system. Serrations are used to keep the horizontal oscillator synchronized during the vertical sync pulse interval in early televisions.

Set-up (Black Reference, Black Level) - 1. The specified base of the active picture signal which is at reference black level. Called set-up because it is placed 7.5 IRE units above blanking (zero IRE) in NTSC video. 2. The basic operating configuration of a system.

Shadow Mask - A metal plate with holes or vertical lines that is used to properly position where the electron beam strikes the CRT screen.

Signal - A waveform used to convey information from one point to another.

Signal to Noise Ratio - (SNR, S/N) - Expressed in decibels, the signal to noise ratio relates how much stronger a signal is than the background noise.

Slave - Component in a system that does not act independently, but only under the control of another component.

SMPTE - Society of Motion Picture and Television Engineers - A global organization, based in the United States, that sets standards for baseband visual communications. This includes film as well as video standards.

SMPTE Time Code - Time code that conforms to SMPTE standards. It consists of an eight-digit number specifying hours: minutes: seconds: frames. Each number identifies one frame on a videotape. SMPTE time code may be of either the drop-frame or non-drop frame type.

Split Edit - An edit in which the audio in-edit point is different from the corresponding video in-edit point.

Subcarrier - The modulation sidebands of the color subcarrier contain the R-Y and B-Y information. For NTSC, subcarrier frequency is 3.579545 MHz.

Super VGA - A term used to denote higher that VGA (640 x 480) resolution. Most Super VGA computers/cards output resolutions up to 1280 x 1024 and 16 million colors.

Switcher (Production Switcher) - Device that allows transitions between different video pictures. May also contain special effects generators.

Sync - In video, a means of synchronizing signals with timing pulses to insure that each step in a process occurs at exactly the right time. For example: Horizontal Sync determines exactly when to begin each horizontal line (sweep) of the electron beam. Vertical Sync determines when to bring the electron beam to the top-left of the screen to start a new field. There are many other types of sync in a video system. (Also called Sync Signal or Sync Pulse.)

S-VHS - A high band video recording process for VHS that increases the picture quality and resolution capability.

S-Video - The composite video signal is separated into the Luminance (Y) and the Chrominance (C).

Termination - A load at the end of a cable or signal line used to match the impedance of the equipment being used. Usually a close-tolerance resistor for each signal, a terminator is often mounted in its own connector, making it easy to install. The resistor absorbs signal energy to prohibit signal reflections back toward the source. This causes the source equipment to operate as if the line is connected to equipment of equal impedance.

Terminator - Device, usually having its own connector, that provides termination for a signal line, or several signal lines, at the end of a cable.

Time Base Corrector - Device used to correct for time base errors and stabilize the timing of the video output from a tape machine.

Time Base Error - Horizontal rate flutter of a video signal caused by tape stretch and inherent imperfections in the tape transport mechanism of a videotape recorder.

Time Code - A digital or binary code is used to label each frame of a video signal. This is very useful for editing the video since the time code is in the form of hours, minutes, seconds and frames.

Transcoder - A device that converts one form of encoded video to another, e.g., to convert NTSC video to PAL. Sometimes mistakenly used to mean translator.

Translator - A device used to convert from one component set to another, e.g. to convert Y, R-Y, B-Y signals to RGB signals.

TTL - Transistor or Transistor Logic. Digital type signal, usually 4-5 volts peak to peak. Distance limitation is 6-10 feet. Signal splitting is acceptable. TTL signals are either "ON" or "OFF" and is characteristic of low resolution computers (CGA/EGA).

Triaxial - A special form of coaxial cable containing three conductors.

UHF - Ultra High Frequency

Underscan - A decreasing of the raster size (H & V) so that all four edges of the picture are visible on the screen. Underscanning allows viewing of skew and tracking which would not be visible in normal (overscanned) mode. It is also helpful when aligning test charts to be certain they touch all four corners of the raster. Likewise, when checking the alignment of multiplexer images from a film chain, underscan allows proper framing of the projected image going into the video camera.

Unity Gain - An amplifier or active circuit in which the output amplitude is the same as the input amplitude.

Unmodulated - When used to describe television test signals, this term refers to pulses and pedestals which do not have high-frequency chrominance information added to them.

Vectorscope - A trademarked name that has become the generic description for a vector display unit which allows visual checking of the phase and amplitude of the color components of a video signal.

Vertical Banking Interval - The blanking time at the beginning of each field. It contains equalizing pulses and vertical sync pulses.

Vertical Blanking (Retrace) - The tuning off of the scanning electron beam in a CRT during the time the beam must return from the bottom of the screen to the top. Vertical Blanking occurs between writing each field of a picture. If Vertical Blanking does not occur, a diagonal "retrace" line will display from lower right to upper left of the screen.

Vertical Interval - The synchronizing information which is presented between fields, and then signals the picture monitor to return to the top of the screen to start another vertical scan.

Vertical Resolution - Chrominance and luminance detail expressed vertically in the picture tube. Limited by the number of scan lines.

VGA - Video Graphics Array, Introduced by IBM in 1987, VGA is an Analog signal with TTL level separate horizontal and vertical sync. The video outputs to a 15-pin, HD connector and has a horizontal scan frequency of 31.5 kHz and vertical frequency of 70 Hz (Mode 1, 2) and 60 Hz (Mode 3). The signal is non-interlaced in modes 1, 2, 3 and interlaced when using the 8514/A card (35.5 kHz, 86 Hz) in mode 4. It has a Pixel by Line resolution of 640 x 480 with a color palette of 16/256,000.

Video Distribution Amplifier - An amplifier for strengthening the video signal so that it can be supplied to a number of video monitors at the same time.

Video Signal - An electrical signal that includes all the information present in the television picture together with the necessary synchronizing signals.

Video Switcher (production switcher, video mixer) - Device that accepts inputs form a variety of video sources and allows the operator to select a particular source to be sent ot the switchers output(s). May also include circuits for video mixing, wiping, keying, and other special effects.

Videotape Recorder (Video Tape Recorder, VTR) - A device which permits audio and video signals to be recorded on magnetic tape.

VITC - Abbreviation of vertical interval time code. Time code encoded into the vertical interval of the video. It usually can be read out even when a VTR is still-framed or running at slower or faster than play speed.

VU meter - Abbreviation of volume-unit meter, a type of meter used to indicate average audio amplitude.

Waveform Monitor - A device used to examine the video signal and synchronizing pulses. An oscilloscope designed especially for viewing the waveform of a video signal.

Wow and Flutter - Wow refers to low-frequency variations in pitch while flutter refers to high frequency variations in pitch caused by variations in the tape-to-head speed of a tape machine.

WYSIWYG - Abbreviation of "what you see is what you get". The final product looks exactly like what is seen on a monitor.

XGA - Extended Graphics Array card. IBMs graphics standard that includes VGA and extended resolutions up to 1024 x 768, interlaced; 35 kHz. This card has a 15-pin HD connector.

XGA-2 - Extended Graphics Array card, 2nd Generation. Capable of scanning form 31 to 68 kHz and resolutions up to 1600 x 1200 pixels. This card has a 15-pin HD connector.

Y - In video, "Y" is an abbreviation for Luminance. Y = 0.3Red + .59Green + .11Blue

Y, R-Y, B-Y- Color difference signal designation. Y corresponds to the luminance signal, R-Y corresponds to the red minus luminance signal, and B-Y corresponds to the blue minus luminance signal. These signals are derived as follows:
Y = 0.3Red + .59Green + .11Blue
R-Y = 0.7Red -0.59Green - 0.11Blue
B-Y = 0.89Blue - 0.59Green - 0.3Red

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

Z - A symbol for impedance.