Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal.
The National Television System Committee (NTSC) developed the analog television color system that was introduced in North America in 1954 and stayed in use until digital conversion. It is one of three major analog color television standards, the others being PAL and SECAM. All the countries using NTSC are currently in the process of conversion, or have already converted to the ATSC standard, or to DVB, ISDB or DTMB.
A phase-locked loop or phase lock loop (PLL) is a control system that generates an output signal whose phase is related to the phase of an input signal. There are several different types; the simplest is an electronic circuit consisting of a variable frequency oscillator and a phase detector in a feedback loop. The oscillator generates a periodic signal, and the phase detector compares the phase of that signal with the phase of the input periodic signal, adjusting the oscillator to keep the phases matched.
A signal generator is one of a class of electronic devices that generates electronic signals with set properties of amplitude, frequency, and wave shape. These generated signals are used as a stimulus for electronic measurements, typically used in designing, testing, troubleshooting, and repairing electronic or electroacoustic devices, though it often has artistic uses as well.
Colorburst is an analog video, composite video signal generated by a video-signal generator used to keep the chrominance subcarrier synchronized in a color television signal. By synchronizing an oscillator with the colorburst at the back porch (beginning) of each scan line, a television receiver is able to restore the suppressed carrier of the chrominance (color) signals, and in turn decode the color information. The most common use of colorburst is to genlock equipment together as a common reference with a vision mixer in a television studio using a multi-camera setup.
Composite video is an analog video signal format that carries standard-definition video as a single channel. Video information is encoded on one channel, unlike the higher-quality S-video and the even higher-quality component video. In all of these video formats, audio is carried on a separate connection.
S-Video is a signaling standard for standard definition video, typically 480i or 576i. By separating the black-and-white and coloring signals, it achieves better image quality than composite video, but has lower color resolution than component video. S-Video was introduced with JVC's S-VHS format in 1987.
Component video is an analog video signal that has been split into two or more component channels. In popular use, it refers to a type of component analog video (CAV) information that is transmitted or stored as three separate signals. Component video can be contrasted with composite video in which all the video information is combined into a single signal that is used in analog television. Like composite, component-video cables do not carry audio and are often paired with audio cables.
Serial digital interface (SDI) is a family of digital video interfaces first standardized by SMPTE in 1989. For example, ITU-R BT.656 and SMPTE 259M define digital video interfaces used for broadcast-grade video. A related standard, known as high-definition serial digital interface (HD-SDI), is standardized in SMPTE 292M; this provides a nominal data rate of 1.485 Gbit/s.
A pulse generator is either an electronic circuit or a piece of electronic test equipment used to generate rectangular pulses. Pulse generators are used primarily for working with digital circuits, related function generators are used primarily for analog circuits.
A composite monitor or composite video monitor is any analog video display that receives input in the form of an analog composite video signal to a defined specification. A composite video signal encodes all information on a single conductor; a composite cable has a single live conductor plus earth. Other equipment with display functionality includes monitors with more advanced interfaces and connectors giving a better picture, including analog VGA, and digital DVI, HDMI, and DisplayPort; and television (TV) receivers which are self-contained, receiving and displaying video RF broadcasts received with an internal tuner. Video monitors are used for displaying computer output, closed-circuit television and other applications requiring a two-dimensional monochrome or colour image.
Time base correction is a technique to reduce or eliminate errors caused by mechanical instability present in analog recordings on mechanical media. Without time base correction, a signal from a videotape recorder (VTR) or videocassette recorder (VCR) cannot be mixed with other, more time-stable devices found in television studios and post-production facilities. Most broadcast quality VCRs have simple time base correctors built in though external time base correctors (TBCs) are often used. Some high-end domestic analog video recorders and camcorders also include a TBC circuit, which typically can be switched off if required.
A video signal generator is a type of signal generator which outputs predetermined video and/or television oscillation waveforms, and other signals used in the synchronization of television devices and to stimulate faults in, or aid in parametric measurements of, television and video systems. There are several different types of video signal generators in widespread use. Regardless of the specific type, the output of a video generator will generally contain synchronization signals appropriate for television, including horizontal and vertical sync pulses or sync words. Generators of composite video signals will also include a colorburst signal as part of the output.
A digital delay generator is a piece of electronic test equipment that provides precise delays for triggering, syncing, delaying and gating events. These generators are used in many types of experiments, controls and processes where electronic timing of a single event or multiple events to a common timing reference is needed. The digital delay generator may initiate a sequence of events or be triggered by an event. What differentiates it from ordinary electronic timing is the synchronicity of its outputs to each other and to the initiating event.
An oscilloscope, previously called an oscillograph, and informally known as a scope or o-scope, CRO, or DSO, is a type of electronic test instrument that graphically displays varying signal voltages, usually as a calibrated two-dimensional plot of one or more signals as a function of time. The displayed waveform can then be analyzed for properties such as amplitude, frequency, rise time, time interval, distortion, and others. Originally, calculation of these values required manually measuring the waveform against the scales built into the screen of the instrument. Modern digital instruments may calculate and display these properties directly.
This glossary defines terms that are used in the document "Defining Video Quality Requirements: A Guide for Public Safety", developed by the Video Quality in Public Safety (VQIPS) Working Group. It contains terminology and explanations of concepts relevant to the video industry. The purpose of the glossary is to inform the reader of commonly used vocabulary terms in the video domain. This glossary was compiled from various industry sources.
In video, frame synchronization is the process of synchronizing display pixel scanning to a synchronization source. When several systems are connected, a synchronization signal is fed from the synchronization source to the other systems in the network, and the video signals are synchronized with each other.
Color television as introduced in North America in 1954 is best described as being 'colored' television. The system used the existing black and white signal but with the addition of a component intended only for television receivers designed to show color. By careful application this 'colored' signal was ignored by ordinary TV sets and had negligible effect on the appearance of the black and white image. This meant that color programs were viewable on the many existing black and white receivers which fulfilled a requirement for 'compatibility' desired by the television industry. Once the so called 'composite' video signal containing the color component had been generated it could be handled just as if it were a black and white signal, eliminating the need to replace much of the existing TV infrastructure. Colorplexer was the RCA name for the equipment that created this 'composite' color signal from three separate images each created in the primary colors, Red, Green and Blue supplied by a color video camera. This process was by the standards of the day quite complex and demanded accurate control of all the various parameters involved if an acceptable color image was to be achieved. The simplification afforded by this 'head end' approach became evident and contributed to the gradual acceptance of color programming over the following decades.
Tri-level sync is an analogue video synchronization pulse primarily used for the locking of high-definition video signals (genlock).
Black and burst, also known as bi-level sync and black burst, is an analogue signal used in broadcasting. It is a composite video signal with a black picture. It is a reference signal to synchronise video equipment, in order to have them output video signals with the same timing. This allows seamless switching between two video signals.
