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.
NTSC is the first American standard for analog television, published in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170.
Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) systems, which, in turn, were replaced by flat-panel displays of several types.
Closed captioning (CC) and subtitling are both processes of displaying text on a television, video screen, or other visual display to provide additional or interpretive information. Both are typically used as a transcription of the audio portion of a program as it occurs, sometimes including descriptions of non-speech elements. Other uses have included providing a textual alternative language translation of a presentation's primary audio language that is usually burned-in to the video and unselectable.
Digital Visual Interface (DVI) is a video display interface developed by the Digital Display Working Group (DDWG). The digital interface is used to connect a video source, such as a video display controller, to a display device, such as a computer monitor. It was developed with the intention of creating an industry standard for the transfer of uncompressed digital video content.
A waveform monitor is a special type of oscilloscope used in television production applications. It is typically used to measure and display the level, or voltage, of a video signal with respect to time.
Broadcasttelevision systems are the encoding or formatting systems for the transmission and reception of terrestrial television signals.
The refresh rate, also known as vertical refresh rate or vertical scan rate in reference to terminology originating with the cathode-ray tubes (CRTs), is the number of times per second that a raster-based display device displays a new image. This is independent from frame rate, which describes how many images are stored or generated every second by the device driving the display. On CRT displays, higher refresh rates produce less flickering, thereby reducing eye strain. In other technologies such as liquid-crystal displays, the refresh rate affects only how often the image can potentially be updated.
MovieBeam was a video on demand service started by The Walt Disney Company, specifically its subsidiary Buena Vista Datacasting, LLC. Movies were sent wirelessly into the subscriber's home by embedding digital data (datacasting) within local Public Broadcasting Service (PBS) stations' analog TV (NTSC) broadcast to deliver the movies to a set-top box. The data was embedded using dNTSC technology licensed from Dotcast, and distributed to TV stations via National Datacast through the vertical blanking interval, the same method used to provide closed captioning. Up to ten new movies were delivered to the player each week. The player also contained free movie trailers, previews, and other extras.
Overscan is a behaviour in certain television sets in which part of the input picture is cut off by the visible bounds of the screen. It exists because cathode-ray tube (CRT) television sets from the 1930s to the early 2000s were highly variable in how the video image was positioned within the borders of the screen. It then became common practice to have video signals with black edges around the picture, which the television was meant to discard in this way.
NABTS, the North American Broadcast Teletext Specification, is a protocol used for encoding NAPLPS-encoded teletext pages, as well as other types of digital data, within the vertical blanking interval (VBI) of an analog video signal. It is standardized under standard EIA-516, and has a rate of 15.6 kbit/s per line of video. It was adopted into the international standard CCIR 653 of 1986 as CCIR Teletext System C.
Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipped television sets. Teletext sends data in the broadcast signal, hidden in the invisible vertical blanking interval area at the top and bottom of the screen. The teletext decoder in the television buffers this information as a series of "pages", each given a number. The user can display chosen pages using their remote control. In broad terms, it can be considered as Videotex, a system for the delivery of information to a user in a computer-like format, typically displayed on a television or a dumb terminal, but that designation is usually reserved for systems that provide bi-directional communication, such as Prestel or Minitel.
Horizontal scan rate, or horizontal frequency, usually expressed in kilohertz, is the number of times per second that a raster-scan video system transmits or displays a complete horizontal line, as opposed to vertical scan rate, the number of times per second that an entire screenful of image data is transmitted or displayed.
Horizontal blanking interval refers to a part of the process of displaying images on a computer monitor or television screen via raster scanning. CRT screens display images by moving beams of electrons very quickly across the screen. Once the beam of the monitor has reached the edge of the screen, it is switched off, and the deflection circuit voltages are returned to the values they had for the other edge of the screen; this would have the effect of retracing the screen in the opposite direction, so the beam is turned off during this time. This part of the line display process is the Horizontal Blank.
Guide Plus+, TV Guide On Screen, TV Guide Daily, TV Guide Plus+ and Guide Plus+ Gold or G-Guide are brand names for an interactive electronic program guide (EPG) system that is used in consumer electronics products, such as television sets, DVD recorders, personal video recorders, and other digital television devices. It offers interactive on-screen program listings that enable viewers to navigate, sort, select and schedule television programming for viewing and recording. The differing names are only used for marketing purposes – the entire system is owned by Rovi Corporation, the successor to Gemstar-TV Guide International. In 2016, Rovi acquired digital video recorder maker TiVo Inc., and renamed itself TiVo Corporation.
A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics, the pattern of image storage and transmission used in most computer bitmap image systems. The word raster comes from the Latin word rastrum, which is derived from radere ; see also rastrum, an instrument for drawing musical staff lines. The pattern left by the lines of a rake, when drawn straight, resembles the parallel lines of a raster: this line-by-line scanning is what creates a raster. It is a systematic process of covering the area progressively, one line at a time. Although often a great deal faster, it is similar in the most general sense to how one's gaze travels when one reads lines of text.
National Datacast Incorporated (NDI) was a pioneer in data broadcasting. It was a for-profit subsidiary of the Public Broadcasting Service (PBS), which had a minority stake in the final years of this subsidy. It handled datacasting on PBS TV stations throughout the United States. Services using ATSC digital TV included MovieBeam and UpdateTV. UpdateTV continues to be operated by its present owner, Qterics, leasing bandwidth to other companies for the purpose of automatic television firmware updates.
In analog video, blanking occurs between horizontal lines and between frames. In raster scan equipment, an image is built up by scanning an electron beam from left to right across a screen to produce a visible trace of one scan line, reducing the brightness of the beam to zero, moving it back as fast as possible to the left of the screen at a slightly lower position, restoring the brightness, and continuing until all the lines have been displayed and the beam is at the bottom right of the screen. Its intensity is then reduced to zero again, and it is rapidly moved to the top left to start again, creating the next frame.
In general, synchronizations is the process in which the signals are transmitted and received in accordance with the clock pulses. In synchronization of Television transmitter, a sharp pulse is sent between each video signal line so that to maintain the impeccable transmitter-receiver synchronization. The receiver detects the video signal, synchronizing the transmitter and receiver is necessary to overcome the delay between different video packet arrivals. The receiver must start scanning same line on the CRT output display or picture tube when the TV camera starts scanning that line, these are the horizontal lines that are being scanned. The scanning speed of transmitter and receiver must be same so as to avoid signal distortion and deformation at the image in receiver output. When horizontal lines are completely scanned, vertical flyback or retrace must occur simultaneously at both transmitter and receiver moving the electron beam from bottom line end to the start of the top line. When the electron beam is returned to the left-hand side to start tracing a new line during the horizontal retrace, must occur inadvertently at both transmitter and receiver.
JTES, the Japanese Teletext Specification, is a protocol used for encoding teletext pages, as well as other types of digital data, within the vertical blanking interval (VBI) of an analog video signal in Japan. It was adopted into the international standard CCIR 653 of 1986 as CCIR Teletext System D.
