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CCIR System F
CCIR System F was an adaptation of System E used in Belgium (1953, '' RTB'') and Luxembourg (1955, '' Télé Luxembourg''). With only half the vision bandwidth and approximately half the sound carrier offset, it allowed French 819-line programming to squeeze into the 7 MHz VHF broadcast channels used in those neighboring countries, albeit with a substantial loss of horizontal resolution. Use of System F was discontinued in Belgium in February 1968, and in Luxembourg in September 1971. Between 1976 and 1981 when French channel TF1 was switching area by area to the new analog 625-lines UHF network with SECAM colour, some transmitters and gapfillers broadcast the 819-line signal in UHF.TDF:situation des émetteurs au 31 December 1980 When switching to 625-lines, most gapfillers did not change UHF channel (e.g. many gapfillers using this transmission located in French Alps near Grenoble, Mont Salève and Geneva began broadcasting on UHF channel 42, and continue to use thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCIR System E
CCIR System E is an analog broadcast television system used in France and Monaco, associated with monochrome 819-line high resolution broadcasts. Transmissions started in 1949 and ended in 1985. System E specifications Some of the important specs are listed below:Reference Data for Radio Engineers, ITT Howard W.Sams Co., New York, 1977, section 30 * Frame rate: 25 Hz * Interlace: 2/1 * Field rate: 50 Hz * Lines/frame: 819 * Line rate: 20.475 kHz * Visual bandwidth: 10 MHz * Vision modulation: Positive * Preemphasis: none * Sound modulation: AM * Sound offset: +11.15 MHz on odd numbered channels, -11.15 MHz on even numbered channels * Channel bandwidth: 14 MHz System E implementation provided very good (near HDTV) picture quality but with an uneconomical use of bandwidth. With the usual additions of sound carrier and vestigial sideband the result was a combined signal that demanded approximately two to three times the bandwidth of more ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salève
The Salève (), or Mont Salève, is a mountain of the French Prealps located in the department of Haute-Savoie in Auvergne-Rhône-Alpes. It is also called the "Balcony of Geneva" (French: ''Balcon de Genève''). Geography Geographically, the Salève is a mountain of the French Prealps located in the Haute-Savoie department, but geologically a part of the Jura chain, as the Vuache is. Below the Salève is the Geneva urban area where more than 700,000 people live. The Salève consists of the Pitons, Grand Salève and Petit Salève; it culminates at 1,379 metres at the Grand Piton. It is accessible via the Téléphérique du Salève, a cable car, since 1932 (rebuilt in 1983). The Salève stretches between Étrembières in the north and the suspension bridge of La Caille in the south. Between 1892 and 1935, the Salève was served by the first electric rack railway in the world ( Chemin de fer du Salève). The eastern side of the Salève dives under the molasse of the B ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Television Technology
The technology of television has evolved since its early days using a mechanical system invented by Paul Gottlieb Nipkow in 1884. Every television system works on the scanning principle first implemented in the rotating disk scanner of Nipkow. This turns a two-dimensional image into a time series of signals that represent the brightness and color of each resolvable element of the picture. By repeating a two-dimensional image quickly enough, the impression of motion can be transmitted as well. For the receiving apparatus to reconstruct the image, synchronization information is included in the signal to allow proper placement of each line within the image and to identify when a complete image has been transmitted and a new image is to follow. While mechanically scanned systems were experimentally used, television as a mass medium was made practical by the development of electronic camera tubes and displays. By the turn of the 21st century, it was technically feasible to replace ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-R Recommendations
The ITU Radiocommunication Sector (ITU-R) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU) and is responsible for radio communications. Its role is to manage the international radio-frequency spectrum and satellite orbit resources and to develop standards for radiocommunication systems with the objective of ensuring the effective use of the spectrum. ITU is required, according to its constitution, to allocate spectrum and register frequency allocation, orbital positions and other parameters of satellites, "in order to avoid harmful interference between radio stations of different countries". The international spectrum management system is therefore based on regulatory procedures for frequency coordination, notification and registration. ITU-R has a permanent secretariat, the Radiocommunication Bureau, based at the ITU HQ in Geneva, Switzerland. The elected Director of the Bureau is Mario Maniewicz; he was first elected by t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transposer
In broadcasting, a transposer or translator is a device in or beyond the service area of a radio or television station transmitter that rebroadcasts signals to receivers which can’t properly receive the signals of the transmitter because of a physical obstruction (like a hill). A translator receives the signals of the transmitter and rebroadcasts the signals to the area of poor reception. Sometimes the translator is also called a ''relay transmitter'', ''rebroadcast transmitter'' or ''transposer.'' Since translators are used to cover a small shadowed area, their output powers are usually lower than that of the radio or television station transmitters feeding them. Physical obstruction Reception of RF signals is sensitive to the size of obstruction in the path between the transmitter and the receiver. Generally speaking, if the size exceeds the wavelength the reception is interrupted. Since the wavelength is inversely proportional to frequency, it follows than that the higher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Television Transmitter
A television transmitter is a transmitter that is used for terrestrial television, terrestrial (over-the-air) television broadcasting. It is an electronic device that radiates radio waves that carry a video signal representing moving images, along with a synchronized audio signal, audio channel, which is received by television receivers ('televisions' or 'TVs') belonging to a public audience, which display the image on a screen. A television transmitter, together with the Television studio, broadcast studio which originates the content, is called a television station. Television transmitters must be licensed by governments, and are restricted to a certain frequency channel and power level. They transmit on frequency television channel frequencies, channels in the very high frequency, VHF and ultrahigh frequency, UHF bands. Since radio waves of these frequencies travel by line-of-sight propagation, line of sight, they are limited by the horizon to reception distances of 40–60 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Broadcast Television Systems
Broadcast television systems (or terrestrial television systems outside the US and Canada) are the encoding or formatting systems for the transmission and reception of terrestrial television signals. Analog television systems were standardized by the International Telecommunication Union (ITU) in 1961, with each system designated by a letter ( A- N) in combination with the color standard used (NTSC, PAL or SECAM) - for example PAL-B, NTSC-M, etc.). These analog systems for TV broadcasting dominated until the 2000s. With the introduction of digital terrestrial television (DTT), they were replaced by four main systems in use around the world: ATSC, DVB, ISDB and DTMB. Analog television systems Every analog television system bar one began as a black-and-white system. Each country, faced with local political, technical, and economic issues, adopted a color television standard which was grafted onto an existing monochrome system such as CCIR System M, using gaps in the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emphasis (telecommunications)
In signal processing, pre-emphasis is a technique to protect against anticipated noise and loss. The idea is to boost (and hence distort) the frequency range that is most susceptible to noise and loss beforehand, so that after a noisy and lossy process (transmission over cable, tape recording...) more information can be recovered from that frequency range. Removal of the distortion caused by pre-emphasis is called de-emphasis, making the output accurately reproduce the original input. Emphasis is commonly used in many places ranging from FM broadcasting ( preemphasis improvement) and vinyl (e.g. LP) records to PCI Express. For example, high-frequency signal components may be emphasized to produce a more equal modulation index for a transmitted frequency spectrum, and therefore a better signal-to-noise ratio for the entire frequency range. In audio signals In processing electronic audio signals, pre-emphasis refers to a system process designed to increase (within a frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modulation
Signal modulation is the process of varying one or more properties of a periodic waveform in electronics and telecommunication for the purpose of transmitting information. The process encodes information in form of the modulation or message signal onto a carrier signal to be transmitted. For example, the message signal might be an audio signal representing sound from a microphone, a video signal representing moving images from a video camera, or a digital signal representing a sequence of binary digits, a bitstream from a computer. This carrier wave usually has a much higher frequency than the message signal does. This is because it is impractical to transmit signals with low frequencies. Generally, receiving a radio wave requires a radio antenna with a length that is one-fourth of the wavelength of the transmitted wave. For low frequency radio waves, wavelength is on the scale of kilometers and building such a large antenna is not practical. Another purpose of modulation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scan Line
A scan line (also scanline) is one line, or row, in a raster scanning pattern, such as a line of video on a cathode-ray tube (CRT) display of a television set or computer monitor. On CRT screens the horizontal scan lines are visually discernible, even when viewed from a distance, as alternating colored lines and black lines, especially when a progressive scan signal with below maximum vertical resolution is displayed. This is sometimes used today as a visual effect in computer graphics. The term is used, by analogy, for a single row of pixels in a raster graphics image. Scan lines are important in representations of image data, because many image file formats have special rules for data at the end of a scan line. For example, there may be a rule that each scan line starts on a particular boundary (such as a byte or word; see for example BMP file format). This means that even otherwise compatible raster data may need to be analyzed at the level of scan lines in order to conver ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Film Frame
In filmmaking, video production, animation, and related fields, a frame is one of the many '' still images'' which compose the complete ''moving picture''. The term is derived from the historical development of film stock, in which the sequentially recorded single images look like a framed picture when examined individually. The term may also be used more generally as a noun or verb to refer to the edges of the image as seen in a camera viewfinder or projected on a screen. Thus, the camera operator can be said to keep a car in frame by panning with it as it speeds past. Overview When the moving picture is displayed, each frame is flashed on a screen for a short time (nowadays typically , , or of a second) and then immediately replaced by the next one. Persistence of vision blends the frames together, producing the illusion of a moving image. The frame is also sometimes used as a unit of time, so that a momentary event might be said to last six frames, the actual duration of w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Refresh Rate
The refresh rate, also known as vertical refresh rate, vertical scan rate or vertical frequency 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. Non-raster displays may not have a characteristic refresh rate. Vector displays, for instance, do not trace the entire screen, only the actual lines comprising the displayed image, so refresh speed may differ by the size and complexity of the image data. For computer programs or telemetry, the term is sometimes applied to how frequently a datum is updated with a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
