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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] |
Terrestrial Television
Terrestrial television, or over-the-air television (OTA) is a type of television broadcasting in which the content is signal transmission, transmitted via radio waves from the terrestrial (Earth-based) transmitter of a TV station to a TV receiver having an television antenna, antenna. The term ''terrestrial'' is more common in Europe and Latin America, while in Canada and the United States it is called ''over-the-air'' or simply ''broadcast''. This type of Television broadcasting, TV broadcast is distinguished from newer technologies, such as satellite television (direct broadcast satellite or DBS television), in which the signal is transmitted to the receiver from an overhead satellite; cable television, in which the signal is carried to the receiver through a coaxial cable, cable; and Internet Protocol television, in which the signal is received over an Internet stream or on a network utilizing the Internet Protocol. Terrestrial television stations broadcast on television cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luma (video)
In video, luma (Y') represents the brightness in an image (the "black-and-white" or achromatic portion of the image). Luma is typically paired with chrominance. Luma represents the grey, achromatic image, while the chroma components represent the color information. Converting RGB color model, R′G′B′ sources (such as the output of a three-CCD camera) into luma and chroma allows for chroma subsampling: because human vision has finer spatial sensitivity to luminance ("black and white") differences than chromatic differences, video systems can store and transmit chromatic information at lower resolution, optimizing perceived detail at a particular bandwidth. Luma versus relative luminance Luma is the weighted sum of gamma-compressed R′G′B′ components of a color video—the ''prime symbols'' ′ denote Gamma correction, gamma compression. The word was proposed to prevent confusion between luma as implemented in video engineering and relative luminance as used in color s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CCIR System B
CCIR System B (originally known as the "Gerber Standard") was the 625-line VHF analog broadcast television system which at its peak was adopted by more than one hundred countries, either with PAL or SECAM colour. It is usually associated with CCIR System G for UHF broadcasts. System B was the first internationally accepted 625-line broadcasting standard in the world. A first 625-line system with a 8 MHz channel bandwidth was proposed at the CCIR Conference in Stockholm in July 1948 (based on 1946-48 studies in the Soviet Union by Mark KrivosheevOn the beginning of broadcast in 625-lines 60 year s ago, ''625'' magazine (in Russian). ). At a CCIR Geneva meeting in July 1950 Dr. Gerber (a Swiss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
819 Line
819-line was an analog monochrome TV system developed and used in France as television broadcast resumed after World War II. Transmissions started in 1949 and were active up to 1985, although limited to France, Belgium and Luxembourg. It is associated with CCIR System E and F. History When Europe resumed TV transmissions after World War II (i.e. in the late 1940s and early 1950s) most countries standardized on 625-line television systems. The two exceptions were the British 405-line system, which had already been introduced in 1936, and the French 819-line system. During the 1940s René Barthélemy had already reached 1,015 lines and even 1,042 lines. On November 20, 1948, François Mitterrand, the then Secretary of State for Information, decreed a broadcast standard of 819 lines developed by Henri de France; broadcasting began at the end of 1949 in this higher definition format. It was used in France by TF1, and in Monaco by Tele Monte Carlo. Some 819-line TV sets ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
625 Lines
625-line (or CCIR 625/50) is a late 1940s European analog standard-definition television resolution standard. It consists of a 625-line raster, with 576 lines carrying the visible image at 25 interlaced frames per second. It was eventually adopted by countries using 50 Hz utility frequency as regular TV broadcasts resumed after World War II. With the introduction of color television in the 1960s, it became associated with the PAL and SECAM analog color systems. A similar 525-line system was adopted by countries using 60 Hz utility frequency (like the US). Other systems, like 375-line, 405-line, 441-line, 455-line and 819-line existed, but became outdated or had limited adoption. The modern standard-definition digital video resolution 576i is equivalent and can be used to digitize an analogue 625-line TV signal, or to generate a 625-line compatible analog signal. History At the CCIR Stockholm Conference in July 1948 a first 625-line system with an 8 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Band III
Band III is the name of the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 174 to 240 megahertz (MHz). It is primarily used for radio and television broadcasting. It is also called high-band VHF, in contrast to Bands I and II. Broadcast Television North America The band is subdivided into seven channels for television broadcasting, each occupying 6 MHz. Europe European Band III allocations vary from country to country, with channel widths of 7 or 8 MHz. The standard channel allocations for European countries that use System B with 7 MHz channel spacing are as follows: The Irish (8 MHz) system is shown below. Oceania Australia has allocated 8 channels in Band III for digital television, each with 7 MHz bandwidth. Russia and other former members of OIRT Russian analog television is transmitted using System D with 8 MHz channel bandwidth. Radio The band came into use ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Band II
Band II is the range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum from 87.5 to 108.0 megahertz (MHz). Radio Band II is primarily used worldwide for FM radio broadcasting. Broadcast television Usage in Russia and in other former members of OIRT In the former Soviet Union and other countries-members of OIRT The International Radio and Television Organisation (official name in French: Organisation Internationale de Radiodiffusion et de Télévision or OIRT (before 1960 International Broadcasting Organization (IBO), official name in French: ''Organ ..., frequencies from 76 MHz to 100 MHz were designated for broadcast television usage. Considering 8 MHz channel bandwidth used by the Russian analog television system ( System D), the following television channels had been defined: Broadcast television channels 1 and 2 are assigned to VHF I band, channels 6 to 12 are assigned to VHF III band. Starti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Band I
Band I is a range of radio frequencies within the very high frequency (VHF) part of the electromagnetic spectrum. The first time there was defined "for simplicity" in Annex 1 of "Final acts of the European Broadcasting Conference in the VHF and UHF bands - Stockholm, 1961". Band I ranges from 47 to 68 MHz for the European Broadcasting Area, and from 54 to 88 MHz for the Americas and it is primarily used for television broadcasting in compliance with ITU Radio Regulations (article 1.38). With the transition to digital TV, most Band I transmitters have already been switched off. Television broadcasting usage Channel spacings vary from country to country, with spacings of 6, 7 and 8 MHz being common. In the UK, Band I was originally used by the BBC for monochrome 405-line television; likewise, the French former 455-line (1937–1939) then 441-line (1943–1956) transmitter on the Eiffel Tower in Paris, and some stations of the French monochrome 819-line system used Band I. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stockholm
Stockholm (; ) is the Capital city, capital and List of urban areas in Sweden by population, most populous city of Sweden, as well as the List of urban areas in the Nordic countries, largest urban area in the Nordic countries. Approximately 1 million people live in the Stockholm Municipality, municipality, with 1.6 million in the Stockholm urban area, urban area, and 2.5 million in the Metropolitan Stockholm, metropolitan area. The city stretches across fourteen islands where Mälaren, Lake Mälaren flows into the Baltic Sea. Outside the city to the east, and along the coast, is the island chain of the Stockholm archipelago. The area has been settled since the Stone Age, in the 6th millennium BC, and was founded as a city in 1252 by Swedish statesman Birger Jarl. The city serves as the county seat of Stockholm County. Stockholm is the cultural, media, political, and economic centre of Sweden. The Stockholm region alone accounts for over a third of the country's Gros ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System A
CCIR System A was the 405-line analog broadcast television system adopted in the UK and Ireland. System A service started in 1936 and was discontinued in 1982 in Ireland and 1985 in Britain. Specifications Some of the important specs are listed below. * Frame rate: 25 Hz * Interlace: 2/1 * Field rate: 50 Hz * Lines per frame: 405 * Line rate: 10.125 kHz * Visual bandwidth: 3 MHz * Vision modulation: AC3 positive * Preemphasis: none * Sound modulation: A3 * Sound offset: -3.5 MHz * Channel bandwidth: 5 MHz A frame is the total picture. The frame rate is the number of pictures displayed in one second. But each frame is actually scanned twice interleaving odd and even lines. Each scan is known as a field (odd and even fields.) So field rate is twice the frame rate. In each frame there are 405 lines (or 202.5 lines in a field.) So the line rate (line frequency) is 405 times the frame frequency or 405×25=10,125 Hz. The video bandwidth w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
567-line Television System
The 567-line television system was an experimental late 1940s proposal by Philips of the Netherlands for a European television system, with some test transmissions being made from Eindhoven. The first mention of the system appeared in an article from 1938, published in the Philips' technical bulletin, on a transportable demonstration TV station, running an at 50 fields (25 frames) per second, but no more details were provided. Most of the technology was to be borrowed from the American 525-lines system, the difference being the reduction of horizontal scan frequency from 15,750 to 14,175 Hz. This would have meant that the American sound carrier frequency of 4.5 MHz above the picture carrier would have also been the standard for Europe, and hence a lot more common worldwide. By 1950 some 567-line television sets were built and distributed to Philips employees for home testing. The 567-line system was proposed for international use but never adopted. Russia Russia, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
