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C-MAC
C-MAC is the television technology variant approved by the European Broadcasting Union (EBU) for satellite transmissions. The digital information is modulated using 2-4PSK ( phase-shift keying), a variation of quadrature PSK where only two of the phaser angles (±90°) are used. * The data capacity for C-MAC is 3Mbit/s. * C-MAC data has to be sent to the transmitter separately from the vision. * The transmitter switches between FM (vision) and PSK (sound/data) modulation during each television line period. C-MAC variants : E-MAC E-MAC (Extended MAC) is 16:9 version of C-MAC. Originally E-MAC was designed for 15:9 pictures, it later adopted the 16:9 aspect ratio. * In E-MAC all the 4:3 information is transmitted exactly as in C-MAC so that C-MAC receivers are still compatible. * E-MAC hides extra luminance and chrominance information in the field blanking interval and parts of the line blanking interval. * E-MAC has a lower data capacity because luminance is hidden where data ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiplexed Analogue Components
Multiplexed Analogue Components (MAC) was an analog television standard where luminance and chrominance components were transmitted separately. This was an evolution from older color TV systems (such as PAL or SECAM) where there was interference between chrominance and luminance. Originally proposed in the 1980s for use on a Europe-wide Terrestrial television, terrestrial High-definition television, HDTV system, although it was never used terrestrially. However, tests have been done in France with terrestrial transmission but no commercial exploitation. Various systems were developed, collectively known as the "MAC/packet" family. In 1985 these were recommended for Satellite television, satellite and Cable television, cable broadcasts by the European Broadcasting Union, European Broadcasting Union (EBU). C-MAC, C-MAC/packet was intended for Satellite television#Direct-to-home and direct broadcast satellite, Direct Broadcast Satellite (DBS), D-MAC, D-MAC/packet was intended for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PAL And D2-MAC Transmission
Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 frames) per second, and associated with CCIR analogue broadcast television systems B, D, G, H, I or K. The articles on analog broadcast television systems further describe frame rates, image resolution, and audio modulation. PAL video is composite video because luminance (luma, monochrome image) and chrominance (chroma, colour applied to the monochrome image) are transmitted together as one signal. A latter evolution of the standard, PALplus, added support for widescreen broadcasts with no loss of vertical resolution, while retaining compatibility with existing sets. Almost all of the countries using PAL are currently in the process of conversion, or have already converted transmission standards to DVB, ISDB or DTMB. Due to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiplexed Analogue Components Transmission (simulation)
In telecommunications and computer networking, multiplexing (sometimes contracted to muxing) is a method by which multiple analog or digital signals are combined into one signal over a shared medium. The aim is to share a scarce resource - a physical transmission medium. For example, in telecommunications, several telephone calls may be carried using one wire. Multiplexing originated in telegraphy in the 1870s, and is now widely applied in communications. In telephony, George Owen Squier is credited with the development of telephone carrier multiplexing in 1910. The multiplexed signal is transmitted over a communication channel such as a cable. The multiplexing divides the capacity of the communication channel into several logical channels, one for each message signal or data stream to be transferred. A reverse process, known as demultiplexing, extracts the original channels on the receiver end. A device that performs the multiplexing is called a multiplexer (MUX), and a devi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Technology Of Television
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 th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Broadcasting Union
The European Broadcasting Union (EBU; french: Union européenne de radio-télévision, links=no, UER) is an alliance of Public broadcasting, public service media organisations whose countries are within the European Broadcasting Area or who are member states of the Council of Europe, members of the Council of Europe. , it is made up of 112 member organizations from 54 countries, and 31 associate members from a further 20 countries. It was established in 1950, and had its administrative headquarters in Geneva and technical office in Brussels. The EBU owns and operates the Eurovision (network), Eurovision and Euroradio telecommunications networks on which major television and radio broadcasts are distributed live to its members. It also operates the daily Eurovision news exchange in which members share breaking news footage. In 2017, the EBU launched the Eurovision Social Newswire, an eyewitness and video verification service. Led by Head of Social Newsgathering, Derek Bowler, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phase-shift Keying
Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication. Any digital modulation scheme uses a finite number of distinct signals to represent digital data. PSK uses a finite number of phases, each assigned a unique pattern of binary digits. Usually, each phase encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular phase. The demodulator, which is designed specifically for the symbol-set used by the modulator, determines the phase of the received signal and maps it back to the symbol it represents, thus recovering the original data. This requires the receiver to be able to compare the phase of the received signal to a reference signal such a system is termed c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chrominance
Chrominance (''chroma'' or ''C'' for short) is the signal used in video systems to convey the color information of the picture (see YUV color model), separately from the accompanying luma signal (or Y' for short). Chrominance is usually represented as two color-difference components: U = B′ − Y′ (blue − luma) and V = R′ − Y′ (red − luma). Each of these difference components may have scale factors and offsets applied to it, as specified by the applicable video standard. In composite video signals, the U and V signals modulate a color subcarrier signal, and the result is referred to as the chrominance signal; the phase and amplitude of this modulated chrominance signal correspond approximately to the hue and saturation of the color. In digital-video and still-image color spaces such as Y′CbCr, the luma and chrominance components are digital sample values. Separating RGB color signals into luma and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NICAM
Near Instantaneous Companded Audio Multiplex (NICAM) is an early form of lossy compression for digital audio. It was originally developed in the early 1970s for point-to-point links within broadcasting networks.Croll, M.G., Osborne, D.W. and Spicer, C.R. (1974), ''Digital sound signals: the present BBC distribution system and a proposal for bit-rate reduction by digital companding''. IEE Conference publication No. 119, pp. 90–96 In the 1980s, broadcasters began to use NICAM compression for transmissions of stereo TV sound to the public. History Near-instantaneous companding The idea was first described in 1964. In this, the 'ranging' was to be applied to the analogue signal before the analogue-to-digital converter (ADC) and after the digital-to-analogue converter (DAC). The application of this to broadcasting, in which the companding was to be done entirely digitally after the ADC and before the DAC, was described in a 1972 BBC Research Report. Point-to-point links NI ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Analog High-definition Television Systems
Analog high-definition television has referred to a variety of analog video broadcast television systems with various display resolutions throughout history. Pre-1940 On 2 November 1936 the BBC began transmitting the world's first public regular analog "high definition" television service from the Victorian Alexandra Palace in north London. It therefore claims to be the birthplace of television broadcasting as we know it today. The UK's 405-line system introduced in 1936 was described as "high definition"; however, this was in comparison with the early 30-line (largely) experimental system from the 1920s, and would not be considered high definition by modern standards. John Logie Baird, Philo T. Farnsworth, and Vladimir Zworykin had each developed competing TV systems, but resolution was not the issue that separated their substantially different technologies, it was patent interference lawsuits and deployment issues given the tumultuous financial climate of the late 1920s a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DVB-S
Digital Video Broadcasting – Satellite (DVB-S) is the original DVB standard for Satellite Television and dates from 1995, in its first release, while development lasted from 1993 to 1997. The first commercial applications was by Star TV in Asia and Galaxy in Australia, enabling digitally broadcast, satellite-delivered Television to the public.DVB-S was the first DVB standard for satellite, defining the framing structure, channel coding and modulation for 11/12 GHz satellite services It is used via satellites serving every continent of the world. DVB-S is used in both Multiple Channel Per Carrier (MCPC) and Single channel per carrier modes for Broadcast Network feeds as well as for direct-broadcast satellite services like Sky (UK & Ireland) via Astra in Europe, Dish Network and Globecast in the U.S. and Bell Satellite TV in Canada. While the actual DVB-S standard only specifies physical link characteristics and framing, the overlaid transport stream delivered by DVB-S is man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DVB-T
DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in February, 1998. This system transmits compressed digital audio, digital video and other data in an MPEG transport stream, using coded orthogonal frequency-division multiplexing (COFDM or OFDM) modulation. It is also the format widely used worldwide (including North America) for Electronic News Gathering for transmission of video and audio from a mobile newsgathering vehicle to a central receive point. It is also used in the US by Amateur television operators. Basics Rather than carrying one data carrier on a single radio frequency (RF) channel, COFDM works by splitting the digital data stream into a large number of slower digital streams, each of which digitally modulates a set of closely spaced adjacent sub-carrier frequencies. In the cas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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