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B-MAC
B-MAC is a form of analog video encoding, specifically a type of Multiplexed Analogue Components (MAC) encoding. MAC encoding was designed in the mid 80s for use with Direct Broadcast Satellite systems. Other analog video encoding systems include NTSC, PAL and SECAM. Unlike the FDM method used in those, MAC encoding uses a TDM method. B-MAC was a proprietary MAC encoding used by Scientific-Atlanta for encrypting broadcast video services; the full name was "Multiple Analogue Component, Type B". B-MAC uses teletext-style non-return-to-zero (NRZ) signaling with a capacity of 1.625 Mbit/s. The video and audio/data signals are therefore combined at baseband. * Both PAL (626/50) and NTSC (525/60) versions of B-MAC were developed and used. User base (PAL/NTSC zones) * This system was used in South Africa and Australia (for TVRO until 2000). * B-MAC was used for satellite broadcasts of the American Forces Radio and Television Service from the early 1980s until 1996-1997 when the ana ... [...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] |
HD-MAC
HD-MAC (High Definition Multiplexed Analogue Components) was a broadcast television standard proposed by the European Commission in 1986, as part of Eureka 95 project. It belongs to the MAC - Multiplexed Analogue Components standard family. It is an early attempt by the EEC to provide High-definition television (HDTV) in Europe. It is a complex mix of analogue signal (based on the Multiplexed Analogue Components standard), multiplexed with digital sound, and assistance data for decoding (DATV). The video signal (1250 lines/50 fields per second in 16:9 aspect ratio, with 1152 visible lines) was encoded with a modified D2-MAC encoder. HD-MAC could be decoded by normal D2-MAC standard definition receivers, but no extra resolution was obtained and certain artifacts were visible. To decode the signal in full resolution a specific HD-MAC tuner was required . Naming convention The European Broadcasting Union video format description is as follows: width x height can type: i or p/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D-MAC
Among the family of MAC or Multiplexed Analogue Components systems for television broadcasting, D-MAC is a reduced bandwidth variant designed for transmission down cable. * The data is Bipolar encoding, duobinary coded with a data burst rate of 20.25Mbit/s so that 0° as well as ±90° phasors are used. * D-MAC has a bandwidth of 8.4 MHz versus 27 MHz for C-MAC. * Most cable systems work on EBU 7 MHz channel spacing, so this approach did not work universally. * D-MAC's bandwidth problems were later fixed by D2-MAC. D2-MAC: A fix for D-MAC D-MAC consumed too much bandwidth for many applications, so D2-MAC was designed for European cable TV systems. Luminance and chrominance MAC transmits luminance and chrominance data separately in time rather than separately in frequency (as other analog television formats do, such as composite video). Audio and scrambling (selective access) * Audio, in a format similar to NICAM was transmitted digitally rather than as an FM sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A-MAC
In television electronics, A-MAC carries digital information: sound, and data-teletext on an FM subcarrier at 7 MHz. Since the vision bandwidth of a standard MAC signal is 8.4 MHz, the horizontal resolution on A-MAC has to be reduced to make room for the 7 MHz carrier. ''A-MAC has not been used in service.'' Technical details MAC transmits luminance and chrominance data separately in time rather than separately in frequency (as other analog television formats do, such as composite video). Audio and Scrambling (selective access) * Audio, in a format similar to NICAM was transmitted digitally rather than as an FM subcarrier. * The MAC standard included a standard scrambling system, EuroCrypt, a precursor to the standard DVB-CSA encryption system. TV transmission systems * Analog high-definition television systems * PAL, what MAC technology tried to replace * SECAM, what MAC technology tried to replace * A-MAC * B-MAC * C-MAC * D-MAC * E-MAC * S-MAC * D2-MAC ... [...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] |
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] |
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] |
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] |
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] |
D2-MAC
D2-MAC is a satellite television transmission standard, a member of Multiplexed Analogue Components family. It was created to solve D-MAC's bandwidth problem on European cable systems. * D2-MAC uses half the data rate of D-MAC * D2-MAC has a reduced vision bandwidth, about 1/2 that of D-MAC. * D2-MAC retains most of the quality of a D-MAC signal—but consumes only 5 MHz of bandwidth. Technical details MAC transmits luminance and chrominance data separately in time rather than separately in frequency (as other analog television formats do, such as composite video). Audio and Scrambling (selective access) * Audio, in a format similar to NICAM was transmitted digitally rather than as an FM sub-carrier. * The MAC standard included a standard scrambling system, EuroCrypt, a precursor to the standard DVB-CSA encryption system. History and politics MAC was developed by the UK's Independent Broadcasting Authority (IBA) and in 1982 was adopted as the transmission format for the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
E-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] |
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