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E-VSB or Enhanced VSB is an optional enhancement to the original
ATSC Standards Advanced Television Systems Committee (ATSC) standards are an American set of standards for digital television transmission over terrestrial, cable and satellite networks. It is largely a replacement for the analog NTSC standard and, like that ...
that use the
8VSB 8VSB is the modulation method used for broadcast in the ATSC digital television standard. ATSC and 8VSB modulation is used primarily in North America; in contrast, the DVB-T standard uses COFDM. A modulation method specifies how the radio sig ...
modulation system used for
transmission Transmission may refer to: Medicine, science and technology * Power transmission ** Electric power transmission ** Propulsion transmission, technology allowing controlled application of power *** Automatic transmission *** Manual transmission ** ...
of digital television. It is intended for improving
reception Reception is a noun form of ''receiving'', or ''to receive'' something, such as art, experience, information, people, products, or vehicles. It may refer to: Astrology * Reception (astrology), when a planet is located in a sign ruled by another ...
where signals are weaker, including
fringe reception A broadcast range (also listening range or listening area for radio, or viewing range or viewing area for television) is the service area that a broadcast station or other transmission covers via radio waves (or possibly infrared light, which i ...
areas, and on portable devices such as handheld televisions or mobile phones. It does not cause problems to older receivers, but they cannot take advantage of its features. E-VSB was approved by the ATSC committee in 2004. However, it has been implemented by few stations or manufacturers. For mobile applications, ATSC suffers significant signal degradation caused by the
Doppler effect The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who d ...
. Additionally, low-power handheld receivers are usually equipped with smaller
antennas In radio engineering, an antenna or aerial is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. In transmission, a radio transmitter supplies a ...
. These have a poor
signal-to-noise ratio Signal-to-noise ratio (SNR or S/N) is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. SNR is defined as the ratio of signal power to the noise power, often expressed in de ...
, which is disruptive to digital signals. The E-VSB standard provides for Reed–Solomon error correction to alleviate the
data corruption In the pursuit of knowledge, data (; ) is a collection of discrete values that convey information, describing quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted. ...
caused by these issues. Additionally, the standard can use either the MPEG-4 AVC or VC-1
video codec A video codec is software or hardware that compresses and decompresses digital video. In the context of video compression, ''codec'' is a portmanteau of ''encoder'' and ''decoder'', while a device that only compresses is typically called an '' ...
s. As these codecs have higher video compression than the original MPEG-2, they require less bandwidth. As 8VSB lacks both
link adaptation Link adaptation, comprising adaptive coding and modulation (ACM) and others (such as Power Control), is a term used in wireless communications to denote the matching of the modulation, coding and other signal and protocol parameters to the conditi ...
and
hierarchical modulation Hierarchical modulation, also called layered modulation, is one of the signal processing techniques for multiplexing and modulating multiple data streams into one single symbol stream, where base-layer symbols and enhancement-layer symbols are sy ...
of
DVB Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) o ...
, which would allow the SDTV part of an HDTV signal (or the
LDTV Low-definition television (LDTV) refers to TV systems that have a lower screen resolution than standard-definition TV systems. The term is usually used in reference to digital TV, in particular when broadcasting at the same (or similar) resolut ...
part of SDTV) to be received even in
fringe reception A broadcast range (also listening range or listening area for radio, or viewing range or viewing area for television) is the service area that a broadcast station or other transmission covers via radio waves (or possibly infrared light, which i ...
areas where
signal strength In telecommunications, particularly in radio frequency engineering, signal strength refers to the transmitter power output as received by a reference antenna at a distance from the transmitting antenna. High-powered transmissions, such as those u ...
is low, E-VSB yields a similar benefit. However, E-VSB places a significant processing overhead on the receiver, as well as a significant transmission overhead on the broadcaster's total bitrate. These are not a problem with DVB-H.
A-VSB A-VSB or Advanced VSB is a modification of the 8VSB modulation system used for transmission of digital television using the ATSC system. One of the constraints of conventional ATSC transmission is that reliable reception is difficult or impossi ...
is a different and, , unapproved addition to ATSC, which is also designed to send programming to mobile devices, and to allow for
single-frequency network A single-frequency network or SFN is a broadcast network where several transmitters simultaneously send the same signal over the same frequency channel. Analog AM and FM radio broadcast networks as well as digital broadcast networks can operate ...
s. It is one of several proposals for
ATSC-M/H ATSC-M/H (''Advanced Television Systems Committee - Mobile/Handheld'') is a U.S. standard for mobile digital TV that allows TV broadcasts to be received by mobile devices. ATSC-M/H is a mobile TV extension to preexisting terrestrial TV broadcast ...
, the as-yet undecided standard for mobile broadcasting via ATSC.


References


See also

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ATSC-M/H ATSC-M/H (''Advanced Television Systems Committee - Mobile/Handheld'') is a U.S. standard for mobile digital TV that allows TV broadcasts to be received by mobile devices. ATSC-M/H is a mobile TV extension to preexisting terrestrial TV broadcast ...
Radio modulation modes ATSC {{tv-tech-stub