E-VSB
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E-VSB or Enhanced VSB is an optional enhancement[1] to the original ATSC Standards that use the 8VSB modulation system used for transmission of digital television. It is intended for use by portable devices such as handheld televisions or mobile phones.
Low power handheld receivers are usually equipped with smaller antennas. These have a poor signal-to-noise_ratio which is disruptive to digital signals. The standard can use either the AVC or VC-1 video codec. As these codecs have higher compression than the original MPEG-2, they require less bandwidth.
As 8VSB lacks true hierarchical modulation, which would allow the SDTV part of an HDTV signal to be received even in fringe reception areas where signal strength is low, E-VSB yields a similar benefit.
For mobile applications, ATSC suffers significant signal degradation caused by the Doppler effect. The E-VSB standard provides for Reed-Solomon forward error correction to alleviate the signal corruption caused by the Doppler effect.
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