Vestigial Sideband modulation – an established modulation technique which is used in the RF (radio frequency) transmission subsystem of the ATSC(1) Digital Television Standard. The 8-VSB system has eight discrete amplitude levels supporting a payload data rate of 19.28 Mb/s in a 6 MHz TV channel. There is also a high data rate mode – 16 VSB – designed for CATV (cable television) and supporting a payload of 38.57 Mb/s.
Things move on; E-VSB, Enhanced-VSB, was approved by ATSC in 2004 as an amendment to the A/53C DTV Standard as an optional transmission mode with additional forward error correction coding layers to help reception under weaker signal conditions. This was responding to the wishes broadcasters for more flexibility in DTV. E-VSB allows broadcasters to trade-off data rate for a lower carrier-to-noise threshold for some services, e.g. “fall back” audio, and targeted at receivers with indoor antennas, non-realtime transmissions of file-based information, and more.