8VSB

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8VSB is the 8-level vestigial sideband modulation method adopted for ATSC standard of digital television in the USA. There are also the similar modulations 2VSB, 4VSB, and 16VSB.

There has been a continuing lobby for changing the modulation for ATSC to COFDM instead, the way DVB-T is transmitted in Europe, and ISDB-T in Japan. However, the FCC has continued to assert that 8VSB is the better modulation for use in U.S digital television broadcasting. In 2000, it refused a petition for rulemaking requesting the change. Because of continued adoption of the 8VSB based ATSC standard in the US, a switch to COFDM is now unlikely.

In 2001, a technical report compiled by the COFDM Technical Group concluded that COFDM did not offer any significant advantages over 8VSB.

The debate over 8VSB vs COFDM modulation is still ongoing. Proponents of COFDM argue that it resists multipath far better than 8VSB. Early 8VSB DTV (digital television) receivers often had difficulty receiving a signal in urban environments. However, newer 8VSB receivers are far better at dealing with multipath. Moreover, 8VSB modulation requires less power to transmit a signal the same distance. In less-populated areas, 8VSB often pulls ahead of COFDM because of this. In urban areas, however, COFDM still offers better reception than 8VSB.