8VSB
8VSB is the modulation method used for broadcast in the ATSC digital television standard. 8VSB modulation is used primarily in North America. 8VSB is an 8-level vestigial sideband modulation that converts a binary stream into an octal representation by amplitude modulating a sinusoidal carrier to one of eight levels.
- ATSC is the Government "Standard" for the Digital (RF) Broadcast Signal
- 8VSB is the name of the modulation standard used in ATSC Systems
The digital transition in the United States completed June 12, 2009 was a move from NTSC analog to ATSC, a way of transmitting digital over analog. A key part of the new ATSC specification is that it supports MPEG-2 encoded video and AC3 encoded audio.
The 8VSB modulation standard is well suited for over-the-air (OTC) transmission because it contains error correction to compensate with distortions that can occur in the air. 8VSB is capable of transmitting three bits (23=8) per symbol by amplitude modulating a sinusoidal carrier to an intermediate frequency. The resulting signal is then band-pass filtered with a Nyquist filter to remove redundancies in the side lobes, and then again modulated to the broadcast frequency.
- 8VSB modulation is used for OTC and QAM modulation is used for cable TV in North America.
In the 6 MHz (megahertz) channel used for broadcast ATSC, 8VSB carries a symbol rate of 10.76 Mbaud, a gross bit rate of 32 Mbit/s, and a net bit rate of 19.39 Mbit/s of usable data.
