ATSC
ATSC, developed by the Advanced Television Systems Committee, is the North American standard for digital terrestrial television. The baseband signal is the MPEG-2 transport stream featuring MPEG-2 video and Dolby digital audio. SDTV and HDTV are broadcast via ATSC. The transport stream data rate is fixed at 19.39 Mbit/s. ATSC is currently used in the USA, Canada, Mexico and South Korea.
The structure of ATSC is completely different from that of DVB-T. ATSC has the following main features:
- Concatenated Reed-Solomon (188, 208) and Trellis error protection, with interposed short Forney interleavers in the channel coder
- 8VSB single-carrier modulation mode with eight-level vestigial sideband filtering
- Pilot carrier at the former band center of the vestigial sideband mode.
The output signal in the modulator is an eight-level step signal prior to the mixing process, to which a direct voltage offset for pilot generation is added. The lower sideband is partially suppressed, in a similar way as with analog television. However, this results in a Q portion that gives the constellation diagram its typical vertically striped appearance.
Standardization proposals for optimizing ATSC, primarily with regard to SFN suitability, are currently pending; under discussion is AVSB (advanced VSB).
Advanced VSB - A Proposed Enhancemant for ATSC DTV
A-VSB FAQs
A-VSB SFN Demonstration
A-VSB Video
Frequency: VHF band III, UHF band IV, V
Modulation: 8VSB
Bandwidth: 6 MHz
Symbol rate: 10.76 Msymbol/s
Bits per symbol: 3
Net data rate: 19.39 Mbit/s
Source coding: MPEG-2 video, Dolby digital audio
