Archived Documents

Zenith and AT&T have developed an all-digital high-definition television (HDTV) simulcast system that combines powerful video compression technology and a unique simulcast transmission system. The system, called "Digital Spectrum Compatible" (DSC), provides full high-definition resolution -- perceived to be equal to the studio original -- even after compressing the wide bandwidth signal into a 6- MHz channel. The system digitally transmits the compressed signal on currently unusable or ''Taboo'' television channels with only minimal interference to or from NTSC channels.

The DSC-HDTV system's high-performance compression and RF transmission technologies provide transparent picture quality utilizing a maximum video data rate (up to 17 megabits per second, Mb/s) and provide noise-free and ghostfree terrestrial broadcast reception throughout a broad service area. This area will be comparable to or, in many cases, greater than the current NTSC service area, even though transmitter power can be reduced by more than 90% from the power required for NTSC transmissions.

In addition to its unique performance capabilities for terrestrial broadcasting, the DSC-HDTV system is compatible with other media, including cable, satellite, studio video tape recorders, home video cassette recorders, video disc and fiber. Because the complete high-definition television signal (including video, chroma, audio, ancillary signals, decoder address, and encryption information) is encoded into one 6-MHz bandwidth signal, the system can be simply adapted to other media using current electrical and mechanical technologies. (See Section 8.)

The system's 787.5-line progressive scanning format eliminates artifacts of interlaced systems, provides full motion rendition (critical for sports and other fast-action programming) and promotes HDTV compatibility with current and future computer and digital communications technologies. Progressive scanning plus square pixels and unique compression technology make the DSC-HDTV system ideally suited for interconnectivity, extensibility, scalability and other computerrelated considerations. (See Section 9.)

This document details the System Specification of the Grand Alliance HDTV System, and is intended to form the basis for the documentation of the proposed standard. It is comprised of the documents that have evolved from the work of the Grand Alliance Specialist Groups with the guidance and cooperation of the Advisory Committee on Advanced Television Services (ACATS) Experts Groups. This system specification document also details the prototype hardware, currently under construction. This prototype implementation will be delivered to the Advanced Television Test Center (ATTC) for verification of the performance of the proposed Grand Alliance HDTV system standard.

This document defines a Standard for System Information (SI) and Program Guide (PG) data compatible with digital multiplex bit streams constructed in accordance with ISO/IEC 13818-1 (MPEG-2 Systems). The document defines the standard protocol for transmission of the relevant data tables contained within packets carried in the Transport Stream multiplex. The protocol defined herein will be referred to as Program and System Information Protocol (PSIP). Prior to being approved as an ATSC Standard, this document was designated T3/S8-193 and later, after approval by T3, as Doc. T3-442.

This standard was prepared by the Advanced Television Systems Committee (ATSC) Technology Group on Distribution (T3). The document was approved by T3 on 22 October 1997 for submission by letter ballot to the membership of the full ATSC. The document was approved by the members of the ATSC on 23 December 1997.

For an informative description of the purpose, concepts, and tables defined in this protocol, first time readers are encouraged to start with Annex D.