What provisions have been made for data broadcasting in the ATSC DTV system?
The ATSC has developed a Data Broadcasting Standard, document A/90, which defines protocols for data transmission over the digital television system. The standard supports data services that are both TV program related and non-program related. Applications may include enhanced television, webcasting, and streaming video services. Data broadcasting receivers may include PCs, televisions, set-top boxes, or other devices. The standard provides mechanisms for download of data, delivery of datagrams, and streaming data.
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What is meant by "coupling" as it relates to DTV data broadcasting?
Data broadcasting applications targeted to consumers can be classified by the degree of coupling to the normal TV programming as follows. Tightly coupled data are intended to enhance the TV programming in real time. The viewer tunes to the TV program and receives the data enhancement along with it. Loosely coupled data are related to the program, but are not closely synchronized with it in time. For example, an educational program might send along in the broadcast some supplementary reading materials or self-test quizzes. Non-coupled data are typically contained in separate "data-only" virtual channels. They may be data intended for real-time viewing, such as a 24-hour news headline or stock ticker service.
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Where can I find additional information on data broadcasting?
The ATSC data broadcasting system is described in the, ATSC Data Broadcast Standard, document A/90. Another document, ATSC Recommended Practice "Implementation Guidelines for the A/90 Data Broadcast Standard," document A/91, is also available. Both of these document can be downloaded from the ATSC Web site at http://www.atsc.org/standards.
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