DAVIC does not suggest any particular implementation strategy for STBs. Compliance is achieved by adhering to specified hardware and software interfaces and having the capability to execute a long list of 'DAVIC applications.' DAVIC consumer terminals have some mandatory interfaces and other optional interfaces. This paper discusses the requirements in an HCT to meet the requirements set forth in DAVIC 1.0. Also suggestions are made on how to implement certain aspects ignored by DAVIC, such as compatibility with existing consumer equipment and network realities. The network interface implementation at the A1 reference point is discussed, explaining the building blocks for the front- end, tuning, demodulation and error correction of the 3 major data paths. Further processing of the high speed forward data stream in the MPEG demux and separation of the media and control data is explained. The routing of the data from the S2, S3 and S4 paths and the hardware/processing capabilities required are enumerated. Different options on implementing a cost effective and tamper proof CA system is explored. Effective ways of providing media processing, MPEG audio and video decompression and graphics processing with minimum memory and processing cycle wastage is explained. Effective performance of 'DAVIC applications' requires a certain amount of processing power and memory size. Also different types of memory are required. Several interfaces are required on the consumer side to give enhanced viewing experience a digital interactive system can provide. At the same time existing televisions and other consumer equipment will have to be supported also. This means supporting digital television and digital VCRs and home PC connections will co-exist with legacy non cable ready TVs and analog VCRs. The design has to support capabilities to expand new features and capabilities.
Ajith N. Nair,
"DAVIC compliant hardware reference platform for a cable home-communications terminal", Proc. SPIE 2917, Broadband Access Systems, (4 November 1996); doi: 10.1117/12.257325; https://doi.org/10.1117/12.257325