ITU-R REPORT BT.1226 PDF

Introduction

A programme delivery control (PDC) system assists the user of broadcast services (video, sound and data) by the transmission of accompanying data signals specifically related to the programme.

A first application of PDC is in conjunction with video recording {CCIR. 1986-90a: ARD/ZDF, 1987}. Use of the system can simplify the process of data entry for selected programmes and can ensure timing on recording under the control of the broadcaster. In the first case this reduce the opportunity for errors in data entry and in the second case this compensates automatically for rescheduling of transmission times to account for unpredictable events which may delay (or occasionally advance) programmes.

Joint Interim Working Party 10-11/5 has proposed that Study Group 11 should aim at making a Recommendation on PDC to avoid a proliferation of standards. Study Group 11 has agreed with this view and a draft new Recommendation on programme delivery control systems for video recording is to be subjected to an accelerated approvals procedure during the CCIR Study Period (1990-1994).

This report describes the main characteristics required for such a system, and in particular the service requirements and functional capabilities for the video recording application. Detailed definitions and specifications for the functions, which are considered to be central and essential to the standardization of a universal PDC system, are given.

Bearing in mind the variation in transport mechanisms already employed for data broadcasting in different countries, it is to be expected that some variation in the details of implementation and coding of PDC functions will be inevitable [CCIR, 1986-90b]. the report is therefore structured to include such details as they apply to CCIR teletext systems A, B, C and D, [CCIR Recommendation 653] and other data transports in a separate annex.

Experience with services already implemented shows the need for clear rules ion how a PDC system should be operated to achieve the reaction to be intended at the receiving end. Similarly guidelines on suggested ways of implementing receiver functions in the video recorder control software may significantly improve the system performance for the user. There is therefore a need to continue the collaboration between broadcasters and industry throughout the implementation and application phases of such a system. This will be of particular benefit in ensuring the orderly introduction of specified features and of new features for which the system has a potential, but which, at service commencement, are not fully specified.