Testing of Television Transmission Channels with Vertical Interval Test Signals

The choice and use of test signals for in-service testing of video transmission facilities during the vertical interval (VITS) are based on several considerations. The sine-squared pulse, having a half-amplitude duration of 1/8 μs, often called a T pulse, is not a good choice for the quality rating of a television channel. Computed results from transmission response of actual facilities and echo-rating theory show that this signal may fail to detect poor channels and will on occasion indicate that a good channel is bad. The T pulse correlates poorly with the results of subjective tests. Alternative signals analyzed as to their spectrum and application include the 2T pulse, a step function having a controlled rise time and the 20T modulated pulse for evaluating the color-carrying capabilities of a channel. On the basis of results of measurements made on operating transmission systems the next steps are recommended in the development of an optimum set of vertical interval test signals.

Print ISSN

0361-4573

Published

1968-08

Content type

Original Research

DOI

10.5594/J06983