Methods and Equipment Techniques for Multiline VITS Insertion in TV Relays

Vertical interval test signal (VITS) insertion has now become a widely adopted means of on-line testing and monitoring of TV signal transmissions. In a network of relay links interconnecting a number of different user organizations, different functions of VITS must be provided, depending on the user and purpose of the inserted signals. To provide the required flexibility of operation, a VITS insertion unit has been developed by means of which up to eight different test signals may be inserted and/or replaced. To accommodate varying operational requirements, the insertion line switching sequence is controlled by digital insertion program logic, prewired on a plug-in card which may readily be exchanged. — Integrated with the equipment is a sampled automatic gain control system which uses an inserted level reference waveform to provide the level adjustment criterion. Synchronizing and blanking signal regeneration is also provided, but on a substantially line-by-line basis, thus allowing a number of VITS insertion units to be operated in cascade. To protect the TV signal transmission from being interrupted by a malfunction of the insertion unit, an extensive fault testing routine is built into the VITS unit. In the event of equipment failure, an automatic bridging of the insertion unit by electromechanical switches takes place.

Print ISSN

0361-4573

Published

1966-02

Content type

Original Research

DOI

10.5594/J07727