Automatic Sound-Quality Control During Program Transmission.

For TV transmission installations, the insertion test signals which have been used in recent years, have proved to be successful. Considerations regarding rationalization and automation must include, in the same way, also the automatic quality control of the transmission of the sound component. The different conditions for sound require another technique. The criterion for supervision is the change of the sound signal itself. Unlike the case of the insertion test signals, the reference value, which is defined as the signal at the point of origin, here changes with the current program signal. It must, therefore, be transmitted to the supervisory point. For this purpose in the case of television transmission it is possible to utilize the insertion data line, whose capacity has so far only been partially used. For sound transmission equipment there is the possibility of transmitting these data in the AF band below the threshold of audibility. The paper explains the technique and the possibilities for indicating level faults, interruptions, impairments of the signal-to-noise ratio, interchanges of program, etc.