TV dual channel digital sound-a precision instrument for transmitter testing

In preparation for the introduction of dual channel sound on both the ITV and Fourth Channel transmitter networks, the IBA has designed a precision instrument for testing transmitters to measure the effect on the digital sound subcarrier of distortions introduced by the transmitter. Any such distortions would degrade the digitally modulated subcarrier, thereby reducing the noise margin in receivers and consequently reducing the dual channel sound service area. In this paper, the test instrument, its measurement principles and performance are described. The detailed planning for the implementation of the dual channel sound service is described in a related paper by Wellbeloved and Kyffin (1988)