Digital Transmission of Two Television Sound Channels in Horizontal Blanking

The conventional way of transmitting television sound information on subcarriers leads to a number of difficulties in satellite communications systems using frequency modulation, because of the limited power available. In particular, when high-quality sound is required, modulation products can only be avoided by going to large bandwidths and high power compared with the actual picture transmission — and this is expensive. A method has been found for transmitting two high-quality (15-kHz bandwidth and better than 60-dB SNR) sound signals with no mutual interference between sound and video signals. No additional RF bandwidth and little additional power is required. The technique involves using a part of the line-blanking interval after shortening the synchronizing pulse. The sound signals are sampled and companded to a given number of bits in a non-return-to-zero code. At the receiving end the pulses are stored, decoded and read out with the original sampling frequency. After passing through a low-pass filter, the signals are available in the original position. Tests have been promising, and a practical application seems possible soon.

Print ISSN

0361-4573

Published

1975-02

Content type

Information

DOI

10.5594/J13405