Experimental digital stereo sound with terrestrial television: Field tests from Wenvoe, October 1983

An experimental digital system to carry two high quality sound channels with the existing terrestrial television transmission System I was devised. This experimental system uses a 4-phase d.p.s.k. modulated second sound carrier spaced at about 6.55 MHz above the vision carrier and at a level of 20 dB below it. Within the spectrum space available a data rate of about 700 kbit/s can be provided, which is capable of carrying a stereo sound pair of signals, or two independent sound signals. The existing analog f.m. sound carrier at 6 MHz above the vision carrier is retained to maintain compatibility with existing receivers, but is slightly reduced in level to 10 dB below the vision carrier in order to avoid picture patterning due to beats between the sound carriers. Over-air field tests of the experimental system were conducted out of normal program hours from the BBC-2 transmitter and its associated rebroadcast relay stations.