The Broadcasting House-Crystal Palace television link

The initial requirement for the Broadcasting House-Crystal Palace Television link is for one channel in each direction, but it is likely that a second channel will be needed later. The transmission of two programmes over a single tube would make 0.975 in coaxial cable economic over this distance of 9 miles and would permit transmission between terminals without intermediate equipment. To meet the need of good performance with simple low-cost equipment, a double-sideband system with amplitude modulation has been developed. To allow for later development, e.g. a wider-band channel for colour, the carrier frequency of the monochrome channel has been placed at 15 Mc/s. In the transmitting terminal the video signal is translated into the band for transmission over the cable, and in the receiving terminal the incoming signal is corrected for the loss, attenuation and delay distortions which occur in transmission, and the video signal is recovered. The performance of the link is given in terms of the measured amplitude and differential delay characteristics, transient response, linearity and signal/noise ratio.