GB994233A - Improvements in or relating to television distribution systems - Google Patents

Abstract

994,233. Television distribution systems. SIEMENS & HALSKE A.G. March 4, 1963 [March 2, 1962], No. 8490/63. Drawings to Specification. Heading H4R. In a distribution system comprising a plurality of stations each of which serves to receive a high frequency television signal and convert it to a lower frequency before distributing it over a local distribution network to a plurality of local substations, unwanted interactions between the signals carried by the different local networks are prevented by means of a synchronizing device which transmits a synchronizing signal for the low-frequency television signals to each station. Thus in one embodiment signals of identical frequencies are transmitted over telephone lines from a central source to each of the stations for use as a mixing frequency so that television signals in Bands IV or V which have been received by these stations may be converted into Band I or III signals which can then be distributed over a conventional distribution network, interference between the signals in the different networks being substantially eliminated as they are all modulated on the same frequency. In an alternative system utilizing a separate local oscillator at each station, the synchronizing device transmits control pulses which ensure that the carrier waves generated at the stations are identical in frequency.