Some aspects of television transmission over long distance cable links

摘要

An outline of the basic properties of 0.375 in. diameter coaxial cable and the combined or alternative multi-channel telephony/television systems based on it is given. Most of the required transmission limits for such systems have now been agreed internationally and a ????????hypothetical reference circuit???????? evolved for which such limits can be stated. Although limits have tended to be agreed by national experiments on the various television systems, two basic subjective laws, the Weber-Fecliner law and Ricc???????2's law, on which limits must ultimately be based, are illustrated and discussed. Television transmission is fundamentally a waveform matter but for design purposes it is necessary to use frequency responses. The paper describes two simple guides to estimating these: (1) by reference to two simple minimum phase networks, and (2) by an extension of the paired-echoes method. The advantages of using a reduced carrier level are briefly pointed out and a number of synchronizing systems reviewed.