Video testing techniques in television broadcasting

A television video transmission system is basically a waveform transmission system. The prime objective is the preservation of the waveforms of signals on their journey from the camera to the home receiver. It is inevitable that some distortion of the signal occur in any practical transmission path. The amount of distortion which is permissible is based not on physical measurements alone but on viewing tests by critical observers. Those physically measurable characteristics in which large variations cause no detectable difference in the quality of the received picture may be permitted large tolerances, while those to which the picture quality is particularly sensitive are permitted only small tolerances.