A television master switcher

Abstract

A survey is made of the standard methods at present in use for switching video signals: the simple mechanical switch, electromechanical relays, and switching systems using thermionic relays. A method of video selection is then described in which the switch elements are made up of semi-conductor diodes. Both master control room and studio type switchers are discussed. Reference is made to current development work in which transistorized pulse generators are being used to achieve vision switching between successive frames of the television waveform.