Method and apparatus for remote synchronous switching of video transmitters

A synchronous switching apparatus for a television system comprising a plurality of transmitters for transmitting a composite video signal, each transmitter incorporating an individually allotted identification code;

• a receiver for receiving said composite video signal;
• and at least one transmission line for transmitting and receiving information between said transmitters and said receiver,
• said receiver including a circuit for generating identification code signals commensurate with the individually allotted identification codes of respective transmitters and transmitting a respective identification code signal to said transmitters through said transmission line, a circuit for generating an external synchronizing signal, a circuit for transmitting said external synchronizing signal to said transmitters through said transmission line, and means for modifying the external synchronizing signal to produce a fluctuated signal transmitted to said transmitters through said transmitting line,
• each of said transmitters including a decoder means to decode said identification code signal, identification code comparison means to compare a decoded identification code signal with said individual allotted identification code and outputting a match signal or a mismatch signal, a sensor circuit for detecting a fluctuated external synchronizing signal and outputting said fluctuated signal, and a controller for switching on a composite video signal transmission whenever said match signal and said fluctuated signal are both inputted into said controller or for switching off the video signal transmission whenever said mismatch signal and said fluctuated signal are both inputted into said controller.