US Patent 7218356 System and method for inductive line synchronization

A synchronization signal generating apparatus and method in which an input circuit is inductively coupled to an alternating current signal line. The input circuit generates a rectified signal. A switch has a switch input and a switch output in which the switch input is electrically connected to the input circuit and is enabled when the voltage of the rectified signal is greater than a predetermined voltage and is disabled when the rectified signal voltage is less than the predetermined voltage. A pulse generating circuit has a pulse generating circuit input and a pulse generating circuit output. The pulse generating circuit input is electrically connected to the switch output. The pulse generating circuit generates a pulse each time the switch is enabled. The synchronization signal generating apparatus is used in a synchronized television display system to signal a video switch to switch the video signal generated by a camera to a monitor based on the occurrence of the synchronization signal.