Television video synchronization signal monitoring system and method for cable television system

摘要

A cable television system provides television signals in multiple predefined television signal formats. Each television has a multi-standard receiver for receiving television signals in those predefined television signal formats. Hidden behind each television, or elsewhere out of view of the user, is a converter coupling the respective television to a transmission cable. The only connection from the converter to the television is a cable connected to the television's cable or antenna input port. Each television includes a raster scan CRT and CRT control circuitry that controls the raster scan sweep pattern of the electron beams generated by the CRT. The CRT control circuitry includes a horizontal scan synchronization circuit that synchronizes each horizontal sweep of the CRT electron beams with a horizontal synchronization signal in the received television signal, and generates a distinctive transient voltage signal at the beginning of each horizontal sweep of the CRT electron beams. External to the converter box is a horizontal sweep pickup antenna suitable for positioning proximate the monitored television. Internal to the converter box is a filter that extracts the horizontal synchronization component of the television signal on the channel selected by the user. A synchronization signal comparator compares the extracted horizontal synchronization component of the selected television signal with the signals, if any, received from the antenna, and outputs a result signal indicating whether the television is both turned on and tuned so as to receive the selected television signal.