Importance

Loading Importance Indicators...

Abstract

A combined analog and digital video television signal switching system is provided in which parallel video signal paths are provided for analog and digital television signals, these paths being controlled by common control signals. When a video input signal is digital it is supplied to the digital signal path and an analog zero reference signal is supplied to the corresponding analog input in the analog signal path. When a video input signal is analog it is supplied to the analog signal path and a digital zero reference signal is supplied to the corresponding digital input in the digital signal path. The analog mixers in the analog signal path and the digital mixers in the digital signal path are each controlled by the same control signals generated by the common control equipment. If the common mixer control signals generated are in analog form they are used directly to control the analog mixers in the analog signal path and are converted to digital form for controlling the digital mixers in the digital signal path. If these common control signals are in digital form they are used directly to control the digital mixers and are converted to analog form to control the analog mixers. Conversions from digital to analog and/or from analog to digital are performed at the output of the switching system to suit the requirements (digital or analog) of subsequent equipment. When the subsequent equipment requires a digital input all digital inputs to the switching system will remain digital throughout and analog inputs will suffer only one conversion at the output of the switching system. The converse applies when the subsequent equipment requires an analog input.

Loading the Abstract Image...

First Claim