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US 4,301,475 AGranted
Combination digital-analog television switching system
AssigneeVital Industries, Inc.
InventorReginald F. H. McCoy
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AssigneeVital Industries, Inc.
InventorReginald F. H. McCoy
Estimating the term…
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.
A combined analog and digital switching system for video signals, comprising a source of digital video input signals, a source of analog video input signals, first video signal mixing means having at least two analog signal inputs, second video signal mixing means having at least two digital signal inputs, means for selectively supplying said analog source input signals to one input of said first mixing means and supplying an analog zero reference signal to the other input thereof, means for selectively supplying said digital source input signals to one input of said second mixing means and supplying a digital zero reference signal to the other input thereof, means for converting the digital output of said second mixing means into a corresponding analog signal, and means for adding the analog output of said first mixing means to the output of said converting means to provide a composite analog video output signal.
A combined analog and digital video input signal switching system, comprising analog mixing means having first and second analog inputs, digital mixing means having first and second digital inputs, means for selectively connecting digital video input signals to one digital input of said digital mixing means and an analog reference signal to the corresponding input of said analog mixing means, means for selectively connecting analog video input signals to one analog input of said analog mixing means and a digital reference signal to the corresponding input of said digital mixing means, and means for combining the outputs of said analog and digital mixing means to provide a desired composite video output signal.
A combined analog and digital video input signal switching system, comprising means for developing a control signal corresponding to predetermined areas of a desired composite output image in which a digital video input signal and an analog input signal are to appear respectively, means for developing a first video output signal consisting of portions of said digital video input signal corresponding to said predetermined output image digital signal areas and a digital zero reference signal in the remaining portions thereof, means for developing a second video output signal consisting of portions of said analog video input signal corresponding to said predetermined output image analog signal areas and an analog zero reference signal in the remaining portions thereof, and means for combining said first and second video output signals to provide a composite video output signal corresponding to said desired output image.
A combined analog and digital video input signal switching system, comprising a digital video signal mixer having first and second digital input buses, an analog video signal mixer having first and second analog input buses, first and second digital input signal buses associated with said digital mixer, first and second analog input signal buses associated with said analog mixer, means for supplying a digital video input signal to said first digital input signal bus and an analog zero reference signal to said first analog input signal bus, means for supplying an analog video input signal to said second analog input signal bus and a digital zero reference signal to said second digital input signal bus, means for selectively connecting said first digital input signal bus to one of said digital mixer input buses and simultaneously connecting said first analog input signal bus to one of said analog mixer input buses, means for selectively connecting said second analog input signal bus to the other one of said analog mixer input buses and simultaneously connecting said second digital input signal bus to the other one of said digital mixer input buses, and means for combining the outputs of said digital mixer and said analog mixer to provide a desired composite video output signal comprising portions of both said digital video input signal and said analog video input signal.
A combined analog and digital video input signal switching system, comprising analog mixing means having first and second analog inputs, digital mixing means having first and second digital inputs, means for selectively connecting digital video input signals to one digital input of said digital mixing means and an analog reference signal having a fixed value during active picture intervals to the corresponding input of said analog mixing means, means for selectively connecting analog video input signals to one analog input of said analog mixing means and a digital reference signal to the corresponding input of said digital mixing means, and means for combining the outputs of said analog and digital mixing means while taking into account the value of said fixed reference signals, thereby to provide a desired composite video output signal.
A combined analog and digital video input signal switching system, comprising an analog video signal path including at least one analog video signal mixer, a digital video signal path including at least one digital video signal mixer, means common to said analog signal path and said digital signal path for controlling both said analog mixer and said digital mixer, and means for combining the outputs of said analog mixer and said digital mixer to provide a composite video output signal.
An analog video input signal switching system which is adaptable to accommodate one or more digital video input signals, comprising an analog video signal path including at least one analog mixer having first and second analog inputs and a control signal input, a plurality of analog switches for selectively connecting different analog video input signals to either one of said first and second analog inputs, each of said analog switches having a control input terminal, means for supplying first control signals to said analog switch control input terminals, means for supplying second control signals to said mixer control signal input, and connections to said analog switch control input terminals and said mixer control signal inputs for establishing a digital video signal path which is parallel to said analog signal path and is controlled by said first and second control signals.
A combined analog and digital switching system for video signals, comprising first and second sources of analog video input signals, first video signal mixing means having at least two analog signal inputs, second video signal mixing means having at least two digital signal inputs, means for supplying said first and second analog source input signals to said two analog signal inputs of said first video signal mixing means, means for supplying digital zero reference signals to said two digital signal inputs of said second video signal mixing means, means for converting the digital output of said second mixing means into a corresponding analog signal, and means for adding the analog output of said first mixing means to the output of said converting means to provide a composite analog video output signal.
A combined analog and digital switching system for video signals, comprising first and second digital video input signals, first video signal mixing means having at least two analog signal inputs, second video signal mixing means having at least two digital signal inputs, means for supplying said first and second digital source input signals to said two digital signal inputs of said second video signal mixing means, means for supplying analog zero reference signals to said two analog signal inputs of said first video signal mixing means, means for converting the digital output of said second mixing means into a corresponding analog signal, and means for adding the analog output of said first mixing means to the output of said converting means to provide a composite analog video output signal.
Dependencies are inferred from the claim text.