Rca Inc.

General Instrument Corporation

Anthony Troiano

Walter Truskalo

Henry S Landgraf

Dipakkumar R Patel

A monaural and stereo audio signal control system for use in cable-signal set-top boxes selects signal processing paths as a function of the monaural and stereo nature of the incoming audio component of the television signal and an indication as to whether the audio component is a &ldquo;clear&rdquo; or &ldquo;masked&rdquo; signal. A clear audio signal is a signal that conforms to a NTSC or BTSC standard that can be processed by a conventional television receiver while a &ldquo;masked&rdquo; signal is one in which the carrier frequency has been changed or otherwise modified so that a conventional television receiver cannot extract the audio content. A signal-processing path is provided for conventional clear monaural and stereo audio and for a masked monaural signal and for a masked stereo signal. Monaural clear and masked processing is addressed by microprocessor controlled switching in accordance with control information provided in the television signal and stereo masked processing is addressed by the presence or absence of energy corresponding to the masked stereo carrier.

Monaural and stereo audio signal control system

A voltage converter transforms a high voltage alternating current (ac) input source into a lower voltage direct current (dc) output voltage. The line frequency of the ac current switches an electronic switch to alternately reconfigure a combination of capacitors and diodes to perform energy storage and effect voltage division. The dc output voltage is approximately one half of the peak ac input voltage at no load.

Ac/dc transformerless voltage converter

Brightness control apparatus for a color video monitor employing AC coupled video output driver stages is disclosed. A keyed amplifier provides a brightness determinative output pulse with an amplitude related to the setting of a brightness control coupled to the amplifier. The brightness pulse is coupled via separately adjustable brightness tracking circuits to control inputs of video signal clamps respectively associated with each of the color video signal paths between the driver stages and an image display device.

Brightness control apparatus for a video signal processing system

A degaussing coil and a capacitance are coupled in a resonant circuit by a switch to effect degaussing of a kinescope. The capacitance is charged by a source of relatively high voltage. A control circuit controls the operation of the switch and is responsive to a change in operating voltage applied thereto for operating the switch to effect complete discharge of the capacitance in a relatively short interval.

Degaussing system arrangements

Apparatus is described for automatically depeaking the luminance signal of a television receiver under high noise conditions to improve the subjective appearance of reproduced images. Noise accompanying the luminance signal is sensed by bandpass filtering the signal and applying the filtered signal to a detector via a sampling circuit. The sampling circuit is enabled only during the horizontal blanking interval of the luminance signal to reject the active video portions of the luminance signal. The detector is of the pulse averaging type wherein pulses representative of peaks of the sampled signal above a threshold level are generated and averaged to produce a smoothed control signal that is principally representative of the noise and substantially independent of luminance signal transitions which occur during the sampling interval. The control signal is applied to a peaking control circuit in the receiver in a sense to vary the luminance signal peaking inversely with changes in the noise level whereby the luminance signal is automatically depeaked under high noise conditions.

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Princeton Junction, NJ, United States of America

Anthony Troiano