The Grass Valley Group, Inc.

Grant T McFetridge

Kevin J Shuholm

John Edward Liron

Randy K Hall

A crosstalk reduction circuit compensates for input to output capacitance coupling of each switch of a crosspoint matrix and for output to common level capacitance coupling for each integrated circuit chip that makes up the crosspoint matrix. Each input signal to the crosspoint matrix is capacitively scaled, summed and inverted to produce an 'off' isolation compensation signal, and each output signal from the crosspoint matrix is capacitively scaled, summed and inverted to produce an output isolation compensation signal. Each compensation signal is resistively scaled for each output signal, and the scaled compensation signals are subtracted from the output signals to reduce the crosstalk in the output signals.

Crosstalk reduction circuit for crosspoint matrix

A wipe-only effects apparatus has a video mixer with video input terminals for receiving respective input video signals. The mixer combines the input video signals in dependence upon a control signal received at a control input terminal of the mixer. A ramp generator a repetitive ramp signal and applies it to a control input terminal of the video mixer as the control signal. The repetitive ramp signals start at the beginning of the active picture interval of a video field and terminate at a position determined by an operator controlled knob. The transition from one video signal to the other is caused by decreasing the slope of the repetitive ramp signal to zero.

Video special effects apparatus

The color burst of a first video signal is brought into a desired phase relationship with the color burst of a second video signal by generating a first number which is representative of the phase relationship between the burst of the second video signal and a calibration reference signal and generating a second number which is representative of the phase relationship between the burst of the first video signal and the calibration reference signal. The second number is compared with the first number, and the phase of the burst of the first video signal is adjusted automatically in a manner such as to achieve a predetermined relationship between the second number and the first number.

Method and apparatus for calibrating the phase of a video signal

A matte generator for generating a video signal representative of a matte having a uniform color, has an operator interface for generating signals representing three independent variables which are sufficient to characterize a color. A processor receives the input signals and derives three numerical values from the input signals and from calibration values provided to the processor, and a quadrature modulator receives a subcarrier signal and signals representing the three numerical values and generates an encoded video signal in response thereto. The encoded video signal and a calibration signal are applied to a calibration circuit for comparing the encoded video signal and the calibration signal and providing an output signal representative of the relationship therebetween. The output signal of the calibration circuit is applied to the processor and is used to generate calibration values such that the encoded video signal is brought into predetermined relationship with the calibration signal.

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Nevada City, CA, United States of America

Grant T McFetridge