Deutsche Itt Industries Gmbh

Zenith Electronics Corporation

Heinrich Koehne

Hans-Juergen Desor

Khosro M Rabii

Herbert Elmis

Herbert Alrutz

Hermann Zibold

A video signal clamping circuit for adapting the DC level of a composite video signal to the processing range of a digital video signal processing device, includes an isolating capacitor in the analog video signal path and a controlled current source which is connected to a floating isolating-capacitor terminal and charges or discharges the isolating capacitor solely by means of a positive or negative clamping current, with the value and sign of the clamping pulses being digitally controlled by a comparator circuit which compares predetermined reference values of the composite video signal with mode-dependent comparison values.

Video signal clamping circuit

An apparatus and method for generating a modified video signal consisting of a correction signal and a video input signal. The correction signal is derived from a digitized video input signal by at least a frequency-band limiter and an amplitude limiter. The video input signal is delayed by the processing time of the correction signal before the two signals are combined. To avoid unwanted harmonics the amplitude limiter uses a transfer function which can be exactly described by a rational integral function of the nth degree,

Apparatus including amplitude limiter and associated method for

A limiter circuit responds to an input signal which has a plurality of frequencies within a given band. The input signal is split up into two frequency ranges by means of a low pass filter for one range and a high pass filter for a second range. The output of the low pass filter is directed to a first limiter while the output of the high pass filter is directed to a variable notch filter. The outputs from the first limiter and the notch filter are added together to provide a sum signal. The sum signal is applied to a second limiter which performs limiting strictly according to the amplitude. The outputs of the second limiter signal provide the desired signal and a control signal to determine how often the second limiter is limiting. The control signal varies the attenuation of the notch filter. In this manner frequencies, within a selective range and which will be otherwise effected by the spurious frequencies generated during limiting, are reduced.

Signal limiting apparatus having improved spurious signal performance

Two-line comb filtering with spatial mixing

Growing community of inventors

Voerstetten, Germany

Heinrich Koehne