Thomson Multimedia S.a.

Thomson Consumer Electronics S.a.

Werner Boie

Nadine Bolender

Andrew D Hackett

Michel Sonrier

Elias Bou Sleiman

Jean-Claude Chevet

The circuit for the digital filtering of IF intermediate frequency video signals comprises an A/D (analog/digital) converter and a Nyquist filter (N); an analog prefilter, suitable for selecting the desired channel, is placed upstream of the A/D converter. The Nyquist filter (N) is a digital filter placed downstream of the A/D converter, composed of two IIR filters (15, 16) placed in cascade, one (16) of these IIR filters being produced in non-causal form with spectrum conjugate to the other IIR filter (15) produced in causal form, and of an FIR filter (17) in series, for correcting the IIR filters.

Circuit for carrying out digital Nyquist filtering of IF intermediate

A digital receiver includes a mixer stage receiving a carrier signal S(t) and delivering an intermediate frequency signal S.sub.FI (t) to a demodulation stage. The mixer stage is furnished with a PLL circuit for generating a signal at a given frequency. The digital receiver further includes a phase noise digital correction stage for tapping off a noise signal .phi..sub.n (t) generated by the PLL circuit in the mixer stage and for compensating the noise signal .phi..sub.n (t) in the demodulation stage.

Device for correcting phase noise in a digital receiver

The disclosure relates to a A digital filtering system of a signal, including a calculation circuit that calculates the average increase in amplitude .DELTA.X.sub.av (n) between two samples X(n), and an 'output signal (Y(n)) circuit' that calculates a mean, weighted by a coefficient a, of the sample to be filtered X(n) and the previous sample Y(n-1) algebraically increased by said average increase in amplitude .DELTA.X.sub.av (n). The invention is applicable to digital signal processing.

Digital filtering system for signals

A video signal is applied to a kinescope having scan velocity modulation for improving picture sharpness in the vertical direction. Pictures from video signals of a type having non-interpolated and vertically interpolated lines (e.g., interlace-progressive up-converted) will tend to exhibit a significant reduction of sharpness in vertical direction. This problem is corrected by applying scan velocity modulation only to the interpolated lines of the video signal. Furthermore, the vertical deflection is restricted to horizontal structures or real vertical transitions, respectively. In order to have a high noise immunity of this sensitive processing, the resulting luminance amplitude of the shifted line as well as the vertical deflection is controlled to be strongly dependent on the current video signal (soft decision).

Scan velocity modulation system with auxiliary vertical deflection

Large format TV tubes must produce a high peak brightness in order to be acceptable to the user. This results in a large beam current in bright areas of the picture and in a subsequent defocusing of the resulting spot on the display and in a loss of the sharpness of vertical and horizontal transitions. The apparent sharpness of a vertical transition is gained by modifying the deflection of the TV receiver such that, at vertical transitions, the line on the bright side of the transition is deflected away from the transition region. Advantageously, the amount of vertical scan modulation corresponds to a multi-level control signal and depends on the grey levels of the transition.

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Strasbourg, France

Werner Boie