Circuit for carrying out digital Nyquist filtering of IF intermediate frequency signals
AssigneeThomson multimedia S.A.
InventorsWerner Boie, Elias Bou Sleiman
Life of this patent
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Abstract
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.
Claims16
A circuit for digital filtering intermediate frequency (IF) video signals having an analog to digital (A/D) converter and a Nyquist filter, comprising:
- an analog prefilter placed upstream of said A/D converter for selecting the desired channel;
- said Nyquist filter comprising a digital filter placed downstream of said A/D converter,
- said Nyquist filter including two IIR filters coupled together in cascade,
- one of said IIR filters being produced in non-causal form and the other IIR filter being produced in causal form;
- and
- said Nyquist filter further including an FIR filter coupled in series to said cascade IIR filters for correcting said IIR filters.
Dependencies are inferred from the claim text.