Deutsche Itt Industries Gmbh

Gerhard Gunter

Herbert Elmis

Hermannus Schat

Bernd Novotny

Dietmar Ehrhardt

Otmar Kappeler

The frequency conversion of an RF signal is performed by the 'third method' using a suitable frequency reversal which makes the frequencies of the picture carrier, the chrominance subcarrier, and at least one sound carrier appear transformed into the baseband, such that the frequencies of the transformed picture carrier and the transformed chrominance subcarrier coincide. Unavoidable differences in the signal paths of the frequency reversal result in a spurious signal which produces a temporally/locally varying moire on the screen. By means of a frequency offset, this spurious signal is transformed into a frequency range which is not found annoying by the observer, so that the moire becomes invisible. This frequency range is preferably the exact center region between two spectral lines of the horizontal frequency of the composite color signal in the baseband.

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Neuweiler-Agenbach, Germany

Gerhard Gunter