U.S. Philips Corporation

Koninklijke Philips Corporation N.V.

Holger Moll

Axel Kattner

Holger Ernst

A filter for processing frequency signals, preferably received, particularly digital television signals is described, which filter comprises a Chebyshev filter (), a subsequent all-pass filter () and a control device (to) for controlling the Chebyshev filter () and the all-pass filter ().

Integrated DVB filter

In a frequency modulator (1) having an adjusting circuit by which frequency modulator an applied luminance signal of a color video signal that contains synchronization pulses is frequency modulated, while the chrominance signal of the color video signal is modulated on a carrier, that has a quiescent frequency if no color information is available. A capacitor is provided for an automatic mode of operation, and is charged or discharged, respectively, in dependence on the period duration of the modulator output signal and in dependence on the period duration of the quiescent frequency of the chrominance carrier. The steepness of the voltage/frequency characteristic curve of the modulator is set dependent upon the charge condition of the capacitor, while the charging-to-discharging ratio is selected such that the charge of the capacitor is maintained constant on average, if the modulator frequency is equal to a predefined nominal frequency and increases or decreases, respectively, if the modulator frequency falls short of or exceeds the nominal frequency during the synchronization pulses.

Frequency modulator comprising an adjusting circuit

A circuit arrangement for optionally amplifying one of two signals (from 2 or 6 respectively) in which at least one of the signals is supplied via a switchable signal path interruption which is inhibited when no signal is applied thereacross, and to which in this state a signal voltage is applied to both ends, which is associated with the signal to be amplified and which has already been amplified, respectively. When such a structure of a circuit arrangement is used, no damage to the circuit structure can occur, even when a signal path is interrupted in normal operation.

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Hamburg, Germany

Holger Moll