U.S. Philips Corporation

Hans-Jurgen Kuhn

Ulf H Buhse

In a multi-standard television receiver in which a picture signal contained in a television signal and modulated on a picture carrier is converted to a picture signal intermediate frequency, and a stereo sound signal or two-tone signal contained in the television signal and modulated on two sound carriers is converted to two first sound signal intermediate frequencies, it is ensured for possibly simple filtering of the sound signals, also at different frequency spacings between the picture carrier and the sound carriers, that two sound signal filters (8, 9) having a fixed, predetermined filter central frequency are provided for filtering the stereo sound signal, and that frequency shift circuitry (6) is provided which, in dependence upon the frequency spacing between the picture carrier of the television signal and its sound carriers, shifts the picture carrier contained in the picture signal converted to the IF position to such a frequency that the sound IF signals of the first sound intermediate frequencies mixed with this shifted picture carrier occur at two second sound signal intermediate frequencies which are filtered by the sound IF filters (8, 9).

Multi-standard television receiver

For an integratable FM demodulator which has an optimal noise behavior and does not require any balancing, the demodulator includes a marker pulse generator (2) having an integrator (22) which is succeeded by a comparator (23), while at the start of each positive and/or negative edge of the limited FM signal, a marker pulse is started and one of a first and second reference signals is applied to the integrator input until a predetermined edge of the reference clock signal appears, and the first and a second reference signals are subsequently applied alternately to the integrator input in dependence upon a reference clock signal applied to the marker pulse generator, the two reference signals being applied to the integrator input during the desired period of time of the marker pulse, each time during equal overall time intervals, and a comparison voltage occurring at the integrator output at the end of the desired period of time, which comparison voltage is detected by the comparator (23), whereupon the started marker pulse is ended.

FM demodulator

A processing section for a television receiver for processing stereo/dual sound signals having a first sound carrier modulated by a first sound signal, and a second sound carrier modulated both by a second sound signal and by a pilot signal which, in turn, is modulated by a stereo/dual sound identifying signal. The processing section does not require a reference frequency from the synchronizing or intermediate frequency portion of the television receiver for recovering the pilot signal, but, rather, uses the pilot signal to control an oscillator in a phase-locked loop which loop is used to generate a signal for down-converting the frequency range of at least the modulated second sound carrier thereby obviating the need for expensive, precision filtering components.

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Buchholz, Germany

Hans-Jurgen Kuhn