U.S. Philips Corporation

Hans J Apeldoorn

Peter J Janssen

Miloslav Tryzna

TV-IF circuit comprising a balanced video signal path (A.sub.5, M, A.sub.6, VM) arranged between an IF-input (1, 1') and a video signal output (2, 2') and a balanced sound signal path (A.sub.1, A.sub.2, A.sub.7, SM) arranged between the IF-input (1, 1') and a sound signal output (3, 3'), these two paths comprising a video mixing stage (VM) and a sound mixing stage (SM), respectively for a quasi-parallel sound signal processing or an intercarrier sound signal processing. The compatability between these two modes of sound signal processing increases the range of applications compared with prior art TV-IF circuits and this is accomplished by a matrix circuit (M) comprising a balanced, non-inverting (5, 5') and a balanced, inverting (4, 4') input, as well as a balanced output (6, 6'), the matrix circuit (M) being included via the non-inverting input (5, 5') and the output (6, 6') in one (A.sub.5, M, A.sub.6, VM) of said two signal paths (A.sub.5, M, A.sub.6, VM or A.sub.1, A.sub.2, A.sub.7, SM) between the IF-input (1, 1') and a signal input (7, 7') of the mixing stage (VM) in this signal path (A.sub.5, M, A.sub.6, VM), the other signal path (A.sub.1, A.sub.2, A.sub.7 SM) between the IF-input (1, 1') and a signal input (10, 10') of the mixing stage (SM) in the last-mentioned signal path (A.sub.1, A.sub.2, A.sub.7, SM) being connected to the balanced, inverting input (4, 4') of the matrix circuit (M) and comprising between the IF-input (1, 1') and the matrix circuit (M) a balanced first pair of terminals (9, 9') which may optionally be shortcircuited, remain open-circuited or for connecting therebetween a resonant circuit (FSC) having a resonant frequency which corresponds to a sound carrier frequency of the TV-IF signal applied to the IF-input.

TV-IF Circuit

Television receiver for receiving a picture carrier whose amplitude is modulated with a video signal and a sound carrier whose frequency is modulated with an audio signal. The sound intercarrier signal produced by a mixing circuit is divided by a detected amplitude-modulated interference have, a signal of a substantially constant amplitude being thus produced. Consequently, a limiter preceding the frequency demodulator is not required.

Television receiver for receiving a picture carrier whose amplitude is

In a television receiver comprising a synchronous demodulator having a push-pull output behind which an emitter-coupled transistor pair is connected for suppressing whiter-than-white noise signals, a signal can be obtained from the collector circuit of one of the transistors of the transistor pair by means of smoothing which smoothed signal is suitable for many purposes such as, for example, switching-off an automatic frequency control or a tuning indication or a tuning correction.

Television receiver having a demodulator circuit for demodulating a

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Eindhoven, Netherlands

Hans J Apeldoorn