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In order to obtain a stereophonic coder, the levels of the signals S.sub.1, S.sub.2 relative to the two channels of a stereophonic system are modified and combined so as to generate a waveform in which the harmonics up to the 6th included have been suppressed; this is achieved by switching actions which occur at intervals of 1/8 f (f being the frequency of the subcarrier) and are such that a signal is obtained which in the successive intervals is proportional to: ##EQU1## then to the above values repeated in reverse order, then again to the values repeated in the direct order, and so on. The invention concerns also the coder performing such a process.

Inventor: Gianfranco Lorea
Current U.S. Classification: 381/7; 332/151
International Classification: H04H 500

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Citations

Cited PatentFiling dateIssue dateOriginal AssigneeTitle
US3711652Mar 10, 19711973MONOLITHIC STEREO DECODER WITH BALANCED DECODER OPERATION
US3789323May 19, 1972Jan 29, 1974FREQUENCY KHZ CO

Referenced by

Citing PatentFiling dateIssue dateOriginal AssigneeTitle
US4404430Nov 20, 1981Sep 13, 1983Nippon Gakki Seizo Kabushiki KaishaFM Stereo demodulation circuit with voltage dividing and multiplexing techniques
US4433433May 15, 1981Feb 21, 1984Trio Kabushiki KaishaSampling pulse forming circuit for FM stereo demodulator
US5648629Jun 27, 1994Jul 15, 1997Yamaha CorporationElectronic musical instrument with resonance sounds
US7519348Mar 11, 2005Apr 14, 2009RF Magic, Inc.Harmonic suppression mixer and tuner

Claims

1. A process for realizing a stereophonic coder, characterized in that it consists in employing signals S.sub.1 and S.sub.2, already pre-emphasized, relative to the left and respectively the right channel of a stereophonic system, by modifying and combining their levels in successive time intervals so as to obtain a waveform without the harmonics up to the 6th one included; this result being obtained by switching actions occurring at time intervals equal to 1/8f, f being the frequency of the subcarrier, in such a way that in the successive intervals a signal S.sub.u is generated proportional to the following values: ##EQU4## which are then repeated in reverse order, then again in the same order and so on.

2. A process according to claim 1, characterized in that said frequency f is 38 kHz.

3. A process according to claims 1 or 2, characterized in that the pilot signal of the stereophonic coder is obtained by employing switching actions which follow one another at time intervals of 1/152000 sec so as to give sequential levels proportional to the following values: ##EQU5## these values being then repeated in reverse order, in direct order, in reverse order and so on.

4. A stereophonic coder characterized in that it comprises more than two switches synchronously driven and associated to voltage or current dividers so as to obtain the suppression of the harmonics up to the 6th one by applying the process according to claim 3.

5. A stereophonic coder according to claim 4, characterized in that it comprises switching and dividing means arranged to generate the pilot signal through a multilevel switching, eliminating the harmonics of said signal up to the 6th one included.

6. A stereophonic coder according to claim 5, characterized in that the switching actions which serve to generate the pilot signal follow one another at a rate of 1/152000 sec.

Drawings