Single side-band harmonic extension in a polyphonic tone synthesizer

摘要

A keyboard operated musical instrument is disclosed in which a musical tone having an extended range of harmonics is produced by combining two waveshapes at different fundamental frequencies. The first waveshape has a fundamental frequency corresponding to an actuated keyboard switch and has a spectrum containing a maximum of Q harmonics. The second waveshape is created by a single side-band modulation of two orthogonal musical signals each having a maximum of Q harmonics and has a phase coherence with the first waveshape. The second waveshape is generated at a frequency which is Q+1 greater than the fundamental frequency of the first waveshape. The first and second waveshapes are combined to produce a musical tone which has an extended range of harmonics.