Frequency modulator for electronic musical instrument - has combining network for note signals with multipliers and waveform model former

摘要

The signal processing network is for frequency modulating an audio signal to reproduce an effect equivalent to a composition of a number of equal musical sounds. It contains a digital delay line for the audio signal and a timing input whose frequency is determined by the delay. There is also a voltage controlled oscillator, one oscillator for a very low frequency sinusoidal signal and a second oscillator for a one decade higher sinusoidal signal. They are combined to form the control signal. The combining networks are formed by signal multipliers with an added wave shape modelling network, with an exponential transfer characteristic. The frequency of the voltage dependent oscillator is formed by two cascaded units.