VARIABLE RATE PORTAMENTO SYSTEM

摘要

VARIABLE RATE PORTAMENTO SYSTEM A portamento system is disclosed for use with an electronic musical instrument, and particularly with a monotonic keyboard instrument which utilizes master oscillator/ divider elements for tone generation. The portamento system utilizes a voltage controlled oscillator, and an oscillator control circuit comprising a unique combination of a phase/ frequency detector and a circuit for varying and controlling lock up rate and expanding the frequency range of the system which may be either a ramp and hold circuit or a frequency tachometer circuit. The voltage controlled oscillator is thus locked on to the input frequency from the electronic musical instrument with substantially zero phase and frequency error. The system is capable of reaching the input frequency as slowly or as rapidly as desired and will operate over a wide frequency range. A unique system control and interfacing system is also provided whereby the portamento system may be utilized with a plurality of voices of the electronic musical instrument and several modes of operation may be selectively utilized.