A4 FSK Dual Oscillator

FSK Dual Oscillator

This is an A4 rework of my earlier uFSK module.
Frequency shift keying is a method of digital data transmission by frequency modulation of a carrier to represent ones and zeros. Here we are switching between two different oscillators using a third signal. Typically the modulator is some sort of square wave but I extended the concept to allow for any type audio modulation. The modulator crossfades between oscillator A and B over the range -1 to 1. In essence it’s a type of frequency modulation. Depending on the oscillator waveforms, their relative frequency and the waveform and frequency of the modulator you can generate some very harmonically rich outputs. It uses the built-in oscillator node so the fundamental waveforms are de-aliased. The waveform type and shape can be selected. There are two 1 per octave inputs which can be linked using the toggle. The input below the toggle changes the toggle’s state. There are coarse and fine frequency controls, and an output level control for each oscillator. The fsk audio modulator can be either external, or a square wave derived from oscillator A, controlled by the int/ext toggle of modulation input. There is also a sync input for the two oscillators. There is the FSK output and ring modulation of each oscillator with the fsk signal and with each other. The fsk output is low-pass filtered at 10kHz to reduce aliasing.


Input Signal Range Notes
osc A and B 1 per octave two inputs - can be linked
link gate sums the two oscillator inputs when active
sync gate sync input for the two oscillators
int ext gate when high uses the external fsk input
ext 0-1 modulation external fsk modulation (signal is typically at audio frequencies)

Output Signal Range Notes
fsk -1 - 1 audio primary mixed signal output
As -1 - 1 audio A * fsk ring mod
AB -1 - 1 audio A *B * ring mod
Bs -1 - 1 audio B * tsk ring mod


Control Function Notes
link link toggle when active links the 1 per octave inputs together
tune knob coarse frequency control 50% is concert pitch
fine tune knob fine frequency control 50% is concert pitch
wave%20type selects waveform
wave shape knob wave shape control wave shape for square and ramp waves
int ext internal/external fsk toggle selects fsk source



Version History

Revision File Date Notes
2.2 superceded 12/17/2022 Initial upload to Forum
2.3 A4 FSK Dual Oscillator V2.3.audulus4 (19.5 KB) 12/23/2022 minor UI changes


Revision File Date Notes
2.2 superceded 12/17/2022 current demo is pretty lame
2.3 A4 FSK Dual Oscillator Demo V2.3.audulus4 (120.4 KB) 12/23/2022 slightly less lame
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Love these updates, keep 'em coming! :slight_smile:

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Cool. Canvas node tuning fork display!

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