uFSK Frequency Shift Keyed Dual Oscillator




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 of 0-1 modulator. The modulator varies the mix between oscillator A and B using a crossfade node. I suppose it’s really a sort 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 modulator can be either external, or a square wave derived from oscillator A, controlled by the int/ext toggle. Again, the input below the toggle can be used to change it’s state. There is also a sync input for the two oscillators. There is the switched output and ring modulation of each oscillator with the fsk signal and with each other. The fsk signal is low-pass filtered at 10kHz to reduce aliasing.


Input Signal Range Notes
o%20input 1 per octave two inputs - can be linked
fsk%20input 0-1 modulation modulation signal is typically at audio frequencies
sync%20input gate oscillator sync input

Output Signal Range Notes
fsk%20output 0-1 audio primary mixed signal output
A%20ring%20mod A * fsk ring mod
B%20ring%20mod B * fsk ring mod
AB%20ring%20mod A * B ring mod


Control Function Notes
link%20switch link toggle on (red) links 1 per octave inputs together - input changes toggle state
frequency%20coarse coarse frequency control 50% is concert pitch
frequency%20fine fine frequency control 50% is concert pitch
wave%20type selects waveform
wave%20shape wave shape control wave shape for square and ramp waves
int-ext%20fsk selects external or internal fsk source on (red) for external fsk source - input changes toggle state



Version History

Revision File Date Notes
2.2 uFSK oscillator V2.2.audulus (39.4 KB) 05/27/2018 initial upload to new forum


Revision File Date Notes
1.0 uFSK Oscillator V2.2 demo.audulus (1.5 MB) 05/27/2018 Runs on iPad Air 2. I had the triggers mapped to my Korg nanoPad.
3.0 uFSK Oscillator V2.2 demo III.audulus (2.8 MB) 05/27/2018 runs at 45% on my Mac
Window transform module (WTF?)
Considering a Fully Portable Modular
New Modules Basic Principles Good Audio

!!! THANKS you just saved me $300


Glad you gave me the idea. I really like the variety of sounds you can get out of this oscillator.


i was buying this today :
i just checked the forum and uFSK dual Osc is something i can build on
EVERYTHING is possible with Audulus !!


except midi out :wink:


i don’t use midi , so for me that is not a issue