Amplitude Modulation Generator

miniMO's Amplitude Modulation Generator produces a variety of tones resulting from three flavors of Amplitude Modulation, using two waves stored internally (more details here).

SOURCE CODE

Download from Github

FEATURES

  • Waveforms: sine, triangle, square, saw
  • Modulation types: Ring Modulation, Amplitude Modulation, Amplitude Modulation Plus
  • Real time wave switching
  • Real time modulation type switching
  • Frequency Range: 0-3.8 KHz (both for carrier and modulator)
  • Real time frequency control (both for carrier and modulator)
  • Real time frequency modulation (independent for carrier and modulator)
  • Automatic Battery check

MANUAL

I/O

  • 1&2: Outputs - processed signal
  • 3: Input - modulates currently selected parameter
  • 4: Input - always modulates the frequency of the modulator wave

OPERATION

  • Knob: change carrier frequency (default) or modulator frequency
    • When you change between parameters, miniMO memorizes the point where you leave the knob
    • When you start modifying a parameter again, miniMO waits until you reach the value where you left it earlier
  • Click: toggle between carrier or modulator freq
    • The LED blinks once
  • Double Click: cycle through the available wave shapes
    • The LED blinks twice
    • Shapes (in order): sine, triangle, square, and saw
    • Note: Both modulator and carrier have the same wave shape
  • Click, hold, and release after a couple of seconds: cycle through the available modulation types
    • The LED blinks thrice
    • Modulation types (in order): Ring Modulation, Amplitude Modulation, and Amplitude Modulation Plus

BATTERY CHECK

When you switch the module ON,

  • If the LED blinks once, the battery is OK
  • If the LED blinks fast several times, the battery is running low

NOTES

ON THE TYPES OF MODULATION

When both the Carrier and Modulator are sine Waves of frequencies F1 and F2 respectively,

  • Ring Modulation produces two new frequencies, F2 + F1, and F2 - F1
  • Amplitude Modulation preserves F2 and also produces F2 + F1 and F2 - F1
  • Amplitude Modulation Plus preserves both F1 and F2, and it also produces F2 + F1 and F2 - F1

ON EXTERNAL MODULATION

If you are controlling the frequency of the modulator wave with the knob,

  • A signal applied to I/O 3 will change the frequency, with the knob setting the central value (offset to both the maximum and minimum values)
  • A signal applied to I/O 4 will change the frequency, with the knob setting the maximum value

ACKNOWLEDGMENTS

This program is based on the Arduino Audio Ring Modulator by Martin Nawrath, as described here.