AudioQAM

AudioQAM simultaneously modulates phase and amplitude of audio input, and as a result, creates unexpected sound.

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Quadrature Amplitude Modulation (QAM) is widely used in digital communications. AudioQAM is derived from digital quadrature amplitude modulators and refined for audio processing. AudioQAM supports sine as well as triangle, square, and sawtooth waveforms for carrier waves.

In the case of the sine waveform carrier, AudioQAM is essentially equivalent to the phase shift network and thus works as the well-known Bode frequency shifter. However, the low-frequency shift of conventional frequency shifters results in the spectral inversion band. Since it typically creates noisy sounds, AudioQAM supports automatic input band-limiting that suppresses the spectral inversion band.

In the triangle, square, and sawtooth waveform carrier cases, the output spectrum is the convolution of the carrier wave and audio input spectrums, therefore creating unknown sound. AudioQAM automatic input band-limiting also optimizes superimposed spectrum by the convolution, thus it could create clearer sound.

AudioQAM is provided as a VST 3 plug-in for digital audio workstations and supports any sampling rates. OS environment is 64-bit Windows 10 and later.