Method and apparatus for the modeling and synthesis of harmonic distortion

DETAILED DESCRIPTION Accordingly, several objects and advantages of my invention are to provide a distortion modeling and synthesis method whereby analog audio distortion devices are accurately emulated using digital techniques, to provide a distortion modeling and synthesis method capable of synthesizing a virtually unlimited variety of distortion effects, and to provide a distortion modeling and synthesis method capable of suppressing the aliasing noise that can result when performing a non-linear operation in a digital system.
It is an additional object of the invention to provide a distortion modeling and synthesis method that permits modification of the distortion in terms of the harmonics it produces.
It is an additional object of the invention to provide a distortion modeling and synthesis method that facilitates efficient storage of distortion models for later recall and usage.
To accomplish the above-mentioned objects, the harmonic distortion effect of an audio distortion device is modeled by determining the harmonic characteristics of the distortion imparted to a signal by the distortion device.
A distortion synthesizer uses the resulting distortion model to synthesize the distortion characteristics of the distortion device.
The synthesized harmonic distortion effect imparted to a signal is virtually identical to that of the distortion device used to create the model.
To create a distortion model, the distortion device is operated using a pure, undistorted sinusoidal signal as an input.
Spectral analysis is performed on the output signal from the distortion device to determine the amplitude and phase of the signal's harmonic components.
The harmonic amplitude and phase parameters form the distortion model.
A process is provided for correcting the phase parameters of distortion models created from distortion devices that induce phase shifts into the distorted signal.
The distortion synthesizer provides a mechanism that uses the distortion model in performing a non-linear transformation of a digital signal