Method and apparatus to evaluate audio equipment via filter banks for dynamic distortions and or differential phase and frequency modulation effects

摘要

A testing method or apparatus utilizes filter banks to measure time varying or dynamic harmonic distortion or intermodulation distortion from a device. With a stairstep or arbitrary signal and filter banks, Nth order harmonic and or intermodulation distortion is measured via the filter banks at different offsets provided by an arbitrary low frequency signal. An amplifier with crossover distortion will show increased harmonic and or intermodulation distortion near the zero crossing while providing less distortion in other portions of the transfer curve of the amplifier. One or more distortion signals from the device (e.g., audio device) may be measured for a phase and or frequency modulation effect.

主权项

1. Method of measuring a time varying or dynamic intermodulation distortion from an audio device, wherein the audio device has an input and an output, comprising:
providing a first signal comprising an arbitrary waveform, a second signal whose frequency is higher than the frequency of the first signal, and a third signal whose frequency is higher than the frequency of the second signal to an input of the audio device; coupling the output of the audio device to an input of one or more bandpass filters, wherein the one or more bandpass filter provides a filter bank, and wherein the one or more bandpass filters includes at least one output terminal; measuring the time varying intermodulation distortion via measuring or displaying an amplitude level from one or more output terminals of the bandpass filters to provide a time varying intermodulation distortion measurement of the audio device, wherein the time varying intermodulation distortion measurement includes measuring an intermodulation distortion signal related to the second and third signals, and wherein the time varying intermodulation distortion signal is varied or induced in time by the first signal.