Waveform timing alignment system for digital oscilloscopes

Abstract

A method and an apparatus detect the presence of and correct for timing misalignment between waveforms acquired by digital oscilloscopes. In a preferred embodiment, a digital oscilloscope (50) includes a waveform alignment system (60) that receives a first waveform (86) and a similar second waveform (88) of a periodic electrical signal. A digital signal processor (80) of the waveform alignment system generates an autocorrelation value in connection with the first waveform and a first cross-correlation value in connection with the first and second waveforms and compares the values to determine whether they differ by more than a preselected tolerance, thereby to detect a timing misalignment between the first and second waveforms. Upon detection of a timing misalignment, the digital signal processor computes a shifted second waveform by changing the timing relationship of the second waveform relative to the first waveform and generates a second cross-correlation value in connection with the first waveform and the shifted second waveform. The digital signal processor shifts the second waveform relative to the first waveform such that the second cross-correlation value differs from the autocorrelation by less than the preselected tolerance, thereby to correct the timing misalignment.

Dependencies are inferred from the claim text.