METHOD AND APPARATUS FOR DATA ACQUISITION WITH WAVEFORM TRIGGER

摘要

Digital signal acquisition system is triggered when an input waveform matches a known reference waveform. This is achieved by calculating a stream of error metric values defined as a sum of absolute values of differences between incoming and reference samples. An error metric is calculated using only byte operations, which is advantageous for hardware implementation. A waveform trigger is determined by a sample index corresponding to a minimum value of the error metric and corresponds to a best match between input and reference waveforms. A waveform trigger is used for synchronous averaging and estimating time domain noise voltage. A reference waveform updates in poor SNR conditions to provide robust estimates of time domain noise by reducing reference waveform jitter.

主权项

1. A method of data acquisition with waveform triggering, comprising the steps of:
A. defining a reference waveform pattern for waveform triggering, and digitizing the reference waveform pattern to generate for a succession of reference sample times, a corresponding sequence of digitized reference pattern samples; B. digitizing an input waveform to generate for a succession of input sample times corresponding to the respective reference sample times, a sequence of digitized input waveform samples, and calculating a stream of error metric values based on a detected deviations of the input pattern samples from respective reference waveform samples; C. comparing respective error metric values with a predetermined trigger threshold and determining a sample index, wherein the sample index is representative of a minimum error metric value below the trigger threshold; and D. using the determined sample index as a waveform trigger index for triggering sampling of input waveforms.