# US 5,352,976 A · Multi-channel trigger dejitter

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- Number: US 5,352,976 A
- Document ID: US5352976A
- Status: Granted
- Kind: A
- Application number: 07/828,827
- Filed: 1992-01-31
- Granted: 1994-10-04
- Earliest claimed: 1992-01-31
- Assignees: Tektronix, Inc.
- Inventors: George S. Walker; Eric P. Etheridge
- Web page: https://patentgrep.com/patent/US5352976A

## CPC

- G01R 13/32: Circuits for displaying non-recurrent functions such as transients; Circuits for triggering; Circuits for synchronisation; Circuits for time-base expansion
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

A multi-channel trigger dejitter technique uses actual digitized samples from a repetitive waveform signal to correct for jitter in a hardware trigger signal. Interpolated samples are calculated between a set of the digitized samples about the hardware trigger signal, and a hardware trigger level is determined from the closest sample in time to the hardware trigger signal. The hardware trigger level is averaged with that determined from prior acquisitions to produce an average trigger level. The closest sample in time to the average trigger level becomes an averaged trigger signal, and the times for all the digitized samples for that acquisition, as well as all simultaneous acquisitions from other input channels, are adjusted according the difference in time between the hardware and averaged trigger signals. Over several acquisition iterations of the repetitive waveform the amount of jitter between acquisitions is decreased.

## Claims

### Claim 1

A trigger dejitter method comprising the steps of:
acquiring a set of digitized samples from a repetitive waveform signal about a hardware trigger signal, each digitized sample having a magnitude value and a time relative to the hardware trigger signal;
calculating a set of interpolated samples between the digitized samples;
determining one of the digitized and interpolated samples as a hardware trigger point corresponding to the hardware trigger signal;
averaging the magnitude of the one sample with an average magnitude for trigger points from prior acquisitions;
determining another of the samples as an averaged trigger point corresponding to the average magnitude; and
adjusting the time of each digitized sample according to the difference in time between the hardware and averaged trigger points.

### Claim 2 (depends on 1)

The trigger dejitter method of claim 1 further comprising reiterating the recited steps for a plurality of iterations of the waveform signal.

### Claim 3 (depends on 1)

The trigger dejitter method of claim 1 further comprising the step of displaying the adjusted digitized samples to reproduce the waveform signal.