Waveform Search by Example for Oscilloscope Defect Detection

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Solution Overview

Problem

Conventional test and measurement instruments, such as oscilloscopes, face challenges in accurately and efficiently locating recurring defects or patterns in input signals, particularly due to irregular appearances of cross-talk and other signal anomalies, which can degrade performance and are difficult to detect using existing techniques.

Innovation Solution

The implementation of a 'search by example' feature in test and measurement instruments, allowing users to select a portion of a waveform and search for similar instances within the stored sample waveform, using correlation algorithms like InterClass Correlation (ICC) to identify matches visually on the display, with adjustable threshold controls for matching criteria.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional trigger and searching techniques are used to locate defects or patterns, then the instrument can identify some recurring signals, but the detection accuracy deteriorates when signals vary irregularly or have qualities that escape detection

Engineering Contradiction:

Improvedefect detection accuracyVSAvoidability to detect varying signal patterns

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent uses template matching where a user-defined waveform segment serves as a template (copy) to search for similar patterns throughout the acquired waveform. This allows the instrument to locate recurring defects or patterns by comparing each segment against the template, significantly improving detection accuracy for varying signal patterns that conventional triggers cannot identify

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent implements adjustable matching criteria parameters including correlation threshold, time shift tolerance, and amplitude scaling factors. These parameters can be modified to adapt to different signal characteristics and defect types, enabling the system to maintain high detection accuracy across diverse and varying signal patterns

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the instrument stores the entire acquired waveform for analysis, then all signal portions are available for searching, but the memory requirements and processing time increase

Engineering Contradiction:

Improvecompleteness of waveform analysisVSAvoidsearch processing time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent divides the acquired waveform into multiple segments and performs template matching independently on each segment. This segmentation approach allows parallel processing of different waveform portions, reducing overall search time while maintaining complete coverage of the entire waveform for reliable defect detection

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent pre-processes the acquired waveform into segments and pre-calculates correlation values or other matching metrics before the actual search is initiated. This preliminary preparation reduces the computational burden during the search phase, enabling faster processing while ensuring all waveform data is available for analysis

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If the user manually analyzes the waveform to locate defects, then detailed inspection is possible, but the time required and complexity of operation increase significantly

Engineering Contradiction:

Improvedefect location accuracyVSAvoiduser operation simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent implements automatic template matching that performs the defect search and identification without requiring manual waveform inspection. The system automatically compares waveform segments against the template, identifies matches exceeding the correlation threshold, and presents results to the user, thereby maintaining high defect location accuracy while dramatically simplifying operation

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20230333148A1Device and method for waveform searching by example

Publication Date: 2023.10.19 TEKTRONIX INC

AI summary

A test and measurement instrument includes an input for accepting an input signal from a Device Under Test (DUT), acquisition memory for storing a sampled waveform derived from the input signal, an output display, and one or more processors configured to accept a portion of the sampled waveform as a search portion, search the sampled waveform for portions similar to the search portion, and visually indicate, on the output display, portions of the sampled waveform that are similar to the search portion as matched portions. Methods of operation and description of storage media, the operation of which performs the above operations, are also described.