Oscilloscope Waveform Noise Separation While Preserving SUT Noise

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Solution Overview

Problem

Existing methods for removing intrinsic noise from oscilloscope waveforms either fail to distinguish between signal under test (SUT) noise and instrument noise, or require complex instrument setups, leading to incomplete noise removal or increased complexity.

Innovation Solution

A method involving oversampling and applying a high-pass filter to isolate and quantify intrinsic noise, followed by a low-pass filter to remove it, using a correction factor calculated from the standard deviations of digitizer and combined noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If averaging is used to remove noise, then intrinsic noise is reduced, but SUT noise is also removed along with it

Engineering Contradiction:

Improveintrinsic noiseVSAvoidSUT noise

Core Design Contradiction:

Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The patent segments the total noise into two distinct components: intrinsic noise (from the measurement system) and SUT noise (from the signal under test). This is achieved by capturing multiple waveforms and calculating their standard deviations separately, then using these segmented noise components to apply different correction factors to different parts of the waveform data.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the parameter of noise characterization by using standard deviation calculations on multiple captured waveforms to distinguish between intrinsic and SUT noise. By analyzing the statistical properties of the noise components, the system applies parameter-based differentiation to selectively remove only the intrinsic noise while preserving SUT noise characteristics.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If multiple samplers are used to correct visual display and parametric measurements, then noise removal is improved, but device complexity increases

Engineering Contradiction:

Improveintrinsic noiseVSAvoidinstrument complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent creates a statistical copy or model of the intrinsic noise characteristics by capturing multiple waveforms and calculating their standard deviations. Instead of using multiple physical samplers, the system creates a digital representation of the noise profile that can be applied to correct the waveform, thereby avoiding the need for complex multi-sampler hardware while achieving the same noise removal effect.

Inventive Principle:

Principle #26Copying

3Object-affected harmful factors

If low-pass filter is applied to remove noise, then intrinsic noise is reduced, but all noise including SUT noise is removed

Engineering Contradiction:

Improveintrinsic noiseVSAvoidSUT noise

Core Design Contradiction:

Object-affected harmful factorsVSLoss of information

Solution Approach 1:

The patent applies local quality by treating different noise components differently rather than applying a uniform filtering approach. By calculating separate standard deviations for intrinsic and SUT noise, the system applies localized correction factors to specific portions of the waveform data, ensuring that only the harmful intrinsic noise is removed while the informative SUT noise is preserved.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Effectively separates and reduces intrinsic noise from the waveform representation, preserving SUT noise while maintaining simplicity in instrument setup.

Implementation Method 1

obtaining a time-domain representation of a combined noise of the equivalent-time waveform above the deterministic maximum frequency by applying the equivalent-time waveform to a high-pass filter having a cutoff frequency greater than the deterministic maximum frequency

Methodology Applied

Scientific EffectFilter (electronic): Filter (electronic)

Implementation Method 2

applying the equivalent-time waveform representation to a low-pass filter having the cutoff frequency to obtain an output waveform representation in which the intrinsic noise has been removed

Methodology Applied

Scientific EffectFilter (electronic): Filter (electronic)

Data Source

PatentUS12535515B2Methods of removing intrinsic noise from signal under test (SUT)

Publication Date: 2026.01.27 KEYSIGHT TECHNOLOGIES INC

AI summary

A test system implemented method removes intrinsic noise from a waveform representation of a repeating signal under test (SUT). The method includes obtaining an oversampled equivalent-time waveform representation of the repeating SUT. The method further includes obtaining a time-domain representation of a combined noise of the equivalent-time waveform above the deterministic maximum frequency by applying the equivalent-time waveform to a high-pass filter. The method further includes determining a standard deviation of the time-domain representation of the combined noise, and determining a correction factor α in accordance with the standard deviation of the digitizer noise, and the standard deviation of the time-domain representation of the combined noise. The method further includes applying the equivalent-time waveform representation to a low-pass filter having a unity magnitude response at frequencies below the cutoff frequency and a correction factor magnitude response at frequencies above the cutoff frequency.