Waveform Sample Selection for Accurate DUT Measurement
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Solution Overview
Problem
Existing test and measurement instruments provide non-equivalent measurement results for device under test (DUT) due to methods that do not accurately characterize the DUT's real-world behavior, particularly for non-linear devices, leading to issues like error vector magnitude (EVM) and non-ideal digital pre-distortion (DPD) measurements.
Innovation Solution
A test and measurement instrument that selects a subset of samples from a waveform based on predefined criteria concerning bandwidth, amplitude distribution, and amplitude percentiles, generating a modified waveform for measurement, thereby reducing the number of samples required and ensuring accurate characterization of the DUT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a real-world signal with full bandwidth and amplitude distribution is used for measurement, then measurement accuracy and reliability are improved, but measurement time increases significantly
Solution Approach 1:
The patent segments the original waveform into multiple segments and selects only representative segments for measurement. This segmentation approach maintains the essential characteristics (bandwidth, amplitude distribution, amplitude percentiles) while reducing the total number of samples processed, thereby decreasing measurement time while preserving measurement accuracy.
Solution Approach 2:
The patent extracts and retains only the critical portions of the waveform that contain essential measurement information. By identifying and keeping segments that represent the full amplitude distribution and bandwidth characteristics, the method removes redundant data, achieving faster measurements without sacrificing accuracy.
2Reliability
If the full waveform with all samples is analyzed, then complete characterization of the device under test is achieved, but computational effort and measurement time increase
Solution Approach 1:
The patent applies partial action by analyzing only a selected subset of waveform segments rather than the complete waveform. The selection criteria ensure that the chosen segments contain sufficient information for reliable device characterization, achieving adequate measurement results with reduced computational effort and improved efficiency.
Solution Approach 2:
The patent changes the measurement approach by focusing on specific parameters (bandwidth, amplitude distribution, amplitude percentiles) rather than analyzing all samples uniformly. This parameter-based selection enables efficient identification of representative segments, maintaining characterization reliability while improving measurement efficiency.
3Productivity
If a reduced signal is used to decrease measurement time, then measurement speed improves, but measurement results become non-ideal and less accurate
Solution Approach 1:
The patent applies local quality by ensuring that the selected waveform segments locally represent the global characteristics of the full signal. Each selected segment is evaluated based on its ability to capture essential features (amplitude distribution, bandwidth, percentiles), ensuring that the reduced set of segments maintains overall measurement accuracy while improving speed.
Data Source
AI summary
A test and measurement instrument includes an input configured to receive at least a waveform of a test signal, which includes a plurality of samples. The test and measurement instrument includes a processing circuit connected with the input. The processing circuit is configured to analyze the waveform and to select at least a subset of samples out of the plurality of samples. The subset of samples matches predefined criteria concerning at least one of bandwidth, amplitude distribution, and amplitude percentiles. The test and measurement instrument is configured to generate a modified waveform based on the selected subset of samples and/or to measure only a part of a received measurement signal from a device under test, which corresponds to the selected subset of samples. Further, a test and measurement setup and a method of measuring a device under test are described.