Test Instrument Waveform Segmentation for Inter-System Interference
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Solution Overview
Problem
Current oscilloscope acquisition systems face convolution issues when processing waveforms from devices under test (DUT) with varying S-parameters, leading to erroneous measurements due to inter-system interference, particularly in time-variant systems like MIPI and DDR buses with different impedance characteristics.
Innovation Solution
A test and measurement instrument with a receiver, digitizer, and processor that identifies and separates waveforms based on different S-parameter characteristics, using a system separation unit to prevent inter-system interference by applying DSP and SDLA filters to each separated waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If filters are applied to process the entire waveform, then measurement smoothing is improved, but measurement precision deteriorates due to convolution of data from different system characteristics
Solution Approach 1:
The waveform is divided into multiple segments based on temporal descriptor information that identifies different system characteristics (e.g., different DUT states, impedance changes, transmitter switches). Each segment is processed independently with appropriate filters, preventing convolution of data from different system characteristics while maintaining measurement precision and reliability.
2Measurement precision
If de-embedding or simulation filters are applied, then signal analysis accuracy is improved, but measurement reliability deteriorates due to inter-system interference from varying S-parameters
Solution Approach 1:
The waveform is segmented according to temporal descriptors that indicate changes in S-parameters or system characteristics. De-embedding or simulation filters are applied only to relevant segments with matching characteristics, eliminating inter-system interference while preserving signal analysis accuracy and measurement reliability.
Solution Approach 2:
Different filtering approaches (including de-embedding and simulation filters) are applied locally to specific waveform segments based on their unique characteristics identified by temporal descriptors. This ensures each segment receives the most appropriate processing while avoiding contamination from segments with different system characteristics.
3Device complexity
If a single filter is used for the entire data record, then processing simplicity is maintained, but measurement precision deteriorates due to convolution of data from different DUT characteristics
Solution Approach 1:
The data record is segmented based on temporal descriptor information that identifies transitions in DUT characteristics. Each segment is processed with appropriate filters, improving jitter measurement precision while maintaining processing efficiency through automated segment identification and independent processing.
Data Source
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AI summary
A method of preventing inter-system interference while acquiring waveforms in a test and measurement instrument with variation in a device under test system S-parameters. The method includes receiving a waveform from a device under test at the test and measurement instrument, digitizing the waveform, identifying portions of the digitized waveform with different S-parameter characteristics, separating the identified portions of the digitized waveform into different waveforms, and displaying the different waveforms to a user.