Equivalent-Time Sampling Trigger Holdoff Optimization
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Solution Overview
Problem
Traditional equivalent-time sampling oscilloscopes face reduced sampling rates due to long pattern lengths and slow pre-scaled clocks, leading to increased test time and reduced waveform throughput, especially when dealing with high symbol rates like 26 GHz PRBS16 signals.
Innovation Solution
The implementation of an optimized pattern acquisition method that sets a trigger holdoff value equal to the smallest integer multiple of the time between samples, allowing for maximum sampling rate retention in pattern-synchronous mode, and the introduction of optimized single strobe partial pattern acquisition to reduce measurement times by increasing acquisition update rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional equivalent-time sampling oscilloscopes use pattern-synchronous clock-triggered mode with slow pre-scaled clocks, then coherent time-domain waveform reconstruction is achieved, but the equivalent-time sampling rate is reduced
Solution Approach 1:
The system dynamically adjusts the trigger holdoff period based on the relationship between pattern length and symbol rate. When the pattern length is less than the symbol rate divided by the minimum trigger holdoff, the system uses an optimized holdoff period to maximize sampling rate. When the pattern length exceeds this threshold, the system switches to traditional pattern-synchronous mode to maintain waveform coherence, thus adapting the sampling strategy to current test conditions.
Solution Approach 2:
The invention changes the trigger holdoff parameter from a fixed pattern-synchronous value to an optimized value calculated as the maximum of the minimum trigger holdoff and the pattern length divided by an integer factor. This parameter change allows the system to operate at maximum sampling rate for short patterns while maintaining coherent reconstruction for long patterns.
2Reliability
If long pattern lengths are used in pattern-synchronous mode, then complete pattern acquisition is achieved, but the equivalent-time sampling rate is reduced
Solution Approach 1:
For short patterns where complete pattern acquisition at maximum sampling rate is sufficient, the system uses partial pattern acquisition with optimized trigger holdoff, acquiring only the necessary samples at maximum rate. For long patterns, the system uses full pattern-synchronous acquisition to ensure complete pattern capture, accepting the reduced sampling rate as necessary for reliability.
Solution Approach 2:
The acquisition process is segmented into two distinct modes: optimized mode for short patterns and pattern-synchronous mode for long patterns. The system segments the decision space based on the relationship between pattern length and symbol rate, applying different acquisition strategies to different segments to optimize both throughput and completeness.
3Stability of the object's composition
If the trigger clock is divided down to match the pattern symbol rate, then pattern synchronization is maintained, but the sampling rate is reduced due to minimum trigger holdoff constraints
Solution Approach 1:
The system performs preliminary calculation of the optimized trigger holdoff period before acquisition based on the known pattern length and symbol rate. This preliminary action allows the system to set the optimal holdoff value in advance, avoiding the need for conservative divided-down clock rates and enabling maximum sampling rate operation from the start of acquisition.
Data Source
AI summary
An equivalent-time sampling test and measurement instrument for acquiring a repeating pattern signal under test at or near a maximum sampling speed of the test and measurement instrument. The test and measurement instrument includes a first input configured to receive repeating pattern information about a signal under test, a second input configured to receive the signal under test, one or more processors configured to determine an optimized trigger holdoff period that is set based on a minimum trigger holdoff period of a test and measurement instrument, and an acquisition unit configured to acquire a portion of the signal under test every optimized trigger holdoff period.