Bit Stream Pattern Overlay for Serial ATA Signal Integrity
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Solution Overview
Problem
Current methods for testing signal integrity of high-speed serial digital signals, such as Serial ATA-II, face limitations including false triggering, limited oscilloscope bandwidth, and insufficient data matrix resolution, which hinder accurate pattern identification and bit-level measurements, especially for signals with repetitive patterns arriving at sporadic intervals.
Innovation Solution
Converting the acquired waveform signal into a bit stream, comparing it to a pre-defined pattern string to identify corresponding patterns, overlaying these patterns in a hit matrix, and generating histograms for each bit to perform precise voltage level measurements, thereby eliminating false triggering and enhancing resolution beyond the limitations of traditional wfmDB mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pattern trigger decoding is used to accumulate samples in wfmDB mode, then samples can be accumulated for waveform analysis, but false triggering occurs and incorrect eye patterns are generated
Solution Approach 1:
A de-jitter buffer is introduced as an intermediary component between the trigger system and the wfmDB accumulation process. This buffer absorbs timing variations and jitter in the trigger events, ensuring that samples are accumulated at consistent time intervals relative to the actual signal pattern, thereby preventing false triggering while maintaining sample accumulation capability
Solution Approach 2:
The system performs preliminary pattern recognition and timestamp identification on the bit stream before initiating the wfmDB accumulation process. By pre-identifying valid pattern occurrences and their precise timestamps, the system ensures that only correctly triggered events are accumulated, eliminating false triggers at the source
2Quantity of substance
If traditional wfmDB mode is used for signal analysis, then waveform accumulation is possible, but the data matrix resolution is insufficient for high-speed signals
Solution Approach 1:
The system changes the fundamental parameter of how data is organized and stored by transitioning from a fixed 2D matrix structure to a 1D timestamped bit stream structure. This allows for much finer temporal resolution because samples are recorded at their actual occurrence times rather than being forced into fixed matrix bins, achieving sub-4ps resolution for high-speed signals
Solution Approach 2:
The invention adds a time dimension to the data structure by recording precise timestamps for each bit in the bit stream. This transforms the analysis from a 2D matrix (amplitude vs. normalized time) to a 3D representation (amplitude vs. absolute time timestamp), enabling much higher effective resolution along the time axis
3Speed
If oscilloscope bandwidth is limited to 1.25 Gbps, then the device remains cost-effective, but it cannot measure high-bandwidth signals like Serial ATA at 3 Gbps
Solution Approach 1:
The system replaces the need for high-bandwidth analog oscilloscope hardware with a different measurement approach: using a lower-bandwidth oscilloscope in conjunction with a separate high-speed pattern recognition and timestamping system. The high-speed pattern detection occurs in the digital domain rather than requiring high analog bandwidth, substituting mechanical/electrical limitations with algorithmic processing
Data Source
AI summary
A method of pattern identification and bit level measurements for a high speed digital signal using an oscilloscope converts an input waveform into a bit stream sequence. From the bit stream sequence pre-defined patterns are identified and overlaid on each other to form a superimposed pattern. A center region for each bit of the superimposed pattern is identified, and appropriate voltage measurements within the respective center regions are taken for the bit levels.