Adaptive Sampling Phase Selection for Serial Signal Jitter
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Solution Overview
Problem
Existing serial communication systems, such as DigRF interfaces, face challenges in maintaining low bit error rates due to phase noise and jitter, especially when the receiver clock is not synchronized with the transmitter clock, leading to errors in data recovery and requiring redundant error correction at higher protocol levels.
Innovation Solution
The implementation of an adaptive phase sequence system that dynamically adjusts sampling phases during signal regeneration, using oversampling and differential error comparisons to determine the optimal sampling phase, thereby reducing bit errors and phase noise impacts, and allowing for continuous data sampling across all phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If oversampling is used to achieve low bit error rate, then data recovery accuracy is improved, but device complexity increases
Solution Approach 1:
The system uses the synchronization sequence itself as the reference for determining optimal sampling phases. The known synchronization pattern enables the receiver to automatically identify which sampling phases yield correct data values, eliminating the need for external calibration or complex training sequences. This self-service approach achieves accurate sampling phase selection while keeping the system relatively simple.
Solution Approach 2:
The system dynamically selects sampling phases based on the detected quality of the data signal. When signal quality deteriorates (e.g., due to phase noise or jitter), the system can switch to alternative sampling phases that are more robust to the current impairments. This parameter change strategy allows adaptive optimization of sampling timing without requiring a fixed, overly complex sampling architecture.
2Ease of operation
If a fixed reference sampling phase is selected from synchronization sequence, then initial data recovery is enabled, but the system cannot adapt to signal degradation during frame transmission
Solution Approach 1:
The system continuously monitors the quality of the data signal during frame transmission by checking whether sampled values match expected patterns. When degradation is detected (e.g., increased bit error rate or mismatch with expected synchronization patterns), the system provides feedback to adjust the sampling phase selection. This feedback mechanism enables adaptive response to signal deterioration while maintaining straightforward initial operation based on the synchronization sequence.
Solution Approach 2:
The sampling phase selection transitions from a static reference determined during synchronization to a dynamic selection that can change during frame transmission. The system can switch between different sampling phases depending on the current signal conditions, making the sampling timing adaptive rather than fixed. This dynamic approach allows the system to respond to phase noise, jitter, and other time-varying impairments.
3Reliability
If redundant error correction codes are used at high protocol levels, then bit errors can be corrected, but transmission efficiency decreases
Solution Approach 1:
The system performs preliminary actions to prevent errors before they occur by optimally selecting sampling phases based on signal quality assessment. By proactively adjusting sampling timing to avoid regions affected by phase noise or jitter, the system reduces the occurrence of bit errors in the first place. This preventive approach decreases the need for subsequent error correction, thereby improving transmission efficiency while maintaining reliability.
Data Source
AI summary
Embodiments of the invention relate to methods and circuits for controlling the sampling phase of a signal that is to be regenerated by sampling, particularly a serial communication signal, having method steps or means for oversampling the signal in order to ascertain samples of the signal during predetermined sampling phases, for determining differential errors between the samples during different instances of the predetermined sampling phases, for determining a differential error rate between the samples to at least one first and at least one second sampling phase on the basis of the ascertained differential errors, and for comparing at least two differential error rates based on at least two different sampling phase pairs in order to ascertain a decision concerning which of the predetermined sampling phases can be selected as a reference sampling phase for correctly regenerating the signal.