Phase Jump Saturation Avoidance in Distributed Acoustic Sensing
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Solution Overview
Problem
Distributed acoustic sensing (DAS) systems using coherent Rayleigh backscattering face issues with phase jump saturation, leading to overflow and spikes in high-pass filter outputs due to limited processing resources and noise, which disrupt signal detection and vibration analysis.
Innovation Solution
The method adjusts the phase by adding or subtracting N·2π to bring the phase within a supported range, outputs the adjusted phase with a flag signal, and buffers previous samples in the high-pass filter to eliminate spikes, ensuring continuous signal detection without saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase unwrapping is performed in DAS systems, then signal detection capability is improved, but phase saturation and overflow occur causing spikes in filter output
Solution Approach 1:
The patent applies preliminary action by detecting phase saturation conditions before they cause harmful effects. The system monitors the unwrapped phase signal and identifies when it approaches saturation limits, then proactively applies corrections by adding or subtracting 2π to bring the phase back within the valid range, preventing overflow and subsequent spikes in the high-pass filter output.
Solution Approach 2:
The patent converts the harmful effect of phase saturation into a beneficial correction mechanism. When phase saturation is detected, the system intentionally introduces a controlled phase adjustment (adding or subtracting 2π) that eliminates the saturation artifact. This transforms the potential harmful overflow into a corrective action that maintains signal integrity and prevents spike generation in the filter output.
2Measurement precision
If high-pass filtering is applied to remove DC components, then vibration detection is improved, but phase saturation causes spikes and ripples in filter output
Solution Approach 1:
The patent applies preliminary action by correcting phase saturation in the unwrapped phase signal before it enters the high-pass filtering stage. By detecting and correcting saturation conditions ahead of time through 2π adjustments, the system prevents saturated values from being processed by the filter, thereby eliminating the source of spikes and ripples that would otherwise be generated in the filter output.
Solution Approach 2:
The patent converts the harmful saturation artifacts into a beneficial correction opportunity. When saturation is detected, the intentional 2π phase adjustment transforms what would be a harmful overflow condition into a controlled correction that eliminates the saturation artifact. This ensures the high-pass filter receives clean, unsaturated input signals, preventing spike and ripple generation while maintaining vibration detection capability.
3Productivity
If phase values are kept within limited processing range, then computational resources are conserved, but phase jump saturation occurs disrupting signal continuity
Solution Approach 1:
The patent applies preliminary action by monitoring phase values as they approach the limited processing range boundaries and correcting them before saturation occurs. The system detects when the unwrapped phase nears saturation limits and proactively applies 2π adjustments to keep the phase within the valid range, preventing signal discontinuity while maintaining computational efficiency through constrained phase values.
Solution Approach 2:
The patent implements feedback by continuously monitoring the unwrapped phase signal for saturation conditions and applying corrective 2π adjustments when saturation is detected. This closed-loop feedback mechanism ensures phase values remain within the limited processing range while maintaining signal continuity, as the feedback correction prevents the phase from exiting the valid range and causing discontinuities that would disrupt signal processing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively prevents phase jump saturation, removing spikes and ripples from high-pass filter outputs, enabling reliable real-time monitoring and improved signal integrity in DAS systems.
Implementation Method 1
Distributed acoustic sensing (DAS) using coherent Rayleigh backscattering in an optical fiber
Data Source
AI summary
Aspects of the present disclosure describe systems methods and structures for avoiding saturation caused phase jump in systems that extract information from the phase of a complex sequence and exhibit an overflow or “spike” in the output of a high-pass filter. Operationally, during phase unwrapping—when an output signal exceeds a supported range—it is adjusted to be back in range by adding N·2π, to a phase where N is negative or positive integer, depending on the direction to be adjusted.