I/Q Data Balancing via Ellipse Fitting for Distributed Acoustic Sensing
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Solution Overview
Problem
Fiber optic sensing systems, particularly distributed acoustic sensing (DAS) systems, face challenges in accurately extracting phase information due to I/Q imbalance issues caused by imperfections in optical components, such as DC offset and amplitude/phase mismatches, which affect the accuracy of digital signal processing and subsequent parameter recovery.
Innovation Solution
The implementation of an I/Q data balancing scheme using ellipse fitting to correct imperfections in I/Q data, improving the signal-to-noise ratio (SNR) and enabling more confident extraction of phase information with enhanced temporal consistency, applicable to DAS systems and other photonic sensing solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If straightforward extraction of phase information from I/Q data is performed, then the process is simple, but the accuracy of phase information is degraded due to I/Q imbalance
Solution Approach 1:
The patent applies preliminary action by performing ellipse fitting and I/Q data balancing before phase extraction. The system pre-calculates correction parameters based on the elliptical trajectory of I/Q data points and applies these corrections in advance, enabling accurate phase extraction while maintaining operational simplicity.
2Measurement precision
If I/Q data balancing with ellipse fitting is applied, then the accuracy of phase information is improved, but the computational complexity increases
Solution Approach 1:
The patent transforms the complex I/Q imbalance correction problem into a parameter estimation problem by fitting an ellipse to the I/Q data trajectory. By changing the approach from direct complex correction to geometric parameter extraction (ellipse center, axes, orientation), the system achieves accurate phase recovery with manageable computational complexity.
3Reliability
If I/Q data balancing is applied to correct amplitude and phase mismatch, then the reliability of sensing is improved, but the processing time increases
Solution Approach 1:
The system performs preliminary I/Q balancing by establishing the elliptical correction model once, and then applies the derived correction parameters efficiently to subsequent phase extraction operations. This preliminary setup reduces the processing time for each measurement while maintaining high reliability through accurate I/Q imbalance compensation.
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
The proposed I/Q data balancing scheme significantly improves the accuracy and reliability of phase information extraction, enhancing the performance of DAS systems and other sensing applications by correcting for I/Q imbalance and increasing the SNR, thereby improving the overall quality of sensed parameters like acoustic levels.
Implementation Method 1
at least one fiber optic coupler that receives backscattered light and that produces optical interferometry signals from the backscattered light
Implementation Method 2
photo-detectors that produce an electrical signal for each of said optical interferometry signals
Data Source
AI summary
A system includes an optical fiber and an interrogator to provide source light to the optical fiber. The system also includes a receiver coupled to the optical fiber. The receiver includes at least one fiber optic coupler that receives backscattered light and that produces optical interferometry signals from the backscattered light. The receiver also includes photo-detectors that produce an electrical signal for each of said optical interferometry signals. The system also includes at least one digitizer that digitizes the electrical signals. The system also includes at least one processing unit that calculates I/Q data from the digitized electrical signals, corrects the I/Q data based on ellipse fitting, determines phase values based on the corrected I/Q data, and determines distributed sensing parameter values based on the phase values.