Multi-Band DAS Signal Interleaving with Correlation Phase Alignment
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Solution Overview
Problem
In multi-carrier interleaving DAS systems, the phase relationships for the same location along the optical sensor fiber using different carriers are random, leading to challenges in producing a meaningful interpolated output.
Innovation Solution
A method is employed to align the phase signals of different frequency bands in the time domain, rotate them to the same direction, and combine them to produce an interleaved output signal suitable for firmware implementation, while maintaining phase continuity and improving signal-to-noise ratio (SNR).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If correlation-based polarization combining is used in multi-carrier DAS, then signal-to-noise ratio is improved, but phase relationships become random and meaningless interpolated output is produced
Solution Approach 1:
The patent applies preliminary action by performing phase alignment and rotation operations before the correlation-based polarization combining process. Specifically, the system rotates the polarization and band diversities into a direction of one with highest averaged power, and aligns the same location along the length of the optical fiber sensor from different bands to a same clock cycle. This preliminary phase alignment ensures that when correlation combining is subsequently applied, the phase relationships are preserved and meaningful interpolated output is produced while maintaining improved signal-to-noise ratio.
2Productivity
If multiple frequency bands are combined for SNR improvement, then sampling rate increases, but phase continuity is lost and output becomes meaningless
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the phase and polarization parameters of multiple frequency bands before combining them. The system rotates each band's polarization diversity into a common direction and aligns temporal parameters so that the same location from different bands corresponds to the same clock cycle. This parameter transformation maintains phase continuity across bands while enabling higher sampling rates through multi-band combination.
3Measurement precision
If phase signals from different bands are aligned in time domain, then meaningful interpolated output is produced, but system complexity increases
Solution Approach 1:
The patent replaces complex mechanical or hardware-based phase alignment mechanisms with software-based digital signal processing operations. Specifically, the system uses correlation methods and digital rotation algorithms to align phase signals from different frequency bands in the time domain. This substitution of digital processing for physical alignment mechanisms achieves meaningful interpolated output while managing system complexity through flexible, programmable operations rather than fixed hardware configurations.
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 method achieves a meaningful interpolated output with improved SNR and faster sampling rate, suitable for firmware implementation, by aligning phase signals and combining them in a way that maintains phase continuity and enhances sensitivity.
Implementation Method 1
DFOS/DAS system that uses a Rayleigh backscattering optical signal
Data Source
AI summary
Methods for a DFOS/DAS system that uses a Rayleigh backscattering optical signal, employs a transmitter/interrogator that generates optical signals with multiple frequencies and directs the generated optical signals into a optical fiber sensor, receives, by a receiver, backscattered signals, processes each frequency received and combines and interleaves frequency bands for improved signal-to-noise and a faster sampling rate. The receiver uses a correlation method for polarization and band combining/interleaving, that rotates the polarization and band diversities into a direction of one with highest averaged power, by aligning a same location along the length of the optical fiber sensor from different bands to a same clock cycle, apply correlation methods to the band diversities, to rotate the same location from the different bands to the same direction, and combines sub-bands allocated for SNR improvement, and delays resulting bands and interleaves them.