Multilayer Cyclic Coding for Distributed Optical Fiber Sensing
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Solution Overview
Problem
Distributed optical fiber sensing systems face limitations in achieving high spatial resolution and long sensing distances due to the trade-off between pulse duration and peak power, leading to a deteriorated signal-to-noise ratio and increased computational complexity and cost for real-time decoding and long-distance measurements.
Innovation Solution
A multi-layer cyclic coding method is introduced, where each layer is encoded with a different cyclic codeword, allowing for a long cyclic codeword to be replaced by combining several short ones, reducing computational complexity and storage requirements while improving signal-to-noise ratio and extending sensing distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a long cyclic codeword is used to improve sensing distance and signal-to-noise ratio, then measurement precision and reliability are improved, but device complexity and computational complexity increase
Solution Approach 1:
The patent divides a long cyclic codeword into multiple shorter cyclic codewords arranged in layers. Each layer uses a shorter codeword (e.g., 7-bit or 3-bit) instead of one long codeword, reducing the computational burden of decoding while maintaining the equivalent coding gain through the product of individual layer gains
Solution Approach 2:
The patent transitions from a single-dimensional long codeword to a multi-dimensional layered structure. The coding is organized across multiple layers (e.g., first layer, second layer), where each layer contributes to the total coding gain. This dimensional transformation allows the system to achieve the same or better signal-to-noise ratio with reduced computational complexity at each layer
2Length of stationary object
If pulse duration is extended to improve sensing distance, then sensing distance is improved, but spatial resolution deteriorates
Solution Approach 1:
The patent changes the temporal parameters of the optical pulses by using coded pulse sequences instead of single long pulses. The coding scheme allows the system to use longer effective pulse durations for extended sensing distance while maintaining spatial resolution through the decoding process that separates overlapping pulse responses
3Measurement precision
If peak power is increased to improve signal-to-noise ratio, then signal-to-noise ratio is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs periodic transmission of coded pulse sequences instead of continuous high-power pulses. The cyclic nature of the codewords allows for periodic repetition of pulse patterns, enabling signal averaging and correlation processing that improves signal-to-noise ratio through temporal integration rather than peak power enhancement
Data Source
AI summary
Aspects of the present disclosure describe a multilayer coding method for physical value measurements in which a multi-pulse pattern is generated through several layers, each of which is encoded with a different cyclic codeword. The total coding gain is the product of the gains of each layer advantageously allowing a long cyclic codeword to be replaced by combining several short cyclic codewords. Of particular advantage, methods according to the present disclosure provide better signal-to-noise characteristics, longer sensing distances and lower computational complexity particularly suitable for high-performance and cost-effective distributed optical fiber sensing (DOFS).