Distributed Optical Fiber Rainfall Sensing With Deep Frequency Filtering

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Solution Overview

Problem

Current methods for rainfall and rainfall intensity detection, such as land-based weather stations and Earth-orbiting satellites, are limited by availability and accessibility, and there is an urgent need for improved, real-time, long-range, and wide-coverage sensors due to increasing frequency and intensity of precipitation events.

Innovation Solution

A Deep Phase-Magnitude Network (DFMN) is introduced for DFOS systems, dividing raw data into phase and magnitude components, using a Phase Frequency Learnable Filter (PFLF) for phase component filtering and standard convolution layers for magnitude, leveraging optical fiber sensing properties to enhance rainfall sensing accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If land-based weather stations and Earth-orbiting satellites are used for rainfall detection, then rainfall and rainfall intensity can be detected, but availability and accessibility are limited

Engineering Contradiction:
ImproveavailabilityVSAvoidaccessibility
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces traditional mechanical weather stations and satellite-based detection systems with distributed acoustic sensing technology using optical fibers. The optical fiber sensing system detects rainfall through acoustic vibrations and phase changes in the fiber, eliminating the need for physical weather station infrastructure and providing widespread accessibility without requiring direct contact with precipitation events.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces optical fibers as an intermediary medium between the rainfall event and the detection system. The optical fiber acts as a distributed sensor that converts mechanical vibrations from raindrops into optical phase changes, which can be measured remotely and transmitted through existing communication networks, thereby improving both availability and accessibility of rainfall detection data.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If traditional rainfall detection methods are used, then rainfall data can be obtained, but real-time capability and coverage range are insufficient

Engineering Contradiction:
Improvereal-time capabilityVSAvoidcoverage range
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent segments the optical fiber into multiple sensing points along its length, creating a distributed array of measurement locations. Each segment of the fiber can independently detect acoustic vibrations and phase changes, enabling simultaneous real-time monitoring across extensive geographic areas. This segmentation transforms a single-point measurement system into a distributed sensing network with both real-time capability and wide coverage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from traditional point-based or area-based rainfall measurement to a distributed linear sensing dimension. By deploying optical fibers along roads, power lines, or other infrastructure, the system creates a continuous one-dimensional sensing array that can monitor rainfall intensity at multiple locations simultaneously, effectively adding spatial dimensionality to real-time detection capability.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Area of stationary object

If distributed optical fiber sensing is used, then long-range and wide-coverage detection is achieved, but data processing complexity increases

Engineering Contradiction:
Improvecoverage rangeVSAvoiddata processing complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent extracts and isolates the phase component from the complex optical signal measurements, recognizing that phase changes contain the primary information about rainfall intensity and acoustic vibrations. By focusing analysis on the phase component rather than processing the entire complex signal, the system reduces computational complexity while maintaining the ability to detect rainfall events across long ranges and wide areas.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies different processing strategies to different components of the optical signal. Specifically, it processes the phase component separately from the amplitude component, using phase-based methods that are more suitable for detecting acoustic vibrations from rain. This localized processing approach allows the system to handle the complexity of distributed sensing data more efficiently by targeting computational resources at specific informative features.

Inventive Principle:
Principle #3Local quality

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 method achieves superior performance in rain intensity monitoring compared to state-of-the-art approaches, demonstrating effective and efficient real-time, wide-coverage rainfall detection.

Implementation Method 1

Distributed Acoustic Sensing (DAS) is a DFOS technology that uses fiber optic cables to detect acoustic vibrations

Methodology Applied
Scientific EffectAcoustic vibration detection: Vibration

Implementation Method 2

dividing raw DFOS sensing data into phase and magnitude components

Methodology Applied
Scientific EffectPhase change in optical signal:

Data Source

PatentUS20250277692A1Environmental perception using distributed optical fiber sensing: rain intensity monitoring by deep frequency filtering
Publication Date: 2025.09.04 NEC LABORATORIES AMERICA INC
  • US20250277692A1 patent drawing
  • US20250277692A1 patent drawing
  • US20250277692A1 patent drawing

AI summary

Disclosed are integrated DFOS/DAS systems, methods, and structures that advantageously enhances rainfall sensing by employing a Deep Phase-Magnitude Network (DFMN), dividing raw DFOS sensing data into phase and magnitude components, and performing targeted feature learning on each component independently. The disclosed systems, methods, and structures employ a Phase Frequency learnable filter (PFLF) for phase component filtering and utilize standard convolution layers on the magnitude component, advantageously leveraging inherent physical properties of optical fiber sensing. Finally, a phase-magnitude channel is formulated in a parallel network and subsequently fuses the features for a comprehensive analysis. Experimental results on collected fiber sensing data show that our systems and method according to aspects of the present disclosure perform favorably as compared with alternative, state-of-the-art approaches.