Snow / water level detection with distributed acoustic sensing integrated ultrasonic device
Aspects of the present disclosure describe distributed fiber optic sensing/distributed acoustic sensing (DFOS/DAS) systems, methods, and structures that advantageously provide rainfall intensity measurements along an entire length of a fiber optic sensor. using existing telecommunications optical fiber—which may be part of a multi-fiber, fiber optic cable—that may simultaneously carry live telecommunications traffic. The DFOS/DAS fiber optic sensing is used to obtain vibration and/or sound data from which rainfall intensity measurements may be made along the entire length of the DFOS/DAS fiber optic sensor.
1. A rainfall intensity estimation method operating in a distributed fiber optic sensing/distributed acoustic sensing (DFOS/DAS) system, the DFOS/DAS system comprising:
an optical sensor fiber;
a DFOS/DAS interrogator in optical communication with the optical sensor fiber,
the DFOS/DAS interrogator configured to generate optical pulses, introduce the generated pulses into the optical sensor fiber, and receive backscattered signals from the optical sensor fiber; and
an intelligent analyzer configured to
analyze the backscattered signals received by the DFOS/DAS interrogator and determine from the backscattered signals, vibrational activity occurring at one or more points along the optical sensor fiber;
the rainfall intensity estimation method comprising
operating the DFOS/DAS system and collecting backscattered signals including raindrop-induced vibration data from one or more points along a length of the optical sensor fiber over a period of time while determining rainfall intensity with a rain gauge; and
by the intelligent analyzer;
associating the raindrop-induced vibration data from one or more points along the length of the optical sensor fiber with the rainfall intensity determined with the rain gauge and determining a rainfall intensity at the one or more points along the length of the fiber optic sensor cable from the raindrop-induced vibration data associated with the rainfall intensity determined with the rain gauge.
2. The method of claim 1 further comprising:
by the intelligent analyzer, calibrating the rainfall intensity by comparing the determined rainfall intensity with a rainfall intensity determination made from a rain gauge.
3. The method of claim 1 further comprising:
by the intelligent analyzer, performing a frequency domain analysis on the DFOS/DAS sensing data using a maximum frequency value analysis and determining a maximum frequency value of the raindrop-induced vibrational activity.
4. The method of claim 3 further comprising:
by the intelligent analyzer, constructing a predictive model of rainfall intensity from the determined maximum frequency value.
5. The method of claim 4 further comprising by the intelligent analyzer, performing a relative cumulative frequency analysis on each frequency component of the raindrop-induced vibrational activity which sums the power spectrum of each frequency component to generate a cumulative frequency and determining a correlation between the cumulative frequency and rainfall intensity.
6. The method of claim 5 further comprising
by the intelligent analyzer, determining a category of rainfall intensity from the correlation between the cumulative frequency and rainfall intensity.
7. The method of claim 6 further comprising
by the intelligent analyzer, determining an intensity-duration-frequency relationship which describes a relationship between rainfall intensity, rainfall duration and a return period.
8. The method of claim 1 further comprising
by the intelligent analyzer, generating a map including location and rainfall intensity indicia.
9. The method of claim 1 wherein the optical sensor fiber includes one or more fiber loops along its length.