Snow / water level detection with distributed acoustic sensing integrated ultrasonic device
Aspects of the present disclosure describe snow/water level detection using distributed fiber optic sensing/distributed acoustic sensing (DFOS/DAS) and an integrated ultrasonic device that advantageously operates over existing optical telecommunications facilities carrying live telecommunications traffic—or optical facilities deployed specifically for such detection. DFOS/DAS monitoring of snow/water level advantageously monitors large areas with high sensitivity while exhibiting robustness to changing environmental conditions and employs a remote (utility pole or other mounting) mounted ultrasonic sensor/transducer that provides snow/water level data in real-time as a coded vibrational signal.
1. A distributed fiber optic sensing (DFOS) system comprising:
a length of optical sensor fiber;
a DFOS interrogator that generates optical pulses at one or more frequencies, introduces the generated pulses into the length of optical sensor fiber, receives backscattered signals from the length of optical sensor fiber, and determines from the backscattered signals acoustic/vibrational activity occurring at one or more points along the length of the optical sensor fiber;
an ultrasonic transducer positioned at a location along the length of the optical sensor fiber, said ultrasonic transducer positioned above ground level, and configured to:
determine a baseline distance between the ultrasonic transducer and the ground;
determine a measured distance between the ultrasonic transducer and the ground;
determine a snow/water level from a difference between the baseline distance and the measured distance; and
encode the snow/water level into a vibration pattern that is mechanically produced by the ultrasonic transducer, the mechanical vibration pattern producing mechanical vibrations in the length of optical sensor fiber for detection by the DFOS interrogator;
wherein said DFOS interrogator is further configured to determine the snow/water level from the backscattered acoustic signals;
wherein the DFOS interrogator is further configured to determine a location along the length of the optical sensor fiber at which the snow/water level is determined;
wherein the snow/water level is mapped to a vibration pattern in a one-to-one manner;
wherein the vibration pattern exhibits a center frequency and a duration; and
wherein the snow/water level is represented as a series of digits, wherein a ones digit of the snow/water level is D1, and the frequency of the vibration pattern F, is represented by:
F= 400 Hz+D1*50 Hz.
2. The system of claim 1 wherein a duration of the vibration pattern D vp , is represented by:
D vp =( D 2+1)*0.5 seconds
where D2 is the tens digit of the snow/water level.
3. The system of claim 1 wherein a snow/water level is pre-determined, and any snow/water level greater than the pre-determined level is mapped to a maximum pre-determined vibration pattern.
4. The system of claim 3 wherein the maximum pre-determined vibration pattern includes a 900 Hz frequency of vibration pattern for a 1 second duration.
5. The system of claim 3 wherein the DFOS system includes one or more of distributed acoustic sensing (DAS), distributed vibration sensing (DVS), and distributed temperature sensing (DTS).
6. The system of claim 5 wherein the optical sensor fiber is included in an optical cable that has a plurality of optical fibers.
7. The system of claim 6 wherein the optical cable includes a plurality of optical sensor fibers.
8. The system of claim 1 wherein the length of optical sensor fiber carries live telecommunications traffic simultaneously with the DFOS pulses and backscatter signals.