Modules for low-power time-synchronized vector sensor data acquisition from autonomous platforms
Abstract
Acoustic vector sensors have the capability of measuring both the pressure and particle velocity of an underwater acoustic field, which permits them to measure the directionality and other spatial characteristics of a sound field from a single point. Over the past two decades, a new generation of acoustic vector sensors, sold by the Wilcoxon Sensing Company, have become available with higherbandwidths and smaller volumes than previous vector sensors. The ability to measure low-frequency sound directionality from a compact and low-power package makes them appealing candidates for deployment from autonomous platforms, where the deployment of large-aperture volumetric hydrophone arrays is either undesirable or impractical. Two Office of Naval Research Task Force Ocean grants are currently seeking to incorporate these sensors into both autonomous deep-drifting (grant number N00014-21-1-2953; PI Aaron Thode) and Wave Glider platforms (grants number N00014-21-1-2791 & N00014-21-1-2558;PIs Luc Lenain and Karim Sabra). Both projects are currently using off-the-shelf data acquisition systems (DAQ) that consume high amounts of power and are not optimized for reading the simultaneous analog and digital data generated by these sensors. The DAQ systems are also vulnerable to clock drift, so no time-synchronized data is available for coherent passive acoustic signal processing between platforms deployed simultaneously.This proposal will build twelve (12) autonomous vector sensor data acquisition modules (VS-DAQM) for UCSD/SIO in collaboration with the Keyport NavalUndersea Warfare Center (NUWC), an organization that has already built a prototype low-power DAQ specifically designed for acquiring both acoustic and NAS data from Wilcoxon sensors. NUWC will expand the design of the board to enable archival data storage for upto two weeks of continuous recording from four channels, programmable hibernation and duty cycling modes, internal and external power management capabilities, and external time synchronization. These redesigned electronics will then be manufactured and packaged with a rechargeable lithium-ion battery system into a pressure case (1000 m depth limits) with a custom-designed cage mounted on oneendcap, that limits both mechanical vibration and flow noise contamination. The battery pack will permit at least 72 hours of continuous recording from the sensor, and up to two weeks under a duty cycle or with external power supplied. NUWC will retain two modules to permit further software development and debugging, and six additional vector sensors will be purchased to supplement existingsensors already owned by the university so that all twelve units have dedicated sensors.Existing commercial and previous DURIP-funded data acquisition systems cannot sample both analog and digital data, and do not allow external synchronization signals. Furthermore, there are strategic long-term advantages in permitting university oceanographic institutions to collaborate with a Navy lab that has practical experience working with these sensors. These advantages include an ability to easily customize and upgrade the DAQ software and memory capacity based on evolving sensor designs and applications, a flexibility not offered by commercial systems. The equipment has numerous additional future applications for other bottom-mounted and mobile platform applications, including an upcoming DARPA program for monitoring fish and crustacean settlement on artificial reef structures.This abstract is publicly releasable
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2023
- Source ID
- N000142312235
Entities
People
- Aaron Thode
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego