2023_programme: Development and the Hardware Architecture of a Densely Populated Large-Aperture 160-Element Ocean Acoustic Coherent Hydrophone Array

• Session: 12. Real-time underwater acoustic sensing and imaging systems: Advances- capabilities and results
  Organiser(s): Purnima Ratilal-Makris and Alessandra Tesei
• Lecture: Development and the Hardware Architecture of a Densely Populated Large-Aperture 160-Element Ocean Acoustic Coherent Hydrophone Array [invited]
  Paper ID: 1877
  Author(s): Radermacher Max, Schinault Matthew, Seri Sai Geetha, Mohebbi-Kalkhoran Hamed, Makris Nicholas, Ratilal Purnima
  Presenter: Radermacher Max
  Abstract: A densely populated 160-element large-aperture coherent hydrophone array system has been developed at Northeastern University (NU) to provide real-time instantaneous wide-area underwater acoustic monitoring. The array is connected to the research vessel or ship via a 600-meter-long faired tow cable to mitigate vibration and strumming along the array. The 192-meter-long acoustic section comprises four nested sub-apertures with spacing corresponding to half-wavelength design frequencies in Hertz of 250, 500, 1000 and 2000. Each hydrophone has a designated broadband preamplifier directly soldered to the element, providing a linear frequency response from 10 Hz to 50 kHz. The differential output signal from the preamplifier is next routed to a 32-channel, 24-bit Analog to Digital Converter (ADC), with a programmable sampling rate capability up to 100 kHz per element. Two Cat6A Ethernet cables run the length of the array, sending seamless acoustic and telemetry data to the forward non-acoustic section (NAS), where a pressure tolerant Fiber optic to Ethernet converter is equipped to send Fiber through the tow cable. An in-house designed pressure chamber is implemented to test hydrophones, preamplifiers, telemetry units, power boards and data switches to verify device performance, pre, during and post pressure exposure. The telemetry units, placed in both the forward and aft NAS of the array are used to provide real-time; depth, temperature, pitch, roll and yaw, which actively monitors the orientation and depth of the array. The NU array’s sub-apertures are connected via wet-mate connectors, allowing for a modular and interchangeable array system. The research, design, and fabrication of the array was conducted on NU’s Boston campus. The NU array has been sea tested in a range of depths from a couple hundred to over a thousand meters of water in the US Northeast coast in 2021, detecting an assortment of fish, whale, and man-made sounds.
• Corresponding author: Mr Max Radermacher
  Affiliation: Northeastern University
  Country: United States
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