Spectrum Digitizers and AWGs Used in New Underwater Acoustics Lab
— Dr. Neilsen
GROSSHANSDORF, HAMBURG, GERMANY, Sept. 14, 2022 /EINPresswire.com/ — The Acoustics Research Group of the Department of Physics and Astronomy at Brigham Young University, Utah, USA, has chosen the digitizers and generators of state-of-the-art signals from Spectrum Instrumentation to form the heart of its new underwater acoustics laboratory. The new lab is a big step forward in research into sound waves moving through water as it effectively provides a miniaturized version of the ocean. Experiments are possible on the behavior of sound waves in different layers of water and their reflections on the most diverse ground materials of the ocean such as rocks, sand or mud. Miniaturization means that the highest precision is required from the measurement equipment, as the experimental results are later scaled to indicate what would happen in the real world.
The new laboratory water tank is rectangular and measures 3.6 m long by 1.2 m wide with a maximum water depth of 0.91 m. The research consists of using a hydrophone for signals or chirps generated by an arbitrary waveform generator (AWG), the spectrum model M2p.6546-x4. This PC board generates signals with 24 V output oscillations which are then amplified before being broadcast by a hydrophone. After passing through the reservoir, the signals are picked up by another hydrophone and processed by a Spectrum M2p.5932-x4 digitizer board. The transmitter and receiver are each held by a robotic arm that positions and orients them in the water so that the source and receiver can be positioned as needed.
The tank allows for experiments on how the seabed affects the sound waves bouncing off it. A pure rocky bottom will have a different effect compared to sand or mud or layers of different material. “It’s even more complicated, explains Dr. Traci Neilsen, professor in charge of the project, because the water is not homogeneous. Changes in temperature and salinity alter the speed of sound and cause waves to bend, similar to how a mirage occurs. We plan to examine the impact of changes in water temperature on machine learning to locate sound sources. These reservoir studies are more reproducible, efficient and cost-effective than ocean experiments and will allow us to develop techniques that can then be tested on ocean data.
Adam Kingsley, PhD student responsible for acquisition software, said, “We chose Spectrum products because they have proven to deliver the extremely high level of accuracy and synchronization that we need. Because this reservoir is actually a miniaturization of a huge body of water, precise timing is essential for the results to be meaningful when scaled.
The pair of Spectrum PCIe cards are housed in an external PCIe chassis in the main control console, precisely synchronized using a Spectrum Star-Hub module. The configuration includes a second identical pair of cards in a second chassis which can be triggered in operation by the first chassis.
This large-scale experiment requires much higher frequencies in the kilohertz range than would be used in the ocean. The digitizers and AWG cards have a high 16-bit resolution and can even sample and output at rates of 40 mega-samples per second respectively, while lag between channels is less than 100 pico-seconds. This provides the high precision required for experiments. The two arms of the UR10e robot, as well as signal generation and data acquisition, are all controlled by a custom LabVIEW software program created by Adam Kingsley called “Easy Spectrum Acoustics Underwater” (ESAU).
A key part of the experimental setup is to model the open ocean, so special anechoic panels from Precision Acoustics on the sides of the tank reduce reflections. An important innovation was the design of a filtration and circulation pump by John Ellsworth, who is the supervisor of research laboratories in BYU’s Department of Physics and Astronomy. This pump keeps the water clean without creating bubbles in the tank, which are a major source of noise. With all of these preparations in place, impulse responses could be measured, making it easier to remove noise from readings when an experiment is in progress. The precision of Spectrum PC boards with a signal-to-noise ratio (SNR) of over 71 dB ensures that impulse response elimination yields accurate experimental results.
Dr Neilsen added: “This new lab has been built to allow research students to design and perform their own experiments as part of their academic studies. My first graduate student, Cameron Vongsawad, and I thought carefully about what equipment to buy, as it was important that everything was sturdy and easy to use as this setup will be in operation for many years to come. Like many other labs, we appreciate the unique five-year warranty offered by Spectrum Instrumentation, as it means we can rely on their products for years to come.
The press kit can be downloaded at https://spectrum-instrumentation.com/download_files/press_kits/Press_Kit_New_Underwater_Acoustic_Lab.php
About Spectrum Instrumentation
Spectrum Instrumentation, founded in 1989, uses a unique modular concept to design and produce a wide range of over 200 digitizer and generator products as PC boards (PCIe and PXIe) and standalone Ethernet units (LXI). In 30 years, Spectrum has won customers around the world, including many A-brand industry leaders and virtually every prestigious university. The company is headquartered near Hamburg, Germany, known for its 5-year warranty and exceptional support that comes straight from the design engineers. For more information about Spectrum, visit www.spectrum-instrumentation.com
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