Hydrophone arrays
Locate submarines, track marine mammals and even to study global climate change by detecting temperature differences.
Hydrophone arrays
Hydrophone arrays are widely used in underwater security to monitor underwater threats, detect unauthorised vessel movements and protect critical infrastructure such as underwater pipelines and cables. Hydrophone arrays are also used in seismic surveys for oil and gas exploration. And they are increasingly used in oceanographic research to study underwater acoustics, ocean currents, marine mammal communication and the behaviour of marine species.
What are hydrophone arrays?
A hydrophone array is a collection of hydrophones, which are underwater microphones designed to detect and record sound waves in the water. These arrays can vary in size and complexity, from a small group of hydrophones to large arrays consisting of hundreds or even thousands of individual sensors.
Hydrophone arrays are typically arranged in specific configurations to capture sound waves from different directions and distances. The arrangement of hydrophones allows the location, tracking and analysis of underwater sound sources. The capabilities of these hydrophone arrays can be enhanced by adding accelerometers to a hydrophone array. These accelerometers provide additional information about the direction of movement of water particles in response to sound waves.
Measuring pressure with a hydrophone is a unidirectional measurement, whereas measuring the acceleration or velocity of water particles can provide a unique wave direction, improving the accuracy of determining the direction of incoming acoustic signals. This combination of pressure (sound pressure) and acceleration measurements forms what is known as a 4-component (4C) hydrophone array.
Source: University of Rhode Island
Working principle
In this picture, sound is transmitted from the ship and reflected from the submerged submarine.
The reflected sound first reaches hydrophone A, then hydrophone B and finally hydrophone C.
The difference in arrival times between the hydrophones in the array is used to determine the direction of the submarine.
Streamer array's
For the development of the Streamer Array's, Somni has worked on three types of sensors:
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Hydrophones (Somni does not sell standard hydrophones, please contact us for more information)
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Accelerometers for 4C arrays (see also Accelerometers)
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Pressure sensors for depth sensing (see also Pressure Sensors)
The Ministry of Defence had high requirements for the fiber optic hydrophone arrays. One of these requirements was that the noise level of the hydrophone arrays had to be lower than sea state zero.
The development of this type of sensor is very challenging. But Somni proved once again that no challenge is too great! A special hydrophone array was developed for this application to meet the requirements of the Ministry of Defence. Not only is the development of this type of sensor challenging, but the testing of these sensors is also quite demanding. Fortunately, there are good test facillities near Somni.
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