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The M20 Particle Motion Sensor Bottom-Mounted System (also known as a Particle Velocity Sensor) is designed to measure 3-D particle motion and acoustic pressure in a broad range of environments – from within 1 metre of an air gun, to quiet ocean environments – in an easily-transportable package.

M20 Particle Motion Sensor Bottom-Mounted System (M20-110)

M20 Particle Motion Sensor Bottom-Mounted System (M20-110)

The heart of the system is the M20 hydrophone which includes a gyro-stabilized 3-dimensional orientation sensor, 3 dipole sensors and one omnidirectional acoustic pressure sensor.

M20 Particle Motion Sensor

M20 Particle Motion Sensor

Gain is factory set to optimise to the users requirements and in-band resonance can be adjusted to better support specific requirements. Bearing accuracy < 2 degrees relative to magnetic north.

The M20 Bottom Frame is a lightweight deployment apparatus specifically designed to accommodate the M20 hydrophone and a variety of support instruments. The stainless steel frame provides a sturdy, stable mounting solution for the M20, effectively de-coupling it from environmental vibration. The bolted frame and easily-detachable M20 sensor provide for convenient transport if space is at a premium.

Additional support on mounting, deploying, etc. can also be provided.

M20 Bottom-Mount System Typical Deployment Scenario

M20 Bottom-Mount System Typical Deployment Scenario

The illustration to the left shows a typical installation for the M20 Bottom-Mount System, deployed in an easy-to-access shallow water location while an off-shore vessel provides the necessary low-pressure sound source.

GeoSpectrum SoundView™ Post Processing Software

The M20-110 System is supplied with post-processing software.  SoundViewTM is a spectral processing and display application that includes omnidirectional and vector-sensor processing. SoundViewTM also has the ability to process real and complex heterodyned time-series data. SoundViewTM is a commercialized version of a sonar processing application originally developed for defense research.

SoundViewTM is compatible with Windows x64, Linux x64, and OSX.  Only one version is supplied with each license ordered.

SoundView Data Screen Shot

SoundView Data Screen Shot

The illustration to the left is showing direction of arrival for acoustic signals. Different bearings are indicated by different hues.

M20 Specifications

Useful frequency range 1 Hz to 3,000 Hz
Operating and survival depths 300 m
Operating and storage temperatures -40 to +70 °C
Size 127 mm diameter, 165 mm length
Fluid Compatibility Water
Sensitivity As required, see chart below for band shape on PV sensors, Omni is flat, typical response -180 dB re 1 μPa


Plot of Receive Sensitivity vs Frequency Capabilities Provided by the M20 Family of Hydrophones from GeoSpectrum Technologies Inc.

M20 Sensor X, Y, Z Nominal Response

The graph to the left shows Nominal Response in the X, Y and Z Axes of Receive Sensitivity vs. Frequency.

icon_PDFDownload the Particle Motion Sensor (M20-110) Brochure [UPDATED]
icon_PDFDownload the Particle Motion Sensor Standalone Sensor (M20-100) Specification Sheet
icon_PDFDownload the M20-040 Hydrophone Specification Sheet
icon_PDFDownload the M20-020 Hydrophone Specification Sheet

Contact GeoSpectrum Technologies for more information. To find out information on other GTI hydrophones, visit the Hydrophones page.

Relevant Papers

Click here to view a paper written by Dr. Bruce Armstrong and Paul Yeatman, co-founders of GeoSpectrum. This paper was published by Proceedings of the Institute of Acoustics.

Anthropogenic noise playback impairs embryonic development and increases mortality in a marine invertebrate

An Environmental Survey Around the Narec Offshore Anemometry Hub (Noah)-A Comparison between Acoustic Measurement Instruments.