AST

Acoustic Systems Trainer

The Acoustic Systems Trainer (AST) for SONAR


The study of sonar principles and techniques are equally as demanding as the study of radar principles and techniques.


With the appropriate scaling of the system operational parameters, such as an increase in frequency of operation (hence a shorter wavelength), and the subsequent reduction in the dimensions of the acoustic tank, lower power requirements in the active sonar mode, and a P.C. interface with software to perform the sonar signal analysis, a real-time bench top Acoustic Systems Trainer for SONAR has been designed and manufactured for underwater studies.


The system is comprised of a control Console, containing the CW and Pulse gating electronics, and the hardware/software-processing (Sonar Signal Analyzer - SSA) interface with the computer.


AST Console and Acoustic Tank with Target Transport System & Heated Tank

The transparent Acoustic Tank is constructed from acrylic material, measuring 1.2 meters in length, 600mm deep, and 600mm wide, with a capacity for 400 litres of water. The built-in heater can be used to vary the water temperature which is monitored by a submersible probe thermometer.


A variety of active targets are mounted on a reversible, variable speed Target Transport System, which enables the Doppler principle to be demonstrated.


The passive targets consist of a set of scale model, brass propellers, with 2, 3, 4, and 5 blades, mounted on a variable speed

motor unit with integral gearbox.


Acoustic damping material can be added to the tank for mill pond quiet experiments to be conducted with the sensitive hydrophone, and spectrogram software.


Both narrow beamwidth and wide beamwidth high frequency transducers can be used; allowing beam interaction to be clearly shown on the P.C. based virtual instruments.

NPL Transducer Polar Diagram

Beam steering circuitry controls the phase drive to the transducers.

Digital Oscilloscope display

Active and passive targets are studied, and the SSA - Spectrum Analyzer, displays the signatures of a selection of passive targets.

Digital Spectrum Analyzer

Sonar Techniques and Principles


The foundation of the sonar principle is based upon the physics of sound waves, and all of the influences affecting the sound waves as they travel through the medium of water.


Due to the wide range of variable electronic parameters, such as PRF, Pulse Width, Tx Frequency and Variable Phase outputs, the Acoustic Systems Trainer (AST) is ideally suited to a development environment where the what if? scenario, can be explored in complete safety.


A university MSc degree dissertation has already been written using the early AST(Mk III) as a development platform at the University of Plymouth.


Some of the techniques and principles which can be demonstrated (and developed further) with the Acoustic Systems Trainer, include:


  • Speed of sound in water

  • Temperature effects on the speed of sound.

  • The single element Transducer

  • Transducer resonant frequency

  • Two-element array

  • Transducer beamwidth

  • Passive SONAR

  • Active SONAR

  • CT-FM SONAR

  • Parametric SONAR

  • Depth finding

  • The Doppler Effect

  • Underwater communications

  • Active target profiles

  • Passive target FFT signatures

  • Shallow water backscatter

  • Beam formation

  • Beam steering

  • Volume scattering & cavitations

  • Dielectric phase shift

  • ASW and Stealth

AST Installations


The AST is currently installed in a number of universities, and naval training establishments in the following countries:


  • Bangladesh

  • Brazil

  • Canada

  • China

  • India

  • Indonesia

  • Korea

  • Malaysia

  • Netherlands

  • Norway

  • Oman

  • Pakistan

  • Saudi Arabia

  • Singapore

  • Taiwan

  • United Kingdom

  • United States of America

  • Vietnam

The largest installation of seven Acoustic Systems Trainers provides for fourteen students working in pairs.

Instruction Materials


The AST has a comprehensive Laboratory Manual, Instructor Guide, and User Guide, data acquisition software, and a complete set of accessories, including:


  • Transducers

  • Hydrophone with Integral pre-amp

  • Sound Library

  • Active/Passive Targets

  • Target Transport System

  • Temperature Monitoring

  • Acoustic Damping Material

  • Detector/Filter

  • BNC Cables & T Pieces

  • SONAR Course on CD