RS102A

INTRODUCTION TO
SONAR & ACOUSTIC SYSTEMS

SYNOPSIS

"Introduction to Sonar & Acoustic Systems" is a first coursefor engineers and other technologists who need a basic explanation of modernsonar systems function. The course will emphasize system functioning bymeans of examples and will only cover the most fundamental mathematics associatedwith sonar systems analysis.

ELIGIBILITY REQUIREMENTS

Junior Professionals with no related sonar experience and techniciansrequiring updating in sonar.

LEARNING OBJECTIVES

The principal objective of this course is to provide an introductorycourse for engineers and other technologists who require a basic knowledgeof underwater acoustics and basic sonar measurements, sonar system componentsand how these components function together to perform either active or passivesonar detection. The specific learning objectives are:

• To comprehend how sonar is used to measure distance, velocity, bearing and angular rates;
  
• To acquire skills in predicting simple sonar systems performance by using the sonar equations; and,
  
• To comprehend how each sonar subsystem sonar works in performing acoustic measurements and how these subsystems operate as a unit.

COURSE DESCRIPTION

This course is a basic course at the systems level and was designed forengineers and other technologists who have no previous sonar experienceto introduce them to the fundamentals of underwater acoustics and sonarsystems. The course begins by reviewing the phenomenology of the propagationof acoustic waves, their dispersion and reflection from objects. The processof detecting targets via sonar waves was given the acronym SONAR, whichwas derived from the phrase "sound detection and ranging". Thecourse begins by reviewing active and passive sonar and sonar equations.Basic acoustics including signal propagation, noise fields and the waveequation are developed. Target and other sources and sound levels are discussedas an introduction to receive arrays and array gains. Ocean acoustic propertiessuch as propagation of sound, background noise, and reverberation are described.

The last part of the course looks at the functioning and operation ofa typical sonar system. Performance is discussed as a function of targetstrength, signal excess and system figure-of-merit and the basic tendentsof detection theory. Finally, examples of a sonar systems performance areillustrated for both active and passive sonar systems. This presentationof case studies shows methods of trading-off basic sonar parameters to determineand improve system performance. This course provides a comprehensive introductionto the topics of acoustics and sonar as they apply to the anti-submarinewarfare problem. Concepts and a thorough understanding of the sonar equationsare stressed. Real-world examples are discussed.

COURSE OUTLINE

Introduction Active/Passive Sonar Sonar Equations Basic Acoustics Signal Propagation Noise Fields Wave Equation Sources & Source Level Receive Arrays & Array Gain Propagation & Transmission Loss Reflection & Scattering Ocean Properties Acoustic Propagation in the Ocean Ray/Wave Theory Ducts (Surface/Deep) Deep Sound Channel Convergence Zone Absorption Transmission Loss in the Ocean

Ocean Noise Ambient Own-ship Reverberation Surface Bottom Volume Target Strength Signal Excess Figure-of-Merit Detection Theory Active Detection Performance Passive Detection Performance

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