Sonobuoy Technology for Air ASW and Beyond

This two-day course will provide a broad introduction to the technology and operation of sonobuoys used by the US and NATO for airborne anti-submarine warfare (Air ASW).

Although sonobuoys have been in use by the US Navy, allies, and competitors for over 50 years the technology remains a mystery.  This course will provide you with an in-depth background about sonobuoy technology including why they are used, how they are constructed, and examples of the different types of sonobuoys over time. We'll also discuss the types and roles of manned and unmanned aircraft and systems that are critical to understanding the opportunity and limitations of current sonobuoy technologies.  By the conclusion of this course you will understand the unique roles sonobuoys play in the overall ASW scenario and be able to discuss where sonobuoy technology may need to be focused in the future.

Including two real world tragedies: the loss of Malaysia Airlines Flight 370, MH370, in 2014, and OceanGate's Titan submersible disaster (2023) we'll also talk about sonobuoys for search and rescue (SAR) and some of the occurrences in TV and the movies.  We will summarize with the future of electro-mechanical miniaturization, cellphones, LEO satellites, smart sensors and the possibilities of semi-autonomous systems of sonobuoys.

1. Review of Underwater Acoustics and Sonar Principals: Description of ASW and Air ASW platforms, and signal processing. Review of sound propagation, and the sonar equation, basic concepts and units, passive and active sonar, performance and prediction

2. Types of sonobuoys: Passive and active types of hydrophones, and arrays bathythermogarph buoys, communications buoys, passive and active sonobuoys

3.  Sonobuoy More Than a Shiny Can: unique qualities of sonobuoys for ASW, sonobuoy fundamentals construction and subsystems, discussion of the major electro-mechanical components of sonobuoys including float envelope, sea anchor, dampers, and controlled drag elements. 

4.  Using Sonobuoys: packaging, air launch, water entry, activation, depth, command and control, and data exfiltration. Review of dynamic forces on sonobuoys from air launch, deceleration, water impact, to sensor deployment and activation.  Sonobuoy motion and how subsurface currents help to stabilize sonobuoys.

5.  Sonobuoy Beamforming and Array Signal Processing: DIFAR or point array processing, vertical arrays, horizontal arrays, and planar arrays

6.  Beyond ASW: Sonobuoy technologies for communications, search and rescue (SAR), hydroacoustic data on nuclear explosions, industrial, and scientific research. The limitations and opportunities of the current and future types of sonobuoys for marine biology and environmental assessment, geoscience, maritime safety and security, monitoring climate change, and beyond.

• Underwater sound propagation and the sonar equipment
• Airborne anti-submarine warfare (Air ASW)
• Major sonobuoy subsystems including transducers, signal processing, and communications
• Mechanics and hydrodynamics of sonobuoys
• Passive and active sonobuoys and transducers
• Non-ASW uses of sonobuoy technology:  How passive and active sonobuoys have been portrayed to the public and in movies. 

Seibert Murphy has over 40 years’ experience in sonobuoy technology and related disciplines underwater acoustics, sonar, and signal processing.  Mr. Murphy received a B.S. degree in physics from Purdue University, and an M.S. degree in systems engineering from the Catholic University of America.  His master's thesis was on the hydrodynamic stability of underwater tethered planar arrays.   He has served as an airborne anti-submarine warfare (Air ASW) sonar operator, engineer in advanced sonobuoy technology, including development of new sonobuoys and transducers.  At the Johns Hopkins University Applied Physics Laboratory (JHU/APL) Mr. Murphy was senior staff and the principal investigator on sonobuoy array processing.  He is the owner of Guide Star Engineering, LLC (GSE LLC), a member of the Audio Engineering Society (AES), and the current president of the Acoustical Society of America (ASA), DC Chapter.