Underwater Detection and Tracking Systems

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Underwater Detection and Tracking Systems

• Naval Weapons Systems

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Objectives

• Understand basic theory and operation of active
  and passive sonar systems
• Comprehend the basic principles of MAD
• Know the 3 basic types of transducers
• Comprehend the theory and operations of
  hydrophones
• Know the differences between active and passive
  sonar systems including the differences between
  active and passive systems, including adv/disadv
  of each.

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Objectives (cont.)

• Know various sonar systems TACTASS/Sonobuoys/Dipp
  ing Sonar/ SOSUS
• Comprehend the fundamentals of sound energy
  doppler and how it is used to determine target
  aspect and motion
• Know the methods of acoustic countermeasure
• Know the basic ASW capabilities of the major U.S.
  Navy platforms

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Introduction (Platforms)

• Surface Ships
• Advantages (versus helo/airplane)
• more available manpower
• greater time on station
• variety of detection equipment
• variety of available weapons and better fire
  control systems
• ability to operate in foul weather
• embarked LAMPS aircraft

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Introduction (Platforms)

• Surface Ships
• Disadvantages
• In submarines environment
• Relatively Slow
• Noisy
• ASW prosecution is protracted
• ASW Capabilities
• Ticonderoga, Arleigh Burke, Spruance
• Sensors Bow MountedSQS-53, TowedSQR-19
• SQQ-89 ties sensors together
• Weapons MK-46 torp being replaced with MK-50
• Oliver Hazard Perry
• SQS-56 or 53 bow mounted, same towed

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Introduction (Platforms)

• Aircraft Carriers
• Advantages
• NONE
• Disadvantages
• Same as for Surface Ships
• Aircraft Carrier is a High Value Target, its
  importance to naval operations requires many
  assets to be employed to protect it.

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Introduction (Platforms)

• Aircraft
• Advantages
• Speed
• ability to deploy sensors over a large area
• Surprise through use of passive detection systems
• Not in submarines environment
• Altitude increases radar horizon.

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Introduction (Platforms)

• Aircraft
• Disadvantages
• Low time on station
• Limited weapons capacity
• Limited range
• Vulnerable to weather

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Introduction (Platforms)

• Aircraft
• P-3 Orion
• Sensors MAD and upto 100 sonobuoys
• Weapons MK-4650 torps, MK-54 depth charges
• S-3 Viking
• Same but only 60 sonobuoys
• SH-60 Seahawk / SH-3 Sea King
• Sensors MAD, 25 sonobuoys, AQS-13F dipping sonar
• Weapons Same

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Introduction (Platforms)

• Submarines
• Advantages
• Shares the advantages of the target
• passive detection
• concealment
• less distracted by sound refracting properties of
  water
• Speed vs. Surface Ships
• Nuke subs can stay submerged for months

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Introduction (Platforms)

• Submarines
• Disadvantages
• To detect targets, subs must run deep
• To communicate, subs must be in shallow water
• Capable of high speed, but at the expense of
  increased noise levels
• Diesel subs must snorkel to recharge batteries

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Magnetic Anomoly Detection(MAD)

• Principle A metallic submarine disturbs the
  magnetic lines of force of the earth.
• The magnetic distortion - or anomoly - caused by
  a sub below the surface can be detected from the
  air above the sub.

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Basic Sonar Systems

• Active
• Echo Ranging Systems
• Passive
• Listening Systems
• Communications
• Underwater telephone (WQC-2)

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Transducer Theory

• Transducer Device for converting one form of
  energy into another.
• In sonar, electrical energy is transfromed into
  acoustic energy (oscillation of water moloecules
  through which sound travels)
• Three ways to change electrical energy into
  acoustic energy....

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Transducer Types

• Crystal Transducers
• Piezoelectric(strain in crystal creates
  electricity/ reverse true as well)
• Ceramic Transducers
• Elecrostrictive(electric field apllied across
  dielectric gt deforms it)
• Magnetostrictive Transducers
• Magnetostrictive(magnet deforms many materials
  usually attached to a diaphragm)

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Hydrophones

• Transducers
• Designed for reception only
• Magnetostrictive or Electrostrictive
• Lower power gt less temperature rise
• gt smaller/lighter

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Active Sonar Systems

• Searchlight Echo Ranging WW II
• Short Burst
• Highly Directional
• Physically Rotated
• Slow search, One target at a time, must traingt
  small trans gtlow power, high f
• Scanning Sonar
• Electronic 3600 search each transmission
• Larger transducers, more power, multiple targets

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Passive Sonar Systems

• Arrays
• Cylindrical, Spherical
• Conformal
• Towed
• Displays / Function Groups
• DEMON
• Broad Band
• LOFAR

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Advantages Disadvantages of Sonar Types

• Limitations of sonar due to the physical
  properties of sound travel in water
• Limitations of active and passive sonar in
  detection
• Limitations of active and passive sonar in
  tracking

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Other Sonar Equipment

• Tactical Towed Array Sonar (TACTAS)
• Sonobouys
• Passive
• Active
• Special purpose
• Dipping Sonar/Variable Depth Sonar
• Sound Surveillance System (SOSUS)

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Doppler

• How can you tell?
• Reverb What is it and why get it?
• Echo higher or lower freq
• Thus Up or Down Doppler
• Thus amount closing/opening

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Assignment 8

• READ
• USS VINCENNES CASE STUDY
• Workbook Ch 9 1,2,3,4,11,12,17