Lesson 11 - Underwater Detection and Tracking Systems
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Underwater Detection Underwater Detection and Tracking Systemsand Tracking Systems
Naval Weapons SystemsNaval Weapons Systems
Transducer TheoryTransducer Theory TransducerTransducer: Device for converting one : Device for converting one
form of energy to anotherform of energy to another Electrical energy into acoustic (oscillation of Electrical energy into acoustic (oscillation of
water molecules through which sound travels)water molecules through which sound travels)
TRANSDUCERAcoustic Signals
Electric Signals
Transducer PowerTransducer Power
Pressure of sound wave is limited by:Pressure of sound wave is limited by: Hydrostatic pressureHydrostatic pressure Cavitation pressureCavitation pressure
• Water vaporizes!Water vaporizes! Increasing power normally means Increasing power normally means
increased transducer array sizeincreased transducer array size How can we increase power from an array of How can we increase power from an array of
fixed size? fixed size?
Types of TransducersTypes of Transducers CrystalCrystal
Piezoelectric effect – converts pressure changes into Piezoelectric effect – converts pressure changes into electrical formelectrical form
Ceramic (Electrostrictive)Ceramic (Electrostrictive) An electric field is applied to polarize the transducer An electric field is applied to polarize the transducer
causing a slight change in shape (mechanical causing a slight change in shape (mechanical deformation)deformation)
MagnetostrictiveMagnetostrictive Magnetic field can cause materials to expand or Magnetic field can cause materials to expand or
contract (change shape)contract (change shape) Nickel rods placed in a magnetic field vibrateNickel rods placed in a magnetic field vibrate
Basic Sonar SystemsBasic Sonar Systems ActiveActive
Echo Ranging SystemsEcho Ranging Systems• Acoustic energy is transmitted, and the Acoustic energy is transmitted, and the
received signal is the echo from the targetreceived signal is the echo from the target ““Ping”Ping”
PassivePassive Listening SystemsListening Systems
• Dependant on receiving signals radiated Dependant on receiving signals radiated from the targetfrom the target
Advantages & Disadvantages Advantages & Disadvantages
Limitations of sonar due to physical Limitations of sonar due to physical properties of sound travel in waterproperties of sound travel in water
Active vs Passive sonar in detectionActive vs Passive sonar in detection Active vs Passive sonar in trackingActive vs Passive sonar in tracking
Questions?Questions?
HydrophonesHydrophones
Lighter than transducersLighter than transducers Designed for reception onlyDesigned for reception only Bearing information only, no rangeBearing information only, no range Much like a transducerMuch like a transducer
Electrostrictive Electrostrictive MagnetostrictiveMagnetostrictive
Other Sonar EquipmentOther Sonar Equipment Tactical Towed Array Sonar (TACTAS)Tactical Towed Array Sonar (TACTAS)
Passive systemPassive system Linearly spaced hydrophonesLinearly spaced hydrophones
• Heading, Temp, depth sensorsHeading, Temp, depth sensors
Other SonarOther Sonar
SonobouysSonobouys PassivePassive ActiveActive Special PurposeSpecial Purpose
Dipping SonarDipping Sonar Sound Surveillance System Sound Surveillance System
(SOSUS)(SOSUS) VISUAL!VISUAL!
Magnetic Anomaly DetectionMagnetic Anomaly Detection(MAD)(MAD)
Principle: A metallic submarine disturbs Principle: A metallic submarine disturbs the magnetic lines of force of the earththe magnetic lines of force of the earth
The magnetic distortion or anomaly The magnetic distortion or anomaly caused by a submarine below surface can caused by a submarine below surface can be detected from above submarinebe detected from above submarine
P-3C, SH-60BP-3C, SH-60B
Underwater CommunicationsUnderwater Communications
ELF TO UHF satelliteELF TO UHF satellite What is the disadvantageWhat is the disadvantage
Relatively Short RangeRelatively Short Range Water conditions, noise, reverberationWater conditions, noise, reverberation Sound ChannelsSound Channels
Ideal conditionsIdeal conditions 12,000 meters12,000 meters
Introduction (Platforms)Introduction (Platforms) Surface Ships (DDG, CG, DD, FFG)Surface Ships (DDG, CG, DD, FFG)
Advantages:Advantages:• more available manpowermore available manpower• greater time on stationgreater time on station• variety of detection equipmentvariety of detection equipment• variety of available weapons and better fire control variety of available weapons and better fire control
systemssystems• ability to operate in foul weatherability to operate in foul weather• embarked LAMPS aircraftembarked LAMPS aircraft
Introduction (Platforms)Introduction (Platforms) Surface ShipsSurface Ships
Disadvantages:Disadvantages:• NOT “in” the submarine’s environmentNOT “in” the submarine’s environment• Relatively Slow Relatively Slow • Noisy Noisy • ASW prosecution is protractedASW prosecution is protracted
Introduction (Platforms)Introduction (Platforms) Aircraft CarriersAircraft Carriers
Advantages:Advantages:• Same as for Surface Ships Same as for Surface Ships
Disadvantages:Disadvantages:• Same as for Surface ShipsSame as for Surface Ships• Aircraft Carrier is a High Value UnitAircraft Carrier is a High Value Unit• Its importance to naval operations requires many Its importance to naval operations requires many
assets to be employed to protect itassets to be employed to protect it
Introduction (Platforms)Introduction (Platforms) Aircraft (Aircraft (S-3S-3, P-3, SH-60B), P-3, SH-60B)
Advantages:Advantages:• SpeedSpeed• Ability to deploy sensors over a large areaAbility to deploy sensors over a large area• Surprise through use of passive detectionSurprise through use of passive detection• Not in submarine’s environmentNot in submarine’s environment• Altitude increases radar horizonAltitude increases radar horizon
Introduction (Platforms)Introduction (Platforms) AircraftAircraft
Disadvantages:Disadvantages:• Low time on stationLow time on station• Limited weapons capacityLimited weapons capacity• Limited rangeLimited range• Vulnerable to weatherVulnerable to weather• Not in submarine’s environmentNot in submarine’s environment
Introduction (Platforms)Introduction (Platforms) SubmarinesSubmarines
Advantages:Advantages:• Shares the advantages of the targetShares the advantages of the target
passive detectionpassive detection concealmentconcealment less distracted by sound properties of waterless distracted by sound properties of water
• Nuke subs can stay submerged for monthsNuke subs can stay submerged for months What is the limiting factor?What is the limiting factor?
Introduction (Platforms)Introduction (Platforms) SubmarinesSubmarines
Disadvantages:Disadvantages:• To detect targets, subs must run deepTo detect targets, subs must run deep• To communicate, subs must be shallowTo communicate, subs must be shallow• Capable of high speed, but at higher noise levelCapable of high speed, but at higher noise level• Diesel subs must snorkel to recharge batteriesDiesel subs must snorkel to recharge batteries
Questions?Questions?
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