1. Underwater Detection and Tracking Systems Naval Weapons Systems

2. Transducer Theory  Transducer: Device for converting one form of energy to another Electrical energy into acoustic (oscillation of water molecules through which sound travels) Electrical energy into acoustic (oscillation of water molecules through which sound travels) TRANSDUCER Acoustic Signals Electric Signals

3. Transducer Power  Pressure of sound wave is limited by: Hydrostatic pressure Hydrostatic pressure Cavitation pressure Cavitation pressure Water vaporizes!Water vaporizes!  Increasing power normally means increased transducer array size How can we increase power from an array of fixed size? How can we increase power from an array of fixed size?

4. Types of Transducers  Crystal Piezoelectric effect – converts pressure changes into electrical form Piezoelectric effect – converts pressure changes into electrical form  Ceramic (Electrostrictive) An electric field is applied to polarize the transducer causing a slight change in shape (mechanical deformation) An electric field is applied to polarize the transducer causing a slight change in shape (mechanical deformation)  Magnetostrictive Magnetic field can cause materials to expand or contract (change shape) Magnetic field can cause materials to expand or contract (change shape) Nickel rods placed in a magnetic field vibrate Nickel rods placed in a magnetic field vibrate

5. Basic Sonar Systems  Active Echo Ranging Systems Echo Ranging Systems Acoustic energy is transmitted, and the received signal is the echo from the targetAcoustic energy is transmitted, and the received signal is the echo from the target “Ping” “Ping”  Passive Listening Systems Listening Systems Dependant on receiving signals radiated from the targetDependant on receiving signals radiated from the target

6. Advantages & Disadvantages  Limitations of sonar due to physical properties of sound travel in water  Active vs Passive sonar in detection  Active vs Passive sonar in tracking

7. Questions?

8. Hydrophones  Lighter than transducers  Designed for reception only  Bearing information only, no range  Much like a transducer Electrostrictive Electrostrictive Magnetostrictive Magnetostrictive

9. Other Sonar Equipment  Tactical Towed Array Sonar (TACTAS) Passive system Passive system Linearly spaced hydrophones Linearly spaced hydrophones Heading, Temp, depth sensorsHeading, Temp, depth sensors

10. Other Sonar  Sonobouys Passive Passive Active Active Special Purpose Special Purpose  Dipping Sonar  Sound Surveillance System (SOSUS)  VISUAL!

11. Magnetic Anomaly Detection (MAD)  Principle: A metallic submarine disturbs the magnetic lines of force of the earth  The magnetic distortion or anomaly caused by a submarine below surface can be detected from above submarine  P-3C, SH-60B

12. Underwater Communications  ELF TO UHF satellite What is the disadvantage What is the disadvantage  Relatively Short Range Water conditions, noise, reverberation Water conditions, noise, reverberation Sound Channels Sound Channels  Ideal conditions 12,000 meters 12,000 meters

13. Introduction (Platforms)  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 systemsvariety of available weapons and better fire control systems ability to operate in foul weatherability to operate in foul weather embarked LAMPS aircraftembarked LAMPS aircraft

14. Introduction (Platforms)  Surface Ships Disadvantages: Disadvantages: NOT “in” the submarine’s environmentNOT “in” the submarine’s environment Relatively SlowRelatively Slow NoisyNoisy ASW prosecution is protractedASW prosecution is protracted

15. Introduction (Platforms)  Aircraft Carriers Advantages: Advantages: Same as for Surface ShipsSame 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 assets to be employed to protect itIts importance to naval operations requires many assets to be employed to protect it

16. Introduction (Platforms)  Aircraft (S-3, 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

17. Introduction (Platforms)  Aircraft 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

18. Introduction (Platforms)  Submarines Advantages: Advantages: Shares the advantages of the targetShares the advantages of the target passive detection passive detection concealment concealment less distracted by sound properties of water less 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?

19. Introduction (Platforms)  Submarines 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

20. Questions?