Active Sonar Equation

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Active Sonar Equation
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Adapting Passive Ideas
Passive Case
From our Sonar
Target Strength describes the fraction of energy
reflecting back from the target
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Reverberation Noise
Reflections from non-target objects is greater
that noise.
Reverberation limited
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Active Sonar Materials

• Typical piezoelectric materials
• Quartz
• PZT -Lead zirconate titanate
• Barium Titanate

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Piezoelectricity
a
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Source Level for an Omni-directional projector
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Electrical Efficiency
Efficiency may range from 20 to 70 for most
sonar applications
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Directional Arrays
Principle of Reciprocity
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Transducer Sensitivity
How many dB for 1 volt input?
Input impedance
Manufacturers typically advertise based on SV.
To find SL, add 20logV.
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Example

• Compute the source level for an circular piston
  projector of diameter 1 meter radiating 10 kW
  acoustic power at a frequency of 15 kHz in water

Piston array
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Cavitation
(z in meters)
Pressure Threshold
S Tranducer Surface Area
Power Threshold