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Measuring Angular Variation of Target Strength for Simple Geometric Objects. CDR Ed Tucholski US Naval Academy Annapolis, MD. Reflected Wave. Object. Transmitter/ Receiver. Original Wave. Distance r. Drawing Source: Wikipedia. Active Sonar Equations.
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Measuring Angular Variation of Target Strength for Simple Geometric Objects
CDR Ed Tucholski
US Naval Academy
Annapolis, MD
Reflected Wave
Object
Transmitter/
Receiver
Original Wave
Distance r
Drawing Source: Wikipedia
Function of geometry and scattering direction
Noise Limited Case
Reverberation Limited Case
The reflected intensity (pressure) is dependent on the reflection, diffraction, and interference of sound scattered off the object.
Target Strength is highly dependent on the scattering angle.
The teaching point of this demonstration is to show the angular dependence.
For simplicity, we will measure
Filter
PreAmp
Target
1.15 cm
0.8 cm
Transducers
and Positioning System
Envelope Detector
Motor
Controller
Signal
Generator
40 kHz
25 kHz
Oscope
Oscope
Transducers

+
IN914 Diodes
LM741
Operational Amplifier
Envelope Detector
a
Data
Theory
a
Data
Theory
Data
Theory
L
Wavetek Model 29
Sine 40.04 kHz
18.1 V pp
SR560
Source A, AC Coupled
6 dB/oct band pass, 10k100k HZ
Low Noise
Gain = 20
Scope 1
Ch 1 10 V/div
Ch 2 50 mV/div
t = 10.0 ms
Scope 2
Ch 2 100 mV/div
t = 4.00 s
VXM1
72 s/rev