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Measuring Angular Variation of Target Strength for Simple Geometric ObjectsPowerPoint Presentation

Measuring Angular Variation of Target Strength for Simple Geometric Objects

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Measuring Angular Variation of Target Strength for Simple Geometric Objects

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Measuring Angular Variation of Target Strength for Simple Geometric Objects

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Measuring Angular Variation of Target Strength for Simple Geometric Objects

CDR Ed Tucholski

US Naval Academy

Annapolis, MD

Reflected Wave Geometric Objects

Object

Transmitter/

Receiver

Original Wave

Distance r

Drawing Source: Wikipedia

Active Sonar EquationsFunction of geometry and scattering direction

Noise Limited Case

Reverberation Limited Case

Target Strength Geometric Objects

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 Geometric Objects

Pre-Amp

Target

1.15 cm

0.8 cm

Transducers

and Positioning System

Envelope Detector

Motor

Controller

Signal

Generator

40 kHz

25 kHz

O-scope

O-scope

Apparatus- Data Acquisition
- Serial to USB
- TekVisa
- Excel

Transducers

Cylinder 360 Geometric Objectso Target Strength

Target Strength is a Decibel Geometric Objects

Demonstration Geometric Objects

Wavetek Model 29 Geometric Objects

Sine 40.04 kHz

18.1 V p-p

SR560

Source A, AC Coupled

6 dB/oct band pass, 10k-100k 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

VXM-1

72 s/rev

Settings