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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

Measuring Angular Variation of Target Strength for Simple Geometric Objects

CDR Ed Tucholski

US Naval Academy

Annapolis, MD


Active sonar equations

Reflected Wave Geometric Objects

Object

Transmitter/

Receiver

Original Wave

Distance r

Drawing Source: Wikipedia

Active Sonar Equations

Function of geometry and scattering direction

Noise Limited Case

Reverberation Limited Case


Target strength
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


Apparatus

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


- Geometric Objects

+

IN914 Diodes

LM741

Operational Amplifier

Envelope Detector


Square plate

a Geometric Objects

Data

Theory

Square Plate


Circular plate

a Geometric Objects

Data

Theory

Circular Plate


Cylinder

Data Geometric Objects

Theory

Cylinder

L


Cylinder 360 o target strength
Cylinder 360 Geometric Objectso Target Strength



Demonstration
Demonstration Geometric Objects


Settings

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


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