Direction-Finding Sonar System for Autonomous Submarine

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Direction-Finding Sonar System for Autonomous
Submarine

• Estee Amana, Nicole Rennalls, Mitcham Costley,
  Frederick Ealick
• ECE Department
• Georgia Institute of Technology
• ECE4007 L01
• October 22, 2008

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Project Overview
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Submarine
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Autonomous Underwater Vehicle
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Georgia Tech Marine Robotics Group
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Navy SEAL Practice Pool
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Navy Competition 2009
Bridge
Rooftop
Rooftop
Practice Side
Competition Side
Launch Platform
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Mission

• To build sonar system under 400 to complete
  Rooftop task for competition

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Design Objectives
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Detect Ping
2s
1.3ms

• Frequency 20-30kHz

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Determine Direction
Direction of Motion
60
Top View
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Communication
RS-232
Sonar Group
MRG Group
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Physical Constraints
Length 5
Width 5
Depth 2
Voltage 24VDC
Current 2A
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Time Delay
Receiver 2
t2
t1lt t2
t1
Receiver 1
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Technical Approach
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Sonar System Block Diagram
Variable Gain Amplifier
Linux SBC
Hydrophones
ADC
RS232
Pinger
Measure Time Delay
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Hydrophones
Linux SBC
Variable Gain Amplifier
Hydrophones
ADC
RS232
Pinger
Measure Time Delay
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Hydrophone Construction
Coaxial Cable
Metal Casing
Transducer
Metallic Membrane
Cost 150
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Amplifiers
Variable Gain Amplifier
Linux SBC
Hydrophones
ADC
RS232
Pinger
Measure Time Delay
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Filtering Amplifier Design and Testing
Cost 50
V
µV

• Four stage amplifier circuit
• Band pass filter to remove noise

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Amplification
Incoming Hydrophone Signal
Outgoing Amplified Signal
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Linux SBC
Linux SBC
Variable Gain Amplifier
Hydrophones
ADC
RS232
Pinger
Measure Time Delay
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Sonar System Controller
Cost 150

• Receives 1000 samples/channel
• Averages 10 highest 10 lowest samples
• Determines time delay

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Cross-correlation
V
V2
Time (sec)
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Auto-calibration
Pinger
Hydrophone
Direction of motion
Submarine
Goal Eliminate error from submarine design
changes, trace lengths, etc.
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Demonstration
Laptop
GT Pool
Serial Cable
Waterproof PVC Pipe
Pinger
Hydrophones
Electronics
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Current Status

• Construct and test amplifier prototype
• Implement existing embedded code
• Build hydrophones
• Construct amplifier on solder board
• Test automatic gain control

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Project Schedule
Test amplifier with pinger
Complete hydrophones
Mount hydrophones
Integrate system
Dec
Oct
Nov
Design PCB
Demonstration
Assemble circuit solder board
Control gain
Competition Date June 2009