1. Direction-Finding Sonar System for Autonomous Submarine Nicole Rennalls, Estee Amana, Frederick Ealick, Mitcham Costley ECE Department Georgia Institute of Technology ECE4007 L01 December 1, 2008

2. Project Overview

3. Georgia Tech Marine Robotics Group

4. Autonomous Underwater Vehicle

5. Navy SEAL Practice Pool

6. Navy Competition 2009 Launch Platform Practice Side Competition Side Bridge Rooftop

7. Mission To build a sonar system under $400 to complete the “Rooftop” task, which improves upon previous design group efforts

8. Design Objectives

9. Detect Ping Frequency: 20-30kHz 2s 1.3ms

10. 60° Determine Direction Top View Direction of Motion

11. MRG Group Sonar Group RS-232 Ethernet Communication

12. Physical Constraints AvailableActual Length5”4” Width5”4.5” Depth2” Voltage24VDC Current2A0.2A

13. t1 t2 t1< t2 Time Delay Receiver #1 Receiver #2

14. Technical Approach

15. Sonar System Block Diagram Hydrophones Pinger Variable Gain Amplifier ADC Measure Time Delay RS232RS232 Linux SBC

16. Hydrophones Pinger Variable Gain Amplifier ADC RS232RS232 Linux SBC Measure Time Delay

17. Copper Disc Copper Tube Teflon Cable BNC Connector Epoxy Filling Hydrophone Construction Cost: $87 Piezoelectric Crystal Epoxy Filling Aluminum Foil

18. Hydrophone Testing PVC Pipe

19. Dr. T. Michaels’ Tank

20. Amplifiers Hydrophones Pinger Variable Gain Amplifier ADC RS232RS232 Linux SBC Measure Time Delay

21. MAX4196 Single-supply Rail-to-rail output (within 200 mV) Drawbacks:  Inconsistent gain across frequency band  Complexity associated with four stages  Gain adjustment difficult

22. Present Amplifier Design Cost: $20 EL8171

23. Intersil EL8171 Single-supply Rail-to-rail output (within 0 mV) Advantages:  PMOS input  Stable gain across frequency band  Fewer stages

24. Amplification

25. Automatic Gain Control Digital Potentiometer DS1802

26. Linux SBC Hydrophones Pinger Variable Gain Amplifier ADC RS232RS232 Linux SBC Measure Time Delay

27. Sonar System Controller Receives 1000 samples/channel Averages 10 highest & 10 lowest samples Determines time delay Cost: $150

28. Cross-correlation V Time (sec) V2V2

29. Cross-correlation of Real Data V V2V2 Sample #

30. Auto-calibration Goal: Eliminate error such as submarine design changes and trace lengths. Hydrophone Pinger Direction of motion

31. Previous Demonstration Proposal Hydrophones Waterproof PVC Pipe Pinger GT Pool Laptop Serial Cable Electronics

32. Current Test Configuration Hydrophone #1 Hydrophone #2

33. Signal Source

34. Transducers in Tank

35. Received Signals at 45°

36. Received Signals at -45°

37. Remaining Work Complete amplifier on solder board Complete power supply circuit Eliminate reflections for demonstration

38. Dec Project Schedule OctNov Test amplifier with pinger Control gain Demonstration Competition Date: June 2009 Mount hydrophones Assemble circuit solder board Complete hydrophones Integrate system