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Submarine Sonar Detection

Submarine Sonar Detection. Wura Bamgbose, Brian Fletcher, Ryan LaFrance, Erin Walters School of ECE Georgia Institute of Technology ECE4007 L01 April 20, 2009. Project Overview. Sonar detection system Marine Robotics Group Navy competition. Navy Competition 2009. Bridge.

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Submarine Sonar Detection

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  1. Submarine Sonar Detection Wura Bamgbose, Brian Fletcher, Ryan LaFrance, Erin Walters School of ECE Georgia Institute of Technology ECE4007 L01 April 20, 2009

  2. Project Overview • Sonar detection system • Marine Robotics Group • Navy competition

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

  4. Technical Objectives • Amplify and detect a ping between 20-30 kHz • Determine the direction of origin of the ping • Communicate time delay with submarine’s main control system

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

  6. Measure Time Delay Pinger t2 t1 t1<t2

  7. Adjust Direction Pinger t2 t1 t1 = t2

  8. Physical Constraints Pic of BOX & mcu 6” 5.5”

  9. Sonar System Block Diagram Variable Gain Amplifier MCU Hydrophones ADC RS232 Pinger Measure Time Delay

  10. Amplifiers Variable Gain Amplifier MCU Hydrophones ADC RS232 Pinger Measure Time Delay

  11. LMC6484IN-ND Rail-to-Rail Output Swing (within 20 mV of supply rail 100 kW load) Excellent CMRR and PSRR: 82 dB Input impedance of 1 TΩ Quad operational amplifier

  12. Amplifier Design Performance • Target gain of 100dB • Three stage amplifier circuit • Low gain first stage to limit noise of the signal • Actual gain of 84dB

  13. Amplifier Output With 50uV Input

  14. Amplifier Output With 500uV Input

  15. Amplifier Schematic High-pass filter Low-pass filter Digital potentiometer

  16. Band-pass Filter Target -3dB frequencies of 18kHz & 42kHz Actual -3dB frequencies of 18kHz & 52kHz

  17. Microcontroller MCU Variable Gain Amplifier Hydrophones ADC RS232 Pinger Measure Time Delay

  18. Sonar System Controller Samples at 1 Msps Determines time delay in samples MCU ADC RS232 Measure Time Delay

  19. Determining Time Delay • Peak detection of signals on both channels • End detection of both signals • Cross correlation between start and end points • Cross correlation has a max at the time delay

  20. Signal Detection

  21. Cross-correlation V V2

  22. Auto-calibration t1 t2 t1 > t2  t1 = t2 Eliminates error from submarine design changes.

  23. Demonstration Electronics Laptop Pool Serial Cable Pinger Hydrophones

  24. Remaining Tasks Move cross-correlation code to MCU Design auto-calibration function Troubleshoot automatic gain control Test system in a pool

  25. Overall Analysis • Done well: • Good noise filtering • High gain • Sufficient sampling rate • Improvements: • MCU with more memory • Build circuit on one PCB to improve performance and reduce size

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