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Intelligent Audio Localization System

Paul Belzak Mark Davis Travis Gage Nathan Styles Advisor: Hafiz Malik. Intelligent Audio Localization System. 4/23/10. Goals-. Create an intelligent surveillance system Construct Microphone Array to detect sound Correctly identify selected sounds

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Intelligent Audio Localization System

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  1. Paul Belzak Mark Davis Travis Gage Nathan Styles Advisor: Hafiz Malik Intelligent AudioLocalization System 4/23/10

  2. Goals- • Create an intelligent surveillance system • Construct Microphone Array to detect sound • Correctly identify selected sounds • Rotate apparatus in the direction of the audio event

  3. Block Diagram

  4. Responsibilities - Paul Belzak • Motor Controls • Motors • Pan 180° (& Tilt 30 °) • Operating Voltage: 12V • Speed: 1000-2180 rpm • Gears • Prevent jerky motion • Control at desired speed • Housing Design • Attach Microphone Array • Contain all wiring boards and components

  5. Responsibilities- Paul Belzak • Motor Controller Hardware • Microprocessor: PIC16F690 • Controlled by computer • Serial connection • SN754410 – Motor Driver • Quadruple Half-H Driver • +5V to +36v output to motor

  6. Responsibilities-Paul Belzak • Code • Use Matlab output signal and send to PIC16F690 • Send signal to motor driver to either rotate or stop • EMC Precautions • Keep wire length to a minimum • Use twisted wires on all long, multiple leads • Ensure the motor operation does not interfere with recording of signals

  7. Responsibilities: -Mark Davis • Microphone Array • 15 Electret Microphones • Arranged in cross • 9 across 7 tall • Powered by 5V • Driven by 10k resistor and 1uF capacitor

  8. Responsibilities: -Mark Davis • Electret Microphones • Only require a few volts due to self sustained charge • Mechanical vibrations cause changes in capacitance proportional to sound waves • Built-in J-FET Preamp/Buffer • Converts high impedance of electret element into low impedance • Causes polarization

  9. Responsibilities: -Mark Davis • Time Delay of Arrival (TDOA) • Technique used to measure distance and location of audio source • Small delay from one microphone to next • Delay used to calculate angle • Angle determines direction of sound • Once direction of sound is determined, position of system is adjusted accordingly

  10. Responsibilities: -Mark Davis • Source is different distance from each mic • Knowing distance between each mic, angle can be calculated based on time delay • Diagram of TDOA

  11. Project Requirements • Functional Requirements • Minimum Response Time – 3 seconds • 180° Horizontal Panning • 30 ° Vertical Tilt • Nonfunctional Requirements • Microsoft Visual Studio C++ • Matlab • PIC16F690

  12. Responsibilities: - Nathan Styles • Data Acquisition • Hardware Design • Software Design • Interface with Audio Identification • Sound Localization • Temporal Power Fusion • Microphone Pairs

  13. Data Acquisition – Block Diagram

  14. Responsibilities: -Nathan Styles • User Interface • CMD – Slow Setup • GUI – Future • Software Control • Board Configuration • Start Sampling • Interrupt when full • Write each channel to text file

  15. TPF Algorithm • Robust & Efficient • “Burst” Nature • Multiple Source • Steps: • TDOA Calculation • TDOA Histogram • Spatial Likelihood Function • SLF Fusion – Microphone Pairs

  16. Responsibilities -Travis Gage • Categorizing relevant signals • Compiled a list of 12 sounds related to crime • Unique Signals • Audio Identification • Mel-frequency cepstral coefficients (MFCCs) • Power spectrum of an audio signal • Approximates the human auditory system's response • Maximum sensitivity at about 3500 to 6000Hz is related to the resonance of the auditory canal

  17. Responsibilities -Travis Gage • MATLAB Derivation • Sampled at 16 kHz to minimize effects of aliasing • Thus for each tone with an actual frequency, measured in Hz, a subjective pitch is measured on a scale called the ‘mel’ scale • The mel-frequency scale has a linear frequency spacing below 1000 Hz and a logarithmic spacing above 1000 Hz

  18. Responsibilities -Travis Gage Block diagram of the MFCC processor

  19. Responsibilities -Travis Gage Spectral Bands vs. Frequency

  20. Sample Results Channel 0 Channel 1 Channel 2 Ideal Audio

  21. Major Milestones • Bad power supply • Charged caps biasing signal • Small steppers unable to rotate system • Large stepper motor burned out • Redesigned system on a smaller scale (3 Mic) • Rewired the system with smaller gauge flexible wire harness (CAT3)

  22. Future Tasks • Code Sound Localization Algorithm • Multi-Source Audio Localization • Implement full-scale design • Add Vertical Tilt

  23. Questions?

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