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Team Acoustic Beamformer

Midway Design Review. Team Acoustic Beamformer. 11/25/2013. Team Acoustic Beamformer. Name. Jimmy Danis EE. Nick Driscoll EE. Rebecca McFarland CSE. John Shattuck EE. Project Goal. Objective: scan and localize a single person’s

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Team Acoustic Beamformer

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  1. Midway Design Review Team Acoustic Beamformer 11/25/2013

  2. Team Acoustic Beamformer Name Jimmy Danis EE Nick Driscoll EE Rebecca McFarland CSE John Shattuck EE

  3. Project Goal Objective: scan and localize a single person’s voice among outside conversation and background noise in real time Primary Use: conference rooms (teleconferences) Secondary Uses: small lecture halls, security Other Moral Implications: • Help increase conference/lecture productivity • Can help the hard of hearing • Could act as an eavesdropping device

  4. Specifications Operating range: minimum 1m, maximum 3m Minimum spanning angle range: 130 degrees Gives us a scanning distance of at least 2.27 meters at minimum distance Can comfortably fit 3 people for a teleconference call within this range Typical width of meeting room chairs: 47cm Can allow 43cm spacing between participants Minimum Beamwidth: 38.1° (to not intercept both voices in main beam) Operate within the human voice frequency spectrum Ideally 300 Hz- 3kHz

  5. Updated Block Diagram

  6. Narrowing the Frequency Range Phonetic Vowel “ᵢ” • Look at Phonetic Vowels • Have distinct peaks in magnitude across the frequency range known as “formants” • First is highest in magnitude, provides a low frequency window

  7. Mic spacing: 24cm Current System Specifications F=450Hz BW=61° BW=52° BW=61° F=680Hz BW=50° BW=34° BW=50°

  8. May not be a worry in considering the magnitudes within our beam Design Flaws to Be Addressed

  9. A/D Choice Selected the MC DAQ USB-204 System Requirements: 8 channels >30 kHz Sample Rate USB Interface USB-204 Specifications: 8 channel analog I/O 500 kHz total sample rate, 62.5 kHz/channel 12-bit depth USB 2.0 Full Speed (12 Mbps) (240 kHz * 12 bits = 2.88 Mbps)

  10. Microphones • Selected different mics – CMA-4544PF Electret • Condenser Mic from CUI Inc. • Better sensitivity (-44 dB+/-2 dB) • Better Voltage Rating (3-10 V) • Wider frequency response (20 Hz- 20kHz) • Easier form factor to work with • Previous mics needed PCBs • These plug right into breadboard • Faster, easier, better specs • Also Omni-Directional

  11. Deliverable: Mics into A/D Hook up 2 microphones Have those feed into A/D Show that 2 microphone inputs can be recovered on the computer DEMO

  12. Software Custom real-time software Microsoft Windows application Built in C++ Using open source Aquila DSP library to do DSP calculations Investigating whether we want a matrix math library as well Currently using Microsoft Windows API to play back sound Could also use open source API (CoreAudio) to play back sound so that the code is platform agnostic

  13. Deliverable: Software Get overall framework together Start hooking up pieces by showing we can load a WAV file and play it back Exercises playback code DEMO

  14. Deliverable: MATLAB Simulations Taking 2 inputs into MATLAB and beamforming Used 2 computer mics to record test signals

  15. Individual Microphone Inputs

  16. Sum of Microphone Inputs

  17. Sum of Delayed Mic Inputs

  18. Unfiltered DFT of Inputs

  19. Filtered DFT of Inputs

  20. Cost Analysis Items Purchased So Far Remaining to purchase: PCBs

  21. CDR Deliverables Nick: Optimize microphone amplifiers Increase to 8 microphone input channels to A/D Rebecca: Take A/D as input into software Save out wave file Jimmy: Design Band Pass Filter Spherical Wave Algorithm John: Spherical Wave Calculations Team: End-to-End System (take input from multiple mics, pass through A/D to computer, perform beamforming functions on inputs)

  22. FPR Deliverables Nick: PCB Fabrication for Amplifiers/Microphone Combinations for all 8 inputs Rebecca: Implement scanning, Final Real-Time Analysis Jimmy: Scanning algorithm in MATLAB, Widen frequency Range John: Widen frequency range (Algorithms) Scanning technique algorithms Team: End-to-End system, beamforming performed on 8 microphone inputs with a polished, professional presentation

  23. Schedule for 2014

  24. Questions

  25. Questions

  26. Analog Device MEMS Microphone Omnidirectional Analog output Frequency range: 100 Hz – 15 kHz Sensitivity -42 dB +/- 3 db @ 94 dB SPL S/N Ratio 62 dB Microphones

  27. Near-Field Beam Widths

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