1 Department of Electrical and Computer Engineering Advisor: Professor Zink Team Acoustic Beamformer Midway Design Review 11/25/2013

2 Department of Electrical and Computer Engineering Advisor: Professor Zink Team Acoustic Beamformer Nick Driscoll EE Rebecca McFarland CSE John Shattuck EE Jimmy Danis EE Name

3 Department of Electrical and Computer Engineering Advisor: Professor Zink 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 Department of Electrical and Computer Engineering Advisor: Professor Zink 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 Department of Electrical and Computer Engineering Advisor: Professor Zink Updated Block Diagram

6 Department of Electrical and Computer Engineering Advisor: Professor Zink

7 Department of Electrical and Computer Engineering Advisor: Professor Zink

8 Department of Electrical and Computer Engineering Advisor: Professor Zink Narrowing the Frequency Range 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 Phonetic Vowel “”

9 Department of Electrical and Computer Engineering Advisor: Professor Zink

10 Department of Electrical and Computer Engineering Advisor: Professor Zink Current System Specifications Mic spacing: 24cm F=450Hz F=680Hz BW=52° BW=34° BW=50° BW=61°

11 Department of Electrical and Computer Engineering Advisor: Professor Zink Design Flaws to Be Addressed May not be a worry in considering the magnitudes within our beam

12 Department of Electrical and Computer Engineering Advisor: Professor Zink

13 Department of Electrical and Computer Engineering Advisor: Professor Zink 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)

14 Department of Electrical and Computer Engineering Advisor: Professor Zink 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

15 Department of Electrical and Computer Engineering Advisor: Professor Zink 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

16 Department of Electrical and Computer Engineering Advisor: Professor Zink 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

17 Department of Electrical and Computer Engineering Advisor: Professor Zink 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

18 Department of Electrical and Computer Engineering Advisor: Professor Zink Deliverable: MATLAB Simulations Taking 2 inputs into MATLAB and beamforming Used 2 computer mics to record test signals

19 Department of Electrical and Computer Engineering Advisor: Professor Zink Individual Microphone Inputs

20 Department of Electrical and Computer Engineering Advisor: Professor Zink Sum of Microphone Inputs

21 Department of Electrical and Computer Engineering Advisor: Professor Zink Sum of Delayed Mic Inputs

22 Department of Electrical and Computer Engineering Advisor: Professor Zink Unfiltered DFT of Inputs

23 Department of Electrical and Computer Engineering Advisor: Professor Zink Filtered DFT of Inputs

24 Department of Electrical and Computer Engineering Advisor: Professor Zink Cost Analysis Items Purchased So Far Remaining to purchase: PCBs Item Purchased Num. Purchased Unit PriceTotal Cost A->D Converter1$165$ MEMS Mics3$3$9.12 Electret Mics12$.75$14.20 Spent So Far$188.32

25 Department of Electrical and Computer Engineering Advisor: Professor Zink 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)

26 Department of Electrical and Computer Engineering Advisor: Professor Zink 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

27 Department of Electrical and Computer Engineering Advisor: Professor Zink Schedule for 2014

28 Department of Electrical and Computer Engineering Advisor: Professor Zink Questions

29 Department of Electrical and Computer Engineering Advisor: Professor Zink Questions

30 Department of Electrical and Computer Engineering Advisor: Professor Zink Microphones Analog Device MEMS Microphone Omnidirectional Analog output Frequency range: 100 Hz – 15 kHz Sensitivity -42 dB +/ dB SPL S/N Ratio 62 dB

31 Department of Electrical and Computer Engineering Advisor: Professor Zink Near-Field Beam Widths