1Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Team Acoustic Beamformer

Midway Design Review

11/25/2013

2Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Team Acoustic Beamformer

Nick DriscollEE

Rebecca McFarlandCSE

John ShattuckEE

Jimmy DanisEE

Name

3Department of Electrical and Computer EngineeringDepartment 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

4Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Specifications

5Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Updated Block Diagram

6Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

7Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

8Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Narrowing the Frequency Range

0 2000 4000 6000 8000 10000 120000

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f

|H

(f)|

• 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 “ᵢ”

9Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

10Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Current System Specifications• Mic spacing: 24cm

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F=450Hz

F=680Hz

BW=52°

BW=34°BW=50°BW=50°

BW=61°BW=61°

11Department of Electrical and Computer EngineeringDepartment 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

12Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

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

A/D Choice

14Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

MicrophonesSelected 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

15Department of Electrical and Computer EngineeringDepartment 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

16Department of Electrical and Computer EngineeringDepartment 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

17Department of Electrical and Computer EngineeringDepartment 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

18Department of Electrical and Computer EngineeringDepartment 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

19Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Individual Microphone Inputs

20Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Sum of Microphone Inputs

21Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Sum of Delayed Mic Inputs

22Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Unfiltered DFT of Inputs

23Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Filtered DFT of Inputs

24Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Cost Analysis

Items Purchased So Far

Remaining to purchase: PCBs

Item Purchased

Num. Purchased

Unit Price Total Cost

A->D Converter 1 $165 $165.00

MEMS Mics 3 $3 $9.12

Electret Mics 12 $.75 $14.20

Spent So Far $188.32

25Department of Electrical and Computer EngineeringDepartment 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)

26Department of Electrical and Computer EngineeringDepartment 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

27Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Schedule for 2014

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

Questions

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

Questions

30Department of Electrical and Computer EngineeringDepartment 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 +/- 3 db @ 94 dB SPL

• S/N Ratio 62 dB

31Department of Electrical and Computer EngineeringDepartment of Electrical and Computer Engineering Advisor: Professor Zink

Near-Field Beam Widths