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Sound Targeting Platform

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Sound Targeting Platform CSE 477 Andrew Lenharth Michael Schaffer Quang Luu May 22, 2001 Introduction Multi-purpose platform Video conferencing Spotlighting Security ... – PowerPoint PPT presentation

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Title: Sound Targeting Platform


1
Sound Targeting Platform
CSE 477
  • Andrew Lenharth
  • Michael Schaffer
  • Quang Luu

May 22, 2001
2
Introduction
  • Multi-purpose platform
  • Video conferencing
  • Spotlighting
  • Security applications
  • Aims at sound source
  • Microphones pick up sound
  • Correlator locates source
  • Stepper motors drive arm

3
Physical Layout
Base Platform Rotating Platform Microphone
Placement
4
Modular Design
  • Three Stages
  • Audio Input Filter and Amplification
  • Correlation and Filtering
  • Aiming and Stepper Motor Drive Output

5
Stage One - Microphone
  • Microphones
  • Placed 54 samples apart (1.05 feet)
  • 1.3 grams

6
Stage One - Amplifier
  • Amplifiers
  • Amplify signal to line level for ADC

7
Stage One - Filter
  • Filter
  • Band-pass filter (200Hz 4kHz)
  • Fourth order Sallen-key filter
  • Chained second order low and high pass

8
Stage One ADC
  • ADC
  • Audio codec on XSV-300
  • Codec outputs 20-bit 48kHz samples
  • Threshold
  • Level above ambient noise
  • Eliminate noise
  • Output 2-bit (preserve phase information)

9
Stage Two - Correlator
  • Correlator
  • Sliding window correlator
  • 64 sample width
  • 108 sample window size
  • 3 stage pipeline

10
Stage Two Correlator
11
Stage Two - Threshold
  • Correlation Threshold
  • Convert 7-bit signed input to 5-bit output
  • Removes negative correlation

12
Stage Three - Aim
  • Aiming Algorithm
  • Scans correlation data as correlator runs
  • Finds max value and index of correlation
  • Accumulates 32 good max values before outputting
    index
  • Uses sliding level max criteria to only choose a
    max that is near levels of recent past maxes.

13
Stage Three Aim
14
Stage Three Motor Control
  • Stepper Motor Control
  • Two ICs Controller and Driver

15
Simulation
  • Simulated design in Matlab to experimentally
    discover good parameters.

Bit-depth of ADC 8 bits Correlator
Threshold 50 Averager Threshold 50 Averaged
Correlations 4 Correlator Width 64 Correlator
Window 128
16
Simulation (cont)
  • Refined correlator parameters to discover it is
    actually possible to find the source.

Bit-depth of ADC 2 bits Correlator
Threshold 80 Averager Threshold 50 Averaged
Correlations 1 Correlator Width 64 Correlator
Window 108
17
Parameters
  • Gain of amplifier 56.6 dB
  • Number of samples between microphones 54
    samples
  • Sampling rate of ADC 48 kHz
  • Band of band pass filter 200 Hz 4 kHz
  • Window size of correlator 108 samples
  • Width of correlator 64 samples
  • Bit-depth of correlator 2 bits
  • Bit-depth of ADC 20 bits
  • Value of Correlator Threshold minimum 0
    (variable)
  • Number of valid correlations before movement
    8,000

18
Reviewer Comments
  • Aiming Algorithm Jitter
  • Mover Module only allows motor to be driven if we
    didnt move one step last time
  • Frequency of the Step Signal
  • Mover Module drives stepper motor at 100Hz. (5kHz
    Max)

19
Current Status
20
Current Status (cont)
  • Correlator needs more testing
  • Aiming algorithm connection to accumulator needs
    to be implemented
  • Codec interface needs testing
  • Stepper motor control circuit needs to be built
    so it doesnt melt breadboard
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