Post on 28-Aug-2020
6.101 Design Presentation
Helmuth Naumer and Mark Theng
Active Sonar Tracking System
Ideal End Result
Angle
Distance
Quick Background Information● Linear Array Beamforming
● I/Q signals
● Windowed Pulse
Introduction to Beamforming
Path LengthDifference
θ
Antenna Spacing
I/Q Signals
In Phase and Quadrature
Phase Manipulation
Pulse Design
Pulse Design
System Overview
CompleteSystem Architecture
BeamformingArray
Voltage ControlledPhase Shifter
All-PassFilter
Voltage ControlledAmplifier
Signal Conditioning
Sound
System Overview (Recap)
No feedback!
Angle Sweep (Triangle Wave Generator)
Thresholding → Square Wave
Integrator
Min/Max more important than frequency
Timer
Current Source
ThresholdingCharge on cap measures time
OUT
TICKNeed to prevent partial reset
← Reset
Timer
Current Source
ThresholdingCharge on cap measures time
IN
OUT
← Reset
OUT
TICK
Pulse Extender
Sampling
Drawing takes 2ms
Angle changes by 10mV -- acceptableTimer changes by 0.26V -- not acceptable
Need to sample timer voltage before drawing
Sampler
Sampler
Body Diode
Doesn’t work!
SamplerIN
OUT
Ensure current only flows in one direction
Current
Drawing
Angle
Distance
Drawing Circles
90° Phase Shift
Challenges● Noisy Signals
○ Interference and false echoes● Mathematical Precision
○ Accurate phase shifts for beamforming● Small Voltages
○ 5V USB power supply
Timeline
4/16 4/23 4/30 5/7Single Microphone
Beamforming PCB/Stretch Goals
Final Debugging/ Checkoff
Distance reading only
Thank You!
Voltage ControlledPhase Shifter
Trigger Generator
RC Timer
BJT Buffer
IN
OUT