Aquatic Spectrometer

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Aquatic Spectrometer Turbidity Meter

• ECE 4007 L1, Group 8
• Paul Johnson
• Daniel Lundy
• John Reese
• Asad Hashim

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Introduction Background

• What is it?A device to detect the colour and
  clarity of a uniform flowing water sample
• How does it work?LEDs, a diffraction grating, a
  photo-detector array and an on-board PC
• Why do we need it?Demand from Aqua-culturists
  and Water Regulation Authorities for a cheap and
  easy to use device

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High Level Block Diagram
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Key Components

• Electronics OpticsControlling the LEDs,
  collimating the light, obtaining a diffraction
  pattern
• SoftwareDesigning code to interpret sensor data
  and provide useful information
• Mechanical AspectsDesigning an enclosure, water
  proofing circuits and designing an interface with
  existing pipe fittings
• InterfacingControlling LED power, and
  establishing two-way communication with photo
  sensor

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Electrical Characteristics
PARAMETER MIN TYP MAX
Supply Voltage 4.75V 5V 5.25V
Supply Current 450mA 725 1A
Operating Temperature -20 70C
Bandwidth 1Hz 30Hz
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Micron vs. Kodak Image Sensor
Micron Kodak
Cost 30 14
Speed 30fps 580fps
Resolution 1280 x 1024 126 x 96
Sensitivity 2.1V/lux-sec 22V/lux-sec
Notes Larger active area Discontinued
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Micron Image Sensor

• 10bit parallel data bus
• 1MHz 48MHz
• I2C control

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LED Control

• Independent LED control
• 3V IO lines
• OFF for dark current measurement
• Transmission measurement
• Scatter measurement

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Single Board Computer

• TS-7250 ARM9 Single Board Computer
• 200 MHz
• 32 MB RAM
• Programming in C
• Compiling with special ARM9 compiler obtained
  from vendor
• Networking software with wireless networking
  capabilities
• Four source files
• Main.c
• SquareWave.c
• Process.c
• Networking.c

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Software Flow Chart
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Photo Sensor Interfacing

• Sensor will be clocked at 1.3 MHz
• A 1 byte intensity value corresponds to each
  pixel on the sensor
• Sensor acts as a slave device controlled by the
  SBC
• Computer will communicate with the sensor through
  8 data lines.
• Each wavelengths intensity value must be
  multiplied by the inverse of the sensors white
  curve at that particular wavelength to normalize
  the overall spectrum

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Color Analysis - Obtaining Spectrum Values

• Intensity values are obtained via serial
  connection
• Values are stored in a vector
• Vector is divided into 3 (or more) regions
• Total intensity of each region is calculated
• The resulting regional intensities are compared
  to each other and stored as ratios
• Ratios are compared to predetermined ratios from
  known algae samples to determine the algae's
  growth stage

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Spectrum Division
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Turbidity Analysis

• Regional intensities from color analysis are
  summed to create an overall intensity
• The weaker the overall spectral intensity, the
  greater the turbidity
• Intensity to turbidity conversion will be
  calibrated by finding the spectral intensities of
  various samples of water with known turbidities

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Networking (if time permits)

• SBC sends resulting data to a centralized web
  server which can be accessed remotely by computer

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Scheduling
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Parts Cost Analysis
Part Cost
LEDs 9
SBC 184
CMOS Image Sensor 14
Optics Kit 10
Power Supply 20
Misc. Hardware 120
Total 357
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Marketing Cost Analysis

• Development CostsParts 357Labour 50,000
• Final Price 1499.99
• Includes parts, marketing, overhead, labour,
  testing and assembly
• Expected Revenue 374,998
• Expected Profit 91,445 (24.4)

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Conclusions

• ElectronicsControlled LEDs through power
  control module and designed photo sensor board
• OpticsDesigned collimating apparatus and
  positioned diffraction grating photo sensor
• MechanicalDesigned enclosure and interfaced with
  existing pipe fittings
• SoftwareProgrammed SBC to provide information on
  colour and clarity of water sample based on
  dummy data
• InterfacingHave yet to establish useful two way
  data communication between SBC photo sensor

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Questions?