Aquatic Spectrometer & Turbidity Meter

ECE 4007 L1, Group 8Paul JohnsonDaniel Lundy

John ReeseAsad Hashim

Introduction & Background What is it?

A device to detect the colour and clarity of a uniform flowing water sample

How does it work?LED’s, 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

High Level Block Diagram

Key Components Electronics & Optics

Controlling the LED’s, 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

Electrical Characteristics

PARAMETER MIN TYP MAX

Supply Voltage 4.75V 5V 5.25V

Supply Current 450mA 725 1A

Operating Temperature -20° +70°C

Bandwidth 1Hz 30Hz

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

Micron Image Sensor 10bit parallel data

bus 1MHz – 48MHz I2C control

LED Control Independent LED

control 3V IO lines OFF for dark current

measurement Transmission

measurement Scatter measurement

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

Software Flow Chart

BeginProgram

Compute turbidity

Set up Program

Store resultsDetermine colorTake in serial data

Turn LED's on andoff

SpecMain.c

SquareWave.c

Process.c

Networking.c

Establishconnection

Send data

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 wavelength’s intensity value must be multiplied by the inverse of the sensor’s white curve at that particular wavelength to normalize the overall spectrum

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

Spectrum Division

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

Networking (if time permits…)SBC sends resulting data to a centralized web server which can

be accessed remotely by computer

Scheduling

Parts Cost Analysis

Part CostLEDs $9

SBC $184

CMOS Image Sensor $14

Optics Kit $10

Power Supply $20

Misc. Hardware $120

Total $357

Marketing & Cost Analysis

Development Costs:Parts: $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%)

Conclusions Electronics

Controlled LED’s 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

Questions?