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Aquatic Spectrometer & Turbidity Meter

Aquatic Spectrometer & Turbidity Meter. Preliminary Design Review ECE 4007 L1, Group 8 Paul Johnson Daniel Lundy John Reese Asad Hashim. Introduction & Background. What is it? A device to detect the colour and clarity of a uniform flowing water sample

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Aquatic Spectrometer & Turbidity Meter

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  1. Aquatic Spectrometer & Turbidity Meter Preliminary Design Review ECE 4007 L1, Group 8 Paul Johnson Daniel Lundy John Reese Asad Hashim

  2. Introduction & Background • What is it?A device to detect the colour and clarity of a uniform flowing water sample • How will it work?LED’s, a diffraction grating, a photodetector 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

  3. High Level Block Diagram

  4. Electronic Specifications • LED’s (Luxeon LXHL-NWG8)Switched on/off via control signal, through 350mA Continuous Power Supply • CMOS Sensor (Kodak KAC-9630)Triggered to capture via control signal through serial interface • Power Considerations

  5. Electronic Block Diagram

  6. Optics - Prism • Higher cost • Larger area required Source:http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/prism.html

  7. Optics – Diffraction Grating • Inexpensive • Easily positioned • 500 grooves/mm • Resolution of 0.633nm Source:http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/gratcal.html

  8. Optics – Physical Placement • Requires fine sensor adjustment • +/-0.1mm tolerance for 1st order maxima • Active sensor area is the limiting factor

  9. Mechanical Hardware Secure the optical and electronic components to the enclosure Facilitate and ease the alignment process Keep the system calibrated, mechanically, as long as possible

  10. Two Slits Assembly

  11. CMOS Sensor Assembly

  12. Base Support Plate Slotted holes provide movement and alignment adjustment for the distance between the diffraction grating and CMOS sensor Mates to the Vertical Support Plate

  13. Vertical Support Plate Three Point Precision Mount (Springs and Screws) Middle screw hole utilizes negative pressure via lock down screw to secure position Provides minute adjustments in the horizontal direction Mates to both the Base Support Plate and CMOS Mount Plate

  14. CMOS Mount Plate Attaches the CMOS Sensor to the plate via standoffs Provides the vertical alignment adjustment

  15. Single Board Computer • TS-7250 ARM9 Single Board Computer • 200 MHz • 32 MB RAM • Programming in C • Four source files: • SpecMain.c • SquareWave.c • Process.c • Networking.c • Compiling with ARM9 compiler obtained from vendor • Networking software with wireless networking capabilities Source:http://www.embeddedarm.com/Manuals/ts-7250-manual-rev2.2.pdf

  16. Software Flow Chart

  17. Photo Sensor Interfacing • Sensor will be clocked at 10 MHz • A 1 byte intensity value corresponds to each pixel on the sensor • A serial image consists of a data out pin d[0] and three synchronization pins: d[1],vsync, and hsync Source: Kodak KAC-9630 data sheet

  18. Normalizing the Spectrum • The white light spectral response of the sensor is not perfectly flat • Other factors such as LED spectral output also add distortion to white light response • These inconsistencies are accounted for by performing spectral analysis with no sample present and multiplying the measured response of samples by the inverse of the white light response Source: Kodak KAC-9630 data sheet

  19. Color Analysis - Obtaining Spectrum Values • Intensity 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

  20. Spectrum Division Visual representation of spectral division

  21. 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 turbidly conversion will be calibrated by finding the spectral intensities of various samples of water with known turbidities

  22. Cost Analysis

  23. Conclusions • ElectronicsSchematics drawn, parts en route, prototyping in progress • OpticsParts en route, calculation & experimentation stage • MechanicalMechanical drawings done, in fabrication stage. • SoftwareSBC delivered, preprogramming stage

  24. Questions?

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