Autonomous Sensor Platform

1. Autonomous Sensor Platform Jason Bryan Andrew McAllister December 5, 2002 ECE 345 Project Presentation

2. Main Objective Design a product for low- powered distributed sensing applications

3. Applications for ASP • Intruder detection • Detection of aircraft flying below radar • Mobile encampment sound perimeter • Mobile residential or urban motion detection • Meteorological Applications • Oceanic wave recording • Oceanic temperature readings • Balloon-borne sensing (GPS) • Seismic sensing (natural and intruder based) • Biological Surveying • Listen for specific bird calls • Triangulate and record animal “tag” pings • Space-based sensing • Planetary sensing • Orbiter would send out ASP units and one unit to interface the ASP network to a longer range transmitter to communicate with the orbiter and then Orbiter would transmit to Earth.

4. Features • BasicX-24 Microcontroller • A/D Input, Sleep mode, Visual Basic programming • Low power consumption • Easy networkability (wireless) • Versatile • Sensors easily substituted

5. Original Design Power • Solar Power w/ rechargeable battery • Power consumption of other subsystems • Voltage Regulation

6. Original Design Microcontroller • BasicX 24 • Sleep mode • onboard voltage regulator • A/D Converter • Other choices: TI, Basic Stamp

7. Original Design Communications & Networking • Linx digital TX/RX chips • Protocol • Synchronous TDMA

8. Original Design Sensor • Photodiode • Non-inverting Amplifier Amp Output: Off Amp Output: On

9. Project Milestones • Familiarized with the microcontroller • Prototype communication between two controllers with wires • Tested Linx chips, and replaced communications wires • Implement sensor amplifier, test output • Attach sensor to microcontroller • Improved networking programming, added visual basic software • Added sleep mode functionality

10. Project Build Power • Scrapped solar power to focus on networking aspect of the project • From spec, calculated system power consumption • Two voltage sources • 5v for TTL • 9v for amplifier (op-amp) and voltage regulator

11. Project Build Communications • Network protocol simulation using Simulink • Switched to Asynchronous TDMA • Clock on microcontroller shuts down in sleep mode • Multiple serial ports • Relaying

12. Network Protocol Program Flow

13. Project Build Sensor • Used photodiode for first build • Tuned amplifier on sensor for light levels • Constant gain of 10 • Varied resistor in parallel to photodiode to change the on/off threshold

14. Project Build Visual Basic Program • Allows computer to plug into any sensor and read network traffic • RS-232 protocol

15. Testing Amplifier tests • Max voltage output = TTL level into microcontroller • Wide light threshold for easy system testing • Otherwise would be tuned specific to the application

16. Testing Communications • Functional testing • First, function generator • Next, actual network data • RF chip range • Max network communication • speed vs. range

17. Testing Other Testing • Propagation Delay • Approximately 50 ms • LED on microcontroller on/off • Power Consumption • Actual vs. Theoretical

18. Testing

19. Successes • Low Power • Reliable communication • Independent modules and network infrastructure (ad-hoc network)

20. Recommendations Functionality to add: • Solar power / Rechargeable battery • Environmental Casing • Data coding and/or encryption on network • GPS • Better Antenna • More complex on-board process of sensor signal • System clock and onboard data storage