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DEVELOPMENT OF AN OCEANOGRAPHIC DRIFTER WITH IRIDIUM BI-DIRECTIONAL COMMUNICATION CAPABILITY

Universitat de les Illes Balears. DEVELOPMENT OF AN OCEANOGRAPHIC DRIFTER WITH IRIDIUM BI-DIRECTIONAL COMMUNICATION CAPABILITY. Master Thesis Master of Science in Electronic Engineering Miguel Martínez Ledesma Supervised by Alberto Alvarez Díaz Jaume Segura Fuster.

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DEVELOPMENT OF AN OCEANOGRAPHIC DRIFTER WITH IRIDIUM BI-DIRECTIONAL COMMUNICATION CAPABILITY

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  1. Universitat de les Illes Balears DEVELOPMENT OF AN OCEANOGRAPHIC DRIFTERWITH IRIDIUM BI-DIRECTIONAL COMMUNICATIONCAPABILITY Master Thesis Master of Science in Electronic Engineering Miguel Martínez Ledesma Supervised by Alberto Alvarez Díaz Jaume Segura Fuster University Of Balearic Islands (UIB) Palma de Mallorca, Spain, 29 February 2012

  2. Index • Introduction • Objective • Satellite Communications • Hardware Design • Software Design • Results • Conclusion • Future Work

  3. Introduction • Ocean Currents • Marine transportation, fishing, weather prediction, tracking of oil spills, search and rescue operations, etc.

  4. Introduction • Oceanographic Drifters • Instruments which move with the body of water surrounding them, and measure its location sequentially to compute an ocean current or “drift” (Lagrangian Drifting Buoys). • The most common drifter designs: • Surface Velocity Program (SVP) • Coastal Ocean Dynamics Experiment (CODE) CODE SVP

  5. Objective • Problem: • Standard drifters increase their endurance by incrementing the energy storage • Represent a threat for maritime traffic when buoys are drifted to near shore environments. • Solution: • Reduce the physical dimension and weight of a drifting buoy • Design a drifting buoy that minimizes its energy consumption • by using a bidirectional satellite communication system, • by incorporating low power and low quiescent current electronic devices, • by using several software energy saving techniques

  6. Satellite Communications • ARGOS • Unidirectional communication system • Transmitters can’t know the time window when the satellite is available for transmission, • No confirmation of correct data transmissions. • Gives transmitter position information using the Doppler Effect during the satellite orbit pass

  7. Satellite Communications • Iridium • Unique provider of truly global and continuous satellite voice and data communications with complete Earth coverage, including oceans • Much more energy efficient than competing systems (Argos and Orbcomm)

  8. Satellite Communications • Iridium Short Burst Data (SBD) service • Bi-directional message-based service • Transactions take place as conventional e-mails and attachments. • Low-cost and low-power transmission system • Iridium Pilot Project (DBCP) • Demonstrated Iridium SBD satellite feasibility in drifting buoys • Defined a standard message transmission format

  9. Hardware Design • Hardware Components • Controller System • Microcontroller STR711FR2 (ARM7TDMI) • Iridium SBD • Iridium Modem SBD 9601 • GPS Receiver • Garmin GPS-15H • Analog sensing • Battery voltage • Sea Surface Temperature • Power System • 12V 5.4Ah Alkaline Battery • 5 Volts DCDC regulator • 3.3 Volts LDO regulator • P-channel MOSFET transistors • Magnetic power-on circuit

  10. Hardware Design

  11. Software Design • Energy saving techniques: • File logging and file transmission methods • File transmission maximizes the number of bytes transferred at each network transaction • Number of transmissions minimized to reducing the overall consumption • Data compression algorithms • Reduces data to be transferred, and number of transmissions • Compression also reduces communication costs • GZIP and ZLIB (DEFLATE) algorithms

  12. Software Design • Transmission methods: • DBCP standard message format • Self-defined file transference protocol (SBDFile) • Self-defined file storage format • Dynamic execution • Remote upgrade of code using the built-in communication system • Increase the type and number of sensors that could be attached and applications that could be executed • Energy efficient code transmission when using GZIP compression

  13. Results • Mechanical Characteristics • 2.5 Kg weight • 39 cm height and 10 cm diameter • Endurance (theoretical): • 19.75 months measuring every 2 hours and transmitting a compressed file every day, • 10.75 months transmitting a message every time a measure is obtained • Costs: • 45% theoretical monthly savings using data compression • Prototype ~1.400 US$ manufacturing cost (1.800 US$ SVP)

  14. Results • Sea Tests Deployment together with a SVP drifter REP11-A Campaign: Deployment together with 2 CODE drifters

  15. Conclusions • New drifter design that minimizes risks for maritime traffic • Small size (39cm x 10cm diam.) and weight (2.5Kg) • Endurance ~20 months theoretical • Reduction of power consumption • Thanks to the use of the bidirectional capabilities of Iridium SBD • Low power microcontroller and low quiescent current power supplies and switches • Logging and transmission of files minimize the number of transfers to be performed. • Data compressions reduce the size of the files to be transferred. • Data compressions reduce also communication costs • Upgrade capabilities • Remote code reprogramming using dynamic execution features

  16. Future Work

  17. Acknowledments Mediterranean Institute for Advanced Studies, IMEDEA (CSIC –UIB) Marine Technology, Operational Oceanography and Sustainability (TMOOS) Department Electronic Systems Group (GSE), University of Balearic Islands (UIB) NATO Undersea Research Centre (NURC) Department of Systems and Technology

  18. Thank you!

  19. SVP Drifter • Experiments: • SVP (Surface Velocity Program) • WOCE (World Ocean Circulation Experiment)

  20. CODE Drifter • CODE or Davis style: • Coastal Ocean Dynamics Experiment (CODE)

  21. Drifters Comparison

  22. Satellite Systems comparison

  23. Low Power Consumption Theoretical Current consumption: 86,42uA

  24. Temperature Sensor

  25. Circuit Design

  26. Initialize External Devices Events generated by time Iridium GPS Watchdog Start Measure Position Measure Analog Send SVP Send File Network Connect Debug Event Scheduler File System Communication Memory Management Internal Devices Get GPS Position Microcontroller Internal Libraries Get Analog Data Create SVP message main Prepare File To Transmit Logic Behaviors initialize sleep schedude Save Measures measure process transmission Data Transmission configuration user interface Event Dispatcher Protocols Measure Time To WakeUp Commands Watchdog Stop Compression Sleep Software Architecture

  27. Compression • Compression and decompression methods of GZIP and ZLIB • Based on the DEFLATE compression algorithm • High compression rates, standardization, and source code available • Each block is compressed using a combination of the LZ77 algorithm and Huffman coding

  28. Dynamic Execution

  29. Reception software POP3 All Files Iridium SBD Server Email Server Local Disk Python Script SMTP Complete Files and Email Files SBD messages Iridium SBD Email Email Email Email Files Configuration FTP Server Complete Files Platform Data Retrieve

  30. Consumption Analysis

  31. Consumption Percentage Single measure transmission File transmission (24h) . Percentages of consumption with 2 hours measure period

  32. Life Time Analysis

  33. Costs Analysis

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