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Underwater Network Localization

Underwater Network Localization. Patrick Lazar, Tausif Shaikh , Johanna Thomas, Kaleel Mahmood University of Connecticut Department of Electrical Engineering. Outline. Background Objective Hardware/Software Methods Synchronous Asynchronous Range Test Noise Test Budget Future Work

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Underwater Network Localization

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  1. Underwater Network Localization Patrick Lazar, TausifShaikh, Johanna Thomas, KaleelMahmood University of Connecticut Department of Electrical Engineering

  2. Outline • Background • Objective • Hardware/Software • Methods • Synchronous • Asynchronous • Range Test • Noise Test • Budget • Future Work • Division of Roles • Timeline

  3. Background • Cannot use GPS because electromagnetic signals cannot propagate well through water • Use acoustic signals • Signal strength independent of conductivity of medium • Currently four commercial underwater localization techniques • Two research methods • Synchronous • Asynchronous

  4. Objective • Design a highly accurate localization system capable of being used on underwater vehicles. • Implement localization algorithms for real time testing. • Provide the AUV senior design group with an effective localization schematic that can be integrated into the AUV for underwater tracking.

  5. Hardware/Software • Six digital processing boards • Four anchor nodes • One tracking node • Six hydrophones • Six transducers • Four GPS tracking devices • Waterproof housing • Software : Code Composer Studio 5.1 DSP boards in waterproof housing.

  6. Synchronous Localization Method

  7. Synchronous Localization • Advantages of synchronous localization: • Able to service multiple AUV at once • Does not require continuous GPS signal to synchronize surface nodes • Disadvantages of synchronous localization: • Nodes must be on the surface initially to receive a GPS signal initially. • Any missed node signal means position can not be computed if working with the minimum node schematic.

  8. Synchronous Code Flow Diagram Start (nodes) Start (AUV) Init Modem Init Modem Listen for node calls Send Call when 4 calls received Wait for other nodes Position algorithm

  9. Asynchronous Localization Method

  10. Asynchronous Localization • Advantages of Asynchronous Localization: • Node clocks do not require synchronization with each other. • Extra timing measurements sent from other nodes can be factored into to calculations to provide better position accuracy. • Disadvantages of Asynchronous Localization: • The initiator signal must send out a delay factor long enough so no nodes send out signals at the same time. • Never field tested so actually accuracy improvement is unknown.

  11. Asynchronous Code Flow Diagram Start (nodes) Start (AUV) Init Modem Init Modem Localize Wait for AUV call Call N1 Call N2 Call N3 Call N4 Record N1 response Record N4 response Record N2 response Record N3 response Record time Position algorithm Send Response

  12. Range Test • The speed of sound travels at a faster rate in water than air. • It depends on water properties of temperature, salinity, and pressure. • As temperature of water increases, the speed of sound increases. • On average, the speed of sound travels at approximately 1500 m/s under water.

  13. Range Test Diagram Swimming Pool

  14. Noise Test • The range of the signal can be affected by the ambient noises and man made noises. • The variance calculated from the noise test is used to calculate the Time of Arrival (TOA) of the signal. Swimming Pool

  15. Budget • Currently all our hardware needs are handled by the Underwater Sensor Network Lab. • In terms of software the version of Code Composer studio we use is a free license version provided by the company. • At this time we have no plans to use the $1000 budget but in the future we may consider using funding to buy additional digital signal processing boards from Spectrum Digital if necessary.

  16. Future Work • Analyze the modem code supplied by UWSN Lab • Create algorithm code for both Asynchronous and Synchronous methods in C. • Implement tracking algorithms for localization of moving objects (if needed) • Conduct pool testing: • Range test of equipment • Determine delay time for more accurate calculations • Determine pool interference

  17. Project Roles

  18. Timeline

  19. Questions?

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