Patrick Lazar, Tausif Shaikh, Johanna Thomas, Kaleel Mahmood Underwater Network Localization Patrick Lazar, Tausif Shaikh, Johanna Thomas, Kaleel Mahmood University of Connecticut Department of Electrical Engineering

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

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

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.

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.

Synchronous Localization Method

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.

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

Asynchronous Localization Method

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.

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 N2 response Record N3 response Record N4 response Record time Position algorithm Send Response

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.

Range Test Diagram Swimming Pool

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

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.

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

Project Roles Tausif Shaikh (EE) Johanna Thomas (EE) Synchronous and Asynchronous algorithm implementation in C Analysis of pool test results Website maintenance and updates Johanna Thomas (EE) Coordinator of data and results collected by each part of the team Patrick Lazar (EE) DSP Board Programming Hardware setup Kaleel Mahmood (EE) DSP Board programming Main communication between design group and advisor

Timeline September Project Statement. Background research in existing Localization methods. October Project specifications. Additional localization research. Coding DSP C November Code composer studio setup and completion of tutorial on coding in DSP C. Finalize implementation plans. December Ranging and noise pool tests using two nodes. Coding DSP C algorithms. Timeline January Ranging and pool tests using two nodes. Hardware setup of remaining nodes. Field testing of algorithms . February Field testing of algorithms. Algorithm comparison analysis. March April Integration of localization with other groups. May Complete integration of localization with an AUV.

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