Underwater Network LocalizationPatrick Lazar, Tausif Shaikh, Johanna Thomas, Kaleel

Mahmood

University of Connecticut Department of Electrical Engineering

OutlineBackgroundObjectiveHardware/SoftwareMethods

SynchronousAsynchronous

Range TestNoise TestBudgetFuture WorkDivision of RolesTimeline

BackgroundCannot use GPS because electromagnetic

signals cannot propagate well through waterUse acoustic signals

Signal strength independent of conductivity of medium

Currently four commercial underwater localization techniques

Two research methodsSynchronousAsynchronous

ObjectiveDesign 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/SoftwareSix digital processing boardsFour anchor nodesOne tracking nodeSix hydrophonesSix transducersFour GPS tracking devicesWaterproof housingSoftware : Code Composer Studio 5.1

DSP boards in waterproof housing.

Synchronous Localization Method

Synchronous LocalizationAdvantages of synchronous localization:

Able to service multiple AUV at onceDoes 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 DiagramStart

(nodes)

Init Modem

Send Call

Wait for other nodes

Start(AUV)

Init Modem

Listen for node

calls

when 4 calls

received

Position algorithm

Asynchronous Localization Method

Asynchronous LocalizationAdvantages 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 DiagramStart

(nodes)

Init Modem

Wait for AUV call

Record time

Send Respons

e

Start(AUV)

Init Modem

Call N1

Call N2

Call N3

Call N4

Record N1

response

Record N2

response

Record N3

response

Record N4

response

Localize

Position algorithm

Range TestThe 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 TestThe 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

BudgetCurrently 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 WorkAnalyze the modem code supplied by UWSN LabCreate 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 equipmentDetermine delay time for more accurate

calculationsDetermine pool interference

Project RolesTausif Shaikh (EE)

Synchronous and

Asynchronous algorithm

implementation in C

Analysis of pool test results

Website maintenance and updates

Johanna Thomas

(EE)Synchronous

and Asynchronous

algorithm implementatio

n in C

Analysis of pool test results

Coordinator of data and

results collected by each part of

the team

Patrick Lazar (EE)

DSP Board Programming

Hardware setup

Website maintenance and updates

Kaleel Mahmood (EE)

DSP Board programming

Hardware setup

Main communication

between design group and advisor

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

•Field testing of algorithms.

•Algorithm comparison analysis.

April

•Integration of localization with other groups.

•Algorithm comparison analysis.

May

•Complete integration of localization with an AUV.

Questions?