1. 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

2. Outline Background Objective Hardware/Software Methods Range Test
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 N2 response
Record N3 response
Record N4 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 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

18. 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.

19. Questions?