This document describes an acoustic modem design for underwater sensor networks. It introduces the challenges of underwater acoustic communication compared to radio and optical methods. It then describes the design of an adaptive acoustic modem, including a sensor network architecture using the modem. Applications of underwater sensor networks are discussed such as environmental monitoring. Simulation and analog test results are presented. The conclusion discusses the benefits of an adaptive modem and digital hardware platform to enable reliable underwater communication while saving energy.

1. VISVESVARAYA TECHNOLOGICAL UNIVERSITY
BELGAUM-590 018, KARNATAKA.
ARKA Educational and Cultural Trust(R)
Jain Institute of Technology, Davangere
Department Of Electronics and Communication Engineering
8th sem B.E. Technical Seminar on:
“ACOUSTIC MODEM DESIGN FOR UNDERWATER
SENSOR NETWORKS”
UNDER THE GUIDANCE OF
Dr.NAGARAJA B G M.Tech.,Ph.D BY,
POOJA J BOOSNUR
4JD12EC031
1

2. Contents
• Introduction
• Why Acoustic Communication
• Adaptive Acoustic Modem Design
• Underwater Sensor Network Architecture
• Applications
• Simulation and Analog Test Results
• Conclusion
• References
2

3. Introduction
• UNDERWATER sensor networks have a wide range of
oceanographic applications.
• It consist of a varaible number of sensors and vehicles that are
deployed to perform collaborative monitoring tasks over a
given area.
3

4. Why Acoustic Communication?
• Radio waves tend to fade rapidly in underwater environments.
To cover large distances ,huge antennas and high transmission
power are required.
• Optical communication is possible but only in clear water at
relatively short distances.
• Acoustic communication is challenging due to large and
variable multipath delay spread, Doppler shifts, and long
propagation delays .
4

5. Adaptive Acoustic Modem Design
5

6. Underwater Sensor Networks
Communication Architecture
6

7. Applications
• Environmental monitoring
• Undersea explorations
• Disaster prevention
• Assisted navigation
• Distributed tactical surveillance
• Mine reconnaissance
7

8. Detecting Underwater Objects
• A robot crawler carries a modem, a camera
and a digital signal processing unit.
• Traversing the Seafloor ,searches for an
object.
• When object found sends an acoustic
signal to a ship or shore based station.
• Can then be commanded to take a still
frame photo,compress it and transfer the
image to an acoustic signal that is sent back
to the investigator
8
Robot Crawler

9. Simulation Results
9

10. Analog testing
10
(a) Transmitter on dock (b) Receiver on boat

11. Conclusion
• The potential benefits of the adaptive modem and a general
digital hardware platform architecture has been described.
• The results show that rate adaptation can lead to substantial
energy savings while ensuring reliable communication.
11

12. References
• Lingjuan Wu, Jennifer Trezzo, Diba Mirza, Paul Roberts, Jules Jaffe,
Yangyuan Wang, Fellow, IEEE, and Ryan Kastner, Member, IEEE
“Designing an Adaptive Acoustic Modem for Underwater Sensor
Networks”. IEEE Transactions On Embedded System, vol. 4, no. 1, March
2014.
• Mohsin Murad, Adil A. Sheikh, Muhammad Asif Manzoor, Emad
Felemban, and Saad Qaisar, “A Survey on Current Underwater Acoustic
Sensor Network Applications” International Journal of Computer Theory
and Engineering, Vol. 7, No. 1, February 2015
• F. Akyildiz, D. Pompili, and T. Melodia, “Challenges for efficient
communication in underwater acoustic sensor networks,” ACM Sigbed
Rev., vol. 1, no. 2, pp. 3–8, Jul. 2004.
12

13. 13

14. 14
Thank You