High Rate Acoustic Link for Video Transmission from Autonomous Underwater Vehicles (AUVs)

PI: Milica Stojanovic, MIT Sea Grant, Lee Freitag, Woods Hole Oceanographic Institute

Project Number:2002-RD-17

Start Date:2002-03-01End Date:2004-02-28

Proposal Summary

Objectives: The objective of the proposed work is to demonstrate the capability to transmit near real-time video signals from an autonomous underwater vehicle (AUV) to a surface platform. Acoustic communication techniques are to be used for transmission over a vertical path at depths between several tens and several hundreds of meters.

Towards achieving the main objective, we propose to:
1. identify video compression techniques that minimize the bit rate required for signal transmission
2. design highly bandwidth efficient modulation and detection methods that maximize the information throughput over a band limited acoustic channel (>3b/s/Hz)
3. design detection methods for high level signal constellations in the presence of acoustic channel distortion
4. implement the designed algorithms in software
5. demonstrate the methods proposed using at sea experimental transmissions over vertical path channels

Methodology: The methodology that we will use is based on a three step sequence that progresses from theoretical to experimental work:

Step one. Theoretical work.
-assessment of existing technology
-conceptual design of signals and signal process algorithms (reference is to low bit rate video compression; high level modulation methods with variable constellation shapes, and detection in the presence of phase and timing jitter)

Step two. Implementation and testing.
-software implementation of algorithms in Matlab
-design verification and performance testing

Step three. Experimental work.
-signal design for experiments
-experiments at sea to collect real data
-data analysis

Experimental work will be performed in collaboration with the Woods Hole Oceanographic Institution using their acoustic modem and AUV experiments of opportunity.

Rationale: The problem of video transmission from an AUV represents one of the last milestones in the development of autonomous ocean sampling and monitoring systems. The results of this work will be beneficial to any tetherless systems that require high rate data transmissions. Specifically, the MIT AUV lab expressed interest in implementing the AUV video link. Finally, the project presents a very interesting research challenge, while the opportunity to work with WHOI provides excellent chances of success.



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