Underwater Optical Communication Semester Project López Estepa, Pedro Assistant: Konstantinos Karakasiliotis Professor: Auke Jan Ijspeert Final presentation 13 January 2009

Underwater Optical Communication - Pedro López Estepa Summary Goals Initial Problems Wireless Communication Technologies Designed System Experiments Conclusions Future work Only general Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Goals Project Description Radio Blue light [receiver] [transmitter] video and data accompanying vehicle control Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Goals Goals of the Project Develop a communication system to transmit video between underwater robot and surface platform Decrease size due to space restrictions. Find a good combination of communication speed and robustness. Underwater Optical Communication - Pedro López Estepa

Initial Problem Initial Problem Most of the current underwater optical communication systems can be clasified in two groups in terms of their limitations. Size Limitations Power Limitations We are not included in only one of them! Optical Communication System Size Limitations Power Limitations Underwater Optical Communication - Pedro López Estepa

Wireless Communication Technologies 31.09.2008 – 16.10.2008 High frequency radio wave is highly absorbed in water. Acoustic communication systems are relatively low bandwidth. Optical communication with LASER is monidirectional. Optical communication in Visible Spectrum Omnidirectional Bandwidth up to some MHz Minimal light absorption in water is usually achieved for blue light around 400-450 nm. Felix Schill , Uwe R. Zimmer , and Jochen Trupf. “Visible Spectrum Optical Communication and Distance Sensing For Uncerwater Applications”. The Australian National University, ACT 0200. Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Designed System 16.10.2008 – 20.12.2008 System Designed 16.10.2008 – 20.12.2008 TX Water RX Video signal Modulation XOR LED Driver LED CLK Vdd GND Lens As big as we need the receive platform Demodulated signal Vdd Demodulation Filtering Amplification Photodiode GND Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Designed System 16.10.2008 – 20.12.2008 Transmitter LED Driver Modulation XOR Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Designed System 16.10.2008 – 20.12.2008 Transmitter Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Designed System 16.10.2008 – 20.12.2008 Transmitter LUXEON III Blue 700 mA - 3W Underwater Optical Communication - Pedro López Estepa

Designed System 16.10.2008 – 20.12.2008 Receiver Signal Treatment Amplification The video will be already processed in the FPGA so it will be easy to extract the XOR of the signal and give it as an input to the TX Filtering Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Designed System 16.10.2008 – 20.12.2008 Receiver Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Experiments 20.12.2008-09.12.2009 Air experiments Signal is clear in 0,5 we can amplifier Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Experiments 20.12.2008-09.12.2009 Air experiments Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Experiments 20.12.2008-09.12.2009 Underwater experiments-Hardware Setup Depth 10 cm Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Experiments 20.12.2008-09.12.2009 Underwater experiments Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Experiments 20.12.2008-09.12.2009 Underwater experiments Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Experiments 20.12.2008-09.12.2009 Underwater experiments Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Conclusions The experiments have shown that the range is not decreased while working in underwater The wide angular coverage of 30º, due to the used lens, doesn’t allow more than 10 cm range around the perpendicular point of movement To obtain omnidirectional coverage it’s necessary to include an improved lens system in the receiver with several photo diodes to increase the detection range Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Conclusions It’s necessary to try to decrease the power consumption after the lenses analysis is finished. The experiments show that the system has a good response in the range of 500 kHz to 1.50 MHz, which could be increased to 2 MHz by using a better lens system. According to the initial project requirements We have completed the electronic hardware fabrication, which means, design and build the physical layer for an underwater communication system. Even if we didn’t manage to get the transmitter underwater, the setup we used resembles in a good way the final one. A systematic analysis to determine the most efficient lenses system is not completed. Underwater Optical Communication - Pedro López Estepa

Time Frame Time Completed task Actual task W. Communication technologies Communication type selection Preliminary experiments Fast optical communications Trasmitter design Transmitter build Receiver design Receiver build Air experiments Underwater experiments Improvements Time Completed task Actual task Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Future work Improvements Analyze and improve lenses system High Frequency amplification in receiver PCB Reduce Build platform Enchance harware for underwater emplacenment Implement Software demodulation … Underwater Optical Communication - Pedro López Estepa

Underwater Optical Communication - Pedro López Estepa Questions Underwater Optical Communication - Pedro López Estepa