International Journal of Modern Trends in Engineering and Research www.ijmter.com e-issn No.:2349-9745, Date: 28-30 April, 2016 Visible light underwater communication using different light sources Pranav Medhekar 1, Sumeet Mungekar 2, Vinayak Marathe 3, Vijay Meharwade 4 1 Department of E&TC, SSJCE, pranav.medhekar19@@gmail.com 2 Department of E&TC, SSJCE, smungekar7@gmail.com 3 Department of E&TC, SSJCE, vinmarathe100@live.com 4 Department of E&TC, SSJCE, vmluffy@gmail.com Abstract We all know that light can be used for communication through air. We extended this technology and use this for underwater communication using different light sources. We use LEDs as a light source because LEDs have longer lifespan, low power consumption, lower heat generation, fast switching characteristics and energy efficient. It can be used for high speed data transfer. We use LASERs as another light source because it is highly directional, travels longer range, Monochromatic, highly coherent and it also has faster switching characteristics. We know that the bandwidth of Radio frequency spectrum is limited. Nowadays the demand for communication has drastically increased and the bandwidth of radio frequency spectrum is limited. Therefore the radio frequency spectrum is depleted. Successful underwater communication is achieved at the speed of 115kbps. Keywords- Laser, VLC, LED, Microcontroller, Photodiode. I. INTRODUCTION The visible light communication (VLC) refers to the communication technology which utilizes the visible light source as a signal transmitter, the air as the transmission medium, and the proper photodiode as a signal receiving component. VLC or Li-Fi (Light Fidelity) is a high speed and fully networked optical wireless communication technology which is similar to Wi-Fi. This term was proposed by Prof. Harald Haas and is a form of visible light communication and a subset of optical wireless communications (OWC). It could be a complement to RF communication (Wi-Fi or Cellular). It is measured to be about 100 times faster than some Wi-Fi implementations, reaching with high speeds. It is wireless and uses visible light spectrum for communication (instead of radio frequency waves), part of optical wireless communications technology, which carries much more information, and has been proposed as a solution to the RF-bandwidth limitations. Li-Fi is advantageous in electromagnetic sensitive areas such as in aircraft cabins, hospitals and nuclear power plants without causing electromagnetic interference. Both Wi-Fi and Li-Fi transmit data using electromagnetic spectrum, but whereas Wi-Fi utilizes radio waves, Li-Fi uses visible light. Li-Fi has almost no limitations on capacity. The visible light spectrum is 10,000 times larger than the whole radio frequency spectrum. Using VLC we can reach data rates of over 10Gbps, which is much faster than typical fast broadband RF networks. In undersea or ocean exploration the data obtained by the sensors or unmanned systems are need to be measured accurately. Thus there is great need for establishing good communication links in seas and oceans. Radio waves do not propagate underwater. Acoustic methods can be used but is limited. Also acoustic waves face difficulty to penetrate the water-air interface. Thus optical communication has high potential to augment other methods. 2.1 Experimental setup II. PROPOSED METHODOLOGY
User will send the data from PC or Laptop, and then it will be passed to the circuitry. The micro controller will drive the light source. The light source is fitted inside the water tank. The source is fully protected from water by proper waterproof coating. We also used Gas and temperature Sensor. Temperature sensor will detect the present temperature at the source. Here we have used two types of light sources. They are LED panel and LASER. LED panel consists of 90 LEDs. We can switch between LEDs and LASER depending upon our requirement. The tank that we have used is of average length such as 1 foot. The tank is filled by water. At the other side the photodiode is also fitted inside the water tank similar to the source. The photodiode is properly aligned with the light source. Photodiode senses the data and it is passed to the microcontroller, and further is obtained on PC or Laptop which is at the other 2.2. Hardware and Software Figure 1. Setup of VLC underwater Microcontroller ATmega 16 is used to convert original signal into data at transmitter and vice versa at the receiver side. It is a CMOS 8-bit microcontroller based on the enhanced RISC architecture. It executes powerful instruction in single clock cycle. The system can be designed optimizing power consumption versus processing speed using AVR ATMega16. Sensor MQ-6 is used as a Gas sensor. It has sensitivity for LPG, iso-butane and propane. It is fast, stable and has long life. Thermistor TTC-103 is used to measure temperature. It is small and operates in the range of -40C to 125C. The microcontroller AVR ATmega16 is programmed using C language. XCTU is used as interfacing software between the circuit and PC/Laptop. XCTU is a free multi-platform application designed to interact with RF modules through a simple graphical interface. XCTU includes all of the tools a developer needs to quickly get up and running with any RF module. XCTU includes a set of embedded tools that can be executed without having any RF module connected. III. WORKING User sends the Data through PC/Laptop. The microcontroller is not compatible with USB port, so we used USB to TTL converter. It converts the data from USB logic to TTL logic, the data from PC gets transmitted to the microcontroller. Thus the file is converted into bits 636
with the help of USB to TTL convertor & ATMEGA-16 Microcontroller. In our project we used two different light sources depending upon our requirement we select the source (either LED or LASER) with the help of switch. Microcontroller forms the driving circuitry of visible light source. The light get intensity modulated which contains the data. Data from PC/Laptop USB to TTL Converter Microcontroller Switch LED LASER Water Data into PC/Laptop TTL to USB Converter Microcontroller Photo detector Figure 2. Block Diagram of Visible Light Underwater Communication In VLC communication the communication is achieved when transmitter and receiver are properly aligned. There is a sensing element at the receiver side called as Photodiode. Photodiode senses the illumination from the light source (either LED or LASER). It converts the optical signal to electrical signal which is passed to microcontroller which is nothing but the regenerated data. Microcontroller identifies the data and route it to the receiver PC through the TTL to USB converter which converts the data from TTL logic to USB logic. Therefore the original data is successfully received at receivers PC. In our project we use two different types of modes viz. 1) PC mode & 2) Sensor Mode. In PC mode, user selects the multimedia file such as image, text, audio or video file. This is fed to the circuitry using interfacing software. Thus the data is transmitted to the receiver. In Sensor mode, the gas sensor senses the LPG, iso-butane gas and thermistor is used to detect the temperature. The sensed data is converted into appropriate units and this data from the sensors (Temperature sensor and Gas Sensor) is transmitted. Thus communication is achieved between to different computers. We can achieve underwater long distance communication underwater using directional high powered visible light sources. IV. CONCLUSION We get accurate underwater communication when the alignment between the transmitter and receiver is achieved properly. Successful underwater communication is achieved at the speed of 115kbps. 637
Light source is switched between LEDs and LASER. Both the type of sources gives accurate communication, however long distance communication is achieved using LASER. When small obstacle blocked the LASER light, so by switching the source to LEDs panel communication is maintained because small obstacle doesn t completely block LED light. Gas and temperature sensor data is successfully measured and is transmitted to the receiver side. REFERENCES [1] Sridhar Rajagopal, Samsung ElectronicsRichard D. Roberts, IntelSang-Kyu Lim, ETRI IEEE 802.15.7Visible Light Communication: Modulation Schemes and Dimming Support Communications Magazine, IEEE, (Vol: 50, Issue: 3) March 2012 ISSN: 0163-6804 [2] WANG Yuanquan and CHI Nan A High-Speed Bi-Directional Visible Light Communication System Based on RGB-LED Communications, China IEEE (Vol: 11, Issue: 3) Page 40 44,March 2014 ISSN: 1673-5447 [3] Yang Aiying ; Li Yankun ; FengLihui Separate Dimming Controlling and Data Transmissionfor an Indoor Visible Light Communication System,Communications, China (Volume:12, Issue: 3 ) Page 71 76 ISSN 1673-5447 Mar. 2015 IEEE [4] Jiaheng Wang ; Rong Zhang ; Hong Shen ; Chunming Zhao ; Hanzo, L. : Multiuser MISO Transceiver Design for IndoorDownlink Visible Light Communication UnderPer-LED Optical Power Constraints,Photonics Journal, IEEE (Volume:7, Issue: 4 ) ISSN :1943-0655 Aug. 2015 [5] Wang Lang ; Chi Xuefen ; Liu Shuangxing ; Shi Wenxiao ; Deng Jing, The Research of Indoor Positioning Based on Visible Light Communication Communications, China (Volume:12, Issue: 8 ) Page(s): 85 92 ISSN :1673-5447 August 2015 [6] XiaotaoFeng ; Pengfei Hu ; Mohapatra, P., Visible Light Communication, Networking andsensing: A Survey, Potential and Challenges Communications Surveys & Tutorials, IEEE (Volume:17, Issue: 4 ) Page(s): 2047 2077 ISSN :1553-877X Fourth quarter 2015 [7] DoKy Son, EunByeol Cho, Inkyu Moon, ZabihGhassemlooy, Soeun Kim and Chung Ghiu Lee, Simultaneous transmission of audio and videosignals using visible light communications EURASIP Journal Wireless Communivcations and Networking, 2013 [8] Amrutha. S, Ansu Mathew, Rajasree. R, SwathySugathan, A Visible Light Communication System for Indoor Application, International Journal of Engineering and Innovative Technology (IJEIT), Volume 3, Issue 12, June 2014 [9] Jacqueline J. George, Mohammed Hayder Mustafa, Nada Mahjoub Osman, NuhaHashim Ahmed, Da ad Mohammed Hamed, A Survey on Visible Light Communication, International Journal Of Engineering And Computer Science, Volume 3 Issue 2, February 2014 Page No. 3805-3808 [10] M..Saadi, Wattisuttikulkij, Y. Zhao, P. Sangwongngam," Visible light communication opportunities, challenges and communication models", International Journal of Electronics and Informatics, Vol. 2, No.1, 2013. 638