Audio Transmission Through Visible Light Communication System : Design Considerations and Performance Evaluations Mariyam Thomas Department of E.C.E Amal Jyothi College of Engineering Kanjirappally, Kottayam, Kerala Binu Mathew Department of E.C.E Amal Jyothi College of Engineering Kanjirappally, Kottayam, Kerala Abstract— As the radio spectrum is already crowded, there is a need for new medium for faster and more secure wireless communication. To address this problem, a new communication technology called Visible Light Communication (VLC) is introduced. VLC system to transmit an audio signal is presented in this paper. Performance of visible light communication system is tested and analyzed. Besides that, influence of additional amplifier at the receiver on the system is characterized. Results show that the performance of the system is increased by adding the amplifier circuit. Also, the distance between transmitter and receiver can influence the system performance. For longer distances, performance is poor and loss is more. As a conclusion, a visible light communication system for audio transmission is demonstrated and a maximum range of 50 cm is achieved for this system. Keywords—Radio Spectrum; Wireless Communcation; Visible Light Communication; Amplifier I. INTRODUCTION Communication has a vital role in the field of electronics and communication. It deals with transfer of data from one place to another. Transmission can be done by wired or wireless medium. Current trend of wireless communication demands higher throughput and ubiquitous coverage, which sets high demand for spectrum utilization of the radio frequency communication. This ever increasing demands will leads a growth in mobile data traffic at a compound annual growth rate (CAGR) of 61 percent from 2013 to 2018 [1]. Visible Light Communication (VLC) has been proposed as an alternative means of wireless transmission. Visible light provides about 400 THz unlicensed, unregulated, safe and radio free media for wireless communications. The bandwidth of visible light is over 1000 times wider than all other radio frequencies and together which allows enormous capacity for communication purposes. Fig. 1 shows the location of visible light spectrum in electromagnetic spectrum. It can be seen that wavelengths between 380 nm to 780 nm is used for visible light communication system. With the development and utilization of Light Emitting Diode (LED) technology, interest of visible light communication has been increased. LED can provide high energy efficient and bandwidth efficient system for communication purposes. Fig. 1. Visible light as a part of electromagnetic spectrum The basic idea of VLC system is to add information into the light source and at the receiver side, the light intensity changes detected using a photo detector. This is called intensity modulated communication and the modulation frequency used is much higher than that the human eye can detect and so, the flickering can be avoided. Since the light can not penetrate through the opaque objects, VLC is a directed communication medium. The combination of lighting and communication infrastructure will be cost efficient and consumes less energy. Before the evolution of LED, sunlight or fire or other lamps were used for the transmission of information. For example, they were used in beacon fires and lighthouses. Development of LED has enhanced the bandwidth and intensity modulation in VLC system. First LED based VLC system was made in 2001 by RONJA project [2]. A long range optical bidirectional link was developed by this system and achieved a 1.4 km link at a data rate of 10Mbps using red light. VLC has several advantages over traditional radio frequency and infrared communication. The main advantage of VLC is the 400 THz unlimited, unlicensed and safe band for communication. The whole RF band is 300GHz wide and which is strictly limited and regulated. Another advantage of VLC is low power consumption and low cost. VLC uses low cost illumination lamps for communication while RF communication requires its own base station and more energy. The main difference is, RF can propagate through obstacles. While the VLC and IR can provide high security data transmission over the required area. So, the coverage and International Journal of Engineering Research & Technology (IJERT) ISSN: 2278-0181 http://www.ijert.org IJERTV5IS080427 Vol. 5 Issue 08, August-2016 (This work is licensed under a Creative Commons Attribution 4.0 International License.) Published by : www.ijert.org 587