SOUDA (Transferring Data via Light)

One of the most interesting technologies in the industry today is wireless technology. This statement is not founded on the “latest and greatest” in communications breakthrough. 



All to often we hear how evolving technology will unshackle us from the traditional “pairs of wireless” which provide our present-day communication. Wireless, however, has been around for decades in variations and techniques. Only recently have newer applications breathed life back into mundane services, sparking international interest in the applications, bandwidths and legality of wireless communication. Today everyone is buzzing about the future of the wireless world and our abilities to communicate in general. 

Visible light is the form in which electromagnetic radiation with wavelengths in a particular range is interpreted by the human brain. Visible light is thus by definition comprised of visually-perceivable electromagnetic waves. The visible spectrum covers wavelengths from 380 nm to 750 nm. At the lower end of the spectrum, there are violet-bluish tones and light at the other end of the spectrum is interpreted to be distinctly red. Note that some animals exist whose vision merges into the ultraviolet (< 380 nm) or the infrared (> 750 nm).

the system’s ability to transmit data at the speed of 100 Kbps with the distance of 40cm.In this research, they also discussed reflection and inter symbol interference. This system successfully performed without a battery. This system used the white LED as the transmitter and the photocell as the receiver carried out the numerical simulations for an optimal lights layout scheme for the visible light communication to find the effectiveness of this communication system. There were two kinds of communication systems being proposed, an optical up-link and an optical downlink. The up-link had a small, superficial area and narrow-angle of irradiance like an electric torch whereby the LED could be lighted from the bottom to the top. 

Generally, the down-link system had a large superficial area and wide-angle of irradiance because the light was located at the ceiling and lighted from the top to the bottom. The performance of the visible light communication was analyzed using the optimal lights layout scheme in terms of the received power and bit error rate (BIT). Based on the numerical simulation results, the received power was very large compared to the infrared wireless communication which could make broadband communication possible. The effectiveness of the light layout was analyzed based on the received power.

The idea of Li-Fi was introduced for the first time by a German physicist Harald Hass in the TED (Technology, Entertainment, Design) Global talk on Visible Light Communication (VLC) in July 2011, by referring to it as “data through illumination”. ^[1]

He used a table lamp with an LED bulb to transmit a video of a blooming flower that was then projected onto a screen. In simple terms, Li-Fi can be thought of as a light-based Wi-Fi i.e. instead of radio waves it uses light to transmit data. In place of Wi-Fi modems, Li-Fi would use transceivers fitted with LED lamps that could light a room as well as transmit and receive information. By adding new and unutilized bandwidth of visible light to the currently available radio waves for data transfer, Li- Fi can play a major role in relieving the heavy loads which the current wireless system is facing. Thus, it may offer additional frequency band of the order of 400 THz compared to that available in RF communication which is about 300 GHz. Also, as the Li-Fi uses the visible spectrum, it will help alleviate concerns that the electromagnetic waves coming with Wi-Fi could adversely affect our health.

By Communication through visible light, Li-Fi technology has the possibility to change how we access the Internet, stream videos, receive emails and much more. Security would not be an issue as data can’t be accessed in the absence of light. As a result, it can be used in high-security military areas where RF communication is prone to eaves dropping. The idea of Li-Fi was introduced for the first time by a German physicist Harald Hass in the TED (Technology, Entertainment, Design) Global talk on Visible Light Communication (VLC) in July 2011, by referring to it as “data through illumination”. 

The working of Li-Fi is very simple. There is a light emitter on one end i.e. an LED transmitter, and a photodetector (light sensor) on the other. The data input to the LED transmitter is encoded into the light (technically referred to as Visible Light Communication) by varying the flickering rate at which the LEDs flicker ‘on’ and ‘off’ to generate different strings of 1s and 0s. The on-off activity of the LED transmitter which seems to be invisible (The LED intensity is modulated so rapidly that human eye cannot notice, so the light of the LED appears constant to humans), enables data transmission in light form in accordance with the incoming binary codes: switching ON a LED is a logical '1', switching it OFF is a logical '0'. By varying the rate at which the LEDs flicker on and off, information can be encoded in the light to different combinations of 1s and 0s.^[2]

The submitted system receives a sound signal and power, together that is transmitted as LED emission. Later, that emission is received by the receiver and converted as the sound signal, using only Resistors, Capacitors, Audio Amplifiers, Battery, Photo transmitter, 3.5 Audio plugs, Arduino and Display as shown in figure 1.  

Figure 1: Process of the transmission

In transmitter side, when we connect 3.5mm jack to audio source LED will glow but there is no fluctuation in the intensity of light when the audio source is OFF. As soon as you play the audio, you will see that there is frequent change in intensity of light. When you increase the volume, LED’s intensity is changing faster than the human eye can follow. The solar panel is so sensitive that it can catch small intensity change and correspondingly there is the change in the voltages at the output of the solar panel. So, when the light of LED falls on the panel, voltages will varies according to the intensity of light. 

Then voltages of the solar panel are fed into an amplifier (Speaker) which amplifies the signal and giving the audio output through the speaker connected to the amplifier. The output will come as long as the solar panel is in contact with LED. You can put the LED at max. 15-20cm distance from the solar panel to get the clear audio output. You can further increase the range by increasing the area of solar panel and higher wattage Power LED.

References

VVIET, MYSORE, VOICE AND DATA COMMUNICATION USING Li-Fi, International Journal of Advanced Computational Engineering and Networking, ISSN: 2320-2106, Volume-4, Issue-10, Oct.-2016. 

Renu Kalakoti, Pranita Nehete, A REVIEW ON LI-FI: DATA TRANSMISSION THROUGH ILLUMINATION, International Journal For Technological Research In Engineering Volume 3, Issue 7, March-2016.