429253300429253300429253300429253300-lifi.docx
- 1. LI-FI(LIGHT FIDELITY) BASED HIGH DATA RATE VISIBLE LIGHT COMMUNICATION FOR DATA AND AUDIO TRANSMISSION ABSTRACT Li-Fi stands for Light-Fidelity. The technology is very new and was proposed by the German physicist Harald Haas in 2011. Li-Fi provides transmission of data through illumination by sending data through a LED light bulb that varies in intensity faster than human eye can follow. In this , we will discuss the technology in detail and also how Wi-Fi can be replaced by Li-Fi. Wi-Fi is useful for general wireless coverage within buildings while Li-Fi is ideal for high density wireless data coverage in confined areas where there are no obstacles. Li-Fi is a wireless optical networking technology that uses light emitting diodes (LEDs) for transmission of data. The term Li-Fi refers to visible light communication (VLC) technology that uses as medium to deliver high-speed communication in a manner similar to Wi-Fi. Li-Fi provides better bandwidth, efficiency, availability and security than Wi-Fi and has already achieved high speeds in the lab. Li-Fi is a data transfer technique that uses light. Light is analogous not only to illumination but also to speed. Li-Fi is also much secured since light cannot pass through walls. It uses visible light portion of the electromagnetic spectrum to transmit information. Hence the visible light communication solves the problem of radio frequency congestion. In this project we transmit data and audio through light at very high data rates without use of microcontrollers and its other peripheral devices.
- 2. INTRODUCTION Li-Fi, a short form for Light Fidelity, is a wireless technology that makes use of visible light communication instead of radio waves. In this, common household LED bulbs can be utilised to allow data transfer with a speed of up to 224 gigabits per second, which equates to downloading around 18 movies each of 1.5 GB in every single second. This term was coined by Professor Harald Haas during a TED TALK in the year 2011. Basically, with this technology, people will be able to use light bulbs and solar cells as wireless routers for transmitting data. He even set up a company named pure LiFi in 2012 and aims to be the world leader in Visible Light Communications technology. A simple LiFi circuit is presented here for school and college final year projects showing how to transmit music through LED light across a given distance, using only LED light without creating any fluctuations in the LED and yet transferring the light with perfection. Light Fidelity (Li-Fi) is a bidirectional, high-speed and fully networked wireless communication technology similar to Wi-Fi. Li-Fi is the term some have used to label the fast and cheap wireless communication system, which is the optical version of Wi-Fi. Li-Fi uses visible light instead of Gigahertz radio waves for data transfer. LI FI (light fidelity) is data through illumination-taking he fiber out of fiber optics by sending data through an LED light bulb that varies in intensity faster than the human eye can notice. At the heart of this technology is a new generation of high brightness LEDs. If the LED is on a digital 1 is transmitted, if the LED is off then a digital 0 is transmitted. They can be switched on and off in order to transmit data continuously.
- 3. CIRCUIT DIAGRAM COMPONENT 1. light-emitting diode (LED):- LED is a semiconductor light source that emits light when current flows through it. When a current flows through the diode, electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence.
- 4. The colour of the light (corresponding to the energy of the photons) is determined by the energy band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device. Parts of a conventional LED. The flat bottom surfaces of the anvil and post embedded inside the epoxy act as anchors, to prevent the conductors from being forcefully pulled out via mechanical strain or vibration. Figure : Led 2.Solar :- Solar-powered photovoltaic (PV) panels convert the sun's rays into electricity by exciting electrons in silicon cells using the photons of light from the sun. This electricity can then be used to supply renewable energy to your home or business. Solar cells can be used to generate electricity from sunlight. It is a device that converts light energy into electrical energy. Sometimes the term solar cell is reserved for devices intended specifically to capture energy from sunlight, while the term photovoltaic cell is used when the light source is unspecified.
- 5. Figure : Solar Plate 3.Speaker:- An audio amplifier is an electronic device that increases the strength (amplitude) of audio signals that pass through it. An audio amplifier amplifies low- power audio signals to a level which is suitable for driving loudspeakers.
- 6. Figure :- Speaker 4. Capacitor:-A capacitor can store electric energy when it is connected to its charging circuit. And when it is disconnected from its charging circuit, it can dissipate that stored energy, so it can be used like a temporary battery. Capacitors are commonly used in electronic devices to maintain power supply while batteries are being changed. Figure :- Capacitor 5. 3.5MM Jack Cable:- An audio signal is a representation of sound, typically as an electrical voltage for analog signals and a binary number for digital signals. Audio signals have frequencies in the audio frequency range of roughly 20 to 20,000 Hz (the limits of human hearing). Figure :- 3.5mm Jack
- 7. 6.Resistor:- it is an electrical device may be a passive two-terminal electrical part that implements resistance as a circuit component. In electronic circuits, resistors unit of measurement accustomed reduce current flow, alter signal levels, to divide voltages, bias active components, and terminate transmission lines, among completely different uses. Figure :- Resistor 7. Battery :- An electric battery is a device consisting of one or more electrochemical cells with external connections provided to power electrical devices such as flashlights, and electric cars. When a battery is supplying electric power, its positive terminal is the cathode and its negative terminal is the anode. The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal. When a battery is connected to an external electric load.
- 8. Figure :- Battery 8. Wire:- A length of such material, consisting either of a single filament or of several filaments woven or twisted together and usually insulated with a dielectric material, used as a conductor of electricity. Figure:- Wire
- 9. MUSIC CIRCUIT This project is about making a 5 Watt stereo audio amplifier using the UTC TEA2025 IC chip. Figure :- Music Circuit
- 10. Figure :- IC Diagram TEUTC TEA2025 is a monolithic integrated audio amplifier IC in a 16-pin plastic dual in line package. It is originally designed for portable cassette players and radios, but it can be used to make a pretty decent stereo audio amplifier for an ipod or mp3 player. It requires very few external components and can run on as low as 3 V power supply. The pin diagram of TEA2025 and the application circuit for stereo application are shown below.
- 11. An interesting characteristic of TEA2025 is it has built-in thermal protection circuit. If you want to run it at its full capacity (5 W), you should provide a heat sink in the circuit. In case you don’t, the internal thermal protection won’t let the device damage; all that happens is that the output power is reduced when an excessive junction temperature is sensed. At the input stage, a logarithmic dual taper potentiometer (10 or 20 K) can be used to provide the volume control feature. The 0.22 µF capacitors at the input side help to minimize any noise due to variable resistor contact. The 0.15 µF capacitors at the output end are for frequency stability. Use of other value capacitors could result in unwanted oscillations at the output. Long wire connections and ground loops in the circuit could also cause oscillations, so a good layout of the circuit PCB is very important. I built this circuit on a 5 cm x 9 cm general purpose prototyping circuit board as shown below. The circuit is put inside a 6 cm x 11 cm size plastic enclosure and necessary connections (power supply, speaker, and stereo input terminals) are drawn out of the box. The circuit can be powered from 3-12 V power supply. I am powering this with my spare 9.6V rechargeable battery from my broken RC toy. I am happy with the performance of TEA2025 as an stereo audio amplifier.
- 12. COMPONENT USING MUSIC CIRCUIT 1. Capacitor:- capacitor is a little like a battery. Although they work in completely different ways, capacitors and batteries both store electrical energy. If you have read How Batteries Work, then you know that a battery has two terminals. Inside the battery, chemical reactions produce electrons on one terminal and absorb electrons on the other terminal. A capacitor is much simpler than a battery, as it can't produce new electrons -- it only stores them. Inside the capacitor, the terminals connect to two metal plates separated by a non-conducting substance, or dielectric. You can easily make a capacitor from two pieces of aluminium foil and a piece of paper. It won't be a particularly good capacitor in terms of its storage capacity, but it will work. Figure :-Capacitor 2. TEA2025 IC:- The UTC TEA2025 is a monolithic integrated audio amplifier IC in a 16-pin plastic dual in line package. It is originally designed for portable cassette players and radios, but it can be used to make a pretty decent stereo audio amplifier for an iPod or mp3 player. It requires very few external components and can run on as low as 3 V power supply. The pin diagram of TEA2025 and the application circuit for stereo application are shown below.
- 13. Figure :- IC Diagram 3. Speaker:- A speaker is a term used to describe the user who is giving vocal commands to a software program. Speakers are made up of a cone, an iron coil, a magnet, and housing (case). When the speaker receives electrical input from a device, it sends the current through the causing it to move back and forth. This motion then vibrates the outer cone, generating sound waves picked up by our ears. Figure :- speaker
- 14. 3. Resistance:- The resistor is a passive electrical component to create resistance in the flow of electric current. In almost all electrical networks and electronic circuits they can be found. The resistance is measured in ohms. An ohm is the resistance that occurs when a current of one ampere passes through a resistor with a one volt drop across its terminals. The current is proportional to the voltage across the terminal ends. This ratio is represented by Ohm’s law: Resistors are used for many purposes. A few examples include delimit electric current, voltage division, heat generation, matching and loading circuits, control gain, and fix time constants. They are commercially available with resistance values over a range of more than nine orders of magnitude. They can be used to as electric brakes to dissipate kinetic energy from trains, or be smaller than a square millimetre for electronics Figure :- Resistor
- 15. WORKING Li-Fi and Wi-Fi are quite similar as both transmit data electromagnetically. However, Wi-Fi uses radio waves, while Li-Fi runs on visible light waves. As we now know, Li-Fi is a Visible Light Communications (VLC) system. This means that it accommodates a photo-detector to receive light signals and a signal processing element to convert the data into 'stream able' content. An LED light bulb is a semiconductor light source meaning that the constant current of electricity supplied to an LED light bulb can be dipped and dimmed, up and down at extremely high speeds, without being visible to the human eye. For example, data is fed into an LED light bulb (with signal processing technology), it then sends data (embedded in its beam) at rapid speeds to the photo-detector (photodiode). The tiny change in the rapid dimming of LED bulbs is then converted by the 'receiver' into electrical signal. The signal is then converted back into a binary data stream that we would recognize as web, video and audio applications that run on internet-enabled devices. Figure: Block diagram
- 16. EFFICIENCY:- The current system is high on energy consumption. For every unit of energy consumed the data transmitted is relatively less. The data speeds in the current system can only reach up to a few hundreds of megabits per second. BENEFITS:- Security:- In contrast to radio frequency waves used by Wi-Fi, lights cannot penetrate through walls and doors. This makes it more secure and makes it easier to control access to a network As long as transparent materials like windows are covered, access to a Li-Fi channel is limited to devices inside the room. Underwater application:- Most remotely operated underwater vehicles (ROVs) are controlled by wired connections. The length of their cabling places a hard limit on their operational range, and other potential factors such as the cable's weight and fragility may be restrictive. Since light can travel through water, Li-Fi based communications could offer much greater mobility. Li-Fi's utility is limited by the distance light can penetrate water. Significant amounts of light do not penetrate further than 200 meters. Past 1000 meters, no light penetrates. Hospital:- Many treatments now involve multiple individuals, Li-Fi systems could be a better system to transmit communication about the information of patients. Besides providing a higher speed, light waves also have little effect on medical instruments and human bodies.
- 17. Vehicles:- Vehicles could communicate with one another via front and back lights to increase road safety. Street lights and traffic signals could also provide information about current road situations. Industrial automation:- Anywhere in industrial areas data has to be transmitted, Li-Fi is capable of replacing slip rings, sliding contacts and short cables, such as Industrial Ethernet. Due to the real time capability of Li-Fi (which is often required for automation processes) it is also an alternative to common industrial Wireless LAN standards. Speed:- Li-Fi can possibly deliver data transfer speeds of 224 gigabits per second which clearly leaves Wi-Fi far behind. As per the tests conducted by pure LiFi, the technology produced over 100 Gbps in a controlled environment. Moreover, the visible light spectrum is 1,000 times larger than the 300 GHz of RF spectrum which helps in gaining high speed. Energy Efficiency:- Usually, Wi-Fi needs two radios to communicate back and forth which takes a lot of energy to discern the signal from the noise as there may be several devices using the same frequency. Each device has an RF transmitter and baseband chip for enabling communication. However, as Li-Fi uses LED lights, the transmission requires minimal additional power for enabling communication. Data Density:- Owing to the interference issues, Wi-Fi works in a less dense environment while Li-Fi works in a highly dense environment. The area covered by one Wi-Fi access point has 10s or 100s of lights and each LiFi light can deliver the same speed or greater than a Wi-Fi access point. Therefore, in the same area, LiFi can provide 10, or 100, or 1000 times greater wireless capacity.
- 18. CONCLUSION:- The concept of Li-Fi is currently attracting a great deal of interest, not least because it may offer a genuine and efficient alternative to radio based wireless. As a growing number of people and their devices access wireless internet, the air waves are becoming increasingly clogged, making it more and more difficult to get a reliable, high-speed signal. So Li-Fi has a bright future. LI FI will make are lives more technology driven in the near future. With its magic of light it can make our world a greener, safer, cleaner and more over a brighter place to live.