31-03-2014, 03:01 PM
WIRELESS LED
WIRELESS LED.pptx (Size: 265.39 KB / Downloads: 43)
INTRODUCTION
LED lights are more than an energy-efficient lighting alternative— they’re also a potential Wi-Fi replacement technology.
Researcher at Boston University are working on Smart Lighting, a wireless technology based on visible light instead of radio frequency.
Data is transferred through the Smart Lighting system with LED light, so each light is essentially a Wi-Fi hotspot as shown in figure.
Initial speeds of the network will be about 1 to 10 megabits per second, and data transmission will occur over existing electrical wiring.
LED wireless network are efficient—significantly more so than a radio frequency-based network.
As light doesn’t travel through walls or other opaque objects, chances of eavesdropping are lowered.
BU`s technology is still in the prototype stage, but it could potentially rival radio frequency networks for wireless dominance
System description
TRANSMITTER:
A block diagram representation of the schematic diagram of the transmitter design is shown in figure.
Audio messages can be sent using the LED transmitter, and the receiver located at a distance around 20 m away can play back the messages with the speaker.
The audio amplifier is used to amplify the weak audio signal.
A VCO chip is used to modulate the incoming audio signal variations from the audio amplifier and generate the FM signal.
IMPLEMENTATION :
An LED traffic-signal head made up of 441 high brightness LEDs has been implemented in the Industrial Automation Research Laboratory at The University of Hong Kong.
Each LED is a Hewlett Packard high intensity AlInGaP type with a luminous intensity of 2000 mcd at 20-mA rated driving current, and the viewing angle is 30
APPLICATIONS:
High-brightness LEDs are increasingly being used in traffic lights due to their low power consumption and minimal required maintenance.
The next stage of development will involve the three-color LED signals. In Singapore, there has been a complete change of traffic signals from the incandescent to LED.
An LED traffic light can be used as an audio broadcasting device, in addition to their normal function of being an indication and signalling device.
CONCLUSION
High brightness LEDs are getting more popular and are opening up a number of new applications, especially with the improved efficiency and new colours.
In this article, the novel idea is based on the fast switching of LEDs and the modulation of visible light is developed into a new kind of information system .
A visible-LED audio system that makes use of visual light rays to transmit audio messages to remotely located receiver is described. Such a system made up of high-brightness visible LEDs can provide the function of open space, wireless broadcasting of audio signals. It can be used as an information beacon for short-distance radio communication.
Any illumination device making using of high brightness visible LEDs can be used as a kind of short-range information beacon.. One example is an LED traffic light for the support of roadside-to-vehicle communications. There are many potential novel uses of visible light from LEDs as a communication medium. This concurrent use of LEDs for simultaneous signaling and communications will open up many new applications.