14-10-2010, 11:58 AM
LED WIRELESS.pptx (Size: 1.66 MB / Downloads: 151)
This article is presented by:MALAY RANJAN SAHU
[0711015024]
AE & I
LED WIRELESS
AlGaAs & AlGaInP are used in led to produce high brightness light.Recently developed AlInGaP materials have to produce bluish-green LEDs,has luminous efficacy peaks much higher than those for incandescent lamps …
The novel idea of this article is to modulate light waves emitted from visible LEDs & encoded with audio information for transmitting & broadcasting audio &digital information.
I LIGHT
This concurrent use of visible LEDs for simultaneous
signaling and communication, called iLight, leads to many new and interesting applications and is based on the idea of fast switching of LEDs and the modulation visible-light waves for free-space communications..
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 signal can be received in open air over a distance of 59.3 m
or 194.5 ft.
LOS(LINE OF SIGHT)
All products with visible-LED components can be turned into an information beacon.
The iLight transceivers make use of the direct line-of-sight (LOS) property of visible light, which is ideal in
applications for providing directional guidance to persons with visual impairments.
iLight is that the transmitter provides easy targets for LOS reception by the receiver. This is because the LEDs being on at all times, are also indicators of the location of the transmitter.
A user searching for information has only to look for lights from an iLight transmitter..
there is no need to implement an additional transmitter for information broadcasting.
The locations of the audio signal broadcasting system
and the receiver are relatively stationary. Since the relative speed between the receiver and the source are much less than the speed of light, the Doppler frequency shift observed by the receiver can be safely neglected.