Download - Raviranjan Kumar Singh Semminar Reprasention
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WELCOME
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SEMINAR REPORT
ON
LED - WIRELESS
SUBMITTED BY:-
RAVIRANJAN KU. SINGH
07012310978TH SEM
ECE
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INTRODUCTION
IN RECENT WORD THE NEW DEVLOPMENT INCOMMUNICATION WORLD THROUGH LED IS CALLED I-
LIGHT.
THIS LED TECNOLOGY IN COMMUNICATION IS
USED BECAUSE OF HIGH LUMINOUS EFFICANCY OF
LED DEVICE(LIKE AL-IN-GA-P),FAST SWITCHING AND
MODULATION VISIBLE LIGHT WAVE FOR FERR SPACE
COMMUNICATION.
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IN PLACEWEAREALSO USING THEIR(INFRARED RADIATION) BUTLED
COMMUNICATION HASSOMEADVANTANGE:-
LED
---------------------------------------------------------------1)THE I-LIGHT TRANSCEIVERS MAKE USE
OF THE DIRECT LINE OF SIGHT(LOS)
PROPERTY OF VISIBLE LIGHT, WHICH IS
IDEAL IN APPLICATION FOR PROVIDING
DIRECTIONAL GUIDENCE TO VISUAL
IMPAIRMENTS.
2)I-LIGHT IS EASY TO TARGETS FOR LOS
RECEPTION BY THE RECEIVER.
3)A USER SEARCHING FOR INFORMATION
HAS ONLY TO LOOK FOR LIGHT FROM AN I-
LIGHT TRASMITTER.
4)LED DEVICE IS CONCURRENTELY USE
FOR ILLUMINATION,DISPLAY OR VISUAL
SIGNAGE,FOR THIS NO NEED TO
IMPLEMENT TRANSMITTER FOR
INFORMATION BROADCASTING.
IR
----------------------------------------------------------
1)IR HAS THE PROPERTY OF
BOUNCING BACK AND FORTH
IN A CONFINED ENVIOOMENT.
2)THER IS SO MUCH
DIFFICULTIES TARGET BYRECEIVER.
3)DIFFICULTI TO FIND THE
DIRECTION OF SIGNAL BY
THE USER.
4)EXTRA DEVICE IS USINGFOR TRANSMITTER FOR
INFORMATION
BROADCASTING.
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COMPARISON TABLE
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SYSTEM DESCRIPTIONB THROUGH LED
COMMUNICATION
TRANSMITTER
RECIVER
TRANSMITTER :-
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RECIEVER:-
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PHOTODETECTOR
The photo detector circuit consists of a
photo diode and a resistor. One end of the
photo diode is coupled to the current limiting
resistor with the other end coupled to the
ground . The photo-detector is used to detecta light signal from the transmitter and
convert it into an electrical signal. The
limiting pre-amplifier is used to amplify the
electrical signal from the photo-detector for
the next stage. And it produce rectangular
signal pulses .
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DATA REPRODUCING CIRCUIT
The data reproducing circuit, which consists of anoperational amplifier, a resistor, and two NAND Schmitt
triggers is used.
Its function is to produce rectangular pulses from the
amplified signal in the previous stage.
An operational amplifier is used as a comparator,
which uses a virtual ground as a reference.
The NAND Schmitt trigger gates are used to enhance
the noise immunity and to correct the edges from low tohigh voltage levels due to slew rate of the amplifier.
Two NAND Schmitt trigger gates are used instead of
one so that the signal will not be inverted.
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DIFFERENTIATOR
Then, a differentiator circuit consistingof a capacitor and a resistor is used to
detect the leading edges of the pulse
with the trailing edge blocked by the
diode.
A Schmitt trigger gate is used as a
pulse generator, and the output gives the
inverted version of pulses from thedifferentiator.
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INTEGRATORANDENVELOPEDETECTOR
According to inverted pulse of differentiator ,it get
modulated signal would be reconstructed.
BAND PASS FILTER
The band pass filter is use to filter out high frequency
distortion and low frequency noise . And output from the
band pass filter is an audio signal.
POWERAMPLIFIER
It is use for the delivery of the audible messages
through a speaker or headphone.
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DIGITALDATA TRASMITTER THROUGH LED
A receiver, which resembles a portable traveler
location system, has been implemented to obtain the
demodulated signal.
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TRAFFIC INFORMATION SYSTEM
Vehicle Information & Communication System (VICS)is starting to become practicable .The Infrared
System of VICS detects vehicles on the road by using
optical beacons to control traffic and to supply real
time traffic information. But it is an enormous budget
because the optical beacon must be located on every
lane of the road throughout the country.
Under this background, the utilization of LED traffic
light to transmit information has been patented. This
is because LED traffic light use low power, have better
efficiency and have much longer lamp life. The
proposed setup of this system is shown in fig in whichtraffic light is the transmitter and receiver is fixed in
front of the vehicle
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IMPLEMENTATION & EXPERIMENTALRESULTSThe specification of led traffic signal head are given below :-
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BITERROR RATEEXPERIMENT
A bit error rate (BER) experiment for the LED traffic light has been
performed . In the experiment, frames of data were transmitted
continuously from a computer to the serial communication interface
circuit via the printer port of the computer. The modulated signal is
transmitted by the LED traffic light. The visible-light signal wastransmitted to the receiver, and the serial communication interface
performs demodulation of the data. The computer at the receiver
side would compare the received data with transmitted data. The
number of error bits would be recorded. BER is inversely proposal to
brightness
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APPLICATION OFVISIBLELEDSYSTEM
1) High-brightness LEDs are increasingly being used intraffic lights due to their low power consumption and
minimal required maintenance, which can be translated
into considerable cost savings each year. . LED power
consumption is only 8-12W, compared with around 150W
used by its incandescent counter part.
2) an LED traffic light can be used as an audio
broadcasting device, in addition to their normal function
of being an indication and signaling device.
3) museum or exhibit-hall environment. The information onan individual exhibit can be broadcast via a plurality of
LEDs, which is also used for the purpose of illumination.
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ADVANTAGESOFLEDSYSTEM
Like microwaves, visible-LED light beams follow astraight-line path and are well suited for the wireless
delivery of large quantities of voice and data information.
DISADVANTAGESOFLEDSYSTEM
1) They are suitable for short range.
2) the photo-detector current is proportional to the
received power.
3) that the relationship between the radiant intensity and
the distance from the receiver follows the inverse
square law.4) It is not suitable for broadcasting signals over a wide
coverage area or over long ranges. Because noise
arising from sunlight, incandescent lighting, and
fluorescent lighting.
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High brightness LEDs are getting more popular and are
opening up a number of new applications, especially with
the improved efficiency and new colors. 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.
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. Thereare 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
CONCLUSION
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THANK-
YOU