27-04-2011, 03:08 PM
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RAVIRANJAN KU. SINGH
RAVIRANJAN KUMAR SINGH SEMMINAR REPRASENTION.pptx (Size: 840.11 KB / Downloads: 68)
INTRODUCTION
IN RECENT WORD THE NEW DEVLOPMENT IN COMMUNICATION 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.
PHOTO DETECTOR
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 detect a 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
DATA REPRODUCING CIRCUIT
The data reproducing circuit, which consists of an operational 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 to high 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.
DIFFERENTIATOR
Then, a differentiator circuit consisting of 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 the differentiator.
INTEGRATOR AND ENVELOPE DETECTOR
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.
POWER AMPLIFIER
It is use for the delivery of the audible messages through a speaker or headphone.
DIGITAL DATA TRASMITTER THROUGH LED
A receiver, which resembles a portable traveler location system, has been implemented to obtain the demodulated signal.
RAVIRANJAN KU. SINGH
RAVIRANJAN KUMAR SINGH SEMMINAR REPRASENTION.pptx (Size: 840.11 KB / Downloads: 68)
INTRODUCTION
IN RECENT WORD THE NEW DEVLOPMENT IN COMMUNICATION 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.
PHOTO DETECTOR
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 detect a 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
DATA REPRODUCING CIRCUIT
The data reproducing circuit, which consists of an operational 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 to high 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.
DIFFERENTIATOR
Then, a differentiator circuit consisting of 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 the differentiator.
INTEGRATOR AND ENVELOPE DETECTOR
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.
POWER AMPLIFIER
It is use for the delivery of the audible messages through a speaker or headphone.
DIGITAL DATA TRASMITTER THROUGH LED
A receiver, which resembles a portable traveler location system, has been implemented to obtain the demodulated signal.