23-05-2012, 05:08 PM
LED wireless Technology
LED.ppt (Size: 567 KB / Downloads: 70)
INTRODUCTION:
This advancement as led to the production of large-area full-color outdoors LED displays with divers industrial applications.
The novel idea of this article is to modulate light waves from visible LEDs for communication purposes.
DETECTOR DIODE
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.
Since the signal from the photo-detector circuit is very small, amplification is needed for the next stage.
VOLTAGE CONTROL OSSCILATOR
A voltage-controlled oscillator or VCO is an electronic oscillator designed to be controlled in oscillation frequency by a voltage input
This circuit aims to amplify the input voltage to a certain level, and a comparator is used to produce rectangular signal pulses.
PRE AMPLIFIER CIRCUIT
A preamplifier is an electronic amplifier that prepares a small electrical signal for further amplification or processing.
Two pre-amplifiers are used in this circuit because using one pre-amplifier will require a very high gain amplifier. Hence, two pre-amplifiers, each with lower gain,are used toachieve high gain with reduced noise.
BAND PASS FILTER:
band-pass filter is a device that passes frequencies within a certain range and rejects frequencies outside that range. Optical band-pass filters are of common usage.
A The output signal from the previous stage, integrator and envelope detector has many distortions. A band-pass filter is used to filter out all the high-frequency distortions.
LED.ppt (Size: 567 KB / Downloads: 70)
INTRODUCTION:
This advancement as led to the production of large-area full-color outdoors LED displays with divers industrial applications.
The novel idea of this article is to modulate light waves from visible LEDs for communication purposes.
DETECTOR DIODE
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.
Since the signal from the photo-detector circuit is very small, amplification is needed for the next stage.
VOLTAGE CONTROL OSSCILATOR
A voltage-controlled oscillator or VCO is an electronic oscillator designed to be controlled in oscillation frequency by a voltage input
This circuit aims to amplify the input voltage to a certain level, and a comparator is used to produce rectangular signal pulses.
PRE AMPLIFIER CIRCUIT
A preamplifier is an electronic amplifier that prepares a small electrical signal for further amplification or processing.
Two pre-amplifiers are used in this circuit because using one pre-amplifier will require a very high gain amplifier. Hence, two pre-amplifiers, each with lower gain,are used toachieve high gain with reduced noise.
BAND PASS FILTER:
band-pass filter is a device that passes frequencies within a certain range and rejects frequencies outside that range. Optical band-pass filters are of common usage.
A The output signal from the previous stage, integrator and envelope detector has many distortions. A band-pass filter is used to filter out all the high-frequency distortions.