PULSE WIDTH MODULATION &DEMODULATION

Guide Presented by

Mr.M Cheenya V.Abhinav Kumar 11E31A0422

Asst.Professor K.Shiva Kumar 11E31A0423

K.Rajashekhar 11E31A0424

K.Chaithanya Sree 11E31A0428

K.Pramitha 11E31A0429

INTRODUCTION Modulation:

Modulation can be defined as the process of varying a

parameter of carrier signal in accordance with the

instantaneous value of the message signal.

Modulation is used to reduce the size of the antenna and

increases efficiency.

Types of modulation techniques

1. PAM--Pulse Amplitude Modulation

2. PWM—Pulse Width Modulation

3. PPM—Pulse Position Modulation

What is PWM…? Pulse width modulation is a technique that generates

variable width signal generally based on modulator signal

information.

The general purpose of PWM is to control power delivery.

Block Diagram of PWM

Power supply

Transformer It is a device used to increment or decrement the input

voltage as per the requirement.

In this we used step down transformer to convert 230V

AC to 12V AC.

Rectifier A circuit which is used to convert A.C to D.C is known as

rectifier.

Voltage Regulator Here we used LM-7812 Voltage regulator.

It is used to supply a stable voltage.

LED LED is a two lead semiconductor light source.

It resembles a basic pn-junction diode, which emits light

when active.

Representation of LED

Pulse width modulation

PWM is a modulation technique, which converts an

analog signal into a digital signal for transmission.

PWM converts an audio signal into a sequence of pulses

having constant amplitude, but the width is proportional to

amplitude of an audio signal.

Circuit diagram

555 Timer

Features of IC 555

Maximum operating voltage 16V.

Operates in the temperature range of -55 to 125 degrees.

Maximum output current 200mA.

8-pin metal can.

Applications of 555 timer

Ramp and Square wave generator.

Frequency dividers.

Voltage controlled oscillators.

Pulse generators .

Output waveform of Modulation

Demodulation Demodulation is the act of extracting the original

information bearing signal from a modulated carrier wave.

It is used to recover the information content from the

modulated carrier wave.

Pulse width demodulation

Working of demodulation The regenerated PWM is then applied to the ramp

generator & synchronization generator.

The ramp generator produces ramps for the duration of

pulses such that height of ramps are proportional to the

width of ramp pulses.

Synchronous pulse generator produces references pulses

with constant amplitude and pulse width.

Output waveforms of demodulation

Results Input waveform

Output waveform

Advantages Low Noise

Low power consumption

High efficient

Does not require synchronization between transmitter and receiver.

Applications

Telecommunications

Voltage regulation

Power delivery

Amplification

Use as ADC

Conclusion The design of a compact circuit board with good track

routing requires experience in PCB design.

With the help of protel software the kit is developed and

can be used as an experimental kit, it provides user

friendly environment for the users.

THANK YOU