pulse modulation

Lets start the seminar from analog pulse modulation

A modulation system in which amplitude of discrete carrier signal changes in accordance with the instantaneous amplitude of modulating signal(message signal) keeping width and position of carrier constant is called as PAM.

Pulse Amplitude Modulation (PAM)

PAM Generator

There are 2 types of PAM :

1. Natural sampling2. Flat top sampling

Types of PAM

Natural sampling

Flat top sampling

Generation and detection is easy.

Disadvantages of PAM

Added noise cannot be removed easily as it has impact on amplitude which carries information.

Transmission bandwidth is too large.

Advantages of PAM

The modulation system in which width of the discrete carrier signal changes in accordance with the instantaneous amplitude of modulating signal(message signal) keeping amplitude and position of carrier constant is called as PWM.

Pulse Width Modulation (PWM)

PWM Generator

PWM Waveform

1. Very good noise immunity.2. Its possible to separate out signal from

noise.

Disadvantages of PWM

3. Bandwidth requirement is large as compared to PAM.

Advantages of PWM

The modulation system in which position of the discrete carrier signal changes in accordance with the instantaneous amplitude of modulating signal(message signal) keeping amplitude and Width of carrier constant is called as PPM.

Pulse Position Modulation (PPM)

PPM Generator

PPM Waveform

High noise immunity.

Disadvantage of PPM

Generation and detection is complex.

Advantage of PPM

Now lets move on to digital pulse modulation.

It is the type of pulse modulation in which the group of pulses or codes are transmitted which represent binary numbers corresponding to modulating signal voltage.

Pulse Code Modulation (PCM)

PCM Generator

PCM waveform

1. Secured.2. Encoding is possible.3. Very high noise immunity.4. Convenient for long distance

communication.5. Good signal to noise ratio.

Advantages of PCM

1. Complex circuitry.2. Requires large bandwidth.3. Synchronization is required between

transmitter & receiver.

Disadvantages of PCM

In DPCM instead of transmitting digital equivalent of each quantized sampled signal the difference between the present sample value and previously sampled value is transmitted.

Differential pulse code modulation (DPCM)

DPCM Generator

1. Less signaling rate.2. Less bandwidth.

Disadvantages of DPCM

3. High bit rate.4. Needs the predictor circuit to be used

which is complex.

Advantages of DPCM

In PCM system ‘N’ no of binary digit are transmitted per quantized sample which demand high signaling rate and transmission bandwidth.

Delta modulation (DM)

DM Generator

DM waveform

1. One bit code word for output.2. Low signaling rate.3. Low channel bandwidth.

Disadvantages of DM

4. Slope overload present.5. Granular noise present.

Advantages of DM

This is the advanced version of DM. In this step size is kept variable to

avoid slope over load error and granular noise problem.

Adaptive Delta Modulation (ADM)

ADM Generator

ADM Waveform

1. Improved SNR.2. Low signaling rate.3. Reduction in slope overload and granular

noise.

Advantages of ADM

In this presentation we came across various different PULSE Modulation techniques and saw how they are transmitted and we also saw their waveforms.

We also came across advantages and disadvantages of these modulation techniques.

Conclusion :

pulse modulation

Education

Transcript of pulse modulation