Pulse modulation is a technique used to transmit analog information by sampling continuous signals at regular intervals and transmitting the signal as a series of pulses. There are two main types of pulse modulation: analog and digital. Pulse amplitude modulation (PAM) is the simplest form of pulse modulation, where each sample is made proportional to the amplitude of the original signal at the time of sampling. PAM follows the amplitude of the original signal and can reconstruct the signal through a low pass filter. It is easy to generate and demodulate PAM but requires a large bandwidth and more noise compared to other techniques.

1. PULSE MODULATION
UNIT – 2
Presented By
Mrs. M.P.Sasirekha

2. PULSE MODULATION
• Pulse modulation is a type of modulation in which the signal is
transmitted in the form of pulses. It can be used to transmit
analogue information. In pulse modulation, continuous signals
are sampled at regular intervals.
• Pulse modulation can be classified into two major types.
• Analogue: Indication of sample amplitude is infinitely variable
• Digital: Indicates sample amplitude at the nearest
predetermined level.

3. PULSE MODULATION
• A block diagram showing the basic classification of modulation
techniques is given below.

4. SAMPLING

7. PAM

8. Pulse Amplitude Modulation (PAM)
• It is the simplest form of Pulse Modulation.
• In this type of modulation, each sample is made proportional to
the amplitude of the signal at the instant of sampling.
• The PAM signal follows the amplitude of the original signal, as
the signal traces out the path of the whole wave.
• Here a signal which is sampled at Nyquist rate can be
reconstructed by passing it through an efficient Low Pass Filter
(LPF) with exact cutoff frequency.
• It is very easy to generate and demodulate PAM.
• This technique transmits the data by encoding in the amplitude
of a series of signal pulses.

9. Types of PAM
• There are two types of PAM.
1.Single Polarity PAM: A fixed DC level is added to the signal so
that the signal is always positive.
2.Double Polarity PAM: Here the pulses are both positive and
negative.

11. PAM
• it is clear that the pulse amplitude modulated signal is following the
amplitude of the message signal.
• Advantages of PAM
• Both Modulation and demodulation are simple.
• Easy construction of transmitter and receiver circuits.
• Disadvantages of PAM
• Large bandwidth is required for transmission.
• More noise.
• Here the amplitude is varying. Therefore, the power required will be
more.

12. PAM
• Applications of PAM
• Mainly used in Ethernet communication.
• Many microcontrollers use this technique in order to generate
control signals.
• It is used in Photo-biology.
• It acts as an electronic driver for LED circuits.