Showing posts with label PCM. Show all posts
Showing posts with label PCM. Show all posts

PCM and DPCM using SIMULINK


  • AIM:

To generate a Pulse Code Modulation using simulink.


  • SOFTWARE REQUIRED:

1.Matlab
2.Simulink


  • BLOCKS REQUIRED:

1. Sine wave generator
2. Pulse generator
3. Product
4. Quantizer
5. Encoder
6. Integer to bit converter
7. Scope

  • BLOCK DIAGRAM for PCM:




  • OUTPUTS OBTAINED:

quantized output

encoded output


PCM


  • BLOCK DIAGRAM FOR DPCM:

  • OUTPUTS OBTAINED:

after introducing a delay element

quantization

encoded signal


  • INFERENCE

Pulse Time Modulation is also known as Pulse Width Modulation or Pulse Length Modulation. In PWM, the
samples of the message signal are used to vary the duration of the individual pulses. Width may be varied by
varying the time of occurrence of leading edge, the trailing edge or both edges of the pulse in accordance with modulating wave. It is also called Pulse Duration Modulation.

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Pulse Code Modulation (PCM) and Demodulation

1. ABSTRACT:
Pulse Position Modulation (PPM) is a form of signal modulation in which M message bits are encoded by transmitting a single pulse in one of 2*2*2*2...... (M times) or (2 to the power M) possible time shifts. This is repeated every T seconds, such that the transmitted bit rate is M/T bits per second. It is primarily useful for optical communication systems, where there tends to be little or no multipath interference.
2. BLOCK DIAGRAM:



3. CONCEPT:
Message Signal (Sine Wave) with low frequency is passed through Carrier Signal (Sawtooth Wave) with high frequency (Fc>2Fm) and then do Pulse Width Modulation (PWM) of the message signal. To demodulate PPM signal use Phase Looked Loop (PLL) and Low Pass Filter (LPF) as shown in block diagram. 

4. SNAP-SHOTS:
Ø Message Signal:
Frequency=100Hz

Ø Carrier Signal:
Frequency=500Hz

Ø PWM Output:

Ø PPM Output:


Ø Demodulated Message Signal:

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