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Pulse Modulation Techniques


Pulse Modulation Techniques

Pulse Amplitude Modulation (PAM)

In PAM, the amplitude of the sampled carrier pulses is varied in accordance with the amplitude of the message signal. [Read more about Pulse Amplitude Modulation (PAM) in detail ]


Pulse Width Modulation (PWM)

In PWM, the width (duration) of each carrier pulse is varied according to the amplitude of the message signal.

For example, if the carrier pulses repeat 10 times per second, then for each sampling instant the pulse width is adjusted based on the corresponding message signal value.

Note: The position of each pulse remains fixed, but the width of each pulse changes. The overall sampling period remains the same for all pulses. [Read more about Pulse Width Modulation (PWM) in detail ]


Pulse Position Modulation (PPM)

In PPM, the position (time shift) of each carrier pulse is varied according to the amplitude of the message signal.

For example, if the carrier pulses repeat 10 times per second, then for each sampling instant the pulse is shifted within the sampling period based on the corresponding message signal value.

Note: The width of each pulse remains constant, but the position of each pulse changes within the fixed sampling period. [Read more about Pulse Position Modulation (PPM) in detail ]


Similarities Between Delta Modulation (DM) and Pulse Code Modulation (PCM)

While Delta Modulation (DM) and Pulse Code Modulation (PCM) are distinct techniques, they share some similarities in that they are both methods used in signal processing. Here are some commonalities between Delta Modulation and Pulse Code Modulation:

  1. Digital Representation: Both DM and PCM involve the conversion of analog signals into a digital format. They are used to represent analog signals in a form suitable for digital communication or storage.

  2. Sampling: Both techniques involve the process of sampling, where the continuous analog signal is discretized at regular intervals. In PCM, the signal is sampled at precise intervals to capture its amplitude, while in DM, it involves the process of sampling the rate of change of the signal.

  3. Quantization: Both DM and PCM employ quantization to represent the sampled values in a finite number of discrete levels. This is essential for converting the continuous analog signal into a digital form with a limited set of values.

[Read more about 
  1. Delta Modulation (DM) in detail
  2. Pulse Code Modulation (PCM) in detail ]

Differences Between DM and PCM

  • Delta Modulation (DM): In DM, the focus is on quantizing the difference or delta between consecutive samples, rather than the absolute sample values. This simplifies the encoding process but may result in a less accurate representation, especially for rapidly changing signals.

  • Pulse Code Modulation (PCM): PCM, on the other hand, quantizes each sample independently without considering the difference between consecutive samples. It provides a more accurate representation of the original signal but may require a higher bit rate compared to DM.

In summary, while DM and PCM share common objectives of converting analog signals into a digital format through sampling and quantization, the specific techniques and approaches they use differ, leading to variations in their performance and applications.


Further Reading

  1. Online simulator for Pulse code Modulation (PCM)

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