PCM Pulse Code Modulation

Pulse Code Modulation

Pulse code modulation (PCM) is a method of converting analog signals into digital signals. Quantizing is of fundamental importance in this process.

Pulse Code Modulation

  • This includes three main steps

  • Sampling

  • Quantizing
  • And coding.
  • Steps

  • Sampling

Sampling means to value different points of analog signal. Analog signal is measured at intervals. The frequency of taking it is called a sampling rate.
Sampling is a process in which the constant analog signal is measured at different periods of time to convert it into a digital signal.


The following points included in the detail of the sampling process.

Sampling of appreciation
Sampling is a process in which the amplitude is taken at various points of analog signal. These points are called samples. There is a number in which samples are taken per second. Its unit is HZ (HZ). For example, 44.1 KHZ’s sampling rate means going to 44,100 samples every second
Sample and Hold Circuit
The sampling process usually uses a sampling and hold circuit that maintains the value of analog signal for a short time so that it can be easily quiet.
Nyquist Theorem (Nyquist Theorem)
Nyquist According to theorem, the sampling rate should be minimal of the highest frequency doubled so that the original analog signal can be properly reproduced.
If the sampling rate is lower than the nyquist rate, the problem of “aliasing” may arise, in which data from different frequency is found and the original signal is damaged.
Digitization
After sampling, samples are quiet and then converted to binary numbers to make digital signals. This process is part of the full phase of PCM.


Use

Audio processing

In audio recording and play back, the sampling process is necessary to convert the sound into a digital format.
Video processing
video capture and processing also uses sampling process so that video signals can be converted into digital data.
Data Communication
Sampling is used to convert analog signals into digital signals in various communication systems.

Sampling is a basic and necessary process for converting analog signals into digital form. Understanding the importance of its accuracy and sampling rate is important for success in digital signal processing.

Plus Code Modulation (Pulse Code Modulation or PCM) is a digital scheme in which analog signals are converted into digital data.

Quantizing

Sample -made values ​​are divided into a fixed range. These values ​​are converted into a nearby potential digital value. Some information may be lost at this stage. To whom quantization is called.


Pulse code modulation (PCM) is a method of converting analog signals into digital signals. Quantizing is of fundamental importance in this process.

what is quantizing?

 how is it works?

What is its purpose.

 Definition of quantizing

Quantizing is the process of converting the continuous values ​​of a sampled analog signal to discrete levels. The purpose of this process is to convert an analog signal into a digital signal. It can be processed by computers and digital devices.

Quantizing Process Sampling

In the first step the analog signal is sampled, which means the values ​​of the signal are measured at specific time intervals. These intervals are called sampling rates.

Quantizing

which is mapped to the specified levels closest to the sampled values. These levels are called quantizing levels.

For example, if we use 8 bits, we will have 256 (2^8) quantizing levels.

Quantization Error

During the quantizing process there may be some difference between the sampled value and the quantized value. This is called quantization error. This error occurs when the original analog value is mapped to its nearest quantizing level. Due to this error, the quality of the signal may also decrease to some extent. But such error is minor and can be easily controlled.

Advantages of quantizing are as follows

 Digital Processing

With the help of quantizing, analog signals can be easily converted into digital signals that can be easily processed by computers and digital devices.

Compression

Due to quantizing, signal data can also be reduced, thereby improving storage and transmission efficiency. Fault Resistance: Digital signals are more immune to noise and errors than analog signals.

Benefits of Quantization

High quality

PCM eliminates all other noise except quantization error. The high quality of the signal retains Digital Storage: PCM data is easy to save on digital mediums.

Immediate processing

Digital signal processing is easier and faster than analog signal.

Telecommunications
Telephone networks uses PCM for sound transfer.

Video Forms

In some video formats, audio is stored in PCM format. PCM is a basic technique that modern digital communication And provides the basis for storage systems.


Disadvantages of quantizing

Listed quantization error
During this process the signal may get some error. To reduce this, higher quantizing levels can be used.

Amount of data

Higher quantizing levels require more bits. Due this amount of data can increase even more. Quantizing is an important part of pulse code modulation. which is required to convert analog signals into digital format. This process allows us to use and process analog information in digital devices.

However, there is some room for error. Overall, quantizing is an efficient and necessary technique for analog-to-digital conversion.

Coding

Quantified values are converted to binary code. Each value is given a unique binary number.

Coding in telecommunication network systems means that data or signals are converted into a specific format so that they can be sent and received efficiently over the network. It involves various techniques which are described below.

Link Layer Coding

It encodes data for error detection and error correction, such as Hamming codes or Reed-Solomon codes.

Source Coding

It is used for data compression to reduce bandwidth such as Huffman coding or run-length encoding.

Channel Coding

It is used to protect the data from noise and other types of disturbances. Such as convolutional codes or turbo codes.

The purpose of coding is to ensure accurate and efficient transfer of data. So that there is minimal data loss during communication and signal quality can be maintained.

Universal Application

PCM is used in various fields such as audio recording, video and broadcasting as well as in telecommunications. Which makes it a universal technique. For all these reasons, PCM is very important for improving the efficiency and effectiveness of communication systems.

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