Block Diagram of Digital Communication System

A block diagram of digital communication system represents the various functional elements and stages involved in transmitting and receiving digital data.

Block Diagram of digital communication system having three sections

1. Transmitter Section
2. Transmission Channel
3. Receiver Section

Block diagram of Digital Communication System

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1.Transmitter Section

It include various functional elements such as Information Source, Input Transducer, Source Encoder, Channel Encoder and Digital Modulator through we can transmitted our digital information.

• Information source: It generate information which is to be transmitted. It could be a Audio, Video, Image, discreate data e.g. computer generated output. These signals are non-electrical quantities and hence can not be processed directly in a digital communication system.
• Input Transducer: A transducer is a device which converts non-electrical quantity into electrical signal such as microphone. So, the output of the information source is a non-electrical quantity given to the input transducer, the input transducer convert this non-electrical quantity into electrical quantity. This block also consists of an analog to digital converter, it convert analog signal (electrical signal) into digital signal needed for further processes.
• Source Encoder: The function of source encoder is used to compress the data into minimum number of bits. This helps in effective utilization of the bandwidth. It removes the redundant bits or unnecessary excess bits that is zeros from the input data. The output of the source encoder is called source code.
• Channel Encoder: Channel Encoder provide noise immunity by adding a redundancy bit in the message data. These redundancy bits are called error-correcting bits. When the signal is transmitted over a communication channel, the signal may get altered due to the noise, distortion, and interference in the channel. Hence, the channel encoder adds some redundant bits to the message data in order to provide error-free data on the receiver side. The output of the source encoder is called channel code.
• Digital Modulator: The digital modulator converts discrete binary data (0s and 1s) into continuous analog signals that can be transmitted over a communication medium. This process is necessary because most communication channels are analog in nature. Then modulates the carrier wave with the digital data to create a modulated signal. This process involves changing certain characteristics of the carrier wave, such as its amplitude, frequency, or phase, based on the digital input. Common modulation techniques include Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK), and Quadrature Amplitude Modulation (QAM).

2. Communication Channel

A communication channel refers to the physical or logical media via information or data is transmitted from a sender to a receiver. There are two main types of communication channels: guided and unguided.

Guided Communication Channel transmission of signals occurs through a physical medium like Twisted Pair Cable, Coaxial Cable, Optical Fiber etc.

Unguided Communication Channel also known as Wireless Channel, propagates signals (data) through free space like Radio Waves, Microwaves, Infrared etc.

3.Receiver Section

It include various functional elements such as digital demodulator, source decoder, channel decoder, source decoder, output transducer through which we can recover our original information.

• Digital Demodulator: Digital demodulator is function just opposite to digital modulator. It is a devise used to converting the received analog signal (usually a modulated carrier) back into its original digital form. Demodulator is done by modulation scheme used for encoding the data, such as amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), or quadrature amplitude modulation (QAM). The output of digital demodulator given to source decoder.
• Channel Decoder: After detecting the received signal, channel decoder apply some error corrections mechanism. The signal might get distorted during the transmission. This is corrected by adding some redundant bits to the signal. This addition of bits helps in the complete recovery of the original signal.
• Source Decoder: The source decoder reverses the compression process applied at the transmitter to recover the original digital data.
• Output Transducer : A output transducer is a device which converts electrical signal into non-electrical quantity. So, the output of the information source is a electrical quantity given to the output transducer, the output transducer convert this electrical quantity into non-electrical quantity.
• Output Signal : Output signal is a original massage signal which is produced after the whole process.

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block diagram of digital communication system

block diagram of digital communication system