The communication happens to be in analog signals that are carried in wire using different techniques for better transmission. Examples for analog signals are sound signals etc.
Analog signals are used for long distance communications as a part of conventional method and they experience the losses such as interference, distortion and security breach.
To overcome these problems by using analog signals, they are digitized using different techniques. This signal permits the communication to be accurate and clear without any losses.
Below diagram depicts the difference between the analog and digital signals. Digital signals consist of 0s and 1s which represent Low and High respectively.
There are many advantages of digital communication over analog communication as the signals are digitized. Few of them are as below -
Below diagram shows the elements that form a digital communication system.
Following are the sections of the digital communication system.
The source is the analog signal. It can be any, for example a Sound signal.
This transducer takes the physical input and converts it to electrical signal. Microphone is the best example for a transducer. This block also consists of an analog to digital converter where a digital signal is needed for coming processes.A digital signal can be represented by a binary sequence.
This will compress the data into minimum number of bits utilizing the bandwidth effectively and removes the redundant bits (unnecessary excess bits, i.e., zeroes).
Channel Encoder does the coding for correcting the errors. While the signal is transmitted, the noise can interfere and alter the signal and to avoid this, the channel encodes adds on some redundant bits to the transmitted data.
Signal from channel encoder is modulated here by a carrier. The signal is converted back to analog to make it pass through the channel or medium.
This lets the signal to transmit from the source to the receiver end.
It is the First step to perform at the receiver end. The received signal is analog one and it is demodulated and converted to digital again. Signal reconstruction happens here.
The channel decoder does the error corrections after detecting the sequence. As we did in Channel encoder, we are adding redundant bits to correct the distortions during transmission. This will recover the original signal completely.
Signal is digitized by performing sampling and quantizing to get the pure digital output without any loss of information. The source decoder recreates the source output.
This is the final block where the signal is converted to original physical form which is the same input of the transmitter. Loud speaker is an example of Output Transducer.
The output signal that is produced after the complete process. Example − The sound signal received.
This section of topic dealt with the introduction, digitization of signals, the advantages and the elements involved in digital communications. Later chapters, we will discuss in detail more about the Digital communications concept.
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