Today’s world is heavily dependent on Digital Communication. What ever we use for any sort of communication, it has a niche touch of Digitization. This post will discuss about various aspects of Digital Communication such as Introduction, Basic components, How Digital Signal Communication Process works and its various advantages over Analog Signal Communication.
Introduction to Digital Communication
Digital Communication is defined as the process by which Digital devices communicate information digitally. The communication that occurs in our daily life is in the form of signals such as sound signals. These sound/ audio signals are normally analog in nature. For such communication via sound signals, we must be near the source of sound signal, at least within our hearing range. But what if the source and receiver are at a long distance? In case if the communication needs to be established over a distance, the analog signals are sent through wire, using different techniques for effective and efficient transmission.
Fig. 1 – Digital Communication – Introduction, Basic Components and Advantages
Why Digitization is Needed for Communication?
The traditional methods of communication were using analog signals for long distance communications. Due to the long distance, the analog signal has to go through many losses such as distortion, intervention or interference and even security breach too.
To minimize and overcome these types of losses, the signals are now digitized using different techniques. With the use of digitized signals, the communication become more clear and accurate with minimum or no losses.
Fig. 2 – Representation of Digital and Analog Signals
The Fig. 2 above represent analog and digital signals. The digital signals consist of 1s and 0s which indicate High and Low values respectively.
Basic Components of a Digital Communication System
Broadly, every digital Communication system consists of these basic components.
- Input Transducer
- Analog to Digital Converter
- Source Encoder
- Channel Encoder
- Digital Modulator
- Communication Channel
- Digital Demodulator
- Digital to Analog Converter
- Channel Decoder
- Source Decoder
- Output Transducer
- Output Signal
Fig. 3 – Basic Components of Digital Communication System
How Digital Communication Process Works?
The source consists of an analog signal.
For example: A Sound signal
2. Input Transducer
This block consists of input transducer which takes a physical input and converts it to an electrical signal For example: Microphone
3. Analog to Digital Converter
This electrical signal from Input Transducer is further processed and converted into Digital Signal by Analog to Digital Converter.
Fig. 4 – Analog to Digital Conversion
4. Source Encoder
The source encoder compresses the data into lowest number of bits. This procedure helps in efficient operation of the bandwidth. It removes the unnecessary bits.
5. Channel Encoder
The channel encoder, here the coding is done for error correction. During the transmission of the signal, due to the sound in the channel, the signal may get distorted. To avoid this, the channel encoder adds some unnecessary bits to the transmitted data. These bits are the error correcting bits.
6. Digital Modulator
Here the signal which is to be transmitted is modulated by a carrier. The carrier is used for for effective long distance transmission of data.
7. Digital to Analog Converter
The digital signal extracted from the carrier is then converted again into analog so that the signal can be passed effectively through the channel or medium.
The channel provides a path for the signal and permits the analog signal to transmit from the transmitter end to the receiver end.
9. Digital Demodulator
This is the place from where the data retrieving process is started at the receiver end. The received signal is demodulated and again converted from analog to digital. The signal gets rebuild here.
10. Channel Decoder
The channel decoder does the error corrections post sequence detection. The distortions which might take place during the transmission are corrected by adding some additional bits. Addition of these bits help in the complete recovery of the original signal.
11. Source Decoder
The resulting signal is again digitized by sampling and quantizing. This is done to obtain the unadulterated digital output without any loss of information. The source decoder creates again the source output.
12. Output Transducer
This is the final block which converts the signal into its original form (which was at the input of the transmitter). It converts the electrical signal into physical output.
For example: Speaker
13. Output Signal
This is the output for which the whole process is done.
For example: The sound signal received
Fig. 5 – Advantage of Digital Signal
Advantages of Digital Communication over Analog Communication
Digital Communication has many advantages over Analog Communication. Some of them are listed below: –
- The specific signal level of the digital signal is not very important. Due to this, digital signals are quite unaffected by the flaws of electronic systems that may spoil analog signals.
- The configuration process of digital signals is easier than analog signals.
- Encryption works better in Digital Signals (using codes).
- Digital circuits are more consistent and reliable.
- Digital circuits are easy to design (normally).
- The cost of manufacturing Digital Circuits is lesser than Analog Circuits.
- Digitals Signals do not get corrupted by noise, interference, and distortions.
- Cross-talking is very rare in Digital Communication.
- Long distance data transmission is more easy and cheap with Digital Signals.
- The hardware implementation in digital circuits is much more flexible if compared to analog circuits.
- The method of combining digital signals using Time Division Multiplexing (TDM) is easier than the method of combining analog signals using Frequency Division Multiplexing (FDM).
- Digital signals can be saved and extracted more easily than analog signals.
- Most of the digital circuits have almost common encoding techniques and therefore similar devices can be used for a number of purposes.
- Digital Communication supports multi dimensional transmissions simultaneously.
- The capability of the channel is efficiently utilized by digital signals.
- The signal is unchanged as the pulse needs a high interruption to change its properties, which is very complex.
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