This document provides an overview of a digital communication system. It defines communication as the exchange of information through various mediums like writing or speaking. Digital communication is defined as any message transferred digitally through devices like phones or computers. The key components of a digital communication system are described as: the information source, A/D converter, source encoder, channel encoder, modulator, channel, demodulator, channel decoder, source decoder, D/A converter, and the information sink (the user). Each component is explained in 1-2 sentences with examples provided.

1. DIGITAL
COMMUNICATION SYSTEM
RAMSHA

2. What is Communication ?
 The exchanging of information by writing, speaking or using some other
medium.
OR
 Communication is the act of conveying messages from one group to
another.
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3. What is digital communication?
 Digital communication is any message transfer through digital devices.
OR
 Digital communication is any type of information transferred digitally.
Examples:
 Texting
 Fax
 Video Conference
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4. Digital Communication System 4

5. Information Source
 Information source may be classified into two categories based upon the
nature of their output i.e.
 Analog Information sources
 Discrete information sources.
In the case of analog communication, the information source is analog.
Analog information sources, such as microphone actuated by speech emit
one or more continuous amplitude signals.
In the case of a digital communication system, the information source
produces a message signal which is not continuously varying with time.
Rather the message signal is intermittent concerning time.
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6. A/D Converter
 An A/D converter is a device that converts analog signals (usually voltage)
obtained from environmental (physical) phenomena into digital format
 Conversion involves a series of steps, including sampling, quantization,
and coding.
 Example:
 Sound picked up by a microphone
 light entering a digital camera, into a digital signal.
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7. Source Encoder
 In source coding, the encoder maps the digital signal generated at the
source output into another signal in digital form.
 The mapping is one to one and the objective is to eliminate or reduce the
redundancy so as to provide an efficient representation of the source
output.
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8. Channel Encoder
 The purpose of channel encoder is to map the incoming digital signal into
a channel input.
 To control the noise and to detect and correct the errors that can occur in
the transmitted data due to the noise.
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9. Modulator
 Modulator represents the data in a form to make it compatible with the
channel
Carrier signal “High Frequency Signal” .
Demodulator
 Demodulator removes the carrier signal And reverse the process of
Modulator.
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10. Channel Decoder
 The purpose of channel decoder is to map the channel output into an
output digital signal in such a way that the effect of channel noise is
minimized.
Source Decoder
 The source decoder simply performs the inverse mapping and thereby
delivers to the user destination, a reproduction of the digital source
output. The advantage of source coding is to reduce the bandwidth of
transmission.
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11. D/A Converter
 D/A Converter reverses the operation of A/D converter.
 Needs techniques and knowledge about sampling ,quantization and
coding methods.
 Example:
 Digital speakers
 USB
 Sound Cards
Information Sink
 The User
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12. Reference:
https://www.slideshare.net/asodariyabhavesh/introduction-of-
digital-communication
http://meaningofcommunication.blogspot.com/2010/04/digital-
communication-system.html
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13. Thank You!
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