Introduction to Digital Communication

Introduction to Digital CommunicationBlock Diagram of Communication System

Two Types of CodingGoal of Source Coding: Code Data to represent the information efficiently To minimize the bit rate required to represent the source with specified efficiency.( Data Compression) Analog-Encode Analog source data into binary format. Digital Reduce the Size of Digital data Goal of Channel Coding: Code Data for transmitting over a noisy communication channelDigital - add redundancy to identify and correct errors Analog - represent digital values by analog signals

Source Coding Source Encoder/ DecoderChannel Coding- Channel Coder(Modulator) / Channel Decoder ( Demodulator)Source Encoder- Converts the source into Binary SequenceChannel Encoder(Modulator)-Process the binary sequence for Transmission over the channel.Channel Decoder(Demodulator)- Recreates the binary sequenceSource Decoder-Recreates the Source Output.

Binary Interface-Digital CommunicationDigital Communication Systems uses Binary(Digital) Sequences between Source and Channel InputWhy binary Interface ??????????Availability of Digital Hardware-Cheap, Reliable, SmallStandardized Binary Interface Simplifies Implementation Source Coding/Decoding done independently of the channel.

Contd..Channel Coding/Decoding Done independently of the Source

Simplifies Networking

Layering Breaks up Communication Functions in to separate Layers.

Layering-ExampleSource Coding/Decoding for analog source splits into Three Layers.

ContdSampler-Converts input waveform into sequence of samplesQuantizer Converts Each Sample into one finite set of symbolsTable Look Up-Converts back symbols into SamplesAnalog Filters- Converts back samples into Output Waveforms.

Conversion of Analog into Digital Discretization in time Sampling

Discretization of amplitude levels Quantization Converting the discrete samples to digital samples Coding/EncodingEC6501 Digital Communication Course OverviewUnit 1- Sampling & Quantization Processing Analog Source signal in Discrete Time

Unit 2- Waveform Coding Unit 3-Baseband Transmission Source Coding

Unit 4-Digital Modulation Scheme Channel CodingUnit 5- Error Control Coding Course ObjectivesTo know the principles of sampling & quantization To study the various waveform coding schemes To learn the various baseband transmission schemes To understand the various Band pass signaling schemes To know the fundamentals of channel coding

Course Outcomes CO1 :Design PCM systems CO2 :Design and implement base band transmission schemes CO3 :Design and implement band pass signaling schemes CO4:Analyze the spectral characteristics of band pass signaling schemes and their noise performance CO5 :Design error control coding schemes