The coded system can be divided into encoder/decoder pair and a discrete channel between them. Typically more samples are needed to represent the channel part in a simulation.
Source Decoder: Reverse the operation of the source encoder to determine the most probable sequence that could have caused the output. Often the modulator-channel-demodulator are thought of as a super channel with a finite number of …
Digital modulation (or channel encoding) is the process of converting an input sequence of bits into a waveform suitable for transmission over a communication channel. Demodulation (channel decoding) is the corresponding process at the receiver of converting the received waveform into a (perhaps noisy) replica of the input bit sequence.
Block Diagram of Digital Communication System
Source Decoder : The resultant signal is once again digitized by sampling and quantizing so that the pure digital output is obtained without the loss of information. The source decoder recreates the source output.
Following Shannon's separation theory resulted in major advances on source coding (e.g., rate-distortion optimal coders and advanced en-tropy coding algorithms) and channel coding (e.g., Reed-Solomon codes, Turbo codes, and Tornado codes).
The channel encoder/decoder improve the reliability of the transmission of the source-encoded information through the channel. These two blocks jointly embody the topic of this tutorial.
Explain image compression with the help of block diagram.
The source encoder removes the input redundancies while the channel encoder increases the noise immunity of the source encoders. The decoder consists of a channel decoder and a source decoder. The function of the channel decoder is to ensure that the system is immune to noise.
The Source encoder ( or Source coder) converts the input i.e. symbol sequence into a binary sequence of 0‟s and 1‟s by assigning code words to the symbols in the input sequence.
The Source encoder ( or Source coder) converts the input i.e. symbol sequence into a binary sequence of 0’s and 1’s by assigning code words to the symbols in the input sequence. At the receiver, the source decoder converts the binary output of the channel decoder into a symbol sequence. Aim of the source coding is to remove the redundancy ...
Simplest Example of channel encoding A sequence of binary digits is mapped, one at a time, into a sequence of signals from the constellation {1,−1}. Usually the mapping is 0→ 1 and 1 →−1. The sequence of signals, u1,u2,... , is mapped to the waveform k uksinc T t − k. With no noise, no delay, and no attenuation, the received waveform is
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