Model of Digital Communication system – Channel Encoder and decoder

Channel encoder and decoder : Channel Encoder :After converting message or information signal in the form of binary sequence by the source encoder, the signal is transmitted to the channel. The channel acts as noise and interference to signal being transmitted. Therefore, errors are introduced in the binary sequence received at the receiver. To avoid these errors channel encoding is done. The channel encoder acts as some redundant binary bits to the input sequence.      Example: The code word from the source encoder is 3- bits long and one redundant bit is added in channel encoder. If it an even parity then the number of 1's in the encoded word remain even. At the receiver if odd number of 1's are detected then reciver comes to know that there is an error in the receiver signal.Channel Decoder :The channel decoder is able to detect errors in the bit sequence and reduce the effects of channel noise interference. The extra bits/...
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Elements of Digital Communication:

Model Digital Communication System :      The purpose of this system is to transmit the message or square of symbols coming out of the source to a destination point.      The source and destination points are separated through a communication channel Model of Digital communication system * Discrete information source : The information source generates the message signal to be transmitted an analof information source may be transformed into a discrete information source through the process of sampling and quantization. The discrete information sources are charectarized by the following Parameters:  Source : These are the letter, digits or special charectar available in the information source. Source Alphabet Probability : Each source alphabet  from information source has independent occurrence rate in the sequence.Example: Letter or words (a, e, i, o, u) occurs frequently in the source. Symbol Rate: It is the rate at which the information source generates source alphabet and represented in symbol/ sec unit. Information Rate: This parameter defines the average information content of the symbols. Entropy...
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