Line
coding is the process of converting binary
data, a sequence of bits to a digital signal.
In other words, line coding converts a sequence of
bits to a digital signal.
At the sender, digital data are encoded in to digital
signal.
At the receiver, t
Data Communications & Networking
RZ or Return to Zero encoding
Any time the original data contain strings of consecutive 1s or
0s, the receiver can lose its place.
A solution is to some how include synchronization in the
encoded signal, something like t
Data Communication
- Signal Encoding Techniques
Encoding Techniques
1.
2.
3.
4.
Digital data, digital signal
Analog data, digital signal
Digital data, analog signal
Analog data, analog signal
2
Terms
Digital signaling
Data source (digital/analog) encoded
The problem
Many Factors can alter one or more bits of a message
during transmission.
Single bit error
Burst error (2 or more bits altered)
Solution?
Detect if there was an error.
Its easy to determine if an error has occurred.
Simple answer Y/N
C
The problem
Many Factors can alter one or more bits of a message
during transmission.
Single bit error
Burst error (2 or more bits altered)
Solution?
Detect if there was an error.
Its easy to determine if an error has occurred.
Simple answer Y/N
C
TYPES OF ERRORS & DETECTION
Basic concepts
Networks must be able to transfer data from
one device to another with complete accuracy.
Data can be corrupted during transmission.
For reliable communication, errors must be
detected and corrected.
Error de
Linear Block
Coding
Linear block code
In a (n,k) linear block code:
1st portion of k bits is always identical to the message sequence
to be transmitted.
2nd portion of (n-k ) bits are computed from message bits
according to the encoding rule and is called
1
LINE CODING &
ERROR CORRECTION
Contents
Line coding
Reasons For Using Line Coding
Properties of a Line Code
Line coding schemes
Error Correction
Line Coding
Line coding is always needed; which is a technique to
convert binary data to digital signal.
In
Navid Nasr Esfahani - 7692564
Coding Theory Assignment 3
Q.1 Let d be odd. In a (n, k, d) linear binary code, C , with at least one odd weight codeword.
a) show that if C is expurgated you get an (n, k 1, dd) code where dd > d.
Proposition 1: Exactly half
Navid Nasr Esfahani - 7692564
Coding Theory Assignment 1
12100
Q.1 Let H = 0 2 2 2 1 be the PCM for a ternary linear code C . If the received word is r = (2, 2, 2, 0, 2),
02101
use the 1-error correcting decoding algorithm to nd the original codeword.
2
1
Navid Nasr Esfahani - 7692564
Coding Theory Assignment 1
Q.1 In our rst class, we looked at rrepetition codes; i.e., where the message is repeated r times. We found that
a 3repetition code could correct 1 error. What is the smallest r for an rrepetition t
Abstract
In 1971, Mariner 9 transmitted pictures of Mars over a distance of 135
million km, with a transmitter that had a power of only 20 watts. With
such low power and taking into to account , lot of NOISE, it is
remarkable that data was received at all