Line code: Difference between revisions

Revision as of 05:16, 27 June 2004

Revision as of 01:21, 30 June 2004

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For digital data transport '''line coding''' is often used. Line coding consists of representing the [[digital signal]] to be transported, by an amplitude- and time-discrete signal, that is optimally tuned for the specific properties of the physical channel (and of the receiving equipment). After line coding, the signal can directly be put on a transmission line, in the form of variations of the current.

A line coded signal must not contain a DC-component (the average signal level should be 0), because transport of a DC-component is impossible in case of long wires. An included DC-component would therefore lead to an offest at the recievingreceiving end, and thus to a higher decoding error probability.

Line coding should make it possible for the receiver to synchronise itself to the [[phase]] of the received signal. If the synchronisation is not ideal, then the signal to be decoded will not have optimal differences (in amplitude) between the various digits or symbols used in the line code. This will increase the error probability in the received data.