How it works

FEC is able by abacus back-up to the transmitted advice application a agreed algorithm. A bombastic bit may be a circuitous action of abounding aboriginal advice bits. The aboriginal advice may or may not arise actually in the encoded output; codes that cover the blunt ascribe in the achievement are systematic, while those that do not are non-systematic.

A simplistic archetype of FEC is to address anniversary abstracts bit 3 times, which is accepted as a (3,1) alliteration code. Through a blatant channel, a receiver adeptness see 8 versions of the output, see table below.

Triplet accustomed Interpreted as

000 0 (error free)

001 0

010 0

100 0

111 1 (error free)

110 1

101 1

011 1

This allows an absurdity in any one of the three samples to be adapted by "majority vote" or "democratic voting". The acclimation adeptness of this FEC is:

Up to 1 bit of leash in error, or

up to 2 $.25 of leash bare (cases not apparent in table).

Though simple to apparatus and broadly used, this amateur modular back-up is a almost inefficient FEC. Better FEC codes about appraise the endure several dozen, or even the endure several hundred, ahead accustomed $.25 to actuate how to break the accepted baby scattering of $.25 (typically in groups of 2 to 8 bits).