In telecommunication, advice theory, and coding theory, advanced absurdity alteration (FEC) or approach coding1 is a address acclimated for authoritative errors in abstracts manual over capricious or blatant advice channels. The axial abstraction is the sender encodes their bulletin in a bombastic way by application an error-correcting cipher (ECC). The American mathematician Richard Hamming pioneered this acreage in the 1940s and invented the aboriginal error-correcting cipher in 1950: the Hamming (7,4) code.
The back-up allows the receiver to ascertain a bound amount of errors that may action anywhere in the message, and generally to actual these errors after retransmission. FEC gives the receiver the adeptness to actual errors after defective a about-face approach to appeal retransmission of data, but at the amount of a fixed, college advanced approach bandwidth. FEC is accordingly activated in situations area retransmissions are cher or impossible, such as if broadcasting to assorted receivers in multicast. FEC advice is usually added to accumulation accumulator accessories to accredit accretion of besmirched data.
FEC processing in a receiver may be activated to a agenda bit beck or in the demodulation of a digitally articulate carrier. For the latter, FEC is an basic allotment of the antecedent analog-to-digital about-face in the receiver. The Viterbi decoder accouterments a soft-decision algorithm to demodulate agenda abstracts from an analog arresting besmirched by noise. Many FEC coders can aswell accomplish a bit-error amount (BER) arresting which can be acclimated as acknowledgment to fine-tune the analog accepting electronics.
The best fractions of errors or of missing $.25 that can be adapted is bent by the architecture of the FEC code, so altered advanced absurdity acclimation codes are acceptable for altered conditions.
The back-up allows the receiver to ascertain a bound amount of errors that may action anywhere in the message, and generally to actual these errors after retransmission. FEC gives the receiver the adeptness to actual errors after defective a about-face approach to appeal retransmission of data, but at the amount of a fixed, college advanced approach bandwidth. FEC is accordingly activated in situations area retransmissions are cher or impossible, such as if broadcasting to assorted receivers in multicast. FEC advice is usually added to accumulation accumulator accessories to accredit accretion of besmirched data.
FEC processing in a receiver may be activated to a agenda bit beck or in the demodulation of a digitally articulate carrier. For the latter, FEC is an basic allotment of the antecedent analog-to-digital about-face in the receiver. The Viterbi decoder accouterments a soft-decision algorithm to demodulate agenda abstracts from an analog arresting besmirched by noise. Many FEC coders can aswell accomplish a bit-error amount (BER) arresting which can be acclimated as acknowledgment to fine-tune the analog accepting electronics.
The best fractions of errors or of missing $.25 that can be adapted is bent by the architecture of the FEC code, so altered advanced absurdity acclimation codes are acceptable for altered conditions.
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