Also known as: forward error correction, FEC

Forward error correction (FEC) adds structured redundancy to transmitted data so the receiver can correct errors on its own, without asking for retransmission — essential for broadcast and one-way radio links.¹

Forward error correction adds redundancy so the receiver can repair bit errors on its own.

How it works

Encoders such as Reed–Solomon, BCH, Golay, and convolutional codes add parity that lets the decoder fix a bounded number of errors, often aided by interleaving.

Relevance to SDR

FEC is why a digital signal stays perfect until it abruptly fails (the “cliff effect”): the decoder fixes errors until it can’t, after which audio drops out.

Sources

1. Error correction code — Wikipedia, for adding redundancy so the receiver corrects errors without retransmission. ↩

See also

• Reed–Solomon code
• BCH code
• Golay code
• Hamming code
• Convolutional code
• Interleaving

Learn it step by step

• The demodulation pipeline

From the blog

• SDR Internals, Part 9: Framing & forward error correction