Also known as: cyclic redundancy check, CRC

A cyclic redundancy check (CRC) is an error-detection code that appends a checksum computed by polynomial division over the data.¹ A mismatch on receive flags a corrupted frame.

A CRC appends a checksum so the receiver can detect whether a frame arrived intact.

How it works

Unlike forward error correction, a CRC detects but does not correct errors. Frames failing the CRC are discarded. ADS-B uses CRC-24; AIS and AX.25 use CRC-16 (FCS).

Relevance to SDR

CRC validation ensures GopherTrunk only reports data frames that arrived intact.

Sources

1. Cyclic redundancy check — Wikipedia, for the polynomial-division checksum used to detect corrupted frames. ↩

See also

• Forward error correction (FEC)
• ADS-B
• Automatic Identification System (AIS)
• AX.25

Learn it step by step

• Other signals you'll meet

From the blog

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