Field Guide · algorithm

Also known as: root-raised-cosine filter, RRC filter

A root-raised-cosine (RRC) filter is a pulse-shaping filter applied at both transmitter and receiver.1 Split across the link, the two halves combine into a raised-cosine response that limits bandwidth while minimising intersymbol interference.

zero at neighbouring symbol times → no inter-symbol interference
Root-raised-cosine shaping limits bandwidth while keeping symbols from smearing into their neighbours.

How it works

The roll-off factor trades bandwidth against pulse compactness. The receiver’s RRC also acts as a matched filter, maximising SNR at the sampling instant — visible as a clean eye diagram.

Relevance to SDR

Applying the correct RRC is part of demodulating digital signals that use it, sharpening symbol decisions.

Sources

  1. Root-raised-cosine filter — Wikipedia, on split RRC pulse shaping and the matched-filter pair. ↩

See also

Learn it step by step

From the blog