Also known as: decimation
Decimation reduces a signal’s sample rate by keeping only every Nth sample, after a low-pass filter removes the frequencies that would otherwise alias.1
How it works
The order matters: filter first, then decimate, so out-of-band energy cannot fold back. Once a narrow channel is isolated, decimating dramatically cuts the data the rest of the pipeline must process.
Relevance to SDR
Decimation is what makes running many channels from one capture computationally feasible.
Sources
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Decimation (signal processing) — Wikipedia, on filter-then-downsample and anti-alias requirements. ↩