Also known as: resampler, resampling

A resampler converts a sample stream from one sample rate to another.¹ SDRs rarely produce exactly the rate a decoder wants (a P25 channel needs a multiple of 4800 baud, say), so a resampler bridges the two — by a whole-number ratio or a fractional one.

A resampler changes the sample rate (here reducing it) while preserving the underlying signal.

Overview

Resampling combines interpolation, filtering, and decimation; done carelessly it causes aliasing, so a resampler always includes an anti-alias filter.

Sources

1. Sample-rate conversion — Wikipedia, on converting a stream between sample rates. ↩

See also

• Sample rate
• Decimation
• Digital filter
• Nyquist–Shannon sampling theorem

Learn it step by step

• Sample rate, bandwidth & Nyquist

From the blog

• SDR Internals, Part 5: Tuning & channelization