Also known as: demodulation

Demodulation recovers the original modulating information from a carrier — the inverse of modulation.¹ For FM/FSK it tracks instantaneous frequency; for PSK it tracks phase.

Demodulation recovers the original modulating signal from the carrier — the step before decoding bits.

How it works

The demodulator outputs a continuous, noisy stream that contains the symbols; clock recovery then slices it into discrete symbols, which decoding turns into bits. Demodulation handles the waveform; decoding handles the data.

Relevance to SDR

Choosing the matching demodulator for a signal’s modulation is the core of recovering it; the constellation visualises this stage.

Sources

1. Demodulation — Wikipedia, on recovering the modulating signal as the inverse of modulation. ↩

See also

• Modulation
• Clock recovery
• Costas loop
• Constellation diagram
• Software-defined radio (SDR)

Learn it step by step

• The demodulation pipeline

From the blog

• SDR Internals, Part 6: Demodulation