Definition
To recover the original information signal (such as voice or data) from a modulated radio carrier wave by removing the carrier and extracting the variations that were imposed on it during transmission.
Plain English
To pull the useful signal — the voice, the tone, the data — back out of a radio wave so it can be heard or used.
Context Anchor
Seen in discussions of aircraft communication radios, navigation receivers, and avionics that receive and process radio signals.
Derivation
From the Latin prefix 'de-' meaning 'reverse' or 'undo,' combined with 'modulate' (to vary or adjust). To demodulate is literally to undo the modulation — reversing what the transmitter did to put the signal onto the carrier wave.
Why Pilots Care
Pilots rely on demodulation to receive clear voice communications and navigation signals in aircraft radios.
Intuition Check
Demodulate does not mean simply receive a radio signal. It means extract the usable message from that signal after it has been received.
Example Sentence 1
The communications radio demodulates the incoming signal so the pilot can hear the controller's voice through the headset.
Example Sentence 2
Modern transponders demodulate interrogation signals to respond with the aircraft's identification code.