Definition
An electronic circuit or device that varies (modulates) one characteristic of a carrier signal — such as its amplitude, frequency, or phase — in accordance with the variations of a second, information-carrying signal. The modulator is the stage in a transmitter that combines the audio or data signal with the radio-frequency carrier so the information can be transmitted through space.
Plain English
A part of a radio transmitter that takes the voice or data you want to send and impresses it onto the radio wave that carries it through the air. Without the modulator, the radio wave would carry no information.
Context Anchor
Seen in aircraft radio, navigation, and radar equipment discussions, especially in maintenance descriptions of transmitters.
Derivation
From the Latin modulari, meaning 'to regulate or measure.' A modulator regulates the carrier wave — adjusting it in a controlled way so it carries the intended information.
Why Pilots Care
Without a working modulator, radio transmissions would be impossible or unintelligible, preventing critical communication during flight.
Intuition Check
A modulator is not the message itself. It is the part that changes the signal so the message can ride on it.
Example Sentence 1
When the pilot keys the microphone and speaks, the modulator combines the voice with the transmitter's carrier wave so the message can be sent to the controller.
Example Sentence 2
Maintenance checked the modulator after reports of weak radio transmissions from the aircraft.