Carrier wave

A periodic waveform whose amplitude, frequency, or phase is varied to carry information. In radio systems, it is commonly a sinusoidal electromagnetic wave.

Modulation: The process of varying a carrier’s properties according to an information-bearing signal. It is the general operation that turns a steady carrier into a signal-bearing waveform.
Periodic function: A function that repeats its values at fixed intervals. A carrier wave repeats regularly, making periodicity its defining waveform property.
Radio communication: The transmission of information using radio-frequency electromagnetic waves. Radio systems use modulated carriers to send information through space.
Baseband transmission: The transmission of a signal in its original frequency range without shifting it onto a higher-frequency carrier. It sends information directly rather than translating it to a carrier frequency.
Amplitude modulation: A modulation method that varies a carrier’s amplitude in proportion to the message signal. It carries information in changes to the carrier’s amplitude.
Frequency: The number of cycles of a repeating event completed per unit time. The carrier’s frequency determines where its signal is centered in the spectrum.
Amplitude-shift keying: A digital modulation method that represents data by switching a carrier’s amplitude among levels. It uses discrete carrier-amplitude changes to encode digital symbols.
Passband: A range of frequencies around a center frequency that a communication channel or filter passes. A modulated carrier places the signal within a channel’s passband.
Frequency modulation: A modulation method that varies a carrier’s instantaneous frequency according to the message signal. It encodes the message in shifts of the carrier’s frequency.
Wavelength: The distance between corresponding points on successive cycles of a wave. For an electromagnetic carrier, wavelength corresponds to its frequency and propagation speed.

Linked from 11 pages