A carrier wave and modulation are two essential components in the process of transmitting information using electromagnetic waves, such as in radio or telecommunications. Here's how they differ:
Carrier Wave: A carrier wave, also known as a carrier signal, is a pure, unmodulated waveform that serves as a carrier or transport mechanism for the information being transmitted. It is a high-frequency electromagnetic wave with a constant amplitude, frequency, and phase. The carrier wave provides the means to propagate the signal through space or a transmission medium. In itself, the carrier wave does not contain any information; it acts as a framework or platform onto which the information is superimposed or modulated.
Modulation: Modulation is the process of modifying the properties of a carrier wave in order to embed or impress information onto it. It involves varying one or more characteristics of the carrier wave, such as its amplitude, frequency, or phase, according to the characteristics of the information signal. The information signal, which could be an audio signal, video signal, or data signal, carries the actual information to be transmitted.
The purpose of modulation is to effectively encode the information onto the carrier wave in a manner that can be transmitted efficiently and faithfully. There are three primary types of modulation:
Amplitude Modulation (AM): In amplitude modulation, the amplitude of the carrier wave is varied in proportion to the instantaneous amplitude of the information signal. The variations in the carrier's amplitude represent the information being transmitted. AM is commonly used for broadcasting audio signals.
Frequency Modulation (FM): Frequency modulation involves varying the frequency of the carrier wave in accordance with the instantaneous frequency of the information signal. The variations in the carrier's frequency encode the information. FM is often used for high-quality audio transmission and is commonly used in FM radio broadcasting.
Phase Modulation (PM): Phase modulation alters the phase of the carrier wave based on the instantaneous phase of the information signal. The changes in the carrier's phase represent the information. PM is widely used in various digital communication systems.
By modulating the carrier wave with the information signal, the original signal can be efficiently transmitted over long distances or through different media. At the receiving end, demodulation is performed to extract the original information from the modulated carrier wave.
In summary, a carrier wave is a pure waveform that acts as a carrier for the information, while modulation is the process of modifying the carrier wave's characteristics (such as amplitude, frequency, or phase) to embed the information onto it. The modulated carrier wave is then transmitted and demodulated at the receiver to recover the original information signal.