Baseband

In Telecommunications, the term baseband refers to the band of frequencies produced by a transducer, such as a microphone, a telegraph keyer or other signal-generating device that does not need to be adapted to the environment. for which it will be transmitted.

Baseband is the signal of a single transmission on a channel, broadband means that it carries more than one signal and each of them is transmitted on different channels, up to its maximum channel number.

In transmission systems, baseband is generally used to modulate a carrier. During the demodulation process, the original baseband signal is reconstructed. Therefore, we can say that the baseband describes the state of the signal before modulation and multiplexing and after demultiplexing and demodulation.

Baseband frequencies are characterized by generally being much lower than those resulting when they are used to modulate a carrier or subcarrier. For example, the baseband signal is the one obtained from the composite video output of devices such as video recorders/players and game consoles, unlike television signals that must be modulated to be able to transport them via air (by free signal or satellite) or cable.

In facsimile transmission, the base band is the frequency of a signal equal in bandwidth to that between the zero frequency and the maximum coding frequency. In other words, if the frequency spectrum of a signal is located around the frequency f = 0 Hz, the signal is said to be “baseband”.