[<< wikibooks] Communication Systems/Baseband and Broadband Signals
It is important to know the difference between a baseband signal, and a broad band signal. In the Fourier Domain, a baseband signal is a signal that occupies the frequency range from 0 Hz up to a certain cutoff. It is called the baseband because it occupies the base, or the lowest range of the spectrum.
In contrast, a broadband signal is a signal which does not occupy the lowest range, but instead a higher range, 1 MHz to 3 MHz, for example. A wire may have only one baseband signal, but it may hold any number of broadband signals, because they can occur anywhere in the spectrum.

== Wideband vs Narrowband ==
in form of frequency modulation.
wideband fm has been defined as that in which the modulation index normally exceeds unity.

== Frequency Spectrum ==
A graphical representation of the various frequency components on a given transmission medium is called a frequency spectrum.