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.