Editing Baseband (section)

== Modulation ==
A signal at baseband is often used to [[modulation|modulate]] a higher frequency [[carrier signal]] in order that it may be transmitted via radio. Modulation results in shifting the signal up to much higher frequencies (radio frequencies, or RF) than it originally spanned. A key consequence of the usual [[double sideband|double-sideband]] [[amplitude modulation]] (AM) is that the range of frequencies the signal spans (its spectral [[Bandwidth (signal processing)|bandwidth]]) is doubled. Thus, the RF bandwidth of a signal (measured from the lowest frequency as opposed to 0&nbsp;Hz) is twice its baseband bandwidth. Steps may be taken to reduce this effect, such as [[single-sideband modulation]]. Conversely, some transmission schemes such as [[frequency modulation]] use even more bandwidth.

The figure below shows AM modulation:

[[File:Baseband to RF.svg|frame|center|Comparison of the equivalent baseband version of a signal and its AM-modulated (double-[[sideband]]) RF version, showing the typical doubling of the occupied bandwidth.]]