Editing Nyquist rate (section)

===Intentional aliasing===
{{main|Undersampling}}
Figure 3 depicts a type of function called [[Baseband|baseband or lowpass]], because its positive-frequency range of significant energy is [0,&nbsp;''B'').  When instead, the frequency range is (''A'',&nbsp;''A''+''B''), for some ''A''&nbsp;>&nbsp;''B'', it is called [[bandpass]], and a common desire (for various reasons) is to convert it to baseband.  One way to do that is frequency-mixing ([[heterodyne]]) the bandpass function down to the frequency range (0,&nbsp;''B'').  One of the possible reasons is to reduce the Nyquist rate for more efficient storage.  And it turns out that one can directly achieve the same result by sampling the bandpass function at a sub-Nyquist sample-rate that is the smallest integer-sub-multiple of frequency ''A'' that meets the baseband Nyquist criterion:&nbsp; f<sub>s</sub>&nbsp;>&nbsp;2''B''.  For a more general discussion, see [[Undersampling|bandpass sampling]].