Downsampling (Decimation) Operator
Figure 11.3 shows the symbol for downsampling by the factor . The downsampler selects every th sample and discards the rest:
the aliasing expression can be written as
upsampling (stretching) by 2 can be expressed as
, so that
as discussed more fully in §2.3.11.
Filtering and Downsampling
Upsampling (Stretch) Operator