DFT for a Given Frequency (Goertzel) Functions
The functions described in this section compute a single or a
number of the discrete Fourier transforms for a given frequency. Note that
the DFT exists only for the following normalized frequencies: 0, 1/
N
, 2/N,
... ( N
-1)/N
, where N
is the number of
time domain samples. Therefore you must select the frequency value from the
above set. These Intel IPP functions use a Goertzel algorithm [Mit98] and are more efficient when a small number of
DFT values is needed.
Some of the functions compute two values, not one. The
applications computing several values, for example the dual-tone multi
frequency signal detection, work faster with such functions.