FFT Filter Series Function
The FFT Filter series function takes only one source series. In this series
function, a FFT is performed on the data in the source
series to produce a frequency signal. The frequency signal is then filtered with
a specific filter function. Finally, an inverse FFT series
function is applied to the filtered frequency signal to produce the destination series.
The filter function can be customized on the FFT Filter tab-page of the Series
Function dialog box. Normally, the filter function is a mathematical
expression that makes use of the built-in variable Freq - which
represents the FFT frequency expressed in terms of the Nyquist frequency. For example, the
filter function IF[Freq >= 0 & Freq <= 0.02, 1, 0] is a band
filter: if the FFT frequency is in the range [0, 0.02 * Nyquist Frequency], the
value of the filter function is 1; otherwise, the value of the filter function is 0.
See Also
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