What do time weighting
functions do?
Fourier analysis tells us that time
and frequency are simply two alternative ways of observing a signal. By
changing the nature of a signal in the
time domain, we implicitly change
the nature of the spectrum in the frequency domain. This is exactly what
we do when we apply a weighting
function, or “time window”, to a signal. In the case of continuous signals,
the time window “slices” the data into
sections which are then analysed. In
the case of transient data, the time
window edits the time record so that
the analyzer only works on the transient, and not the portions of data
before and after the transient that
only contain noise. However, by taking such slices of the original time
domain data we have changed, or filtered, the corresponding spectrum of
our data in the frequency domain.
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