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The WP02 Spectral Analysis package, with FFT (Fast Fourier
Transform), reveals signal characteristics not visible in the
time domain and adds the power of frequency domain
analysis to your oscilloscope. FFT converts a time domain
waveform into frequency domain spectra similar to those of
a spectrum analyzer, but with important differences and
added benefits.
:K\ 8VH ))7" For a large class of signals, greater insight can be gained by
looking at spectral representation rather than time description.
Signals encountered in the frequency response of amplifiers,
oscillator phase noise and those in mechanical vibration analysis
-- to mention just some applications -- are easier to observe in
the frequency domain.
If sampling is done at a rate fast enough to faithfully approximate
the original waveform (usually five times the highest frequency
component in the signal), the resulting discrete data series will
uniquely describe the analog signal.
This is of particular value when dealing with transient signals
because, unlike FFT, conventional swept spectrum analyzers
cannot handle them.
7KHRU\ %HKLQG ))7 Spectral analysis theory assumes that the signal for
transformation be of infinite duration. Since no physical signal
can meet this condition, a useful assumption for reconciling
theory and practice is to view the signal as consisting of an
infinite series of replica of itself. These replica are multiplied by a
rectangular window (the display grid) that is zero outside of the
observation grid.