Filtering Definition/Meaning:
1. The processing of a signal (by a simple electric circuit or by
some more complicated device) in such a way that the behavior of the signal is
affected in either the time domain or in a transform domain, In time-domain
filtering each element of the original signal is replaced by a sequence of
elements, proportional in amplitude to the original signal but spaced in time;
the sum (assuming linear filtering) of these sequences forms the new signal. In
transform-domain filtering the elements of the original signal are
not those of its amplitude but rather of its components under, for
example, Fourier analysis or
Walsh analysis; they are then spaced
not in time but in frequency or sequence respectively. Many other transforms are also used.
Filtering, both in the time domain and in various transform domains, is of great
importance in multiplexing. A simple but very common example of filtering in
the frequency (Fourier) domain is the use of resonant circuits to effect low-pass,
band-pass, high-pass, and band stop functions; these are much used, e.g. in
data transmission lines and
modems.
2.
See masking.
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