Agilent Technologies 93000 SOC Series Training Manual page 560

Appendix A
Time Domain vs. Frequency Domain
The traditional way of observing signals is to view them in time
domain. The time domain shows a record of what happened to a
parameter versus time. This view is similar to the paper strip
produced by a strip chart recorder.
Frequency Domain is Just Another View
In 1807, the Jean Fourier showed, that any waveform that exists in
the real world can be generated by summing up sinewaves
s(t)= S sin(ϖt+ϕ)
0
By picking the correct
amplitudes S
•
i,
0
frequencies ϖ
,
•
i
phases ϕ
• ,
i
we can generate any desired signal.
Arbitrary Waveforms Can be Generated by Adding Sinusoids
Conversely, any real world signal can be broken down into these
sinewaves. It has been proved that this combination of sinewaves
is unique—any real world signal is composed of only one
combination of sinewaves.
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