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Discrete-Time Fourier Transform Properties

Module by: Don Johnson

Summary: Gives various Fourier transform properties

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Figure 1: Discrete-time Fourier transform properties and relations.
Discrete-Time Fourier Transform Properties
Sequence Domain Frequency Domain
Linearity a1s1n+a2s2n a1 s1 n a2 s2 n a1S12πf+a2S22πf a1 S1 2f a2 S2 2f
Conjugate Symmetry sn sn real S2πf=S-2πf¯ S 2f S 2f
Even Symmetry sn=s-n sn sn S2πf=S-2πf S 2f S 2f
Odd Symmetry sn=-s-n sn s n S2πf=-S-2πf S 2f S 2f
Time Delay snn0 s n n0 -2πfn0S2πf 2 f n0 S 2f
Complex Modulation 2πf0nsn 2 f0n sn S2πff0 S 2 f f0
Amplitude Modulation sncos2πf0n sn 2 f0n S2πff0+S2πf+f02 S 2 f f0 S 2 f f0 2
snsin2πf0n sn 2 f0n S2πff0S2πf+f02 S 2 f f0 S 2 f f0 2
Multiplication by n nsn n sn 1-2πddfS2πf 1 2 f S 2f
Sum n=-sn n sn S2π0 S 20
Value at Origin s0 s0 -1212S2πfdf f 12 12 S 2f
Parseval's Theorem n=-|sn|2 n sn 2 -1212|S2πf|2df f 12 12 S 2f 2

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