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(
(
Sec. 2–2 Fourier Transform and Spectra 57
(
t
–– T
1
T
T
– –– –– t
2 2
(a) Rectangular Pulse
1.0
sin x
Sa(x) = –––– x
0.8
0.6
0.4
0.2
0.0
–4∏ –3∏ –2∏ –∏
–0.2
∏ 2∏ 3∏ 4∏
x
(b) Sa(x) Function
(
–– t
T
1.0
– T
T
t
(c) Triangular Function
Figure 2–5 Waveshapes and corresponding symbolic notation.
T Sa (pTt) 4 ß a- f T b =ßa f T b
Replacing the parameter T by 2W, we obtain the Fourier transform pair.
2W Sa (2pWt) 4 ßa f
2W b
(2–56)