2 0 1 05 02 0 04 3 2 1 0 tt 1 2 figure 46 time

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Unformatted text preview: andwidth2 beyond ¾½ . The Ì corresponding time domain function (Figure 4.6) is: where ¼ « ½ is called the roll-off factor. ܴص × Ò´ Ø Ì µ Ó×´ «Ø Ì µ Ø Ì ½ « ¾ ؾ Ì ¾ (4.13) « ¼, it reduces to the sinc function. We note that for « ¼, ܴص decays as ½ Ø¿ while for ¼, ܴص (sinc pulse) decays as ½ Ø. Hence, the raised cosine spectrum gives a pulse that is much When « 2 Another way to interpret this is that to fit ´µ into a channel bandlimited to Ï , is, the larger Ì has to be and the slower is the symbol rate. 4.6 ½·« ¾Ì Ï . Therefore, the larger « Wong & Lok: Theory of Digital Communications 4. ISI & Equalization Raised Cosine Spectrum 1 0.9 0.8 0.7 X(f) 0.6 0.5 0.4 0.3 0.2 α=0 0.1 0 −1 −0.8 −0.6 −0.4 −0.2 0 0.2 frequency/symbol rate 0.4 0.5 1 0.6 0.8 1 Figure 4.5: Raised-cosine spectrum 1 0.8 0.6 x(t) 0.4 0.2 0 1 0.5 −0.2 α=0 −0.4 −3 −2 −1 0 t/T 1 2 Figure 4.6: Time domain function of the raised-cosine spe...
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This note was uploaded on 12/13/2012 for the course EEL 6535 taught by Professor Shea during the Spring '08 term at University of Florida.

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