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ps:cap3-transformata-fourier-am [2026/11/11 12:34] – Cap 3 revizuit: de la zero, exemple numerice, casete De ce, teorie ca la examen apacheps:cap3-transformata-fourier-am [2026/11/11 12:46] (current) – Cap 9 nou: filtre FIR; corectat trimiteri la Cap 0 §4.3 apache
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 Luam ca mesaj cel mai simplu semnal: $s(t) = \cos(2\pi\cdot 1\,t)$ (frecventa 1 Hz). Il inmultim cu $\cos(2\pi\cdot 10\,t)$ (frecventa 10 Hz). Luam ca mesaj cel mai simplu semnal: $s(t) = \cos(2\pi\cdot 1\,t)$ (frecventa 1 Hz). Il inmultim cu $\cos(2\pi\cdot 10\,t)$ (frecventa 10 Hz).
  
-**Pas 1 — scriem fiecare cosinus ca doua exponentiale** (formula din [[ps:cap0-baze|Cap 0 §4.2]]: $\cos x = \frac12 e^{jx} + \frac12 e^{-jx}$):+**Pas 1 — scriem fiecare cosinus ca doua exponentiale** (formula din [[ps:cap0-baze|Cap 0 §4.3]]: $\cos x = \frac12 e^{jx} + \frac12 e^{-jx}$):
  
 $$ \cos(2\pi\cdot 1\,t) = \tfrac12 e^{j2\pi\cdot 1\,t} + \tfrac12 e^{-j2\pi\cdot 1\,t} \qquad \text{(linii de } \tfrac12 \text{ la } +1 \text{ si } -1 \text{ Hz)} $$ $$ \cos(2\pi\cdot 1\,t) = \tfrac12 e^{j2\pi\cdot 1\,t} + \tfrac12 e^{-j2\pi\cdot 1\,t} \qquad \text{(linii de } \tfrac12 \text{ la } +1 \text{ si } -1 \text{ Hz)} $$
ps/cap3-transformata-fourier-am.txt · Last modified: by apache