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FFT
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BIN I FOURIER NHANH (FFT)
1. Tm tt l thuyt Tnh DFT & IDFT:
Tnh trc tip
FFT - Chia tr: phn chia theo thi gian hoc theo tn s
C s 2 C s 4 Tch c s
2. Bi tp cng c l thuyt
2.1. Cho dy hu hn
0,5,0,1,5,1,2,5,2,3)(nx
Hy tnh DFT 8 im ca dy trn theo hai cch sau :
a. Bng thut ton FFT c s 2 phn chia theo thi gian. b. Bng thut ton FFT c s 4 phn chia theo thi gian.
2.2. Cho dy
0,0,0,0,2
1,
2
1,
2
1,
2
1)(nx
Tm DFT 8 im ca tn hiu x(n) s dng phng php FFT c s 2 phn chia theo min tn s.
2.3. Xt FFT c s 2 ca 1024 im
a. C bao nhiu tng tnh ton? b. Trong mi tng c bao nhiu php nhn? c. Ton b FFT c bao nhiu php nhn?
2.4. Tnh DFT 16 im ca chui sau
1502
cos)( nnnx
a. S dng phng php tnh ton FFT c s 4 phn chia theo min thi gian b. S dng phng php tnh ton FFT c s 4 phn chia theo min tn s