8/2/2019 FinalDSP10-11

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DSP 2010/2011 Ra : PGS TS LTin Thng, Th.S. Lng Quang, Th.S. N. c Hong, Th.S. NCh Ngc

Thi HK 1-2010/2011 Ngy 9/1/2011

Trng HBK TpHCMKhoa in in t

THI HC K I / 2010 2011Mn thi : X L S TN HIUNgy thi: 09/1/2011 - Thi gian: 90 pht

Sinh vin khng s dng ti liu

PHN 1: (60 ) Cc cu hi c bn (20 /cu)

1. Dng tnh cht chp (Convolution property) ca php bin i Z, tma. Kt qu y(n)=x(n)*h(n) x(n) = {3, 2, 0, -1}, h(n) = {-1, 1, 2}.

b. Kim tra kt qu cu 1.a bng cch dng bng tnh LTI cho tch chp.c. Vit phng trnh quan h vo ra I/O tng ng vi gi thit cu 1.a.d. V thc hin dng trc tip kt qu cu 1.c.

2. Dng cng thc nh ngha ca php tnh DFT/FFT, xc nh s php tonnhn s dng cho vic tnh ton chui tn hiu x(n) c chiu di 1024 cho cctrng hp sau:

a. Tnh trc tip 8-point-DFT.b. Tnh 8-point-DFT cho tn hiu xp li (wrapped signal) x(n) ca x(n).c. Tnh 8-point-DFT dng thut ton tnh nhanh FFT.

3. Hay neu cong thc nh ngha cua bien oi Z va nh ngha cua mien hoi tuROC.

a. Dung nh ngha nay chng minh tnh chat sau cua bien oi Z:Neu: x

ZRzXnx ROC),()(

Th: xZ R

dz

zdXznnx ROC,

)()(

b. Ap dung tnh chat nay tm bien oi Z ngc cua||||:ROC),1log()( 1 azazzX

8/2/2019 FinalDSP10-11

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DSP 2010/2011 Ra : PGS TS LTin Thng, Th.S. Lng Quang, Th.S. N. c Hong, Th.S. NCh Ngc

Thi HK 1-2010/2011 Ngy 9/1/2011

PHN 2: (40 ) Chn 2 trong 4 cu hi sau (20 /cu)

4. Tnh cc DFT sau s dng thut ton FFT c s 2a. Tnh DFT-4 im ca cc chui sau:

1 21, 2, 1, 2 ; 1, 2, 3, 4x n x n b. S dng kt qu ca cu a tnh DFT-8 im ca chui sau:

3 1, 1, 2, 2, 1, 3, 2, 4x n 5. Xc nh bin i Z v Z ngc:

a. Xc nh bin i Z v ROC ca chui sau: 0cosx n n u n

b. Xc nh tt c nhng li gii cho chui x(n) c bin i Z sau:

21 1

11 1

X zz z

6. Thit k b lc thng thp FIR pha tuyn tnh dng phng php ca s chnht. Cho bit b lc c cc thng s yu cu nh sau: tn s ct fc=12kHz, tns ly mu fs=48kHz, v chiu di b lc N=7.

a. V p ng tn s l tng ca b lc nu trnb. Dng nh ngha DTFT tnh p ng b lc min thi gianc. p dng ca s ch nht N=7 tnh 7 gi tr cho p ng b lc min

thi gian (ch gi tr n trong khong [-3,3].

7. Cho he thong nhan qua co ham truyen nh sau:22 25.01

4

25.01

5)(

zzzH

a. Xac nh ap ng xung h(n) va mien hoi tu ROC cua he thong.b. Ve s o thc hien he thong dang trc tiep (direct form)c. Ve s o thc hien he thong dang chnh tac (canonical form)d. Ve s o thc hien he thong dang ghep noi tiep (cascade form)e. Ve s o cc/zero cua he thong va phac thao ap ng bien o cua

ham truyen tren trong mien tan so.

HtGood lucks!