Tn Dsp 2015-01-18 Sinhvien

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Trng i Hc Bch Khoa Khoa in in T B Mn Vin Thng

X L S TN HIU

Ti liu th nghim

B MN VIN THNG- 2015

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Mc lc

Mc lc ................................................................................................................................................... 2

Mc lc hnh v ..................................................................................................................................... 6

Mc lc cc bng ................................................................................................................................... 7

GII THIU ......................................................................................................................................... 8

BI 1: GII THIU KIT DSP V MATLAB ................................................................................... 1

1. MC CH TH NGHIM ............................................................................................................. 1

2. THIT B TH NGHIM ................................................................................................................ 1

3. GII THIU KIT X L S C6713 DSK (DSP STARTER KIT) ............................................. 1

3.1. Kit C6713 DSK ............................................................................................................................... 1

3.2. Code Composer Studio (CCS) ....................................................................................................... 2

3.2.1. Cc tp tin h tr .................................................................................................................. 3

3.2.2. Cc v d lp trnh trn DSK ................................................................................................... 3

4. GII THIU MATLAB V CNG C SPTOOL ..................................................................... 12

4.1. Matlab ........................................................................................................................................ 12

4.2. Thit k b lc s bng cng c SPTool ..................................................................................... 16

BI 2: LY MU V LNG T HA TRN KIT C6713 DSK .............................................. 22

1. MC CH TH NGHIM ........................................................................................................... 22

2. THIT B TH NGHIM .............................................................................................................. 23

3. C S L THUYT ...................................................................................................................... 23

3.1. Gii thiu.................................................................................................................................... 23

3.2. Ly mu tn hiu ......................................................................................................................... 23

3.3. Lng t v m ha ................................................................................................................... 24

4. CHUN B TH NGHIM ............................................................................................................ 25

5. TIN HNH TH NGHIM ......................................................................................................... 26

Ly mu tn hiu ................................................................................................................................ 26

Lng t ha tn hiu ....................................................................................................................... 31

BI 3: B LC FIR/IIR TRN KIT C6713 DSK .......................................................................... 39

1. MC CH TH NGHIM ........................................................................................................... 39

2. THIT B TH NGHIM .............................................................................................................. 40

3. C S L THUYT ...................................................................................................................... 40

3.1. B lc FIR .................................................................................................................................... 40

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3.2. B lc IIR..................................................................................................................................... 41

4. CHUN B L THUYT TH NGHIM .................................................................................... 45

4.1. B lc FIR .................................................................................................................................... 45

4.2. B lc IIR..................................................................................................................................... 47

5. TIN TRNH TH NGHIM ........................................................................................................ 52

5.1. Cc b lc FIR ............................................................................................................................. 52

5.1.1. B lc FIR chn di .............................................................................................................. 52

5.1.2. B lc FIR thng di............................................................................................................. 59

5.1.3. B lc FIR thng cao ............................................................................................................ 63

5.1.4. B lc FIR multiband ........................................................................................................... 67

5.2. Cc b lc IIR .............................................................................................................................. 72

5.2.1. B lc IIR chn di ............................................................................................................... 72

5.2.2. B lc IIR thng thp ........................................................................................................... 78

5.2.3. Thc hin b lc IIR thng di ............................................................................................ 81

5.2.4. Thit k b lc IIR multiband .............................................................................................. 84

BI 4: THC HIN FFT TRN KIT C6713 DSK ......................................................................... 90

1. MC CH TH NGHIM ........................................................................................................... 90

2. THIT B TH NGHIM .............................................................................................................. 90

3. C S L THUYT ...................................................................................................................... 91

3.1. DFT ............................................................................................................................................. 91

3.2. FFT .............................................................................................................................................. 91

4. CHUN B L THUYT TH NGHIM .................................................................................... 93

5. TIN TRNH TH NGHIM ........................................................................................................ 98

5.1. Thc hin FFT-128 im ............................................................................................................ 98

5.2. Thc hin FFT-256 im .......................................................................................................... 102

BI 5: IU CH PAM V PWM ................................................................................................ 109

1. MC CH TH NGHIM ......................................................................................................... 109

2. THIT B S DNG ................................................................................................................... 109

3. C S L THUYT .................................................................................................................... 110

3.1. Gii thiu.................................................................................................................................. 110

3.2. Mt s k thut iu ch c bn ............................................................................................. 110

3.2.1. Cc k thut iu ch tng t ........................................................................................ 110

3.2.2. Cc k thut iu ch s ................................................................................................... 111

3.2.3. iu ch s di nn (Digital baseband modulation) ......................................................... 111

3.2.4. Cc phng php iu ch xung ...................................................................................... 111

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3.2.5. iu ch bin xung (PAM) ........................................................................................... 112

3.3. iu ch rng xung (PWM) ................................................................................................. 113

3.4. L thuyt c bn ....................................................................................................................... 114

4. CHUN B L THUYT TH NGHIM .................................................................................. 115

4.1. iu ch PAM ........................................................................................................................... 115

4.2. iu ch PWM ......................................................................................................................... 118

5. TIN TRNH TH NGHIM ...................................................................................................... 119

5.1. Thc hin mch iu ch PAM trn kit C6713 DSK ................................................................. 119

5.2. Thc hin mch iu ch PWM trn kit C6713 DSK ................................................................ 127

BI 6: PHN TCH TN HIU TING NI ................................................................................ 132

V NG DNG X L TING NI ............................................................................................ 132

1. MC CH TH NGHIM ......................................................................................................... 132

2. THIT B TH NGHIM ............................................................................................................ 133

3. L THUYT ................................................................................................................................. 133

3.1. Gii thiu.................................................................................................................................. 133

3.2. C s l thuyt ......................................................................................................................... 134

4. CHUN B TH NGHIM .......................................................................................................... 137

5. TIN HNH TH NGHIM ....................................................................................................... 139

5.1. c lng bng thng v kho st s phn b nng lng ................................................... 139

5.2. Xc nh tn s ly mu ti thiu ............................................................................................. 141

5.3. Trit nhiu nng cao cht lng ting ni ............................................................................... 143

5.4. Tch ting ni ra khi on tn hiu thu c ........................................................................ 146

5.5. Nhn dng gii tnh. ................................................................................................................. 148

5.6. Phn m rng ........................................................................................................................... 151

BI 7: X L NH S ................................................................................................................... 152

1. MC CH TH NGHIM ......................................................................................................... 152

2. THIT B S DNG ................................................................................................................... 152

3. L THUYT V CHUN B TH NGHIM ........................................................................... 152

3.1. Gii thiu nh s ...................................................................................................................... 153

3.1.1. nh s: .............................................................................................................................. 153

3.1.2. Tc v i s: ..................................................................................................................... 155

3.1.3. Cc loi nhiu nh: ............................................................................................................ 156

3.1.4. Cc loi b lc theo sp xp th t: ................................................................................. 158

3.2. Lm sc nt hnh: ..................................................................................................................... 159

4. TIN TRNH TH NGHIM ...................................................................................................... 160

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4.1. To v trit nhiu mui tiu..................................................................................................... 160

4.1.1. c nh gc vo ................................................................................................................ 160

4.1.2. Lc nh dng b lc trung v ............................................................................................. 161

4.1.3. Lc nh dng b lc trung v c sn medfil2 .................................................................... 163

4.2. Gim nhiu tun hon ............................................................................................................. 164

4.2.1. To nhiu tun hon ......................................................................................................... 164

4.2.2. Lc nhiu tun hon.......................................................................................................... 166

4.3. Lm nhe v lm sc nt hnh.................................................................................................. 168

4.3.1. Lm nhe hnh .................................................................................................................. 168

4.3.2. Lm sc nt hnh ............................................................................................................... 168

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Mc lc hnh v

Hnh 1. S khi ca DSK...................................................................................................... 2

Hnh 2. Hp thoi Project Creation............................................................................................ 4

Hnh 3. Ty chn Compiler Mc Basic ................................................................................. 6

Hnh 4. Ty chn Compiler - Mc Preprocessor ...................................................................... 6

Hnh 5. Ty chn Compiler - Mc Feedback ............................................................................ 7

Hnh 6. Ty chn Compiler - Mc Advanced .......................................................................... 7

Hnh 7. Cc ty chn ca Linker .............................................................................................. 8

Hnh 8. Ca s slider cho php thay i bin gain .................................................................... 9

Hnh 9. Cc ty chn v trong min thi gian ................................................................... 11

Hnh 10. Cc ty chn v trong min tn s ....................................................................... 12

Hnh 11. Kt qu v bng CCS c trong min tn s v trong min thi gian ........................ 12

Hnh 12. Cc ca s lm vic ca Matlab ............................................................................... 13

Hnh 13. Lnh gip (help)................................................................................................... 13

Hnh 14. Giao din ca SPTool .............................................................................................. 16

Hnh 15. Giao din Filter Designer ......................................................................................... 17

Hnh 16. p ng tn s ca b lc thit k ....................................................................... 18

Hnh 17. Cc field ca bs2700 ................................................................................................ 19

Hnh 18. Vector p ng xung ca b lc thit k ............................................................. 19

Hnh 19. p ng tn s ca b lc IIR thit k ................................................................ 20

Hnh 20. Chip AIC23 ............................................................................................................... 23

Hnh 21. nh hng ca tn s ly mu .................................................................................. 24

Hnh 22. Khi phc tn hiu tng t bng b lc .................................................................. 24

Hnh 23. Lng t v m ha .................................................................................................. 24

Hnh 24. Lng t tn hiu ...................................................................................................... 25

Hnh 25. Thc hin b lc FIR dng trc tip. ....................................................................... 41

Hnh 26. Thc hin b lc IIR dng trc tip 1. ..................................................................... 42

Hnh 27. Thc hin b lc IIR dng trc tip 2. ..................................................................... 43

Hnh 28. Thc hin b lc IIR dng trc tip 2 chuyn v. .................................................... 44

Hnh 29. B lc IIR bc 4 vi 2 phn bc 2 dng trc tip 2. ................................................ 44

Hnh 30. Cu trc song song ca b lc IIR. .......................................................................... 45

Hnh 31. p ng tn s ca b lc multiband FIR cn thit k. ........................................... 67

Hnh 32. S cnh bm FFT-2 im. ................................................................................ 92

Hnh 33. Gii thut FFT-8 im phn chia min thi gian. .................................................... 92

Hnh 34. Gii thut FFT-8 im phn chia min tn s.......................................................... 93

Hnh 35. H thng PAM ....................................................................................................... 113

Hnh 36. Gin constellation ca PAM 8 mc .................................................................. 113

Hnh 37. Dng sng trong iu ch PWM ............................................................................ 113

Hnh 38. iu ch PWM trong truyn thng ........................................................................ 114

Hnh 39. C s l thuyt PWM ........................................................................................... 115

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Hnh 40. Cc ty chn v trong min thi gian ............................................................... 124

Hnh 41. B my pht m ..................................................................................................... 133

Hnh 42. Tc ng ca nhiu ................................................................................................ 134

Hnh 43. Dng sng tn hiu ting ni. on 2 v 4 c tn hiu ting ni, on 1, 3, 5 khng c tn hiu ting ni................................................................................................................ 135

Hnh 44. S mt b nhn dng dng ting ni ................................................................ 135

Hnh 45. Phn on ting ni ................................................................................................ 136

Hnh 46. Dng sng ca mt on tn hiu ting ni............................................................ 136

Hnh 47. S b nhn dng gii tnh ................................................................................. 137

Hnh 48. B lc trit nhiu .................................................................................................... 144

Hnh 49. nh 2 chiu ........................................................................................................... 153

Hnh 50. nh ng ................................................................................................................ 153

Hnh 51. nh nh phn .......................................................................................................... 154

Hnh 52. nh mc xm ......................................................................................................... 154

Hnh 53. nh mu ................................................................................................................. 154

Hnh 54. Mt s hm mt xc sut nhiu......................................................................... 156

Hnh 55. nh gc .................................................................................................................. 156

Hnh 56. nh v phn b xc sut vi cc loi nhiu khc nhau 1. ..................................... 157

Hnh 57. nh v phn b xc sut vi cc loi nhiu khc nhau 2. ..................................... 157

Hnh 58. V d v nhiu mui tiu. ....................................................................................... 160

Hnh 59. V d v nhiu tun hon. ...................................................................................... 165

Mc lc cc bng

Bng 1. Bng tra PAM 16 mc .............................................................................................. 120

Bng 2. Bng tra PAM 4 mc ................................................................................................ 121

Bng 3. Bng tra PAM 8 mc ................................................................................................ 121

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GII THIU

Cc b x l s tn hiu c s dng trong rt nhiu ng dng thc t, t truyn thng v iu khin cho n x l ting ni v hnh nh. Hu ht cc thit b gia dng hin nay cng tch hp cc b x l s tn hiu. Chng c s dng trong in thoi di ng, my nh s, HDTV, radio, truyn fax, cc modem, my in, my tr thnh v nhiu thit b khc.

H thng x l s tn hiu c bn bao gm mt b bin i A/D thu nhn tn hiu vo. Sau , dng biu din s ca tn hiu vo s c x l bi mt b x l s tn hiu v tn hiu ra c a qua b bin i D/A. H thng c bn ny cng bao gm mt b lc ng vo chng chng ln ph v mt b lc ng ra khi phc tn hiu x l. Trong cc bi th nghim ny, chng ta c trang b kit TMS320C6713 ca Texas Instruments. Kit TMS320C6713 l mt cng c mnh vi cc phn cng v phn mm cn thit cho x l tn hiu thi gian thc. N l mt h thng x l s tn hiu hon chnh, bao gm mt b x l s du chm ng C6713 v b codec 32-bit stereo TLV320AIC23 (gi tt l AIC23) cho vic xut nhp tn hiu.

Qua cc bi th nghim ny, hi vng cc bn sinh vin s hiu r thm cc khi nim hc trong mn x l s tn hiu, nm c cc bc c bn trong vic thc hin mt ng dng x l s tn hiu ln mt b x l s, nh chip C6713 ca Texas Instruments. Ngoi ra, cc bn sinh vin c th ng dng cc l thuyt x l s tn hiu thc hin cc ng dng x l tn hiu m thanh v hnh nh.

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TI LIU TH NGHIM X L S TN HIU

1

GII THIU KIT DSP V MATLAB

1. MC CH TH NGHIM

- Gii thiu tng quan v kit x l tn hiu kit C6713 DSK.

- Bit c cc bc thc hin gii thut trn kit C6713 DSK.

- Gii thiu tng quan v Matlab v SPTool thit k b lc.

- Gii thiu sinh vin thc thi chng trnh trn Matlab vi cc lnh c bn v x l

m thanh, hnh nh.

2. THIT B TH NGHIM

STT Tn thit b S lng

01 My vi tnh 01

02 Kit C6713 DSK 01

3. GII THIU KIT X L S C6713 DSK (DSP STARTER KIT)

3.1. Kit C6713 DSK

Kit DSK l mt h thng DSP hon chnh. Board DSK bao gm b x l s du chm ng C6713 v b codec 32 bit stereo TLV320AIC23 (AIC23) xut nhp. B codec onboard AIC23 s dng k thut sigma delta bin i A/D v D/A. N c kt ni vi mt ng h h thng 12 MHz. Tn s ly mu c th thay i t 8 n 96 KHz.

Board DSK bao gm 16MB SDRAM v 256kB Flash memory. Bn jack cm trn boad cho php xut nhp: MIC IN (microphone input), LINE IN (line input), LINE OUT (line output) v HEADPHONE (headphone output). Trng thi ca 4 dip switch trn DSK c th c c t chng trnh. DSK hot ng tn s 225 MHz. Trn board DSK cng bao gm cc n p cung cp 1.26V cho nhn C6713 v 3.3V cho b nh v cc ngoi vi.

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B x l TMS320C6713 da trn kin trc VLIW (very-long-instruction-word), ph hp cho cc gii thut nng v tnh ton s. B nh chng trnh ni c t chc mi chu k c th np 8 lnh (instruction), mi instruction di 32 bit.

Cc b x l C67xx (v d C6701, C6711 v C6713) thuc v h cc b x l C6x du chm ng, trong khi C62xx v C64xx thuc v h cc b x l C6x du chm tnh. C6713 c th x l c du chm ng v du chm tnh.

Hnh 1. S khi ca DSK

3.2. Code Composer Studio (CCS)

CCS l mt mi trng pht trin tch hp (IDE). CCS cung cp cc cng c sinh m, nh mt b bin dch C, mt chng trnh assembler v mt chng trnh linker. N c kh nng ha v h tr real-time debug. N cung cp mt cng c phn mm thun tin cho vic xy dng v sa li chng trnh.

Trnh dch C s dch chng trnh ngun vit bng C (tp tin c kiu .c) to thnh mt tp tin ngun assembly (kiu .asm). Trnh assembler s to ra cc tp tin i tng ngn ng my (.obj) t cc tp tin .asm. Trnh linker s kt hp cc tp tin i tng v cc th vic i tng to ra mt tp tin thc thi vi kiu .out. Tp tin thc thi ny c th c np v chy trc tip trn b x l C6713.

to mt project, ngi dng c th thm vo cc tp tin ph hp. Cc ty chn v compiler/linker c th xc nh d dng. Mt s tnh nng debug c sn, nh t cc breakpoint v xem cc bin; xem b nh, cc thanh ghi v trn C vi assembly code; cc kt qu ha; v theo di thi gian thc thi.

Chng ta s lm vic vi mt vi kiu tp tin khc nhau, bao gm:

1. file.pjt: to v xy dng mt project c tn l file

2. file.c: chng trnh ngun vit bng C

3. file.asm: chng trnh ngun bng ngn ng assembly, c to bi ngi dng hoc bi b dch C.

4. file.h: tp tin header

5. file.lib: tp tin th vin

6. file.cmd: tp tin lnh ca linker, nh x cc section vo b nh

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7. file.obj: tp tin i tng c to ra bi assembler

8. file.out: tp tin thc thi c to ra bi linker np v chy trn b x l C6713

3.2.1. Cc tp tin h tr

Cc tp tin h tr sau c cha trong folder C:\CCStudio_v3.1\myprojects\source\support (tr cc tp tin th vin) c s dng trong hu ht cc bi th nghim.

1. C6713dskinit.c: cha cc hm khi ng DSK, codec, cc cng ni tip v xut nhp. Tp tin ny khng c bao gm vi CCS.

2. C6713dskinit.h: tp tin header cha cc prototype ca cc hm.

3. C6713dsk.cmd: Tp tin lnh linker. Tp tin ny c th c sa i khi s dng b nh ngoi thay cho b nh trong.

4. vectors_intr.asm: mt tp tin vector bao gm trong CCS c sa i qun l ngt. C 12 ngt, t INT4 n INT15, v ngt 11 c chn trong tp tin ny. Chng c dng cho cc chng trnh c s dng ngt.

5. vectors_poll.asm: tp tin vector cho cc chng trnh hi vng (polling)

6. rts6700.lib, dsk6713bsl.lib, csl6713.lib: Tp tin th vin h tr run time, board v chip. Cc tp tin ny c cung cp vi CCS v c cha trong cc folder C6000\cgtools\lib, C6000\dsk6713\lib v C6000\csl\lib mt cch tng ng. (Th mc C6000 nm trong th mc ci t ca CCS, mc nh l C:\CCStudio_v3.1\)

3.2.2. Cc v d lp trnh trn DSK

Sau y l mt s v d lp trnh minh ha cho mt s c tnh ca CCS v board DSK. Mc tiu chnh l lm quen vi cc cng c phn mm v phn cng.

V d 1: To tn hiu dng 8 im vi iu khin DIP Switch (sine8_LED)

V d ny to ra mt tn hiu hnh sine bng phng php tra bng. Quan trng hn, n minh ha vi c tnh ca CCS trong hiu chnh, xy dng mt project, s dng cc cng c sinh m v chy mt chng trnh trn b x l C6713. Chng trnh ngun sine8_LED.c thc hin vic to sng sine c ni dung nh di y.

//Sine8_LED.c Sine generation with DIP switch control

#include "dsk6713_aic23.h" //support file for codec,DSK

Uint32 fs = DSK6713_AIC23_FREQ_8KHZ; //set sampling rate

short loop = 0; //table index

short gain = 10; //gain factor

short sine_table[8]={0,707,1000,707,0,-707,-1000,-707};//sine values

void main()

{

comm_poll(); //init DSK, codec, McBSP

DSK6713_LED_init(); //init LED from BSL

DSK6713_DIP_init(); //init DIP from BSL

while(1) //infinite loop

{

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if(DSK6713_DIP_get(0)==0) //=0 if switch #0 pressed

{

DSK6713_LED_on(0); //turn LED #0 ON

output_sample(sine_table[loop]*gain);//output every Ts (SW0 on)

if (++loop > 7) loop = 0; //check for end of table

}

else DSK6713_LED_off(0); //LED #0 off

} //end of while (1)

}

Gii thch chng trnh

Trong chng trnh ny, mt bng sine_table c to ra v cha 8 im th hin gi tr ca sin(t) ti t = 0, 45, 90, 135, 180, 225, 270 v 315 (t l 1000). Trong hm main(), mt hm khc, comm_poll, c gi. Hm ny c cha trong tp tin c6713dskinit.c. N khi ng DSK, b codec AIC onboard v cc cng ni tip trn b x l C6713.

Lnh while(1) trong hm main to mt vng lp v tn. Khi dip switch 0 c nhn, LED 0 c bt ln v tn hiu sine c to ra. Ngc li, hm DSK6713_DIP_get(0) s l false v LED 0 s tt.

Hm output_sample, cha trong tp tin h tr C6713dskinit.c, c gi xut gi tr d liu u tin trong bng sine_table[0] = 0. Ch s lp loop s c tng dn cho n ht bng v tr li gi tr zero.

Mi chu k ly mu Ts = 1/Fs = 1/8000 = 0.125ms, gi tr ca dip switch 0 c kim tra v mt gi tr tip theo trong bng sine_table (nhn vi t l gain) c xut ra. Trong mt chu k tn hiu, 8 gi tr d liu ( cch nhau 0.125ms) c xut ra to mt tn hiu sine. Chu

k ca tn hiu sine thu c l T = 8(0.125ms) = 1ms ng vi tn s f = 1/T = 1 kHz.

To project

Phn ny s minh ha cch to mt project mi, thm cc tp tin cn thit bin dch project sine8_LED.

1. Trong CCS, chn Project New. Trong hp thoi to Project, nhp tn project l sine8_LED, chn Project Type l Executable (.out) v Target l TMSC67xx.

Hnh 2. Hp thoi Project Creation

CCS s t to ra mt th mc tn l sine8_LED trong th mc C:\CCStudio_v3.1\myprojects.

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2. Sau khi to project, cn chp cc tp tin cn thit vo trong th mc sine8_LED va to trc khi thm cc tp tin ny vo project.

a. Chp cc tp tin sine8_LED.c v gain.gel t th mc myprojects\source\project_1 vo trong th mc sine8_LED trn. Tp tin sine8_LED.c chnh l tp tin ngun chnh c vit bng C trn. Tp tin gain.gel c vit bng mt ngn ng thng dch gi l GEL (General Extension Language), tp tin ny s to ra mt giao din c thanh trt (slide) cho php thay i bin gain trong chng trnh chnh khi ang chy chng trnh trn kit.

b. Chp cc tp tin h tr: c6713dskinit.h, c6713dskinit.c, vectors_poll.asm v c6713dsk.cmd trong myprojects\source\support vo trong th mc sine8_LED. Do chng trnh ny s dng cch lp trnh hi vng (polling) nn ta s dng tp tin h tr vectors_poll.asm. Trong trng hp lp trnh c ngt, ta s s dng tp tin vectors_intr.asm.

c. Cui cng, chp cc tp tin dsk6713.h v dsk6713_aic23.h trong C6000\dsk6713\include vo trong th mc sine8_LED.

3. Sau khi chun b xong cc tp tin cn thit, tr v CCS thm cc tp tin vo project. thm tp tin vo project, chn Project Add Files to Project. Trong hp thoi xut hin, vo th mc sine8_LED trn.

a. Chn kiu tp tin (File of Types) l C Source Files v chn cc tp tin C6713dskinit.c v sine8_LED.c ri nhn nt Open thm chng vo project.

b. Chn kiu tp tin l ASM Source Files v thm tp tin vectors_poll.asm vo project.

c. Chn kiu tp tin l Linker Command File v thm tp tin c6713dsk.cmd vo project.

d. Chn kiu tp tin l Object and Library Files thm cc tp tin th vin vo project. Thm tp tin rts6700.lib (h tr kin trc C67x) nm C6000\cgtools\lib vo project. Tng t, thm tp tin dsk6713bsl.lib (nm C6000\dsk6713\lib) v tp tin csl6713.lib (nm C6000\csl\lib) vo project.

e. Chn Project Scan All File Dependencies CCS t thm vo cc tp tin header.

Sau khi thc hin cc bc trn, ca s Project View s hin th cc tp tin c thm vo Project.

Xc nh cc ty chn bin dch chng trnh

bc ny, cc ty chn CCS dch chng trnh ngun thnh tp tin thc thi s c thit lp.

Cc ty chn ca Compiler

1. Trong CCS, chn Project Build Options. Trong ca s xut hin, chn th Compiler.

2. Chn mc Basic (trong Category), v t cc ty chn nh sau: (xem hnh 10)

a. Target Version: C671x {-mv6710}

b. Generate Debug Info: Full Symbolic Debug

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c. Opt Speed vs. Size: Speed most Critical

d. Opt Level and Program Level Opt. : None

Hnh 3. Ty chn Compiler Mc Basic

3. Chn mc Preprocessor v nhp vo Pre-Define Symbol (-d) l CHIP_6713

Hnh 4. Ty chn Compiler - Mc Preprocessor

4. Chn mc Feedback v chn Interlisting l OPT/C and ASM {-s}

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Hnh 5. Ty chn Compiler - Mc Feedback

5. Chn mc Advanced v chn Memory Models l Far (--mem_model:data=far)

Hnh 6. Ty chn Compiler - Mc Advanced

Cc ty chn ca Linker

1. Trong ca s Build Options, chn th Linker t cc ty chn ca Linker.

2. Mc nh CCS Output Filename cng tn vi tn project l sine8_LED.out. Tm thi vn gi nguyn nh vy.

3. Chn Autoinit Model l Run-time Autoinitialization.

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Hnh 7. Cc ty chn ca Linker

Dch v chy chng trnh

Sau khi thit lp cc ty chn ph hp cho Compiler v Linker, chng ta hy tin hnh bin dch chng trnh v np ln trn kit chy.

1. Chn Project Rebuild All hoc nhn nt c hnh 3 mi tn xung trn toolbar. CCS s dch tt c cc tp tin C v Assembly. Cc tp tin i tng to ra c lin kt vi cc tp tin th vin. Cui cng, CCS to ra mt tp tin thc thi sine8_LED.out c th np ln kit chy.

2. Chn File Load Program, m th mc Debug trong th mc sine8_LED, chn tp tin sine8_LED.out np n ln trn kit. Sau , chn Debug Run chy chng trnh.

3. Nh gii thch trn, khi DIP Switch 0 v tr ON, chng trnh s bt sng LED 0 v xut ra tn hiu sine vi tn s 1KHz. quan st kt qu ca chng trnh, c th thc hin theo mt trong cc cch nh sau:

a. Dng headphone v cm vo ng ra HEADPHONE trn kit nghe m thanh.

b. Quan st dng sng sine trn my dao ng k (oscilloscope): kt ni oscilloscope vi ng ra LINE OUT ca kit.

c. Trong my tnh phng th nghim c sn phn mm m phng Oscilloscope c tn l DSP_Tool. Phn mm ny s c d liu t soundcard ca my tnh v hin th. s dng chng trnh ny, s dng cp Audio (c cung cp) kt ni ng ra LINE OUT trn DSK vi ng vo LINE IN trn Soundcard ca my tnh. Trong DSP_Tool, chn File Oscilloscope hin th giao din Oscilloscope ri chn File Start get real data from soundcard bt u c d liu vo. Ngoi ra, cng c th hin th ph

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bng cch chn File Spectrum Analyzer. (Ch cn cu hnh soundcard nhn d liu vo t ng Line In)

Ca s Watch window

Ca s Watch Window cho php thay i gi tr ca mt thng s hoc theo di mt bin. Trong khi chng trnh ang chy v DIP Switch 0 ang c nhn. (Lu dng ch DSP RUNNING trn thanh Status ca CCS).

1. Chn View Quick Watch window. Thng ca s ny hin th phn bn di ca CCS. Nhp gain v nhn Add to Watch. Gi tr gain bng 10 ( c t trong chng trnh) s xut hin trong ca s Watch.

2. Thay i gain t 10 thnh 30 trong ca s Watch ri nhn Enter. Dng sng quan st s thay i khi bin gain thay i gi tr.

S dng tp tin gain.gel

Trong phn trn chng ta cp n tp tin gain.gel. Tp tin ny to mt giao din cho php thay i bin gain mt cch tng tc khi chng trnh ang chy.

1. Trc ht, cn phi np tp tin ny vo bng cch chn File Load GEL v m tp tin gain.gel. Nhn p chut ln tp tin ny trong ca s Project View xem ni dung ca n.

/*gain.gel Create slider and vary amplitude (gain) of sinewave*/

menuitem "Sine Gain"

slider Gain(10,35,5,1,gain_parameter) /*incr by 5,up to 35*/

{

gain = gain_parameter; /*vary gain of sine*/

}

Ni dung ca tp tin gain.gel nh trn. Trong , hm slider Gain c to ra hin th thanh trt. Thanh trt ny bt u t gi tr 10 v kt thc gi tr 35 v mi mc tng l 5 n v.

2. Chn GEL Sinde Gain Gain, ca s sau s xut hin cho php thay i gi tr ca bin gain.

Hnh 8. Ca s slider cho php thay i bin gain

3. Nhn nt mi tn hng ln tng gain t 10 n 15 v quan st dng sng sine to ra thy s thay i.

Thay i tn s ca tn hiu sine to ra

Tn s ca tn hiu sine to ra c th thay i bng mt trong cc cch sau.

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1. Thay i tn s ly mu. Trong tp tin ngun trn, tn s ly mu fs c gn gi tr l DSK6713_AIC23_FREQ_8KHZ. Gi tr ny l 1 hng s nguyn c nh ngha sn. B codec AIC h tr cc tn s ly mu 8, 16, 24, 32, 44.1, 48 v 96kHz. V d, c tn hiu sine ra c tn s l 2kHz, cn tng tn s ly mu ln 16kHz bng cch t fs=DSK6713_AIC23_FREQ_16KHZ.

2. Thay i s im trong bng tra, v d cn 4 im thay v 8 im v d, {0, 1000, 0, -1000}. Khi cn thay i kch thc ca mng sine_table v gi tr bin loop. Hy chng minh rng tn s to ra l f = fs/(s im).

Hai thanh trt c th c s dng va thay i gain, va thay i tn s. Cc tn s tn hiu khc nhau c th to ra bng cch thay i bin loop trong chng trnh (v d nh nhy cch mt im ly mt im).

Lu rng vi chng trnh trn sng sine ch c to ra khi DIP Switch 0 c nhn. s dng mt DIP Switch khc, v d DIP Switch 3, trong chng trnh phi s dng cc hm DSK6713_DIP_get(3), DSK6713_LED_on(3) v DSK6713_LED_off(3).

V d 2: To tn hiu sine v v vi CCS

V d ny cng to ra mt tn hiu sine vi 8 im nh trong v d 1 nhng n minh ha kh nng v dng sng trong min thi gian v min tn s ca CCS. Chng trnh chnh sine8_buf.c c ni dung nh sau:

//sine8_buf Sine generation. Output buffer plotted within CCS

#include "dsk6713_aic23.h" //codec-DSK support file

Uint32 fs=DSK6713_AIC23_FREQ_8KHZ; //set sampling rate

int loop = 0; //table index

short gain = 10; //gain factor

short sine_table[8]={0,707,1000,707,0,-707,-1000,-707};

short out_buffer[256]; //output buffer

const short BUFFERLENGTH = 256; //size of output buffer

int i = 0; //for buffer count

interrupt void c_int11() //interrupt service routine

{

output_sample(sine_table[loop]*gain); //output sine values

out_buffer[i] = sine_table[loop]*gain; //output to buffer

i++; //increment buffer count

if(i==BUFFERLENGTH) i=0; //if @ bottom reinit count

if (++loop > 7) loop = 0; //check for end of table

return; //return from interrupt

}

void main()

{

comm_intr(); //init DSK, codec, McBSP

while(1); //infinite loop

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}

Trong chng trnh ny, mt vng m out_buffer c kch thc 256 c s dng lu li cc d liu xut ra.

Trong hm main, comm_intr c gi. Hm ny nm trong c6713dskinit.c h tr chng trnh c dng ngt. Pht biu while(1) trong hm main to mt vng lp v hn ch ngt xy ra. Khi c xung ly mu, ngt 11 xy ra v trnh phc v ngt (ISR interrupt service routine) c_int11 c gi. a ch ca ISR ny c xc nh trong tp tin vectors_intr.asm vi mt ch dn r nhnh n a ch ny, s dng vector ngt INT11.

Trong ISR ny, hm output_sample, cha trong tp tin c6713dskinit.c, c gi xut ra d liu u tin trong sine_table. Ch s loop c tng cho n ht bng ri lp li t 0. Mt b m ra c to gi 256 (xc nh bi BUFFERLENGTH) mu tn hiu sine xut ra.

Xy dng chng trnh

Hy to project sine8_buf.pjt v thm cc tp tin cn thit nh trong v d 1. Lu rng chng trnh ny s dng ngt nn tp tin vectors_intr.asm c s dng thay cho tp tin vectors_polls.asm. Tp tin sine8_buf.c c cha trong th mc C:\CCStudio_v1.3\myprojects\source\project_2.

Xc lp cc ty chn nh trong v d 1 v dch chng trnh. Np v chy chng trnh trn kit v kim tra rng c mt sng sine 1KHz c to ra.

V vi CCS

B m ra c cp nht lin tc mi 256 im. Sau y CCS s c s dng v d liu ra hin ti cha trong b m out_buffer.

1. Chn View Graph Time/Frequency. Thay i cc ty chn trong ca s Graph Property Dialog nh sau v trong min thi gian. a ch bt u ca b m chnh l tn mng out_buffer c nhp vo Start Address. Cc ty chn khc c th nh mc nh.

Hnh 9. Cc ty chn v trong min thi gian

2. v trong min tn s, chn cc ty chn nh trong hnh sau. Chn bc ca FFT (FFT Order ) sao cho FFT Framesize = 2

order.

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Hnh 10. Cc ty chn v trong min tn s

Kt qu v c th hin trn hnh sau:

Hnh 11. Kt qu v bng CCS c trong min tn s v trong min thi gian

4. GII THIU MATLAB V CNG C SPTOOL

4.1. Matlab

Matlab (Matrix Laboratory) l mi trng tnh ton a ng dng, c tnh ton thc hin nhanh cc php ton ma trn. Matlab h tr nhiu hm phc v cho nhiu lnh vc khc nhau. Matlab cho php thc hin d dng cc tnh ton s v ha.

Khi khi ng Matlab, giao din lm vic (command window) s xut hin nh hnh:,

- Ca s lnh (command window): thc thi cc lnh.

- Khng gian bin (workspace): hin th cc bin c nh ngha.

- Cc lnh thc hin (command history): hin th cc lnh s dng.

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Hnh 12. Cc ca s lm vic ca Matlab

hiu r cch s dng mt hm, c th s dng lnh >>help v hm tng ng.

Hnh 13. Lnh gip (help)

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Matlab c th thc thi cc lnh ca s lnh t du nhc ca ca s lnh.

V d: Cch lnh v th tn hiu sin

>> t = 0:0.01:2; % cho t thay gi tr t 0 n 2, mi gi tr cach nhau 0.01

>> x = sin(2*pi*t); % tnh gi tr hm (2 pi t) cho tng gi tr t

>> plot(t,x,b); % V th ng mu xanh

>> xlabel(t in sec); ylabel(x(t)); % t tn trc x v trc y

>> title(Plot of sin(2\pi t)); % Tiu th

V d: c xut tn hiu m thanh

>> [road,fs]=wavread('road.wav'); % c file m thanh, mng road cha d liu m thanh stereo, fs l tn s ly mu

>> left=road(:,1); % Ly d liu knh tri

>> right=road(:,2); % Ly d liu knh phi

% V th 2000 mu tn hiu knh tri

>> time=(1/fs)*2000; % Thi gian 2000 mu

>> t=linspace(0,time,2000); % Chia thi gian t 0 n time c 2000 mu

>>plot(t,left(1:2000)) % V dng sng

>> xlabel('time (sec)'); % Tn trc x

>>ylabel('relative signal strength') % Tn trc y

>>grid on % to li trn th

% To hiu ng ting di (echo)

>>Lenleft=length(left); % Tnh s mu ca tn hiu

>> delay=1000; % Cho s mu tr mong mun

>>a=0.5; % Suy hao tn hiu tr

>>echo=left+a*[zeros(1, delay) left(1:end-delay)']';

>>soundsc(echo,fs); % Nghe tn hiu echo

>>wavwrite(echo, fs, 'roadecho.wav'); % Lu tn hiu sau x l thnh file

V d: c v xut file nh

% c nh

>>img = imread('apple.jpg');

>>dim = size(img);

% Hin th nh

>>figure;

>>imshow(img); % image(img)

% lu file nh

>>imwrite(img, 'output.bmp', 'bmp');

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Ngoi ra, cc hm thc hoc chng trnh con c th thc hin qua file. m

V d: To hm m cng hai tn hiu sin c tn s v bin khc nhau

function y=sumsin(A1, f1, A2, f2, Time, fs)

% Cong 2 tin hieu sin co bien do va tan so khac nhau

% Input

% A1, f1: bien do va tan so tin hieu sin 1

% A2, f2: bien do va tan so tin hieu sin 2

% Time (giay) khoang thoi gian can tinh

% fs (Hz): tan so lay mau

% Output: y(t)=A1*sin(2*pi*f1*t)+A2*sin(2*pi*f2*t)

% Vi du: y=sumsin(1, 2, 2, 4, 1, 50)

N=round(Time*fs) % So mau

n=0:N;

x1=A1*sin(2*pi*(f1/fs)*n);

x2=A2*sin(2*pi*(f2/fs)*n);

y=x1+x2;

figure;

subplot(3,1,1);

stem(n/fs, x1);

xlabel('time');

ylabel('x1(t)');

subplot(3,1,2);

stem(n/fs, x2);

xlabel('time');

ylabel('x2(t)');

subplot(3,1, 3);

stem(n/fs, y);

xlabel('time');

ylabel('y(t)=x1(t)+x2(t)');

end

lu chng trnh con vi tn phi cng tn vi tn hm, v d trn ta lu li sumsin.m. Hm sumsin() khi c th c gi t chng trnh khc hoc c th thc thi t ca s lnh, v d

>> y=sumsin(1, 2, 2, 4, 1, 50)

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4.2. Thit k b lc s bng cng c SPTool

SPTool l mt cng c c giao din tng tc dng cho x l s tn hiu. Cng c ny c th c s dng phn tch tn hiu, thit k cc b lc, phn tch cc b lc, lc tn hiu v phn tch ph ca tn hiu.

khi ng SPTool, t du nhc lnh ca MATLAB, nhp lnh

>> sptool

Khi , giao din ca SPTool s xut hin nh sau:

Hnh 14. Giao din ca SPTool

Khi mi m SPTool, n cha mt tp hp cc tn hiu, b lc v ph mc nh. Trn giao din ca SPTool, c 3 ct: Signals, Filters v Spectra. Di mi ct c cc nt s dng cho ct . Ct Signals hin th cc tn hiu, ct Filters hin th cc b lc v ct Spectra hin th cc ph trong workspace (vng lm vic) ca SPTool.

Cc tn hiu, b lc hoc ph trong workspace ca MATLAB c th c a vo SPTool bng lnh Import trong menu File ca SPTool. Cc tn hiu, b lc hoc ph c to ra hoc c import vo SPTool tn ti di dng cc cu trc ca MATLAB. lu li cc tn hiu, b lc v ph to ra hoc chnh sa trong SPTool, s dng lnh Export trong menu File, chng cng s c lu li di dng cc cu trc MATLAB.

bt u thit k mt b lc mi, cc bn hy nhn vo nt New ngay di ct Filter. Khi , giao din Filter Designer dng thit k b lc nh sau s xut hin.

Filter Designer cung cp mt mi trng ha tng tc thit k cc b lc s IIR hoc FIR da trn cc tiu chun do ngi dng xc nh.

- Cc loi b lc c th thit k: Thng thp, thng cao, thng di, chn di.

- Cc phng php thit k b lc FIR: Equiripple, Least squares, Window

- Cc phng php thit k b lc IIR: Butterworth, Chebyshev loi I, Chebyshev loi II, Elliptic.

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Hnh 15. Giao din Filter Designer

V d 1: Thit k mt b lc FIR chn di bng SPTool

B lc, c thit k bng phng php ca s Kaiser, vi cc thng s sau:

Chiu di ca p ng xung: N = 89 (MATLAB hin th bc b lc bng 88)

Tn s trung tm: 2700 Hz

Tn s ct: 2500 Hz v 2900 Hz

Gi tr ca = 4

Tn s ly mu 8000 Hz

Cc bc thit k nh sau:

1. Khi ng SPTool. Di ct Filters, nhn nt New m ca s Filter Designer.

2. Trong giao din ca Filter Designer:

a. Trong text box Filter: Tn b lc c t t ( y l filt1). Tn ny c th thay i sau ny.

b. Nhp cc thng s thit k vo:

i. Sampling Frequency = 8000

ii. Algorithm: Kaiser Window FIR

iii. B chn check box Minimum Order. (nu chn th s thit k b lc c bc ti thiu).

iv. Filter Order = 88, Type = Bandstop, Fc1 = 2500, Fc2 = 2900, Beta = 4

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c. Nhn Apply. Khi p ng tn s ca b lc thit k s c hin th.

Hnh 16. p ng tn s ca b lc thit k

3. Tr v ca s SPTool, trong ct Filters s xut hin thm mt dng filt1 [design]. y chnh l b lc va thit k. Sau ny, nu mun sa i thit k, chn li tn b lc v nhn nt Edit pha di. d nh, ta s thay i tn b lc trn thnh bs2700 bng cch chn Edit Namefilt1 [design]. Trong ca s mi xut hin, nhp tn mi.

Khi thit k mt b lc FIR nh trn, kt qu m ta cn nhn c sau khi thit k l cc gi tr ca vector p ng xung h ca b lc thit k. ly cc gi tr ca vector p ng xung, ta thc hin nh sau:

1. T ca s SPTool, chn File Export Trong Export list xut hin, chn Filter: bs2700 [design] ri nhn nt Export to workspace

2. ng ca s SPTool li. Mt thng bo xut hin hi c mun lu li phin lm vic hin ti hay khng. Nu mun lu li, chn Save.

3. M ca s Workspace ca MATLAB, ta s thy trong workspace s xut hin bin mi l bs2700. y chnh l b lc m ta thit k trong SPTool v xut ra workspace ca MATLAB. Bin ny c lu di dng mt cu trc m t b lc thit k. Nhn p chut vo tn bin bs2700 trong workspace, ta s thy c cc field ca cu trc ny nh sau:

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Hnh 17. Cc field ca bs2700

4. Trong cc field ny, field tf th hin hm truyn ca b lc. Field ny cng l mt cu trc gm 2 field: tf.num v tf.den th hin tng ng cc h s ca a thc t s v a thc mu s. i vi b lc FIR, hm truyn ch c t s v cc h s ca t s chnh l p ng xung ca b lc. Do , vi b lc trn, cc gi tr ca vector p ng xung c lu trong bs2700.tf.num. Trong ca s Array Editor trn, ln lt nhn p vo field tf ri nhn p vo num, ta s thy cc h s p ng xung ca b lc. gn cc h s ny vo mt vector h, trong MATLAB c th dng lnh sau:

>> h = bs2700.tf.num

Hnh 18. Vector p ng xung ca b lc thit k

Cc gi tr thu c ca vector p ng xung s c s dng thc hin b lc s ln trn kit DSP.

V d 2: Thit k b lc IIR chn di bng SPTool

S dng phng php Elliptic thit k mt b lc IIR chn di bc 10, tn s trung tm 1750Hz. Ch rng MATLAB hin th bc b lc l 5, biu din s phn bc 2 ca b lc. (iu ny ng vi cc b lc IIR thng di v chn di)

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Cc thng s ca b lc ny nh sau.

Tn s ct: 1700 Hz v 1800 Hz

gn di thng v di chn tng ng l 1 dB v 60 dB

Tn s ly mu: 8000 Hz

Thc hin tng t nh v d trn, lu b lc thit k vi tn bs1750 v xut ra workspace. Trong workspace s c mt cu trc tn l bs1750. Cc h s t s v mu s ca hm truyn c lu tng ng trong cc bin bs1750.tf.num v bs1750.tf.den.

Hnh 19. p ng tn s ca b lc IIR thit k

Dng cc zero ca mt hm truyn H(z) nh sau:

m

n

pzpzpz

zzzzzzkzH

...

...)(

21

21

Hm truyn trn c th c vit li nh sau:

L

k kk

kkkL

k

kzaza

zbzbbgzHgzH

12

2

1

1

2

2

1

10

1 1)(

Vi L l s nguyn gn nht ln hn cc i ca n/2 v m/2.

Trong MATLAB, cc phn bc 2 ca H(z) c lu trong 1 ma trn nh sau:

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LLLLL aabbb

aabbb

aabbb

sos

21210

2212221202

2111211101

1

1

1

T cc h s t v mu trn, ta s chuyn thnh dng cc phn bc hai bng cc lnh sau:

>> [z,p,k] = tf2zp(bs1750.tf.num, bs1750.tf.den)

>> sos = zp2sos(z,p,k)

Cc phn t ca ma trn sos ny s c s dng thc hin b lc IIR ny ln kit DSP.

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LY MU V LNG T HA TRN KIT C6713 DSK

H v tn SV bo co 1: . MSSV: .......




Nhm lp: ... Tiu nhm: ...... Ngy th nghim: ...

im nh gi CBGD nhn xt v k tn

Chun b

l thuyt

Bo co v

kt qu TN Kim tra Kt qu

1. MC CH TH NGHIM

- Hiu r qu trnh ly mu v lng t ha tn hiu trong b ADC.

- H thng li cc l thuyt hc.

- Gip sinh vin c ci nhn trc quan v hin tng alising khi iu kin ly mu khng tha.

- Gip sinh vin hiu c nh hng ca vic tng/gim s bit m ha mt mu tn hiu.

2

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2. THIT B TH NGHIM

STT Tn thit b S lng

01 My vi tnh 01

02 Kit C6713 DSK 01

03 My pht sng 01

04 B dy ni tn hiu 01

3. C S L THUYT

3.1. Gii thiu

X l tn hiu s c rt nhiu u im so vi x l cc tn hiu tng t. Mt h thng x l s tn hiu bao gm b ADC, b x l trung tm v b DAC. Tn hiu tng t khi i vo h thng, i qua b ADC s c ly mu v m ha thnh chui bit nh phn. Chui bit ny i qua b x l trung tm v sau i qua b DAC. B DAC s bin chui bit tr thnh li cc tn hiu tng t i ra ngoi.

KIT C6713 DSK s dng chip AIC23 ly mu v m ha tn hiu. Tn hiu tng t c a vo AIC23 v ly mu vi tn s 8KHz. trnh hin tng aliasing, chip AIC23 c thm mt b tin lc vi tn s 4KHz m bo tn hiu vo c tn s ln nht l 4KHz. Cc mu sau c lng t ha v m ha thnh chui 8bit. Do b x l trung tm 6713DSP hot ng vi cc word 32 bit nn chui bit m ha ca cc mu c thm 24 s 0 vo sau cng tr thnh cc word 32 bit.

Hnh 20. Chip AIC23

3.2. Ly mu tn hiu

Ly mu l qu trnh bin i tn hiu lin tc v mt thi gian thnh mt tn hiu ri rc v mt thi gian. Tn hiu x(t) sau khi ly mu s tr thnh tn hiu ri rc v mt thi gian x(n) = x(nT), vi T l chu k ly mu. 02 tn hiu lin tc khc nhau, nhng khi c ly mu vi tn s fs, ta c x1(n) = x2(n), hin tng ny c gi l aliasing, v 2 tn hiu c gi l alias vi nhau. trnh hin tng ny, tn hiu phi tha iu kin ly mu.

nh l ly mu: Tn hiu c ly mu phi c bng thng gii hn, tn s ly mu thp nht ln hn 2 ln tn s ln nht ca tn hiu fs >= 2fmax.

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Tn hiu sau khi ly mu c ph l ph ca tn hiu ban u c lp li sau nhng khong fs. Hin tng aliasing xy ra do s chng lp ca ph tn hiu sau nhng khong fs.

Hnh 21. nh hng ca tn s ly mu

Tn hiu sau khi ly mu c phc hi l tng. B phc hi l tng l mt b lc thng thp vi tn s ct bng ti tn s Nyquist fs/2.

Hnh 22. Khi phc tn hiu tng t bng b lc

Nu tn hiu ban u c tn s f nm trong khong Nyquist, tn hiu sau khi ly mu vi tn s fs v phc hi l tng s c tn s bng vi tn s tn hiu ban u. Ngc li, tn hiu c tn s nm ngoi khong Nyquist sau khi ly mu v phc hi l tng s c tn s fa = f mod(fs). Tn hiu c tn s fa nh th c gi l tn hiu b alias vi tn hiu c tn s f khi ta ly mu vi tn s fs.

3.3. Lng t v m ha

Cc tn hiu sau khi ly mu s c lng t v m ha thnh cch chui B bit.

Hnh 23. Lng t v m ha

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Nu tn hiu c tm ton thang l R, phn gin lng t / 2BQ R .

Hnh 24. Lng t tn hiu

Nu coi qu trnh lng t ha ging nh vic cng thm nhiu lng t v tn hiu, ta c t

s tn hiu trn nhiu s l 6dBSNR B . Nu s bit B m ha cc mu tng ln th t s tn

hiu trn nhiu tng ln, cht lng tn hiu sau khi phc hi s tng ln, qu trnh lng t ha tn hiu t nh hng n tn hiu. Ngc li, nu s bit m ha tn hiu gim i, cht lng tn hiu sau khi phc hi s gim xung do nhiu lng t tng ln, tn hiu sau khi phc hi s b sai dng so vi tn hiu ban u.

4. CHUN B TH NGHIM

1. Mt h thng c tn s ly mu fs = 8KHz. Xc nh tn s ct ca b tin lc l tng khng xy ra hin tng aliasing. Gii thch.

2. Mt tn hiu ( ) 5sin 6x t t (t: ms). Xc nh tn s ly mu thp nht c th phc hi li tn hiu. Tn hiu c ly mu vi tn s 4KHz. Sau tn hiu c phc hi l tng. Xc nh tn hiu sau khi c phc hi l tng. Gii thch ngn gn.

3. Cho mt tn hiu c tm ton thang R = 10V. Xc nh s bit B m ha tn hiu c sai s lng t hiu dng (rms) khng qu 50microV.

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4. Cho mt tn hiu lng cc c tm ton thang l 16V, c m ha thnh 4bit bng phng php rounding. Cc mu tn hiu c gi tr: -7.9, -7.1,- 6.8,- 5.5,-3.1, 0, 1.3, 2.6, 5.8, 6.9.

a. Xc nh chui bit cho cc mu trn nu m ha bng b m offset binary.

b. Lp li cu trn vi b m b bc 2.

5. TIN HNH TH NGHIM

Ly mu tn hiu

Trc ht, hy thc hin theo tng bc v d n gin sau.

V d : Cho tn hiu hnh sin c tn s 3KHz i qua bADC ca AIC32. Tn hiu sau c cho i ngc li b DAC ca AIC32. Quan st tn hiu c hin th trn my tnh.

Trong v d ny tn hiu t my pht sng x(t) sau khi i qua b AIC32 trong Kit C6713DSK s l tn hiu c ly mu x(nT). x(nT) s i qua h thng l vi x l DSP6713. Trong v d ny, tn hiu ng ra ca h thng s ging tn hiu ng vo y(n) = x(nT). Sau y(n) s c a ngc li b DAC ca AIC32 v khi phc li thnh tn hiu y(t). Tn hiu y(t) s c a vo v hin th trn my tnh.

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Chng trnh h thng cho DSP6713 ly tn hiu ng ra l tn hiu ng vo

A. H thng ny c thc hin trn kit bng chng trnh sau (vit bng ngn ng C) B. M project b lc FIR:

1. Trong chng trnh

2. Chn project FIR theo ng dn: C:\Program Files\CCStudio_v3.1\myprojects\FIR\FIR.pjt

3. M chng trnh chnh FIR.c

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Vit li chng trnh chnh ca b lc FIR theo chng trnh sau:

//Fir.c FIR filter. Include coefficient file with length N

#include "coefficients.h" //coefficient file

#include "dsk6713_aic23.h" //codec-dsk support file


int yn = 0; //initialize filter's output

int pulse;

interrupt void c_int11() //ISR

{

yn = input_sample();

output_sample(yn >> 15); //scale output filter sample

return;

}

void main()

{



}

C. Bin dch v chy chng trnh: 1. Chn Project Rebuild All hoc nhn nt c hnh 3 mi tn xung trn

toolbar. CCS s dch tt c cc tp tin C v Assembly. Cc tp tin i tng to ra c lin kt vi cc tp tin th vin. Cui cng, CCS to ra mt tp tin thc thi FIR.out c th np ln kit chy. (Nu chng trnh bin dch b li th kim tra li v sa li, sau bin dch li).

2. Chn Debug Connect hoc bm t hp phm Alt+C kt ni vi kit. 3. Chn File Load Program, m th mc Debug trong th mc FIR, chn tp

tin FIR.out np n ln trn kit. Sau , chn Debug Run chy chng trnh trn kit.

4. Khi cn thay i hay chnh sa chng trnh cho mt v d khc, ta chn Debug Halt ngt kt ni vi kit, ri thc hin li cc bc nh ban u.

nh gi kt qu thc hin

M ngun ca my pht sng. To mt tn hiu hnh sine 3KHz t my pht sng v quan st dng sng ng ra. V li dng sng v ph ca tn hiu ng ra. Nhn xt ngn gn.

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Sau khi thc hin v d trn, sinh vin tip tc thc hin vic thay i tn s ly mu thy r hin tng aliasing khi khng tha mn iu kin ly mu tn hiu.

AIC23 c c nh tn s ly mu v ta ch c th thay i chng trnh trong vi x l DSP6713. AIC c tn s ly mu l 8KHz, vy nn trong 1 giy s c 8000 mu c a ti vi x l DSP6713. Chng ta c th gim tc ly mu xung cn 4KHz bng cch thay v vi x l ly ton b mu, ta s ly mt mu v b 1 mu. Nh vy trong 1 giy, chng ta ch nhn 4000 mu, hay ni cch khc, tc ly mu c thay i xung cn 4KHz.

thc hin iu ny, ta nhn tn hiu ng vo vi mt chui tun hon [1, 0, 1, 0, 1, 0,]. Vic ny c th thc hin trn chng trnh bng dng lnh sau:

yn = pulse * input_sample();

pulse = (pulse==0);

Sinh vin thc hin

Cho tn hiu hnh sin c tn s 3KHz i qua h thng. Tn hiu c ly mu vi tn s 4KHz. Tn hiu sau c i qua b lc thng thp tn s 4KHz. Tn hiu ng ra c tn s bao nhiu?

Quan st v v li dng dng v ph ca tn hiu ng ra. So snh vi trng hp v d khi ta ly mu vi tn s 8KHz. Nhn xt.

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Cho tn hiu xung vung c tn s 0.5KHz i qua h thng. Tn hiu c ly mu vi tn s 8KHz. Tn hiu sau c phc hi l tng. Quan st v v li dng dng v ph ca tn hiu ng ra. Nhn xt v gii thch ngn gn.

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Thay i tn s ly mu cn 4KHz. Quan st v v dng sng v ph tn hiu ng ra. So snh 02 trng hp khi ly mu vi tn s 4KHz v 8KHz ca xung vung tn s 0.5KHz. Nhn xt v gii thch ngn gn.

Lng t ha tn hiu

Mi mu tn hiu c AIC32 m ha v a ti vi x l s c dng chui bit:

[b1, b2, b3, b4, b5, b6, b7, b8, 0, 0] (24 s khng)

Trong bit b1 l MSB v b8 l LSB

Chng ta c th thay i s mc lng t xung thp hn bng cch dch phi ri dch tri chui bit. V d ta c th thay i t 256 mc lng t (tng ng 8bit) xung thnh 128 mc (tng ng 7bit) bng cch b i bit cui cng b8. iu ny c thc hin bng cch dch phi ri dch tri 25bit nh sau:

[b1, b2, b3, b4, b5, b6, b7, b8, 0, 0] => [0, 0,0, b1, b2, b3, b4, b5, b6, b7,] => [b1, b2, b3, b4, b5, b6, b7, 0, 0, 0]

Vic ny c th thc hin trn chng trnh bng dng lnh sau:

yn = (input_sample() >> 25)

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Sinh vin thc hin

1. Cho tn hiu hnh sin c tn s 3KHz i qua h thng. Tn hiu c ly mu vi tn s 8KHz. Mi mu tn hiu c m ha thnh chui 8bit. Tn hiu sau c phc hi l tng. Quan st v v dng sng v ph tn hiu ng ra.

Thc hin vic gim dn s bit m ha xung cn 6, 4, 2, 0 bit. Quan st v v dng sng v ph tn hiu ng ra. Nhn xt.

Trng hp mi mu c m ha bng 6bit.


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- Cho tn hiu xung vung c tn s 3KHz i qua h thng. Tn hiu c ly mu vi tn s 8KHz. Mi mu tn hiu c m ha thnh chui 8bit. Tn hiu sau c phc hi l tng. Quan st v v dng sng v ph tn hiu ng ra.

Thc hin vic gim dn s bit m ha xung cn 6, 4, 2, 0 bit. Quan st v v dng sng v ph tn hiu ng ra. So snh v nhn xt vi trng hp sng sin.


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5. Mt h thng c tn s ly mu fs = 8KHz. Xc nh tn s ct ca b tin lc l tng khng xy ra hin tng aliasing. Gii thch.

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6. Mt tn hiu ( ) 5sin 6x t t (t: ms). Xc nh tn s ly mu thp nht c th phc hi li tn hiu. Tn hiu c ly mu vi tn s 4KHz. Sau tn hiu c phc hi l tng. Xc nh tn hiu sau khi c phc hi l tng. Gii thch ngn gn.

7. Cho mt tn hiu c tm ton thang R = 10V. Xc nh s bit B m ha tn hiu c sai s lng t hiu dng (rms) khng qu 50microV.

8. Cho mt tn hiu lng cc c tm ton thang l 16V, c m ha thnh 4bit bng phng php rounding. Cc mu tn hiu c gi tr: -7.9, -7.1,- 6.8,- 5.5,-3.1, 0, 1.3, 2.6, 5.8, 6.9.

a. Xc nh chui bit cho cc mu trn nu m ha bng b m offset binary.

b. Lp li cu trn vi b m b bc 2.

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B LC FIR/IIR TRN KIT C6713 DSK





Nhm lp: ... Tiu nhm: ...... Ngy th nghim: ...

im nh gi CBGD nhn xt v k tn

Chun b

l thuyt

Bo co v

kt qu TN Kim tra Kt qu

1. MC CH TH NGHIM

- Hiu r cc bc t thit k n hin thc b lc FIR/IIR ln trn mt kit DSP.

- Quan st p ng xung v p ng tn s ca b lc.

- Kim tra c tnh (thng thp, thng cao, thng di, chn di) ca b lc.

- Kho st ng ra ca b lc khi ng vo l tn hiu xung vung.

- H thng li cc l thuyt hc.

3

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2. THIT B TH NGHIM

STT Tn thit b S lng

01 My vi tnh 01

02 Kit C6713 DSK 01

03 My pht sng 01

04 B dy ni tn hiu 01

3. C S L THUYT

Lc l mt trong nhng hot ng x l tn hiu quan trng. Mt b lc tng t hot ng

trn cc tn hiu lin tc v thng c thc hin vi cc linh kin nh khuch i thut

ton, cc in tr v cc t in. Mt b lc s hot ng trn tn hiu thi gian ri rc v c

th thc hin vi mt b x l s tn hiu nh h TMS320C6x. Qu trnh lc bao gm s

dng mt b bin i A/D nhn tn hiu vo, x l cc mu vo ri gi kt qu ra thng

qua mt b bin i D/A.

Cc b lc s c rt nhiu u im so vi cc b lc tng t. Cc u im ny bao gm

tin cy cao hn, chnh xc cao hn v t nhy vi nhit v tui i. Cc c tnh lc

nh tn s trung tm, bng thng v loi b lc c th thay i d dng. Mt s cng c c

sn cho vic thit k v thc hin cc b lc s mt cch nhanh chng trn kit TMS320C6x.

3.1. B lc FIR

B lc FIR nhn qu bc M c p ng xung h = [h0, h1, , hM] (chiu di bng M + 1).

Ng ra ca b lc c xc nh theo cng thc tch chp:

mm

mnhmxmnxmhny )()()()()(

trong x(n) l ng vo ca b lc.

Hm truyn ca b lc c xc nh t bin i Z ca h(n):

M

M

M

n

n zhzhhznhzH

...)()( 1100

trong cc h s ca hm truyn chnh l p ng xung h ca b lc.

B lc FIR c th thit k bng nhiu phng php, trong phng php n gin nht l

phng php ca s.

B lc c th c thc hin bng hai phng php: Phng php x l khi v phng

php x l mu. Vi phng php x l mu, b lc c th c thc hin dng trc tip nh

sau:

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Hnh 25. Thc hin b lc FIR dng trc tip.

Nu t cc bin trng thi:

v0(n) = x(n)

v1(n) = x(n 1)

vM(n) = x(n M)

Ta s c gii thut x l mu ng vi s khi trn nh sau:

Vi mi mu vo x:

v0 = x

M

0k

kk vhy

vM = vM-1

v1 = v0

3.2. B lc IIR

Hy xem xt mt phng trnh I/O tng qut c dng:

)()2()1(

)()2()1()(

)()()(

21

210

0 1

Mnybnybnyb

Nnxanxanxanxa

jnybknxany

M

N

N

k

M

j

jk

Dng phng trnh quy ny biu din mt b lc IIR. Ng ra y(n) thi im y(n) khng

ch ph thuc vo ng vo hin ti x(n) thi im n v cc ng vo trong qu kh x(n 1),

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x(n 2), , x(n N), m cn ph thuc vo cc ng ra trc y(n 1), y(n 2), , y(n

M).

Nu chng ta gi s cc iu kin ban u u bng 0, bin i Z phng trnh trn s cho:

)()()(

)()()()()(

2

2

1

1

2

2

1

10

zYzbzYzbzYzb

zXzazXzazXzazXazY

M

M

N

N

Khi N = M, hm truyn H(z) l

)(

)(

1)(

)()(

2

2

1

1

2

2

1

10

zD

zN

zbzbzb

zazazaa

zX

zYzH

N

N

N

N

trong N(z) v D(z) biu din a thc t s v a thc t s ca hm truyn. Nhn v chia

cho zN, H(z) tr thnh:

N

i i

i

N

NNN

N

NNN

pz

zzC

bzbzbz

azazazazH

12

2

1

1

2

2

1

10)(

y l mt hm truyn vi N zero v N cc. Nu tt c cc h s bj bng 0, hm truyn ny

tr thnh hm truyn ca mt b lc FIR. h thng n nh, tt c cc cc phi nm trong

vng trn n v.

Cc b lc IIR c th c thc hin theo cc cu trc sau:

1. Dng trc tip 1

Hnh 26. Thc hin b lc IIR dng trc tip 1.

Khi thc hin dng ny, mt b lc bc N cn dng 2N khi lm tr.

2. Dng trc tip 2 (Dng chnh tc)

y l mt trong nhng cu trc thng c s dng. N ch cn mt na s khi tr so vi

dng trc tip 1.

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t )(

)()(

zD

zXzU trong D(z) l mu s ca hm truyn b lc IIR.

Khi :

N

N zazazaazU

zUzNzXzD

zNzY

221

10)((

)()()()(

)()(

vi N(z) l t s ca hm truyn.

V:

)1)(()()()( 221

1

N

N zbzbzbzUzDzUzX

Bin i Z ngc ta s c:

)()2()1()()(

)()2()1()()(

210

21

Nnuanuanuanuany

Nnubnubnubnxnu

N

N

Thc hin di dng s khi:

Hnh 27. Thc hin b lc IIR dng trc tip 2.

3. Dng trc tip 2 chuyn v

Dng trc tip 2 chuyn v l mt bin th ca dng trc tip 2 v cn cng s khi tr. Cc

bc sau chuyn mt b lc t dng trc tip 2 sang dng chuyn v:

i. o hng tt c cc nhnh

ii. i u vo vi u ra

iii. V li s sao cho u vo bn tri v u ra bn phi

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Hnh 28. Thc hin b lc IIR dng trc tip 2 chuyn v.

4. Dng cascade cc tng bc 2

Hm truyn trn c th c phn tch thnh tch cc hm truyn bc 1 hoc bc 2 nh sau:

)()()()( 21 zHzHzCHzH r

Cu trc ni tip (cascade) ny c v nh sau:

Hnh 5. Cu trc cascade ca b lc IIR.

Hm truyn ton b c th c biu din bng s ghp cascade cc hm truyn. i vi mi

phn, dng trc tip 2 hoc chuyn v ca n c th c s dng. Hm truyn H(z) di

dng cascade cc hm truyn bc hai c th vit nh sau:

2/

12

2

1

1

2

2

1

10

1)(

N

i ii

iii

zbzb

zazaazH

Hnh sau v mt b lc IIR bc 4 di dng cascade ca hai phn bc 2.

Hnh 29. B lc IIR bc 4 vi 2 phn bc 2 dng trc tip 2.

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5. Dng song song

Hm truyn b lc IIR cng c th c biu din nh sau (bng phng php khai trin

phn s tng phn):

)()()()( 21 zHzHzHCzH r

Cu trc song song ny c th v nh sau:

Hnh 30. Cu trc song song ca b lc IIR.

4. CHUN B L THUYT TH NGHIM

4.1. B lc FIR

Cho mt b lc FIR c p ng xung h = [1; -2; -3; -4].

Cu hi chun b (l thuyt)

1. Xc nh bc b lc?

2. Vit phng trnh sai phn I/O ca b lc?

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3. V s khi thc hin dng trc tip v gii thut x l mu.

4. Vit biu thc hm truyn ca b lc?

5. V p ng bin -tn s v pha-tn s ca b lc?

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6. Xc nh c tnh (thng thp, thng cao, thng di, chn di) ca b lc?

7. Xc nh tn s ct -3dB v dc ca b lc?

4.2. B lc IIR

Cho mt b lc c hm truyn nh sau:

22 25.01

4

25.01

5)(

zzzH

Cu hi chun b (l thuyt)

1. Xc nh bc b lc?

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2. Vit phng trnh sai phn I/O ca b lc?

3. Hy v cch thc hin dng trc tip (direct form) ca b lc.

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4. Hy v cch thc hin dng chnh tc (canonical form) ca b lc.

5. Hy v cch thc hin dng ghp ni tip cc tng bc hai (cascade form) ca b lc.

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6. V p ng bin -tn s v pha-tn s ca b lc?

7. Xc nh c tnh (thng thp, thng cao, thng di, chn di) ca b lc?

8. Xc nh tn s ct -3dB v dc ca b lc?

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Cu hi chun b (th nghim): sinh vin c k tin trnh th nghim tr li.

1. S lng b lc cn phi thc hin trong bi th nghim?

2. Cc phng php thit k b lc FIR/IIR dng MATLAB?

3. Tm tt quy trnh thit k b lc FIR/IIR dng MATLAB?

4. Cc h s p ng xung ca b lc FIR/IIR dng trong chng trnh DSP c lu

trong tp tin no?

5. So snh s khc bit v cch thc biu din ca p ng xung b lc FIR/IIR trong

phn mm MATLAB v C (kit DSP)?

6. Tm tt quy trnh thc hin b lc FIR/IIR trn kit DSP?

7. Nhng thng s cn iu chnh khi quan st p ng xung v p ng tn s ca b

lc dng chng trnh CCS ca kit DSP?

8. Nhng chc nng no ca ngun my pht sng cn iu chnh trong bi th nghim?

Nhng lu cn quan tm khi s dng ngun my pht sng?

9. Tm hiu mt s lnh trong MATLAB lin quan n x l chui h tr chuyn i

kt qu t MATLAB sang C dng cho kit DSP? Vit on chng trnh MATLAB h

tr vic chuyn i ny?

B M

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5. TIN TRNH TH NGHIM

Trong phn th nghim ny c 3 yu cu chnh cn phi thc hin:

1. Thit k b lc: Kt qu ca phn ny l c c p ng xung h(n) ca b lc.

2. Thc hin b lc ln trn kit C6713 DSK: S dng p ng xung thu c t phn thit

k, vit chng trnh thc hin mch lc ln kit. Chng trnh s c tng mu d liu

vo v tin hnh gii thut x l mu tnh ng ra.

3. Kim tra b lc thc hin: Trong phn ny, b lc thc hin trn kit s c kim

tra xem c p ng yu cu t ra hay khng. Chng ta s s dng mt my pht sng

to tn hiu ng vo v quan st tn hiu ng ra ca b lc khi thay i tn hiu ng

vo.

5.1. Cc b lc FIR

5.1.1. B lc FIR chn di

Thit k, thc hin v kho st b lc FIR chn di bng phng php ca s Kaiser vi cc

thng s sau:

Chiu di ca p ng xung: N = 63 (MATLAB hin th bc b lc bng 62)

Tn s trung tm: 2700 Hz

Tn s ct: 2500 Hz v 2900 Hz

Gi tr ca = 4

Tn s ly mu 8000 Hz

Thit k b lc dng MATLAB

1. Khi ng SPTool. Di ct Filters, nhn nt New m ca s Filter Designer.

2. Trong giao din ca Filter Designer:

a. Trong text box Filter: Tn b lc c t t ( y l filt2). Tn ny c th thay

i sau ny.

b. Nhp cc thng s thit k vo:

Response Type = Bandstop

Design Method = FIR Window

Specify Order: 62

Window: Kaiser, Beta: 4

Frequency Specifications: Fs = 8000, Fc1 = 2500, Fc2 = 2900.

c. Nhn Design Filter. Khi p ng tn s ca b lc thit k s c hin th.

3. Tr v ca s SPTool, trong ct Filters s xut hin thm mt dng filt2 [design].

y chnh l b lc va thit k. Thay i tn b lc trn thnh bs2700 bng cch

chn Edit Namefilt2 [design]. Trong ca s mi xut hin, nhp tn mi.

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Ghi li kt qu v kim tra xem y c phi b lc chn di nh mong mun khng?

Khi thit k mt b lc FIR nh trn, kt qu m ta cn nhn c sau khi thit k l cc gi

tr ca vector p ng xung h ca b lc thit k. ly cc gi tr ca vector p ng xung,

ta thc hin nh sau:

1. T ca s SPTool, chn File Export Trong Export list xut hin, chn

Filter: bs2700 [design] ri nhn nt Export to workspace

2. ng ca s SPTool li. Mt thng bo xut hin hi c mun lu li phin lm vic

hin ti hay khng. Nu mun lu li, chn Save.

3. M ca s Workspace ca MATLAB, ta s thy trong workspace s xut hin bin mi

l bs2700. y chnh l b lc m ta thit k trong SPTool v xut ra workspace ca

MATLAB. Bin ny c lu di dng mt cu trc m t b lc thit k. Nhn

p chut vo tn bin bs2700 trong workspace, ta s thy c cc field ca cu trc

ny.

4. Trong cc field ny, field tf th hin hm truyn ca b lc. Field ny cng l mt cu

trc gm 2 field: tf.num v tf.den th hin tng ng cc h s ca a thc t s v a

thc mu s. i vi b lc FIR, hm truyn ch c t s v cc h s ca t s chnh

l p ng xung ca b lc. Do , vi b lc trn, cc gi tr ca vector p ng xung

c lu trong bs2700.tf.num. Trong ca s Array Editor trn, ln lt nhn p vo

field tf ri nhn p vo num, ta s thy cc h s p ng xung ca b lc. gn cc

h s ny vo mt vector h, trong MATLAB c th dng lnh sau:

>> h = bs2700.tf.num

5. Cc gi tr thu c ca vector p ng xung s c s dng thc hin b lc s

ln trn kit DSP. Do chng trnh kho st b lc s ln trn kit DSP s dng ch 16

bit c du trong khi chng trnh thit k b lc bng MATLAB chun ha cc h s

p ng xung trong khong [-1 1] nn cc h s p ng xung ny cn nhn vi 215 v

lm trn v s nguyn trc khi a vo thc hin b lc s ln trn kit DSP nh sau:

>> cof = round(h*2^15)

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Ghi nhn gi tr cc h s ca p ng xung ny.

Thc hin b lc trn kit DSP

B lc ny c thc hin trn kit bng chng trnh sau (vit bng ngn ng C)

//Fir.c FIR filter. Include coefficient file with length N

#include "coefficients.h" //coefficient file

#include "dsk6713_aic23.h" //codec-dsk support file


int yn = 0; //initialize filter's output

short dly[N]; //delay samples

interrupt void c_int11() //ISR

{

short i;

dly[0]=input_sample(); //input newest sample

yn = 0; //initialize filter's output

for (i = 0; i< N; i++)

yn += (h[i] * dly[i]); //y(n) += h(i)* x(n-i)

for (i = N-1; i > 0; i--) //starting @ end of buffer

dly[i] = dly[i-1]; //update delays with data move

output_sample(yn >> 15); //scale output filter sample

return;

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}

void main()

{



}

Trong chng trnh ny, N l chiu di ca p ng xung ca b lc (bng M + 1 vi M l

bc ca b lc) v p ng xung ca b lc l mng h c kch thc N. Gi tr ca N v

vector h c khai bo trong tp tin coefficients.h. Tp tin ny c gp vo nh ch dn

#include. Nh vy, khi mun thay i b lc, ch cn thay i ni dung ca tp tin

coefficients.h.

Chng trnh trn c s dng ngt. Khi c c xung ly mu (tn s chn y l 8KHz),

trnh phc v ngt c_int11 c gi, c mu vo v thc hin gii thut x l mu tnh

ng ra.

(Hng dn: nn sao chp th mc FIR c thnh mt th mc vi tn khc v thc hin

trn th mc mi ny ng vi tng b lc).

Tm li, cc bc thc hin b lc FIR ln kit nh sau:

1. Ly cc h s p ng xung cof ca b lc thit k nh dng 16 bit c du.

2. M CCS (nh m ngun ca DSK trc khi m CCS). Kim tra kt ni.

3. M tp tin project ( c to sn) FIR.pjt trong C:\CCStudio_v3.1\myprojects\FIR.

4. Trong ca s Project View, tab File View, m rng phn Include, m tp tin

coeficients.h.

5. t cc h s p ng xung ca b lc va thit k vo trong tp tin ny. (C th copy

v paste t ca s Array Editor trn). iu chnh gi tr N cho ng vi chiu di p

ng xung. Lu rng cc gi tr ca p ng xung cch nhau bng mt du phy (,).

Lu tp tin sau khi sa i.

6. Xc lp cc ty chn ph hp (xem phn hng dn s dng trong ti liu ny) ri tin

hnh bin dch chng trnh. Sau khi dch thnh cng, hy np chng trnh ln trn kit

v chy chng trnh.

nh gi kt qu thc hin

1. Chn View Graph Time/Frequency. Thay i cc ty chn trong ca s Graph

Property Dialog v trong min thi gian. a ch bt u ca b m chnh l tn

mng h c nhp vo Start Address. Cc ty chn khc c th nh mc nh.

Ghi nhn dng sng p ng xung ca b lc:

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2. Chn View Graph Time/Frequency, sau chn Display type l FFT

Magnitude v a ch bt u (Start Address) l h. Chn bc ca FFT (FFT Order)

sao cho FFT Framesize = 2order

.

Ghi nhn p ng bin -tn s v pha-tn s ca b lc:

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Kim tra b lc:

1. M ngun ca my pht sng. To mt tn hiu vo hnh sine t my pht sng, ln lt

thay i tn s ca tn hiu vo t 100Hz n 4KHz (mi ln 100Hz), ghi nhn bin

dng sng v bin ph ca tn hiu ng ra t xc nh c tnh ca b lc.

Ch : u tin nn pht tn hiu sine tn s nm gia di thng ca b lc xc nh

bin tn hiu ng ra Am mc va phi trn mn hnh hin th. Sau , hiu chnh tn s

my pht theo yu cu. bo m ng ra khng b mo dng khi ng vo qu ln, nn ko

nt AMPLITUDE ra ngoi gim mc ti a ca bin ng vo.

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2. To mt sng vung t my pht sng, ln lt thay i tn s ca tn hiu vo ghi nhn

cc thnh phn tn s ca ng ra. Gii thch ti sao c dng ph ny?

fi (Hz) 100 200 550 900

fo (Hz)

Gii thch

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5.1.2. B lc FIR thng di

Tng t nh phn trn, hy thit k, thc hin v kim tra b lc FIR thng di bng

phng php Kaiser Window vi cc thng s nh sau:

Chiu di p ng xung: 63

Tn s ct: 1500 v 2000 Hz.

Gi tr ca = 5

Tn s ly mu: 8 kHz.

1. p ng tn s ca b lc thit k dng MATLAB:

2. Ga tr cc h s p ng xung ca b lc thc hin trn kit DSP:

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3. Dng sng p ng xung ca b lc thc hin trn kit DSP:

4. p ng bin -tn s v pha-tn s ca b lc thc hin trn kit DSP:

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5. Kim tra b lc vi ng vo tn hiu sin:





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6. Kim tra b lc vi ng vo tn hiu xung vung:

fi (Hz) 100 200 350 600

fo (Hz)

Gii thch

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5.1.3. B lc FIR thng cao

Tng t nh trn, hy thit k, thc hin v kim tra b lc FIR thng cao bng phng

php Kaiser Window vi cc thng s nh sau::

Chiu di p ng xung: 63

Tn s ct: 2200 Hz.

Gi tr ca = 4

Tn s ly mu: 8 kHz.

1. p ng tn s ca b lc thit k dng MATLAB:

2. Ga tr cc h s p ng xung ca b lc thc hin trn kit DSP:

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3. Dng sng p ng xung ca b lc thc hin trn kit DSP:

4. p ng bin -tn s v pha-tn s ca b lc thc hin trn kit DSP:

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5. Kim tra b lc vi ng vo tn hiu sin:





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6. Kim tra b lc vi ng vo tn hiu xung vung:

fi (Hz) 500 600 800 1000

fo (Hz)

Gii thch

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5.1.4. B lc FIR multiband

Thit k, thc hin v kim tra mt b lc FIR multiband gm 63 h s, tn s ly mu l 10

kHz, di thng [500 1000] Hz v [1500 2000] Hz, rng di chuyn tip 100 Hz. B lc

cn thit k c p ng tn s nh sau:

0 500 1000 1500 2000 2500 3000 3500 4000 4500 50000

0.2

0.4

0.6

0.8

1

1.2

Hnh 31. p ng tn s ca b lc multiband FIR cn thit k.

Thit k b lc dng MATLAB

B lc mong mun c 2 di thng, c biu din bi 5 di nh sau:

Di Tn s (Hz) Tn s chun ha f/FN Bin

1 0 500 0 0.1 0

2 600 900 0.12 0.18 1

3 1000 1500 0.2 0.3 0

4 1600 1900 0.32 0.38 1

5 2000 - 5000 0.4 - 1 0

trong FN l tn s Nyquist, bng tn s ly mu.

Chng ta vit mt file .m thit k b lc ny, lu li vi tn multibandfir63.m. Ni dung

ca file ny nh sau:

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Tn Dsp 2015-01-18 Sinhvien