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TRNG I HC BCH KHOA H NI

KHOA IN T- VIN THNG

NTT NGHIP I HC

ti:

XY DNG H THNG THU PHT TRN

NN DSP S DNG K THUT OFDM

Sinh vin thc hin: L NH NY

Lp T12 - K48

Ging vin hng dn: TS. NGUYN VN C

H Ni, 6-2008

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B GIO DC V O TO CNG HA X HI CH NGHA VIT NAM


--------------------------------------------------c lp - T do - Hnh phc

---------------------------------

NHIM V N TT NGHIP

H v tn sinh vin: L nh Ny.... S hiu sinh vin: 20032445

Kho: 48.Khoa: in t - Vin thng Ngnh: .........

1. u n:.. .....

2. Cc s liu v d liu ban u:......

......

3. Ni dung cc phn thuytminh v tnh ton:...

...

...

4. Cc bn v, th ( ghi r cc loi v kch thc bn v ):...

...

.

5. H tn ging vin hng dn: ..6. Ngy giao nhim v n: .7. Ngy hon thnh n: ..

Ngy thng nm

Ch nhim B mn Ging vin hng dn

Sinh vin hon thnh v np n tt nghip ngy thng nm

Cn b phn bin

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B GIO DC V O TO


---------------------------------------------------

BN NHN XT N TT NGHIP

H v tn sinh vin: L nh Ny............................................................ S hiu sinh vin: 20032445.............

Ngnh: .................................................................................................. Kho: 48 ....................................................

Ging vin hng dn: TS. Nguyn Vn c

Cn b phn bin: .......................................................................................................................................

1. Ni dung thit k tt nghip:..................................................................................................................................................................................................................................................

..................................................................................................................................................................................................................................................

..................................................................................................................................................................................................................................................

..................................................................................................................................................................................................................................................

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2. Nhn xt ca cn b phn bin:..................................................................................................................................................................................................................................................

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..................................................................................................................................................................................................................................................

........................................................................................

Ngy thng nm

Cn b phn bin

( K, ghi r h v tn )

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LI NI U

Ti xin chn thnh cm n thy gio Tin S Nguyn Vn c v cng

ng thi l gio vin hng dn ti, ngi lun tn tnh ch bo, dy d v mt

chuyn mn, ng vin khch l v mt tinh thn cho ti hon thnh n ny.

Ti cng mun ni li cm n ti b m, anh ch em v nhng ngi thn ca

ti. Nhng ngi lun theo st, ng h, ng vin ti trong qu trnh hc tp

cng nh lm n tt nghip ti trng i hc Bch Khoa H Ni.

Ti rt n lc hon thnh n ny. Tuy nhin, do thi gian gp rt

v kh nng c hn nn chc chn cn nhiu hn ch v thiu st. Ti rt mong

nhn c s ng gp kin ca qu thy c v bn b.

Xin chn thnh cm n.

H Ni, ngy 01 thng 06 nm 2008

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TM TT

Trong n ny em tm hiu l thuyt ca cng ngh OFDM, cc h

thng ng dng k thut ny, cc k thut iu ch s, thu pht v tuyn, ng

dng ca vi x l tn hiu s, cng vi vic s dng phn mm CCS ( Code

composer Studio) xy dng mt h thng vin thng s dng cng ngh

OFDM trong vic thu pht d liu s.

Vi quy m v thi gian thc hin ti, kt qu ca n t c

mc chy thnh cng trong vic truyn thng gia cc DSK6416 TI, tn hiu tmt DSK c pht ra ng line output v mt DSK khc nhn qua ng

line input. Cc chng trnh cng thnh cng trong vic truyn d liu gia

my tnh v DSK. y l mt hng nghin cu c th trin khai thc t v a

vo sn xut sn phm thu pht d liu khng dy.

ABSTRACT

In my thesis, I have learnd about theory of OFDM technique, the systems

using this technique, digital modutaion techniques, radio frequency, digital signal

processing, using CCS ( Code composer Studio ) to design an OFDM system in

wich we can transmit and receive digital data.The result of this thesis is complete the OFDM system with out

communication channels, transmit data from a computer or the line in of

DSK6416, receive data through the line out of DSK or store in computer. The

next step, we can intergrate the radio frequency, the estimation block, the

equalization block to the full system.

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MC LC

LI NI U .................................................................................................... 4

TM TT ........................................................................................................... 5MC LC .......................................................................................................... 6DANH MC HNH V ...................................................................................... 9DANH MC BNG BIU ............................................................................... 10CC T VIT TT ......................................................................................... 11M U .......................................................................................................... 13Chng 1 : H thng OFDM v qu trnh x l tn hiu ............. .............. ......... 14

1.1 Gii thiu v k thut ofdm. .................................................................... 141.1.1 Gii thiu ......................................................................................... 141.1.2 Lch s pht trin.............................................................................. 15

1.1.3 Cc u v nhc im ...................................................................... 151.2 Phng php iu ch v gii iu ch OFDM ............. .............. ........... .. 16

1.2.1 Khi nim v s trc giao ca hai tn hiu ............. .............. ........... .. 171.2.2 iu ch OFDM ............................................................................... 171.2.3 Gii iu ch ODFM ........................................................................ 20

1.3 H thng v tuyn s dng k thut OFDM ............. .............. ........... ...... 231.3.1 Khong bo v ................................................................................. 241.3.2 c lng knh truyn..................................................................... 261.3.3 ng b ........................................................................................... 301.3.4 Phng php iu ch v gii iu ch QAM ............ .............. ......... 321.3.5 V d mch iu ch QAM ............................................................... 381.3.6 nh hng s lng sng mang con v khong thi gian bo v ...... 39

1.4 Kt lun................................................................................................... 41Chng 2 Mt s h thng truyn dn s dng k thut OFDM ............ ............ 42

2.1 Gii thiu ................................................................................................ 422.2 H thng DRM ........................................................................................ 422.3 H thng HiperLAN (IEEE802.11a)........................................................ 442.4 H thng Wimax (IEEE802.16a,e) .......................................................... 452.5 Kt lun................................................................................................... 47

CHNG 3: X L TN HIU TRN DSP ............ .............. ............ ............. . 483.1 Gii thiu ................................................................................................ 483.2 TMS320C6416 DSK .............. .............. ........... .............. ........... .............. . 48

3.2.1 Tng quan v phn cng .................................................................. 483.2.2 Khi x l trung tm TMS320C6416 ............................................... 503.2.3 B nh.............................................................................................. 503.2.4 AIC23 .............................................................................................. 523.2.5 CPLD ............................................................................................... 533.2.6 Cc m rng (daughter card) ............................................................ 533.2.7 Cc yu cu to mt chng trnh cho DSK vi CCS ............. ..... 54

3.3 Kt lun................................................................................................... 55Chng 4: Bt u vi CCS .............................................................................. 56

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4.1 Gii thiu ................................................................................................ 564.2 Code composer Studio Tutorial ...................... ........... .............. .............. .. 564.3 Chu trnh xy dng v pht trin sn phm vi CCS.............. ............. ..... 564.4 Cu hnh h thng ( Creating a system configuration ) .............. .............. 564.5 Qun l cc thnh phn ............................................................................ 594.6 Kt lun................................................................................................... 59

Chng 5: Cng c qun l v bin dch CCS.................................................... 605.1 Gii thiu ................................................................................................ 605.2 Khi to project mi:............................................................................... 605.3 Xy dng v chy chng trnh: .............. .............. ........... .............. ......... 615.4 La chn cu hnh hot ng Project: ...................................................... 645.5 Thay i cu hnh hot ng ca project.................................................. 645.6 Add cu hnh hot ng mi cho project ................................................. 645.7 Thay i tn s cho DSK. ........................................................................ 655.8 im tm dng chng trnh khi chy (Breakpoint): ............. ............. ..... 655.9 im thm d ( Probe Point) ............ .............. ............ ............. ............. ... 665.10 Ca s quan st hot ng ca chng trnh ( Watch Window ) ............ 685.11 Kt lun................................................................................................. 69

Chng 6. Bt u CCS vi mt s ng dng n gin ............ .............. ........... 706.1 Gii thiu ................................................................................................ 706.2 Chng trnh Led .................................................................................... 70

6.2.1 M t v chng trnh led.c .............. .............. ........... .............. ......... 746.2.2 Thay i chng trnh led. ............................................................... 74

6.3 Chng trnh hello.pjt ............................................................................. 75

6.4 V d vi chng tr

nh Maxminmath ............. .............. ........... .............. ... 76

6.5 Chng trnh SineWave ........................ ............ .............. ............. ........... 786.6 Kt lun................................................................................................... 83

Chng 7 DSP/BIOS..................................................................................... 837.1 Gii thiu ................................................................................................ 837.2 Cc thnh phn ca DSP/BIOS .............. ............. ............ .............. ........... 84

7.2.1 DSP/BIOS API ............. ............. ............ ............. ............. ............. ... 847.2.2 DSP/BIOS Configuration ............. ............. ............ ............. ............. . 857.2.3 DSP/BIOS Analysis Tools .............. ............. ............ .............. ........... 86

7.3 Mt s v d ............................................................................................ 88

7.3.1 V d 1 Hellobios.pjt ....................................................................... 887.3.2 V d 2 Ledprd.pjt ............................................................................ 927.3.3 Chng trnh x l tn hiu volume thc hin bng DSP .............. ..... 94

7.4 Kt lun................................................................................................... 96Chng 8 K thut truyn thng........................................................................ 97

8.1 Gii thiu ................................................................................................ 978.2 iu phi truyn thng vi b m Ping pong ............ .............. ........... .... 978.3 S dng lin kt EDMA ( Linked EDMA transfers ) ............. ............. ..... 978.4 c im ca lung d liu truyn: ......................................................... 988.5 EDMA kt hp vi McBSP : ............ .............. ............ ............. ............. ... 99

8.6 Hot ng ca chng trnh: ................................................................. 1008.7 Cu hnh EDMA ( EDMA configuration manager):............. ............. ..... 100

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8.7.1 Thm i tng cu hnh EDMA: ..................... ............ .............. ... 1008.7.2 nh dng trng a ch ( Specifying Address Formats) .............. . 1018.7.3 McBSP handle (DRR) or (DXR): ....................... ........... .............. ... 1068.7.4 S khung truyn v ch s khung ( Transfer Count and Index Setting )................................................................................................................ 1088.7.5 Thit lp s khung truyn s dng file header (Transfer CountRegister Setting using the Users Header File) ........... ............. ............ .... 1098.7.6 Thit lp a ch lin kt ( Link address setting).............. ............. ... 1108.7.7 Thit lp bng Table Number: ........................................................ 1118.7.8 Cu hnh EDMA bng cc lnh trong file ngun. ............. .............. 113

8.8 McBSP ( Multichannel Buffered Serial Port ) ............. .............. ........... .. 1158.9 Cu hnh cho khi Codec AIC23 ........................................................... 1208.10 Mt s v d ........................................................................................ 121

8.10.1 Tone.pjt .............. .............. ........... .............. ............ ............. .......... 1218.10.2 Dsp_app ....................................................................................... 122

8.11 Kt lun............................................................................................... 125Chng 9 Truyn thng gia host v target ............. .............. ........... .............. . 126RTDX (Real-Time Data Exchange) ............ .............. ............ ............. ............. . 126

9.1 Gii thiu .............................................................................................. 1269.2 Chng trnh ng dng trn target (Target Application) ............ ............ 1269.3 Chng trnh ng dng trn host (Host Application basics) ............. ...... 1309.4 Pht trin ng dng vi VB ................................................................... 133

9.4.1 Phn 1 ............................................................................................ 1349.4.2 Phn 2 ............................................................................................ 135

9.4.3 Phn 3

............................................................................................ 139

9.4.4 Phn 4 ............................................................................................ 1409.4.5 Kt lun .............................................................................................. 140

TI LIU THAM KHO ............................................................................... 141Ph lc 1 ......................................................................................................... 142Ph lc 2 ......................................................................................................... 145Ph lc 3 ......................................................................................................... 148Ph lc 4 ......................................................................................................... 150Ph lc 5 ......................................................................................................... 152Ph lc 6 ......................................................................................................... 153

Ph lc 7 ......................................................................................................... 157Ph lc 8 ......................................................................................................... 164Ph lc 9 ......................................................................................................... 168

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DANH MC HNH V

Hnh 1.1 Biu din ph ca cc tn hiu OFDM18

Hnh 1.2 S b iu ch OFDM .......19

Hnh 1.3 M hnh mt knh truyn n gin .20

Hnh 1.4 S b gii iu ch OFDM.21

Hnh 1.5 M hnh tng quan h thng OFDM . ....23

Hnh 1.6 Khong bo v c cng vo k t OFDM . 25

Hnh 1.7 Tri tr nh hn khong bo v s khng gy ra ISI v ICI . 25

Hnh 1.8 S khi ca khi thu OFDM dng c lng knh....26Hnh 1.9 S khi c lng knh da trn pilot....27

Hnh 1.10 S khi b iu khin QAM..33

Hnh 1.11 Cc dng biu din 4 QAM.34

Hnh 1.12 Xung c s dng ch nht..35

Hnh 1.13 B iu ch I/Q...36

Hnh 1.14 S khi b gii iu ch QAM..36

Hnh 1.15 B gii iu ch I/Q....37

Hnh 1.16 iu ch v gii iu ch QAM-16....39

Hnh 1.17 QAM-16..39

Hnh 2.1 Mi trng truyn sng ca h thng DRM.43

Hnh 2.2 S khi ca h thng DRM..44

Hnh 2.3 M hnh truyn thng ca Wimax.....46

Hnh 3.1 Hnh nh bo mch TMS320C6416 DSK...48

Hnh 3.2 S khi ca bo mch.....49

Hnh 3.3 Phn vng b nhca C6416....51

Hnh 3.4 B chuyn i s - tng t AIC23...52

Hnh 4.1 Chu trnh xy dng v pht trin sn phm vi CCS....56

Hinh 9.1 Dng d liu gia RTDX host v target......125

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DANH MC BNG BIU

Bng 7.1 Cc module trong API c s dng trong chng trnh..84

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CC T VIT TT

ADSL Asymmetric Digital Subcriber Line

API Application Programming Interface

AWGN Additive White Gaussian Noise

BER Bit-Error-Rate

BOM Bill of Materials

BS Base Station

BSL Board Support Library

BTS Base Transceiver Station

CCS Code Composer Studio

CSL Chip Support Library

CMOS Complementary Metal Oxide Semiconductor

CODEC Coder-Decoder

CPLD Complex Programble Logic Device

CPU Central Processing Unit

DAB Digital Audio Broadcasting

DARAM Dual Access Random Access Memory

DIP Dual In-line Package

DMA Direct Memory Access

DRM Digital Radio Mondiable

DSK DSP Starter KitDSP Digital Signal Processor

EMIF External Memory Interface

FFT Fast Fourier Transform

HiperLan/2 High Performal Local Area NetWork Type 2

HPI Host Port Interface

IDE Integrated Development Enviroment

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IDFFT Inverse Fast Fourier Transform

IEEE Institute of Electrical and Electronic Engineers

ISI Intersymbol Interface

IQ Inphase-Quaderature

JTAG Joint Test Action Group

LED Light Emitting Diode

McBSP Mutil-Channel Buffered Sirial Port

MHz Megahertz

NMI Non-Maskable Interrupt

OFDM Orthoganal Frequency Division MultiplexingOS Operating System

PC Personal Computer

POST Power On Self Test

PLL Phase Locked Loop

PQFP Plastic Quad Flat Pack

QAM Quadrature Amplitude ModulationRF Radio Frequency

ROM Read-Only Memory

SDI Spectrum Digital Incorporated

SARAM Single Access Random Access Memory

SRAM Static Random Access Memory

SDRAM Synchronous Dynamic Random Access MemoryTI Texas Intruments

TTL Transistor-Transistor Logic

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M U

Thng tin v tuyn l lnh vc ang ni bt v pht trin nhanh chng trong

nhng nm gn y. Tc cao cho in thoi di dng, Lan khng dy, s pht

trin theo hm m ca Internet i hi phi c mt phng php mi t

c mng khng dy dung lng cao. OFDM K thut a sng mang phn

chia theo tn s trc giao vi nhng im ni bt nh s dng ph tn hn hiu

qu, truyn tc cao, c kh nng chng nhiuha hn s l mt cha kha

k thut cho cc ng dng v tuyn trong tng lai gn.

Quyn n ny ch yu tm hiu v thit k mt h thng s dng cng

ngh OFDM trn DSP ca TI, thc hin truyn dn trn h thng xy dng.

Ni dung c chia thnh cc phn sau:

Chng 1: gii thiu tng quan v cng ngh OFDM. Chng 2: tm hiu mt s ng dng ca cng ngh OFDM Chng 3: tm hiu kin trc ca dsk TMS320C6416 ca TI Chng 4: hng dn cch bt u lm vic vi CCS Chng 5: trnh by cc cng c xy dng, qun l, v bin dch

chng trnh ca CCS.

Chng 6: lm vic vi CCS thng qua mt s v d. Chng 7: tm hiu vDSP/BIOS v cch xy dng mt s chng

trnh n gin.

Chng 8: tm hiu v k thut truyn thng gia cc card DSP. Chng 9: tm hiu v xy dng chng trnh truyn thng gia host

v target.

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Chng 1 : H thng OFDM v qu trnh x l tn hiu

1.1 Gii thiu v k thut ofdm.

1.1.1 Gii thiu

a phng tin (multimedia) l cng ngh hiu qu c s dng trong

nhiu lnh vc khc nhau nh tnh ton, truyn thng, gii tr v xut bn. Cc

ng dng mi ang ni ln, khng ch trong mi trng truyn thng hu tuyn

m c trong mi trng v tuyn. Hin nay, ch c cc dch v s liu tc thp

cho ngi dng di ng. Tuy nhin, nhu cu v h thng a phng tin bng

rng khng dy ang c xem xt v dn c a vo trin khai c trong ccdch v cng cng cng nh trong dch v c nhn.

Truyn thng a phng tin c yu cu ln i vi bng rng v cht

lng dch v so vi nhng g hin c i vi ngi s dng di ng. Tc bit

cc ng dng s bin i t Kb/s cho thoi ti khong 20Mb/s cho HDTV v

thm ch cao hn.

gii quyt vn ny, cu hi t ra l lm cch no a dng d

liu c tc cao vo khng gian m vn m bo cht lng dch v. Mitrng v tuyn gy ra nhiu kh khn v s c nhiu sng phn x v cc hiu

ng khc. S dng b cn bng thch ng my thu c th gii quyt vn

nhng kh ng dng trong thc t vi thit b nh gn, chi ph thp. Mt cng

ngh c th loi b vic s dng cc b cn bng phc tp l cng ngh iu ch

phn chia theo tn s sng mang trc giao OFDM, mt cng ngh iu ch a

sng mang.

OFDM l mt cng ngh iu ch a sng mang, phng php ny chia

min ph s dng cho nhiu sng mang, mi sng mang c iu ch bi dng

s liu c tc thp.OFDM tng t nh FDMA ch nhiu ngi s dng

ph c hiu sut cao hn nhiu do khong cch cc knh rt gn nhau. iu ny

c c nh vic lm cho tt c cc sng mang trc giao nhau, trnh c nhiu

gia cc sng mang c khong cch gn nhau.

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1.1.2 Lch s pht trin.

K thut iu ch OFDM l mt trng hp c bit ca phng php iu

ch a sng mang trong cc sng mang ph trc giao vi nhau, nh vy ph

tn hiu cc sng mang ph cho php chng ln ln nhau m pha thu vn cth khi phc li tn hiu ban u. S chng ln ph tn hiu lm cho h thng

OFDM c hiu sut s dng ph tn hiu ln hn nhiu sovi cc k thut iu

chthng thng.

K thut OFDM do R.W CHANG pht minh nm 1966 M. Trong nhng

thp k va qua nhng cng trnh khoa hc v k thut ny c thc hin

khp ni trn th gii. c bit l cc cng trnh khoa hc ca Weisteil v Ebert,

ngi chng minh rng php iu ch OFDM c th thc hin c thng qua

php bin i IDFT v php gii iu ch OFDM c th thc hin c thng

qua php bin i DFT. Pht minh ny cng vi s pht trin ca k thut s lm

cho k thut iu ch OFDM c ng dng ngy cng tr nn rng ri. Thay v

s dng IDFT v DFT ngi ta c th s dng php bin i nhanh IFFT cho b

iu ch OFDM, FFT cho b gii iu ch OFDM. Ngy nay k thut OFDM

cn kt hp vi cc phng php m knh s dng trong thng tin v tuyn. Cch thng ny cn c gi vi khi nim l COFDM ( coded OFDM ). Trong cc

h thng ny tn hiu trc khi c iu ch OFDM s c m knh vi cc

loi m khc nhau vi mc ch chng li cc li ng truyn. Do cht lng

knh ( pha inh v t l tn hiu/ tp m ) ca mi sng mang ph l khc

nhau, ngi ta thc hin iu ch tn hiu trn mi sng mang vi cc mc iu

ch khc nhau. H thng ny m ra khi nim v h thng truyn dn s dng k

thut OFDM vi b iu ch tn hiu thchng. K thut ny hin c s

dng trong h thng thng tin my tnh bng rng HiperLAN/2 Chu u. Trn

th gii h thng ny c chun ha theo tiu chun IEEE.802.11a.

1.1.3 Cc u v nhc im

Bn cnh nhng u im k trn ca OFDM, cc h thng s dng k thut

ny cn c nhiu u im c bn lit k sau:

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H thng OFDM c th loi b hon ton nhiu phn tp a ng ( ISI)nu di chui bo v ln hn tr truyn dn ln nht ca knh.

Ph hp cho vic thit k h thng truyn dn bng rng ( h thng c tc truyn dn cao), do nh hng ca phn tp v tn s (frequencyselectivity ) i vi cht lng h thng c gim nhiu so vi h thng

truyn dn n sng mang.

H thng c cu trc b thu n ginK thut iu ch OFDM c mt vi nhc im c bn sau:

ng bao bin ca tn hiu pht khng bng phng. iu ny gy mophi tuyn cc b khuch i cng sut pha pht v thu. Cho n nay nhiu

k thut khc nhau c a ra khc phc nhc im ny.

S s dng chui bo v trnh c nhiu phn tp a ng nhng ligim i mt phn hiu sut ng truyn, do bn thn chui bo v khng

mang tin c ch.

Do yu cu v iu kin trc giao gia cc sng mang ph, h thngOFDM rt nhy cm vi hiu ng Doppler cng nh l s dch tn (

frequency offset ) v dch thi gian ( time offset ) do sai s ng b.Ngy nay k thut OFDM c tiu chun ha l phng php iu ch

cho cc h thng pht thanh s DAB v DRM, truyn hnh mt t DVB T,

mng my tnh khnng dy vi tc truyn dn cao HiperLAN/2,

1.2 Phng php iu ch v gii iu ch OFDM

H thng OFDM l h thng s dng nguyn l ghp knh phn chia theo

tn s trc giao, hot ng trn nguyn l pht d liu bng cch phn chia lungd liu thnh nhiu lung d liu song song c tc bt thp hn nhiu v s

dng cc lung con ny iu ch sng mang vi nhiu sng mang con c tn

s khc nhau. Cng ging nh h thng a sng mang thng thng, h thng

OFDM phn chia di tn cng tc thnh cc bng tn con khc nhau cho iu

ch, c bit tn s trung tm ca cc bng con ny trc giao vi nhau v mt

ton hc, cho php ph tn ca cc bng con chn ln nhau tng hiu qu s

dng ph tn m khng gy nhiu.

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1.2.1 Khi nim v s trc giao ca hai tn hiu

V mt ton hc xt tp cc tn hiu vi p l cc phn t th p ca tp,

cc tn hiu trong tp trc giao i mt vi nhau l:

* ,( ) ( )0,

a

p q

b

k p qa t a t dt

p q

Trong *( )q t l lin hp phc ca ( )

a

p

b

t . khong thi gian t a

n b l chu k ca tn hiu, cn k l mt hng s.

1.2.2 iu ch OFDM

Da vo tnh trc giao, ph tn hiu ca cc sng mang ph cho php chn

ln ln nhau. S chng ln ph tn hiu ny lm hiu sut s dng ph ca ton

b bng tn tng ln mt cch ng k. S trc giao ca sng mang ph c

thc hin nh sau: ph tn hiu ca sng mang ph th p c dch vo mt knh

con th p thng qua php nhn vi hm phc sjp t

e

, trong 2s sf l

khong cch tn s gia 2 sng mang. Thng qua php nhn vi s phc ny m

cc sng mang ph trc giao vi nhau. Tnh trc giao ca hai sng mang ph

c kim chng nh sau:

( 1) ( 1)

( )( )*s S

t t

s s

k T k T

jq j p qjp

kT kT

e e dt e dt

( 1)( )1( )

ss

s

t k Tj p q t

t kT

s

ej p q

0,

,s

p q

T p q

(1.2)

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phng trnh trn ta thy hai sng mang ph p v q trc giao vi nhau do

tch phn ca mt sng manglin hp phc vi sng mang cn li bng o nu

chng l hai sng mang khc bit. Trong trng hp tch phn vi chnh n s

cho kt quar l mt hng s. S trc giao ny l nguyn tc thc hin gii iu

ch OFDM

sjL te

fs

f-L Fo F+L

Hnh 1.1 Biu din ph ca cc tn hiu OFDM

f

Q

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Thc hin b gii iu ch thng qua php bin i IFFT

Trn hnh 1.2, gi dng bt trn mi lung song song l {ai,n }, sau khi qua

b iu ch QAM thnh tn hiu phc a mc {dk,n }. Trong n l ch s sng

mang ph, i l ch s ca khe thi gian tng ng vi Ncbit song sau khi quabbin i ni tip/ song song, k l ch s khe thi giantng ng vi Nc mu tn

hiu phc. Sau khi nhn vi xung c s, c dch tn v qua b tng th cui

cng c biu din nh sau:

',( ) '( )

Ljn t

k k n

n L

M t d s t kT e

(1.3)

Khi bin i lung tn hiu trn thnh s, lung tn hiu trn c ly muvi tn s:

1 1 sa

FFT s FFT

Tt

b N f N

(1.4)

Trong , B l ton b bng tn ca h thng. Ti thi im ly mu t =

kT+lta , S(t-kT)=s0, do vy phng trnh (1.3) c vit li:

B

phnnitip/songsong

iu ch bngcs (M QAM )

Xung

c s

Xungc s

Xungc s

Btng

Chnchuibov

Hnh 1.2 S b iu ch OFDM

sjL te

sjL te

sjL te

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( )0 ,' ( ) s s a

Ljn kT lt

k s a k n

n L

m kT lt s d e

0 ,s s s a

Ljn kT jn T

k n

n L

s d e e

2

0 ,FFT

nlL jnN

k n

n L

s d e

(1.5)Php bin tn hiu OFDM phng trnh 1.5 trng vi php bin i

IDFT. Do vy b iu ch OFDM c th thc hin d dng bng php bin i

IDFT. Trong trng hp NFFT l bi ca s 2, php bin i IDFT dc thay th

bng phng php IFFT.

u im ca phng php iu ch trc giao ODFM khng ch l s hiu

qu v s dng bng tn m cn c kh nng loi tr c nhim lin tn hiu

ISI thng qua s dng chui bo v. Do vy, tn hiu OFDM trc khi pht i

phi c chn thm chui bo v chng nhiu xuyn tn hiu.

1.2.3 Gii iu ch ODFM

phn tch qu trnh truyn tn hiu OFDm Mt cch n gin ta gi

thit mi trng truyn dn khng c can nhiu tp m trng. Mi lin h gia

tn hiu pht m(t), tn hiu thu T(u) v p ng xung ca knh h( , t) c m t

nh hnh sau:

min thi gian tn hiu thu l tch chp ca tn hiu pht v p ng

xung ca knh:

H(jw,t)h( ,t)

M(t) u(t)

Hnh 1.3 M hnh mt knh truyn n gin

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U(t) = m(t) * h(,t) (1.6)

S cu trc b gii iu ch OFDM c m t nh hnh di y. Tnhiu a vo b gii iu ch l u(t). Cc bc thc hin b gii iu ch c

chc nng ngc li so vi cc chc nng thc hin b iu ch:

- Tch khong bo v mi tn hiu thu.- Nhn vi hm s phc sjp te ( dch bng tn ca tn hiu mi

sng mang v bng tn gc nh trc khi iu ch)

- Gii iu ch cc sng mang ph. - Chuyn i mi tn hiu phc thnh dng bit.- Chuyn i dng bit song song thnh dng bit ni tip,ging dng

bit pht.

Thc hin b gii iu ch thng qua php bin i FFT

Tchchuibov

Chuynmuthnh bittn hiu

Gii

iu ch

Giiiu ch

Giiiu ch

Chuyni songsong /ni tip

sjL te

sjL te

sjL te

Hnh 1.4 S b gii iu ch OFDM

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B gii iu ch OFDM dng tng t l b tch phn dng mch s,

tn hiu c ly mu vi chu k ly mu l ta . Mt mu OFDM Tsc chia

thnh NFFT mu tn hiu:

a

FFT

TstN

(1.7)

Sau khi ly mu, tn hiu nhn c s l lung tn hiu s.

^

,k ld c

biu din nh sau:

1^

( )',1

( )

FFT

s s a

N

jl kT ntak l s a

ns

td u kT nt e

T

(1.8)

Nh trnh by trong phn gii iu ch ta bin i c nh sau:

1^2 /'

,0

1( )

FFT

FFT

Nj nl N

k l s a

nFFT

d u kT nt eN

(1.9)Biu thc trn chnh l bin i DFT vi chiu di l NFFT, Nu NFFT l

bi s ca 2 th ta c th thc hin bng php bin i FFT. Nh vy, ta c th

thc hin m hnh gii iu ch OFDM bng php bin i nhanh FFT.

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1.3 H thng v tuyn s dng k thut OFDM

Ngun bit l mt lung bit c iu ch bng tn c s thng qua

phng php iu ch nh QPSK, M-QAM. Tn hiu dn ng c chn vo

mu tn hiu, sau c iu ch thnh mu tn hiu OFDM thng qua b bin

i IFFT v chn chui bo v. Lung tn hiu s s c chuyn thnh lung tnhiu tng t qua b chuyn i s-tng t trckhi c chuyn thnh lung

tn hiu tng t qua b chuyn i s- tng t trc khi truyn trn knh v

tuyn qua anten pht. Tn hiu truyn qua knh v tuyn b nh hng bi nhiu

pha inh v nhiu trng.

Tn hiu dn ng v tn hiu bit c pha pht v pha thu, v c

pht cng vi tn hiu c ch vi nhiu mc ch khc nhau nh vic khi phc

knh truyn v ng b h thng.

iu ch bng tnc s

Chn mutn hiudn ng IFFT

Chnchuibo v

Bin is / tngt

Knh vtuyn

Nhiu

Bin itng t/ s

Tchchuibo v

FFTCn bngknh

Tch mutn hiu dnng

Khi phcknh truyn

Gii iuch bngtn c s

Ngunbit

Hnh 1.5 M hnh tng quan h thng OFDM

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My thu thc hin cc chc nng ngc li nh thc hin my pht.

Tuy nhin khi phc c tn hiu pht th hm truyn ca knh v tuyn

cng phi c khi phc. Vic thc hin khi phc hm truyn ca knh v

tuyn c thc hin thng qua mu tin dn ng nhn c pha thu. Tnhiu nhn c sau khi gii iu ch OFDM c chia lm hai lung tn hiu.

Lung tn hiu th nht l lung tn hiu c ch c a nb knh bng knh.

Lung tn hiu th hai l mu tin dn ng c a vo b khi phc knh

truyn. Knh truyn sau khi c khi phc cng s c a vo b knh bng

knh khi phc tn hiu ban u.

1.3.1 Khong bo vTc k t ca tn hiu OFDM thp hn nhiu so vi c truyn n

sng mang. Th d iu ch n sng mang BPSK, tc k t tng ng vi

tc bit truyn. Tuy nhin i vi k thut OFDM, lung d liu ng vo

c chia thnh N lung d liu song song pht i, kt qu l tc k t

OFDM gim N ln so vi tc truyn n sng mang, do n lm gim

c nhiu lin k t ISI b gy ra bi truyn a ng.

Hiu ng ISI trn tn hiu OFDM c th loi b hon ton bng cch cng

thm khong bo v trc mi k t. Khong bo v ny c chn sao cho ln

hn gi tr tri tr cc itrong mi trng cho cc thnh phn a ng ca

k t trc khng th giao thoa vi k t hin ti. Khong bo v c th l khong

trng ( khng c tn hiu g c ). Tuy nhin, nu ta s dng khong trng cho

khong bo v th s gy ra nhiu lin sng mang ICI, v khi cc sng mang

con nhn c my thu khng cn trc giao na. iu ny xy ra do ccthnh phn a ng ca k t khi nhn c my thu s khng c s nguyn

ln chu k trong thi khong FFT. loi b nhiu ICI th k t OFDM phi

c m rng chu k trong khong bo v m bo rng cc thnh phn a

ng ca k t lun c s nguyn ln chu k trong thi khoang FFT. Do c

m rng chu k nn khong bo v cn c gi l cyclic prefix ( tin t lp ).

Khong bo v c to ra bng cch copy mt s mu pha cui ca mi k t

OFDM v a ln u k t.

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Chiu di tng ca k t l TS=TG+TFFT, vi TS l tng chiu di ca k

t, TG l chiu di khong bo v, TFFT l kch thc ca IFFTc s dng

pht tn hiu OFDM.

Nh trn hnh 1.6, ta c thy rng nu di tr nh hn khong bo v s

khng c hin tng giao thoa gia k t trc v k t hin ti, do s khng

gy ra ISI v ICI. Tuy nhin do tn hiu nhn c ti my thu l tng ca nhiu

thnh phn a ng nn s gy ra s dch pha cho cc sng mang. Vic c

lng knh ca my thu s khc phc s dch pha ny.

IFFT GuardPeriod

IFFT output GuardPeriod

IFFT

Symbol N

TsSymbol N-1 Symbol N+1

TG TFFT

Time

Hnh 1.6 Khong bo vc cng vo k t OFDM

TG TFFT

Direct

Direct

Sampling period

Hnh 1.7 Tri tr nh hn khong bo v s khng gy ra ISI v ICI

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1.3.2 c lng knh truyn

Vic c lng nh bm theo knh truyn l cn thit trc khi gii iu

ch OFDM, bi v knh v tuyn l chn lc tn s v bin i theo thi gian

trong h thng di ng.

c lng knh c th thc hin c bng ccha tn hiu dn ng

(pilot) vo tt c sng mang con ca k t OFDM vi chu k ring hoc a mt

s tone pilot vo mi k t OFDM. Cch th nht, c lng knh pilot dng

khi (block), c pht trin di gi s knh fading chm. Thm ch vi b cn

bng feedback quyt nh, cng tha nhn rng hm truyn knh khng thay i

nhanh chng. Vic c lng knh sp xp pilot dng khi da vo LS(least

square: bnh phng ti thiu) hoc MMSE (bnh phng trung bnh cc tiu).

c lng MMSE (l s phc tp)vi li 10 15dB ca SNR, cho cng sai

s bnhphng ti thiu c lng knh LS [6]. Theo [7] xp x hng thp c

ng dng vi MMSE tuyn tnh, bng cch s dng hm tng quan tn s ca

knh loi b iu tr ngi chnh ca MMSE( l s phc tp). Cch th hai l

c lng knh pilot dng lc(comb), c a ra p ng cn thit cho cn

bng khi knh thay i nhanh, thm ch thay i ngay trong mt khi OFDM.

c lng knh pilot dng lc bao gm gii thut c lng knh ta tn s

pilot v ni suy knh.

Khi phc

knh truyn(c lngknh)

Tch

mu tnhiu dnng

Cnbngknh

Gii iuch bngtn c s

Tchchuibo v

Bin itngt/s

IFFT

Hnh 1.8 S khi ca khi thu OFDM dng c lng knh

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S c lng knh ti tn s pilot cho c lng dng lc c th da

vo LS, MMSE hoc LMS(least mean square). MMSE cho thy s thc hin tt

hn nhiu so vi LS. S phc tp ca MMSE gim xung xut pht t b c

lng ti u hng thp vi vic phn tch gi tr singular.Ni suy knh vi c lng dng lc c th dc vo: ni suy tuyn tnh,

ni suy bc 2 (second order), ni suy low- pass, ni suy bc 3, ni suy spline

cubic, ni suy min thi gian . . . Ni suy bc 2 thc hin tt hn ni suy tuyn

tnh. Ni suy min thi gian c chng minh l cho BER thp hn so vi ni

suy tuyn tnh.

M t h thng:

H thng OFDM c lng knh da vo pilot c bu din trong hnh

4.8. Thng tin nh phn th nht c nhm li v nh x ph hp vi iu ch

tn hiu mapper. Sau a pilot hoc tt c cc sng mang con vi chu kc

th hoc ng nht gia chui d liu thng tin, khi IDFT c s dng bin

i chui d liu c chiu di N{X(k)} ra tn hiu min thi gian {x(n) } theo

phng trnh:

Map S/PPilotInsertion

IDFT

GuardInserttion

P/S

GuardRemoval

DFTChannelestimateP/SDema

pS/P

Channel

Binarydata

Outputdata

Y(k) y(k) yf(k)

X(k)

h(n)

Xf(k)x(k)

AWGN

Hnh 1.9 S khi c lng knh da trn pilot

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1(2 / )

0

( ) {X(k)} ,n=0,1,2,...,N-1

1= ( )

Nj kn N

n

x n TDFT

X k e

n

(1.10)

Sau khi IDFT, khong bo v oc chn ln hn tri tr mong mun,

c a vo chng nhiu lin k t. Bng thng bo v ny bao gm thnh

phn lp li m rng ca k t OFDM loi b nhiu lin sng mang ( ICI).

Kt k t OFDM c cho bi:

1

0

( )L

j

l

l

H k h e

x(N+n) , n= -N , 1,.., 1( )

x(n) , n= 0,1,...N-1g g

f

Nx n

(1.11)

Vi Ng : chiu di ca khong bo v.

Tn hiu truyn xf(n) sau khi bin i t song song sang ni tip s c

a qua knh fadinh chn lc tn s v bin i theo thi gian, v c cngthm nhiu. ti b thu, tn hiu nhn c:

( ) ( ) w(n)f f

y x n h n (1.12)

Vi w(n): nhiu AWGN, h(n): p ng nhu xung knh truyn.

p ng xung knh truyn h(n) c th uc biu din:

1(2 / )

0

( ) ( )Dl nL

j N f T

l l

l

h n h e

(1.13)

Trong :

L: chiu di p ng xung knh truyn.

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H1: p ng xung phc ca ng truyn th l trong knh truyn ang ( L ng ).

fD1: dch tn s Doppler ca ng truyn th l. : ch s tri tr. T : chu k ly mu . l : thi gian tr ca ng truyn th l ( uc chun ha bi thi

gian ly mu ).

Ti b thu, sau khi qua b bin i A/D v b lc low pass, khong bo

v c loi b:

yf(n) , -Ng n N-1

y(n) = yf(n+Ng) , n= 0, 1, , N-1

Sau , y(n) c a n khi DFT:

1(2 / )

0

Y(k)= DFT{y(n)}

= ( )N

j kn N

n

y n e

(1.14)

Gi s khng c ISI, khi mi quan h gia Y(k) v H(k)= DFT{h(n)},

I(k) (nhiu ICI do dch Doppler), W(k)= DFT{w(n)} l:

Y(k)=X(k)H(k) + I(k) + W(k) , k = 0,1,2,,N-1 (1.15)

Vi:

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1(2 / )

0

sin( )( ) Dl l

Lj f T j kDl

l

l Dl

f TH k h e e

f T

2 ( )1 1(2 / )

(2 / )2 ( )0 0,

( ) 1( )

1

l

l

l

j f T k KL Nj d Kl

j N f T k Kl K

K k

h X K eH k e

N e

Sau khi qua khi DFT, tn hiu pilot c tch ra v c lng knhHe(k)cho nhng knh con t c trong khi c lng knh. Sau , d liu

truyn c c lng bng:

( )

( )e e

Y kX

H k , k = 0,1,,N-1 (1.16)

Sau cng, d liu thng tin truyn c c bng cachs nh x d liu tr

li trong khi Demap tn hiu.

1.3.3 ng b

ng b l nhim v c bn ca nhiu h thng tin s. Vic khng thc

hin gii thut ng b lm cho vic thu d liu truyn thng tin cy. T tung

ca k s thit k gii thut bng gc s, gii thut ng b l vn thit kchnh m phi c gii quyt xy dngv sn phm thnh cng.

H thng OFDM c nhiu li ch trong vic s dng hiu qu ph tn qua

tnh trc giao v iu ch thch nghi nh c trnh by chng trc. Ngoi

ra vi bn cht bng rng truyn tc cao t nhng d liu tc thp truyn

song song cho php h thng chng ISI, hin tng fadinh chn lc tn s gy ra

sai lch ch mt s sng mang con v vic khi phc trong OFDM c th s

dng FEC (forward error control)v c lnh knh b suy hao. Tuy nhin h

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thng OFDM vi chiu di k t ln lm cho n chy nhanh hn vi fadinh (

chn lc thi gian) gy bi hin tng dch doppler v s offset tn s sng

mang gia b thu v pht, dn n sng mang con trong h thng OFDM, mt

trc giao v gy nhiu ICI, dn n suy gim cht lng h thng. Vic ng btrong h thng OFDM cng cn thit i vi h thng OFDM, li nh thi k t

v li tn s ly mu gy ra hin tng xoay pha v mt trc giao. V vy vic

c lng knh truyn v ng b trong h thng OFDM l cn thit vic thu

d liu tin cy v hiu qa. Vic nghin cu hin ang tp trung vo cc gii

phu k thut cn bng gia tnh hiu qu v phc tp ca chng.

ng b trong h thng OFDM

Trong h thng OFDM, nhng sng mang ch hon ton trc giao nu

my pht v thu s dng nhng tn s hon ton ging nhau. Bt c s dch tn

s no cng lp tc gy ra ICI bi v sng mang ny khng cn trc giao na.

Mt vn c lin quan na l nhiu pha. Mt b giao ng trong thc t khng

th to ra mt sng mang chnh xc mt tn s, m thng to ra cc sng

mang c pha ngu nhin, dn n tn s 9 l o hm ca pha theo thi gian)

khng bao gi l

mt hng s v

th gy ra ICI trong OFDM. cc h thng n

sng mang, nhiu pha v dch tn s thng ch gim t s S/N my thu hn l

gy ra nhiu. y l l do ti sao m nhy vi nhiu pha v dch tn s l mt

im bt loi ca OFDM so vi h thng n sng mang. V vy vic ng b

my thu l mt vn rt quan trng trong h thng OFDM, n phi thc hin

c t nht 2 nhim v sau y:

- Th nht, n phi tm ra u l ng bin ca k hiu v khong thi gian

ti u lm gim ti a nh hng ca ICI v ISI- Th hai, n phi c long v chnh sa li dch tn s ca sng mang

nhn c trnh ICI. i vi nhng my thu kt hp, ngoi tn s, pha ca

sng mang cng cn uc ng b. Trong h thng OFDM, ngi ta thng

nhcn 3 loi ng b : ng b k t, ng b tn s sng mang v ng b

tn s ly mu.Mt s vn lin quan n x l tn hiu OFDM.

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1.3.4 Phng php iu ch v gii iu ch QAM

Trong h thng thng tin tng t, c 3 cch c bn iu ch sng

mang: AM, FM, PM. AM c trin khai trc v n d thc hin v d hiu.

n 1933 E.H. Armtrong pht trin FM, t nh hng bi nhiu hn AM.H thng thng tin s yu cu dung lng ln hn, cht lng tn hiu cao

hn, bo mt tt hn, tng thch vi d liu s. AM v FM cho thy s khng

tng thch vi nhng yu cu v ng truyn lu lng ln. Vi hng triu

thu bao s dng ht bng thng thoi, chng ta cn mt phng php iu ch

m c th truyn thng tin mt cch hiu qu v tin cy.

Cc phng php iu ch mi c pht trin nhanh trong vi nm tr

vtrc, kt hp c 3 phng php c bn trn. Kt hp vi cc k thut s, cc

phng php ny cho chng ta hiu qu vi cc u im ca k thut s so vi

k thut tng t.

V sao phi s dng iu ch s? Mt bng tn c bn c s ha c th

lm bt c th g. Chng ta c th gi n bt c khi no, gi xen gia cc

messages, hoc l tnh ton bng cc gii thut truyn vi s bt t hn, c

ngha l s dng t ti nguyn hn.Mt k thut iu ch thch hp vi x l s gi l IQ modulation. I

y l In-phase tham s pha ca sng mang. Vi nhiu kiu iu ch IQ a

dng, IQ l mt cch truyn thng tin hiu qu, v n cng rt ph hp vi dng

d liu s. Mt b iu ch IQ c th thc s to ra AM, FM v PM.

Khi iu ch mt sng mang vi dng sng c tn s thay i nh, ta c

th coi vic iu ch nh thc hin bin i pha ca sng mang. Khi pha ca

sng mang cha c phn thc v phn o, hay I v Q. Chng ta c th to ra b

thu v gii m thng tin trong sng mang bng cch c ra thnh phn I v Q

ca n.

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u tin dng d liu dng chui nh phn ly t ngun tin c chuyn

i thnh mu tn hiu phc nh sau

' '' | | kik k k k d d jd d e (1.17)

vi k {IN}

Trong dk v dk l cc gi tr thc, dkl mu tn hiu phc trong tp M

mu tn hiu khc nhau ca QAM.

dk {Am} vi k,m = 1,2,,M

Amc gi l mu tn hiu M-QAM.

T (1.11) ta thy tn hiu QAM c iu ch c v bin |dk| v pha

k .

Do c M mu tn hiu khc nhau nn cn L bit, vi L=log2M , cho vic

m ha mt mu tn hiu. L phi l s nguyn nn M phi ly gi tr l 2L cho

cc trng hp L = 1,2,3 ta c BPSK, 4-QAM, 8-QAM, 16- QAM v 32 QAM Hnh 1.2 th hin mt v d c th cho trng hp 4-QAM:

Chuyni bitthnhtn hiuphc

Xung c

s s(t)

Xung cs s(t)

BiuchI/Q

dk

Dngbit

dk mTI(t)

mTR(t)

m(t)

Hnh 1.10 S khi b iu ch QAM

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QAM kiu I, 0 = 0

QAM kiu II, 0 = / 4

cng thc 1.11, tn hiu nh phn sau khi c chuyn sang mu tn

hiu phc {dk} s c nhn vi xung cs s(t). Mc ch ca vic nhn vi

xung c s l ng b cch tn hiu pht v mt thi gian (ng b vi chu k

ly mu T) . C th l bin chui mu tn hiu phc t cc gi tr phc ri rc

jA

Am

A2

jAm

A3

-jA

A4

A0-A

Am

A1

Hnh 1.11 Cc dng biu din 4 - QAM

jA

Am

A2

jAm

A3

-jA

A4

A0-A

2-QAM 2-ASK

Am

A1

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thnh mt chui cc xung lin tip vi chu k xung l chu k ly mu v c

iu ch vi mt mu tn hiu phc nh sau.

0

( ) ( ) ( ) | | ( )kjT TR TI k k

m t m t m t d e s t kT

(1.18)Vic nhn vi xung c s ngoi nhim v ng b vi chu k ly mu cn

c tc dng gim nhiu lin tn hiu ISI pha my thu, ty thuc vo vic thit

k dng xung c s. Trng hp n gin nht ca xung c s l xung vung

hnh ch nht.

PT (1.12) th hin tn hiu QAM bng tn c s . Tn hiu ny c

iu ch c v bin v pha.

pht tn hiu i xa, tn hiu bng tn c s mT(t) phi c chuyn

ln tn hiu tn s cao thng qua b u ch I/Q nh sau:

s(t)

T t0

1

Hnh 1.12 Xung c s dng ch nht

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Tn hiu sau khi iu ch I/Q c biu din nh sau:

0

0 0

( ) Re {m (t) }

=m (t)cos ( )sin

j t

T

TR TI

m t al e

t m t t

(1.19)

Tn hiu m(t) c gi l tn hiu bng thng c a vo b khuch

i cao tn v tn x anten pht.

L thuyt v gii iu ch:

BgiiiuchI/Q

Ly mu

chu k T

Ly muchu k T

Chuyni muphcthnhdng bittn hiu

mTR(t)

m(t)

mTI(t) dk

dk

Dng bit

Hnh 1.14 S khi b gii iu ch QAM

mTR(t)cos0t

mTI(t) -sin0t

m(t)

Hnh 1.13 B iu ch I/Q

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T tn hiu m(t) thu c ta cn gii iu ch QAM thu c dng bit

ban u. B gii iu ch I/Q thc cht l b bin i tn hiu m(t) thu c

bng tn c s mT(t) .

Hnh (1.13) cho thy tn hiu m(t) thu c gm 2 thnh phn, bi vy sau

khi qua cc b nhn cos 0 t v sin 0 t ta s tch m(t) thnh cc thnh phn tn

cao v tn thp nh sau:

20 0 0 0( ). os ( ). os ( )sin . osTR TI m t c t m t c t m t t c t

0 01 1( ).(1 os 2 ) ( )sin 22 2TR TI m t c t m t t

0 0

1 1 1( ). os 2 ( )sin 2

2 2 2TR TR TI m m t c t m t t

(1.20)

20 0 0 0( ).( sin ) ( ). os ( sin ) ( ) sinTR TI m t t m t c t t m t t

cos0t

-sin0t

Hnh 1.15 B gii iu ch I/Q

B lcthng thp( LPF )

B lcthng thp( LPF )

m(t)

mTR(t)

mTI(t)

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0 01 1

( ).sin 2 ( )(1 os2 )2 2TR TI

m t t m t c t

0 01 1 1( ) ( )sin 2 ( ) os2 )2 2 2TR TR TRm t m t t m t c t

(1.21)

Tn hiu s(t) sau khi qua cc b nhn cos 0 t v sin 0 t c a vo b

lc thng thp loi b cc thnh phn tn cao ly ra thnh phn c tn s

bng tn c s l mTR(t) v mTI(t).

Cc tn hiu lin tc mTR(t) v mTI(t) c chuyn i thnh cc mu tn

hiu ri rc dk v dk thng qua b ly mu vi chu k ly mu bng vi chu k

xung c s pha pht nhm m bo ng b tn hiu thu vi tn hiu pht.

Cui cng cc mu tn hiu ri rc qua b chuyn i symbol to bits

thu c dng bit ban u truyn i.

1.3.5 V d mch iu ch QAM

t c tc iu ch cao ngi ta kt hp iu ch ASK vi PSK. V

d trng hp c bit l iu ch PSK-18P t c dng hn l QAM-16.

iu ch QAM-16 ta c th kt hp ASK 4 mc vi PSK 4P. Xem hnh di

iu ch QAM-16. Dng s liu c chia thnh hai dng s liu song song ri

qua mch bin i thnh tn hiu 1 chiu 4 mc (1 mc s tng ng vi 2 bit ).

Cc tn hiu ny s ln lt c iu ch bi cc sng mang cos v sin sau

cng li vi nhau.

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Hnh 1.16 iu ch v gii iu ch QAM-16

Hnh 1.17 QAM-16

1.3.6 nh hng s lng sng mang con v khong thi gian bo v

Xt h thng OFDM 64 sng mang con s dng iu ch 16 QAM vi

mt knh a ng 2 tia. Cng sut ca tia th hai nh hn 6dB so vi tia th

nht. Nhiu my thu c b qua xem xt nh hng ca ISI v ICI hiu

nng h thng tng ng vi hai tham s ny.

900

900

iu ch Gii iu ch

cos0t cos0t

sin0tsin0t

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Hin tng t nhiu lm cho mt s im tn hiu vt qua cc bin quyt

nh v lm gim cp tng i hiu nng BER. Do cc b cn bng knh

mt pha phi c trin khai ti u ra FFT sa mo bin v mo pha gy

bi tr a ng.

i vi h thng OFDM 64 sng mang con vi b cn bng mt hng

ti my thu, khi thi gian tr truyn a ng cng tng th nhiu ISI cng tng

khi tr ln hn khong thi gian bo v, dn ti lm tng BER ca h thng.

nh hng ca ISI c th lm gim c bng cch tng thi gian k hiu

OFDM, xc nh nh hng ta nh ngha mt s o:

= ( tr truyn lan ) / ( thi gian k hiu )

Vi rng bng tn hiu OFDM cho trc, thi gian k hiu t l vi s

lng sng mang con, nu ln, mt lng ln cc mu k hiu OFDM khc

nhau b nh hng bi ISI v do h thng c BER cao v ngc li. Ta thy

rng ISI cng gim hn khi h thng OFDM c s lng sng mang con cng

tng. Tuy nhin, khi s lng sng mang con tng nhiu lm thu hp khongcch tn s gia chng khin chng d b hiu ng doppler.

Cc k hiu OFDM thi gian di mm do hn vi fading la chn tn s

nhng nhy cm hn vi fading la chn thi gian. Fading la chn thi gian

lm mt tnh trc giao gia cc sng mang con. Vi mt rng bng cho trc,

khong cch tn s gia cc sng mang con gim khi s sng mang con tng.

Khong cch tn s gia 2 sng mang con nh lm chng d b ICI do dch tngy bi hiu ng Doppler ca knh.

nh hng ca s sng mang con v khong thi gian bo v n hiu

nng h thng c tng kt nh sau:

Vi s lng sng mang con cho trc, tng khong bo v s lm

gim ISI do gim t l tr thi gian k hiu, nhng ng thi cng l m

gim hiu qu cng sut v hiu qu bng tn.

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Vi rng bng tn tn hiu cho trc, tng s lng sng mang con

tng hiu qu cng sut nhng cng tng thi gian k hiu lm cho h

thng nhy cm hn vi tri ph doppler.

1.4 Kt lun

Ni dung ca chng u tin ny l nhng vn c bn lin quan n k

thut phn knh theo tn s trc giao. Hiu c nhng vn c bn ca

OFDM, chng ta s hiu c kh nng ng dng ca n, v lm c s khi thit

k k thng thu pht s dng k thut OFDM ny.

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Chng 2 Mt s h thng truyn dn s dng k thut

OFDM

2.1 Gii thiuCng ngh OFDM ngy cng c ng dng rng ri. S kt hp gia k

thut s v k thut vi mch DSP c kh nng tnh ton nhanh gip to tn hiu

OFDM n gin v hiu qu. Nh vy OFDM c ng dng rng ri trong

nhiu h thng thng tin khc nhau nh: h thng pht thanh s, h thng truyn

hnh mt tV chng ny chng ta s n vi mt s h thng truyn dn

s dng cng ngh OFDM.

2.2 H thng DRM

DRM l h thng pht thanh s thay th cho h thng pht thanh iu tn

truyn thng FM. Tn s sng mang cho h thng DRM tng i thp, c th l

nh hn 30MHz, ph hp cho vic tuyn sng khong cch ln. Mi trng

truyn sng ca h thng l knh phn tp a ng c s tham gia phn x ca

mt t v tng in li nh m t hnh 3.1. Phm vi ph sng ca DRM do vy

rt ln, c th l a quc gia, hoc lin lc a. Do s dng k thut s v cng

ngh OFDM, cht lng tn hiu ca h thng DRM tng i tt.

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Hnh 2.2 m t s khi mt h thng DRM, trong h thng c th

truyn ti c d liu v m thanh v cc dch v khc. S s dng m ha knh

cho php sa li pha thu.

Cc tham s c bn ca h thng c a ra nh sau

B rng bng tn B = 9,328 kHz di FFT NFFT = 256 di chui bo v TG = 5.3 ms S sng mang s dng truyn tin Nc = 198

400km400km

Truyn dn khong cch nh( Gc pht gn thng ng) Truyn dn khong cch ln( Gc pht thp)

Hnh 2.1 Mi trng truyn sng ca h thng DRM

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M hnh knh truyn dn

Tham s Tuyn phn x th nht Tuyn phn x th 2

Tr truyn dn axm 0 1,664 ms

Tn s Doppler ln

nht fD

1 Hz 1Hz

T m hnh knh truyn dn ta thy knh truyn dn c tr truyn dn ln,c ngha l knh tng i nh so vi khong chc gia hai sng mang. H

thng DRM c thit k ch cho cc my thu tnh hoc xch tay. iu ny khc

hn so vi h thng DAB, thng ny c thit k cho c cc my thu c tc

chuyn doongj tuowong di ln nh otoo, tu ha,v.v.v

2.3 H thng HiperLAN (IEEE802.11a)

H thng HiperLAN/2 tng ng vi tiu chun IEEE802.11a cthit k cho mng my tnh khng dy WLAN. Tc truyn dn ln nht h

M hangun

Tin mha

Tin mha

Tin mha

Ghpknh

Phntnnnglng

Mhakh

Cixen

nhx

Phtpilot

M haknh

M haknh

Phn tn nnglng

Phn tn nnglng

iu chtn hiuOFDM

iuch

Dng dliu mthanh

D liu

Thngtin truycpknhnhanh

Thngtin mt dchv

Bo vbnhthng

Bo v cao

Bo vbnhthng

Bo v cao

Bo vbnhthng/ cao MSC

FAC

SDC

Hnh 2.2 S khi ca h thng DRM

TnhiuDRM

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thng c th cung cp c vo khong 54 Mbit/s ty thuc vo mi trng

truyn dn. B rng bng tn s dng l 20 MHz v c khai thc vng tn s

khong 5 GHz. Mi trng truyn dn l trong nh v gia cc ta nh.

Khong cch truyn dn tng i nh khong vi mt n vi trm mt.Cc tham s c bn ca h thng c lit k nh sau

B rng bng tn: B = 20 MHz di FFT: NFFT = 64 Chu k ly mu ta = 1

B= 50 ns

di chui bo v TG = 0.4 s i vi mi trng truyn dntrong nh v khong 0.8 s i vi mi trng truyn dn ngoi

tri.

2.4 H thng Wimax (IEEE802.16a,e)

Wimax (IEEE-1) ra i nhm cung cp mt phng tin truy cp Interneet

khng dy tng hp c th thay th cho ADSL v WLAN. H thng WiMax c

kh nng cung cp ng truyn vi tc ln n 70 Mb/s v vi bn knh phsng ca mt trm anten pht ln n 50 km. M hnh ph sng ca mng

Wimax tng t nh mng in thoi t bo. Mt h thng Wimax nh m t

hnh 3.3 gm 2 phn:

Trm pht: ging nh cc trm BTS trong mng thng tin di ngvi cng sut ln c th ph sng mt vng rng ti 8000

2km .

Trm thu: C th l cc anten nh nh cc Card mng cm vohoc c thit lp sn trn Mainboard bn trong my tnh, theo

cch m WLAN vn dng.

Cc trm pht BTS c kt ni ti mng Internet thng qua cc ng

truyn tc cao ring hoc c th c ni ti mt BTS khc nh mt trm

trung chuyn bng ng truyn thng (line of sight), v chnh v vy Wimax c

th ph sng n nhng vng rt xa.

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Cc anten thu/pht c th trao i thng tin vi nhau qua cc tia sng

truyn thng hoc cc tia phn x. Trong trng hp truyn thng LOS (Line of

sight), cc anten c t c nh trn cc im cao, tn hiu trong trng hp

ny n nh v tc truyn c th t ti a. Bng tn s dng c th dng tn s cao n 66 GHz v tn s ny tn hiu t b giao thoa vi cc knh tn

hiu khc v bng thng s dng cng ln hn. i vi trng hp c vt chn

NLOS ( non line of sight ), Wimax s dng bng tn thp hn, 2-11GHz, tng

t nh WLAN, tn hiu c th vt qua cc vt cn thng qua phn x, nhiu

x, un cong, vng qua cc vt th n ch.

Hnh 2.3 M hnh truyn thng ca Wimax

H thng Wimax c cc c chnh sau (IEEE-1):

Khong cch gia trm thu v pht c th ti 50 km. Tc truyn c th thay i, ti a 70 MHz. Hot ng trong c hai mi trng truyn dn: ng truyn tm

nhn thng LOS v ng truyn che khut NLOS.

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Di tn lm vic 2-11 GHz v t 10-66 GHz hin v ang ctiu chun ha.

Trong Wimax hng truyn tin c chia thnh hai ng ln vxung. ng ln c tn s thp hn ng xung v u s dngcng ngh OFDM truyn. OFDM trong Wimax s dng ti a

2048 sng mang, trong c 1536 sng mang dnh cho thng tin

c chia thnh 32 knh con mi knh con tng ng vi 48

song mang. Wimax s dng iu ch nhiu mc thch ng t

BPSK, QPSK n 256- QAM kt hp cc phng php sa li d

liu nh ngu nhin ha, vi m ha sa li Reed Solomon, m

xon t l t n 7/8. rng bng tn ca Wimax t 5 MHz n trn 20 MHz c chia

thnh nhiu bng con 1,75 MHz. Mi bng con ny c chia nh

hn na nh cng ngh OFDM, cho php nhiu thu bao c th

truy cp ng thi mt hay nhiu knh mt cch linh hot m

bo tit u hiu qu s dng bng tn. Cng ngh nay c gi l

cng ngh a truy nhp OFDMA (OFDM access)

Cho php s dng c hai cng ngh TDD ( time division duplexing) v FFD (frequency division duplexing ) cho vic phn chia truyn

dn ca hng ln (uplink) v hng xung (downlink )

V cu trc phn lp, h thng Wimax c phn chia thnh 4 lp:lp con tng ng (Convergence) lm nhim v giao din gia lp

a truy nhp v cc lp trn, lp a truy nhp (MAC layer ), lp

truyn dn (Transmission) v lp vt l (Physical). Cc lp ny

tng ng vi hai lp di ca m OSI v c tiu chun ha c th giao tip vi nhiu ng dng lp trn.

2.5 Kt lun

Chng ny cho chng ta thy ng dng ca cng ngh OFDM trong mt

s h thng thng tin v truyn dn. Trong tng lai chc chn cng ngh OFDM

s cn c mt vai tr quan trng hn cng vi nhiu ng dng rng ri trong

nhiu h thng truyn thng, truyn dn.

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CHNG 3: X L TN HIU TRN DSP

3.1 Gii thiu

Trong i sng cng nh trong k thut ngy nay, k thut s c ngdng v s dng rt rng ri. Nn vic nghin cu, s dng cc phng php x

l tn hiu s l rt quan trng. Mt trong nhng phng php c s dng

nhiu l phng php dng cc loi vi iu khin. Trong chng ny ta s nghin

cu vi iu khin TMS 320C6416 DSP do Texas instrument sn xut. M c th

l tm hiu TMS320C6416 DSK, y l mt mch tch hp cc linh kin phc v

hot ng ca con vi x l ch C6416. Mch ny c sn xut tin dng cho

vic nghin cu, hc tp, m phng t i n nhng ng dng thc t. Cc

linh kin tch hp trn bo mch vic th, lp trnh, ng dng ca vi x l l

thun li nht. Sau y l trnh by c im c bn nht ca bo mch v phng

php hot ng ca n.

3.2 TMS320C6416 DSK

3.2.1 Tng quan v phn cng

Hnh nh ca c bo mch:

Hnh 3.1 Hnh nh bo mch TMS320C6416 DSK

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TMS320C6416 DSK l mt mch thuc h TI C64xx DSP. Mch c

thit k cho vi x l TMS320C6416. Sau y l s n gin ca mch

Hnh 3.2 S khi ca bo mch

Mch gm cc thnh phn c bn sau:

Mt vi x l TMS320C6416 hot ng tn s 600 hoc720MHz Mt b bin i s-tng t AIC23 16Mbytes SDRAM 512 Kbytes b nh Flash 4 LED v 4 chuyn mch cho ngi dng Thanh ghi logic CPLD Cc khe cm giao tip vi b nh ngoi v thit b ngoi vi Giao tip vi my tnh qua cng USB bi kt ni JTAG Cng ngun (+5v)

Trn y l cc linh kin c s dng trong mch, tip theo ta nghin

cu c th cc khi ca mch

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3.2.2 Khi x l trung tm TMS320C6416

TMS320C6416 DSP hot ng tn s 720MHz. DSP c sn xut vi

cng ngh cao, n l tch hp ca nhiu vi mch vi chc nng c ci tin rt

nhiu. Khi vi x l bao gm mt s khi c bn sau: VLIWcore: y l mt cu trc x l cho php x l nhiu yu cu ti

mt thi im ( 6416 DSP l 8 ) trong mt xung ng h trong khi vn

hot ng tc cao. Cu ca VLIW c th t tc x l cc k cao

nhng vn tin dng cho ngi lp trnh thng qua code composer

1Mbyte b nh trong vi tc truy nhp rt cao On chip PLL( vng kha pha trn chip): To ra xung ng h cho chip

t xung ng h vi tn s nh hn bn ngoi.

EDMA Controler: iu khin lm tng tc truyn d liu m khngcn s can thip ca khi trung tm.

3McBSPs: y l phn m giao tip gia khi x l trung tm vi thitb ngoi vi. Mi McBSP c th s dng truyn d liu tc cao vi

thit b ngoi vi hay chc nng vo ra. McBSP2 s dng truyn v

nhn tn hiu m audio t AIC23. McBSP1 s dng iu khin vic mha trong khi bin i A-D. McBSP0 kt ni vi thit b ngoi vi.

EMIFA l bus giao tip gia khi x l vi b nh ngoi hoc cc thit bkhc c th kt ni, bus s dng l 64 bit.

EMFIB l bus cng dng kt ni vi b nh ngoi hoc cc thit bkhc nhng ch dng 16 bit. N c s dng trong nhng trng hp

tm thi hay l khi khng cn bng thng ln.

Trn y ta tm hiu cu trc c bn ca khi x l trung tm, l b phn quan

trng nht ca bo mch, n iu khin mi hot ng ca h thng. Sau y ta

tm hiu v b phn lu tr ca h thng, l b nh.

3.2.3 B nh

H vi x l C64xx c kh nng to ra b nh ln, vi khng gian a ch

ln, dng 32 bit a ch. Vi C6416 c s phn b a ch vng nh sau:

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Hnh 3.3 Phn vng b nhca C6416

Vi mc nh a ch bt u c nh t b nh trong ca khi x l,

ni cha m lnh. Sau tip tc n vng nh ngoi nh c ch ra trn

hnh.

DSK s dng 64 megabit SDRAM, giao tip bi bus CE0 ca EMIFA, 64bit. DSK s dng xung ng h cho EMIFA l 120MHz. Khi s dngDRAM cn lu l mi hng ca ma trn nh s c lm ti sau mi

khong thi gian l 15,6 mirco giy.

DSK s dng b nh ngoi l 512 Kbyte Flash. N kt ni vi CE1 caEMIFB vi giao din 8 bit. Flash l dng b nh khng b mt khi mt

ngun. Khi c n cng khng c nh c ROM. Flash c th xa v ghi

li nhiu ln qua phn mm. Flash yu cu 70 ns cho c c v ghi.

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3.2.4 AIC23

DSK s dng b Texas Instrument AIC23 ( #TLV320AIC320 ) bin

i s - tng t cho tn hiu audio vo v ra. Tn hiu tng t c th vo qua

ng MIC IN hoc l ng LINE IN chuyn i sang dng s m DSP cth x l. Sau khi kt thc qu trnh x l, tn hiu s c th chuyn i ngc li

thnh tn hiu tng t v xut ra ngoi thng qua ng Headphone hoc ng

LINE OUT. B chuyn i s - tng t s dng hai knh iu khin. Mt knh

iu khin thanh ghi trong nh dng cho b m ha. Mt knh c chc nng gi

v nhn cc mu tn hiu s v tng t. McBSP1 c s dng v hng

iu khin knh. N s c chng trnh gi mt t iu khin nh dng

thanh ghi. Cn 9 bit thp l gi tr thanh ghi. Knh diu khin ch s dng khi

nh dng khi to cho b m ha, n thng c s dng khi tn hiu m

thanh ang c truyn.

Hnh 3.4 B chuyn i s -tng tAIC23

McBSP2 c s dng nh l mt knh tn hiu c hng. Tt c tn hiu

m thanh s dc truyn qua knh ny. Nhiu d liu nh dng s c c bn

cung cp trn ba bin l rng mu, ngun tn hiu ng h v ngun nh

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dng d liu. Cc v d ca DSK thng s dng mu c rng l 16 bit m

ha, n to ra khung ng b v xung ng h chun ha tn s ly mu.

B m ha c h thng ng h 12 MHz ny ph hp vi tn s ca USB

v nhiu h thng USB s dng ng h 12MHZ v cng c th dng chungng h cho b m ha v iu b iu khin USB. C th to ra nhiu tn s

nh hn t tn s c s ny, nh cc tn s 48KHz, 44.1 KHz v 8KHz. Tn s

ly mu c th c khi to bng thanh ghi SAMPLERATE.

3.2.5 CPLD

C6416 DSK s dng mt thit b logic tch hp c kh nng lp trnh

c l EMP312TC100-10. N bao gm cc phn chnh l: 4 vng nh iu khin trng thi thanh ghi n cho php iu khin

phn mm v s thay i trn bo mch.

a ch gii m v b nh truy nhp logic. iu khin giao din v tn hiu ca daughter card. Lin kt logic cc b phn trn bo vi nhau.

CPLD c s dng vi chc nng c bit trn DSK. Phn cng ca ta

c thit k vi cng ngh cao, n c chc nng v u im ln khi DSP hot

ng mc cao m ta khng cn dng cc thit b logic ngoi.

CPLD cng l mt thit b c hm logic ngu nhin m khng cn thit b

no thm. Hn na, CPLD t hp cc bin tn hiu khi dng n t nt reset v

qun l ngun v to ra lnh khi to ton cc.

EMP312TC100-10 s dng ngun 3,3V (c th chp nhn l 5V), vi 100

chn QPF, 80 chn vo ra, tr t chn ny ti chn kia l 10ns. Thit b cEEPROM-base v mt h thng trong kh trnh iu khin dnh cho giao din

JTAG. File ngun ca CPLD c vit bi ngn ng VHDLv c lu trong

DSK.

3.2.6 Cc m rng (daughter card)

DSK cung cp ba kt ni m rng c th s dng ni cc ci. Cc n y

cho php kt ni trn nn DSK, cung cp cc ng dng cho ngi dng hoc l

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cng vo ra. Kt ni m rng ny l b nh ngoi, thit b ngoi vi, v Host Port

Interface (HPI).

B nh kt ni c cung cp truy nhp vi tn hiu ng b EMIF ca

DSP c giao din vi cc b nh khc v s b nh ca DSP, c cung cpmt khng gian ring bit. a ch nh l 32 bit nh ta tm hiu trn. S kt

ni ny thng qua McBSPs, ngt, v ng h. Cc kt ni ny cng cung cp

ngun v t cho cc m rng.

HPI l mt giao din c tc cao, n c cho php thc hin nhiu giao

tip vi DSP. Kt ni HPI a tn hiu ra, iu khin tn hiu tt nh l

McBSP2.

3.2.7 Cc yu cu to mt chng trnh cho DSK vi CCS

DSK TM32C6416 do Texas Instrument sn xut v phn phi, ngoi

mch chnh, cn cc ph kin i km nh dy ngun, dy kt ni vi my tnh

qua cng USB, a ci Code Composer Studio( CCS ).

DSK kt ni vi my tnh thng qua cng USB.Qua y chng trnh s

c np vo DSK thng qua phn mm Code Composer Studio, l phn

mm s dng ngn ng C lp trnh cho DSK.C giao din cho ngi dng.

Cc bc to mt chng trnh cho DSK:

Ci t phn mm Code Composer Studio trn my tnh. Cm ngun v kt ni vi cng USB my tnh Kim tra li cc kt ni bng phn mm Thc hin chng trnh

Sau khi ci t CCS trn my tnh, ta thy cc biu tng sau:

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Chng 4: Bt u vi CCS

4.1 Gii thiu

CCS l phn mm i km theo DSK, n l trnh son tho, g li cngnh bin dch cc chng trnh ca chng ta.

4.2 Code composer Studio Tutorial

Bt u hng dn CCS bng cch chnHelp Tutorial

Phn ny bao gm cc bi ging gip chng ta lm quen nhanh vi CCS

IDE. CCStudio Tutorial cho php bn rt ngn thi gian hc CCS ng thi cung

cp cho bn cc thng tin c bn v cc th tc.

4.3 Chu trnh xy dng v pht trin sn phm vi CCS

4.4 Cu hnh h thng ( Creating a system configuration )

CCS cho php chng ta cu hnh h thng lm vic vi h phn cngkhc nhau. Chng ta c bt u lm vic nhanh bng cch cu hnh cc h thng

mc nh theo cc cu hnh chun m CCS cung cp. Chng hn h thng

5000TMC th c file h thng chun l 55 TMC x v h thng 6000TMC chng ta c

file h thng chun l 64 TMC x . 6000TMC 55 TMC x

CCS cho php chng ta la chn cch cu hnh h thng s dng cc file

h thng chun hoc khi to cc file cu hnh theo yu cu ca ngi s dng

cc file cu hnh ring.

Thit kKhi nimLp k hoch

Vit m vxy dngProject, vitfile ngun vfile cu hnh

G liKim tracu trcKho st

Phn tchthi gianthc, g li,thng k,ha li.

Hnh 4.1 Chu trnh xy dng v pht trin sn phm vi CCS

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Cc bc khi to cu hnh h thng s dng cc file cu hnh h thng

chun:

Bc 1: Bt u bng cch click p vo biu tng SetupCCStudio

Bc 2: Click vo Remove All trong hp thoi SystemConfiguration loi b cc cu hnh nh ngha trc .

Bc 3: ClickYes chng thc lnh Remove All. Bc 4: Chn cu hnh chun ph hp t cc cu hnh c sn

nh hnh sau:

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Bc 5: Clickphm Add chn cu hnh va la chn. Cuhnh la chn s hin th pha di biu tng My System

icon trong bng System Configuration ca ca s Setup.

Nu bn mun cu hnh cho nhiu h thng khc nhau th hy

lp li cc bc 4 v 5. Phn bn phi ca ca s CodeComposer Studio Setup l cc thng tin m t cu hnh la

chn. Chng ta xem xt xem cu hnh c ph hp vi h

thng ca chng ta khng. Nu khng ph hp chng ta c

th thay i li bng cch clickphm Modify Properties. Sau

khi khai bo cc thng s thch hp ta clickOK.

Bc 6: Click phm Save&Quit lu li cu hnh va lachn v bt u lm vic vi CCS.

Bc 7: ClickYes bt u lm vic vi CCStudio khi thot khi to CCStudio. Ca s Setup CCStudio ng v

CCStudio IDE t ng m ra cho ta s dng vi cu hnh h

thng va to.

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Bn c th bt u lm vic vi CCStudio IDE.

4.5 Qun l cc thnh phnQun l cc thnh phn l thanh cng c cao cp s dng chnh ty

chnh hoc sa li cc khi to ca bn. Ch s dng cc thanh cng c ny

gii cc tng tc gia cc b phn trong ty chnh hoc khi to nhiu mi

trng lm vic.

Ta c th m Compoment manager:

Bc 1: T menu help chn About hp thoi About CCSxut hin

Bc 2: Click button Compoment ManagerTa c th m Compoment Manager bng cch vo:

C:\ti\cc\bin\comp_mgr.exe

4.6 Kt lun

Chng ny ch cho chng ta cch cu hnh cho phn mm ph hp vi

cu hnh ca DSK m chng ta s lm vic.

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Chng 5: Cng c qun l v bin dch CCS

5.1 Gii thiu

Cng c qun l v bin dch CCS cho php chng ta bt u lm vic viCCS mc c bn t vic khi to mt chng trnh n vic bin dch v g

li. Bn cnh cn c thm cc cng c h tr cho qu trnh lm vic ca

chng ta tr nn d dng hn. C th nh cc phn di.

5.2 Khi to project mi:

Cc bc khi to d n mi:

Bc 1: T menu chn NewHp thoi xut hin.

Bc 2: Chn cc thng s tng ng vi h thng ca bn vclickFinish

Sau khi to project mi th ca s sau xut hin:

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5.3 Xy dng v chy chng trnh:

xy dng v chy chng trnh ta thc hin theo cc bc sau:

Bc 1: Vit cc file ngun cho chng trnh. y l cc filec dngfile.c. to ra cc file ngun ny chng ta vo File

New Source file. Cc cu lnh trong chng trnh ca chng

ta s c to ra ti y. Sau chng ta s lu file ngun li

bng cch click File Save as. Chn ng dn cho file

ngun vo ng th mc cha project ca chng ta, khai bo

tn v clickSave.

Bc 2: Add cc file vo project bng cch click chut phi lntn ca project ang lm vic bn phi ca ca s chng

trnh CCS, chn Add Files to Projectnh hnh sau.

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Bc 3: Chn file ngun ( file.c ) va to ra v clickOpen. Bc 4: Add cc file th vin vo chng trnh. y chng

ta lm vic vi chip C6416 nn chng ta s Add file rts6400.lib

trong th mc C:\Program

Files\CCStudio_v3.1\C6000\cgtools\lib vo chng trnh nh

Add file ngun bc 3.

Bc 5: ClickScan All File Dependencies tham chiu ccfile.hvo chng trnh. Ccfile.h ny s t ng c to ra.

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Bc 6: Chn Project Rebuild All hoc click vo biutng trn thanh cng c.

Bc 7: Theo mc nh th file .out s c to ra ti th mccha Project. thay i ni cha file.out to ra ta chn bng

cch vo Project/build option/link.. Bc 8: Chn Fileload Program. Chn file.outva to ra

v clickOpen.

Bc 9: Chn ViewMixed Source/ASM. La chn ny scho php chng trnh to ra ng thi code C v cc on

code Assembly tng ng trong qu trnh chy.

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5.7 Thay i tn s cho DSK.

5.8 im tm dng chng trnh khi chy (Breakpoint):

c dng nh du cc im dng khi thc thi chng trnh. N gip

chng ta chy v kho st ring tng on chng trnh. to im tm dng

chng trnh khi chy chng ta di chut ti im m chng ta mun chng trnh

s dng khi chy, click chut phi v chn Toggle Software Breakpoint nh

hnh di hoc n vo biu tng trn thanh cng c.

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Khi gc mn hnh ti im nh du s xut hin du chm

nh hnh sau

Mun hy b im BreakPiont no th ta clickp chut tri ln dng

lnh cha im y. Cn nu ta mun hu b tt c cc im BreakPoint th ta

click ln biu tng trn thanh cng c ca CCS.

5.9 im thm d ( Probe Point)Trong CCS cch n gin nht truyn thng d liu gia host ( c th l

my tnh ni vi DSP ) v target ( DSP ) l dng Probe point. Chng ta s to ra

cc im ny bng cch di chut n v tr ta mun kho st qu trnh vo ra d

liu. Click chut phi v chn Toggle Software Probe pointnh hnh v sau

hoc click ln biu tng trn thanh cng c ca CCS.

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Khi y gc mn hnh s xut hin du hiu nh hnh di y.

Mun hy mt im Probe Point ta click chut phi ln v tr cha im

y v la chn nh hnh di. Cn nu mun hy tt c cc im Probe Point

th ta click ln biu tng trn thanh cng c ca CCS.

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Mt hn ch khi s dng Probe point kho st qu trnh truyn thng

gia target v host l n ch cho php chng ta vo ra cc file hex nh dng l

file.dat

5.10 Ca s quan st hot ng ca chng trnh ( Watch Window )

Ca s ny kt hp vi Break point s cho chng ta quan st c cc

kt qu ca chng trnh khi n tm dng. Gi s xem kt qu ca mt bingane ti im chng trnh dng ta se khai bo gain vo trong ca s Watch1

nh hnh sau

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Qua ca s ny chng ta cng c th bit kt qu cc gi tr ca mt

mng. Chng ta cng c th thay i gi tr tm thi ca bin khai bo mt cch

tm thi, y l Gain bng cch cho gi tr mi ti min Value. Khi chng

trnh s tip tc chy vi gi tr mi ca Gain l gi tr va khai bo.

5.11 Kt lun

Chng ny trnh by mt cch c bn qu trnh lm vi phn mm CCS t

vic to mt project mi ti vic s dng mt s cc cng c n gin thc

hin vic truyn thng gia host v target hoc kho st chng trnh ti cc

im ngt. chng sau chng ta s hiu r hn v cc cng c ny cng nh

lm quen v s dng cc cng c khc ca CCS qua vic thc hin mt s cc v

d n gin.

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Chng 6. Bt u CCS vi mt s ng dng n gin

6.1 Gii thiu

chng trc chng ta bit cc bc c bn to mt chng trnhcng vi cc cng c c bn m chng ta c th dng xy dng chng trnh

ca chng ta. chng ny chng ta s hiu r hn v chng thng qua cc v

d c th sau.

6.2 Chng trnh Led

Cch d nht bt u vi CCS l chy cc ng dng n gin vi DSK.

V d v n LED l v d d nht ta lm quen vi mi trng pht trin vcu hnh cho DSK. Trc tin chng ta s copy th mc led theo ng dn

c:\ti\examples\dsk6416\bsl\sang mt th mc khc lm vic m khng s lm

thay i chng trnh gc hin c. y ti chng trnh led th mcE:\Ny

luu\Dien tu vien thong\Do an tot nghiep\Tot nghiep\Cac chuong trinh\led.

Khi chy n s nhp nhy n led#0 l 2.5 ln / 1s Thay i DIP Switch 3 s thay i trng thi ca Led#3.

thc hin chng trnh ta thc hin cc bc sau:

MProject Open v chn file led.pjttrong ng dnE:\Nyluu\Dien tu vien thong\Do an tot nghiep\Tot nghiep\Cac chuong

trinh\led.

ClickReBuild All l biu tng trn thanh cng c bindch li chng trnh led ca chng ta. Chng ta se thy CCS

bo li. l do chng ta coppy chng trnh sang Folder khc

lm thay i ng dn tham chiu ti mt s file.h v file th

vin dsk6416bsl.lib ca chng trnh. sa li ny chng ta

vo folder C:\ti\c6000\dsk6416\include coppy cc file

dsk6416.h, dsk6416_led.h, dsk6416_dip.h v vo ng dn

C:\ti\c6000\dsk6416\lib coppy fle dsk6416bsl.lib vo folder

cha chng trnh led ca chng ta. y l cc file m CCScung cp sn cho chng ta. Trong c cc nh ngha cng nh

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Ca s Build Opption xut hin. Trong Tab Compiler chnPreProcessor Include Search Path ta nhp ng dn ti

folder cha Project ca chng ta l E:\Ny luu\Dien tu vien

thong\Do an tot nghiep\Tot nghiep\Cac chuong trinh\led nhhnh sau

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Chn Tab Linker chn Basic v trong Library Search Path ta

khai bo li ng dn nh hnh sau.

ClickOk kt thc vic khai bo li ng dn.

ClickReBuid All bin dch li chng trnh. Ln ny chngtrnh c bin dch thnh cng.

Chn File Load Program. Mt hp thoi m ra, chn fileled.outtrong ng dn/debug/led.out.

Chn Debug Run chy chng trnh. Led#0 bt u nhpnhy.

Chuyn DIP Switch #3 ln v xung ta s thy Led#3 thay itrng thi theo.

dng chng trnh ta chn Debug Halt.

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xem code ca on chng trnh trn ta kickp vo file led.c. Ca s

cha on m ngun s xut hin cho chng ta lm vic nh hnh di.

Code ca chng trnh ny c vit trong ph lc 1.

6.2.1 M t v chng trnh led.c

Bt u bng hm main(). u tin ta gi hm DSK6416_init() v n

c to trong th vin BSL ( Board Support Library ). Th vin ny gip chngra d dng s dng cc thnh phn ca bo mch DSK.DSK6416_init() c gi

ra trc cc hm BSL khc. Cc hm trong th vin ny bt u bng DSK6416.

Cc hm ny trong th vin c tn l dsk6416bsl.lib.

6.2.2 Thay i chng trnh led.

Ta thay i tc nhp nhy ca n led bng cch thay i hm nh sau.

/* To nhp nhy vi thi gian sng v tt 200ms */

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DSK6416_waitusec(200000);

Thnh: /* To nhp nhy vi thi gian sng v tt 100ms */

DSK6416_waitusec(100000);

Sau khi sa li chng trnh ta thc hin cc bc sau:

Chn File Save lu chng trnh va thay i. Thc hin bin dch li chng trnh bng cch chn

Project Build.

Ti li file led.out bng cch chn File Load Programv chn/debug/led.out.

Chn Debug Run chy chng trnh. Mun dng chng trnh li th chn Debug Halt.

6.3 Chng trnh hello.pjt

Chng trnh ny ch n gin hin th dng ch Hello World. u

tin chng ta s coppy folder hello1 theo ng dn C:\Program

Files\CCStudio_v3.1\tutorial\sim64xx sang mt v tr khc nhm trnh nhng

thay i khi lm vic. y ti coppy vo folderE:\Ny luu\Dien tu vien

thong\Do an tot nghiep\Tot nghiep\Cac chuong trinh. Sau chng ta m project

hello.pjt. S c mt thng bo hin ra nh hnh sau

Thng bo ny yu cu chng ta chn li ng dn cho file th vin

rts6400.lib. cho nhng ln khai bo sau c d dng vi vic tm kim v tr

file ny chng ta s coppy n t folder C:\Program

Files\CCStudio_v3.1\C6000\cgtools\lib vo folder ca chng ta v chn ng

dn vo folder ny.

Bin dch li chng trnh. Load file hello.outv cho chy chng ta s c

kt qu nh hnh sau.

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Code ca chng trnh ny c vit ph lc 2.

6.4 V d vi chng trnh Maxminmath

Vi v d ny chng ta s bit cch t to cho mnh mt file th vin

( file.lib ) thc hin mt s chc nng no . Cch tham chiu vo file th vin

ny s dng cc hm chc nng vo chng trnh chnh ca chng ta. Cc

bc thc hin v d ny l.

Bc 1: To ra folder MaxminMath cha chng trnh ca chngta.

Bc 2: To cc file testapp.c v maxminvalue.c vi code ccho ph lc 3. Trong maxminvalue cha hai hm l

minimumValue() v maximumvalue.c().

Bc 3: To Project mi vi tn l maxminlibrary v chn dngfile c to ra l .lib nh hnh sau

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ClickFinish. Bc 4: Add file rts6400.lib, maximumvalue.cvo chng trnh. Bc 5:ClickReBuild All. File maximumvalue.libc to ra

trong forlder\MaxminMath\maxminlibrary\Debug.

n y ta to ra c mt file th vin. File th vin ny c cha

on chng trnh tm gi tr ln nht ca mng. By gi chng ta s tin

hnh xy dng mt chng trnh v n s tham chiu n file th vin va c

to ra s dng hm chc nng maximumvalue() ca n. Cc bc khi to

Bc 1: To project mi vi tn l mainapplication.pjtvi ProjectType l .out.

Bc 2: Add file testapp.c v rts6400.libvo chng trnh. Bc 3:ReBuild Allchng trnh. S c thng bo li. Nguyn

nhn l do trong file testapp.c ta c gi cc hm maximumValue()

v minimumValue() trong th vin maximumvalue.lib nhng tacha Add n vo Project. By gi ta cn phi Add n vo chng

trnh ca chng ta.

Bc 4: Load file mainapplication.outv chy th. Chng ta se ckt qu hin ra nh hnh sau.

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6.5 Chng trnh SineWave

V d ny thc hin vic truyn thng mc n gin gia host

v target bng cch dng Break Point v Probe Point. Chng trnh ny thc

hin np file sine.dat t my tnh vo trong DSP. D liu nhn c s c

DSP x l ( y ch n gin l nhn cc gi tr nhn c vi hng s gain = 5

) sau ta truyn kt qu ngc li cho my tnh. Kt qu ca qu trnh x l ny

s c lu li trn my tnh di dng file l bigSine.dat. Thc hin v d ny

thng qua cc bc sau:

Bc 1: Click Open Project vo ng dn C:\ProgramFiles\CCStudio_v3.1\tutorial\sim64xx. M file sinewave.pjt.

Bc 2:ReBuild Allchng trnh v load file sinewave.out vac to ra.

Bc 3: M file ngun sine.c v nh du im Probe Point tidng dataIO() trong hm main() nh hnh sau

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Bc 4: ClickFile File I/O. Ca s File I/O xut hin nh hnhdi.

Bc 5: Click Add File. Ca s File Input xut hin. Chng tachn ng dn ti folder sinewave v m file sine.dat.

Bc 6:ClickAdd Probe Point ca s Break/Probe Pontscm ra nh hnh sau

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Click chut ln dng sine.c line 30. trong trng Probe Point.

Trong trng Connect To chn FILE IN: E:\..\sine.datnh hnh trn.

ClickReplacev sau ClickOK. Bc 7: Trong hp thoi FILE I/O ti trng Address g vo

currentBuffer.input v ti trng Length g vo s 100nh hnh

di. ClickOK.

Bc 8: ClickFile File I/O. Click Tab File Output. Add filebigsine.dat. ClickAdd Probe Point. Trong Probe Pointclickln

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sine.c line 30.trong trng Probe Point. Trong trng Connect

To chn FILE IN: E:\..\bigsine.dat. Clickln phm Add ta s c kt

qu nh hnh di.

Bc 9:Trong h

p thoi File I/Oti trng Address

gcurrentBuffer.output v ti trng Length g 100. Kt qu nh

hnh di.

ClickOK.

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Bc 10:ClickRun chy chng trnh. Bc 11: Click Haft dng chng trnh. Kim tra li file

bigsine.datta s thy dung lng ca n tng ln.

Bc 12: Clickview Watch Window. Trong Tab Watch1 gcurrentBuffer.input. Cho chy chng trnh chng ta s c bng

sau.

Chng ta c th thy ngay cc gi tr ca mng currentBuffer.input

(currentBuffer.output) cc gi tr u vo v u ra. Chng ta c th

thay i tm thi cc gi tr ny chy chng trnh ca chng

ta.Vic ny s khng nh hng g ti file sine.dat gc.

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6.6 Kt lun

Chng ny gip chng ta lm quen vi vic xy dng mt chng trnh,

g li v load n v chy. Chng ta cng bit cch to mt file th vin, cch

dng chng trong chng trnh ca chng ta. Chng ta cn c th thc hintruyn thng mc n gin gia my tnh v target thng qua im d probe

point.

Chng 7 DSP/BIOS

7.1 Gii thiu

DSP/BIOS l mt thit k cho cc ng dng yu cu ng b thi gian

thc, truyn thng gia host-to-target cng vi cc cng c phn tch thi gian

thc. DSP/BIOS cung cp nhiu on tuyn c mc u tin khc nhau, trutng ha phn cng v phn tch thi gian thc.

DSP/BIOS c ng gi di dng cc module v c th lin kt vo

trong ng dng ca chng ta. Cc ng dng kt hp vi cc hm chc nng ny

ca DSP/BIOS ( trc tip hoc gin tip ) v chng s c tham chiu ti trong

ng dng. Thm vo , cng c DSP/BIOS cho php ti u ha kch thc v

tc bng cch v hiu ha cc tnh nng m chng ta khng s dng.

Chng ta c th s dng DSP/BIOS o c phn tch qu trnh lm vic

bng cch kho st ( probeb), phc ha (traced), v hin th trong min thi gian

thc. Cc chng trnh s dng DSP/BIOS Configuration Tool s tn dng c

kh nng a phn tuyn ( multi threading ) ca DSP/BIOS.

DSP/BIOS c tch hp vi Code Composer Studio, v c h tr hon

ton bi Texas Instruments.

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MBX Mailbox manager

PIP Buffered pipe manager

PRD Periodic function manager

RTDX Real-time data exchange settingsSIO Stream I/O manager

SWI Software interrupt manager

TSK Multitasking manager

Bng 7.1 Cc module trong API c sdng trong chng trnh

7.2.2 DSP/BIOS Configuration

DSP/BIOS configuration cho php chng ta khi to v cu hnh cc c tnh

ca Dsp/Bios s dng cho chng trnh ca chng ta.

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7.2.3 DSP/BIOS Analysis Tools

Cc cng c phn tch h tr cho mi trng CCS bng cch cho phpphn tch tnh thi gian thc ca cc ng dng DSP/BIOS. Ta c th gim st

trc quan mt ng dng DSP khi n ang chy vi s nh hng ln tnh thi

gian thc ca cc ng dng l nh nht. DSP/BIOS analysis tools c a vo

trong DSP/BIOS menu, th hin nh trong hnh di y:

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Khc vi cc cng c debug truyn thng, cc cng c trn c m rng

thc thi chng trnh, iu ny yu cu chng trnh pha target phi cha cc

lnh thi gian thc. Bng vic s dng cc API v cc i tng, ngi pht

trin s t ng o c pha target bt gi v ti li cc thng tin thi gian

thc ln cho host thng qua DSP/BIOS analysis tools ca Code Composer

Studio.

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