HỆ-THỐNG-NHẬN-DẠNG-BIỂN-SỐ-XE-ỨNG-DỤNG-CÔNG-NGHỆ-XỬ-LÝ-ẢNH

8/12/2019 H-THNG-NHN-DNG-BIN-S-XE-NG-DNG-CNG-NGH-X-L-NH

1/68

BGIO D"C & $O T%OTR'(NG $%I H+C S'PH%M K,THU/T TP. H0CH MINH

KHOA $I1N $I1N T3BMN $I1N T3-CNG NGHI1P

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

$0N T5T NGHI1PNGNH K,THU/T $I1N - $I1N T3

$6TI:

H1TH5NG NH/N D%NG BI7N S5XE

8NG D"NG CNG NGH1X3L :NH

GVHD : ThS. NGUY;N V


2/68

!n t$t nghi%p i

GVHD: ThS. Nguy'n V)n Nga Ph,n A: Gi-i thi%u

PH>N A

GI?I THI1U


3/68

!n t$t nghi%p ii


$0N $'@C HON THNH T%ITR'(NG $%I H+C S'PH%M K,THU/T TP. H0CH MINH

Cn b0h1-ng d2n: ThS. Nguy'n V)n Nga

Sinh vin th3c hi%n: Nguy'n Thanh i4nL5i Qu$c Quang

Cn b0ch6m ph7n bi%n: ..

! n t$t nghi%p 815c b7o v% t9i H:I


4/68

!n t$t nghi%p iii


TRDENG H. SDPHHM KJTHUMT CNG HA X HI CHANGHBA VI1T NAMTP. H


5/68

!n t$t nghi%p iv


L(I C:M )N&

Sau h.n b$n thng th3c hi%n, chng em 8 honthnh 8! n 8ng th_i gian quy 8`nh cba nh tr1_ng. C 815c kctqu78 ngoi s3ndl3c cba nhm th3c hi%n 84ti cn c s3h1-ngd2n tQn tnh cba th,y h1-ng d2n, qu th,y c trong khoa i%n-i%ntRv cc b9n sinh vin trong l-p 07101BD.

Chng em chn thnh c7m .n qu th,y c trong khoa i%n-i%n tR8 tQn tnh gi7ng d9y v truy4n 89t nhZng kicn thec qu bucho chng em trong su$t nhZng n)m hNc qua.

Chng em xin gfi l_i chn thnh c7m .n th,y NguyEn VInNga8 tQn tnh h1-ng d2n, chgb7o v chia sinhZng kicn qu bu8Vchng em c thVhon thnh t$t 8!n ny.

!ng th_i, chng con xin c7m .n cha mjv gia 8nh 8 80ngvin v fbn chng con trong su$t th_i gian hNc tQp ftr1_ng v ticnhnh 8!n n.

Cu$i cng xin gRi l_i c7m .n 8cn cc b9n l-p 07101BD 8chia si trao 8ki kicn thec clng nh1 nhZng kinh nghi%m qu bu

trong th_i gian th3c hi%n 84ti.Xin chn thnh c7m .n!

Trn trKng

Nhm th3c hi%n 8!n

Nguy'n Thanh i4nL5i Qu$c Quang


6/68

!n t$t nghi%p v


L(I NI $>UNgy nay, khoa hNc kOthuQt ngy cng pht triVn m 8mc bi%t l cng ngh%kO

thuQt 8i%n tRv cng ngh%xRl 7nh. V thc, cc thch%vi m9ch 8 khng ngnng c7iticn v pht triVn 8V8p eng nhZng nhu c,u phXc vX cho 8_i s$ng con ng1_i ngycng thuQn ti%n h.n. S3kct h5p giZa cc thch%vi 8i4u khiVn cng v-i cng ngh%nhQnd9ng t380ng d3a qua vi%c l1u trZdZli%u tnxa sRdXng thict b`thiv 8,u 8Nc thisolm cho vi%c qu7n l dZli%u clng nh1xRl 7nh trfnn thuQn ti%n h.n.

VvQn dXng nhZng kicn thec 8 hNc nhpm thict kcm0t h%th$ng eng dXng vo8_i s$ng, ng1_i hNc ph7i tch lly nhZng kOn)ng lQp trnh, kicn thec c.b7n v chuynsu. !ng th_i, ng1_i hNc ph7i nghin ceu l thuyct, thict kc, thi cng m9ch m-i cthVhiVu r nguyn l ho9t 80ng cba s7n phqm thi cng. chnh nhZng kOn)ng cbasinh vin ngnh kOthuQt i%n-i%n tR.


7/68

!n t$t nghi%p vi


NH/N XT CAA GIO VIN PH:N BI1N

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Tp. HCM , ngy thng n#m 2012

Gio vin phMn biNn


8/68

!n t$t nghi%p vii


NH/N XT CAA GIO VIN H'?NG DON

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Tp. HCM , ngy thng n#m 2012

Gio vin hPQng dSn


9/68

!n t$t nghi%p Trang 1

GVHD : ThS. Nguy'n V)n Nga Ch1.ng 1: D2n nhQp

1.1 L do chKn TUtiNgy nay, khoa hNc kO thuQt ni chung v kO thuQt 8i%n tR ni ring 8ang pht triVn

nhanh chng v-i hng lo9t cc gi7i php cng ngh%8i%n tRra 8_i m eng dXng cba n vo8_i s$ng l r6t quan trNng. Chnh v thc, cc sinh vin hNc ngnh cng ngh%8i%n tRkhngnhZng ticp thu cc kicn thec f8 hNc m cn ph7i tm hiVu v nghin ceu thm cc cngngh%8i%n tR tin ticn trn thcgi-i, 8Vc thV8p eng 815c yu c,u cao cba th`tr1_ng lao80ng. S3ra 8_i cba RFID l m0t t1fng 80c 8o v l m0t cng ngh%m-i, 8ang d,n honthi%n v 815c 8nh gi c nhi4m ti4m n)ng 8Vthay thccng ngh%m v9ch trong t1.ng laikhng xa. Vi%c nhanh chng nghin ceu, lm chbv 81a cng ngh%ny vo eng dXng th3cti'n fVi%t Nam somang l9i nhZng l5i ch to l-n.

S3kct h5p giZa cng ngh%xR l 7nh v cng ngh%RFID hea hjn so t9o ra m0t trongnhZng s7n phqm cng ngh%m-i c hi%u qu7r6t cao c7v4mmt khoa hNc l2n th3c ti'n. M0ttrong nhZng 8iVm nki bQc cba cng ngh%ny chnh l kh7n)ng qu7n l. Do 8, v-i mongmu$n t)ng c1_ng kh7n)ng qu7n l xe ra, vo m0t cch hi%n 89i v hi%u qu7h.n (8mc bi%t l

trong qu trnh qu7n l xe ra vo cba h% th$ng giZ xe), nhm 84 xu6t chNn 84 ti H1TH5NG NH/N D%NG BI7N S5XE 8NG D"NG CNG NGH1X3L :NH lm84ti t$t nghi%p cba nhm.

1.2 MVc Tch nghin cXuXy d3ng 815c m0t m hnh nhQn d9ng biVn s$xe c.b7n eng dXng cng

ngh%xRl 7nh v cng ngh%RFID. Tn8, c7i ticn v hon chgnh 8Vc thVp dXngvo th3c tc.

v Tm hiYu cng nghNRFID Tkng quan v4cng ngh%RFID. Phn tch cc thnh ph,n cba h%th$ng RFID Tm hiVu tnh hnh eng dXng cng ngh%RFID

vTm hiYu giao thXc truyUn thng nZi ti[p RS232 v RS485 Khi ni%m v cc 8mc tr1ng cba cc chuqn giao ticp.

v Tm hiYu cng nghNx\l Mnh. Tkng quan v4xRl 7nh. Phn tch cc ph1.ng php xRl 7nh. Tm hiVu tnh hnh eng dXng cng ngh%xRl 7nh.

v Thi[t k[ph]n cXng. Tm hiVu yu c,u thict kcm9ch 8Nc RFID. Thict kcm9ch 8Nc transponder v giao ticp v-i my tnh. Thict kcm9ch chuyVn 8ki USB RS232.

v Thi[t k[ph]n mUm Thict kc ph,n m4m trung gian giao ticp giZa m9ch 8Nc v h% th$ng

my chb. Thict kcph,n m4m xRl 7nh.


10/68


GVHD : ThS. Nguy'n V)n Nga Ch1.ng 1: D2n nhQp

1.3$Zi tP^ng nghin cXu v ph_m vi nghin cXuv $Zi tP^ng nghin cXu :

ThiRFID, reader RFID, IC EM4095, vi 8i4u khiVn PIC16F877A Ngn ngZlQp trnh C++.

v Ph_m vi nghin cXu Wng dXng cng ngh%RFID . Thi cng KIT reader RFID sRdXng IC4095. Kct h5p eng dXng cng ngh%xRl 7nh v cng ngh%RFID 8Vthi cngh%th$ng nhQn d9ng biVn s$xe.

H%th$ng nhQn d9ng biVn s$xe nhQn d9ng 815c 8ng biVn s$xe ra vo. H9n chccba h%th$ng l m0t lc khng 8Nc 815c nhi4u thitag. i4u khiVn 815c thanh chrn khi xc nhQn 8ng biVn s$xe.

1.4 ngh`a khoa hKc v thbc tiEn cca TUtiQuyVn 8!n ny eng dXng nghin ceu l thuyct v4cng ngh%RFID cba cc anh ch`

cc kho tr1-c , tn8 kct h5p v-i cng ngh%xRl 7nh thict kc1 h%th$ng h%th$ng nhQnd9ng biVn s$xe 815c lQp trnh trn kicn thec v4vi 8i4u khiVn v xRl 7nh sRdXng ngnngZC, C++. V vQy nhm th3c hi%n 84ti hy vNng quyVn 8!n ny soticp tXc l ngu!nti li%u tham kh7o 8Vhon thi%n h%th$ng giZxe thng minh.

1.5 Tnh hnh nghin cXuHi%n nay m0t s$m hnh eng dXng RFID t9i Vi%t Nam: Gi7i php kiVm sot vo ra,

ch6m cng 8i%n tR, kiVm sot thang my 8ang 815c p dXng t9i cng ty TECHPRO Vi%tNam; Tr9m thu ph xa l0H N0i; H%th$ng kiVm sot bi 8dxe t380ng t9i h,m 8Qu xe tanh The Manor TP.HCM; Ngnh vQn chuyVn hQu c,n (logistics), kiVm sot ton b0hngha tnn.i s7n xu6t cho 8cn n.i tiu thXcu$i cng.

Hi%n nay trn cc di'n 8n 8i%n tRc r6t nhi4u ti li%u nghin ceu v4RFID gip chosinh vin d'dng ticp cQn cng ngh%ny. Thng qua cc di'n 8n ny nhm th3c hi%n 84ti nhQn th6y c r6t nhi4u thnh vin 8 th3c hi%n thict kc815c nhi4u h%th$ng eng dXngtrn th3c tcnh1qu7n l thng tin sinh vin, kha cRa,

V-i nhZng ti li%u thu thQp v kicn thec tch lly nhm th3c hi%n 84ti l3a chNn ngnngZC,C++ 8Vthict kcm0t eng dXng nh1nhQn d9ng biVn s$xe.

1.6 PhPRng php nghin cXuy l m0t 84ti kh hay v p dXng 815c vo th3c tcnh1ng trong th_i gian th3c

hi%n 8!n nhm th3c hi%n 84ti gmp r6t nhi4u kh kh)n khi thu thQp ngu!n ti li%u.Nhm th3c hi%n 84ti sRdXng hai ph1.ng php chbycu:

v Ph1.ng php tham kh7o ti li%u: Ngu!n ti li%u chb ycu bpng c7 ticng Anh v ticng Vi%t 815c tm kicm

trn m9ng internet. Tham kh7o ti li%u nghin ceu cba cc anh ch`n)m tr1-c lm 8!n 8Vl9i.

v Ph1.ng php th3c hnh: Thict kcv thi cng kit reader RFID 8Vd'dng nrm brt 815c l thuyct. LQp trnh cho vi 8i4u khiVn v lQp trnh xRl 7nh.


11/68


GVHD: ThS. Nguy'n V)n Nga Ch1.ng 2: Gi-i thi%u chung v4cng ngh%RFID

2.1 HNthZng RFID ( Radio Frequency Identification)Tn thng dXng cba cng ngh% ny l RFID (Radio Frequency Identification).

Transponder l nhZng t6m thi plastic c grn cc microchip b chg bpng m0t nRa h9t ct.Chng brt 815c cc tn hi%u sng radio v 8p eng bpng cch pht ra m s$nhQn di%n t1.ngeng. H,u nh1 t6t c7cc transponder khng dng ngu!n pin 8V cung c6p n)ng l15ng ho9t80ng m sRdXng n)ng l15ng tnsng radio kch ho9t 8Vho9t 80ng.

y l lo9i ph1.ng ti%n 8VnhQn di%n ng1_i homc vQt qua vi%c truy4n sng v tuycn.H%th$ng thu dZli%u nhQn di%n t380ng khng dy ny r6t ch trNng 8cn vi%c 8Nc v ghi thngtin m khng c,n ticp xc v l m0t lNai cng ngh% r6t hi%u qu7 trong mi tr1_ng s7n xu6tclng nh1cc mi tr1_ng khng thn thi%n khc khi m v9ch khng cn pht huy tc dXng815c nZa.

2.2 T]n sZho_t Tdng v Xng dVng tPRng Xng cca hNthZng RFID2.2.1 T]n sZho_t Tdng cca RFID

Transponder v reader giao ticp v-i nhau f cng m0t t,n s$. Do h% th$ng RFIDtruy4n nhQn v-i nhau thng qua sng v tuycn v kho7ng cch clng nh1kh7n)ng truy4nnhQn phXthu0c r6t nhi4u vo t,n s$chnh v vQy m cc h%th$ng RFID sRdXng r6t nhi4u

t,n s$khc nhau. Nh1ng theo th3c ti'n th ph9m vi t,n s$ thng dXng nh6t, 8 l t,n s$th6p (LF) (kho7ng 125kHz 150 kHz), t,n s$cao (HF) (10 15 MHz) v siu cao t,n(UHF) (850 950 MHz). V-i nhZng t,n s$khc nhau th sothch h5p v-i nhZng eng dXngkhc nhau.

DMi t]n T]n sZ Ph_m vi TKc tZi Ta TZc TdtruyUn deliNu

Gi reader

LF 125 t-i 135 kHz 25cm (150cm) H.i th6p Th6p

HF 13.56 Mhz 5cm (60cm) Cao Trung bnh

UHF 868 t-i 928 Mhz 3m (10m) Trung bnh R t cao

Bng 2.1Cc di t"n s$ho&t '(ng c)a h+th$ng RFID

2.2.2 8ng dVng cca hNthZng RFID trong mfi dMi t]n sZkhc nhauCc t,n s$khc nhau c cc 8mc tnh clng nh1s3t1.ng thch khc nhau cho nn n

ph h5p v-i m0t s$lsnh v3c eng dXng ring.V dX: tt,n s$th6p cc thisRdXng cng su6t t h.n v c kh7n)ng xuyn qua phi

kim t$t h.n, nh1ng chng c nh15c 8iVm l ph9m vi 8Nc thingrn th1_ng d1-i 0.5m.Cc thilm vi%c ft,n s$cao th c kh7n)ng 8i qua 815c nhZng vQt thVlm bpng kim

lo9i, nh1ng ph9m vi 8Nc cba chng clng chgkho7ng 1m.Cc t,n s$cao t,n UHF c ph9m vi 8Nc t$t h.n clng nh1c thVtruy4n dZli%u nhanh

v xa h.n so v-i t,n th6p v t,n cao (LF v HF), nh1ng chng c,n c cng su6t l-n h.n vkh7n)ng xuyn qua kim lo9i km. V vQy giZa reader v thiph7i khng c vQt c7n.


12/68



T,n s$ mc 8iVm Gi thnh Wng dXng

100-150KHz

- T$c 808Nc chQm- Xuyn qua cc vQt li%u phi kim

d'dng- Kho7ng cch 8Nc tnngrn 8cn

trung bnh

- Khng 8rt - i4u khiVn truynhQp

- KiVm k

10-15MHz

- T$c 808Nc trung bnh- Kho7ng cch 8Nc tnngrn 8cn

trung bnh

- Khng qua 8rt - i4u khiVn truynhQp

850-950MHz

- Kho7ng cch 8Nc l-n- T$c 808Nc nhanh- Yu c,u t,m nhn thung

- rt - H%th$ng nhQnd9ng v 8i4u khiVnvo ra cba xe c0.

- KiVm k hng hatr1-c khi vo kho.

2.4-2.8GHz

- Kho7ng cch 8Nc l-n- T$c 808Nc nhanh- Yu c,u t,m nhn thung

- rt - H%th$ng nhQnd9ng v 8i4u khiVns3vo ra cba xe c0

Bng2.2 B-ng t"n v cc /ng d2ng t03ng /ng c)a RFID

2.3 'u TiYm v nhP^c TiYm cca hNthZng RFID2.3.1 'u TiYm cca hNthZng RFID

v Du 8iVm cba h%thng RFID c thVchia ra 2 m$c th_i gian nh1sau : Hi%n t9i : nhZng 1u 8iVm ny c thVeng dXng tr3c ticp vo s7n phqm cng

ngh%ngy nay. T1.ng lai : NhZng 1u 8iVm ny c thV815c eng dXng trong th_i gian t-ihomc c thVt)ng c1_ng nhZng tnh n)ng nh1m0t cng ngh%hon thi%n cho

sau ny. S3cch ly ( khng ticp xc) : m0t tag c thV8Nc m khng c,n c m0t s3

ticp xc no giZa tag v 8,u 8Nc RFID. C kh7n)ng ghi dZli%u : c thVghi dZli%u ln tag RFID read-write nhi4u

l,n. Khng c,n nhn th6y : 8,u 8Nc RFID c thV8Nc 815c tag RFID m khng

c,n nhn th6y nhau. Ph9m vi 8Nc : Tag RFID c thV8Nc tnvi inch 8cn 100 feet (30.48 m). Dung l15ng l1u trZdZli%u : Tag RFID c thVl1u trZvi bytes dZli%u tn

m0t dung l15ng l-n dZli%u. Hdtr58Nc 8a knh : N cho php sRdXng m0t 8,u 8Nc 8V8Nc 815c nhi4u

tag trong vng ho9t 80ng cba n v-i th_i gian ngrn. Kh7n)ng thch eng : Tag RFID c thVduy tr ho9t 80ng trong 8i4u ki%n

mi tr1_ng t1.ng 8$i b6t l5i. Ho9t 80ng thng minh : Tag RFID ngoi vi%c mang v truy4n v dZli%u, n

cn 815c thict kc8Vth3c hi%n cc nhi%m vXkhc. 0chnh xc : c thV8Nc chnh xc 8cn 100%.


13/68



2.3.2 NhP^c TiYm cca hNthZng RFIDNhZng nh15c 8iVm hi%n t9i cba h%th$ng RFID bao g!m :

Km hi%u qu7v-i nhZng vQt chrn sng RF v nhZng vQt h6p thXsng RF:cng ngh%ngy nay lm vi%c khng hi%u qu7v-i nhZng vQt li%u ny, trongm0t s$tr1_ng h5p cn trfnn nguy hiVm.

?nh h1fng bfi cc ycu t$mi tr1_ng : 8i4u ki%n mi tr1_ng xung quanhtc 80ng m9nh 8cn eng dXng RFID.

Gi-i h9n 8Nc tag : m0t h9n chcl c bao nhiu tag 81.c 8Nc cng lc. ?nh h1fng nhi'u ph,n ceng : m0t gi7i php RFID c thVb`7nh h1fng tiu

c3c ncu ph,n ceng khng 815c lrp 8mt 8ng cch (nh1 v` tr v h1-nganten).

H9n chckh7n)ng chi ph$i n)ng l15ng sng RF : mmc d RFID khng c,nnhn th6y, c m0t gi-i h9n l n)ng l15ng RF c thV ticp cQn f80su baonhiu mmc d c thVxuyn qua vQt sng v-i RF.

Cng ngh%non-tri: mmc d cng ngh%RFID 8ang tr7i qua nhZng thay 8kinhanh chng nh1ng nhZng thay 8ki 8 bo hi%u s3b6t ti%n khi khng c7nhgic.

2.4 8ng dVng cca hNthZng RFID Qu7n l 8$i t15ng, nhn s3. KiVm sot vo ra ,ch6m cng 8i%n tR,kiVm sot thang my. Qu7n l hng ha bn litrong siu th`. Nghin ceu 80ng vQt hNc. Qu7n l hng ha trong x ngh`p, nh kho... Qu7n l xe c0qua tr9m thu ph. L1u trZthng tin b%nh nhn trong y khoa(mang theo ng1_i b%nh nhn 8mc bi%t

l b%nh nhn tm th,n). Lm h0chicu, cheng minh nhn dn ( MO). RFID trong xRph9t. RFID trong an ninh qu$c gia.


14/68


GVHD: ThS. Nguy'n V)n Nga Ch1.ng 3: NhZng 8mc tr1ng c.b7n cba cng ngh%RFID

3.1 Cc thnh ph]n cRbMn cca hNthZng RFIDCc thnh ph,n chnh trong h% th$ng RFID l thi, 8,u 8Nc (reader) v c. sf dZ

li%u. Tuy nhin, m0t h%th$ng RFID ton di%n bao g!m 4 thnh ph,n : ThiRFID (RFID tag, Transponder) 815c lQp trnh 8i%n tRv-i thng tin duy

nh6t. Cc 8,u 8Nc (Reader) homc c7m bicn (sensor) 8Vtruy v6n cc thi. Anten thu, pht sng v tuycn. Host computer server, n.i m my chbv h%th$ng ph,n m4m giao di%n

v-i h%th$ng 815c t7i. N clng c thVphn ph$i ph,n m4m trong cc reader v c7m bicn.C.sfh9t,ng truy4n thng l thnh ph,n brt bu0c, n l m0t tQp g!m c7hai m9ng c dyv khng dy v cc b0phQn kct n$i tu,n t38Vkct n$i cc thnh ph,n 8 li%t k ftrn v-inhau 8Vchng truy4n v-i nhau hi%u qu7.

Hnh 3.1 H+th$ng RFID ton di+n

3.2 Transponder3.2.1 GiQi thiNu tgng qut transponder

Thnh ph,n cba transponder bao g!m m0t anten dng kct n$i v-i reader v m0t conchip dng 8Vl1u trZdZli%u. DZli%u 815c 8Nc ghi thng qua m0t reader thi(reader RFID)m khng phX thu0c vo h1-ng hay v` tr chgc,n transponder npm trong vng phbsng(ph9m vi cba reader).

Hnh 3.2 Hnh d&ng c)a m(t transponder 'i4n hnh


15/68



Hnh 3.3 C6u trc bn trong m(t transponderB0nh-chip trong transponder c thVchea tn96 8cn 512 bit dZli%u nhi4u g6p 64

l,n m v9ch. Thng tin l1u trZtrn chip c thVthay 8ki 815c bfi s3t1.ng tc cba reader.

Dung l15ng l1u trZcao c thVcho php ta l1u trZnhi4u thng tin 8a d9ng cng m0t lc.Chip trn thi815c grn km v-i m0t anten chuyVn tn hi%u 8cn my 8Nc v my nychuyVn 8ki sng 8i%n tntntransponder cung c6p sang m0t d9ng m lin quan 8Vxc 8`nhthng tin v xRl c.sfdZli%u trn my tnh do ng1_i 8i4u hnh qu7n l gim st.

Cc transponder r6t mvng v c kch cw vna ph7i t1.ng 81.ng nh1 m0t thi tndXng bnh th1_ng v n 8.n gi7n clng chgc,n m0t anten v m0t diode

3.2.2 Phn lo_i transponderTy thu0c vo chec n)ng v cc chuqn m transponder 815c phn lo9i thnh nhi4u

lo9i khc nhau : ThithX80ng ( Passive tag). Thitch c3c (Active tag). Thibn thX80ng (Semi-Pasive tag).

Phn lo9i theo kh7n)ng ghi/ 8Nc dZli%u : Thichg8Nc ( Read Only). Thicho php ghi m0t l,n, 8Nc nhi4u l,n (Write once Read many, WORM). Thighi 8Nc (Write - Read)

3.2.2.1 ThhthVTdng (Passive tag)Khng c ngu!n 8i%n bn trong. Sng v tuycn pht ra tn reader so truy4n m0t

dng 8i%n nhv8b8Vkch ho9t h%th$ng m9ch 8i%n trong thigip n gRi l9i tn hi%u h!i8p.

C thVtruy4n m s$nhQn d9ng v l1u trZm0t s$thng tin v48$i t15ng 815c nhQn

d9ng. C kch th1-c r6t nhvv mvng h.n m0t t_gi6y bnh th1_ng, do vQy n c thV815cc6y vo d1-i da.

C tuki thNr6t cao.T,m ho9t 80ng : tn10 cm 8cn vi mt, ty theo t,n s$sRdXng.Gi thnh : kho7ng 0,2 8-la.


16/68



Hnh 3.4 S3'7kh$i c)a m(t th8th2'(ng

3.2.2.2

ThhchcTdng (Active tag)15c tch h5p m0t ngu!n 8i%n gip n t3 gRi tn hi%u 8cn reader. C1_ng 80 tnhi%u cba lo9i thiny, do vQy m9nh h.n tn hi%u cba thithX80ng, cho php n ho9t 80ngc hi%u qu7h.n trong mi tr1_ng n1-c (trong c.thVcon ng1_i hay 80ng vQt) hay kim lo9i(xe c0, container).

M0t s$thicn 815c tch h5p cc b0c7m bicn 8V8o 80qm, 80rung, 80phng x9,nh sng, nhi%t 80...

Tuki thNcba pin ln 8cn 10 n)m.T,m ho9t 80ng: vi tr)m mt, ty theo t,n s$sRdXng.Gi thnh : 10-25 8 la.

ThhthVTdng Thhtch cbc

Ngu!n cng su6t L6y tnbn ngoi (Do reader cungc6p)

Bn trong(Pin)

Kh7n)ng 8Nc thiChgtrong ph9m vi bao phbcbareader, thng th1_ng c thVln t-i3m.

C thVpht tn hi%uqua m0t kho7ng cchkh xa, th1_ng th cthVln t-i 100m.

N)ng l15ngM0t thithX80ng 815c c6p n)ngl15ng chgkhi n npm trong ph9mvi cba reader.

M0t thitch c3c thlun c n)ng l15ng.

C1_ng 80tr1_ng

8i%n tn

Cao, khi thitnl6y cng su6t tntr1_ng 8i%n tn815c cung c6p bfi

reader.

Th6p, khi thicho phptn hi%u sRdXng ngu!n

pin n0i b0.

Tuki thN R6t cao.D1-i 5 n)m, v b`gi-ih9n bfi tuki thNcba

pin.L15ng dZli%u l1utrZ

L1u trZdZli%u c gi-i h9n,th1_ng kho7ng 128 bytes.

C thVl1u trZm0tl15ng dZli%u l-n h.n.

Bng 3.1 So snh th8th2'(ng v th8tch c9c3.2.2.3 Thhbn thVTdng (Semi Passive tag)


17/68



Thibn tch c3c c m0t ngu!n n)ng l15ng bn trong (chung h9n l b0pin) v 8i%ntRhNc bn trong 8Vth3c thi nhZng nhi%m vXchuyn dXng. Ngu!n bn trong cung c6p n)ngl15ng cho thi ho9t 80ng. Tuy nhin trong qu trnh truy4n dZ li%u, thi bn tch c3c sRdXng ngu!n tnreader. Thibn tch c3c 815c gNi l thic hdtr5pin (battery-assisted tag).

Hnh 3.5 : C6u trc c)a th8bn th2'(ng$i v-i lo9i thiny, trong qu trnh truy4n giZa thiv reader th reader lun truy4n

tr1-c r!i 8cn thi. T9i sao sRdXng thibn tch c3c m khng sRdXng thithX80ng ? Bfi vthibn tch c3c khng sRdXng tn hi%u cba reader nh1thithX80ng, n t3kch 80ng, nc thV8Nc fkho7ng cch xa h.n thithX80ng. Bfi v khng c,n th_i gian ticp n)ng l15ngcho thibn tch c3c, thic thVnpm trong ph9m vi 8Nc cba reader t h.n th_i gian 8Nc quy8`nh (khng gi$ng nh1thithX80ng). V vQy ncu 8$i t15ng 815c grn thi8ang di chuyVn ft$c 80cao, dZli%u thic thVv2n 815c 8Nc ncu sRdXng thibn tch c3c. Thibn tch c3cclng cho php 8Nc t$t h.n ngay c7khi grn thibpng nhZng vQt li%u chrn t,n s$v tuycn(RF-opaque v RF-absorbent). S3c mmt cba nhZng vQt li%u ny c thVng)n khng chothithX80ng ho9t 80ng 8ng d2n 8cn vi%c truy4n dZli%u khng thnh cng. Tuy nhin, 8ykhng ph7i l v6n 84kh kh)n 8$i v-i thibn tch c3c.

Ph9m vi 8Nc cba thibn tch c3c c thVln 8cn 100 feet (x6p xg30.5 m) v-i 8i4uki%n l t1fng bpng cch sRdXng m hnh tn x98 815c 8i4u chc(modulated back scatter)

(trong UHF v sng vi ba).3.2.2.4 ThhchiTKc (Read Only)ThiRO c thV815c lQp trnh (tec l ghi dZli%u ln thiRO) chgm0t l,n. DZli%u c

thV815c l1u vo thit9i x nghi%p trong lc s7n xu6t. Vi%c ny 815c th3c hi%n nh1sau: ccc,u ch ring litrn vi m9ch cba thi815c grn c$8`nh bpng cch sRdXng chm tia laser.Sau khi th3c hi%n xong, khng thVghi 8 dZ li%u ln thi815c nZa. Thiny 815c gNi lfactory programmed. Nh s7n xu6t lo9i thiny so81a dZli%u ln thiv ng1_i sRdXng thikhng thV8i4u chgnh 815c. Lo9i thiny chg t$t 8$i v-i nhZng eng dXng nhvm khngth3c tc8$i v-i quy m s7n xu6t l-n homc khi dZ li%u cba thic,n 815c lm theo yu c,ucba khc hng d3a trn eng dXng. Lo9i thiny 815c sR dXng trong cc eng dXng kinhdoanh v hng khng nhv.

3.2.2.5 Thhcho php ghi mdt l]n, TKc nhiUu l]n (WORM)ThiWORM c thV815c ghi dZli%u m0t l,n, m th1_ng th khng ph7i 815c ghibfi nh s7n xu6t m bfi ng1_i sRdXng thingay lc thi c,n 815c ghi. Tuy nhin trongth3c tcth c thVghi 815c vi l,n (kho7ng 100 l,n). Ncu ghi qu s$l,n cho php, thicthVb`ph hvng vsnh vi'n. ThiWORM 815c gNi l field programmable. Lo9i thiny cgi c7v hi%u su6t t$t, c an ton dZli%u v l lo9i thiphkbicn nh6t trong lsnh v3c kinhdoanh ngy nay.


18/68



3.2.2.6 ThhTKc-ghi(Read - Write)ThiRW c thVghi dZli%u 815c nhi4u l,n, kho7ng tn10.000 8cn 100.000 l,n homc

c thVh.n nZa. Vi%c ny 8em l9i l5i ch r6t l-n v dZli%u c thV815c ghi bfi reader homcbfi thi(ncu l thitch c3c). ThiRW g!m thict b`nh-Flash v FRAM 8Vl1u dZli%u. ThiRW 815c gNi l field programmable homc reprogrammable. S3an ton dZli%u l m0t thchthec 8$i v-i thiRW. Thm vo nZa l lo9i thiny th1_ng 8rt nh6t. ThiRW khng 815csRdXng r0ng ri trong cc eng dXng ngy nay, trong t1.ng lai c thVcng ngh%thiphttriVn th chi ph thigi7m xu$ng.

3.2.3 Cc d_ng cju trc cca transponder D_ng Disks v d_ng coins

D9ng c6u trc phkbicn nh6t 815c gNi l disk homc coin, m0t transponder timvo trong m0t vv trn, v-i gi-i h9n 81_ng knh tn vi millimetres 8cn 10 centimetres .Th1_ng c m0t ldtrn ftrung tm 8V 8`nh v`.

Hnh 3.6 Cc d&ng c6u trc khc nhau c)a disk transponder D_ng glass housing

D9ng transponder ny 815c eng dXng trong cc h%th$ng nhQn d9ng 80ng vQt. N815c tim vo d1-i l-p da cba 80ng vQt.

Hnh 3.7 C6u trc c)atransponder th)y tinhChip RFID 815c 8mt trong cc $ng thby tinh, kch th1-c tn12 -32 mm. Cu0n dy

anten cba transponder c kch th1-c kho7ng 0.03mm v qu6n quanh m0t li ferit srt.

Hnh 3.8 C6u trc bn trong c)atransponder th)y tinh D_ng plastic housing


19/68



D9ng plastic housing 815c pht triVn trong cc eng dXng y4u c,u tnh c.hNc cao.D9ng ny c thVd'dng tch h5p vo trong cc s7n phqm khc nhau, v dXnh1cha khaxe t .

Hnh 3.9 D&ng th8nh9a,sn ph:m c)a Philips Electronics

D_ng key v key fobs.Cc transponder 815c tch h5p vo trong cc cha kha cho cc h% th$ng c$8`nh

homc cc eng dXng kha cRa yu c,u 80an ton cao. Trong cc eng dXng ny, transponder8ng vai tr lm cha kha v reader lm nhi%m vXkha.

Hnh 3.10 : Transponder d&ng key, sn ph:m c)a Intermarketing

D_ng thhthng minh khng ti[p xc

Hnh 3.11 Transponder d&ng th8khng ti;p xcD9ng thithng minh 815c pht triVn d3a trn thitn dXng , thi8i%n tho9i. M0t 1u

8iVm cba d9ng thiny l di%n tch cu0n dy l.n nn n c kh7n)ng lm t)ng ph9m vi ho9t80ng cba h%th$ng RFID.

D_ng Coil-on-chipTrong cc d9ng c6u trc cba transponder 815c kVtrn, cc transponder c hai ph,n

ring bi%t 8 l cu0n dy cba transponder 8ng vai tr nh1 l m0t angten, v chiptranspoder. D1-i 8y l d9ng transponder m chng ta 8 tch h5p chip v cu0n dy cbatransponder. V vQy m d9ng transponder ny th1_ng c kch th1-c r6t nhvkho7ng 3mm.

Hnh 3.12 Transponder d&ng coil-on-chipNgoi ra cn c cc d9ng c6u trc khc nh1: d9ng smartlabel, d9ng clock.


20/68



3.3 $]u TKc (Reader)M0t reader 8iVn hnh m0t module t,n s$v tuycn (my pht v my thu) l m0t

8.n v`8i4u khiVn v l ph,n tRkct n$i 8cn b0pht 8p. Ngoi ra, cc reader cn 815c grnv-i m0t giao di%n bksung (RS232,RS485) 8Vchng c thVchuyVn dZli%u 8Nc 8cn cch%th$ng khc (PC, h%th$ng 8i4u khiVn robot)

Reader RFID 815c gNi l vQt tra hvi (interrogator), l m0t thict b`8Nc v ghi dZli%u cc transponder t1.ng thch. Ho9t 80ng ghi dZli%u ln thibpng reader 815c gNi l t9othi. Qu trnh t9o thiv kct n$i thiv-i m0t 8$i t15ng 815c gNi l 81a thivo ho9t 80ng(commissioning the tag).

Reader l h% th,n kinh trung 1.ng cba ton h% th$ng, ph,n ceng RFID thict lQpvi%c truy4n v-i thnh ph,n ny v 8i4u khiVn n, l thao tc quan trNng nh6t cba b6t kxth3c thVno mu$n lin kct v-i th3c thVcba ph,n ceng ny.

M0t reader c c6u trc layout nh1sau:

Hnh 3.13 C6u trc layout c3bn c)a m(t readerCc thnh ph,n chnh cba reader bao g!m:

My pht (Transmitter) My thu (Recever) Vi m9ch (Microprocessor) B0nh- Knh vo/ra 8$i v-i cc c7m bicn, c.c6u truy4n 80ng 8,u tn, b7ng tn hi%u bo bn

ngoi (mmc d ni 8ng ra 8y l nh1ng thnh ph,n khng brt bu0c, chng h,u nh1lun815c cung c6p v-i m0t reader th1.ng m9i).

M9ch 8i4u khiVn (c thVn 815c 8mt bn ngoi). M9ch truy4n thng. Ngu!n n)ng l15ng

3.3.1 Cc thnh ph]n chnh cca readerv My pht

My pht cba reader truy4n ngu!n AC v chu kxxung 8!ng h!qua anten cba n8cn thitrong ph9m vi 8Nc cho php, n ch`u trch nhi%m gRi tn hi%u cba reader 8cn mitr1_ng xung quanh v nhQn l9i 8p eng cba thiqua anten cba reader.v My thu


21/68



My thu nhQn tn hi%u t1.ng t3tnthiqua anten cba m9ch 8Nc 8Vn truy4n thngv-i thit1.ng thch v-i n. N th3c hi%n vi%c gi7i m v kiVm tra ldi tn hi%u nhQn t1.ng t3nhQn tnmy thu.v BdnhQ

B0nh-dng l1u trZdZ li%u nh1cc tham s$c6u hnh reader v m0t b7n k khaicc l,n 8Nc. V vQy ncu vi%c kct n$i giZa reader v h%th$ng m9ch 8i4u khiVn/ph,n m4m b`hvng th t6t c7dZli%u thi8 8Nc khng b`m6t.v Cc knh nhkp/xujt cca cc cMm bi[n, cRcju truyUn Tdng T]u tl

v bMng tn hiNu TiNn bo bn ngoiCc reader khng c,n bQt su$t. Cc thic thVchgxu6t hi%n lc no 8 v r_i khvi

m9ch 8Nc mi cho nen vi%c bQt reader su$t sogy lng ph n)ng l15ng. Thm nZa l gi-ih9n vna 84cQp f trn clng 7nh h1fng 8cn chu kxlm vi%c cba reader. Thnh ph,n nycung c6p m0t c.chcbQt v trt reader ty thu0c vo cc s3ki%n bn ngoi. C m0t s$lo9ic7m bicn nh1c7m bicn v4nh sng homc s3chuyVn 80ng 8Vpht hi%n cc 8$i t15ng 815cgrn thitrong ph9m vi 8Nc cba reader. C7m bicn ny cho php reader bQt ln 8V8Nc thi.Thnh ph,n ny clng cho php reader cung c6p xu6t cXc b0ty thu0c vo m0t s$8i4u ki%nqua m0t b7ng tn hi%u 8i%n bo (chung h9n, bo bpng m thanh) homc c.c6u truy4n 80ng

8,u tn(chung h9n, mfhomc 8ng van an ton, di chuyVn m0t cnh tay robot,)v M_ch TiUu khiYn

M9ch 8i4u khiVn l m0t th3c thVcho php th3c thVbn ngoi l con ng1_i homcch1.ng trnh my tnh giao ticp, 8i4u khiVn cc chec n)ng cba reader, 8i4u khiVn b7ng tnhi%u 8i%n bo v c.c6u truy4n 80ng 8,u tnkct h5p v-i reader ny. Th1_ng th cc nh s7nxu6t h5p nh6t thnh ph,n ny vo reader (nh1ph,n m4m h%th$ng (firm ware)).v Giao diNn truyUn thng

Thnh ph,n giao di%n truy4n thng cung c6p cc l%nh truy4n 8cn reader, n chophp t1.ng tc v-i cc th3c thVbn ngoi qua m9ch 8i4u khiVn, 8Vtruy4n dZli%u cba n,nhQn l%nh v gfi l9i 8p eng. Thnh ph,n giao di%n ny clng c thVxem l m0t ph,n cbam9ch 8i4u khiVn homc l ph1.ng ti%n truy4n giZa m9ch 8i4u khiVn v cc th3c thV bnngoi. Th3c thVny c nhZng 8mc 8iVm quan trNng c,n xem n nh1m0t thnh ph,n 80c

lQp. Reader c thVc m0t giao di%n tu,n t3. Giao di%n tu,n t3 l lo9i giao di%n phkbicnnh6t nh1ng cc reader thch%sau so815c pht triVn giao di%n m9ng thnh m0t tnh n)ngchuqn. Cc reader phec t9p c cc tnh n)ng nh1t3pht hi%n bpng ch1.ng trnh eng dXng,c grn cc web server cho php reader nhQn l%nh v trnh by kct qu7dng m0t trnh duy%tweb chuqn.

v Ngumn nIng lP^ngThnh ph,n ny cung c6p ngu!n n)ng l15ng cho cc thnh ph,n cba reader. Ngu!n

n)ng l15ng 815c cung c6p cho cc thnh ph,n ny qua m0t dy d2n 8i%n 815c kct n$i v-im0t ng ra bn ngoi thch h5p.3.3.2 Phn lo_i m_ch TKc

Reader 815c phn lo9i chbycu theo tiu chuqn l giao di%n m reader cung c6p chovi%c truy4n thng. Trong tiu chuqn ny, reader c thV815c phn lo9i ra nh1sau:

Serial reader Network readervSerial reader Reader nZi ti[p

Serial reader sRdXng lin kct serial 8Vtruy4n v-i m0t eng dXng. Reader kct n$i 8cnckng serial cba my tnh dng kct n$i tu,n t3RS232 homc RS485. C7hai lo9i kct n$i ny84u c gi-i h9n trn v4chi4u di cp sRdXng kct n$i reader v-i my tnh. Chuqn RS485cho php cp di h.n chuqn RS232.


22/68



Du 8iVm cba serial reader l c 80tin cQy cao h.n network reader. V vQy sRdXngreader lo9i ny 815c khuycn khch nhpm lm t$i thiVu s3phXthu0c vo m0t knh truy4n.

Nh15c 8iVm cba serial reader l phXthu0c vo chi4u di t$i 8a cba cp sRdXng 8Vkct n$i m0t reader v-i my tnh. Thm nZa, th1_ng th trn m0t my chbth s$ckng serial

b` h9n chc. T$c 80 truy4n dZ li%u serial th1_ng th6p h.n t$c 80 truy4n dZ li%u m9ng.NhZng nhn t$ny d2n 8cn chi ph b7o d1wng cao h.n v th_i gian chct 8ng kV.

v Network reader Reader m_ngNetwork reader kct n$i v-i my tnh sRdXng c7m9ng dy v khng dy. Th3c tc,

reader ho9t 80ng nh1thict b`m9ng.Du 8iVm cba network reader l khng phX thu0c vo chi4u di t$i 8a cba cp kct

n$i reader v my tnh. SRdXng t my chbh.n so v-i serial reader. Thm nZa l ph,nm4m h%th$ng cba reader c thV815c cQp nhQt tnxa qua m9ng.

Nh15c 8iVm cba network reader l vi%c truy4n khng 8ng tin cQy bpng serialreader.3.3.3 CRch[truyUn cRbMn giea thhv reader

Ty thu0c vo lo9i thi, vi%c truy4n giZa reader v thic thVtheo m0t trong nhZngcch sau:

Modulate backscatter. tn x98i4u chc KiVu my pht (transmitter type)Tr1-c khi nghin ceu su vo lo9i truy4n thng, ta ph7i hiVu 815c khi ni%m near

field (tr1_ng g,n) v far field (tr1_ng xa).Ph9m vi giZa anten cba reader v m0t b1-c sng cba sng RF 815c pht bfi anten

815c gNi l near field. Ph9m vi ngoi b1-c sng cba sng RF 8 pht ra tnanten cba readergNi l far field. Cc h%th$ng RFID thX80ng ho9t 80ng fb)ng t,n LF v HF sRdXng vi%ctruy4n thng near field trong khi b)ng t,n UHF v sng vi ba sRdXng far field. C1_ng 80tn hi%u trong truy4n thng near field ycu 8i lQp ph1.ng kho7ng cch tnanten cba reader.Trong far field, n gi7m 8i bnh ph1.ng kho7ng cch tnanten cba reader. Cho nn truy4nthng far field 815c kct h5p v-i ph9m vi 8Nc di h.n truy4n thng near field.

Hnh 3.14 C3ch;truyng g"n, tr0>ng xa gi@a th8v readerTicp theo so snh vi%c 8Nc thiv ghi thi. Vi%c ghi thim6t nhi4u th_i gian h.n vi%c

8Nc thitrong cng 8i4u ki%n v ho9t 80ng ghi g!m nhi4u b1-c, bao g!m vi%c xc minh ban8,u, xa dZ li%u cn t!n t9i trn thi, ghi dZli%u m-i ln thi. V giai 8o9n xc minh l,ncu$i. Thm nZa l dZli%u 815c ghi trn thitheo kh$i bpng nhi4u b1-c. V vQy vi%c ghi thic thVm6t c7tr)m giy m-i hon thnh cng v-i vi%c t)ng kch th1-c dZli%u. Ng15c l9i,c m0t s$thic thV815c 8Nc trong kho7ng th_i gian ny v-i cng reader. Vi%c ghi thil


23/68



qu trnh d'b`7nh h1fng c,n 8mt thig,n anten cba reader h.n kho7ng cch 8Nc t1.ngeng. Vi%c 8mt g,n nhpm cho php anten cba thic thVnhQn 815c 8bn)ng l15ng tntn hi%uanten cba reader 8Vc6p ngu!n cho vi m9ch cba n gip n c thV th3c thi cc l%nh ghi.

Nhu c,u n)ng l15ng 8$i v-i qu trnh ghi th1_ng cao h.n qu trnh 8Nc.v Modulated backscatter TiUu ch[tn x_

Vi%c truy4n modulater p dXng cho c7 thi thX80ng v bn tch c3c. Trong kiVutruy4n thng ny, reader gRi 8i tn hi%u RF sng lin tXc (continuos wave CW) g!m cngu!n AC v tn hi%u xung cho thicng t,n s$sng mang (carrier frequency t,n s$mreader ho9t 80ng). Nh_vi%c kct n$i (nghsa l c.chctruy4n n)ng l15ng giZa reader v thi)m anten cba thicung c6p ngu!n 8i%n cho vi m9ch. Tnkch thch th1_ng m chgvi%c vim9ch cba thithX80ng nhQn n)ng l15ng tntn hi%u cba reader 8Vt3ticp sinh l3c. Vi m9chc,n kho7ng 1.2V tntn hi%u cba reader 8Vticp sinh l3c 8$i v-i vi%c 8Nc. Cn 8$i v-i vi%cghi th vi m9ch th1_ng c,n kho7ng 2.2V tn tn hi%u cba reader. Hi%n nay, vi m9ch 8i4uchgnh thay 8ki tn hi%u nhQp thnh m0t chudi m hnh mf, trt trnh by dZli%u cba n vtruy4n n trfl9i. Khi reader nhQn tn hi%u 8 8i4u chc, n gi7i m m hnh v thu 815c dZli%u thi.

V vQy trong m hnh truy4n modulated backscatter, reader lun talks tr1-c sau8 m-i t-i thi. ThisRdXng m hnh ny khng thVtruy4n khi khng c mmt reader v n

phXthu0c hon ton vo n)ng l15ng cba reader 8Vtruy4n dZli%u cba n.

Hnh 3.15 C3ch;truy


24/68



Hnh 3.17 C3ch;truy


25/68



trong thict kcv d7i t,n h%th$ng RFID sRdXng. ThinhQn sng truy4n tnreader v nh_b0chuyVn 8ki sang DC v nh_b08i4u chc8VnhQn chudi bit tnreader truy4n t-i. Ticp 8cnthigRi sng mang chea dZli%u pht 8cn reader. Sau 8 815c 8i4u chc(gi7sRdng QAM)l m0t s$phec v 815c xcp vo biVu 8!chm sao theo quy luQt m Gray trn 2 trXc Re(th3c) v Im(7o). V`tr cba mdi 8iVm tn hi%u (s$phec) trn biVu 8!chm sao ph7n nhthng tin v4bin 80v pha cba cc sng mang. Qu trnh bicn 8ki FFT sobicn 8ki cc s$

phec biVu di'n cc sng mang trong mi4n t,n s$ thnh cc s$ phec biVu di'n cc sngmang trong mi4n th_i gian r_i r9c. Trong th3c tccc thnh ph,n Re v Im 815c biVu di'n

bpng chudi nh`phn 815c b08i4u chcIQ sRdXng 8V8i4u chcsng mang clng 815c biVudi'n bpng m0t chudi nh`phn. Chudi nh`phn sau 8i4u chcIQ 815c bicn 8ki DA 8VnhQn815c tn hi%u trong b)ng t,n c.b7n. Qu trnh xRl fpha thisoth3c hi%n biVn 8ki FFT8V t9o cc 8iVm 8i4u chcphec cba tnng sng mang phX trong symbol OFDM (b7n ch6tcba qu trnh t9o tn hi%u OFDM l phn tch chudi bit 8,u vo thnh cc sng mang 8815c 8i4u chc theo m0t kiVu no 8 trong mi4n th_i gian lin tXc), sau khi gi7i 8`nh v`(Demapping) xc 8`nh biVu 8!bit t1.ng eng cc tkh5p bit 815c c0ng l9i 8Vkhi phXcdng dZli%u 8 truy4n.

Hnh 3.19 Qu trnh truy


26/68



tr9m chb, trong khi reader 8ng vai tr nh1l tr9m t-, chgho9t 80ng khi l%nh ghi/8Nc nhQn815c tnph,n m4m eng dXng.

Hnh 3.20 Nguyn l Master Slave gi@a ph"n m


27/68



3.7.4 Yu c]u vUkhMnIng bdnhQKch cwcba dZli%u 815c quyct 8`nh bfi kh7n)ng l1u trZcba b0nh-. Dung l15ng

b0nh-7nh h1fng 8cn yu c,u v4l15ng thng tin. DZli%u chbycu 815c l1u trZtrong c.sfdZ li%u cba my tnh 8i4u khiVn. Ncu dZ li%u c,n ghi ln transponder th ta c,n c b0nh-EEPROM homc RAM.

Cc b0nh-EEPROM chbycu 815c sRdXng trong cc h%th$ng kct n$i c7m eng,dung l15ng b0nh-kho7ng 16 byte 8cn 8 Kbyte.

B0nh-RAM v-i pin hd tr5chbycu dng cho sng ngrn dung l15ng npm trongkho7ng 256 byte 8cn 64 Kbyte.3.8Sbm ha (coding) v sbTiUu bi[n (Modulation)

Hnh 3.21 D@li+u v dng d@li+u trong h+th$ng truy


28/68



sang mec cao. M Manchester th1_ng 815c sRdXng 8Vtruy4n dZli%u tntransponder 8cnreader.

Hnh 3.23 : M Manchester+ M RZ 8.n c3c, m0t s$1 nh`phn 89i di%n cho m0t tn hi%u fmec cao trong

th_i gian nRa chu kx8,u tin, v m0t s$0 nh`phn 89i di%n cho m0t tn hi%u fmec th6ptrong ton b0th_i gian cn l9i cba chu kx.

Hnh 3.24 M RZ '3n c9c+ M DBP, m0t s$0 nh`phn 815c m ha bfi s3chuyVn 8ki tn hi%u tnmec

ny sang mec khc trong m0t nRa chu kx, v m0t s$1 nh`phn 815c m ha bfi ph,ncn l9i cba chuyVn 8ki. H.n nZa, mec tn hi%u b`87o ng15c fth_i 8iVm ban 8,u cba mdikho7ng th_i gian trch m2u, v vQy tn hi%u m2u c thVd'dng 815c khi phXc fb0nhQn.

Hnh 3.25 M DBP

+ M Miller, m0t s$ 1 nh` phn 89i di%n bfi m0t s3 chuyVn 8ki mec tn hi%utrong m0t nRa th_i gian trch m2u, m0t s$0 nh`phn 89i di%n bfi s3ko di cba mec1 sang kho7ng th_i gian trch m2u ticp theo. M0t chuki cc con s$0 t9o nn m0t s3chuyVn 8ki fth_i 8iVm brt 8,u cba m0t th_i gian trch m2u, v vQy m tn hi%u m2u c thVd'dng 815c khi phXc fb0nhQn.

Hnh 3.26 M Miller

+ M Miller bicn thV, trong d9ng biVn thVny cba m Miller mdi s3 chuyVn 8ki815c thay bpng m0t xung tiu c3c.D9ng m ny r6t ph h5p v-i cc h%th$ng RFID kctn$i c7m eng 8Vtruy4n dZli%u tnreader t-i transponder.

Hnh 3.27 M Miller (d&ng bi;n th4)


29/68


GVHD : ThS. Nguy'n V)n Nga Ch1.ng 5 : Giao thec truy4n thng qua RS232 v RS485

5.1 Chunn RS232Ghp n$i qua ckng n$i tcp RS-232 l m0t trong nhZng kOthuQt 815c sRdXng r0ng ri

nh6t 8Vghp n$i cc thict b`ngo9i vi v-i my tnh. Qua ckng n$i ticp c thVghp n$i chu0t,modem, thQm ch c7my in (v dXcc lo9i my in Apple), b0bicn 8ki A/D, cc thict b`8ol1_ng S$l15ng v chbng lo9i cc thict b`ngo9i vi ghp n$i qua ckng n$i ticp 8eng hng

8,u trong s$cc kh7n)ng ghp n$i v-i my tnh. Cch ghp n$i ny sRdXng ph1.ng phptruy4n thng theo kiVu n$i ticp, nghsa l trong m0t th_i 8iVm chgc m0t bit 815c gRi 8i dNctheo m0t 81_ng truy4n. Chuqn RS-232 dng m0t 81_ng d2n 8Vtruy4n dZli%u v m0t 81_ngd2n khc 8VnhQn dZli%u.

5.1.1 Vi nt vUngumn gZc:Chuqn RS-232 (RS = Recommended Standard) khi m-i chgl chuqn khng chnh thec

8 815c nhi4u cng ty my tnh v thict b`8o l1_ng ch6p nhQn. Sau 8, Hi%p h0i Cc nhcng nghi%p i%n tR(EIA: The Electronic Industries Association) 8 xy d3ng thnh m0t tiuchuqn chnh thec vo n)m 1962. ng ticc l tiu chuqn ny chg cho php sR dXng 81_ngtruy4n ngrn v-i t$c 80bit th6p, th dXnh1t$c 80bit l 19600 bps (bits per second) v kho7ngcch c3c 89i l 20 mt. Cc tiu chuqn truy4n thng n$i ticp ra 8_i sau nh1RS- 422, RS-449

v RS-485 cho php truy4n trn 81_ng cp r6t di v-i t$c 80bit cao. Chung h9n RS-422 chophp truy4n v-i t$c 80ln 8cn 10 Mbps v kho7ng cch h.n 1000 mt, 8!ng th_i c thVsRdXng cp xorn 2 s5i, cp 8!ng trXc v cp quang.

C hai phin b7n RS-232 815c l1u hnh trong th_i gian t1.ng 8$i di l RS-232B vRS-232C. Cho 8cn nay, RS-232B l phin b7n 8 cl, nay 8 t 815c sRdXng. Cn RS-232Chi%n v2n cn t!n t9i v th1_ng 815c gNi ngrn gNn l chuqn RS-232 (nh1ng 8y khng ph7i l

phin b7n ban 8,u n)m 1962). tm0t s$n1-c Ty u, ng1_i ta cn gNi chuqn ghp n$i RS-232 l chuqn V24.

EIA 8 cng b$ tiu chuqn RS-232C v-i nd l3c nhpm t9o ra kh7n)ng ghp n$i ccthict b`do nhi4u nh s7n xu6t lm ra m khng 8i hvi c m0t tiu chuqn 8mc bi%t cho tnngtr1_ng h5p.

Ngy nay, h,u hct cc my tnh 84u 815c trang b`m0t hay vi ckng n$i ticp RS-232,c thV l lo9i 9 chn homc 25 chn ty 8_i my v ty mainboard hd tr5. Vi%c thict kcgiaoticp v-i ckng RS-232 clng t1.ng 8$i d'dng, 8mc bi%t khi chNn chc80ho9t 80ng l khng8!ng b0v d$c 80truy4n dZli%u th6p. Cc m9ch 8i%n tch h5p c7b0pht v b0nhQn RS-2328 815c cc nh s7n xu6t khc nhau thict kcv chct9o r6t thnh cng, v dXnh1Motorola,

National SemiconductorCc chip b0 pht RS-232 ticp nhQn mec 8i%n p TTL f l$i vo v bicn 8ki chng

thnh cc mec dnh ring cho RS-232 8Vtruy4n. Cc chip b0nhQn th lm vi%c ng15c l9i: ticpnhQn tn hi%u l$i vo theo chuqn RS-232 v bicn 8ki sang cc mec TTL t1.ng eng. Cc b0

phQn ny 84u npm trn b7n m9ch chnh homc trn m0t card vo/ra.

5.1.2 Cc Toc trPng TiNn5.1.2.1 Cc mXc TiNn p TPpng truyUnTiu chuqn RS-232 8,u tin ngay tnkhi ra 8_i 8 mang vildi th_i cba cc chuqn TTL.L do l chuqn RS-232 v2n sRdXng cc mec 8i%n p t1.ng thch TTL 8Vm t7cc mec logic0 v 1, gi$ng nh1tr1_ng h5p ckng my in (ckng song song). Ngoi mec 8i%n p, tiu chuqnclng c$8`nh cc gi trtrfkhng t7i 815c 86u vo bus cba b0nhQn v cc trfkhng ra cba

b0pht.Cc mec 8i%n p cba hai tiu chuqn RS-232 c7i ticn l RS-232B v RS-232C 815c m

t7trong b7ng sau:


30/68



Chuqn Mec logic 0 Mec logic 1RS-232B +5V 8cn +25V -25V 8cn -5VRS-232C +3V 8cn +12V -12V 8cn -3V

Bng 5.1 Chu:n 'i+n p RS-232Ghi ch: Cc mec 8i%n p trong ph9m vi tn-3V ... +3V l tr9ng thi chuyVn ticp, cn

trong cc ph9m vi -5V ... -3V v +3V ... +5V khng 815c xc 8`nh v sod2n 8cn cc kct qu7khng thVd3tnh tr1-c (8$i v-i chuqn RS-232B).

5.1.2.2 Cc Toc trPng khc (dng cho chunn RS-232C l chunn thngdVng nhjt ngy nay)

Ngoi 8mc tr1ng v4mec 8i%n p 81_ng truy4n, chuqn RS-232C cn c cc 8mc tr1ngkhc nh1sau:

Trfkhng t7i v4pha b0nhQn cba m9ch ph7i npm trong kho7ng tn3000y8cn 7000y. T$c 80truy4n / nhQn dZli%u c3c 89i l 100 Kbps. Cc l$i vo cba b0nhQn ph7i c 8i%n dung nhvh.n 2500 pF. 0di cba cp n$i giZa my tnh v thict b`ghp n$i qua ckng n$i ticp khng thVv15t

qu 15 m ncu khng sRdXng modem. Cc gi trt$c 80Baud chuqn l: 50, 75, 110, 150, 300, 600, 1200, 2400, 4800, 9600,

19200, 28800, 38400, 56000, 115200

5.1.3 $]u nZi trn my tnh PCH,u hct cc my tnh c nhn hi%n nay 84u 815c trang b`t nh6t l m0t ckng n$i ticp

RS-232. S$l15ng ckng c thVl 2, 3 homc thQm ch ln t-i 4. Khi 8 ng1_i ta quy 1-c 8nhs$thet3cc ckng l COM1, COM2, COM3 v COM4 (ncu c). C hai kiVu 8,u n$i 815c sRdXng cho ckng n$i ticp RS-232 l lo9i 9 chn (DB9) homc 25 chn (DB25). Tuy c cng s$chn v-i ckng song song (cn gNi l ckng my in LPT) l 25 chn, nh1ng ckng n$i ticp 25chn trn my tnh l ckng 83c (male) cn ckng song song l ckng ci (female). Nh_8mc 8iVmny m ta c thVphn bi%t 2 lo9i ckng v-i nhau.

S.8!chn cba ckng n$i ticp 9 chn v 25 chn nh1sau:

Hnh 5.1 S3'7chn c)a cCng n$i ti;p 9 chn


31/68



Hnh 5.2 S3'7chn c)a cCng n$i ti;p 25 chn

D25 D9 Tn hi%u H1-ng truy4n M t71 - - - N$i 86t b7o v%2 3 TxD DTEDCE DZli%u truy4n3 2 RxD DCE DTE DZli%u nhQn4 7 RTS DTEDCE DTE yu c,u truy4n dZli%u5 8 CTS DCE DTE DCE szn sng nhQn dZli%u

6 6 DSR DCE DTE DCE szn sng lm vi%c7 5 GND - N$i 86t8 1 DCD DCE DTE DCE pht hi%n sng mang20 4 DTR DTEDCE DTE szn sng lm vi%c22 9 RI DCE DTE Bo chung23 - DSRD DCE DTE D t$c 80truy4n24 - TSET DTEDCE Tn hi%u 8`nh th_i truy4n 8i tnDTE15 - TSET DCE DTE Tn hi%u 8`nh th_i truy n tnDCE 8

truy4n dZli%u17 - RSET DCE DTE Tn hi%u 8`nh th_i truy n tnDCE 8

nhQn dZli%u

18 - LL Ki m tra c ng21 - RL DCE DTE T9o ra bfi DCE khi tn hi%u nhQn tnDCE ldi

14 - STxD DTEDCE DZli%u truy4n the216 - SRxD DCE DTE DZli%u nhQn the219 - SRTS DTEDCE Yu c,u gfi the213 - SCTS DCE DTE Xa 8Vgfi the212 - SDSRD DCE DTE D t$c 80truy4n the225 - TM Chc80Test9 - Dnh ring cho chc80Test10 - Dnh ring cho chc80Test11 - Khng dng

Bng 5.2 Ch/c n-ng cc chn c)a RS232

5.1.4 Qu trnh truyUn deliNu5.1.4.1 Qu trnh truyUn deliNu

Vi%c truy4n dZ li%u qua ckng n$i ticp RS-232 815c th3c hi%n theo kiVu khng 8!ngb0. V thc, t9i m0t th_i 8iVm chgc m0t bit 815c truy4n. B0truy4n gRi m0t bit brt 8,u (startbit) 8Vthng bo cho b0nhQn bict m0t k t3so815c gRi 8cn trong l,n truy4n bit ticp theo.


32/68



Bit ny lun brt 86u fmec 0. Ticp theo l cc bit dZli%u (data bits) 815c gRi d1-i d9ng mASCII (c thVl 4, 5, 6, 7 homc 8 bit dZli%u). Sau 8 l m0t bit chzn li(parity bit, c thVchomc khng) v cu$i cng l bit dnng (stop bit, c thVl 1, 1.5 homc 2 bit dnng).

5.1.4.2 TZc TdBaudM0t trong cc tham s$8mc tr1ng cho qu trnh truy4n dZ li%u qua ckng n$i ticp RS-

232 l t$c 80truy4n nhQn dZli%u, cn gNi l t$c 80bit. T$c 80bt 815c 8`nh nghsa l s$bttruy4n trong 1 giy. C7b0truy4n v b0nhQn ph7i thict lQp 8Vho9t 80ng cng v-i t$c 80bitny.

Ngoi t$c 80bit cn c m0t thuQt ngZkhc 815c sRdXng 8Vm t7t$c 80truy4n, 8 lt$c 80Baud. T$c 80bit ph7n nh t$c 80th3c tcm cc bit 815c truy4n, cn t$c 80Baud linquan 8cn t$c 80m cc ph,n tRm ha dZli%u 815c sRdXng 8Vdi'n t7cc bit 815c truy4n.Bfi v m0t ph,n tRbo hi%u s3m ha m0t bit, nn khi 8 hai t$c 80l 8!ng nh6t. Chgtrongcc odem, do c thm qu trnh bicn 8ki nn t$c 80bit m-i khc t$c 80Baud.

M0t s$t$c 80Baud th1_ng dng: 50, 75, 110, 150, 300, 600, 1200, 2400, 4800, 9600,19200, 28800, 38400, 56000, 115200

M0t trong nhZng yu c,u quan trNng khi sRdXng chuqn truy4n thng n$i ticp RS-232l th_i gian chuyVn mec logic khng 815c v15t qu 4% th_i gian truy4n 1 bit. V thc, ncu t$c

80bit cng cao, th_i gian truy4n 1 bit cng nhv, th th_i gian chuyVn mec logic ph7i cng nhv.V6n 84ny lm gi-i h9n t$c 80Baud v kho7ng cch truy4n. V dX, v-i t$c 80Baud l 19200,ta c thVtruy4n xa nh6t l 50 feet (kho7ng 15,24 m).

5.1.4.3 Bit chqn lh(parity bit)Th3c ch6t cba qu trnh kiVm tra ldi khi truy4n dZ li%u l bksung thm dZ li%u vo

dng dZli%u 815c truy4n 8Vtm ra homc sRa chZa m0t ldi trong qu trnh truy4n. Chuqn RS-232 sRdXng m0t kOthuQt 8.n gi7n 815c gNi l kiVm tra chzn li(parity checking).

M0t bit chzn li(parity bit) 815c bksung vo dZli%u 815c truy4n 8Vcho th6y s$l15ngcc bit 1 815c gRi trong m0t khung truy4n l chzn (parity chzn) homc li(parity li). y lm0t ph1.ng php 8.n gi7n 8Vm ha ldi v chgc,n m0t ckng XOR 8Vt9o ra parity bit. Parity

bit 815c bksung vo dZli%u 815c truy4n bpng cch chn n vo m0t v`tr chnh xc cba bit

trong thanh ghi d`ch.sau khi 8 8cm xem c bao nhiu bit 1 815c gRi. M0t parity bit chgcthVtm ra m0t s$licc ldi, chung h9n nh11, 3, 5, 7, Ncu nh1c m0t s$chzn cc bit mrcldi th parity bit sotrng gi trv-i tr1_ng h5p khng mrc ldi v khng thVpht hi%n ra ldi. Vthc, kOthuQt m ha ldi ny th1_ng khng 815c sRdXng trong tr1_ng h5p c kh7n)ng m0tvi bit b`mrc ldi.

5.1.5 Brt tay (Hand shaking)Vi%c truy4n dZli%u c thVticn hnh theo 3 cch: khng c brt tay, brt tay bpng ph,n

ceng v brt tay bpng ph,n m4m.

5.1.5.1 TruyUn deliNu khng brt tayTrong cch truy4n dZli%u ny, ng1_i ta gi7thict rpng b0nhQn (receiver) c thV8Nc dZli%u tnb08%m nhQn (receive buffer) tr1-c khi k t3khc 815c nhQn v4. DZli%u 815c gRi tn

v`tr kct n$i v-i chn TxD cba b0truy4n (transmitter) v 815c nhQn fv`tr n$i v-i chn RxDcba b0nhQn. Khi DTE (chung h9n nh1m0t my tnh) n$i v-i DTE khc th TxD cba thict b`ny son$i v-i v-i RxD cba thict b` kia v ng15c l9i. !ng th_i cc chn DTR v DSR 815cn$i nhau, RTS v CTS 815c n$i nhau trn cng m0t thict b`.


33/68



Hnh 5.2 S3'7n$i chn gi@a DTE v DCE

5.1.5.2 Brt tay bsng ph]n cXngBrt tay ph,n ceng lm dnng cc k t3trong b08%m nhQn 8Vkhvi b`ghi 8 ln. Cc

81_ng d2n 815c sRdXng 84u 815c kch ho9t fmec cao. Khi b0truy4n mu$n truy4n dZli%u,n cho 81_ng d2n RTS ftr9ng thi ho9t 80ng, r!i gim st 81_ng d2n CTS cho t-i khi 81_ngd2n ny chuyVn sang tr9ng thi ho9t 80ng. Ncu CTS v2n cn 8ang ftr9ng thi ch1a ho9t 80ngnghsa l b0nhQn 8ang bQn, khng thVnhQn dZli%u. Khi b0nhQn 8Nc tnb08%m nhQn xong,81_ng d2n RTS sot380ng chuyVn sang tr9ng thi kch ho9t 80ng 8Vbo cho b0truy4n l n

8 szn sng nhQn dZli%u. Vi%c nhQn dZli%u clng di'n ra t1.ng t3v-i vi%c truy4n dZli%u, khi8 cc 81_ng d2n DSR v DTR 815c sRdXng.

5.2 Chunn RS-232 v RS-485RS-232 v RS-485 l 2 chuqn truy4n thng n$i ticp thng dXng nh6t. Trong khi RS-

232 815c sRdXng r6t r0ng ri v 815c tch h5p trong mNi my tnh c nhn th chuqn RS-485815c ra 8_i 8Vp dXng trong cng nghi%p, n.i t!n t9i nhZng yu c,u m RS-232 khng 8peng 815c. Gi-i h9n cba chuqn RS-232 l ft$c 80truy4n th6p, kho7ng cch truy4n ngrn, kh7n)ng ch$ng nhi'u km v chgc thVgiao ticp 2 thict b`v-i nhau. Trong khi 8 chuqn RS-485c thV8p eng 815c t6t c7cc yu c,u ny:

T$c 80truy4n cao t-i h.n 100 kbps fkho7ng cch 1200m. Giao ticp 815c nhi4u DTE v-i nhau cng trn m0t 81_ng truy4n. Kh7n)ng tri%t nhi'u cao.

Chuqn RS-232 sRdXng 3 chn Pht, Thu v 6t chung v quy 8`nh mec logic theochuqn 8i%n p TTL. V mec logic 815c xc 8`nh bpng 8i%n p chnh l%ch tuy%t 8$i so v-i 86tnn r6t d'b`nhi'u can thi%p. Cn chuqn RS-485 sRdXng 2 chn truy4n tn hi%u cho knh phthomc thu v mec logic 815c xc 8`nh bfi 8i%n p chnh l%ch t1.ng 8$i giZa 2 chn ny. i%np chnh l%ch ny ln t-i vi chXc volt v 2 81_ng dy truy4n ring bi%t nn khi xu6t hi%nnhi'u chng cng 1 tc 80ng nh1nhau nn RS-485 tri%t nhi'u c3c kxt$t. V mdi knh truy4nc 2 81_ng dy nn c thVxorn 2 81_ng dy ny l9i 8Vt)ng kh7n)ng ch$ng nhi'u.


34/68



Hnh 5.3 -Dnh h0=ng c)a tFnhiGu ln dy truy


35/68


GVHD: ThS. Nguy'n V)n Nga Ch1.ng 4 : Cc h%th$ng RFID

Trong ph,n ny, chng ta so tm hiVu cc h% th$ng RFID c.b7n, cch thec ho9t80ng clng nh1m$i lin h%giZa transponder v reader. Chng ta quan tm 8cn 2 v6n84 chnh: n)ng l15ng cung c6p cho transponder v ph1.ng thec truy4n dZ li%u giZatransponder v reader. Trong th3c tch%th$ng RFID c thVchia lm 3 lo9i c.b7n 8l: h%th$ng 1 bit, h%th$ng song cng v bn song cng v h%th$ng tu,n t3.

- H%th$ng 1 bit.- H%th$ng n bit:+ H%th$ng song cng v bn song cng.+ H%th$ng tu,n t3.

Hnh 4.1 Cc h+th$ng RFID khc nhau

4.1 HNthZng 1 bitM0t bit l 89i l15ng nhvnh6t cba thng tin, n c 2 tr9ng thi: 1 hay 0. i4u

ny c nghsa l chgc 2 tr9ng thi 815c trnh by bfi transponder 1 bit: transpondertrong vng thqm v6n v khng c transponder trong vng thqm v6n. Mmc d b`gi-ih9n, cc transponder 1 bit v2n r6t phkbicn, eng dXng chnh cba chng l cc thict b`ch$ng tr0m trong cc cRa hng (EAS, gim st hng ho 8i%n tR).

M0t h%th$ng EAS 815c lm bfi cc linh ki%n sau: anten cba reader hay b0dhvi, ph,n tRb7o mQt hay thib7o mQt v m0t thict b`v hi%u ho h%th$ng sau khi kct

thc giao d`ch. Trong cc h%th$ng hi%n 89i, vi%c v hi%u ho 815c th3c hi%n khi mcba mn hng 815c 8)ng k t9i qu,y tnh ti4n. M0t vi h%th$ng clng 8mt thm b0kchho9t 8Vkch ho9t l9i ph,n tRb7o mQt sau khi v hi%u ho h%th$ng. M0t 8mc 8iVm quantrNng cba h%th$ng l t$c 80pht hi%n phXthu0c vo 80r0ng cba ckng (kho7ng cchl-n nh6t giZa transponder v anten cba reader).

Transponder 1 bit g!m 5 thnh ph,n:- T,n s$v tuycn- Sng vi ba


36/68


37/68



Cc anten khung di%n tch l-n dng 8Vpht ra tr1_ng tnc,n thict trong vngtruy v6n. Anten khung 815c tch h5p vo c0t v 815c n$i v-i ckng. Ncu ckng c b4r0ng d1-i 2m th ta c thVsRdXng h%th$ng RFID t,n s$v tuycn.

Hnh 4.3 Anten khung c)a h+th$ng RF (cao 1.2 1.6 m) v transponder

H%s$phqm ch6t Q cba ph,n tRb7o mQt >60 80C1_ng 80tr1_ng v hi%u ha c3c tiVu HD 1.5 (A/m)

C1_ng 80tr1_ng c3c 89i trong t,m v hi%u ha 0.9 (A/m)Bng 4.1Cc tham s$h+th$ng cho cc h+th$ng RF

H%th$ng 1 H%th$ng 2 H%th$ng 3 H%th$ng 4T,n s$(MHz) 1.86 2.18 7.44 8.73 7.30 8.70 7.40 8.60T,n s$ qut(Hz)

141 141 85 85

Bng 4.2 Di t"n s$c)a cc h+th$ng bo mBt khc nhau

4.1.2 Sng vibaCc h%th$ng EAS trong d7i viba sRdXng vi%c t9o ra cc hi bpng cc linh ki%n

c 8mc tuycn phi tuycn (v dX: diode). Hi cba m0t 8i%n p hnh sin A c t,n s$fAlm0t 8i%n p hnh sin B v-i t,n s$fBl s$nguyn l,n t,n s$fA. Cc hi bQc cao cba t,ns$fAl 2fA, 3fA, 4fA.

M9ch cba transponder 1 bit 8Vt9o ra cc hi r6t 8.n gi7n: m0t diode 8i%n dung815c n$i v-i m0t anten dipole 815c chgnh f t,n s$ sng mang (Hnh 4.4). Antendipole t,n s$ 2,45GHz c chi4u di tkng c0ng l 6cm. Cc t,n s$ sng mang 815cdng l 915MHz, 2,45GHz, 5,6GHz. Ncu transponder npm trong t,m cba anten pht,dng 8i%n trong diode sot9o ra hi cba sng mang, 8mc bi%t l cc hi bQc 2 hay bQc 3,tuxthu0c vo lo9i diode 815c chNn.


38/68



Hnh 4.4 M&ch c3bn v hnh d&ng c2th4c)a transponder vibaHnh 4.5 biVu di'n transponder 815c 8mt trong t,m cba anten pht ho9t 80ng f

t,n s$2,45GHz. Hi bQc 2 cba sng mang c t,n s$4,9GHz 815c pht l9i v 815c tchbfi b0thu. S3xu6t hi%n hi bQc 2 cba tn hi%u c thVkch ho9t h%th$ng bo 80ng.

Hnh 4.5 Transponder viba nIm trong vng truy v6n c)a detector

Ncu sng mang 815c 8i4u chcASK hay FSK th t6t c7cc hi clng soc cng

m0t d9ng 8i4u chcnh1vQy. i4u ny gip cho h%th$ng phn bi%t tn hi%u nhi'u v tnhi%u c ch, ng)n chmn bo 80ng sai do cc tn hi%u bn ngoi tc 80ng vo.tv dX trn, sng mang 815c 8i4u chcASK v-i tn hi%u 1kHz tn hi%u nhQn

815c fb0thu 815c gi7i 8i4u chcr!i 81a 8cn b0tch sng 1kHz. Tn hi%u nhi'u xu6thi%n ft,n s$4,9GHz khng thVkch ho9t bo 80ng sai v chng th1_ng khng 815c8i4u chcv ncu c th chng soc m0t cch 8i4u chckhc.

4.1.3 Bdchia t]n sZH%th$ng ny ho9t 80ng v-i b1-c sng di tn100 -135,5kHz. Transponder g!m

c m0t vi m9ch v m0t cu0n dy c0ng h1fng bpng 8!ng trng men. M9ch c0ng h1fng815c hn v-i tX8Vc0ng h1fng t9i t,n s$ho9t 80ng cba h%th$ng. NhZng transponder

ny c thVlm bpng plastic v c thVl6y 8i khi hng ha 815c mua.

Hnh 4.6 S3'7m&ch 'i+n v ho&t '(ng c)a EAS sJd2ng b(chia t"n s$

Vi m9ch trong transponder nhQn n)ng l15ng tn tr1_ng tncba thict b`an ninh(Security device). T,n s$fcu0n t3c7m 815c chia 2 bpng vi m9ch v 815c gRi ng15ctrfl9i thict b`an ninh. Tn hi%u ny h!i ticp v4bpng m0t dy ronhnh 8cn cu0n dy.

T,n s$ 130 KHzKiVu 8i4u chc 100% ASKT,n s$8i4u chc/tn hi%u 8i4u chc 12.5 Hz hay 25 Hz

Bng 4.3 Cc thng s$c3bn c)a h+th$ng


39/68



Tr1_ng tncba transponder xung fm0t t,n s$th6p (8i4u chcASK) 8Vc7i thi%nt$c 80nhQn d9ng. T1.ng t3 nh1nhQn d9ng bpng cc hi, vi%c 8i4u chc sng mang(ASK hay FSK) 815c duy tr fphn nRa t,n s$ pht (subharmics). N 815c dng 8Vphn bi%t giZa nhi'u v tn hi%u c ch. Anten khung 815c dng lm anten c7m bicn.

4.1.4 Transponder trPpng TiNn tlTransponder tr1_ng 8i%n tnsRdXng tntr1_ng m9ch trong kho7ng NF tn10Hz8cn 20Hz. Transponder chea m0t d7i kim lo9i tntnh d'bicn d9ng d1-i tc 80ng cbango9i l3c. S3 tnho cba nhZng d7i kim lo9i ny th1_ng 815c lmp l9i theo chu kxvchng sob`b7o ho cba tr1_ng tnnh_vo m0t tntr1_ng m9nh. M$i quan h%khngtuycn tnh cba c1_ng 80tr1_ng H v thng l15ng c7m eng tnB g,n b7o ho c0ng v-is3thay 8ki cba c7m eng tnB fln cQn cba 8iVm zero cba c1_ng 80tr1_ng tnH, phtsinh ra cc hi f t,n s$c.b7n cba transponder. NhZng hi ny c thV815c nhQn v815c 1-c lu5ng bfi transponder.

Transponder tr1_ng 8i%n tn815c t$i 1u ho bpng cch thn vo nhZng thnhph,n tn hi%u c t,n s$cao h.n tn hi%u chnh. Ngoi nhZng hi cba t,n s$chnh, cn

c thm cc t,n s$tkng hay hi%u cba cc tn hi%u 8 cung c6p. Gi7sRtn hi%u chnh ct,n s$ fS= 20Hz v cc tn hi%u thm vo f1= 3,5kHz v f2= 5,3kHz th nhZng tnhi%u sau 8y 815c pht ra:

f1+ f2= f1+2 = 8,8kHz (4.1)f1 f2= f1-2 = 1,8kHz (4.2)fS+ f1= fS-1 = 3,52kHz (4.3)

Transponder khng ph7n eng l9i v-i hi cba t,n s$c.b7n nh1ng l9i b`tc 80ngbfi t,n s$tkng hay hi%u cba cc tn hi%u thm vo. Cc transponder ny fd9ng cc d7ib)ng dnh c chi4u di kho7ng cch tn vi cm 8cn 20cm. Do t,n s$ ho9t 80ng c3cth6p, cc h%th$ng tr1_ng 8i%n tnchgthch h5p v-i nhZng s7n phqm c chea kim lo9i.Tuy nhin, nhZng h% th$ng ny c khuyct 8iVm l ho9t 80ng cba transponder phX

thu0c vo v` tr: 8Vqu trnh nhQn d9ng l tin cQy th tr1_ng tncba transponder ph7inpm dNc xuyn qua cc d7i kim lo9i.

Hnh 4.7 Anten c)a h+th$ng RFID 'i+n tF(cao 1.40 m) v transponderVv hi%u ho, transponder 815c khoc ln hay phbm0t ph,n bpng nhZng t6m

kim lo9i tnceng. tqu,y thu ngn, ng1_i nhn vin ch9y m0t nam chm vsnh cRu dNctheo t6m kim lo9i 8Vv hi%u ho transponder. Vi%c lm ny sotnho nhZng t6m kimlo9i che phb. Cc d7i kim lo9i 815c thict kcsao cho 80tnd1cba nhZng t6m kim lo9i


40/68



thuQn ti%n cho nhZng d7i kim lo9i d'bicn d9ng ny f8iVm b7o ho nhpm lm chotr1_ng tncba h%th$ng an ninh khng thVb`kch ho9t 815c nZa.

Transponder c thVkch ho9t trfl9i fb6t ceth_i 8iVm no bpng qu trnh ti tnho. Qu trnh ny c thVth3c hi%n v-i s$l,n khng h9n chc. Do nhZng transpondernhvv riti4n, nhZng h%th$ng ny by gi_815c sRdXng ngy cng nhi4u trong cng

nghi%p.V89t 815c 80m9nh tr1_ng c,n thict cho qu trnh ti tnho cc d7i kim lo9i,tr1_ng 815c pht ra bpng h%th$ng 2 cu0n dy trn cc c0t fl$i 8i. Vi cu0n dy ring,th1_ng l tn9 8cn 12, npm trn 2 c0t v chng pht ra tr1_ng tnycu ftrung tm vm9nh h.n 8$i v-i tr1_ng tnfbn ngoi. 0r0ng cba ckng ln 8cn 1,5m c thV th3chi%n bpng cch ny trong khi t$c 80nhQn d9ng 89t 815c bpng 70%.4.2 HNthZng song cng v bn song cng

Tri v-i cc transponder 1 bit th1_ng khai thc nhZng hi%u eng vQt l 8.n gi7ncho qu trnh nhQn d9ng, cc transponder d1-i 8y sRdXng m0t vi m9ch lm thict b`mang dZli%u. N c m0t vng l1u trZdZli%u ln t-i vi kByte. V8Nc hay ghi dZli%uvo thict b`mang dZli%u ny th ph7i th3c hi%n vi%c truy4n dZli%u giZa transponder

v reader. Vi%c truy4n dZli%u ny c thVl song cng homc bn song cng hay tu,n t3.- Trong truy4n bn song cng: dZli%u tntransponder 8cn reader 815c truy4n xenkov-i dZ li%u tn reader 8cn transponder. t t,n s$d1-i 30MHz, h% th$ng th1_ng sRdXng ph1.ng php load modulator c hay khng c sng mang phX8V8i4u chc dZli%u.

- Trong truy4n song cng: dZ li%u tn transponder v reader c thV truy4n cngm0t lc.

Tuy nhin, c72 ph1.ng php 84u ph7i truy4n n)ng l15ng lin tXc tnreader 8cntransponder v 80c lQp v-i h1-ng truy4n lu!ng dZli%u. Tri l9i trong cc h%th$ng tu,nt3(SEQ: Sequential system), vi%c truy4n n)ng l15ng tn transponder 8cn reader 815cgi-i h9n trong m0t chu kx th_i gian. DZ li%u truy4n tn transponder 8cn reader xu6t

hi%n trong nhZng kho7ng dnng cba n)ng l15ng cung c6p cho transponder.

Hnh 4.8 Truy


41/68



M0t transponder ghp c7m eng bao g!m m0t thict b`mang dZli%u, th1_ng lm0t vi m9ch v m0t cu0n c7m 8ng vai tr cba m0t anten.

Cc transponder ghp c7m eng h,u nh184u ho9t 80ng thX80ng c nghsa l t6tc7cc n)ng l15ng c,n thict cho ho9t 80ng cba vi m9ch 815c cung c6p tn reader. VvQy m cu0n dy anten cba reader pht ra m0t 8i%n tr1_ng cao t,n v m9nh 8VlNt vo

mmt crt v di%n tch xung quanh cu0n dy transponder. Do b1-c sng cba t,n s$ sRdXng (ng pht ra c)areader

M0t ph,n nhvn)ng l15ng ny lNt vo anten cba transponder sinh ra m0t 8i%nthcc7m eng Ui. i%n thcny 815c chgnh l1u v sRdXng nh1l ngu!n cung c6p cho vim9ch. TX Cr cng v-i cu0n c7m cba anten pht t9o thnh m9ch c0ng h1fng, quyct8`nh t,n s$ho9t 80ng cba reader.

Cu0n dy anten v tXC1cba transponder clng t9o thnh m0t m9ch c0ng h1fngt1.ng eng v-i t,n s$pht ra cba reader. i%n thcU cba transponder 89t c3c 89i nh_vo s3gia t)ng c0ng h1fng cba m9ch c0ng h1fng. Hai cu0n dy c thV815c xem nh1

l nh1l m0t bicn p m trong tr1_ng h5p m chgc m0t lin kct r6t ycu giZa chng.v TruyUn deliNu tltransponder T[n reader

Load moudulation: cc h%th$ng ghp c7m eng 84u d3a trn m0t lo9i ghp bicnp (Transformer-type coupling) giZa cu0n s.c6p trong reader v cu0n thec6p trongtransponder npm trong tr1_ng g,n cba anten pht.

Ncu m0t transponder c0ng h1fng (chung h9n nh1m0t transponder c m0t m9chc0ng h1fng eng v-i t,n s$ truy4n 8i cba reader) npm trong tr1_ng tncba reader thtransponder so l6y n)ng l15ng tn thng tn8. Kct qu7h!i ticp cba transponder trnanten cba reader c thVt15ng tr1ng cho trfkhng ZTcba bicn p trong cu0n dy cbareader. ng mfm0t 8i%n trf t7i t9i anten cba transponder sogy ra s3 thay 8ki trfkhng cba ZTv nh1vQy solm thay 8ki 8i%n p fanten cba reader. i4u ny c tc

dXng nh1l 8i4u chcbin 80cba 8i%n p ULcba anten reader bfi m0t transponder fxa.

Ncu vi%c 8ng fkho 815c 8i4u khiVn bfi lu!ng dZli%u th dZli%u ny c thV815c truy4n 8i tn transponder 8cn reader. Lo9i truy4n dZ li%u nh1vQy c thV gNi lLoad modulation.

V khi phXc dZ li%u cba reader, 8i%n p f anten cba reader 815c chgnhl1u.Vi%c ny gi$ng nh1gi7i 8i4u chcm0t tn hi%u 8i4u bin.


42/68



Hnh 4.10 Truy


43/68



Ph1.ng php hi phX(Subharmonic): hi phXcba m0t tn hi%u hnh sin bin 80A c t,n s$ l fA l m0t tn hi%u hnh sin c bin 80B, t,n s$fBbpng v-i m0t trongnhZng gi trsau : fA/2, fA/3, fA/4.

Trong nhZng ph1.ng php hi phX, t,n s$fBc 815c bpng cch l6y t,n s$fAdoreader pht 8i chia cho 2. Tn hi%u ng ra fBcba m0t b0chia nh`phn 815c 8i4u chc

v-i lu!ng dZ li%u tntransponder. Tn hi%u 8 8i4u chcsau 8 815c h!i ticp v4antencba transponder thng qua m0t b0li. Th1_ng ng1_i ta sRdXng t,n s$fA= 128kHz vt,n s$fB= 64kHz.

Hnh 4.12 S3'7m&ch c)a transponder hi ph2Anten cba transponder g!m c m0t cu0n dy v-i m0t van trung tm. y clng

l n.i n)ng l15ng 815c cung c6p l6y tn8iVm cu$i. Tn hi%u quay v4cba transponder815c h!i ticp vo cu0n the2.

4.2.2 Ghp TiNn tltn x_liv Cung cjp nIng lP^ng cho transponderCc h% th$ng RFID c kho7ng cch giZa reader v transponder l-n h.n 1 m

815c gNi l h%th$ng c kho7ng cch di (long range). NhZng h%th$ng ny ho9t 80ngf t,n s$ 868MHz (Europe) v 915MHz (USA), f t,n s$ vi ba 2,5GHz v 5,8GHz.B1-c sng ngrn cba nhZng d7i t,n ny ph h5p v-i c6u trc cba anten c kch th1-cnhvv hi%u su6t cao h.n khi sRdXng ft,n s$d1-i 30MHz.

V c thV truy xu6t n)ng l15ng c szn cho ho9t 80ng cba m0t transponderchng ta ph7i tnh suy hao 81_ng truy4n trong khng gian t3do F:

!F= - 146.7 + 20 log(r) + 20log(f) 10log(GT) 10log(GR) (4.4)Trong 8:

r : kho7ng cch tnreader 8cn transponder.

GT,GR: 80l5i cba anten transponder v reader.f : t,n s$pht cba reader.

Kho7ng cch r 868 MHz 915 MHz 2.45 HGz0.3 m 18.6 dB 19.0 dB 274.6 dB1 m 29.0 dB 29.5 dB 38.0 dB3 m 38.6 dB 39.0 dB 47.6 dB10m 49.0 dB 49.5 dB 58.0 dB


44/68



Bng 4.4Suy hao '0>ng truy


45/68



H%th$ng ghp g,n 815c thict kccho kho7ng cch tn0,1cm 8cn t$i 8a l 1cm.transponder 815c chn vo trong reader homc 8mt vo trong b4mmt 8nh d6u 8Vho9t80ng.

Hnh 4.14 Transponder ghp g"n '0Kc '0a vo trong reader1a transponder vo trong reader sao cho cu0n c7m cba n npm 8ng v` tr

trong khe khng kh. Reader l cu0n s.c6p v transponder l cu0n thec6p t9o thnhm0t bicn p. M0t dng 8i%n cao t,n bicn thin trong cu0n s.c6p pht ra m0t tr1_ng tncao t,n trong li, khe khng kh cu0n c7m cba transponder. Tn hi%u ny 815c chgnhl1u r!i dng 8Vcung c6p n)ng l15ng cho chip.

Do 8i%n p c7m eng U trong cu0n c7m cba transponder tg l%v-i t,n s$ f cbadng 8i%n kch thch nn t,n s$815c chNn 8V truy4n n)ng l15ng cng cao cng t$t.Trong th3c tc, t,n s$trong kho7ng tn1-10MHz th1_ng 815c sRdXng. VgiZcho suyhao trong bicn p th6p th li ferrite ph7i ph h5p v-i t,n s$815c chNn.

Khc v-i h% th$ng ghp c7m eng hay viba, hi%u su6t truy4n tn reader 8cntransponder r6t cao. Do 8 h%th$ng ghp g,n l m0t l3a chNn r6t t$t cho nhZng chiptiu thXn)ng l15ng nhi4u. Chnh v l do ny m nhZng thighp g,n 84u c chea vi

xRl.v TruyUn deliNu tltransponder T[n reader

Ghp tn: load modulation v-i sng mang phXclng 815c dng 8Vtruy4n dZli%utrong ghp tntntransponder 8cn reader trong h%th$ng ghp g,n. T,n s$sng mangphXv qu trnh 8i4u chc815c qui 8`nh trong ISO 10536.4.2.4 Ghp TiNnv Cung cjp nIng lP^ng cho transponder thVTdng

V-i cc h%th$ng ghp 8i%n, reader pht ra m0t tr1_ng 8i%n cao t,n kh m9nh.Anten cba reader c m0t b7n kim lo9i di%n tch l-n v d2n 8i%n (8i%n c3c). Ncu m0t8i%n thccao t,n 815c 8mt vo 8i%n c3c, m0t 8i%n tr1_ng cao t,n 815c hnh thnh giZa8i%n c3c v 8iVm 86t. i%n thcny trong kho7ng vi tr)m 8cn vi ngn volt 815c phtra tnreader bpng cch t)ng 8i%n thctrong m9ch c0ng h1fng lm tncu0n L1mrc songsong v-i tXC1v tXkch ho9t CR-GND giZa 8i%n c3c v 86t. T,n s$c0ng h1fng cbam9ch c0ng h1fng bpng v-i t,n s$truy4n cba reader.

Anten cba transponder l 2 dy d2n npm trn 8i%n c3c. Ncu transponder npmtrong 8i%n tr1_ng cba reader th m0t 8i%n thcsosinh ra giZa 2 c3c cba n. i%n thcny 815c dng 8Vcung c6p cho chip cba transponder.


46/68



Hnh 4.15 H+th$ng ghp 'i+n sJd2ng 'i+n tr0>ng '4truy


47/68



4.3 HNthZng tu]n tbNcu truy4n dZli%u v n)ng l15ng tnreader 8cn thict b`mang dZli%u r!i sau 8

dZ li%u so 815c truy4n ng15c tn transponder 8cn reader th chng ta gNi 8y l h%th$ng tu,n t3SEQ.4.3.1 Ghp cMm Xngv Cung cjp nIng lP^ng cho transponderCc h%th$ng tu,n t3sRdXng lin kct tnho9t 80ng ring ft,n s$d1-i 135kHz.

M0t my bicn thclo9i lin kct 815c t9o ra giZa cu0n dy cba reader v cu0n dy cbatransponder. i%n p c7m eng pht ra trong cu0n c7m cba transponder do tc 80ng cbatr1_ng bicn thin tnreader 815c chgnh l1u v sRdXng trong m9ch.

Vnng cao hi%u su6t truy4n dZ li%u, t,n s$ho9t 80ng cba transponder ph7ichnh xc v-i reader v ch6t l15ng cba cu0n c7m cba transponder ph7i thQt ph h5p.V l do ny m transponder c m0t tX8i%n trn chip 8Vb cho dung sai cba m9chc0ng h1fng.

Tuy nhin, khng gi$ng nh1h%th$ng song cng v bn song cng, fh%th$ngtu,n t3, b0pht cba reader khng ho9t 80ng m0t cch lin tXc. N)ng l15ng truy4n 8cn

my pht trong su$t qu trnh n9p cho tX8Vcung c6p m0t n)ng l15ng l1u trZ. Chipcba transponder 815c chuyVn sang chc80ho9t 80ng tict ki%m n)ng l15ng trong su$tqu trnh ho9t 80ng. H,u nh1n)ng l15ng nhQn 815c 84u sRdXng 8Vn9p cho tXn9p.Sau m0t chu kxc$ 8`nh, my pht cba reader 815c trt.

N)ng l15ng tch trZ trong transponder 815c dng 8VgRi m0t thng 8i%p 8p l9icho reader. i%n dung nhvnh6t cba tXn9p c thV815c tnh tncng thec:

$ =%&=

'.(

[)*+,-./01] (4.5)

Trong 8 :Vmin, Vmax : l nhZng gi trgi-i h9n cho 8i%n p ho9t 80ng khng qu

mec cho php.I: l dng tiu thXcba chip trong su$t th_i gian ho9t 80ng.t: th_i gian c,n thict 8Vtruy4n dZli%u tntransponder 8cn reader.

v TruyUn deliNu tltransponder T[n readerTrong cc h%th$ng tu,n t3, m0t chu kx8Nc g!m c 2 pha, pha n9p v pha 8Nc.

Hnh 4.17 S3'7kh$i c)a transponder tu"n t9sJd2ng ghp cm /ng


48/68



Hnh 4.18 S3'7'i+n p c)a t2n&p

Cu$i pha n9p 815c tch bfi m0t b0end of burts detector. B0ny gim st s3thay 8ki 8i%n p trn cu0n c7m cba transponder, tn8 nhQn bict ngay khi tntr1_ng cbareader b`trt. tcu$i pha n9p, m0t b0dao 80ng on chip 815c kch ho9t. B0dao 80ngny sRdXng m9ch c0ng h1fng nh_vo cu0n c7m cba transponder nh1l thnh ph,n

nhQn d9ng t,n s$. Cu0n c7m cba transponder pht ra m0t tr1_ng tnycu. Reader c thVnhQn 815c tr1_ng tnny. Tr1_ng ny c7i thi%n tgs$S/N t)ng ln m0t l15ng kho7ng 20dB so v-i h%th$ng song cng/ bn song cng.

T,n s$ truy4n cba transponder bpng v-i t,n s$c0ng h1fng cba cu0n c7m cbatransponder. T,n s$ny 815c hi%u chgnh l9i cho gi$ng v-i t,n s$truy4n 8i cba readerkhi n 815c pht.

Vc thV8i4u chctn hi%u HF pht ra trong khi khng c n)ng l15ng cung c6p,m0t tXc 8i%n 815c mrc song song v-i m9ch c0ng h1fng 8ng lc v-i lu!ng dZ li%u.Kct qu7l t9o ra 815c 2 tn hi%u FSK.

Sau khi ton b0dZ li%u 815c pht, chc80x7815c kch ho9t 8Vx7ton b0 tXn9p. i4u 8 87m b7o an ton cho qu trnh reset ngu!n f8,u chu kxn9p kcticp.


49/68


GVHD : ThS. Nguy'n V)n Nga Ch1.ng 6 : C.sfl thuyct v4xRl 7nh

6.1 GiQi thiNu6.1.1 X\l Mnh l g?

Con ng1_i thu nhQn thng tin qua cc gic quan, trong 8 th`gic 8ng vai tr quantrNng nh6t. NhZng n)m trfl9i 8y v-i s3pht triVn cba ph,n ceng my tnh, xRl 7nh v 8!ho98 pht triVn m0t cch m9nh mov c nhi4u eng dXng trong cu0c s$ng. XRl 7nh v 8!ho98ng m0t vai tr quan trNng trong t1.ng tc ng1_i my. Qu trnh xR l 7nh 815c xemnh1l qu trnh thao tc 7nh 8,u vo nhpm cho ra kct qu7mong mu$n. Kct qu78,u ra cbam0t qu trnh xRl 7nh c thVl m0t 7nh t$t h.n homc m0t kct luQn.

Hnh 6.1

Qu trnh xJl nh

?nh c thVxem l tQp h5p cc 8iVm 7nh v mdi 8iVm 7nh 815c xem nh1l 8mc tr1ngc1_ng 80sng hay m0t d6u hi%u no 8 t9i m0t v`tr no 8 cba 8$i t15ng trong khng gianv n c thVxem nh1m0t hm n bicn P(c1, c2,..., cn). Do 8, 7nh trong xRl 7nh c thVxemnh17nh n chi4u.S.8!tkng qut cba m0t h%th$ng xRl 7nh:

Hnh 6.2 Cc b0Hc c3bn trong m(t h+th$ng xJl nh

6.1.2 Cc vjn TUcRbMn trong x\l Mnh6.1.2.1 Mdt sZkhi niNm cRbMn*Dnh v 'i4m nh:

iVm 7nh 815c xem nh1 l d6u hi%u hay c1_ng 80 sng t9i 1 to9 80 trongkhng gian cba 8$i t15ng v 7nh 815c xem nh1l 1 tQp h5p cc 8iVm 7nh.

* M/c xm, muL s$cc gi trc thVc cba cc 8iVm 7nh cba 7nh.

6.1.2.2 Chinh mXc xmNhpm khrc phXc tnh khng 8!ng 84u cba h%th$ng gy ra. Thng th1_ng c 2 h1-ng

ticp cQn: Gi7m s$ mec xm: Th3c hi%n bpng cch nhm cc mec xm g,n nhau thnh m0t b.Tr1_ng h5p chgc 2 mec xm th chnh l chuyVn v47nh 8en trrng. Wng dXng: In 7nh mu ramy in 8en trrng.


50/68



T)ng s$mec xm: Th3c hi%n n0i suy ra cc mec xm trung gian bpng kOthuQt n0isuy. KOthuQt ny nhpm t)ng c1_ng 80m`n cho 7nh.

6.1.2.3 Trch chKn Toc TiYm

Cc 8mc 8iVm cba 8$i t15ng 815c trch chNn tuxtheo mXc 8ch nhQn d9ng trong qutrnh xRl 7nh. C thVnu ra m0t s$8mc 8iVm cba 7nh sau 8y:$oc TiYm khng gian: Phn b$mec xm, phn b$xc su6t, bin 80, 8iVm u$n v.v..$oc TiYm bi[n Tgi: Cc 8mc 8iVm lo9i ny 815c trch chNn bpng vi%cth3c hi%n lNc vng(zonal filtering). Cc b0vng 815c gNi l mmt n98mc 10 8iVm (feature mask) th1_ng l cckhe hjp v-i hnh d9ng khc nhau (chZnhQt, tam gic, cung trn v.v..)$oc TiYm bin v TPpng bin: mc tr1ng cho 81_ng bin cba 8$i t15ng v do vQy r6t hZuch trong vi%c trch trNn cc thu0c tnh b6t bicn 815c dng khi nhQn d9ng 8$i t15ng. Cc 8mc8iVm ny c thV815c trch chNn nh_ton tRgradient, ton tRla bn, ton tRLaplace, ton tRcho khng (zero crossing) v.v..Vi%c trch chNn hi%u qu7cc 8mc 8iVm gip cho vi%c nhQn d9ng cc 8$i t15ng 7nh chnh xc,v-i t$c 80tnh ton cao v dung l15ng nh-l1u trZgi7m xu$ng.

6.1.2.4 Nhkn d_ngNhQn d9ng t380ng (automatic recognition), m t78$i t15ng, phn lo9i v phn nhm

cc m2u l nhZng v6n 84quan trNng trong th`gic my, 815c eng dXng trong nhi4u ngnhkhoa hNc khc nhau. Tuy nhin, m0t cu hvi 8mt ra l: m2u (pattern) l g? Watanabe, m0ttrong nhZng ng1_i 8i 8,u trong lsnh v3c ny 8 8`nh nghsa: Ng15c l9i v-i hdn lo9n (chaos),m2u l m0t th3c thV(entity), 815c xc 8`nh m0t cch ang ng (vaguely defined) v c thVgncho n m0t tn gNi no 8. V dXm2u c thV l 7nh cba vn tay, 7nh cba m0t vQt no 8815c chXp, m0t chZvict, khun mmt ng1_i homc m0t k 8! tn hi%u ticng ni. Khi bict m0tm2u no 8, 8VnhQn d9ng homc phn lo9i m2u 8 c thV:Homc phn lo_i c mSu (supervised classification), chung h9n phn tch phn bi%t(discriminant analyis), trong 8 m2u 8,u vo 815c 8`nh danh nh1m0t thnh ph,n cba m0t l-p

8 xc 8`nh.Homc phn lo_i khng c mSu (unsupervised classification hay clustering) trong 8 cc m2u815c gn vo cc l-p khc nhau d3a trn m0t tiu chuqn 8!ng d9ng no 8. Cc l-p ny cho8cn th_i 8iVm phn lo9i v2n ch1a bict hay ch1a 815c 8`nh danh.H%th$ng nhQn d9ng t380ng bao g!m ba khu t1.ng eng v-i ba giai 8o9n chbycu sau 8y:

Thu nhQn dZli%u v ti4n xRl. BiVu di'n dZli%u. NhQn d9ng, ra quyct 8`nh.

B$n cch ticp cQn khc nhau trong l thuyct nhQn d9ng l: $i snh m2u d3a trn cc 8mc tr1ng 815c trch chNn. Phn lo9i th$ng k. $i snh c6u trc.Trong cc eng dXng r rng l khng thVchgdng c m0t cch ticp cQn 8.n li8Vphn

lo9i t$i 1u do vQy c,n sRdXng cng m0t lc nhi4u ph1.ng php v cch ticp cQn khc nhau.Do vQy, cc ph1.ng thec phn lo9i tk h5p hay 815c sR dXng khi nhQn d9ng v nay 8 cnhZng kct qu7c triVn vNng d3a trn thict kccc h%th$ng lai (hybrid system) bao g!m nhi4um hnh kct h5p. Vi%c gi7i quyct bi ton nhQn d9ng trong nhZng eng dXng m-i, n7y sinhtrong cu0c s$ng khng chgt9o ra nhZng thch thec v4thuQt gi7i, m cn 8mt ra nhZng yu c,uv4 t$c 80 tnh ton. mc 8iVm chung cba t6t c7nhZng eng dXng 8 l nhZng 8mc 8iVm 8mctr1ng c,n thict th1_ng l nhi4u, khng thVdo chuyn gia 84xu6t, m ph7i 815c trch chNnd3a trn cc thbtXc phn tch dZli%u.


51/68



6.2 Thu nhkn v biYu diEn Mnh6.2.1 Thu nhkn v cc thi[t btthu nhkn Mnh

Cc thict b` thu nhQn 7nh bao g!m camera, scanner cc thict b` thu nhQn ny c thV

cho 7nh 8en trrngCc thict b`thu nhQn 7nh c 2 lo9i chnh eng v-i 2 lo9i 7nh thng dXng Raster, Vector.Cc thict b` thu nhQn 7nh thng th1_ng Raster l camera cc thict b` thu nhQn 7nh

thng th1_ng. Vector l sensor homc bn s$ ho Digitalizer homc 815c chuyVn 8ki tn 7nhRaster.

Nhn chung cc h%th$ng thu nhQn 7nh th3c hi%n 1 qu trnh C7m bicn: bicn 8ki n)ng l15ng quang hNc thnh n)ng l15ng 8i%n. Tkng h5p n)ng l15ng 8i%n thnh 7nh.

6.2.2 BiYu diEn Mnh?nh trn my tnh l kct qu7thu nhQn theo cc ph1.ng php s$ho 815c nhng trong

cc thict b`kOthuQt khc nhau. Qu trnh l1u trZ7nh nhpm 2 mXc 8ch: Tict ki%m b0nh-. Gi7m th_i gian xRl.

Vi%c l1u trZthng tin trong b0nh-c 7nh h1fng r6t l-n 8cn vi%c hiVn th`, in 6n v xRl 7nh 815c xem nh1l 1 tQp h5p cc 8iVm v-i cng kch th1-c ncu sRdXng cng nhi4u 8iVm7nh th bec 7nh cng 8jp, cng m`n v cng thVhi%n r h.n chi tict cba 7nh ng1_i ta gNi 8mc8iVm ny l 80phn gi7i.


52/68


GVHD : ThS. Nguy'n V)n Nga Ch1.ng 7: L3a chNn tiu ch thict kch%th$ng

7.1 GiQi thiNu hNthZngH%th$ng nhQn d9ng biVn s$xe ra, vo c chec n)ng so snh biVn s$xe ra v vo ncu

8ng thi. Sau 8 cho php homc khng cho php xe 8i qua h%th$ng c,n g9t.H%th$ng g!m m0t reader 815c lrp 8mt fcRa chnh. Reader ny 815c kct n$i t-i my

tnh. S.8!tkng qut cba h%th$ng 815c m t7nh1sau:

Hnh 7.1 S3'7kh$i tCng qut c)a h+th$ng

7.2 Nguyn trc ho_t Tdng cca hNthZngHo9t 80ng cba h%th$ng ny 815c tm trt nh1sau: Xe vo 8ng v`tr sao cho camera szn

sng chXp biVn s$xe. Sau 8, ng1_i kiVm sot xe socho qut thitag thng qua 8,u 8Nc thitag. Khi 8 7nh t380ng 815c chXp tncamera v 815c l1u 7nh trn my tnh 8VxRl. Ticp

theo, biVn s$xe so815c phn tch v 81a ra 8ng v-i biVn s$xe th3c tc. Cng v-i 8 l mthisohiVn th`cng lc v-i 7nh cba biVn s$xe. Khi xe ra th thao tc t1.ng t3lc vo v mytnh t380ng so snh hai dZli%u g!m biVn s$xe v m thic trng kh-p lc vo khng, ncuc th cho xe ra.

7.3 Cc tiu ch v cc lba chKn phPRng n thi[t k[

Hnh 7.2 S3'7kh$i thi;t k;h+th$ng vo ra RFID


53/68



H%th$ng g!m 2 ph,n : Ph,n ceng : Reader RFID v kh$i giao ticp. Ph,n m4m : XRl 7nh vict trn my tnh.

KHtI THO BI{N

TONCTC,WINDOWS,NG|T RS232

TN HISUT}VDK

HI~N THIDTAG,CHTP ?NHV X]L ?NH

XM HA?NH,NHPHN

?NH

TRCH VNGCHWA BI~N SC

CCH LY K T

TRONG BI~N SC

LDU D"LIAUNHMN DHNG

SO SNHV[I D"LIAU C

S%N

G]I D"LIAU

SBUFF = B XUCNGVDK

NHMN DHNG KTD'C CCH

LY

BEGIN

G]I D"LIAU

SBUFF = BXUCNG VDK

END

S

S


54/68



7.3.1 Ph]n cXngThict kcm0t h%th$ng RFID 8.n gi7n co kh7n)ng:

Nc v hiVn th`dZli%u tntag RFID r!i hiVn th`ra LCD. C thVtruy4n dZli%u ln my tnh v ng15c l9i. Khi c tn hi%u nhQn tnm9ch trung tm th 8i4u khiVn 80ng c.8Vnng v h9

c,n g9t.V-i yu c,u nh1 trn, ph,n ceng so g!m 3 kh$i: kh$i xR l trung tm, kh$i 8Nctransponder v kh$i giao ticp my tnh.

v KhZi x\l trung tmYu c,u thict kc: t$c 80cao, nhi4u tnh n)ng, gi thnh h5p l, c ngn ngZlQp trnh

hdtr5 ng1_i dng. PhPRng n 1: HNvi 8i4u khiVn 8051.

Phkbicn, gi thnh th6p, t$c 80th6p, t tnh n)ng, kh7n)ng ch$ng nhi'u th6p. Ngn ngZlQp trnh: sRdXng ngn ngZAssembly, C, Bascom.

PhPRng n 2: Vi 8i4u khiVn PIC

T$c 80cao, gi thnh h5p l. C tch h5p szn ADC, PWM 8!ng th_i hd tr5cc chuqn giao ticp thng

dXng nh1: UART, I2C.

Ngn ngZlQp trnh: Assembly, C.ChNn vi xR l PIC v t$c 808Nc nhanh, gi thnh vna ph7i, c thV sRdXng

ngn ngZC dng ph,n m4m CCS, trnh bin d`ch ny c hm hdtr5cho vi%c 8Nc vghi RFID, c cc hm 8Vgiao ticp my tnh.v KhZi TKc RFID(Reader)

Yu c]u thi[t k[: c thV8Nc dZli%u tntag fkho7ng cach g,n ( nhvh.n 10cm), gi c7h5p ly. PhPRng n 1: dng chip EM4095 cba hng EM Microelectronic

L lo9i chip c thVghi/8Nc tag. Gi thnh th6p. T,n s$tn100 8cn 150 kHz. Kho7ng cch 8Nc g,n.

PhPRng n 2: dng chip U2270B cba hng Atmel. L lo9i chip c thVghi/8Nc. Ho9t 80ng ft,n s$tn100 kHz 8cn 150 kHz. Gi thnh 8rt h.n so v-i EM4095. ChNn chip EM4095 v gi thnh vna ph7i, ph h5p v-i yu c,u thict kc.

7.3.2 Ph]n mUmYu c,u thict kcch1.ng trinh xRl 7nh : .n gi7n, d'sRdXng. Th3c hi%n 8,y 8bcc tnh n)ng cba ph,n m4m xRl 7nh.

L3a chNn ngn ngZlQp trnh C++.


55/68


GVHD : ThS. Nguy'n V)n Nga Ch1.ng 8 : NhQn di%n biVn s$xe dng t1.ng quan

8.1 Tgng quanvTPRng quan cho

T1.ng quan cho l m0t ph1.ng php tiu chuqn 8nh gi mec 80 cc m$i t1.ngquan. Hy xem xt hai chudi x (i) v y(i) khi i = 0,1,2 ... N-1. t1.ng quan R 815c 8`nh nghsal :

Tr1_ng h5p mx v my l nhZng ph1.ng ti%n cba chudi t1.ng eng. Ncu f trn 815ctnh cho t6t c7cc s3chQm tr'd = 0,1,2, ... N-1 sau 8 kct qu7trong m0t lo9t cc m$i t1.ngquan cho cba hai l,n chi4u di nh1chudi ban 8,u.

Ph9m vi cba t1.ng quan r v chi4u di cba chudi t1.ng quan cho c thVl t h.n so

v-i N, v dXnh1cc mXc tiu c thVl chuqn ha s3t1.ng quan s3th_i gian ngrn. Cc m2us$trong biVu thec trn phXc vXchuqn ha cc h%s$t1.ng quan nh1vQy m -1


56/68



8.3 Quy trnh nhkn d_ng biYn sZxe8.3.1 Thu nhkn Mnh.

Qu trnh thu nhQn 7nh trong h%th$ng 815c th3c hi%n t380ng thng qua m0tcamera gim st, 7nh thu 815c c thVchia lm 2 d9ng l chgchXp vng biVn v baog!m biVn cng m0t ph,n cba 8ui xe. ?nh c,n 815c xRl tr1-c khi nhQn d9ng bpng

cch 81a 7nh v47nh xm sau 8 t)ng 80t1.ng ph7n bpng cn bpng xm.

8.3.2 Trch chKn vng chXa biYn sZxe.MVc Tch: Tnbec 7nh chXp 815c trong b1-c thu nhQn 7nh, p dXng cc thuQt ton

trch ra 815c vng 7nh nhvnh6t chea biVn s$.Cc phPRng php: c nhi4u ph1.ng php khc nhau 8V th3c hi%n nhi%m vX ny

nh1ng t6t c784u c thVqui v43 ph1.ng php chnh sau 8y:- Ph1.ng php dng chuyVn 8ki Hough: d3a vo 8mc tr1ng c9nh bin trch 815c, p

dXng cc ph1.ng php xc 8`nh 81_ng thung nh1php bicn 8ki Hough 8Vpht hi%n cc cmp81_ng thung g,n song song ghp thnh m0t 7nh biVn s$.

- Ph1.ng php hnh thi hNc: d3a vo 8mc tr1ng hnh thi cba biVn s$xe nh1mu src,80sng, s38$i xeng 8Vxc 8`nh v trch ra 7nh biVn s$.- Ph1.ng php kh-p m2u: xem biVn s$ l m0t 8$i t15ng c khung n4n ring v sR

dXng cc cRa skd 8Vtrch tnng 8$i t15ng 81a qua m9ng noron (neural network), tr tu%nhnt9o (artificial intelligence) chung h9n 8Vphn lo9i c ph7i l vng biVn s$hay khng. Nghinceu ny sosRdXng ph1.ng php hnh thi hNc.

8.3.2.1 PhPRng php hnh thi hKcNdi dung cca phPRng php: D3a vo 8mc tr1ng quan trNng l biVn s$xe my c 80

sng (tec mec xm khi chuyVn bec 7nh v4d9ng xm) l t1.ng 8$i khc so v-i cc vng khc

trong bec 7nh, clng nh1s3phn b$mec xm l kh 8!ng 84u trn biVn s$v v vQy khi 815cnh`phn ho, vng biVn s$l m0t 8$i t15ng c 8mc th hnh thi, c thVphn bi%t 815c v-icc vng khc . Nh1vQy cc b1-c th3c hi%n f8y l:

- Xc 8`nh ng1wng xm. Th3c ch6t l khng c ph1.ng php no chNn cho 8ngng1wng xm 8Vth3c hi%n. Thay vo 8, ng1wng xm so815c qut trong m0t kho7ng no 8.Thng qua l15c 8!xm ta nhQn th6y vng biVn s$ th1_ng so c 80 sng t1.ng 8$i l-n (tn130-200) v vQy ta soxc 8`nh l15c 8!xm l-n nh6t trong kho7ng ny v ng1wng xm c,nchNn sothu0c vng ny nh_8 ta sogi7m 815c th_i gian lmp tm ng1wng xm.

Hnh 8.2 Dnh xm '"u vo Hnh 8.3 L0Kc '7xm c)a b/c nh xm


57/68



- LNc cc nhi'u (salt and pepper noise) gy 7nh h1fng x6u t-i 8$i t15ng biVn

Documents

HỆ-THỐNG-NHẬN-DẠNG-BIỂN-SỐ-XE-ỨNG-DỤNG-CÔNG-NGHỆ-XỬ-LÝ-ẢNH