May Thu Phat Vi Ba So

Chu Ngc Tn KTVT-K50

Thit k mn hc:Truyn dn v tuyn s

B GIO DC & O TO TRNG I HC GIAO THNG VN TI-C S II KHOA IN T-------

THIT K MN HC TRUYN DN V TUYN S

TI:TM HIU THIT B VI BA S RMD-904

GVHD: TS.V TRNG SN SVTT: CHU NGC TN LP: KTVT-K50 MSV: 5051022069

TP.H CH MINH 24/05/2012

Tm hiu v my thu pht v tuyn s RMD-904

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Chu Ngc Tn KTVT-K50

Thit k mn hc:Truyn dn v tuyn s M U

S pht trin ca nn kinh t x hi ng thi do s pht trin ca khoa hc cng ngh i hi dung lng truyn dn thng tin p ng ngy cng phi cung cp nhiu cc dch v cho khch hng. Chnh v vy cc thit b vin thng nhiu knh cn phi a vo mng phc v cho nhu cu ngy cng cao ca khch hng nh thng tin v tinh, thng tin do ng,thng tin quang, h thng truyn dn thng tin vi ba. H thng truyn dn thng tin Vi ba s vi nhng c im u vit: Lm vic tn s cao nn d dng tp trung nng lng, do vy c th ch to c an ten c tnh phng hng cao; d trin khai v lp t tuyn truyn dn nhanh chng; gi thnh h hn so vi thng tin quang, tuyn hot ng khng ngng khi c thm ho, tai nn (bo l, l t);thng tin vi ba c th pht mt s im khc nhau trong cng mt hng, ging nh thng tin qung b.V th h thng ny ang c s dng rng ri nc ta. Thit b thu pht sng v tuyn l mt trong cc b phn ca h thng vi ba s. Trong c RMD-904 ca hng AWA thit b thu pht ang c s dng hu ht cc trung tm vin thng tnh, huyn Vit Nam. Trong iu kin thi gian v kh nng c hn ca bn thn, v vy bi lm khng trnh khi nhng sai st. Knh mong c s gip qu bu ca thy gio b mn. Em xin chn thnh cm n! TP.H Ch Minh24/05/2012


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Chu Ngc Tn KTVT-K50


MC LC

M U ............................................................................................................................. 2 MC LC ........................................................................................................................... 3 TM HIU V THIT B VI BA S RMD-904 ................................................................ 4 I.Gii thiu chung v my thu pht v tuyn s RMD-904 ................................................ 4 II.Ch tiu k thut ca thit b vi ba s RMD-904 ............................................................. 5 III.iu ch trong thit b vi ba s RMD-904 ..................................................................... 6 IV.Phn pht ........................................................................................................................ 7 4.1.Khi bng tn c s pht ............................................................................................ 8 4.2.Khi kch thch ........................................................................................................... 8 4.3.Khi khuych i cng sut ....................................................................................... 8 4.4.Khi hin th ............................................................................................................... 9 4.5.Nguyn l lm vic ca my pht RMD-904 ............................................................ 9 V.Phn thu ......................................................................................................................... 10 5.1.S khi ................................................................................................................ 10 5.2.1.B bin i h tn ............................................................................................. 11 5.2.2.B tng hp tn s ............................................................................................ 11 5.3.Khi trung tn .......................................................................................................... 12 5.4. Khi bng tn c s................................................................................................. 13 5.5.Khi cp ngun ........................................................................................................ 14 5.6.Khi hin th ............................................................................................................. 14 5.7.Nguyn l lm vic ca my thu v tuyn s RMD-904 ......................................... 14 VI.Khi ghp song cng (Diplexer) .................................................................................. 14 VII.ng dng ca thit b Vi ba s RMD-904 .................................................................. 15 TI LIU THAM KHO ................................................................................................. 16


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Chu Ngc Tn KTVT-K50


TM HIU V THIT B VI BA S RMD-904 I.Gii thiu chung v my thu pht v tuyn s RMD-904 Thit b AWA l thit b truyn dn Vi ba s bng hp dng cn ng b do AUSTRALIA sn xut v c nhp vo Vit Nam di dng SKD hoc CKD.Thit b Vi ba AWA hin nay nc ta c mt s loi: +RMD 904 : 820 MHz - 960 MHz. +RMD 1502 : Truyn dn 1 lung s 2,048 Mbt/s. +RMD1504: Truyn dn 2 lung s 2,048 Mbt/s. +RMD 1808: Truyn dn 4 lung s 2,048 Mbt/s. Cc thit b vi ba s ny c th c s dng t chc cc tuyn n hay nhiu trm cho thng tin ng trc hoc ng nhnh. C th t chc chng theo cu hnh truyn dn khng d phng vi mt my pht v my thu tng pha. Cng c th t chc chng dng truyn dn c d phng t c tin cy cao hn. Tn ti cc phng thc d phng sau y thit b:D phng m, d phng nng, phn tp tn s, phn tp khng gian. trm c d phng khi xy ra s c th my thu v my pht d phng c chuyn mch bo v (Protecttion Switch) chuyn vo ch cng tc. Thit b RMD 904 l thit b u tin c a vo lp t,khai thc trn mng truyn dn vi ba s Vit Nam.y l thit b vi ba s bng thng hp.Hin nay, hu ht cc tnh huyn ang khai thc v s dng thit b ny.


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Chu Ngc Tn KTVT-K50


Hnh 1.1: S khi thit b thu pht

II.Ch tiu k thut ca thit b vi ba s RMD-904 THNG S. Dung lng: Tn s v tuyn: Cng sut ra ni ANTEN: Ngng thu: Ti BER = 10 exp-6. Ti BER=10 exp-3. iu ch tn hiu s: u vo s liu: CH TIU K THUT. 2*2Mb/s (60 knh thoi). 820 MHz - 960 MHz. +37dBm. -90dBm. -93dBm. -94 dBm. OQPSK. HDB3 2,048Mbit/s, 75 khng cn bng. FM. 2 dB 3 dB. 0 dBm. >40 dB. 2 KHz. FM. +2 dB3dB -10dBm -10dBm

iu ch knh nghip v: p tuyn tn s knh nghip v 300 2200 Hz: Mc vo/ra knh nghip v 600: T s tn hiu/tp m S/N: Tn s tone gi: iu ch knh gim st: p tuyn tn s knh gim st 2,7Khz - 5,0Khz: Mc vo knh gim st (600): Mc ra knh gim st (600): Ngun cung cp cho thit bi in p DC: Cng sut tiu th ton b trn mt my u cui: +Vi cng sut ra 5 w:63W +Vi cng sut ra 1w:43W

-24 VDC hoc -48 VDC


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Chu Ngc Tn KTVT-K50 Cc phng php d phng:

Thit k mn hc:Truyn dn v tuyn s + D phngm . + D phngnng. + Phn tp tn s. + Phn tp khng gian. 50. 0,9 m; 1,2 m; 1,8 m; 2,4 m.

Tr khng Phi v ANTEN: ANTEN parabol ng knh:

III.iu ch trong thit b vi ba s RMD-904 My thu pht vi ba s s dng kiu iu ch sOQPSK iu ch pha 4 trng thi m ho trc tip(OfSet Quadrature Phase Shif Keying). B iu ch OQPSK c gi l iu ch pha cu phng. Mi mt lung s liu c x l bng mch iu khin, hn ch mc v i qua b lc thng thp. Hai lung s liu ny c a vo hai b trn cn bng vi tn s sng mang trung tn IF 220MHz iu ch 2PSK ca hai nhnh, c a vo b cng kt hp hai tn hiu ca hai b trn s to c ra tn hiu OQPSK.Tn hiu sng mang tn s 220MHz c ly t b dao ng thch anh 73,333 MHz v c nhn ba (bi tn bc 3).

Da ta In

+Da ta In

220MHz VCO

V n g k h o ph a PLL

Chia 4 K/ CS

Chia 4

T i ALC


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Chu Ngc Tn KTVT-K50

Thit k mn hc:Truyn dn v tuyn s Hnh3.1.Khi iu ch OQPSK.

B chuyn i m t n cc sang lng cc (m NRZ) vi bin 0,7 V do hai i t trong mch 9V 4 (9V3) vi c hai lung s hiu A v lung s hiu B. Sau cc lung s ny i qua mng RC gim chm cc sn xung sao cho t s y c th iu chnh tht bng nhau u ra ca b bin i m. Hai tn hiu sng mang 220MHz c cn bng cch iu chnh mc mt chiu(DC) trong 2 b trn c s dng iu chnh b trong b khuch i 9N2 v 9 N3. Tc l ln lt iu chnh cc chit p 9R57 v 9R58. ng thi mt trong hai tn hiu sng mang 220 MHz c a qua b lm lch pha 900 sau mi c a vo b iu ch pha: 2PSK (nguyn l iu ch 2PSK c hc trong phn c s vi ba). Tn hiu ra ca mi b iu khin 2PSK c tn s 220MHz v pha c lch nhau 900 ri tip tc c a qua b tng hp (trn hai sng mang c iu ch ny vi nhau). u ra cu n s thu c tn hiu sng mang IF 220 MHz v c iu ch pha cu phng (OQPSK) a qua b khuch i tuyn tnh tn hiu sng mang ny c khuch i v bin in p a sang b trn nng tn. IV.Phn pht S khi phn pht ca RMD 904 c cho hnh 4.1.

DIPLEXER

KHI BNG TN C S PHT

KHI KCH THCH

KHI K CNG SUT

RF

KHI HIN TH

Hnh 4.1: S khi my pht Hnh v 3.1: S khi my pht RMD-904 My pht RMD-904 gm c cc khi chnh sau y :Tm hiu v my thu pht v tuyn s RMD-904 Page 7

Chu Ngc Tn KTVT-K50


Khi bng tn c s pht (TxBaseBand). Khi kch thch (Exciter). Khi khuch i cng sut pht PA (Power Amplifier). Tm mch hin th my pht (Tx Display).

4.1.Khi bng tn c s pht Khi thc hin bn chc nng chnh sau: X l tn hiu bng tn c s chnh (s), X l tn hiu bng tn c s ph (tng t), Cp ngun mt chiu, Khuych i logarit v cc hin th cnh bo. Nguyn l hot ng: Khi thc hin nhn 2 lung 2048Kb/s m HDB3 t tng i hoc my ghp knh hoc cc thit b khc n ghp thnh mt lung 4,245Mb/s m NRZ, sau c ngu nhin ho, chia thnh 2 lung 2,1225 Mb/s, c m ho vi sai trc khi a khi iu ch. Tn hiu knh nghip v, knh gim st c ghp thnh tn hiu bng tn c s ph 5KHz a n iu tn vo sng mang RF. 4.2.Khi kch thch Modul kch thch nm trong mt hp kim loi ring lp trn khung my pht. Khi kch thch thc hin iu ch hai lung s liu sau khi c m ho vi sai vo sng mang trung tn 220MHz theo phng php iu ch OQPSK. Sau tn hiu IF pht c trn nng tn vi tn s sng mang RF nm trong bng tn cng tc. Sng mang RF s dng trn nng tn c to ra t mt b dao ng iu khin in p VCO v vng iu khin tng hp tn s. Tn hiu sau khi trn nng tn c lc, khuych i v khng ch mc +8dBm a ti khi khuych i cng sut. Tn hiu bng tn c s ph 5KHz gm tn hiu knh nghip v, tn hiu knh gim st, tn hiu tone c truyn i bng cch iu tn vo sng mang cao tn RF vi di tn cc i 15KHz trc khi ti b trn nng tn tn hiu IF 220MHz. Kt qu u ra ca b trn nng tn tn hiu RF pht cha cc thng tin ca lung s t tng i hoc cc thit b khc v cc thng tin nghip v. Modul kch thch gm ba khi chc nng chnh: +Khi iu ch OQPSK. +Khi trn nng tn. +Khi tng hp tn s. 4.3.Khi khuych i cng sut Nguyn l lm vic ca khi c cho hnh 3.2: Khi khuch i cng sut bao gm 4 tng khuch i tuyn tnh siu cao tn dng Transistor lng cc m bo khuch i cng sut t +8dBm ln mc (30 - 37dBm) theo yu cu. H s khuch i ca haiTm hiu v my thu pht v tuyn s RMD-904 Page 8

Chu Ngc Tn KTVT-K50


tng khuch i cui c th iu khin c bng chit p. nh thin cho 4 tng khuych i cng sut bng tm nh thin ring.

T hi RF n u

875,0 -959,5 MHz

t khi k th ch ch

+37dBm T i o v mch AGC

Khuych i cng sut PBA

Hnh 2.4 Khi kch thch Hnh 4.2: Khi khuch i cng sut

H 1.10. S khi Modul i cng sut PBA nhKhi cn thc hin cch li gia my pht v phi anten bng mt b cch sng (Isolator). Nh b cch sng ny m m bo trnh hin tng phn x sng khi h ti. Trch mt phn sng cao tn to tn hiu ALC iu khin cc tng khuych i trong khi kch thch m bo mc tn hiu vo +8dBm.Do nh thin cho cc tng khuych i cng sut bng tm nh thin ring dng cc Transistor nh mt ngun dng n nh m cng sut ra ca my pht c n nh cao.Tn hiu o vo ni ti khi kch thch bng u ni loi SMB. Tn hiu ra ni qua b cch sng (Isolator) bng cc u ni dng SMA tr khng 50. 4.4.Khi hin th Tm hin th c lp rp PANEL pha trc my pht . Tm c ba n LED cnh bo mu v mt b hin th 20 vch LED ch th cc mc cng sut pht hin thi. Khi c nhim v nhn tt c cc tn hiu ch th v trng thi lm vic ca h thng truyn dn iu khin cc n cnh bo tng ng sng. My c thit k hin th trng thi s c tn hiu phn pht v hin th mc cng sut pht. 4.5.Nguyn l lm vic ca my pht RMD-904 Trn c s cc khi chc nng, my pht RMD904 ln lt thc hin: nhn hai lung s 2048Kb/s m HDB3 ghp thnh lung 4,245Mb/s, ngu nhin ho, bin i ni tip thnh song, m ho vi sai, iu ch vo sng mang trung tn IF pht 220MHz theo phng php OQPSK, trn nng tn thnh tn hiu RF trong gii tn pht, khuych i tn hiu RF t mc cng sut pht 5 Wat (37dBm). X l tn hiu knh nghip v v knh gim st to thnh tn hiu bng tn c s ph 5KHz iu tn vo sng mang RF trc khi trn nng tn tn hiu IF pht 220MHz. Gim st, x l, bin i cc tn hiu to ra cc tn hiu th hin v s c, mc tn hiu iu khin hin thTm hiu v my thu pht v tuyn s RMD-904 Page 9

Chu Ngc Tn KTVT-K50 V.Phn thu


5.1.S khi Hu ht cc ni ghp vi bn ngoi c thc hin thc hin qua Jack ni dng ch D.Ngoi ra cn c hai u ni 75 loi SMB ni tn hiu kim tra biu mt knh I v knh Q, mt u ni 75 loi SMB ly ra ng h khi phc 4,245Mb/s. C th thay i tn s thu v tuyn bng cc chuyn mch BCD vi phn gii 100KHz. My thu RMD-904 gm c cc khi chnh:Modul bin i h tn - Convertor Modul, Modul trung tn - IF Modul, Tm mch bng tn c s thu RxBaseBand, Tm mch hin th (Rx Display).

KHI HIN TH

2 2048KB/S

KHI BNG TN C S THU

KHI TRUNG TN THU

KHI BIN I H TN

T/H RF

KHI NGUN CUNG CP

Hnh 5.1:S khi my thu 5.2.Khi bin i h tn Khi ny c hai phn : Mt phn bin i h tn v tuyn v mt b tng hp tn s. S khi ca Modul cho hnh 5.2

Hnh 2.6: S my thu

Hnh 3.1: S khi my thu RMD- 904.


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Chu Ngc Tn KTVT-K50


lo i t s nh n

B t ng h p tn s

VCOT i gi m Ph t hi n s t s c mc

RF thu t DIPLEXER

Trung t n IF 35M Hz

Chia 4

Chia 4

T ng h p t s n

Tm bi h t n i n

H 1.12. Modul bin bi h n nh Hnh 5.2: SS khi Modul inh itnt

5.2.1.B bin i h tn Tm bin i h tn c hai tng khuych i v tuyn v tng trn ng thi loi tr tn s nh. Cc b khuych i v tuyn c c mch iu khin nh thin. Tng u c thch ng m bo tp m nh (Tng khuych i tp m nh LNA) cn tng th hai c nhim v gim s thay i khuych i trong bng tn. n nh hot ng cc phn t tch cc c nui bi ngun dng n nh. Cc b trn gm hai b trn cn bng v hai b ghp dch pha 900. B trn bin i h tn, tn hiu thu vo trung tn 35MHz. B trn m bo loi tr 20dB tn s nh v suy hao bin i 8dB. Vic loi tr tn s nh t c bng chia dao ng ni thnh hai phn ng pha v a n hai b trn cn bng. ng thi cng a n hai b trn ny tn hiu tn s v tuyn c chia i nhng lch pha 900 nh cc mch ghp (thc hin bng mch in). 5.2.2.B tng hp tn s Nh b tng hp tn s m ta c th d dng iu chnh tn s thu vi phn gii 100KHz bng cc chuyn mch xoay BCD. B tng hp tn s lm vic trn c s vng kho pha.


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Chu Ngc Tn KTVT-K50


B chia lp tr v n n ng nhC c chuy n m ch BCD

B ss

B lc vng

B dao ng OSC chun

VCO

B chia ECL

Hnh 1.13. b khi m tn s H 5.3: S S tng hpch t h p t s nh ng n Cng ging nh b tng hp tn s my pht, cc b chuyn mch xoay BCD iu khin b chia lp trnh chn knh. B dao ng chun l b dao ng thch anh iu khin c v vng cha b chia tc cao k ngh ECL v b chia lp trnh. 5.3.Khi trung tn Nguyn l hot ng ca khi trung tn c cho hnh 4.4: Modul trung tn nhn tn hiu trung tn IF = 35 MHz t b bin i h tn lc cng nh to ra tn hiu mc c nh cho cc mch bng tn c s. Modul ny xc nh rng bng tn ca h thng thu, n cha cc mch o mc v tuyn v to ra cc tn hiu cnh bo.


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Chu Ngc Tn KTVT-K50


T hi IF t i n u RxBase Band

T hi IF t n u khi bi n i h t n

B t ch sng AGCo mc RF

K Loga Gi m s t s c RF

Tm Khuych i trung tnIF

Tm lc trung tn IF Filter

H 1.14. S khi Modul trung t nh n Hnh 5.4: S Modul trung tn

Khi ny c hai tm mch in:Tm lc trung tn thu v tm khuych i trung tn thu. Tm lc trung tn thu: Tm ny nhn tn hiu u ra ca b bin i h tnv m bo chn lc ca my thu. B lc bao gm hai mng lc LC : mt mng 4 cc v mt mng 3 cc. Gia chng l tng khuych i m. gim tp m tn hiu, u vo c khuych i bi mt tng khuych i bao gm Transistor lng cc v Transistor trng J-FET c cc cng ni t. B khuych i trung tn thu: B khuych i nhn tn hiu vo vi s thay i c th kh ln (-105dBm n -50dBm) u vo my thu v to ra tn hiu ra c s thay i nh hn 2dB. B khuych i trung tn thu cng m bo in p o a ra vi thay i t l vi mc tn hiu trung tn. in p o ny nhn c t mch x l AGC bng b khuych i Logarit. 5.4. Khi bng tn c s Chc nng ca khi bng tn c s thu l nhn tn hiu trung tn 35MHz khi phc li tn hiu bng tn c s s (khi phc cc lung s 2048Kb/s c gi i t pha pht) v cc tn hiu knh nghip v, gim st, tone gi bng tn c s ph. Cc lung s tn hiu trung tn c iu ch OQPSK trong kh tn hiu bng tn c s ph c iu tn. khi phc li cc thng tin ni trn tm bng tn c s thu phi thc hin cc chc nng sau:Khi phc sng mang, Giao tip s liu, Khi phc ng h, Gii m ho vi sai v bin i s liu song song thnh ni tip, Kh ngu nhin ho, Phn knh s, Bin i m NRZ vo HDB3, Cp ngun


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Chu Ngc Tn KTVT-K50


5.5.Khi cp ngun Khi cp ngun thc hin bin i ngun DC v n p theo nguyn l iu ch rng xung ging nh ngun my pht cung cp cc mc in p cho my thu: 5V; +10V; +36V hn na cc in p ra cng c tinh n bi cc b n nh in p. Tuy nhin v cng sut tiu th nh nn b ngun lm vic trong gii t - 20VDC n - 60VDC khng cn phi s dng cc jc chuyn i ch ngun cung cp u vo -24V, -48V nh my pht. Ngun cung cp cng c bo v qu p v qu dng. 5.6.Khi hin th Tm hiu th c lp panel trc ca my thu. C 3 n LED v mt hin th 20LED vch ch th mc cng sut v tuyt thu. 5.7.Nguyn l lm vic ca my thu v tuyn s RMD-904 Sng mang siu cao tn t an ten qua fi , qua phn hng an ten c a vo u vo my thu, qua khuch i siu cao tn, ti i tn. Tn s sng mang c h thp xung tn s trung tn v c khuch i tip da qua bng tn c s thc hin gii iu ch v x l tn hiu s, tch lung ri a cc knh v vi tr tng ng. VI.Khi ghp song cng (Diplexer)

Tn hiu RF t my pht

Tn hao 0,4dB

RF

Tn hiu RF ti my thu

DIPLEXERRF

Ni vi ANTEN

Tn hao 0,4dB

Hnh 6.1: S Diplexer

DIPLEXER cho php kt hp my pht v my thu cng mt ANTEN, DIPLEXER m bo chn lc v gim cc tiu nhi ca knh ln cn. Cc thng s caTm hiu v my thu pht v tuyn s RMD-904 Page 14

Chu Ngc Tn KTVT-K50


DPLERXER gm:Tn hao thun ti nh hn 1,5dB,tn hao ngc nh hn 20dB, rng bng tn danh nh 10 MHz. VII.ng dng ca thit b Vi ba s RMD-904 -Thit b AWA l thit b truyn dn Vi ba s bng hp dng cn ng b do AUSTRALIA sn xut v c nhp vo Vit Nam di dng SKD hoc CKD. -Cc thit b vi ba s ny c th c s dng t chc cc tuyn n hay nhiu trm cho thng tin ng trc hoc ng nhnh. C th t chc chng theo cu hnh truyn dn khng d phng vi mt my pht v my thu tng pha. Cng c th t chc chng dng truyn dn c d phng t c tin cy cao hn. -Thit b RMD 904 l thit b u tin c a vo lp t,khai thc trn mng truyn dn vi ba s Vit Nam.y l thit b vi ba s bng thng hp.Hin nay, hu ht cc tnh huyn ang khai thc v s dng thit b ny.


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Chu Ngc Tn KTVT-K50


DANH MC T VIT TT T vit tt Convertor Modul DIPLEXER Exciter IF Modul Isolator HDB3 OQPSK T gc Convertor Modul DIPLEXER Exciter IF Modul Isolator OfSet Quadrature Phase Shif Keying Ngha ting vit Modul bin i h tn Khi ghp song cng Khi kch thch Modul trung tn B cch sng M ng mt cao iu ch pha 4 trng thi m ho trc tip Chuyn mch bo v Khi khuch i cng sut pht PA Tm mch bng tn c s thu Tm mch hin th my pht M nh phn khng tr v khng Khi bng tn c s pht B dao ng b iu khin bi in p

Protecttion Switch Protecttion Switch PA Power Amplifier RxBaseBand RxBaseBand Tx Display None return zero TxBaseBand Voltage Controlled Oscilator

NRZ

VCO

TI LIU THAM KHO 1.Bi ging Truyn dn v tuyn sTc gi:Tin s V Trng Sn. 2.Thit b vi ba s AWA ...Tc gi: Ca tng CTBCVT . 3.Gio trnh c s truyn dn vi ba sTc gi: Nguyn Phm Anh Dng.


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May Thu Phat Vi Ba So