THIT B VIBA S 904 1. S khi v ch tiu k thut ca thit b vi ba s RMD 9041.1.S d khi ca thit b vi ba s RMD-904

RMD-

Hng AWA sn xut cc h thng vi ba s lm vic cc bng tn 900MHz, 1500MHz v 1800MHz. Cc thit b v tuyn vi ba s ca hng ny s dng phng thc iu ch pha vung gc (QPSK - Quadrature Phase Shift Keying). H thng cho php truyn dn cc lung 2Mb/s, 22Mb/s v 42Mb/s m ng HDB3 mc cng sut +37dBm (5Wat). Cu trc Modul ca thit b cho php d dng bo qun v sa cha. 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.

MY PHT2 2048Kb/s

Khi bng tn c s pht

Khi Kch thch

Khi k cng sut

Khi hin th

diplexerKhi hin th

Tn hiu RF noois ANTEN

2 2048Kb/s

Khi bng tn c s thu

Khi Trung tn thu

Khi bin i h tn

My thu

Hnh 1.1: S khi thit b pht thu

1.2.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: Vi cng sut ra 1w: Cc phng php d phng:

-24 VDC hoc -48 VDC gian. 63w 43w + D phn gm . + D phn gnng. + Phn tp tn s. + Phn tp khng 50.

Tr khng Phi v ANTEN: ANTEN parabol ng knh:

0,9 m; 1,2 m; 1,8 m; 2,4 m.

2. Phn pht

S khi phn pht ca RMD-904 c cho hnh 1.2. My pht RMD-904 gm cc khi chnh sau:DIPLEXER

2 2048Kb/s

KHI BNG TN C S pht

KHI Kch thch

KHI K CNG SUT

RF

KHI HIN TH

Hnh 1.2 . S khi my pht RMD-904

4 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).

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 th. 2.1. 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.

NRZ Output A Clock Output A Clock A: 2048KHz B bi i m n HDB3/NRZ 2048Kb/s HDB3 75Ohm Data A: 2048Kb/s Data B: 2048Kb/s B bi i m n HDB3/NRZ Clock B 2048KHz Clock Output B NRZ Output B 2,2KHz Mcro i ch mc u nh knh nghi v p 4,245Mb/s B b in i n i t ip t h n h s o n g s o n g v m h o vi sa u

B g h p k nh

B n g u n h i n h o

khi k n ch th i ch u

d/dt

Tai nghe u ra b x l ti ni ng u vo k nh nghi v p 0dBm, 600Ohm Tone gi 2KHz i ch mc u nh b ng t c s n khi k n ch th i tn ch u sng mang v tuy RF n

5KHz

i ch mc u nh Tone gi

u vo k nh gi m s t -10dBm 600Ohm

H 1.3: S khi PBA b ng t c s ph t nh n

2.2.Khi kch thchModul kch thch nm trong mt hp kim loi ring lp trn khung my pht. Nguyn l hot ng ca khi c cho hnh 2.4. 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.

T hi s t n u khi b ng tn c s ph t

220 MHz -9dBm

8750 - 959,5 MHz + 8dBm

T i khi khuy ch i cng sut

220 MHz sinwt coswt

Khi i ch QPSK u

VCO Khi t ng h p t s n

Chia 4

Chia 4 Ph t hi n mcT hi b ng n u tn c s ph t khi b ng tn c s ph t

T i gi m s t s c

B t ng h p tn s

Tm dao ng VCO v trn n t ng n

T m ch AGC

H 1.7. S khi ca Modul k th nh ch ch

2.3. Khi khuych i cng sutNguyn l lm vic ca khi c cho hnh 2.5: 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 hai 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. Khi 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.

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

H 1.10. S khi Modul i cng sut PBA nh

2.4. 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. 3. Phn thu 3.1. S khi

KHI HIN TH

2 2048KB/S

KHI BNG TN C S THU

KHI TRUNG TN THU

KHI BIN I H TN

TN HIU RF

KHI NGUN CUNG CP

Hnh 2.6: S my thu

Hnh 3.1: S khi my thu RMD- 904.

My thu vi ba s RMD-904 c nhim v thu sng mang siu cao iu ch pha pht, gii iu ch tn hiu thu khi phc cc tn hiu lung s liu c iu ch. Tn hiu knh nghip v, knh gim st. My thu c 4 Modul chnh c lp trn mt khung my ring. 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). 3.2 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

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. S khi Modul bi i h t nh n n

3.2.1 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 90 0 nh cc mch ghp (thc hin bng mch in).

3.2.2. 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 c cho hnhB chia lp tr v n n ng nhC c chuy n m ch BCDB ss

B lc vng

B dao ng OSC chun

VCO

B chia ECL

H 1.13. S khi m ch 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 3.3. Khi trung tn Nguyn hot ng ca khi trung tn c cho hnh 1.14: 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

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 Khuy i trung tnIF ch

Tm lc trung tn IF Filter

H 1.14. S khi Modul trung t nh n

Khi ny c hai tm mch in:Tm lc trung tn thu, 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. 3.4. 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 3.5. 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. 3.6. 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

NRZ/B Output

Clock/B Output

Clock B 2048KHz

B bi i m n HDB3/NRZ

HDB3 Output 75Ohm 2048Kb/sB bi i m n HDB3/NRZClock/A Output Clock A Output NRZ/A Output NRZ Output A

DATA B: 2048Kb/s

B ph n k nhDATA A: 2048Kb/s

4, 245 Mb/sClock A 2048KHz

B g i i n g u n h i n

+12v T i th p nghe ni Handset

R le

2 KHz

2, 2 KHz

B b in i so ng so ng t h nh n i t ipCLK1 CLK2 Data1 Data2

600ohm u ra k nh nghi v p 0dBm 600 Ohm 600ohm

mc knh t nghi v p

OFF A2

mc loa t

B k h i ph c n g h

mc tone t A1 600ohm u ra k nh gi m s t -10dBm 600 Ohm 2,7 KHz 5 KHz

I

QT hi n u IF thu

B g i iu c h COSTAS

600ohm

35MHz

H 1.15. S khi t b ng t c s thu RxBaseBand nh m n

4 Khi ghp song cng (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 ca DPLERXER gm:Tn hao thun ti nh hn 1,5dB,tn hao ngc nh hn 20dB, rng bng tn danh nh 10 MHz.