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1.4.2. S khi tng qut tng i SPC
SPC: Stored Program Control: iu khin theo chng trnh lu tr/ghi sn
Hnh: s khi tng qut ca tng i SPC
Nhn chung cc tng i SPC c th l tng i tng t hoc s vi dng lng v kt cu a
dng. Hnh v a ra s khi tng qut ca tng i SPC.
C th chia cu trc ca tng i SPC thnh hai h thng chnh:
-
- thoi v h thng x l iu khin.
1.4.2.a) H thng thoi:
H thng thoi c th chia thnh 3 phn h:
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a1)Phn h thu bao v bo hiu thu bao
Phn h thu bao v bo hiu thu bao gm:
- SLIC (Subscribers line Interface Circuit) Mch kt cui ng dy thu bao, thc hin nhm
7 chc nng BORSCHT.
+ B Battery feed:
+ O Over-voltage protection:
+ R Ring:
+ S Supervision:
+ C Coder and decoder:
+ H Hybrid:
+ T Test:
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Cc thit b u cui thu bao c th l analong (tng t) hoc digital (s). Vi
thu bao analog, c 7 chc nng u c thc hin SLIC. Vi thu bao digital, mt s
chc nng c thc hin ngay ti thit b u cui.
- Cc khi chuyn mch tp trung thu bao.
+ Dng tp trung ti thu bao.
+ c thit k theo tng nhm mch SLIC.
+ Ni mch in thu bao ti cc b Tone Gen. v MFR ty vo tng giai on ca cuc
gi.
- Tone Gen. (Tone Generator) B to m bo, c chc nng to cc tn hiu m bo mang
thng ip m mi quay s, Bo bn, Hi m chung,
- MFR (MultiFrequency Receiver) B thu m a tn, c chc nng thu cc tn hiu a ch t
my in thoi n phm a tn.
- LOC (Local Controller) B iu khin giao tip, thc hin cc chc nng:
+ Phn phi cc tn hiu bo hiu ng dy thu bao qua b chuyn mch tp trung ti
thu bao
+ Phn phi cc knh thoi qua b chuyn mch tp trung thu bao
+ Qun l trng thi thu bao
+ iu khin phn phi cc tn hiu bo hiu v cc tn hiu nh thi
+ Lp cc bn tin iu khin truyn ti phn h x l iu khin
+ Nhn v x l cc bn tin iu khin t phn h x l iu khin
+ To cc tn hiu iu khin b chuyn mch tp trung ti thu bao v cc mch kt
cui (SLIC)
a2)Phn h chuyn mch nhm
-
Phn h chuyn mch nhm thng bao gm: mng chuyn mch nhm, b iu khin chuyn
mch v mt s khi chc nng ty thuc vo tng loi tng i.
- Mng chuyn mch: c th l analog/digital, c cng ngh, cu trc v dung lng ty vo loi
tng i v nh sn xut.
- B iu khin chuyn mch, thc hin cc chc nng:
+ Nhn cc bn tin iu khin t phn h x l trung tm
+ X l cc bn tin iu khin v chuyn thnh cc s liu iu khin tng ng sau
a n cc b chuyn mch c th.
+ Thc hin chc nng chn tuyn hoc gii phng tuyn theo yu cu ca cc bn tin
iu khin.
+ C th thc hin mt s chc nng lin quan n lin quan ti vic chn v tch cc
bn tin iu khin thng qua mng chuyn mch.
- Cc thit b khc, thng gm:
+ Thit b to tn hiu nh thi
+ Cc thit b dng chung nh: b nh cc bn ghi t ng tr li, b nh cc a ch
thng gi, thit b chuyn mch nhiu ng.
a3)Phn h trung k v bo hiu trung k
Phn h trung k v bo hiu trung k gm mch giao tip trung k tng t ATIC, mch giao
tip trung k s v cc b iu khin km theo.
- ATIC (Analog Trunk Interface Circuit) Mch giao tip trung k tng t (c th l loi 2 dy
hoc 4 dy), c chc nng ging vi mch giao tip thu bao tng t, tuy nhin c mt vi khc
bit v bo hiu v cp ngun.
- DTIC (Digital Trunk Interface Circuit) - Mch giao tip trung k s, lm nhim v x l tn
hiu trung k s, x l bo hiu trung k. Mch DTIC thc hin nhm 8 chc nng GAZPACHO.
+ G Generation of frame: To khung
+ A Alignment of frame: ng chnh khung
-
+ Z Zero string compression: Nn chui bit 0 lin tip.
+ P Polar conversion: o cc
+ A Alarm: cnh bo
+ C Clock recovery: Ti to xung nh thi (Ti to nhp)
+ H Hunt during frame: Ti ng b
+ O Office signaling: Bo hiu lin i
- Ngoi ra, phn h ny c cc b tch v ghp knh, cc b iu khin nhm trung k LOC
(Local Controller) phi hp vi h thng x l iu khin.
1.4.2.b) H thng x l iu khin
H thng x l iu khin c chia thnh cc phn h:
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b1) Phn h x l v phn phi bo hiu
Phn h x l v phn phi bo hiu thng gm cc thit b thu/pht bo hiu, thc hin chc
nng x l v phn phi bo hiu, cung cp kt qu x l cho cc b iu khin chuyn mch v x l
cuc gi.
-
Ty thuc vo tng loi tng i c th c cc thit b bo hiu knh kt hp CAS Channel
Associated Signaling (cn gi l bo hiu knh ring) hoc bo hiu knh chung CCS Common Channel
Signaling.
a s cc tng i chuyn mch s hin i u xem xt ng dng CCS tng thch vi s
pht trin ca mng vin thng trong tng lai. Tuy nhin, cng cn c thit b CAS lin kt vi cc
h thng hin hnh.
b2) Phn h x l trung tm
Phn h x l trung tm iu hnh ton b hot ng ca tng i thng qua cc b iu khin
cp thp hn (nh cc b LOC trong h thng thoi).
Phn h ny gm b x l trung tm, b nh chnh, b nh chung.
- B x l trung tm:
+ Trao i cc thng tin iu khin vi cc b LOC bng cc bn tin iu khin thng
qua cc Bus h thng (System Bus).
+ X l cc thng tin iu khin nhn c t cc b iu khin LOC trong qu trnh x
l cuc gi v to ra cc bn tin iu khin gi li cc b iu khin iu hnh cc
qu trnh phc v cuc gi.
- B nh chnh MM-Main Memory:
+ Cha chng trnh iu hnh hot ng ca b x l
+ Cha cc thng tin cn thit trong qu trnh x l.
- B nh chung:
+ Cha chng trnh gc ca tng i
+ Cha d liu thu bao, d liu trung k v d liu chung ca tng i.
+ B x l trung tm v cc b iu khin khc c th truy cp b nh chung s dng
cc d liu lu tr ti y.
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b3) Phn h qun l v bo dng
Phn h qun l v bo dng thc hin chc nng qun l hot ng ca ton b tng i thng
qua vic gim st hot ng ca cc b iu khin LOC, b iu khin trung tm v thng qua cc thit
b o th, kim tra.
Cc thit b trong phn h qun l v bo dng gm:
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Phn h ny s a ra cc tn hiu hoc bn tin cnh bo, cc hng dn tng ng theo mi trng
thi ca h thng.
Thit b giao tip ngi-my gip nhn vin vn hnh v cn b k thut c th theo di hot ng
ca h thng v c kh nng giao tip vi h thng thay i cc tham s v ch hot ng ca cc
khi chc nng ca tng i.
1.4.3. S khi tng qut tng i SPC chuyn mch s
Cc tng i SPC chuyn mch s gi chung l H thng chuyn mch s DSS (Digital Switching
Systems) ra i vo na cui th k 20.
DSS l mt h thng tng hp cng ngh cao, tp trung hi t rt nhiu ngnh cng nghip. Ngay
c mt tng i DSS dung lng khng ln cng l mt tng th rt phc tp. Phn ny ch xem xt
DSS mc n gin nht.
Ton b tng i c chia thnh cc phn h:
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Hnh v: S khi tng quan tng i SPC chuyn mch s
1.4.3.a) Phn h ng dng APS (APplication Subsystem)
APS bao gm:
- MDF (Main Distribution Frame): Gi phi dy chnh/Gi u dy/Gi nhp i
+ L trang thit b thc hin kt ni cc ng dy ngoi vi ti cc mch trong h thng
tng i in t s.
-
- SLIC (Subscriber Line Interface Circuit): Mch giao tip ng dy thu bao.
- TSAC (Time Slot Asignment circuit): B phn phi cc tn hiu nh thi, dng gn cc khe
thi gian pht, thu cho tng mch SLIC phc v chc nng m ha v gii m CODEC.
- DLCD (Digital Line concentration Device): B chuyn mch ng dy s, thc hin chc nng:
+ chuyn mch tp trung ti thu bao
+ chuyn mch tn hiu phc v t b DTG
+ chuyn mch ng dy ti b MFR
- DTG (Digital Tone Generator): B to tn hiu m tn dng s
- MFR (Multi Frequency Receiver): B thu tn hiu chn s a tn
- LOC (Local Controller): B iu khin cc b/B iu khin vng
- ATIC (Analog Trunk Inteface Circuit): Mch giao tip trung k tng t,
+ dng kt cui cc ng trung k tng t.
+ Cc ATIC c t chc thnh tng nhm, mi nhm do mt b LOC iu khin.
- MUX/DEMUX (MUltipleXer v DEMUltipleXer): B tch v ghp knh.
+ MUX/DEMUX c chc nng ghp tn hiu t cc mch ATIC theo hng vo v tch
tn hiu theo hng ra a ti tng mch ATIC.
- DDF (Digital Distribution Frame): Gi phn phi tn hiu s/Gi u ni cc lung s.
+u ni cc tuyn tn hiu s PCM gia phn h ng dng APS vi phn h chuyn mch
SwNS.
- DTIC (Digital Trunk Interface Circuit): Mch giao tip truyn dn s.
+Thc hin nhm 8 chc nng GAZPACHO.
1.4.3.b) Phn h chuyn mch SwNS (Switching Net work Subsystem)
Bao gm cc thit b mng chuyn mch SwN Switching Network, cn
gi l TDSwN (Time Division Switching Network) Mng chuyn mch phn
thi v module ng h chun BT Base Time.
b1) TDSwN Mng chuyn mch phn thi
TDSwN thc hin cc chc nng c bn sau:
-
+ Chuyn mch to knh kt ni tm thi lin kt cc module ng dng phc
v cho qu trnh x l cuc gi.
+ iu khin kt ni knh t cc kt cui, bao gm c vic h tr cho cc cuc gi
a ng
+ To cc knh s liu c nh hoc bn c nh truyn cc bn tin iu khin
trong h thng.
+ H tr chc nng OA&M
b2) BT ng h chun
BT thng l b dao ng c n nh cao v tn s v cc b chia to
co tn hiu xung nhp cung cp cho hot ng ca cc b chuyn mch s, cc
thit b truyn dn tn hiu s v cc b phn phi thi gian TSAC ca phn h
ng dng.
1.4.3.c) Phn h x l trung tm CPS (Central Processing Subsystem)
CPS gm b iu khin trung tm CC (Central Control) v b nh chnh MM (Main Memory).
- CC m nhn chc nng iu khin hot ng ca ton b tng i, CC c th c cu trc n
x l hoc a x l.
- MM lu chng trnh v cc kt qu x l, MM c kh nng truy cp ti b nh chung
nhn thm d liu thu bao v bng nh tuyn hoc ti nguyn khi cn thit.
1.4.3.d) Phn h bo hiu SiGS (SiGnaling Subsystem)
Phn h SiGS m nhn chc nng x l v phn phi bo hiu, iu khin cc qu trnh chn,
tch bo hiu.
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Tn hiu CAS khi qua chuyn mch s cng c chuyn thnh dng s ging cc tn hiu tin
tc khc v c phi hp vi hai pha ca mng bng cc b thch nghi.
Bo hiu CCS dng trao i gia cc h thng DSS vi nhau.
1.4.3.e) Phn h ngoi vi iu khin PCS (Peripheral Control System)
Phn h ngoi vi iu khin c nhim v phi hp gia cc giao din v phn h x l trung tm
nhm tng cng nng lc x l cho ton b h thng tng i.
PCS gm cc b Distributor, Scanner, v Marker.
- Distributor: B phn phi bo hiu.
+ Thc hin vic chuyn i cc thng tin bo hiu t dng ny sang dng khc. V d:
chuyn cc thng tin bo hiu di dng bn tin sang cc dng s liu trn knh.
+ Phn phi cc bn tin bo hiu v cc lnh iu khin.
- Scanner: B qut.
+ Pht hin, xc nh v bo co cho CC cc thng tin v cc trng thi v a ch trn
ng dy thu bao v trung k.
- Marker: B iu khin chuyn mch cc b.
+ Thc hin u ni chuyn mch trong phm vi nh, gim lu lng cho trng chuyn
mch chnh.
+ m bn tin iu khin t phn h x l trung tm CPS chuyn thnh nhng s liu
iu khin chuyn mch.
1.4.3.f) Phn h iu hnh qun l v bo dng OA&MS (Operation,
Administration & Maintenance Subsystem)
Phn h OA&MS thng gm cc thit b thc hin cc chc nng:
-
+ T ng theo di hot ng ca h thng,
+ iu khin cc qu trnh chuyn i d phng,
+ Cnh bo khi c s c,
+ Cung cp kh nng iu khin t xa v bo dng t xa tp trung ti trung tm bo dng.
1.5. X l cuc gi trong tng i in t s
kha cnh x l ti tng i, c th phn cc cuc gi thnh 4 loi:
- Cuc gi ni b: L cuc gi xy ra gia hai thu bao cng thuc mt tng i.
- Cuc gi ra: L cuc gi gia thu bao thuc tng i ang xt ti thu bao thuc mt tng i
khc.
- Cuc gi vo: L cuc gi gia thu bao mt tng i khc n thu bao thuc tng i ang
xt.
- Cuc gi chuyn tip: L cuc gi gia hai thu bao thuc hai tng i trn mng nhng i qua
tng i ang xt.
Chng ta s xem xt nguyn l hot ng ca tng i thng qua vic thc hin x l bn loi
cuc gi nu trn.
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1.5.1. Cuc gi ni b:
(1) Tn hiu nhc my:
+ Khi thu bao mun thc hin cuc gi, thu bao s thc hin thao tc nhc my.
+ Thao tc ny to ra tn hiu bo hiu khi u cuc gi Off-hook Signal/hang off (bng cch
gii phng mt tip im nm trn thit b in thoi ca ch gi, lm cho mch vng thu bao
vi tng i kn mch. Khi c dng in mt chiu cp cho my in thoi)
+ Chc nng gim st S ca mch ng dy thu bao (SLIC) s pht hin v chuyn ti cc
thit b lin quan.
(2) Xc nh thu bao ch gi
Sau khi tn hiu nhc my c pht hin bi mch in ng dy thu bao, tng i thc hin
vic xc nh thu bao ch gi.
+ B iu khin mch in thu bao s xc nh ch s thit b EN (Equipment Number) ca thu
bao ch gi.
-
+ Tin hnh bin dch EN thnh s danh b DN (Directory Number) ca thu bao thng qua bng
bin dch.
+ Trn c s kt qu bin dch, tng i s c c nhng thng tin quan trng phc v cho cuc
gi nh quyn lin lc, kiu my in thoi, cc dch v ca thu bao, (gi chung l c tnh
ca thu bao ch gi). Nu thu bao c quyn c thit lp lin lc th chuyn sang bc 3.
(3) Cp pht b nh v kt ni vi cc thit b dng chung
+ Tng i cp mt bn ghi cuc gi (Call record) l mt vng nh cn cho sut tin trnh cuc
gi trong lu tr mi chi tit lin quan.
+ u ni thu bao ch gi vi b to m bo cp m mi quay s cho thu bao.
+ u ni thu bao vi b thu a ch ri.
(4) Thu v lu gi cc s DN
+ Khi nhn c m mi quay s, thu bao ch gi tin hnh pht cc ch s a ch DN ca thu
bao b gi bng cch quay a s (my in thoi c) hoc n s.
+ Ngay khi nhn c ch s a ch u tin, b iu khin trung tm yu cu b iu khin thu
bao ngt mch cp m mi quay s.
+ Cc ch s ny c tng i thu v lu tr vo mt vng nh trong b nh.
(5) Phn tch s
+ Sau khi thu c cc ch s a ch DN ca thu bao b gi, h thng iu khin cn phi phn
tch cc ch s ny xc nh hng ca cuc gi hin hnh.
+ Tin phn tch (phn tch ch s tin nh): phn tch ch s a ch u tin nhn c xc
nh loi cuc gi: cuc gi ni ht, cuc gi ra, hay cuc gi dch v c bit.
+ Trng hp ny l cuc gi ni ht, thu bao b gi thuc tng i ang xt, nn tng i tin
hnh qu trnh phn tch, bin dch t s danh b DN nhn c thnh ch s thit b EN ca thu
bao b gi. Ngha l s xc nh thu bao b gi thuc b tp trung thu bao no, do b iu khin
mch in thu bao no qun l v ch s kt cui thu bao b gi.
+ H thng iu khin kim tra trng thi thu bao b gi: iu khin trung tm yu cu b iu
khin thu bao ca thu bao b gi thc hin kim tra trng thi thu bao b gi: bn, ri, Nu
thu bao b gi ri th s thc hin to knh kt ni gia hai thu bao.
-
(6) Chuyn mch to knh
+ Sau khi xc nh r c hai mch in thu bao ch gi v thu bao g gi, h thng iu khin
ca tng i s chn mt ng kt ni gia hai thu bao qua trng chuyn mch ca tng i
bng cc thut ton chn ng thch hp.
(7) Cp dng chung v tn hiu hi m chung
+ Sau khi to tuyn ni gia hai mch in ca hai thu bao, tng i pht tn hiu chung cho
thu bao b gi ng thi gi hi m chung cho thu bao ch gi.
Tn hiu chung c cp pht qua cc Rle chung ca mch ng dy thu bao.
Hi m chung c cp t b to tone qua tuyn thoi hng v ca thu bao ch gi.
(8) Thu bao b gi nhc my tr li
+ Khi thu bao ch gi nhc my tr li, tng i s thu c tn hiu tr li ca thu bao b gi.
Tng i tin hnh ct dng chung v hi m chung khi knh kt ni gia hai thu bao.
+ Hai thu bao bt u m thoi
(9) Gim st cuc gi
+ Trong khi m thoi, chc nng gim st c thc hin nhm xc nh cc v pht hin tn
hiu gii phng cuc gi khi mt trong hai thu bao t my.
(10) Gii phng cuc gi
+ Khi cc thu bao t my, thit b iu khin s gii phng tt c cc thit b v b nh tham
gia phc v kh dng cho mt cuc gi khc.
+ Chng trnh tnh cc s kt thc tnh cc cho cuc gi v thc hin lu thng tin cc vo
thit b nh.
1.5.2. Cuc gi ra
Bc u ca cuc gi ra tng t nh cuc gi ni b cho n khi phn tch cc ch s a ch
(1) Tn hiu nhc my
(2) Xc nh thu bao ch gi
(3) Cp pht b nh v kt ni vi cc thit b dng chung
(4) Thu v lu gi cc s DN
(5) Phn tch s
+ Sau khi thu c cc ch s a ch DN ca thu bao b gi, h thng iu khin cn phi phn
tch cc ch s ny xc nh hng ca cuc gi hin hnh.
-
+ Tin phn tch (phn tch ch s tin nh): phn tch ch s a ch u tin nhn c xc
nh loi cuc gi: cuc gi ni ht, cuc gi ra, hay cuc gi dch v c bit. Trong trng hp
ny l cuc gi ra.
(6) Phn tch, tm tuyn ni thch hp
+ Sau khi xc nh c loi cuc gi, tng i tin hnh phn tch, tm tuyn ni thch hp cho
cuc gi ra (c th l cuc gi trong vng, cuc gi lin tnh hay cuc gi ra quc t). Ngha
l tm hng i ph hp cho cuc gi v chn ng trung k ri phc v cuc gi ra.
+ Khi chim c ng trung k ri, hai tng i thc hin cc thng tin bo hiu cn thit
phc v cho vic thit lp tuyn ni gia hai tng i.
(7) To tuyn cho cuc gi ra
+ Sau khi xc nh c tuyn i cho cuc gi ra, tng i s thc hin qu trnh bo hiu lin
i vi tng i i phng trao i cc thng tin lin quan n cuc gi .
+ Khi kt thc qu trnh bo hiu, tng i ch gi thc hin thit lp to tuyn ni gia thu
bao ch gi vi knh thoi va chim c trn ng trung k u ni gia hai tng i.
Sau , tng i b gi s thc hin qu trnh x l cuc gi vo. Nu thu bao b gi ri, tng i
b gi s thit lp tuyn ni cp hi m chung cho thu bao ch gi qua knh trung k va chim
c.
1.5.3. Cuc gi vo
(1) Tng i b gi nhn bit c cuc gi vo
+ Gia hai tng i lun c trang b cc lung PCM v lun tn ti cc phng php bo hiu
nht nh: bo hiu knh chung, bo hiu knh ring.
+ Thng qua qu trnh bo hiu lin i, tng i s nhn bit c c cuc gi n.
+ Qu trnh bo hiu lin i cng gip trao i cc thng tin v a ch thu bao b gi.
(2) Tng i thc hin qu trnh tin phn tch, phn tch, bin dch v to tuyn.
+ Tng i thc hin tin phn tch: phn tch cc ch s a ch u tin. Xc nh c y l
cuc gi vo.
+ Sau khi xc nh c y l cuc gi ti mt thu bao thuc qun l ca mnh, tng i s tin
hnh x l tip theo din ra nh cuc gi ni b. Ch khc l tng i phi thng bo v trng thi,
c tnh thu bao b gi cho tng i i phng qua bo hiu lin i to tuyn ni thch hp
gia hai tng i.
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1.5.4. Cuc gi chuyn tip
Cuc gi chuyn tip ging vi cuc gi vo, tuy nhin sau khi thc hin phn tch ch s tin
nh s nhn thy ch s ny khng phi l ca mnh.
Tng i s thc hin tm kim trong c s d liu ca mnh v xc nh c ch s ny l ca
tng i ln cn.
Tip theo tng i s x l nh cuc gi ra.
1.5.5. Tng kt hot ng ca tng i trong cc cuc gi
Vi mi cuc gi, tin trnh x l ca tng i s khc nhau:
- Cuc gi ni b: (Phn tch ch s tin nh) (phn tch) (bin dch) (to tuyn m thoi)
- Cuc gi ra: (Phn tch ch s tin nh) (phn tch) (tm chn tuyn i thch hp cho cuc gi)
(bo hiu lin i) (to tuyn m thoi).
- Cuc gi vo: (bo hiu lin i) (phn tch ch s tin nh) (phn tch) (bin dch) (to tuyn
m thoi)
- Cuc gi chuyn tip: (bo hiu lin i) (phn tch ch s tin nh) (phn tch) (tm chn tuyn
i thch hp cho cuc gi) (bo hiu lin i) (to tuyn m thoi)
