1-
1- Qu cng sut:
Phng trnh cn bng :
Ps +Gi Pr = L+ Pc + Pm
Trong :
Ps : Cng sut pht [dBm]
Gi: khuch i ca cc b khuch i trn tuyn [dB]
Pr : nhy my thu [dBm]
L : C ly truyn dn
: H s suy hao ca si [dB/km]
Pc: Suy hao th ng trn tuyn bao gm:
Suy hao do cc mi hn
Suy hao do u ni connector
Suy hao xen r ca cc b b tn sc
Suy hao do cc b xen r bc sng trn ng truyn
Pm: Lng cng sut cn tnh d ra b li s thit thi v cng sut pht sinh
trong qu trnh lm vic ca tuyn hoc s suy gim cht lng ca cc thnh phn
trong h thng.
Bng gi tr d phng khi thit k tuyn WDM theo phng php truyn
thng:
STT
i tng d phng
d tr suy hao (dB)
Ghi ch
1
Cng sut d phng cho thit b pht
4.95
B li s gim m mu mt do s gi ha v s khng hon thin ca thit b.
2
Cng sut d phng cho thit b thu
2.1
B li s gim m mu mt do s gi ha, do hin tng nhy my thu phu thuc
phn cc, nhy my thu ph thuc bc sng v do c tnh khng hon thin ca thit
b.
3
D phng cho thit b MUX/DEMUX
2.2
B li s gim m mu mt do s gi ha, c tnh khng hon thin gy nn xuyn
knh, do ph thuc phn ccca thit b.
4
Cng sut d phng cho si quang:
4.1
Cho s gi ha ca si quang v cc mi hn trn tuyn
3.2
B li s suy hao trn si v cc mi hn.
4.2
Cho nh hng ca tn sc si (CD&PMD)
1.8
B li s thit thi v cng sut gy ra do tn sc ca si quang.
4.3
Cho cc b b tn sc
1.0
B li s thit thi v cng sut gy ra do c tnh b khng hon ho ca cc b b
tn sc.
4.4
Cho nh hng ca cc hiu ng phi thuyn
2
B li s thit thi v cng sut do cc hiu ng phi thuyn SPM, XPM, FWM,
SRS, SBS
4.5
Cho hin tng suy hao ph thuc vo phn cc trong si quang
0.2
B li s thit thi v cng sut do hin tng suy hao ph thuc vo phn cc
trong si quang.
5
Cng sut d phng cho cc b khuch i quang
5.1
Cho nh hng ca c tuyn khuch i khng bng phng ca b khuch i khng bng
phng
3.0
Ph thuc vo bng phng ca ph khuch i
5.2
Cho hin tng khuch i ph thuc phn cc ca b khuch i quang
1.0
B li s suy gim m mu mt do hin tng khuch i ph thuc vo phn cc ca b
khuch i quang
5.3
Cho s gi ha ca b khuch i quang
1.0
Tng cng
22
2- Qu tn sc:
D= d - DCM + d phng
Trong : D l tn sc tng
DCM : b tn sc
d: Khong cch ca chng
d phng 10km
Ch : D
