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i Hc Cng Ngh Thng Tin
BI TP TRUYN DN QUANG
Mt tuyn quang di L=15km, dng si quang SI (50/125m) ! " #$n# %
#it
su't tng "*i =1+, #it su't %i n1=1-.- Si quang ! suy #a tung
3n#=.d4/km (ti =50nm) #6 =2,.d4/km (7 =1800nm), #& s* t9n s:
#'t %i&uM=180;s/nm-km (ti =50nm) #6 M=10;s/nm-km ( 7
=1800nm)-
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i Hc Cng Ngh Thng Tin
*,: !uy hao ghp quang ti u pht . -2*= .L : !uy hao trung "#nh
3=-014%m5 L=*%m6 * %m u ti7n ch8a c mi hn no
SH= 10.logCngsu t
pht quang ban u
P1 = */01
*/= 10.log 4
P1 #$%&'()$ '.'* m+
'( !uy hao ti i)m / m :
SH)= *, + -./ + 5*., = -*., 01
3 5*.,: / %m c , mi hn 6
SH)= 10.logCngsu t pht quang ban u
P1 = -*5,01
-*5, = 10.log 4
P1 #$%&'%(,$ '.,- +
'( !uy hao ti i)m *9 m :
SH*9 = *, +-2*9 + 5*.= *.; 01 =< #/$ /.* 0+
b. 120h s3 t4m l56 7 kho809 cch 9i;a cc t4m l56
>i :
?! : @Ang !uBt pht quang "an u
?r : '( nhy
Lm : Suy hao 0C phDng cho thiEt "F
Lc : Suy hao cGa cc ghp ni'i In JF:
@Ang !uBt pht quang "an u: ?! = -mK =< ?! = * og 3-6 =
01m
?" = 01m 3M-;01m6 3*,+*601 = 9N 01
Suy hao trung "#nh tr7n !Oi quang :
c = P + ! +
m
?" = ?! ?r MLmMLc
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>i :
P :'( !uy hao trung "#nh cGa !Oi quang.
! : Suy hao trung "#nh cGa mi hn tr7n mQi m 3 014m6
m : Suy hao 0C phDng cho cp
c =-+ .*49 + = -.; 014m
@C y gi>i hn "Ri qu cAng !uBt :
L =P b
c =28
4.05 = . m
!ua09 t4?0 c@0 sA dB09 t4m l56 do >uC cD09 sut
chE cho 6hF6 t4uy0 G. Im mt ch509. S3 t4m c@0 cho Iml / t4m
.
- WBi #iZu di #6ng n# t$n, t* " it [ "i ! t#O tuyZn \a tuyn
quang %
G h t9n s: tEng ng
Dchr = Dmat+ 0 = MmatL
= 130psnm!"m # 3$nm # %!&"m
= 31!&ns
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i Hc Cng Ngh Thng Tin
= ;s
d) ju Cng su't \a tn tuyn k#i t#ay "Ei Cng su't "u Q
F = Fsl F`l Lml L
= 10%g(1) l ( G .5d4m ) l 0 l (18 10)d4
= 0 .5 l 28 = 22d4
Suy #a tung 3n# t$n si quang % a= .,05 d4/km
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