Điều chế TTL và ứng dụng trong thông tin quang

BAO CAO TOM
TAT
DE
TAI
NCKH CAP DHQG
1-Ten
de tai;
Dieu che TTL va
ung
dung trong thong tin quang
Mas6QT-99-05.
2-
Chu tri de tai: PGS.TS Vu
nhu Cuong
3-
Cac can bp phoi hap
Thac Sy
Truofng
vu
B^ng
Giang
C\x
nhan
Chir diic
Trinh
- NCV Pham thi Tuyet
- Mot so sinh vien khoa CN DT-VT
4-
Tom tat
ket
qua nghien

curu
Tim
hieu ve
dudng
truyen thong tin quang
Tim
hieu ve dieu che TTL,
ling
dung phat va thu
tin
hieu quang da
du'Oc
dieu
che
hkng phuong
phap dieu che noi
Che tao bo phat va thu
tin
hieu quang.
5-
Cac ket qua dat
dupe
Tong quan thong tin quang- Giao
trinh
TTQ
- Thiet ke
lap
rap mot so phan
tii
cho he thong truyen

dSn tin
hieu thong tin
quang.
Xay dung cac bai thuc tap TTQ ve cac van
d6
tren.
Dao tao 4
cii
nhan CN DT-VT ve thong tin quang hoc
6-
Tinh
hinh kinh
phi
de tai
Da
dupe
chi dung nhu du toan
Ha ngi ngay 20 thdng 5 nam 2003
Chii
tri
de tai
PGS.TS Vu nhu Cuong
Xac nhan
ciia co
quan
chii
irVjk^
'i !/
LJ
'^\

">
GS.ISKH:
t^/%^4i€^€^t
^iyncl ^^nwf
truan
Xac nhan
ciia
.hoa
hoc tu nhien
^^ Mu.Suu'^S.
MAW
OAl
HOC
Oi/'••
.
^tA
HA
NOi
TRUNG TAM ' .ONG
TIN
THU
ViEN
\^ ^~'-
BAO CAO TONG KET
DE TAI CAP DAI HOC QUOC
GIA
''Dieu che
TTL
vd
ung dung trong Thong tin quang

K'
Giai thieu
ve de tai
I- Ten de tai:
"Dieu
che
TTL va
img
dung trong Thong tin
quang"
Ma
so
QT 99-05
II-
Chu
tri
de tai: POSTS Vu nhu
Cuang
Luc
luong
tham gia
d6
tai:
Cac can bo phoi hop
- Thac Sy
Truong
vu Bang Giang
Cu nhan Chu
due
Trinh

- NCV Pham thi Tuyet
- Mot so sinh vien khoa CN DT-VT
III-
Thai gian thuc hien: 24 thang 1999-2000
IV-
Xuat
xii ciia
de tai
Do nhu cau thong tin doi hoi truyen dung luong ngay cang
16n,
toe
do truyen
ngay eang nhanh den muc eae he thong truyen din truyen thong : eap doi
xiing
, eap
dong true, song vi ba, thong tin ve tinh kh6ng the dap
ling
duae.
Dam
duong
nhiem
vu nay ehi eo the
la
he thong thong tin quang hoc
vai
song mang tan so
Idn
10^-10^
Hz
va toe do eao c6 the nang dan

len tir
Mbit/s-Gbit/s va den Tbit/s.Cho den nay thong
tin quang da trai qua bon the he. The he
thii
tu dang
duoc thuong
mai
hoa,
duoc
dac
trung
bing
cong nghe ghep kenh quang DWDM eo su dung khuyech dai quang
sgi
pha tap Erbium. Toe do truyen
din
eo the dat tai hang tram Gbit/s. The he
thii
nam
dang trong thu nghiem
vdi
day hua hen. The he nay la the he giai quyet van de tan
sic
ciia sai
quang duae dae trung bing cong nghe truyen din Soliton. Co the noi he thong
TTQ
CO
nhung uu viet khong the thay the
v6 toe
do

truy6n
din,
vt
dung luong eung
nhu chat luong thong tin.
Thong tin quang nhap vao Viet nam vao dau nhung nam 90
cua
the ky 20.
Nam
1991
Bo mon Quang va Quang pho khoa Vat Ly truang DHTH cu nay la truang
DHKHTN bat dau nghien euu ma ehuyen de TTQ.' Nam 1996 Khoa CNDT - VT
truang DHKHTN ra dai
,
tiep tue nghien euu dao tao cac
cir
nhan DT - VT
\'ai
cac
khoa
luan
ve TTQ, xay dung cac
thi
nghiem, thuc hanh ve TTQ cho SV va hoc vien
eao hoc
Viee
nim bit cong nghe mai, dao tao cac ehuyen gia ve
llnh
vue nay la mot
doi hoi cap thiet. Do

chinh
la ly do
hinh
rhanh de tai nay vao nam 1998.
V- Muc tieu
ciia
de tai bao
gom:
1.
Tim
hieu viee ung dung dieu che TTL trong TTQ
vi
he thong truyen din TTQ
la he truyen din so.
2.
Thifi't
ke lip rap cac mach thu phat
tin
hieu quang dieu che TTL
3.
Xay
dung mot so bai thuc tap vi TTQ
4.
Dao tao cac cu
nhSn
DT-VT lam khoa luan ve TTQ.
B.
Cac Mt
qua
daf dirge

1-
T6ng
quan th6ng tin quang- Giao trinh TTQ Phu
luc
1
2-
Thifi't
ke lip rap mot so phin tu cho
ht ihong
truyen din
tin
hieu th6ng tin
quang, Va
xSy
dung cac bai thuc tap TTQ ve cac van de
trSn.
Phu luc 2
He th6'ng thong tin
sgi
quang TTL/EFO la mot cong cu tuyet hao de de phat
tin
hieu so TTL dieu che
cuong
do anh sang
phai
tu nguong quang( la
died
phat quang
LED hoac diod laser LD ). Sa 66
khoi

cua he thong phat va thu
tin
hieu TTL
dugc m6
ta
or hinh
sau
Hinh
1
Sa 66 khoi cua he thong thu phat so quang TTL
lOMbit/s
Nguon quang dugc gin vao diu noi FC de ghep noi vai sgi quang. Ve phia
diu thu sgi quang dugc noi vai dau do quang thong qua diu n6i FC. Diu do quang
chira m6t
Ph6 to di 6t PIN ( hoac APD )
. Dong
dien ra cua diu do quang dugc
khuye'ch dai bing mot bg
khuyecli
dai ehuyen
ticp cung
cap
m6t
dien ap
a loi
ra. Sau
do la
m6t b6
khuye'ch dai dai rgng va mot mach nguon TTL tuang
thich.

Di thuc
hidn
kiem tra tren cac mach, khoi mach con
ehira
eon
chtJa
mot may phat xungthay doi
duae
tin
s6
Hinh 2
HelhuctapTTQl
oc
uo
OMbit/s
SV
Q
C5
iOOOuF
T T
R9 RIO -±r -±r
Ik
•^
•^>^
C4
TPl
R8
Ik
P.7
U2B

100
T
U2A
100
"I"
ai
b^.
UiC
r T
U6
UlA
150
lOO
UIB R4
74HC1'1
(U2A,U2B
74HCO0
Cuii^uiB.tric;
Rb
£20
•^ne
lOuF
CI
us
hi
-N
RZ
1
R3
10

Hinh
3.
Sado
nguyen ly may phat xung quang 10Mbps
L May phat:
So 66 nguyen ly cua may phat xung quang duoc trinh bay tren
hinh
3. May
phat (transmitter) bao gom may phat xung TIL va bo
dit^u
che dong bom cho
laser
diode.
a. May phat xung TTL tan so bien doi:
May phat xung TTL (TTL Generator) tan so bien doi c6 dai tan so c6 the thay
d6i
tir
500kHz den 5MHz hoac tu
IMHz
den
lOMHz.
Trong ca dai tan so,
ti Ic giua
d6
rong va do r5ng xung ia 1:1 va khong thay d6i
vdi
bien do 5V. May phat xung
dira
tren ca
so*

vi mach
74HC14.
May phat xung eo nhiem vu tao
tin
hieu so
mSu
cho qua
trinh truyen din qua cap
sgfi
quang,
trong truang
hgp
c6
tin
hieu thong tin so thuc cau
noi (jumper) U4-U6
dugc tach
ra va
tin
hieu thong tin dugc dua thang vao bo dieu che
laser
vh.
dugc
kiem tra tai
didm
TPl .
I-Rnh
4 cho thay dang
tin
hieu

loi
ra
ciia
may
phat xung TTL (a) va dang
tin
hieu thu dugc sau khi qua he truyen
dfm
quang (b) tai
toe
do 5Mbps
(tin
hieu dugc do qua day do suy hao 10
Ian).
b.
Bo dieu che dong bom cho laser diode:
Bp
dieu
che
dong
bo'ni olio
laser diode
sir
dung vi mach
74HC00
cung cap
dong bam cho laser diode LD gom dong
tin
hieu ac tren nen mot
chicu

dc c6 the thay
doi
bien
do
bing
bien tra
R2
• Dong bam cho laser diode dugc kiem ua tai diem
TF^2
th6n«
qua sut the tren dien tra tai laser
R^
(10
Q).
Hinh
5
lh6 hicn ii'n hieu
bom vao
laser gom dong dc va ac.
Laser diode
a
day la module laser don mot phat
a buoc
song
1310nm
c6
ddu
noi connector FC. Module phat dugc noi
vdi
module thu photodiodc c6 dau noi

connector FC thong qua adaptor quang va day nhay
sgi
quang (Fiber)
2.
May rhu :
Sa do nguyen ly cua may thu (Receiver) xung quang trinh buy tren
hinh
6.
Module
tliu
su dung
a
day c6 tien khuech dai
ehuyen
tra khang
gdn
ben trong
(in-situ) boat dong vdi bang thong tdi da
150MHz,
do nhay thu
-37dBm.
Tin
hieu
tliu
Hinh
4:
Tin
hieu loi ra
ciia
may phat

xung TTL (a) va
tin
hieu thu dugc sau
khi qua he truyen
ddn
quang (b) vdi toe
do 5Mbps.
Hinh
5:
Tin
hieu
bo"m
vao laser:
I^^=40mA,
I,,-20mA
,
'
dugc tu PIN photodiode sau khi qua bo tien khuech dai (c6 the
kiem ira lai
diem
'IIM
)
di vao mach sua dang xung tren ca sd IC MC
10116.
Dang
tin
hieu bi
meo
tren
dirdng

truyen dugc
phue
hoi dan sau khi di qua cac
tiing ciia
IC sua dang. Tin hieu nay
c6
the
kiem
ira
d diem
kiem
tra TP4. Sau do,
tin
hieu dugc di qua phan khuech dai cong suat
(buffer) tren ca sd transistor
2N2905
va cudi
cluing
duae sua dang lai
Ian nun
bdi
IC
74HC14. Cac
tfn
hieu TTL loi ra cd pha trung va ngugc pha vdi
tin
hieu loi vao dugc
dua ra qua cong
PI
va P2. Hinh 7 bieu dien cac tin hieu loi ra nay d tdc do

10Mbps.
i/3:ci
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ICl
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v^^
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1/3IC1

IPS
01,
02:
2^1905
Z)l
1-iH-Zi-i
Hinh
6:
Sa do nguyen ly cua may thu xung quang
Nlid CO b6
tien khuech dai do nhay
eao
va do khuech dai
16*n
cung nhu cac bg
phan sira
dang
tin
hieu dan
dfin
nen
t^n
sd
tin
hieu
Idi
vao may phat cd the thay doi
trong
mdt
dai

rdng
(500kHz
-^
5MHz) ma ti
le
do rgng va do
rdng
xung
viln
dugc dam
bao
a
loi ra may thu. Hinh 9 la dang
tin
hieu TIL d dau ra may phat xung va
tin hieu
thu dugc d dau ra cua may thu quang vdi tan sd 500kHz. He thdng thu phat quang
cung cd the hoat dong d
tiin
sd thap ( dai KHz).
Hinh 7:
Tin
hieu d hai loi ra
ciia
may thu
4dc
do 10Mbps.
3.
.Vlay
do cong suat quang:

May do cong suat quang loi ra
ciia
LED.
laser
diode cho phep do cong sua't
anh sang d budc song i300nm vdi hai dai do
0->lm\V
va
1-rlOmVV
(do chmh xac
±5%).
May do
sir
dung
ddu
do
PLN
photodiode InGAsP cd connector quang FC va
adaptor quang
ihuan
tien cho
viec
do cong suat loi ra
ciia
module phat quang hoc, Ket
qua do dirge hien thi tren man tinh
ihi
Idng.
May do cong suat quang dugc nudi
b^ng

nguon pin 9V thuan tien cho viec do dac km dong.
4.
Bg suy hao quang:
Bg suy hao quang su dung sgi quang dan mode
9/125um
cd gan connector
quang FC va adaptor quang thuan lien cho viec su dung trong mang thong tin quang.
Do suy hao cd dinh hi
lOdB
cho budc song 1300nm (cd the thay
ddi
do suy hao
khi
c&n
tliiet).
5.
Cac ung dung dao tao
vc
thong tin quang
ciia
he thi nghiem he thdng
tin quang sgi sd hoa 10Mbps:
a)
Giiip
hoc vien nhan biei cac
linh
kien
,
thiet bi ca ban trong he thdng thong
tin quang ( may

phai
quang
(E/0),
may thu quang
(0/E).
module
ihu phai
quang, may
do cong suat quang, bg suy hao quang, )
b) Do dac trung cong
sual
quang
Idi
ra phu
ihugc
dong
kicli ciia
module phat
quang d che do
kich
b;ing
dong xung. Do cong suai quang Idi ra
ciia module
phat d
bucic
song
1300nm.
c)
Tim
hie'u ve may phat xung TTL trong mot dai

tan
sd rgng
(500kHz
tdi
lOMHz).
lim
hieu ve nguyen ly dieu
bieii
theo cudng do cho laser diode.
d)
Tim hiCu
ve qua trinh thu tin hieu sd TTL qua sgi quang: khuech dai
iin
hieu,
sua dang tin hieu. khuech dai cong suat, de khoi phuc dang tin hieu.
e)
'nuc
hanh thiet ke dudng
truydn
sgi quang dan gian,
tinh
toan do suy hao
ciia
dudng truyen. do du
trff
cong suat,
0
Tliuc
hanh truyen din qua cap sgi quang cac
loai

tin hieu sd
lieu,
tin hieu
thoai
duae
ma hoa PCM, Manchester,
2.
Bg bien dieu PCM va thuc hanh ma hoa Manchester:
B6
bien dieu PCM va thuc hanh ma hoa Manchester ket hgp vdi thiet bi
thi
nghidm
thdng tin quang sgi sd hoa tdc do 10Mbps (lam thiet bi dau cudi quang)
dtrgc
trinh bay
trSn hinh
12.
Hlah
12:
Bg bien dieu PCM va thuc hanh ma hoa Manchester ket hgp
vdi thiet bi
thi
nghiem thdng tin quang sgi sd hoa tdc do 10Mbps.
a) He thdng
di^u
che PCM:
Ky thuat
didu
che
PCMjhuc

hien qua trinh ehuyen doi
tin
hieu thoai
tuong
tu
thanh luong PCM sd tdc do 64
Kb/s
la mot ky thuat dugc su dung kha pho bien trong
Iinh
vue truyen thong hien nay. Trong he thdng dieu che PCM,
chiing
tdi da su dung vi
mach MC 3057. Day
la chip
codec dugc su dung rong rai trong cong nghiep thdng tin
lien lac. He thdng cd
the'
chia thanh cac khoi
chinh
nhu tren
hinh
13.
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Hinh
13: Sadd khoi cua bg
bien
dieu PCM va thuc hanh ma hoa Manchester.

1.
Khdi tao
xung nhip (TIMING):
Xung nhip cung
c^'p
cho he thdng gom: xung nhip chu (Master clock), xung
nhip tao khung (TX frame):
tdn
sd 8 KHz, xung nhip bit (bit clock):
tiin
so
64
KHz.
Cac xung nhip dugc tao ra tu khoi tao xung nhip dung thach anh va su dung mach CD
4040 de thuc hien chia tan sd cung
cS'p
cho he thdng.
2.
Khoi dieu che PCM (COMPANDED PCM):
Viec dieu che PCM dugc
thirc
hien nhd su dung vi mach CODECMC 3057. vi
mach nay thuc hien dieu che PCM theo
luat
A, hoat dong vdi cac nguon xung nhip
dugc cung cap bdi
klidi
tao xung nhip cua he thdng.
Tin
hieu dua vao de thuc hien

dieu che cd thi la
tin
hieu
hinh
sin diing de khao sat, hay
tin
hieu thoai dua vao loi vao
Mic in. Cac
tin
hieu nay cd bien do khoang
IV-
SV^^^va
dugc
Igc trude
bang mach
Igc
chdng chdng pho cd dai thdng 300
-
3400Hz. Cac
tin
hieu Analog tren sau khi dugc
dieu che de tao thanh luong PCM 64Kb/s dugc truyen tren mdi trudng
truyen
la mot
sgi cap quang dan mode vdi thiet bi
d^u
cudi quang la thiet bi
thi
nghiem thong tin
quang sgi so hoa tdc

dd
10Mbps.
Tai nai thu.
tin
hieu thu se'dugc dua den khdi PLL de tach xung nhip dong ho
(khoi nay su dung vi mach
CD4046)
va sau do xung nhip dugc su dung de thuc hien
lay
mc\u tin
hieu thu, tao lai tin hieu PCM phat. Luong PCM sau khi tao lai dugc dua
den Codec va Codec se thuc hien viec giai dieu che de thu lai
tin
hieu thoai ban dau.
Trong he thdng nay Codec hoat dong d che do dong bg, cac xung nhip RX frame va
RX bit clock dugc cung cap
bdi
xung nhip tach ra
tij"
lu6ng PCM nhan dugc.
I_
Hinh
14: Sa do nguyen iy bg bien dieu PCM va mii hoa Manchester
3.
Khdi ma hoa va giai ma Manchester
(MANCHESTERCODING
and DECODING):
Di tang dd tin cay,
tinh
hieu qua va kha nang dinh thai khi truyen du lieu sd

la
thudng six dung loai ma dudng(line coding) la ma Manchester. Trong he
ihdng
nay,
viec thuc hien ma hoa Manchester luong data PCM
64
Kb/s dugc thuc hien dc dang
nhd
sir
dung vi mach 74LS86 ket hgp vdi xung nhip bit 256Kb/s.
Tin
hieu sau khi
dugc ma hoa Manchester cung se dugc
truyen
tren moi trudng
truyen
la sai quang dan
mode vdi thiet bi dau cudi quang la thiet bi thf nghiem thdng tin quang sgi sd hoa tdc
do iOMbps. Tai nai thu ta cung tien hanh tach xung nhip va lay
m5u
de
tai
tao
ludng
PCM ban dau
tir
luong PCM dugc ma hoa Manchester.
Hinh
14 trinh bay sa dd mach dien cua he thdng. Mot sd ket qua thu dugc cua he
thdng dugc

irinh
bay tren cac hinh 15a. 15b,
15c,
15d. Cac hinh nay cho
tliay
dang tin
hieu sin
ifin
md phdng
tin
hieu thoai,
tin
hieu sin tiin dugc dieu che PCM. tin hieu
PCM trude va sau khi truyen qua cap quang,
tin
hieu PCM dirge ma hoa Manchester
va tin hieu sin tan thu dugc sau
klii
dieu che PCM va truyen qua cap sgi quang vdi
Ihiet
bi
dfiu
cudi la thiet bi thi nghiem thdng tin quang sgi sd hoa tdc do 10 Mbps. Cac
tin
hieu nay dugc do tai cac diem do khac nhau cua bg ma hoa, thuc hanh bien dieu.
Ket qua thu dugc
tir
he thdng phii hgp vdi cac
chufin
yeu cau doi vdi he

tiuyen
d3n
PCM va quang.
a)
b)
:??^'"^"''!?^T^^'Wirf^
'•A.;?'
^^'f ;.'
'i^'iyu4^^im^m-\
c)
cl)
Hinh
15: a) Tin hieu sin
tiin
ban dau (tren) va
tin
hieu sau khi
diroc dicu che
PCM (dudi).
b) Tin hieu PCM
tructe
(tren) va sau (dudi)
khi liuyeu
qua cap
quanii,
c) Ludng
tin hieu
PCM dugc ma hoa Manchester
trir()c
(tren;

\a sau
(duiu)
kh
truyen qua cap quang.
d) Tin hieu sin tan ban dau (tren) va tin hieu
ihu
duoc sau
khi giai dieu che
PCM cd su dung mdi trudng truyen
diln
quang (dudi).
3.
Cac
urng
dung dao tao ve thong tin quang
ciia
he
thi
nghiem do thdng sd linh
kien quang dien
tiir,
thuc hanh bien dieu:
1.
Giup hoc vien thuc hanh cac phep do (ghep noi vi
tinh)
cac dac trung ca ban cua
LED,
laser diode va module phat
(juang
hoc nhu:

a) Do dac
.
trung cong suat quang loi ra - dong bam dc
(P-I)
d nhiet dd phdng va tai
cac nhiet dd khac nhau, xem chi tiet
ti^g ph^n
cua dd
thi.
b) Do dac trung dong - the
(I-V).
c) Do
phan
bd trudng xa (phan bd khong.
gian ciia chiim
tia laser) (P-A) d cac hudng
khac nhau
ciia
mat
phang
ehuyen tiep p-n cua LED, LD so vdi dfiu thu photodiode.
2.
Giiip
hoc vien
tim
hieu qua trinh bien dieu va ma hoa
tin
hieu thoai vdi mdi trudng
truyen
dan

la cap dien va cap quang:
a) Thuc hanh bien dieu PCM
tin
hieu thoai va giai bien dieu PCM cho mot kenh thoai
khi
sir
dung mdi trudng truyen dan la cap dien va cap quang, so sanh cac ket qua thu
dugc.
b) Thuc hanh ma hoa Manchester
tin
hieu PCM va giai ma hoa khi
sir
dung mdi
trudtig
truyen din la cap dien va cap quang, so sanh cac ket qua thu dugc.
c) Thuc hanh'bien dieu, ma hoa vdi
tin
hieu sin tan mau va vdi tm hieu thoai thuc tu
Micro.
IIL
Kha nang mo rgng thiet ke he thf nghiem
co
sd ve thong tin quang sgi sd hoa
tdc do IOMbps va do thong
sdcac
linh kien quang dien tu:
- Thiet bi
thi
nghiem thong tin quang sgi sd hoa tdc do IOMbps cd ihi thiet ke
cho module thu phat quang hoc da mot hoat dong d budc song 850nm (che tao module

thu quang cd
ti6n
khuech dai ben trong) di cd the thuc hanh do tan
sac
sgi quang.
- Thiet bi do cac thdng sd linh kien quang dien tu cd ihi thiet ke vdi card bien
ddi
AD/DA tdc do eao (12-bit) cho phep do phan giai do eao
han,
tang cudng them
cac tien
ich
khi do cac dac trung linh kien va tang them do thuan
Igi
cho ngudi
sir
dung.
- Cd the md rgng thiet ke thiet bi thuc hanh bien dieu va ma hoa di thuc hien
di6u
che va ghep kenh doi vdi nhieu ludng PCM vdi cac loai ma dudng khac nhau:
HDB.
Biphase
v.v.
13
PHU LUC 1
DAI HOC
QUOC
GIA
HANOI
Khoa Cong nghe

B6
mon Dien
tir
-
Vi6n
thong
PCS Vu
Nhir Cirong
THONG TIN QUANG
( Giao trinh
dtog
cho sinh vien nam
thii
4 )
Ha noi
2001
PHU LUC 2
CAC BAI
THL/C
TAP
MO TA
HE THONG
Dl-Gidithieu-
H6
thong truyen thong
sgi
quang TTL/EFO la mot cong cu tuyet hao cho phat
tin
hieu s6
TTL.

Hinh
D.
1
m6 ta so do
khdi
cua he thong.
Trong bai thuc tap,
tin
hieu TTL dieu che
cucmg
do anh sang phat
tiir
ngu6n quang
la
m6t
di6t phat quang (LED) phat budc song 820nm. Led
dugc gan
vao mot dau noi ST
d^
ghep
ndi v6i
sgi quang.
Ve
phia
may thu, sgi quang cung dugc noi
vcfi
dau do thong qua
TTL
OUT
TTL

OUT
Hinh
D.
1:
He thdng phat sd TTL
LED source:
ngudn diol
phat quang
TTL in:
Tin
hieu TTL dau vao
Detector: dau do
TTL interface: Chuyen doi TTL
dau ndi ST, dau do quang
chiia
mot
diOt
quang dien pin. Dong dien ra cua dau do quang
dugc khuyech dai
bang
mot bo khuyech dai chuyen tiep cung cap mot dien ap
d Idi
ra.
Sau do la mot bo khuyech dai dai rong va mot mach ngudn
tin
hieu TTL tuong
thich.
De thuc hien kiem tra tren cac mach, khdi mach con
chiia
mot may phat xung thay

doi duoc tan sd.
D2-
May phat-
Cach don gian de
chuyd'n tin
hieu TTL thanh mot xung quang dugc mo ta tren
hmh
D2. Quan sat mach va dac trung " Cong suat
Idi
ra
P^^ydong
mot chieu
Ip " hinh
D3.
Chung ta c6 the suy ra
rSng
khi
tin
hieu TTL
d miic
eao,
dong qua trd
RL
chay qua LED
va phat nang
lugng
quang. Khi
tin
hieu TTL d
miic

thap
thi
dong
I^
bi hap thu bai cua
TTL va dong
Ip
thuc
l6
la
bang
0, khong co
tin
hieu quang
a Idi
ra.
Dong mot
chi£u
cua LED trong trudng hgp nay chuyen
tCr
0 den mot gia tri
cue
dai bi
gidi
han bdi
didn
trd
R^.
No dieu
khiin ht

thdng
tti
vung cat den vung bao hoa cua LED co
tinh
den ca thdi gian tang giam cua cac xung quang gay ra bdi phong dien cua vung
chuyen tiep
(tao
ra cai goi la dien dung chuyen tiep).
Cd
th^
giam dien dung chuyen tiep bang
each
dat
mdt
thien ap len LED de no
luon luon
d
vung hoat dc)ng.
M6t
dong dien tien thien ap dam bao dien dung chuyen tiep khong the
phdng dien qua
miic
can thiet khi LED dong. Cd the giam thdi gian phdng dien bang
each
dieu khien LED vdi cac dinh dong khi chuyen
''
bat-tat" va "tat - bat" dugc tao ra bdi mot
di^n
dung "tang tdc".
Mach dieu khien cho cac he tdc do eao

(tren
vai chuc Mbit/s) can cd tien thien ap
ciia
LED va cua mach "tang tdc".
Chii
y so dd dien
hinh
D.4.
Tin
hieu
TU.
gdm dien ap +5V tuong
ling
vdi sd lieu nhi phan
"1"
va dien ap
= OV
tuong
ling
vdi sd lieu
OV
dugc dat vao cong
NAND
cua mang. Ba
ciia
nay dugc ndi nhu cac cua dao. Cua
thii
nhat lam viec nhu bg dem
each li
con hai cua kia

dugc ndi song song va nhiem vu cua chiing la phat ( hoac hap thu ) mot lugng dong dien
nao dd.
d trang thai ON, dong
Ip^u
qua LED dugc cap bdi ngudn nuoi
(thong
qua cac dien trd
R^
-
va RV2 ) va bdi cac
ciia
TTL qua
R4-R5
va qua
R^
song song
C7.
Bien trd RV2 cho phep
thay doi dong
cue
dai cap cho LED. Trd
R^
song song vdi tu
C^
( dien dung tang tdc )
phat ra cac
dinh
dong de lam tang nhanh thdi gian len xudng cua xung quang. d trang
thai OFF, dong
IQFF

kh^*^
0
va dugc giu d mot gia tri nhd nhat bang mot tut ap tao bdi
dong dien vao tren cac trd
R4,R5
va
R5.
D3-
May thu-
Sa
dd dien tren d
hinh
D.5.
Tin
hieu quang truyen trong sgi dugc phat hien bang
Hinh
D.2
TTL
i
+ 5V
th'L
^
60
50
40
a
30
c
^
20

10
s
//
^c
i
w
///
//
^25
'
\.40
°C
Oc
1.4
1.6 1.6 2.0 2.2 2.4
TheVp-V
CO
c
1.0
o.s
c
0.4
d
< 0.2
g
0
/
/
,/
/

y
-
1
1
-
03
I
&
g
c
0 10 20
30
40 50
60
70
Dong
Ip
-
rnA
s
Hinh
D.3
bd chuyen
ddi
quang
/di^n
la didt quang dien trong bd dau dd HFBR 2406.
Didt quang dien cung cap mdt dong
ti
le vdi

biic
xa anh sang tdi. Bg khuyech dai chuyen
ti6p
cung nam trong dau dd tren cung cap dien ap ra ti le vdi dong vao.
Tin
hieu dien ap
dugc khuyech dai va lam vudng bang 3
cira
ECL lien tiep
(IC3-|j,C 10116
) sau dd dugc
dua vao bg chuyen
ddi
ECL/TTL ( mot cap transitor ) de cho
tin
hieu dang
TTL.
R3
K
•t5V
13
1C2A
741.SCO
12 &
I
J[^IOOM.XS.1M,
C5
C^
R7
56

Cl
R4
39Q
R6
22^
.
RV2
Q
^220Q
R6
4.7Q
Hinh D.4
May phat TTL
D4-
May phat xung
Hinh
D.6 la sa dd mach may phat xung.
TSn
sd cua nd cd
ihi
thay
ddi
trong khoang
IMHz-lOMHz
nhd bien trd
RVl,
tuong
duong vdi mdt md
hinh
sd lieu 0/1 bien

ddi
d
20Mbit/s
+ 5
03
C9
10^
NM-
100 M-
C15
"o.lii
C16
100 M*
R15 IK
R24
TI 2139S6
C19
TOOM
C20
"o.ip.
.T2 213956
iooFrTj::c=i—r
X
-^X AvRl-?
IKA
-OOUT
^OUT
^ R20M MR21
r^R22
r^R23

- 660Qy y560QlJi2odJl20Q
Hinh
D.5 May thu TTL
RVl
Rl
-CZh
lOK 3300
ICIA
l=&
11 10
74HCT14
J_C1
00
p
I"
X^
lci3
^[^^oo^i
"To.iM-
ICIB
14
ICIC
3
14
5
R2
62Q
1
=r
C4

63
p
Hinh
D.6 May phat xung
BAI THUC TAP SO
1
^^ ^
NHAN
BIET
CAC LINH KIEN
• •
Cac thiet bi dugc
sir
dung trong cac bai thuc tap
dugc
mo ta dudi day:
• Kh6'i TTL/EFO
va khoi
DT/EFO
TTUEFO
• •
• • • •
[ > • ]
1
• •
1
:
• •
DT/EFO
O

May do c6ng suat quang
DD
DD
r
71
\
800/1 SOOnm
• Cac nguon quang
cr ciia
s6
thii
nhat va
thii
hai
DD
DD
DD
DD
^ ••
850nm
1 SOOnm
• Cac vong day do thu
200/230
50/125-
10/125
^?r^
4.
• Cac sgi quang
100/130
50/125

-
10/125
1
= 200/220|am
2 =
50/125 urn
3
=
10/125
^m
/
\^
A
/
/
A
A
/
\
A
A
B6 connector
ST-ST
\\\\\\\vm\.
.mwxk
Miliampe
kg",
v6n
M,
dao

d6ng ki
100 MHz
/
^—
/ ^
^\_J
000
/
BAI THUC TAP SO 2
a •
CAC NGUON QUANG
2.1-
Cac
diro^g
dac
trimg
•
Bat
ngu6n cho khdi
•
Thao cau
n6'i Jl
• Thao cau
n6'i
J2, noi miliampe ke vao vi
tri ciia
no
• Noi
vCn
ke qua LED (

giiia
J2 va diem 3 )
• Noi LED vao may do c6ng suat
bing
cac vong day 200/230.
• Thay doi bien
trcf ''thien
ap"
- Do dong
If
qua LED, dien ap
Vp
tren no va
cOng
suat
quang
d
161
ra
P^,,!
ta thu
duae
cac gia tri gio'ng nhu cac gia tri trong bang
Hinh
2.1.
• Ve do thi dong va cac gia tri c5ng suat se thu dugc dudng cong cong suat nguon LED
theo ham
ciia
dong ( Hinh 2.2 )
• Ghi cac gia tri dong va ap len do thi, ta nhan

dugc
dudng bieu
di6n
ddng pilot theo
ham cua ddng thien ap mot chieu ( Hinh 2.3 ).
• Thay vdng sgi quang 200/230
blng
vdng 50/125 hoac 10/125, se thay cong suat do
dugc giam xudng.
IpmA
Vp
mV
p
^
Olll
dBm
58
50
40
30
20
12
1900
1850
1780
1700
1610
1530
-5
-5.5

-6.5
-7.9
-10.2
-12.1
" Pout(d&m)
Hinh
2.1
10 20 30 40 50
Hinh 2.2
Vp(mV)
<—•
xlO'
1.5 1.6 1.7 1.8 1.9
Hinh
2.3
BAI THUC TAP SO
3
• •
MAY PHAT
3.1-
Dong tien thien ap
• Bat dien he thdng
• Ndi cau ndi
Jl
• Thao cau ndi J2 va ndi miliampe ke vao vi
tri
cua no.
• Ndi LED vao dong ho do cong suat
b^ng
sgi quang 200/230

• Ndi
Idi
vao TTL ( diem 2 ) vdi OV. Ddng do dugc
Ij;
khac 0, va cong suat
Idi
ra LED
cung khac 0.
3.2-
Dieu chinh nguon phat
• Bat dien cho he thdng
• Ndi cau ndi Jl
• Thao cau ndi J2 va ndi miliampe ke vao vi
tri
cua no
• Ndi LED vao ddng ho do cong suat
bing
sgi quang 200/230
• Ndi
Idi
vao TTL (diem 2 ) vdi
H-5V.
Ddng
Ip
do dugc phu thuoc su dieu chinh cua
bien trd phan ap va cdng suat ngudn quang cung vay.
3.3-
Cac dang song cua tin hieu truyen di:
• Bat ngudn cho he thdng
• Ndi cau ndi

Jl
vao vi
iri
1
• Ndi cau ndi J2
• Ndi
Idi
ra cua bd tao song TTL (diem 1) vdi
Idi
vao cua bo tao quang(diem 2 ). Dat
t&i
sd bd tao song
d
vi
tri cue
tieu.
• Ndi dao ddng
ki
vao cac
diim
2 va 3. Qua diem 3 cd mot dien ap ti le vdi ddng qua
LED.
Chii
y cac dinh nhd
tuofng
ling mat
trude
song
tin
hieu.

•
Chii
y su tang qua
miic
cua ddng
cue
dai ( do dieu chinh bien trd phan ap ) gay ra su
meo cua dang sdng.
Liic
dd LED d che dd bao hoa va d vung phi tuyen.
BAI THUC TAP SO
4
DAU DO QUANG
4.1-
Trudfc
khi tien hanh kiem tra, ta do nang
luotig
quang ma hai bo tao quang
cung cap:
• Ndi bd tao quang
a ciia
so
thii
nhat vao bo kiem tra quang
b^ng
sgi quang
50/125
ta se
do dugc nang lugng phat ra khoang
15|j.W.

• Sau dd ndi bg tao quang d
ciia
sd
thii
hai: ta se do dugc nang lugng phat ra khoang
13|j.W.
Sd lieu do dugc chi ra
ring
cdng suat ngudn ma bg tao quang d
ciia
sd
thii
nhat
cung cap la hoi
Idn hon
so vdi bo tao quang d cua sd
thii
hai.
• Bat ngudn cho he thdng
• Ndi bd tao quang d cua so
thii
nhat vdi dau dd
bing
sgi quang 50/125. Ndi von ke vdi
diem 4.
• Do dien ap ra cua dau dd,
chii
y la dien ap do dugc ti le vdi ddng didt quang cung cap
• Ndi bg tao quang d ciia sd
thii

hai, do dien ap d diem 4: Thuc te nd bang dien ap do
dugc khi khong cd tfn hieu quang.
• Ngay ca khi cd xet den su khac nhau ve cdng suat quang dua vao hai cua sd
thi vSn
thay didt quang dien cho mot dien ap
eao
han khi budc sdng
ciia
nguon d
ciia
sd thu nhat.
• Ndi lai bd tao quang d
da
sd
thii
nhat. Ndi long
dSn
ghep ndi sgi quang - didt quang
dien di
thdo
didt quang dien ra khoi sgi quang va do dd
gay
ra su suy giam. Ghi lai su
suy giam tuong
ling
cua
diSn
ap do dugc.
BAI THUC TAP SO 5
MAY

THU
5.1-
Phan
tich
dang song
• Bat ngudn cho he thdng
• Ndi cac cau ndi
Jl
va J2
• Ndi
Idi
ra cua bd tao sdng TTL ( diem 1) tdi
Idi
vao cua may phat ( diem 2 ). Dat tan
sd bd tao quangnhd nhat.
• Ndi LED vdi didt quang dien
bang
sgi quang 50/125.
• Ndi dao ddng
ki
vdi cac diem 2,3,4,5,6 va
Ian lugt
xem xet : dang sdng cua
tin
hieu
TIL truyen di, dang sdng cua ddng tuong ling qua LED, dang sdng cua dien ap qua he
"didt quang dien + bd khuyech dai chuyen tiep trd khang";
tin
hieu TTL thuan va dao
5.2-

Sir
bao hoa cua may thu
• Bat ngudn
• Ndi cac
c^u
ndi
Jl
va J2
• Ndi
Idi
ra cua bd tao sdng TTL ( diem 1) tdi Idi vao cua may phat ( diem 2 ). Dat tan
sd bd tao quang nhd nhat.
• Ndi LED vdi dau dd bang 200m sgi quang 200/230.
• Ndi dao ddng
ki
vao cac diem 3 va 4 va do dang sdng
ciia
ddng qua LED va ddng qua
he:
didt quang dien + khuyech dai trd khang chuyen tiep. Neu ddng thien ap cua LED va
do dd keo theo nang lugng phat qua
eao
thi dau dd cd the bi bao hoa va do dd mot dang
sdng vdi bien do bi suy giam nhieu xuat hien d diem 4. De ngan
ngira
hien tugng nay,
dieu chinh nhe thien ap ( bien trd thien ap ) hoac thao nhe sgi quang khdi dau dd hoac
LED.
Chii
y la khi bg dau dd gan bao hoa, cac xung nhan dugc dan ra nhieu. Dd la do

thdi gian dap
ling
cua may thu tang khi nang lugng quang tang.