Đồ Án tốt nghiệp 2014
TRANSCRIPT
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LI NI U
Trong x hi thng tin v truyn thng hin nay, cng vi spht trinmnh mca cc ngnh cng nghkhc v sbng nvkinh t l sphttrin khng ngng ca cng nghvin thng.Kthut vin thng hin nay ng
dng hu ht cc kt qunghin cu tch cc trc trong lnh vc vin thngv ngy cng hon thin hn, n gn nh ng dng hu ht cc c sl thuyt vthng tin s. Sha v truyn dn tn hiu dng sl mt phng php tng hiuqutruyn dn v gim thiu sai st thng tin do tc ng ca nhiu so vi thngtin tng t, ng thi ph hp vi cc hthng xl ngy nay ly c stc v hiu sut lm nn tng nn cc dliu dng sc sdng.
Trong cc phng php iu chschng ta phi nhc n phng phpiu chkha dch bin(ASK: Amplitude shift keying), n l mt phng phpc bn nht v n gin nht tin hnh iu chmt tn hiu. N l nn tngtrc tin cn nghin cu c thnghin cu thm cc hthng khc cao hn.ti l mt vn c trong vin thng c nhm ng dng vo vic truyn dliu thoi. ti nghin cu ng dng kthut ASK truyn dliu thoi.
Tnh hnh nghin cu trong v ngoi nc:Hin nay cng nghvin thng thgii t n mt trnh cao vi vickhng nhng truyn nhn tn hiu thoi m ngi ta c thtruyn cc tn hiu hnhnh, phim nh cng nh bt kmt dliu no m ngi ta c thsha vi tc
cc cao ln ti hng Mhz vi cng nghdi ng v ln ti hng Ghz nh cchthng truyn dn chnh nh viba s.Vic iu chtn hiu truyn i trong khng gian khng chn thun l iuchbin cxa m l cc hthng phc tp kt hp ciu chtn s, pha v
bin t c hiu qucao nht.Tuy nhin u l thnh qunghin cu ca cc nc pht trin, cn vi Vit
Nam cng nghdi ng vn chdng mc ng dng chcha t ti trnh cthnghin cu to ra mt cch thc, mt l thuyt mi hay xy dng mt hthngthng tin.
Do vy, vic nghin cu cc cch thc iu chc bn cng nhm lm tincho vic nghin cu tm hiu cc hthng phc tp hn, ng thi cng lcch ngi nghin cu c thny sinh t nhng tng mi.
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Trang ii
LI CM N
Nhm thc hin ti xin gi n ton thqu thy c trng i Hc SPhm KThut Tp.HCM ni chung v qu thy c khoa in - in tni ring
li cm n chn thnh nht. Qu thy c truyn t cho nhm nhng kin thcchuyn ngnh cng nh nhiu kinh nghim qu bu l nhng hnh trang rt cnthit cho nhm bc ra trng v cng tc sau ny sau gn 5 nm gn b vitrng.
c bit nhm xin gi li cm n su sc n TS. V Minh Hun hngdn cho nhm rt tn tnh trong sut thi gian qua cng nhng li ng vin,khch lgip nhm vt qua thi im kh khn.Nhng ti liu bch cngnhng li gp qu bu gip nhm hon thnh n ny.
Cm n tt cbn b, nhng ngi ng gp kin v lun ng vin
gip nhm hon thnh n ny.Xin chn thnh cm n.
Nhm sinh vin thc hin
Trn Hi Sn Trn Nguyn Tr
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MC LC
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LIT K HNH
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LIT K TVIT TT
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TM TT
Ni dung nghin cu:nghin cu cch thc truyn tn hiu v tuyn, nhm tin hnh nghin
cu struyn nhn tn hiu thoi vi hnh thc iu chn gin nht l iu ch
bin ASK. Nghin cu cch thc mt tn hiu ting ni c iu chv truyni trong khng gian, t gii iu chkhi phc li tn hiu ting ni truyn i v a ra loa.
ng thi vi vic nghin cu xy dng hthng truyn nhn trn, mcch ca vic nghin cu cng nhm kim chng cc c sl thuyt viu ch,m ha, thu pht, khuch i tn hiu t pht trin cc hthng tt hn vsau nu c c hi.
Cng vi cc mc ch nghin cu tm hiu kin thc l vic nhm thchin cng trnh nghin cu rn luyn knng nghin cu khoa hc, tch gpkinh nghim cho bn thn.Phng php nghin cu:
nghin cu mt vn khoa hc lun c nhng con ng khc nhautip cn vn . C thtin hnh nghin cu tchi tit n tng thnhcccng trnh nghin cu to ra sn phm thi cng, hoc cng c thtin hnh nghincu i tci tng quan n tng chim ring nh vi cc cng trnh nghin cul thuyt.
y, xy dng mch hon chnh, nhm tin hnh nghin cu hot
ng tng khi mt, kim tra vi tng khi ring lthy c hot ng cami khi, t kt hp cc khi v iu chnh ph hp xy dng nn mch snphm, tc l i tci chi tit n ci tng th. Lm nh vy chng ta c thddng kim hot ng ca mi khi v ddng khc phc nu xut hin li
Cthqu trnh nghin cu:
Giai on u nhm tp trung nghin cu hon thnh cc mch c bn c bit trong qu trnh thc tp c tnh cht n gin dthc hin.
Tip theo nhm tin hnh nghin cu thc hin vic iu chv gii iuchASK vi tn hiu mu ly tbto xung vung.
Sau khi kim tra chy n nh vic iu chASK, nhm tin hnh nghincu vic m ha v gii m PCM sdng IC TP3057.
Cui cng nhm tin hnh nghin cu v xy dng hthng thu pht tnhiu iu chqua Anten.
Giai on cui cng l hon thin mch v vit bo co khoa hc.
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Trang vii
ABSTRACT
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CHNG 1: GII THIU
CHNG 1: GII THIU
Nh gii thiu trn, cng nghnghin cu khoa hc ca nhm i vo nghincu xy dng mt hthng truyn nhn tn hiu da vo phng php iu chbin
ASK. Trc ht l thc hin iu ch, truyn v gii iu chmt tn hiu tto, tiptheo si tin hnh iu chtn hiu thoi (tn hiu ging ni) truyn i, cui cngl sthc hin truyn v v tuyn (khng dy).
Sau y chng ta stin hnh i tm hiu s lc viu chASK v vic truyntn hiu thng qua iu chASK v qu trnh thi cng mch.
1.1.S lc iu chASK:ASK (Ampitude Shift Keying) iu chkho dch bin : sng iu bin c
to ra bng cch thay i bin sng mang theo bin tn hiu tin tc
1.1.1. Nguyn l iu ch:Dng cc bit 0 v 1 thay i bin ca sng mang.
Sdng mt tn ssng mang duy nht.
Hnh 1.1:Nguyn l iu ch
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CHNG 1: GII THIU
Hnh 1.2: Dng sng
1.1.2. Biu thc ton hc:Tn hiu sng mang:
Vc(t) = cost (1.1)
Tn hiu tin tc:
Vd (t) =
(1.2)
Tn hiu sau khi qua biu chASK:
VASK (t) = Vc (t).Vd(t)
=
(1.3)
Ta c: 2cosa.cosb = cos (a + b) + cos (a - b)
VASK (t) =
{( ) (
) [( ) ( )] } (1.4)
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CHNG 1: GII THIU
1.2.Gii iu ch:C 2 phng php:
+Kt hp: mch phc tp nhng c khnng chng nhiu tt.
+Khng kt hp: mch n gin thng sdng trong mch tch sng hnhbao.
Hnh 1.3: S v dng song gii iu chASK
1.3.u im v nhc im: u im:+ n gin: Dng 2 bin khc nhau ca sng mang biu din 0 v 1,
sdng mt tn ssng mang duy nht.
+ Phng php ny chph hp trong truyn dliu tc thp ( 1200bpstrn knh truyn thoi )
Nhc im:+ Dbnh hng bi nhiu.
+ Khng ph hp i vi cc tn hiu c truyn trong cc knh truynyu cu tc cao.
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CHNG 1: GII THIU
1.4.S khi truyn nhn tn hiu sdng iu chASK:
Hnh 1.4: S khi
Nguyn l:
+iu ch:
Tn hiu tin tc trc khi iu chc a qua blc thng thp loibcc nhiu tn scao.Sau tn hiu c iu chbin vi mt sng mangnhmt bnhn.Tn hiu sau khi iu chc cho qua mt blc thng di ly di thng ca ca tn hiu cn truyn i,tit kim bng thng.
+Gii iu ch:
Tn hiu iu chASK c a qua bnhn tch ly tn hiu cn thuv loi btn hiu sng mang. Sau tn hiu c cho qua blc thng thp
loi bton bthnh phn nhiu tn scao.
BPF
PSTNLPF
VASK(t)
Vd(t)Vd(t)(tin
tc)
Vc(t)
(sng mang)
Vc(t)
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CHNG 2: HTHNG THU PHT TN HIU
CHNG 2: HTHNG THU PHT TN HIU
2.1. S khi ca hthng :2.1.1. S khi pht:
Hnh 2.1: S khi pht
2.1.2. S khi thu:
Hnh 2.2: S khi thu
Khi nhn
tn hiu t
MIC
Khi iu
chPCM
Khi khuch
i cao tn
Khi iu
chASK
Khi to d
liu s
Khi to
dao ng
anten
Khi thu
anten
Khi khuch
i trung
tn
Khi gii
iu ch
ASK
Khi khuch
i m tn
Khi gii m
PCMloa
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CHNG 2: HTHNG THU PHT TN HIU
2.2. Thit kv xy dng mch in:m bo vic test mch c ddng nhm lm tng khi ring l
v sau khi hon thnh nhm sghp chng trn cng mt board mch.
2.2.1. Khi to dliu s:Khi ny c chc nng to dliu tn hiu iu chdng sd
dng cho vic kim tra cc khi pha sau trc khi thc hin iu ch tnhiu thoi truyn i.
Khi ssdng ngun dao ng tbdao ng bn bpht a
vo lm ngun xung tn hiu, sau tn hiu sa qua cc thanh ghi dch(IC 7495), tin hnh dch dliu nhcc Switch a ra dng dliu
smong mun.Dliu y l dng s8 bit vi cc bit c ththay i gitrl 0 hoc 1 ty thuc vo Switch.
Khi ny c thit kgm c 8 led n m tgi trbit tngng vi mi Switch, led sng tng ng vi bit c mc logic l 1 v
ngc li.
Mch dliu 8 bit sdng 2 IC dch 7495 mc ni tip to ra dliu 8 bit, vi d liu ng vo song song, d liu ng ra ni tip. D liu
ng vo c xc nh bng cch thay i cc switch tSW1 n SW8. IC7414 cng vi R, C to ra mch dao ng cung cp xung clock cho IC 7493
(IC m nhphn) m, 4 ng ra ca IC ny c ni n IC 7421 (IC cngAND), khi IC 7493 m 16 xung, ng ra ca cng AND ln 1, tc ng
ln chn s6 (chn mode) ca IC 7495, chn ny mc 1 sload dliu ng vo, nu mc 0 n sdch dliu. Ng ra QA ca IC 7493 c ni
n chn 8 v 9 (2 xung clock dch dliu ca IC 7495), khi chn s6 mc 0 th 2 xung clock ny tc ng dch dliu ra v dliu sny ldliu NRZ n cc, n sc ly ti NRZ data.
IC 7421: l IC gm 2 cng And 4 ng vo cu to nh hnh
di:
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CHNG 2: HTHNG THU PHT TN HIU
Hnh 2.3: S chn ca IC 7421
IC 7493: chc nng m thp, nhphn
Cu to n gin gm cc Flip Flop JK bntrong mc nh JK c ni mc cao do FFch c th hot ng trng thi lt. Trongmodul NRZ ny IC c thm c th chn12 ni chn 1 m nhphn 16 trng thi. Hnhdi sr hn
Bng 2.1: S chn v chc nng ca IC 7493
Hnh 2.4: S mch in bn trong IC 7493
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CHNG 2: HTHNG THU PHT TN HIU
Bng 2.2: Bng trng thi IC 7493
IC7495:y l thanh ghi 4 bit,IC c 3 chhot ng:
Ti song song. Dch phi khi cp xung (High to Low) vo chn 9 ng
thi chn 6 (Mode Control) mc thp.
Dch tri khi cp xung clock vo chn 8 ng thi ngthi chn 6 mc cao.
Pin 1:SER l chn dliu ng vo ni tipPin 2,3,4,5:l 4 ng data vo D1D4 tng ng vi ccPin 13,12,11,10: l dliu ng ra song song QAQDPin 6:Mode chn chPin 8, 9:2 chn cp xung clockPin 7:GND ni massPin 14:VCC ni ngun
Bng 2.3: S chn 7495
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CHNG 2: HTHNG THU PHT TN HIU
Bng 2.4: Bng trng thi ca IC 7495
Hnh 2.5:S mch in bn trong IC 7495
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CHNG 2: HTHNG THU PHT TN HIU
S nguyn l ca mch:
Hnh 2.6: S nguyn l khi to dliu s
Cc in trhn dng c gi trt330 - 1K, tng ng vi ngun VCCl
+5V, m bo cho led sng tt v khng bchy.
2.2.2. Khi nhn tn hiu tMIC:Sdng Transistor BJT, kt hp vi 1 Opamp khuch i bin
v iu chnh bin tn hiu nu cn.
Mch khuch i BJT c mc dng cu phn p vi cc E chung,ng ra tn hiu sc khuch i vdng v p
Opamp khuch i khng o,h s khuch i c th c iu
chnh nhbin tr10K,c gi trbin i t1 n 10 ln ty thuc vo gitrca bin tr.
Snguyn l ca mch:
U174LS95
SDI
1
A
2
B
3
C
4
D
5
MODE
6
CLK1
9
CLK2
8
QA
13
QB
12
QC
11
QD
10
U2
74LS95
SDI
1
A
2
B
3
C
4
D
5
MODE
6
CLK1
9
CLK2
8
QA
13
QB
12
QC
11
QD
10
D1
LED
D2
LED
D3
LED
D4
LED
J3
CON2
12 U4A
74HC21
14
52
6
D5
LED
D6
LED
D7
LED
D8
LED
MODE
VCC
BK
R1R
R2R
R3R
BK
R4R
R5R
R6R
R7R
R8R
CLK IN
U3
74LS93
CLKA14
CLKB
1 QA
12
QB
9
QC 8
QD 11
R012
R023
J1
NGUON
12
J2
WORD_8BIT
12
MODE
SW1
SW
SW2
SW
MODE
SW3
SW
SW4
SW
SW5
SW
SW6
SW
SW7
SW
SW8
SW
NRZ OUT
VCC
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CHNG 2: HTHNG THU PHT TN HIU
Hnh 2.7: S nguyn l khi nhn tn hiu tMIC
2.2.3. Khi m ha PCM:C nhiu gii php thc hin vic m ha PCM nh l:
- Thc hin m ha da trn cc IC sthng dng vi cc chc nng
c chia nhnh l ly mu, lng tv m ha, t gom li thnh mththng iu chPCM. Phng php ny dhiu v dthc hin, ddng
cho vic phn tch mch.Tuy nhin mch kh thi cng, phc tp tn nhiuIC, dbli v hot ng khng chnh xc nu thi cng khng ng.
- Phng php th 2 l s dng VK d thc hin cng vic mha. Phng php ny sn gin nu vic lp trnh tt, vic ng btnhiu cng tt hn do chly tmt ngun xung Thch anh duy nht. Tuynhin yu im ca phng php ny l VDK ch x l c tn hiu sdng nhphn m tn hiu thoi l tn hiu tng tnn ta khng thtrc
Q1BC 548B
C1
0.1u DC
C210uF 16V
C3
1uF 16V
R12k7
R2100k
R31k5
R433k
R5
470E
VCC 15V
J2THAY CON2 = BUS 2 CHAN
1
2
R6 POT
10K
-
+
U1
OP-07
3
26
7 1
4 8
R71K
VCC 15V
VCC -15V
J3
VCC 15V
123
VCC 15V
VCC -15V
IN
IN
U2
MICRO 3ly
GND1
LINE1
2
LINE2
3
U3
MICRO 6ly
GND
1
LINE-L
2
LINE-R
3
GND
4
LINE-L
5
LINE-R
6
IN
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CHNG 2: HTHNG THU PHT TN HIU
tip xl trn tn hiu thoi m phi qua khu chuyn i tn hiu tanalogsang digital trc khi m ha v thc hin qu trnh ngc li khi gii m.T ncng sto ra sai strong qu trnh chuyn i dliu dn nlm sai khc tn hiu gc.
- Phng php th3 l sdng IC TP3057/ TP3054 vi chc nng
c th l thc hin m ha PCM. Vi tn hiu u vo l tn hiu cn mha dng analog v d liu u ra l tn hiu c m ha PCM dng s. IC ny c th cho vic iu chdliu sdng trong truyn tnhiu thoi, rt tin dng. IC TP3057 c sn xut theo chun ca Bc M,
s dng xung clock lung 2,048Mhz m ha. Cn IC TP3054 th snxut theo chun ca Ty u, sdng xung clock lung 1,544Mhz mha.
Nhm nghin cu chn gii php sdng IC c th TP3057 thc hinm ha v gii m PCM.
S nguyn l mch:
Hnh 2.8: S nguyn l khi PCM
U1
TP3057
AGND2
DR6
DX11
-VCC1
+VCC4
VFRO3 GSX
14
TSX13
VFXI+ 16
VFXI-15
FSR5
BCLKR/CLKSEL7
MCLKR/PDN8
MCLKX9
BCLKX10
FSX12
C10.1uF
C20.1uF
+5V
-5V
+5V
R1 10k R2 10k
BCL 64KHZ
8KHZ
IN_ANALOG
OUT_PCM
MCL 2048MHZ
IN_ANALOG
OUT_PCM
BCL 64KHZ8KHZ
MCL 2048MHZ
J1
OUT PCM
1
J2
IN ANALOG
1
J3
HEADER 3
1
23
J4
VCC 5V
12
3
+5V
-5V
KHOI PCM SU DUNG TP3057
J5
MASS
1
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CHNG 2: HTHNG THU PHT TN HIU
Cc tC1 v C2 lm nhim vlc ngun cho IC
- Cc trR1 v R2 l trto hskhuch i cho bkhuch i uvo ca IC TP3057.
- Tn hiu analog cn iu cha vo chn 16.
- Tn hiu sPCM ra chn 11.
- Chn s9 l chn cp xung clock master cho IC hot ng.
- Cc chn FSX v FSR l chn nhn xung ng bkhung cho vicm ha v gii m.
- Chn VFRO l chn dliu analog ng ra khi thc hin gii m
PCM.- Chn DR l chn dliu PCM ng vo cn gii m khi phc
tn hiu gc.
- Chn s7 BCLKR/CLKSEL c chc nng nh bng sau:
TABLE Selection of Master Clock Frequencies
BCLKR/CLKSEL
Master Clock
Frequency Selected
TP3057 TP3054
Clocked 2,048Mhz1,536Mhz
or1,544Mhz
01,536Mhz
or1,544Mhz
2,048Mhz
1 2,048Mhz1,536Mhz
or
1,544Mhz
Bng 2.5: La chn tn s
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CHNG 2: HTHNG THU PHT TN HIU
- Chn s8 l chn nhn xung master clock cho vic gii iu chkhi tn hiu vo chn ny l xung, nu c c kt ni ln mc "1"lin tc th power down thit b, khi kt ni lin tc ln mc xungmc "0" th n sly xung master clock bn pht lm master
clock cho bn nhn.
Mt IC TP3057 c thng thi thc hin cng vic m ha v giim PCM bi v hai khi ny c thit kring ltrong cng mtIC, khng nh hng g n nhau.
2.2.4. Khi to dao ng:to ra ngun dao ng n nh cung cp cho cc khi trong h
thng, nhm thc hin chn phng n dng mch dao ng Thch anh.
Tinh ththch anh to ra dao ng vi n nh cao v t bnh hngbi yu tbn ngoi.
Mch dao ng gm mt tinh ththch anh 4Mhz kt hp vi cccng o v cc t, in trto ra xung clock cnh c tn s4Mhz.
Ngun xung clock ny sc cho qua IC chia tn CD4040 m ly cctn sng ra mong mun.
Ng ra chn s9 l xung clock tn s2,048Mhz lm xung master
clock cho PCM, cc ng ra chn s2 (64Khz) l xung bit clock v chn s12 (8Khz) l xung FSX cung cp cho PCM.
Ng ra chn s6 l xung tn s512Khz sc a n mch lcPI to ra dng sng sin lm sng mang iu chcho mch iu ch
ASK.
Mch lc PI gm 2 loi linh kin thng l tv cun cm nhmhiu chnh xung vung thnh dng sng sin ddng cho vic iu ch
ASK.
S nguyn l mch:
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CHNG 2: HTHNG THU PHT TN HIU
Hnh 2.9: S nguyn l khi to dao ng
2.2.5. Khi iu chASK:iu chASK l nhm bin i bin ca tn hiu sng mang theo
dng ca tn hiu tin tc. iu m ta mong mun chnh l truyn tn hiu tintc i xa (c dy hoc khng dy). Tuy nhin vi cc tn hiu nm dy
tn sm thanh (tn hiu thoi) th c tn sthp (300Hz - 3,4Khz) cho nnkhng ththc hin vic truyn i xa v tn hiu sbnh hng bi v s
cc loi nhiu cng tp m. Do vy chng ta cn phi nhn mt sng ctn scao vt ra khi di tn sm thanh mang tin tc i. Vic ghp
tn hiu sng mang v tin tc c gi l iu ch. C nhiu loi iu ch
khc nhau nh iu chbin , iu chtn s, iu pha, Tuy nhin y ta chxt phng php iu chn gin v dthc hin nht l iu
bin.
C nhiu cch iu chbin khc nhau nh sdng transistor, sdng IC chuyn dng. y, ddng thc hin v m bo n nh,
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CHNG 2: HTHNG THU PHT TN HIU
nhm nghin cu chn gii php sdng IC iu chchuyn dng lIC1496.
S chn IC1496
Hnh 2.10: S chn ca IC 1496o Chn 1, 4: tn hiu ng vo tin tc.o Chn 2, 3: hiu chnh khuch i.o Chn 5: Bias.o Chn 6, 12: ng ra.o Chn 8, 10: ng vo sng mang.
Hnh 2.11: S khi MC1496
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CHNG 2: HTHNG THU PHT TN HIU
S nguyn l mch:
Hnh 2.12: S khi iu chASK
Mch bao gm mt bkhuch i vi sai 4 transistor trn da trnbkhuch i vi sai tiu chun vi ngun dng i. Cc thu ng ra c
ghp cho m dng sng y c cn bng khi php nhn ca 2 tnhiu in p xy ra. l tn hiu ng ra l mt thi hng ca php nhn 2tn hiu ng vo.
Cc transistor v in tr, tin mc thm bn ngoi l nhm
iu chnh dng sng iu chcng nh hsiu ch.
IC 1496 c dng nh l biu chcn bng. Tn hiu NRZiu chth c kt ni ti chn 1 qua transistor m BC548B.
IC ny c hai ng ra lm vic nh biu chcn bng. Ng rathhai c thc kt ni vi chn 4 qua transistor m BC548B.
DIEU CHE CAN BANG
R11
1K
R12
10K
+5V
-5V
R13470
R14
330K
R154K7
R16
470
R1710K
C20.47uF
C3101
+15V R18
2K
OUTPUT
R19
470
R20
4K7
R21
470
R22470
R232K2
R241K
-15V
J8
DATA_IN
12
DATA
J9
CARRIER_IN
12
DATA
CARRIER
J10
VCC 5V
123
+5V
-5V
CARRIER
U1
MC1496
CIN+8
CIN-10
SIGIN+1
SIGIN-4
GADJ
2
GADJ
3
OUT+ 6
OUT- 12
VEE
14
BIAS
5
Q1
BC548
Q2
BC548
Q3
BC548Q4
BC548
Q5
BC558
Q6
BC558
R1
10KR2
5K1
R3
1K
R4
6K8
R5
10K
R6
10K
R75K1
R8470
R9470
R10
1K
R2810K
+15V
+15V
+15V
-15V
+15V
C1
0.47uF
J3
VCC15v
12
J4
OUTPUT
12
-15V
+15V
OUTPUT
-15V
-15V
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CHNG 2: HTHNG THU PHT TN HIU
Tn hiu sng mang m tn th c kt ni ti chn 8 qua tghp tbdao ng sng mang m tn.
Nhng ng ra c iu chc c chn 12 v 6 ca IC ny,sau c khuch i cn bng bi cp transistor BC548B v BC
558B.Ng ra iu chcn bng cui cng c xc nh ti ng ra.
Bin tr10K c sng mang cn bng trong khi bin tr1 K thc tn hiu m tn ng vo cn bng.
t trc ng ra 100K iu chnh mc 0 DC ng ra. Bin trng ra 2K thay i mc (bc) ca tn hiu iu chASK.
-5 n +5V DC c xc nh bi ng ra th2 ca biu chcn bng a vo sng mang ng ra ASK.
2.2.6. Khi khuch i cao tn:Tn hiu sau khi iu chc tn sca sng mang c thtruyn
c trn knh truyn khng dy. Tuy nhin cng tn hiu th cha v n sbsuy hao gn nh hon ton nu nh khong cch xa v vic khi
phc l srt kh khn. Do vy, ta phi tin hnh khuch i cng sut pht
i tn hiu pht i c cng sut ln truyn i xa v bn nhn c ththu v gii iu chtn hiu .
Bkhuch i n gin l dng transistor khuch i cng sut. Phichn loi p ng tt tn scao v cng sut ln.
Cc transistor mc dng phn cc, c 2 tng khuch i: mt tngmc dng C chung khuch i dng, mt tng mc dng E chung khuchi cdng v p.
Tn hiu sau khuch i ln b trsuy hao qua knh truyn.
S nguyn l mch:
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CHNG 2: HTHNG THU PHT TN HIU
Hnh 2.13: S khi mch khuch i cao tn
2.2.7. Khi thu, khi khuch i cao tn v khuch i trung tn:Mch vo anten bao gm cc linh kin thng l in cm v t
in hot ng trn nguyn tc mch cng hng tn s, mch vo sto ra
tn sdao ng ni chnh l tn sca tn hiu pht. Khi , u vo b
thu, tn hiu pht c cng tn svi tn sdao ng ni sc thu vo.Trn y l dng gin lc ca mch thu i tn, tn spht l cnh nnmch thu sdng tn scnh cho n gin.
Mch tin khuch i: L khuch i thu c, bi v tn hiu thu
c c cng rt thp, khng tha i gii iu chc. V vy, tastin hnh khuch i mc tn hiu ln mt mc ng k.
Mch khuch i trung tn: Tip tc khuch i tn hiu thu c v
iu chnh li ca mch. Vi mt smch ta c thsdng nhiu lpkhuch i trung tn khuch i tn hiu, nhng y, ta thc hintruyn nhn gn nn chcn sdng mt tng khuch i khuch i tn
hiu trc khi a i gii iu ch.
J4
CON1
1
R34
5K6
R35
1K
An
ten
KHOI KHUECH DAI CONG SUAT+15V
J1
Power
12
+15V
C410n DC
C5
0.1 DC
C6
0.1 DC C7
0.1 DC
R26
10k
R27
4k7
R28
100E
R29
100K
R30
18K
R31
100E
R32
100E
Q11BC547
Q12BC547
R33
10k
J2
CON2
12
IP
IP
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CHNG 2: HTHNG THU PHT TN HIU
S nguyn l mch:
Hnh 2.14: S khi mch thu
2.2.8. Khi gii iu chASK:Vic gii iu chy sdng mch tch sng hnh bao sdng
Diode, kt hp tv diode thc hin lc btn hiu sng mang tn scao,gili dng bin ca tn hiu chnh l tn hiu tin tc cn ly.
Sau khi lc ly tn hiu tn sthp th ta stin hnh a tn hiu qua mch quyt nh ly li dng sng vung ca tn hiu PCM.
Sng vung ny chnh l tn hiu tin tc c m ha PCM.Tn hiu ny sc a n mch gii m PCM khi phc tn
hiu tin tc gc (tn hiu thoi)
S nguyn l ca mch:
U1
Bien_ap_doi
11
22
3 3
4 4
J1Antenna
1
CghCAP NP
VC
CAP NPR1390K
R3
150E
R41K
Q1ABC548
1
3
2
+5V
J3
VCC 5V
12
C1
103
Q2A
1
3
2
U2
Loi_trung_tan
A11
A22
A33
B1 4
B2 5
R2100E
+5V
C24,47n
C5C182n7 st
C647n
J2
OUT TO DEMOD
1
MACH VAO ANTEN MACH
KHUECH
DAI TRUNG
TAN
MACH TIEN
KHUECH DAI
+5V
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CHNG 2: HTHNG THU PHT TN HIU
Hnh 2.15: S khi gii iu chASK
2.2.9. Khi gii m PCM:Chn gin sdng cc chn ng ra ca phn gii m PCM ca IC
TP3057.
S mch cng tng tbn mch m ha.
S khi ca mch:
D1
4148C1102
R110k
R210K
U1
LM311
IN +2
IN -3
GND
1
VCC
-
4
B
5
O/B
6
OUT7
VCC
+
8
J1
IN
1
2
J2
OUT
1
2
R32K2
R4
10K
U2A
7404
1 2
VCC +15V
VCC +15V
VCC -15V
VCC -15V
VCC
J3
VCC5V
12
VCC
J5
VCC 15V
12
VCC +15V
VCC -15V
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CHNG 2: HTHNG THU PHT TN HIU
Hnh 2.16: S khi mch gii m PCM
2.2.10.Mch khuch i cng sut m tn:Mch khuch i tn hiu m tn sdng IC TDA2003, khuch i
cng sut ca tn hiu thoi a ra loa.
Mch ng dng ny ly tdatasheet do nh sn xut cung cp.
Mch c thkhuch i cng sut n 6W.
S khi ca mch:
U1
TP3057
AGND2
DR6
DX 11
-VCC1
+VCC4
VFRO3 GSX
14
TSX 13
VFXI+ 16
VFXI- 15
FSR5
BCLKR/CLKSEL7
MCLKR/PDN8
MCLKX 9
BCLKX 10
FSX 12
C10.1uF
C20.1uF
+5V
-5V
R1 10k R2 10k
BCL 64KHZ
8KHZ
OUT_ANALOG
MCL 2048MHZ
IN_PCM
OUT_AN
ALOG
BCL 64KHZ8KHZ
MCL 2048MHZ
J1
OUT PCM
1
J2
IN ANALOG
1
J3
HEADER 3
1
23
J4
VCC 5V
12
3
+5V
-5V
KHOI PCM SU DUNG TP3057
J5
MASS
1
IN_PCM
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CHNG 2: HTHNG THU PHT TN HIU
Hnh 2.17: S khi mch khuch i cng sut m tn
U3
TDA2003
IN+1
IN-2
GND
3
OUT 4V
CC
5C1
10uF
C2100uF
C3
470uF
C4
1000uF
C5100nF
C6100nF
Cx1/2piBR1 = 39nF
R1220E
R22R2
R31
RX20xR2 = 39E
J1
THAY CON2 = BUS 2 CHAN
1
2
J2
1
2
VCC 12v
J3
12
3
J4
VCC 12V
12
VCC 12v
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
CHNG 3: GII THIU PHN MM VMCH V M PHNGPROTEUS
3.1. Gii thiu phn mm:Proteus l phn mm htrthit kv m phng cc loi mch in t. So
vi cc phn mm htrm phng cc mch in khc nh:
Circuitmaker 2000 ngoi vic htrthit kmch in th phn mmcn cho php vv m phng mch schun xc ti 95% nhng li
bhn chkhi m phng cc loi mch tng tcng nh tng hpcsv tng t.
Workbench phn mm ny c th linh kin phong ph v c nhiuthit bo kim tra nh thc tgip ngi thit kddng quan stcn chnh thng sca mch in. So vi cc phn mm khc th
Workbench cho php m phng cc loi mch in (csv tngt).
Orcad, Eagle v Protel l cc phn mm htrv vs nguynl v s mch in nhng khng htrm phng mch nguyn l.
Proteus c thmnh hn hn vcc mt:
Th vin linh kin phong ph. Htrnhiu thit bo kim tra. Cho php thit kv chy m phng s nguyn l gm cc mch
tng t, mch s, mch tng hp csv tng t Cho php chy m phng cc loi vi iu khin, EPPROM, PIC Htrthit kmch in.
3.2. Hng dn sdng phn mm Proteus:3.2.1. Khi ng chng trnh:
Sau khi ci t Proteus, vo Start menu, khi ng isis ca Proteus:
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
Hnh 3.1 Vo giao din mProteus
3.2.2. Giao din chnh:
Hnh 3.2: Giao din chnh
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
3.2.3. Cc toolbar chnh:Thanh s1:
-Cm 1: to nhanh mt trang thit k, m trang thit k to,lu trangthit k
-Cm 2: In ctrang,chn vng ib ty -Cm 3: Chia li im trang thit k.-Cm 4: Zoom linh kin v gia trang,phng to,thu nh, fix trang,zoom
vng tuchn.-Cm 5: Ct, coppy, paste trang.-Cm 6: Copy, move, quay, xo linh kin trn trang.
-Cm 7: Chvng biu tng u,chn linh kin.
Thanh s2:
1. Cho php chn linh kin sau khi nhn nt P hp thoi DEVICES.2. Chm im trn trang.
3. To nhn:nhn tri chut ln dy dn v t tn.4. Text: nhn tri chut v v.5. To Bus6. Khng sdng7. Nhn tri ln linh kin xem edit component.8. Ngun, t, bus9. Chn linh kin.10. Simulation Graph.11. Tape recorder.
12. Generator: DC, xung, sin, 13. Voltage Probe: ging vn kthng nhng chc mt u dy, hin strc tip.14. Current Probe: ging ampe knhng chc mt u.15. Dng co: oscilloscope.vn kAC, DC, ampe kAC, DC16. Vng 2D.
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
17. Vhp 2D.18. Vng trn 2D19. Vcung trn 2D20. Va gic 2D
21. Text 2D: nhn tri vo trang va type.
Thanh s3:
Quay tri, phi, i xng chn ngang dc linh kin trnhp hin thlinh kin.
Thanh s4:
iu khin Start, step by step, pause, stop qu trnhm phng.
3.2.4. Thit kmch m phng:
Hnh 3.3: Mch m phngu tin ta ly tt c cc linh kin cn dng ra hp thoi
DEVICES bng cch nhn vo chP hp thoi DEVICES, ta schp thoi Pick Devices hin ra nh sau:
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
Hnh 3.4: Giao din hp thoi Pick Devices
G tn linh kin cn ly vo Keywords.
Hnh 3.5: Giao din Keywords
Hnh linh kin v s chn mch in shin ra bn cch khi ta nhnvo chn linh kin. chn ta nhn OK lc ny trn hp thoi DEVICES
sxut hin tn linh kin chn.
ly linh kin cn thit k ta nhn vo tn linh kin trong hp
thoi DEVICES, dng thanh cng c thay i cho phhp sau sang nhn tri vo trang thit kt linh kin.
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
Ta ln lt a cc linh kin cn dng ra trang thit k. Ngun v
t ly ra bng cch nhn vo biu tng trn thanh cng cs2, ta spxp cc linh kin theo mch nguyn l.
i dy ta nhn vo chn linh kin thnht, di chuyn chut vnhn vo chn linh kin th2. sa mt linh kin ta nhn p chut lnlinh kin .
Nh vy ta m phng xong mch hon chnh. chy mch tanhn vo nt Start trn thanh cng cs4.
3.2.5. Kt qum phng c ca mt smch trn Proteus:3.2.5.1. Mch m phng khuch i cng sut m tn:
Hnh 3.6: M phng mch khuch i cng sut m tn
trn Proteus
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
Hnh 3.7: Dng sng tn hiu ng vo v ng ra ca
mch khuch i cng sut m tn
Tn hiu ng vo c bin 1V v tn s1Hz.
Tn hiu ng ra c khuch i ln v c bin l 5V gp 5 ln so vi
bin ca tn hiu ng vo.
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
3.2.5.2. M phng khi thu:
Hnh 3.8: M phng khi thu trn Proteus
Hnh 3.9: Dng sng ca tn hiu ng vo v ng ra ca
mch thu
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
Nhbthu thu c tn hiu iu chASK c khuch i avo bgii iu chkhi phc li tn hiu ban u.
3.2.5.3. M phng mch iu chASK:Do qu trnh m phng ASK trn Proteus gp kh khn nnnhm tin hnh m phng ASK trn Matlab phn mm m
phng mch c hc trong chng trnh o to khi vinthng.
Tn hiu tin tc c biu thc:
[() ()] (3.1)Tn hiu sng mang c biu thc:
x=Asin(2F1t) (3.2)
Tn hiu ASK:
v=x.*u (3.3)M phng trn M file:
clear all;clc;close all;F1=input('Enter the frequency of carrier=');F2=input('Enter the frequency of pulse=');A=3;%Amplitudet=0:0.001:1;
x=A.*sin(2*pi*F1*t);%Carrier Sine waveu=A/2.*square(2*pi*F2*t)+(A/2);%Square wave messagev=x.*u;subplot(3,1,1);
plot(t,x);xlabel('Time');ylabel('Amplitude');title('Carrier');grid on;subplot(3,1,2);
plot(t,u);xlabel('Time');ylabel('Amplitude');title('Square Pulses');grid on;subplot(3,1,3);
plot(t,v);xlabel('Time');
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS
ylabel('Amplitude');title('ASK Signal');grid on;
Hnh 3.10: Dng sng m phng tn hiu ASK trn Matlab
Tn hiu sng mang c bin 3V, tn s30Hz.
Tn hiu tin tc c bin 1.5V, tn s5Hz.
Tn hiu ASK c bin thay i theo tn hiu tin tc. y l trng hpc bit ca ASK gi l OOK(on off keying).
Khi V(t)=+1.5V th V(ASK)=3V
V(t)=-1.5V th V(ASK)=0V
Trong :
V(t) l bin ca tn hiu tin tc.
V(ASK) l bin ca tn hiu ASK.
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CHNG 3: GII THIU PHN MM VMCH V M PHNG PROTEUS