You are on page 1of 34

Bo co thc tp tt nghip

Mng Vin Thng

Tiu lun
MNG TRUYN HNH CP

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

LI NI U
Nn kinh t nc ta hin nay ang trong thi k pht trin, i i vi n l s
bng n v thng tin v truyn thng, trong c bit l ngnh Mng Vin Thng
v ang ngy cng khng nh vai tr ca mnh l mt phng tin thng tin i
chng c sc thuyt phc cao mang thng tin v hnh nh v m thanh n vi con
ngi. Thng qua cc chng trnh pht sng hng ngy, truyn hnh mang thng tin
v ng li chnh sch ca ng v Nh nc, tnh hnh kinh t, chnh tr, x hi,
gip ngi dn th hin c ting ni v thng tin ca mnh. L sn chi gii tr rt
b ch ca mi ngi. Bn cnh Mng Vin Thng cn gp phn vo vic m
rng quan h i ngoi ca t nc, giao lu vi cc nc trong khu vc v trn
th gii.
Nhng nm gn y, do nhu cu thng thc cc chng trnh truyn hnh cht
lng cao, ni dung phong ph ca con ngi ngy cng tng, cng vi s tin b
vt bc trong khoa hc cng ngh, cc mng truyn hnh cp c bit l truyn hnh
cp hu tuyn c nhng bc pht trin mnh m. Gi y truyn hnh cp khng
ch cung cp chng trnh truyn hnh cht lng cao m cn cung cp cc dch v
truyn s liu, truy nhp Internet tc cao v cc dch v tng tc.
Cng vi s i ln ca cng ngh truyn hnh th gii, truyn hnh Vit Nam
cng c nhng bc pht trin. Mt s dch v truyn hnh mi xut hin nh
truyn hnh cp v tuyn MMDS v truyn hnh qua v tinh phn no tho mn
nhu cu xem truyn hnh nhiu knh ca ngi dn. Cc chng trnh do MMDS
cung cp kh phong ph v hp dn, tuy nhin MMDS cng gp mt s hn ch ln
v vn ph sng, cht lng tn hiu v kh nng cung cp dch v. Truyn hnh
qua v tinh cng gp mt s vn nh: ng k dch v phc tp, chi ph thu bao
cao. V nhng l do ny m s ngi xem truyn hnh qua v tinh Vit Nam rt t.
V vy, c th p ng mt cch tt nht nhu cu xem truyn ca ngi dn,
ch c th l xy dng mt mng truyn hnh cp hu tuyn dn thng si cp tn
hiu t trung tm chng trnh n cc h dn. Nh , ngi dn c th xem cc
chng trnh c cht lng cao m khng cn phi nng cao cc ct anten thu tn
hiu, s khng cn hnh nh cc dn anten ln xn, cao thp trn cc nc nh, m
quan th s c ci thin.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

Thy c v tr tm quan trng ca Truyn hnh cp i vi x hi ha do


em chn ti Mng vin thng c th nghin cu v hiu thm v lnh vc
truyn hnh c su hn.
Do thi gian hon thnh bi bo co c hn, ngun ti liu tm hiu cha
c phong ph cng vi kh nng ca bn thn cn hn ch, chc chn bi bo co
khng khi c phn cn thiu st. Em rt mong c s gp ca cc thy c v cc
bn em c th hon thin hn bi bo co ca mnh.
Em xin gi li cm n su sc ti cc thy c gio ging dy em tn tnh
trong sut qu trnh hc tp em tip thu c tht nhiu kin thc. V c bit em
xin gi li cm n chn thnh n thy gio C Vn Thanh trc tip hng dn
v gip em hon thnh bi bo co ny!
Ph L, Ngy 20 Thng 04 Nm 2013
SV THC HIN
Nguyn Xun V

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

PHN I: L THUYT
CHNG I: TM HIU TNG QUAN V MNG TRUYN HNH
CP
1.1

Lch s pht trin ca truyn hnh cp ti vit nam


+ Ngay 20/9/1995, thanh lp Trung Tm Truyn Hnh Cap MMDS, anh du
mc u cua truyn hinh tra tin nhiu knh. Thang 12/1995 chuyn giao quyn quan
ly cng ty lin doanh SCTV (gia cng ty Du Lich Sai Gon Va ai Truyn Hinh Vit
Nam) v trung tm Truyn Hinh Cap.
+ Thang 12/1996, nng cp may phat song MMDS, tng s knh phat song t 4
knh ln 6 knh vi ban kinh phu song 40 km.
+ Ngay 25/04/1998, tt ca cac knh phat song qua MMDS u c khoa ma
va Trung Tm Truyn Hnh cap MMDS thc hin vic mua ban quyn hp phap cac
knh truyn hinh nc ngoai.
+ Nm 1999 SCTV tng s knh phat song MMDS t 12 knh ln 16 knh
trong o co 13 knh khoa ma.
+ Ngay 14/01/2000, thanh lp Hang Truyn Hinh Cap Vit Nam trn c s TH
cap MMDS chuyn t n vi s nghip co thu sang doanh nghip, co u t cach
phap nhn, hoach toan c lp, co con du va tai khoan ring.
+ Ngay 28/03/2001, hp tac vi cng ty in t tin hoc Hai Phong xy dng
Trung Tm Truyn Hinh Cap Hai Phong. Ngay 13/06/2001, thanh lp chi nhanh tai
Thnh Ph H Chi Minh. Thang 11/2001 Truyn Hinh Cap hu tuyn khu vc Ha
Ni chinh thc trin khai (chu yu s dung cap ng truc ).
+ Thang 04/2002, SCTV c tach ra khoi Hang Truyn Hinh Cap MMDS
thc hin nhim vu cua mt cng ty lin doanh. Ngay 05/06/2002, hp tac vi Thnh
Ph Hai Dng xy dng Trung Tm Truyn Hnh Cap Hai Dng. Ngay
24/09/2002, ai THVN ky thoa thun hp tac vi Cng ty in lc Vit Nam xy
dng h thng cap quang trn toan quc. Tai khu vc Ha Ni, Truyn hinh cap hu
tuyn tng dn s knh, cht lng tin hiu nng ln ro rt.
+ Ngay 17/02/2003, Trung tm dich vu ky thut TH cap VN c thanh lp trn
c s Hang Truyn Hnh Cap MMDS, tr thanh n vi s nghip co thu vi nhim
vu tp trung vao dich vu ky thut, phat trin mang cap va thu bao. Ngay 21/11/2003,
Tng giam c ai THVN i tn trung tm DVKTTH cap VN thanh Trung tm
KTTH cap VN, ban hanh chc nng nhim vu va c cu t chc. Ngay 17/08/2003,
Trung tm KTTH cap VN c chuyn giao c s ky thut h thng truy nhp co
iu kin va co thm nhim vu cung cp dich vu truy cp Internet cung vi cac dich
vu gia tng khac.
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

+ Nm 2004, H thng mang cap CATV ngay cang c m rng, vic s dung
h thng cap quang ngay cang phat huy tac dung tt, tao tin cho vic m rng
mi quan h hp tac va trin khai h thng truyn hinh tra tin vi pham vi ln.
Ngay 01/11/2004, trin khai truyn hinh s v tinh DTH hoan tt v chinh thc phat
song trn pham vi toan quc.
+ Nm 2005, VCTV thanh lp 4 chi nhanh trn ia ban Thnh Ph Ha Ni,
ngoai ra VCTV con hp tac vi 3 n vi khac trin khai nhanh chng mang cap
CATV khu vc Ha Ni. DTH tng trng manh me ca v doanh s ban thit bi va
thu bao, thanh lp c h thng phn phi trn ton quc tai 64 tinh thanh.
+ Nm 2006, VCTV tip tuc phat trin CATV tai cac tinh, thanh ph nh: Thai
Binh, Ninh Binh, Vung tau, Tin Giang, Phu tho. Ln u tin, VCTV ban ban quyn
cho i tac My va Canada 02 knh VCTV2 va VCTV4. Ngay 15/09/2006, VCTV
chinh thc c ai THVN giao quyn t chu tai chinh nhn s, tao iu kin tt
nht VCTV phat trin. Cung thi gian nay, ai THVN quyt inh giao nhim vu
kinh doanh quang cao trn truyn hinh tra tin cho VCTV.
+ Nm 2007 vi c ch qua ly va tai chinh thng thoang, quyn t chu cao, y
la nm bt pha cua VCTV. VCTV theo ui cac chin lc nng cao cht lng dich
vu va chinh sach u ai hp ly nht cho khach hang. Ngay 06/03/2007, Info TV
knh thng tin tai chinh kinh t knh truyn hinh chng khoan trc tip u tin tai
VN, do VCTV ky kt trin khai cung i tac Ocean Media chinh thc phat song.
VCTV nghin cu va chun bi cac an a ra cac goi san phm cng ngh cao
nh: IP TV, Mobile TV u t manh m cho DTH, xuc tin lin doanh vi i tac
nc ngoai nhm phat trin DTH ca v ni dung va ky thut.
+ Nm 2008 n u s kin Vinasat 1, VCTV d kin tip tc u t cho
DTH, xc tip lin doanh vi i tc nc ngoi nhm pht trin DTH c v ni
dung v k thut. Mng CATV tip tc c m rng thm cc chi nhnh ti H Ni
v mt tnh, thnh ph khc trn ton quc.
+ Nm 2010 Tuyn hnh cp thc hin mt cuc cch mng ngn ngi khi pht
sng Animax, knh chiu hot hnh anime 24/7 duy nht ti Chu . Tuy nhin v
sau knh ny b ct.
+ Nm 2011, 3 knh truyn hnh c sc : SCTV14, SCTV9, Truyn hnh an
ninh c gp mt trong h thng ca Truyn Hnh Cp Vit Nam
Thng 11/2011, Truyn hnh Cp Vit Nam chnh thc trin khai cung cp
dch v Truyn Hnh nt tiu chun mng Cp VCTV ti a bn H Ni.
+ Thng 2/2012, trn c s t chc, sp xp li Trung Tm K Thut Truyn
Hnh Cp Vit Nam, Tng Gim c i THVN c quyt nh s 189//Q-

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

THVN thnh lp cng ty TNHH mt thnh vin Truyn Hnh Cp Vit Nam
(VIETNAM CABLE TELEVISION CORPORATION).
Nm 2012, vi s xut hin ca knh VCTV 14-Lotte t Vit Home Shopping.
Knh mua sm trc tuyn ln nht ti Vit Nam nng tng s knh ln 64 knh
trn mng cp cng vi gn 100 knh truyn hnh trn h thng truyn hnh nt
tiu chun SD v nt cao HD.
Thng 5/2012, Truyn Hnh Cp Vit Nam m rng a bn cung cp dch v HD
VCTV ti a bn Thi Nguyn v Ph Th sau khi trin khai ti a bn H Ni.
Ngy 26/06/2012, nhn giy ng k kinh doanh.
Ngy 10/07/2012, Cng ty TNHH MTV Truyn Hnh Cp Vit Nam chnh thc lm
l ra mt ti khch sn Deawoo H Ni.
Thng 11/2012 Truyn Hnh Cp Vit Nam ng lot trin khai dch v HD trn
nhiu tnh thnh trong c nc (Qung Ninh, Hi Phng, Thi Bnh, Ngh An, H
Tnh, Qung Tr, Bnh Thun, An Giang, Tin Giang... ) v d kin s tip tc m
rng phm vi phc v thm nhiu tnh thnh trong c nc trong thi gian ti.
Vi nhng thnh tch t c, Truyn Hnh Cp Vit Nam nhn c nhiu
bng khen, c lun lu ca Th Tng Chnh Ph, ca Tng Gim c i THVN.
1.2 Khi nim v truyn hnh cp
Truyn hnh cp ra i nhm khc phc nhng hn ch ca truyn hnh sng, p
ng tt hn na nhng nhu cu, dch v ring l mi m m truyn hnh sng khng
lm ni. Truyn hnh cp thc hin theo nguyn tc tn hiu c truyn hnh trc
tip qua cp ni t u pht n u my thu hnh. Do c im m Truyn hnh cp
c th chuyn i nhiu chng trnh mt lc c th p ng nhu cu c th ca tng
ngi s dng. Ngoi ra, truyn hnh cp cn c th gii quyt mt lot dch v ca
x hi hin i m truyn hnh sng khng th thc hin.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

1.3 S tng quan mt h thng truyn hnh cp

Hnh: 1.1 S h thng truyn hnh cp


1.4 Trnh by u im v nhc im ca truyn hnh cp.
* u im:
- Ph tn s thng c s dng trong mng CATV 87-860MHz, vi rng ph
nh vy mng truyn hnh cp hu tuyn cung cp mt s lng knh hn hn so vi
truyn hnh cp.
- Trong mng CATV, tn hiu c truyn trong cp quang v cp ng trc do vy
hn ch s xm nhp ca nhiu v gim thiu c s nh ca thi tit ln cht
lng tn hiu.
- Cht lng mng truyn hnh cp hu tuyn khng b nh hng bi a hnh,
khng b che chn bi nh cao tng. CATV c bit ph hp cc th ng dn c.
- Mng CATV khng s dng anten gp phn tng v m quan cho cc thnh ph.
- C th tch hp cc dch v cng thm: thoi, internet, video on demand,... trn
mng truyn hnh cp.
* Nhc im:
- Vic trin khai mng cp hu tuyn tn rt nhiu chi ph, thi gian v cng sc.
- Mng cp CATV ch ph hp vi nhng khu ng dn c do vy khng th trin
khai cho mt khu vc rng ln.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

- Mc d cht lng tn hiu trong mng cp l kh tt nhng do s dng cng ngh


analog nn vn cn km hn nhiu hn so vi truyn k thut s.
1.5 Lm th no c th cung cp dch v HDTV
L Truyn hnh k thut s c nt cao vi nhng khch hng s dng dch v
HDTV s c tri nghim mt cng ngh m thanh v hnh nh th h mi.
Khch hng BTS s c thng thc cc knh truyn hnh nt tng cao t 4-5
ln so vi truyn hnh analog, hnh nh mu sc trung thc sng ng, h thng m
thanh s a knh 5.1 Vi dch v HD khch hng c cm gic nh c th mnh
trong nh ht hay rp chiu phim ngay ti trong ngi nh ca mnh.
s dng dch v HD khach hng cn phi mua b gii m k thut s STB-HD
do chnh Cng ty BTS cung cp, ng thi khch hng c th la chn hnh thc tr
ph thu bao theo thng hoc nm.
1.6 Tng lai ca truyn hnh cp
Trong qu trnh cnh tranh, mi nhn t phi t thay i, phi t lm mi, phi
bit pht huy nhng u im, li th ca mnh. Nghnh truyn hnh khng nm
ngoi quy lut . Mc d c nhiu u im nhng mng truyn hnh cp hu tuyn
cng bc l nhiu hn ch, c th ng vng trong cuc chy ua v cng ngh,
truyn hnh cp cn pht huy nhng u th vn c ca mnh.
Khng t ngi nhn nh rng HDTV l tng lai ca truyn hnh (HDTV
High Definition TV). Vi cng ngh HD ngi xem c tn hng nhng hnh nh
sc nt, r rng, mu sc trung thc nh c thm im nh trn tng cm v cht
lng m thanh cng tt hn nhiu .
Hu ht TV LCD c by tn trn th trng hin nay u h tr cng ngh HD.
Nh vy thit b u cui sn sng cho vic p dng cng ngh mi ny. Vn
hin nay ca nc ta l cha c nh cung cp no cung cp tn hiu truyn hnh theo
cng ngh mi ny. Vn hin nay ca nc ta l cha c nh cung cp no cung
cp tn hiu truyn hnh theo cng ngh HD. Cc nh cung cp dch v truyn hnh
cp vi c s h tng hin i c ca mnh hon ton c th a cng ngh HD vo
s dng.
Mt trong nhng u th ca truyn hnh cp hu tuyn l c th truyn tn hiu
theo c hai chiu. Chng ta hy khai thc u th ny bng dch v truyn hnh theo
yu cu (Video on demand). On demand c ngha l ngi xem c th xem danh
sch cc chng trnh la chn chng trnh mun xem v khng b b buc v
thi gian xem.
Cng ngh truyn hnh HD v dch v On demand l hai vn m cc nh
cung cp dch v hon ton c th trin khai trong thi gian sp n nng cao v

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

th v sc cnh tranh ca mnh. Tip sau chng ta cn quan tm n vic tch hp


nhng ng dng Internet vo trong truyn hnh cp.
Vi mt Set-Top-Box v remote control ngoi vic c th xem hng trm knh
truyn hnh HD, chng ta cn c th lt Web, xem cc on video cht lng cao
t youtube hay xem nhng bc nh t Flickr. Thm ch thng qua mng cp ny
nhng giao dch chng khon s c thc hin thng qua nhng ci chm tay trn
mn hnh TV. Tng lai ca nghnh truyn hnh cp hu tuyn cn pha trc.
1.7 Cc thit b truyn dn
1.7.1 Mng cp quang
Mng cp quang c thit k theo hnh Ring, star. Bao gm cc vng quang v
s dng cc loi cp 60, 48, 24, 12, 6 si quang.
Vi mi vng Ring u c mt s Node quang xc nh. Ti H Ni th: Vng 1
c 12 Node quang, vng 2 c 12 Node quang, vng 3 c 11 Node quang, cn vng 4
c 12 Node quang.
Cp quang l cp c cu to t nhiu si cp quang. S lng si cp quang
trong mt cp ti thiu l 1 n ti a l hng nghn si ty vo mc ch s dng,
thit k ca tuyn cp. Si cp dng cho truyn hnh v vin thng ni chung l si
n mode.
Cp quang bao gm cc phn: si cp quang, ng nha ng si cp, si chu
lc, v cp, dy tng cng. Nu l cp treo ngoi tri th c thm dy chu lc, c
th l dy kim loi hoc dy phi kim loi.
V bc cp thng lm bng cc vt liu PVC, c kh nng chu n mn ha
cht, chu c tc ng nhit, bo mn mi trng...
ng chu lc lm bng nha PVC, bn trong ng c mt lp du c bit
trnh khi vn chuyn si cp v vo ng gy ra xc lp b mt bo v ca si cp
quang. ng ny cn c gi l ng lng v n khng m cht ly si cp quang m
cn c mt khong tha nht nh. Mc ch l khi thi cng ta c th cng cp nhng
si cp bn trong hu nh khng chu tc ng ca lc cng ny. Bn cnh , ta c
th un cong cp vi mt gc nht nh cng khng lm nh hng n si cp bn
trong.

1.7.2 Node quang


Phn ni ghp gia cp quang v cp ng trc gi l node quang. Node quang l
loi thit b c s dng cho vic bin i tn hiu quang thanh tn hiu in.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

HnHHnh: 1.3 S khi tng qut Node quang


- Chnh suy hao c nhim v chnh mc suy hao tn hiu di tn cao cho suy
hao thp v chnh suy tn hiu tn s thp cho suy hao nhiu hn (iu chnh
mc suy hao di U v V bng nhau).
- Chnh Equalizer c nhim v chnh mc tn hiu tn s cao hn mc tn
hiu tn s thp.
- Chiu i v v ca tn hiu c m t nh hnh v.
- Di tn chiu i l: 87 860 MHz.
- Di tn chiu v l: 0 65 MHz.
- Hin nay trn mng truyn hnh cp Vit Nam lp cc Node quang ca cc
hng Scientific Atlanta, FOX v GAMMA
1.7.3 Khuch i
L thit b tch cc, c nhim v b p li nhng suy hao trn thit b phn chia,
cp ng trc v cn chnh lch mc nh gia cc knh trong h thng.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

Hnh: 1.5 S khi ca khuych i


- Chnh suy hao c nhim v chnh mc suy hao tn hiu di tn cao cho suy hao
thp v chnh suy tn hiu tn s thp cho suy hao nhiu hn (iu chnh mc suy
hao di U v V bng nhau).
- Chnh Equalizer c nhim v chnh mc tn hiu tn s cao hn mc tn hiu
tn s thp.
- Chiu i v v ca tn hiu c m t nh hnh v.
- Mc tn hiu vo l: 74 78 dBV.
- Mc tn hiu ra l: 106 110 dBV (i vi Danlad h s khuych i 32dB).
Hin nay trn mng truyn hnh cp Vit Nam dng cc b khuch i ca cc hng :
Scientific Atlanta, Danlab, Maiwei.
Tn hiu i vo khuch i i qua b lc lai ghp (diplex filter). B lc lai ghp ny
c nhim v lc tch di tn cao t 87 n 860 MHz, c th iu chnh mc tn hiu
v dc ca di tn hiu vo b khuch i trong khong cho php ca nh sn
xut. Tn hiu c khuch i c di t 87 n 860 MHz, sau tn hiu c a
qua b lc lai ghp u ra v c tip tc truyn trn mng cp.
Cn tn hiu Internet s i theo chiu ngc li. Tn hiu t thu bao c pht
di tn thp t 5-65 MHz. Tn hiu c a n u ra ca khuch i (chnh l u
vo ca tn hiu v) ti y tn hiu cng c lc thng thp v ch ly di tn t 565 MHz. Tn hiu c khuch i v cng c th iu chnh nghing v suy

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

hao u ra ca ng v. Sau tn hiu cng c a qua b lc lai ghp a


tip ln b khuch i tng trn hay node quang a v CMTS.
C 3 loi khuch i:
+ Khuch i trc chnh: c h s khuch i khng ln, c nn nhiu ti thiu.
+ Khuch i nhnh: c h s khuch i ln, nn nhiu cho php
+ Khuch i m rng: h s khuch i ti a cho php.
1.7.4 Cp ng trc
Sau khi tn hiu quang c chuyn thnh tn hiu in, th n i qua mng cp
ng trc n tn cc thu bao.

Hnh: 1.7 Cu to cp ng trc


- Truyn c tn hiu in t tt c cc di tn s. Tn hiu truyn trn b mt ca
li cp.
- H s suy hao tn hiu ph thuc vo cc yu t: tn s tn hiu, vt liu lm dy
cp, kch thc li cp, hnh dng ca li cp, lp v kim loi. Tn s cng cao th
suy hao cng ln trn cng 1 khong cch dy dn. Vt liu c in tr xut cng nh
th suy hao ca cp nh (v d ng, bc...). Li cp cng nh th suy hao cng ln.
Li cp cng nhn th suy hao cng t. Nu li cp g gh th suy hao cng nhiu v
kh xc nh gia cc tn s. V bc kim phi c tit din l hnh trn, nu ti 1 im
no , v bc kim b bin dng th s c hin tng suy hao do tn x v phn x.
- in tr c tnh i vi tn hiu cao tn l 75 .
- C kh nng chng nhiu in t mi trng cao, tn hiu cao tn truyn trong li
cp pht x ra bn ngoi mc rt thp. Kh nng chng nhiu v chng pht x
ph thuc vo lp v kim loi.
Cc loi cp:
- Cp trc chnh QR540: y l cp ln nht dng truyn tn hiu trn cc ng
trc chnh. c im ca loi cp ny l c mc suy hao thp 0.0565 dB/m. Nn n
c dung ko cc ng trc chnh, chy di.
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

- Cp ng trc RG11: y l loi cp dng ch yu truyn tn hiu ra t cc


khuych i chnh v chia DC ti cc khuych i nhnh, hay dng ghp ni gia
cc thit b truyn dn khc nh: Tap, DC
- Cp RG11 c suy hao l 0.13 dB/m.
- Cp ng trc RG6: y l loi cp dng dn tn hiu n tn cc thit b thu
(nh TV) ca thu bao.
- suy hao ca cp RG6 l 0.2 dB/m

Hnh: 1.8 Cp QR540, RG11 v RG6


1.8 S nguyn l v bng tn ca truyn hnh cp.

Headend Cp trung k Node


quang

Cp nhnh

Hp thit b
thu bao

Cc tn hiu u vo l cc chng trnh truyn hnh, c s l v chuyn thnh


tn hiu quang thng qua Headend. Sau tn hiu quang c truyn qua mng si
quang, ti im cui l cc Node quang. Ti node quang tn hiu quang c chuyn
thnh tn hiu in v truyn qua h thng cp ng trc n tng thu bao.

Hnh: 1.9 Di tn ca h thng truyn hnh cp.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

Ta thy, di tn ca h thng truyn hnh cp chia lm 3 di tn r rt. Vi di tn


th u c s phn chia r rng.
- Di tn t 5 - 65 MHz. y l di tn s dng cho vic truyn tn hiu tr v trung
tm x l (headend), nh cho vic truyn hnh trc tip..
- Di tn 87 550MHz: Dng truyn i (t Headend) cc knh truyn analoque
ti cc thit b u cui (Hp thit b thu bao).
- Di tn 550 860 MHz: Dng truyn i (t Headend) cc knh truyn hnh
Digital ti cc thit b u cui (hp lp thu bao).
1.9 Cu to mt mng truyn hnh cp
1.9.1 Cu to mng truyn hnh cp hu tuyn HFC
Mng HFC (Hybrid fiber / coaxial Network) l mng kt hp cp quang v cp
ng trc, s dng ng thi cp quang v cp ng trc truyn v phn phi tn
hiu. Vic truyn tn hiu t trung tm n cc mode quang l cp quang cn t
mode quang n thu bao l cp ng trc.
Cu trc mng cn ph thuc vo nhiu yu t: a l, phn b dn c v lin quan
n nng cp h thng... Nhng hu nh cu trc mng u c cu trc vng, sao,
chui.
* H thng trung tm

Hnh: 1.10 S h thng Headend


Headend l ni thu nhn tn hiu t nhiu ngun khc nhau ( tn hiu qung b,
v tinh, tn hiu sn xut chng trnh ) Sau khi qua cc bc x l nh: iu ch,
phn knh, m ha , trn... Tn hiu c a ra mng truyn dn v phn phi n
cc thu bao.
* Mng truyn dn v phn phi tn hiu
L mi trng truyn dn Headend n cc h thu bao. Trong truyn hnh cp
hu tuyn HFC, mi trng truyn dn l cp quang, in hnh l mt hay mt s
vng cp quang kt ni gia HE s cp v cc HUB s cp, trong mt s trng hp

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

khc th vng th cp li lin kt gia cc HUB s cp vi cc HUB th cp t cc


node quang FN c lin kt vi cc HE theo cu trc hnh sao.
Ngy nay mng truyn dn HFC tr thnh s la chn ca phn ln cc nh
cung cp dch v qua mng cp trn th gii bi nhng u im ni bt ca h
thng...

Hnh: 1.11 Mng truyn dn HFC


Tn hiu t trung tm qua b chuyn i in quang thnh tn hiu quang sau
c truyn dn qua cp si quang ti cc HUB. Ti cc im HUB c th l mt
trm thu pht li nu nh cung cp tn hiu cho mt phm vi ln (gia hai thnh
ph), c th ch l b chia quang thng thng chia tn hiu quang ti cc
Node quang. Tu thuc vo yu cu an ton ca h thng m tn hiu t trung tm
truyn ti ti cc HUB c thit k theo cu trc mng vng (Ring) hoc hnh sao
(Star). Tn hiu sau Node quang c chuyn i t quang sang in sau c
truyn dn v cp ng trc truyn dn tn hiu n tng h thu bao qua mng
cp ng trc nh cc b khuch i tn hiu RF, cc b chia cao tn .
* Mng truy nhp HFC
L mng lai gia cp quang v cp ng trc trong c s dng cc thit b tch
cc ( b khuch i cao tn ) trn mng ng trc.
- c im mng HFC
+ p ng c yu cu xy dng theo 1 hay 2 chiu
+ Mng ng trc chim t l cao trong tng th mng
+ Mng ng trc chia lm 3 cp

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

+ Cu trc trc chnh bao gm : cp ng trc chnh, khuch i trc, b chia tin
hiu trc
+ Cp trc nhnh bao gm: Cp ng trc nhnh, b khuch i nhnh, b chia trc
nhnh
+ Cp mng thu bao: cp ng trc thu bao. TV
+ C th phc v t 1500 2000 thu bao/node quang
- u im ca HFC
+ Cht lng tn hiu tt do khng s dng cc b khuch i
+ Do khng s dng cc b khuch i cao tn nn vic thi cng lp t, vn hnh
d dng hn.
+ Cc thit b t ng c kh nng truyn hai chiu nn n nh mng vn cao khi
trin khai mng hai chiu.
+ S lng thu bao/node quang nh nn c kh nng cung cp tt dch v hai chiu
vi tc cao.
+ Gim chi ph cp ngun cng t in, bo dng, thay th cc thit b tch cc.
- Nhc im ca HFC:
+ Kh nng bao ph ca mt node quang nh do khng s dng khuch i.
+ Yu cu node quang s dng phi c cng sut ln, cht lng cao, n nh.
+ Ph hp vi khu vc c quy hoch tp trung, khng ph hp vi a hnh Vit
Nam.
+ Yu cu v chi ph cao.
1.9.2 Thit b truyn dn trong HFC
1. B khuch i hai chiu.
Trong phn mng cp ng trc, cc b khuch i hai chiu c s dng bao gm
hai loi.
- B khuch i phn phi ( khuch i tn hiu RF v t vo 2 hoc 4 u cp ra
khc nhau)
- B khuch i ng dy m rng Line Extender Amplifier mt h thng HFC
hin i thng c t 4 n 6 b khuch i cho tng khuch i RF sau mi node.
a s cc b khuch t iu chnh b p nhng thay i khc nhau theo nhit
suy hao v p ng tn s

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

Hnh: 1.12 B khuch i 2 chiu


2.Cp quang v cp ng trc trong mng.

Hnh 1.13 Kin trc mng truyn hnh cp truyn dn bng cp quang v cp
ng trc
3. Cp quang.
Mi cp quang c cha t 12 n 14 si quang ty theo kch c mi loi cp.
Loi si cp c s dng y thng l si n mode-SM c suy hao khong 0,4
dB/km bc sng hot ng l=1310 nm hoc suy hao 0,25 dB/km l=1550 nm
(mc suy hao ny n nh trong di nhit thng v c lp vi di tn s v
tuyn).

Hnh: 1.14 Hnh nh v cu to ca cp quang


4. Cp ng trc.
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

- on xut pht t mode quang to ra c ng knh ln nht (t 0,78 n 1,09 cm)


cht lng tt nht, suy hao 45 dB/km 750 MHz hoc 9dB/km 40 Mhz.
- on cui gn st nh thu bao di khong 25 cm 50 cm, ng knh nh, suy
hao khong 114 dB/km 40 MHz (mc suy hao ny ph thuc vo nhit v chiu
di ca cp).

Hnh: 1.15 Cp ng trc v cu to ca cp


5.Cu r (Tap)
Mi cu r c 2 phn t chc nng chnh : L khi ghp nh hng v b chia
cng sut. Trong b chia cng sut tn hiu ty theo s lng cng ca cu r (c
th l 2, 4, 8...) cn khi ghp nh hng c nhim v i hng 1 s tn hiu u
vo xc nh.

Hnh: 1.16 B chia tn hiu truyn hnh cp Pacific 1 vo 4 ra


6. Node quang.
L phn t nm trn ng ranh gii gia cp quang v cp ng trc, c nhim
v c bn chuyn i tn hiu in cho ng xung ( v ngc li ) khuch v phn
phi trn
mng cp ng trc vi
3 hoc 4
u ra mi node.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng


Hnh: 1.17 Node quang

Hnh: 1.17 Node quang


7. Thit b kt cui truyn hnh STB (Set-Top-Box)
Thit b kt cui thu tn hiu truyn hnh vi hai loi: STB tng t v STB s .
STB tng t cho thu bao thu cc knh truyn hnh tng t nh mng HFC thay v
cc knh pht qung b v tuyn mt t trc y. Thng qua n cc nh iu hnh
cp cung cp dch v xem phim v mt s dch v c bit khc theo hnh thc thanh
ton ngay IPPV v s dng in thoi lm ng ln cho cc hot ng tng tc
mng. n 1996 STB s c gii thiu vi mt s chc nng c bn:
+ D tm knh s v cc dch v video,tng t trong cc di tn ng xung .
+ Gii iu ch knh s thu c. iu ch knh s pht ln.
+ Gii m / M ha cc knh chn.
+ Qun l bo hiu thu bao t Headend.
Cung cp giao din thu bao cho ngi s dng. Gn y cc STB ci tin c
trin khai bi Motorola/ General Instrument. Cc STB ny c cha cc b d sng
kp v modem cp tch hp bn trong, cho php thu bao s dng dch v truyn
hnh v dch v Internet bng rng nh: IP telephoy, IP video phone , Interactive
games. Lc ny STB ci tin hot ng nh mt cng gia nh RGW.
Phn pht cc gi giao thc IP n cc thit b bn ngoi nh l IP voice, IP video
phone.
Truyn ti, x l, gii m cc tn hiu truyn hnh c phn gii cao HDTV.

Hnh: 1.18 Set Top Box trong truyn hnh cp


SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

8. Modem cp CM (Cable Modem)


L thit b nm trong thu bao cho php truy nhp n cc mng my tnh (thng
l mng Internet) trn phng tin vt l dng cho truyn hnh. C ba loi modem
cp:
+ Loi khi cm ngoi : kt ni vi my tnh thng qua kt ni Ethernet ( c th c
nhiu my tnh cng kt ni vo mng Ethernet, lc ny modem cp cn c chc
nng ca mt b nh tuyn ) hoc giao din kt ni USB.
+ Loi card cm nm trong: thng l dng cm trn PCI cho my tnh. Loi ny c
gi thnh r nht song ch dng c cho my tnh bn cn s phi c s thit k
khc cho dng my tnh MAC v my tnh xch tay.
+ Loi th ba ca modem cp l dng c tch hp bn trong cc STB ci tin
tng tc nh trnh by trn.

Hnh:
1.19 Modem cp
Hnh: 1.19 Modem cp
9. H thng kt ni modem cp CMTS
H thng ny nm trong Headend, thuc v bn kia ca mng so vi modem
cp. L thit b kt ni cho ng t pha thu bao n ch l cc Headend ca cc
cng ty cp, do CMTS cng c coi l giao din gia cc modem cp v mng
Internet IP.
+ CMTS c nhiu chc nng ging nh mt DSLAM trong h thng DSL.
+ CMTS n lng ng ln t mt nhm thu bao trn mt knh n v nh
tuyn n n ISP kt ni vo mng Internet.
+ Mi CMTS cha mt hoc nhiu card ng dy modem ( CMLC ). Cc CMLC
chuyn cc dng s liu IP thnh cc tn hiu RF ng xung ( n nh thu bao )
sau a qua b nng tn a cc knh tn hiu vo mt knh tn hiu vo
mt knh xc nh v ghp chng vi cc tn hiu truyn hnh v trnh t ngc li
vi ng ln. Mt s server trong mng modem cp my ch DHCP (Dynamic
Hort Protocol) c xc nh bi RF2181. Server ny cung cp cc a ch Ip theo
nhu cu cho modem cp v cc thit b PC theo sau n. My ch ToD ( Time of Day)
c xc nh bi RFC 868, c nhim v l gn cc tem thi gian cho cc s kin
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

iu hnh h thng. My ch TFP ( Trivial File Protocol ) c xc nh bi RFC


1350 ng k v ti v cc file cu hnh modem cp cho cc dch v thu bao
ring l.
10. H thng IP Phone
y l h thng s dng giao thc IP truyn tn hiu thoi qua mng vin
thng trong giao thc IP l giao thc chun cho lp chuyn mch gi trong mng
LAN, WAN,... Mng IP mng s liu c lp vi lp vt l. Vic tch hp c h
thng truyn ti thoi vo mng bng rng HFC c ngha ln trong vic to thun
li HFC thc hin mt xa l thng tin thc s truyn mi loi tn hiu : voice,
data, video. H thng VoIP ny s dng thit b kt cui l my in thoi IP phone
hoc my in thoi truyn thng POTS phone kt ni vi mt modem cp / mt
STB s. My IP phone l thit b kh mi. N khng kt ni n mt tng i s hu
no m kt ni n cng Ethernet chun trong mt modem cp / mt STB s / mt
PC trong nh. My IP phone hot ng nh mt thit b IP tiu chun v c a ch
IP ring ca n. kt ni mt POTS phone n mt modem cp / STB s th phi
c cc modun giao din mi c pht trin v gn vo trong cc modem cp / STB
s cung cp chc nng ny.
11. H thng thit b thu bao v tnh cc dch v.
im ct yu nht i vi cc nh cung cp dch v truyn hnh tr tin l c
th qun l truy nhp v tnh cc ca thu bao theo dch v. Mt phng php ph
thng v hiu qu nht l s dng cc thut ton m ha tn hiu ( ch nhng thu
bao c nh cung cp dch v cho php mi c th c gii m tn hiu xem ).
H thng qun l truy nhp ca thu bao v tnh cc c gi l h thng truy nhp
c iu kin.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

CHNG II: NU CC LOI DCH V VIN THNG CUNG


CP TRUYN HNH CHO KHC HNG
2.1 Khi nim dch v vin thng.
La dich vu truyn a tc thi thng tin cua ngi s dung di dang ky hiu,
tin hiu, s liu, ch vit m thanh, hinh anh thng qua mang vin thng hoc
internet ma khng lam thay i loai hinh hoc ni dung thng tin c gi va nhn
qua mang.
2.2 Dich vu thoai.
2.2.1 Dich vu in thoai.
1. Dich vu 171 tra sau
La loai dich vu in thoai theo giao thc IP (Internet Protocol) vi pham vi lin
lac lin tinh, quc t tng t dich vu in thoai lin tinh, quc t thng thng.
Dich vu Goi 171 cung cp cho khach hang cac cuc goi lin tinh va quc t vi gia
re, cht lng mc chp nhn c.
Cach quay s tng t nh goi in thoai lin tinh va quc t, chi khac la phai
thm ma truy nhp 171 trc cach goi thng thng. Cu th:
- Goi lin tinh: 171.0.Ma vung.S thu bao
- Goi quc t: 171.00.Ma nc.S thu bao
2. Dich vu 1717 tra trc
La dich vu in thoai dung the tra trc co cht lng am bao va cc phi hp
ly dung goi in thoai lin tinh, t nc ngoai v Vit Nam.
Vi cac mnh gia the t 30.000 n 500.000, khach hang co th lin lac ng dai
t bt c may in thoai nao, chi phi cho cuc goi se c tr vao tai khoan tinh trn
mnh gia the va ngi chu thu bao se khng mt mt khoan chi phi nao cho cuc
goi o. Mi the 1717 se co mt ma s b mt quan ly tai khoan cua minh.
Danh sach cac nc ma khach hang co th s dung the Goi 1717. thc hin
cuc goi, ngi s dung thc hin theo cac bc sau:
- Bc 1: Quay s 1717.
- Bc 2: Bm phim 1 s dung dich vu vi cac thng bao bng Ting Vit; bm
phim 2 s dung dich vu vi cac thng bao bng Ting Anh. Trong trng hp
khach hang bm s khac vi s 1 hoc 2 thi h thng se yu cu khach hang nhp lai
s khac, nu thao tac qua 3 ln, h thng se t ng ngt cuc goi.
- Bc 3: Nhp ma s bi mt ghi trn the tra trc. Khach hang se nhp ma s bi mt
cua the (VD: 012345678901), kt thuc bng phim #.
- Bc 4: Bm s in thoai cn goi.
+ Goi i quc t: 00 + ma nc + ma vung + s T cn goi.
+ Goi trong nc: 00 + ma vung + s T cn goi.
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

2.2.2 Dich vu in thoai IP


Dich vu thoai c inh trn nn IMS em n cho cac t chc va doanh nghip co
nhiu chi nhanh trn toan quc mt trai nghim kt ni hoan toan mi. Mt h
thng mang s dung giao thc IP cho phep khach hang thit lp cac cuc am thoai
gia cac may in thoai, cac may tinh ca nhn (PC) trong ni b va vi cac thu bao
thng thng khac.
- Cho phep rut ngn thi gian thit lp cuc goi trong cac dich vu nh nhn tin tc
thi, nhn noi, khng cn phai bm u s lin tinh / s in thoai cn goi ma chi
cn s ni b.
- Co th d dang c s dung nhng dich vu gia tri gia tng trn in thoai c inh
vi cam nhn cht lng dich vu vin thng mi.
- Tit kim chi phi khng phai tra cc phi cho cac cuc goi ni b, bo c chi phi
u t va nhn vn hanh h thng in thoai ni b, tng ai PBX.
- Cht lng tt, cht lng dich vu cao hn so vi h thng in thoai PBX, nhiu
tinh nng linh hoat.
2.3 Dich vu phi thoai
2.3.1 Dich vu truyn hinh hi nghi.
Hi ngh truyn hnh (Video conference) l mt bc pht trin t ph ca cng
ngh thng tin, cho php nhng ngi tham d ti nhiu a im khc nhau c th
nhn thy v trao i trc tip vi nhau qua mn hnh tivi nh ang hp trong cng
mt cn phng.
Vi s pht trin nhanh chng ca h tng mng NGN ca VNPT, dch v Hi ngh
truyn hnh ang dn tr nn ph bin Vit Nam v l gii php hiu qu gip cc
t chc, doanh nghip tit kim thi gian, chi ph di chuyn m vn m bo v tng
cng hiu qu hot ng.
- Hi nghi truyn hinh cho phep t chc cac cuc hop trc tuyn gia cac vn phong
chi nhanh cac vung ia ly khac nhau, giup tit kim thi gian va chi phi di chuyn,
n , mua ve i vi cac thanh vin xa.
- Hi nghi truyn hinh cho phep trao i ngay lp tc vao bt ky luc nao, rt hiu qua
khi kinh doanh nghip cn x ly cac tinh hung mi, giai quyt cac s kin bt
thng.
- Giai phap tao iu kin d dang hn cho nhng ngi tham gia cuc hop, bi vi
mi ngi tham gia u tn dung tt nht hoan toan canh cua minh, cho phep nhiu
ngi co th tham gia cuc hop hn, nng cao cht lng cuc hop.
- Vi cac thit bi lu tr ngoai kt ni vao h thng, toan b ni dung cuc hop se
c lu lai ro rang va chinh xac di dang cac oan phim.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

- Tich hp c vi cac chng trinh email va t lich thng dung nh Microsoft


Outlook, cho phep thit lp lich hop mt cach d dang va gi li mi n cac i tac
khac qua email.
- S dung n gian, d dang goi va tham d hop. Cac khach hang chi cn khi tao va
tham d cuc goi bng mt vai thao tac.
- H thng co tinh bao mt.
2.3.2 Dich vu th in t.
Th in t, hay email (t ch electronic mail), i khi c dch khng chnh
xc l in th, l mt h thng chuyn nhn th t qua cac mang may tinh
Email l mt phng tin thng tin rt nhanh. Mt mu thng tin (th t) c th
c gi i dng m ho hay dng thng thng v c chuyn qua cc mng
my tnh c bit l mng Internet. N c th chuyn mu thng tin t mt my
ngun ti mt hay rt nhiu my nhn trong cng lc.
Ngy nay, email chng nhng c th truyn gi c ch, n cn c th truyn
c cc dng thng tin khc nh hnh nh, m thanh, phim, v c bit cc phn
mm th in t kiu mi cn c th hin th cc email dng sng ng tng thch
vi kiu t HTML.
2.3.3 Dich vu Internet trn mng truyn hnh cp
L s hp tc gia Truyn hnh cp Vit Nam v Cng ty CP h tng vin thng
CMC (cmc Telecom) cung cp dch v Internet trn ton b h tng mng truyn
hnh cp trn ton quc.
Khch hng ca Truyn hnh Cp vit Nam hon ton d dng kt ni Internet truyn
hnh cp vi tc ng truyn tn hiu cao v gi thnh cnh tranh hn so vi cc
dch v Internet khc. Ch vi mt ng truyn tn hiu, ngoi cc gi dch v cht
lng v truyn hnh cp, truyn hnh SD, HD m Truyn hnh Cp Vit Nam ang
phc v khch hng th dch v Internet tc cao v tin ti tch hp nhiu dch v
gi tr gia tng khc: thng mi in t, o to t xa, gim st h tr an ninh, cc
chng trnh gii tr theo yu cu... chc chn mang ti cho nhiu tin ch hn cho
khch hng, gp phn a dng ha hnh thc gii tr v tha mn nhu cu thng tin
a dng ca ngi dn.
2.3.4 Dich vu truyn hinh theo yu cu.
1. Phim truyn
Tha thch la chn phim trc tip t th vin phim khng l gm nhiu th loi
nh phim hnh ng, hi, tm l x hi,... t kinh in n hin i, thuc cc quc
gia khc nhau vo bt c thi im no.
Khng ch dng li vic xem phim n thun, bn c th xem cc b phim theo
yu thch vi rt nhiu tnh nng u vit:
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

- Kha cc phm c ni dung khng ph hp vi tr em.


- Xem trc ni dung gii thiu ca mi phim
- Xem li b phim nhiu ln.
1. m nhc
Gip bn tn hng giy pht th thi sau gi lm vic cng thng vi danh sch
cc bi ht lin tc c cp nht.
- Nghe nhng bi ht yu thch, nhng bi ht mi nht thuc mi th loi.
- Xem cc Video clips ca nhc vi cht lng hnh nh cao.
2. Karaoke
L dch v cho php bn ht Karaoke ngay ti nh vi cht lng m thanh v
hnh nh hon ho.
3. Pht thanh.
Bn c th la chn v nghe cc chng trnh pht thanh trong nc, quc t qua
h thng. Bn c th thng thc nhng chuyn mc pht thanh yu thch ca mnh
vo bt k thi im no trong ngy.
4. Game.
L dch v cho php bn la chn v chi game trn mn hnh tivi rng ln ngay
ti nh ca mnh vi hnh nh sng ng v giao din bt mt mang phong cch hin
i. Bn c th la chn game t danh sch sn c. S lng game phong ph v
c cp nht lin tc. Ni dung game hp dn vi nhiu th loi game nh: th
thao, gii tr, hnh ng, vui nhn, phiu lu...
5. Chia s hnh nh.
Cho php ti nh v clip yu thch chia s cho mi ngi cng xem v thng
thc.
6. Thng tin cn bit.
Cung cp nhng thng tin hu ch, nng hi nht v mi kha cnh ca cuc
sng: thi tit, giao thng, gi c th trng, thng tin chng khon, bt ng sn, ...
7. Tip th truyn hnh.
Mang n cho bn nhng thng tin v sn phm, dch v nh gi c, mu m,
a im giao dch mua bn, gip bn c th la chn v a ra quyt nh mua sm.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

CHNG III: TNH HNH THC TP TI C S V NHNG


KT QA T C
3.1 Gii thiu v Cng Ty C Phn in T Tin Hc HEREVN
3.1.1 Gii thiu chung:
Cng ty c phn in t tin hc HEREVN c thnh lp v cp php bi s k
hoch v u t thnh ph H Ni, s giy php 0105414093 cp ngy 19/07/2011.
Do nhng c ng c nhiu nm hot ng trong lnh vc cng ngh thng tin, in
t vin thng ti Vit Nam sng lp. Ngay t khi mi thnh lp ban gim c Cng
ty nh hng xy dng v pht trin HEREVN vi nt vn ha doanh nghip to
nn s khc bit v cc chnh sch m bo quyn li ca khch hng. Cng vi
i ng k thut chuyn nghip, nng ng, nhit tnh Ha hn nhiu trin vng
pht trin v chiu su v khng ngng nng cao trnh chuyn mn p ng
nhu cu ca th trng.
3.1.2 Gii thiu v Phng K Thut
3.1.2.1 S t chc Phng K Thut
T K Thut
Phng Lnh
o
K Ton

Hnh 3.1: S phng K Thut


3.1.2.2 Nhim v v chc nng ca Phng K Thut
1- Lnh o Phng
Chu trch nhim c nhn trc lnh o Trung tm v ton b hot ng ca
phng mnh.
Chu s ch o trc tip ca Gim c hoc Ph gim c c phn cng.
Ch o v iu hnh mi hot ng ca n v mnh thc hin tt nhim v c
giao theo ng k hoch.
Chu trch nhim v vic thc hin k hoch kinh doanh, cng ngh k thut, cht
lng cc cng trnh c giao ca phng mnh.
Phn cng cng vic v theo di mi hot ng ca cn b cng nhn vin do mnh
ph trch.
i din cho phng trong quan h phi hp vi cc n v ca trung tm khi gii
quyt cc cng vic lin quan.
Kim tra v n c cn b cng nhn vin v ngi lao ng hon thnh nhim
v c giao.
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

2- T sa cha.
Kim tra cc thit b khi hng hc, tm v pht hin nhng li xy ra trong cc
thit b ngng hot ng, sa cha cc thit b...
3.2 H thng sa cha ca phng K Thut.
3.2.1 S Tivi mu.

Hnh 3.2: S khi tng qut Tivi mu


- Nhm 1: C chc nng to nh sng trn mn nh. Bao gm khi ngun nui, khi
qut dng v khi qut mnh, nhm ny hot ng trc.
- Nhm 2: C chc nng thu v x l tn hiu hnh nh v m thanh. Bao gm b
knh & trung tn, khi chuyn mch AV, khi x l tn hiu chi, khi gii m mu,
khi khuch i cng xut sc v khi ng ting, cc khi trong nhm ny hot
ng sau nhm th nht.
Khi ngun: C nhim v cung cp hai in p mt chiu n nh l in p
B1=110V cho mch cao p v p B2=12VDC cho mch dao ng dng v gim
xung 5VDC cho mch vi x l, in p u vo ca khi ngun l in xoay chiu
AC50Hz c th thay i trong phm vi rt rng t 90V n 280V.
Khi qut dng: Nhim v ca khi qut dng l iu khin bin th cao p
hot ng to ra cc mc in p cao cung cp cho n hnh nh in p
HV( Height Vol) cung cp cho cc Ant khong 15KV, in p Pocus cung cp cho
li G3 khong 5000V, in p Screen cung cp cho li 2G khong 400V, in p
Heater 4,5V hoc 6,3V cung cp cho si t, xung qut dng cung cp cho cun li
dng.
Khi qut mnh: Nhim v ca khi qut mnh l cung cp cho xung mnh cho
cun li tia, li tia in t qut theo chiu dc.
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

B knh v trung tn: B knh l thu tn hiu song mang t i pht thng qua
Anten, sau i tn v tn hiu chung IF dng khuch i. Trung tn l khuch
i tn hiu IF ln bin ln sau tch sng ly ra tn hiu Video tng hp.
Cuyn mach AV: L tip nhn thm tn hiu Video t bn ngoi nh tn hiu ca
u VCD.
Mch x l tn hiu chi: L khuch i tn hiu Y, thay i bin v in p
thm (thnh phn mt chiu) ca tn hiu Y

chc nng chnh tng phn v

sng ca nh, khi mch chi khng hot ng s sinh hin tng mt hnh, mt
nhiu.
Mch gii m mu: L gii m tn hiu song mang C ( Choma ) ly ra 3 tn
hiu mu thiu chi R-Y, B-Y, G-Y, cung cp cho mch ma trn khi phc li ba
tn hiu mu a vo n hnh, nu hng khi gii m th ch c tn hiu Y (en
trng) i vo n hnh.
Mch ma trn v K cng xut sc: thng thng mch ma trn kim lun K
cng xut sc, ma trn l mch trn tn hiu chi Y vo cc tn hiu mu R-Y, B-Y,
G-Y l cc tn hiu mu thiu chi to tn hiu mu y l R, G, B. Mch K
cng xut sc , khuch i ba tn hiu R, G, B ln bin ln cung cp cho n
hnh, trong qu trnh khuch i tn hiu sc, mch K cng xut sc kim lun vic
xa tia qut ngc.
Khi ng ting: L tch tn hiu FM ra khi tn hiu Video tng hp, sau
khuch i trung tn ting v tch song iu tn ly ra tn hiu m tn, tip tc
khuch i tn hiu m tn qua mch cng xut ri a ra loa.
Mch vi x l: L to ra cc in p iu khin ton b cc hot ng ca my
nh: iu khin tt m ngun t xa, iu khin thay i sang, tng phn,
mu sc ca nh, iu khin thay i qu trnh d knh v nh knh
n hnh mu: l linh kin chim ti 50% gi thnh ca Tivi, n hnh mu c
nhim v ti to li hnh nh ban u.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

3.2.2 My vi tnh
1.S my vi tnh

Hnh 3.3: S my vi tnh


2. Chc nng
CPU: c th c xem nh no b, mt trong nhng phn t ct li nht ca my
vi tnh .
Nhim v chnh ca CPU l x l cc chng trnh vi tnh v d kin.
CPU c nhiu kiu dng khc nhau. hnh thc n gin nht, CPU l mt con chp
vi vi chc chn. Phc tp hn, CPU c rp sn trong cc b mch vi hng trm
con chp khc.
CPU l mt mch x l d liu theo chng trnh c thit lp trc. N l mt
mch tch hp phc tp gm hng triu transistor.
RAM: l ni h iu hnh,ng dng lu tr data CPU c th nhanh chng truy
xut. Tng dung lng RAM ng ngha vi vic gim s ln CPU phi ly d liu
t Hard Disk, mt qu trnh mt nhiu thi gian hn c d liu trc tip t RAM.
(Thi gian truy xut RAM c tnh = ns trong khi thi gian truy xut HD c
tnh = milis).
My tnh c nhn cn 1 lng RAM nht nh cho mi ng dng,cng nhiu ng
dng bn m, lng RAM cn dung cng nhiu. Vy iu g s xy ra khi RAM y.
Rt may l h iu hnh ca chng ta c thit k x l trng hp ny. Khi
RAM gn y h iu hnh s ly bt 1 phn d liu t RAM v ghi vo cng,
thng l phn t c dung nht. Phn HD dung ghi d liu tm thi ny c
gi l PAGE FILE hay SWAP FILE dch sang ting vit c ngha l Tp tin tro
i.RAM ca chng ta v th s khng bao gi b y nhng ci gi phi tr s l
vic h thng hot ng ch v CPU phi ly qu nhiu d liu t cng.
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

Card Video: L thit b hin th thng tin ca my tnh gip ngi s dng giao
tip vi my. rng c tnh bng Inch. Mn hnh ng phng in t CRT (li,
phng) mn hnh tinh th lng LCD, mn hnh Plasma.
a cng: hay cn gi l cng (Hard Disk Drive, HDD) l thit b dng
lu tr d liu trn b mt cc tm a hnh trn ph vt liu t tnh.
L loi b nh khng thay i (non-volatile), c ngha l chng khng b mt d
liu khi ngng cung cp ngun in cho chng.
L thit b rt quan trng trong h thng bi chng cha d liu thnh qu ca mt
qu trnh lm vic ca nhng ngi s dng my tnh. Nhng s h hng ca cc
thit b khc trong h thng my tnh c th sa cha hoc thay th c, nhng d
liu b mt do yu t h hng phn cng thng rt kh ly li c.
Card Net: hay l NIC Card (Adapter Card) l thit b ni kt gia my tnh v
cp mng. Chng thng c giao tip vi my tnh qua cc khe cm nh: ISA,
PCI hay USB Phn giao tip vi mng thng thng theo cc tiu chun nh:
AUI, BNC, UTP,
- Chun b d liu a ln mng: trc khi a ln mng, d liu phi c chuyn
t dng byte, bit sang tn hiu in c th truyn trn cp.
- Gi d liu n my tnh khc.
- Kim sot lung d liu gia my tnh v h thng cp.
Card Sound: (bo mch m thanh) trong my tnh l mt bo mch m rng cc
chc nng v m thanh (v mt s chc nng khc v gii tr, kt ni...) trn my
tnh, thng qua cc phn mm n cho php ghi li m thanh (u vo) hoc trch xut
m thanh (u ra) thng qua cc thit b chuyn dng khc. Mi hot ng ca bo
mch m thanh phi c iu khin bng phn mm hoc
trnh iu khin
(driver) trn my tnh. Cc hot ng ca bo mch m thanh c th l:
- Trch xut cc tn hiu m thanh dng tn hiu tng t (analog) hoc tn hiu s
(digital) ti cc loa pht ra m thanh m con ngi nghe c.
- Ghi li v m thanh lu tr (hoc phc v x l) m thanh trong: ting ni, m
thanh t nhin, m nhc, phim...thng qua cc ng u vo.
- X l v pht li m thanh t cc thit b khc: Pht m thanh trc tip t cc a
quang, thit b pht MIDI.
- Kt ni vi cc b iu khin game (joytick).
- L thit b kt ni trung gian: (Cng IEEE-1394).
Keyboard: (bn phm) l thit b nhp. Ngoi nhng chc nng c bn, bn c
th tm thy nhng loi bn phm c nhiu chc nng m rng nghe nhc, truy
cp Internet, hoc chi game. Bn phm cm cng PS/2, bn phm cm cng USB,
bn phm khng dy.
SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

Mouse: (chut) l thit b nhp, c bit hu ch i vi cc ng dng ha.


Chut c dng bi ln xc nh v tr, chut quang dng phn ng nh sng.
Bios: (Basic Input/Output System) l h thng xut nhp c bn. Bios nm bn
trong my tnh c nhn, trn bo mch chnh. Bios c xem nh l chng trnh
c chy u tin khi my tnh khi ng. Chc nng chnh ca Bios l chun b
cho my tnh cc chng trnh phn mm c lu tr trn cc thit b lu tr
(chng hn nh cng, a mm v a CD) c th c np, thc thi v iu khin
my tnh. Qu trnh ny gi l khi ng.Thut ng ny xut hin ln u trong h
iu hnh CP/M, l phn CP/M c ti ln trong sut qu trnh khi ng, tng
tc trc tip vi phn cng (cc my CP/M thng c duy nht mt trnh khi ng
trong ROM). Cc phin bn ni ting ca DOS c mt tp tin gi l
"IBMBIO.COM" hay "IO.SYS" c chng nng ging nh BIOS CP/M. Tuy nhin,
thut ng BIOS ngy nay ch mt chng trnh phn mm khc c cha trong cc
chip c sn trn bn mch chnh nh PROM, EPROM v n nm gi cc chc nng
chun b cho my ng thi tm ra nh cng nh lin lc v giao s iu hnh my
li cho h iu hnh. BIOS cng l b phn chun ca my tnh. Mt my tnh c th
thiu mn hnh, bn phm, chut, cng, ... nhng khng th thiu BIOS.
3.3 Nhng cng vic hng ngy.
- Sa cha cc thit b.
- Kim tra li v khc phc li.
- Thay th cc thit b linh kin b hng.
3.4 Kinh nghim thc tin
- Hc hi thm c nhiu kinh nghim trong giao tip, ng x khi lm vic c
quan.
- Nhn bit c kh nng, nng lc lm vic ca bn thn.
- To c vn kin thc nht nh p dng cho cng vic sau ny.
- X l tnh hung nhanh, thao tc s dng cc thit b cn chnh xc.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

LI KT
Truyn hnh cp l mt c th ring bit do n chim mt v tr rt quan
trng trong i sng ca ngi dn Vit nam ni ring v tt c mi ngi dn trn
ton th gii ni chung. V th hin nay Truyn hnh c coi nh l mt tri tim, l
mt lnh vc truyn thng c th p ng tt c mi nhu cu xem truyn hnh ca
mi ngi vi danh hiu mang c th gii n ngi nh ca bn.
Tm li truyn hnh cp l mt knh thng tin khng th thiu trong i sng
ca mi ngi.
Mt ln na em xin chn thnh cm Thy gio Nguyn C Vn Thanh v cc
thy c trong khoa k thut ca trng C PT-THI, cn b Cng Ty C Phn in
T Tin Hc HEREVN v c bit l anh Trnh Ngc Thoi ph phng k thut
truyn dn pht sng gip , ch bo tn tnh cho em v gip em hon thnh tt
bi bo co ny!
Em xin chn thnh cm n!
H Nam, thng 04 nm 2013
Sinh vin
Nguyn Xun V

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

TI LIU THAM KHO


-

Gio trnh k thut truyn hnh.


Gio trnh truyn hnh cp Vit Nam.
http://tailieu.vn/
http://vctv.vn/
Nhiu ngun ti liu khc.

SV: Nguyn xun V

Lp TVT 7A

Bo co thc tp tt nghip

Mng Vin Thng

MC MC

SV: Nguyn xun V

Lp TVT 7A

You might also like