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Dang Ky Vi Tri, PHTS Quoc Te_BKHN-LB
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H NI, 4/2015
TH TC NG K TN S, QU
O V TINH A TNH V PHI
HP TN S QUC T
Ni dung
1. Gii thiu v Lin minh Vin thng quc t ITU
2. Quy hoch bng tn nghip v v tinh
3. Cc quy nh ca ITU i vi nghip v v tinh
4. Cc th tc ng k v tr qu o v tinh a tnh
5. Tnh ton ng truyn (link budget)
6. Phi hp tn s, qu o v tinh tnh ton can nhiu
7. Chuyn : VINASAT
Gii thiu v ITU
Tng quan
Nhim v
M hnh t chc
ITU International Telecommunications Union l mt t chc c bit ca UN, lin quan n s pht trin ton
cu ca mng vin thng v cc nghip v v tuyn in.
c thnh lp ngy 17/5/1865
193 nc thnh vin v trn 700 hi vin, hc vin
Gm 750 nhn vin vi 100 quc tch khc nhau
C tr s ti thnh ph Geneva, Thy S
Website: http://www.itu.int
Nhim v ca ITU bao gm cc lnh vc v k thut, pht
trin v chnh sch.
C th:
y mnh s pht trin v khai thc hiu qu cc
ngun ti nguyn vin thng (ITU-R, ITU-T).
y mnh v tr gip cc nc pht trin trong lnh
vc vin thng (ITU-D).
Thc y cch tip cn rng v cc vn trong x
hi v kinh t thng tin.
HI NGH TON QUYN
y ban phi hp SG, DSG, Gim c
Ban th k (Tng th kl)
(Ph tng th k)
HI NG ITU
TNG TH K PH TNG TH K
Hi ng t vn vin thng th gii
y ban Pht trin Vin thng
ITU-D (Gim c)
y ban Thng tin v tuyn
ITU-R (Gim c)
y ban Tiu chun ha
Vin thng ITU-T
(Gim c)
PHI HP
CH O
T VN
T CHC CA ITU
T CHC CA ITU-R
Gii quyt cc s v
gia 2 k WRC
Gim st vic thc thi Th l
Bu ra SG chair
Nhim v ca ITU-R:
m bo ngun ti nguyn ph tn s, qu
o v tinh c s dng mt cch hp l,
cng bng, hiu qu v kinh t theo iu 44
ca Hin chng ITU;
Nghin cu v ph chun cc quy nh,
khuyn ngh lin quan n lnh vc tn s v
tuyn in v qu o v tinh.
Cc quy nh ca ITU-R - khung php l cc quc
gia, t chc quc t tun th trong ng k v khai
thc tn s v tuyn in v qu o v tinh :
- Th l v tuyn in Radio Regulations;
- Ph lc Appendix;
- Ngh quyt Resolution;
- Khuyn ngh - Recommendations: a ra cc tiu chun
k thut nhm khuyn ngh cc quc gia, t chc khai thc
v tinh s dng.
Cc quy nh trn c Hi ngh thng tin v tuyn th
gii (WRC) ph chun -> ITU ban hnh
Quy hoch tn s
Tng quan
Bng tn v tinh
- Nhm phn b cc bng tn s cho cc nghip v v tuyn khc nhau;
- Nhm s dng hiu qu ngun ti nguyn tn s, trnh can nhiu gia cc nghip v v tuyn;
- Lin minh Vin thng quc t ITU l c quan c trch nhim nghin cu v ban hnh Quy hoch tn s v tuyn in (iu 5, Th l VT) sau khi c Hi ngh Thng tin v tuyn th gii WRC ph chun;
- Mi quc gia cn c trn quy hoch tn s quc t ca ITU, nghin cu v ban hnh Quy hoch tn s cho quc gia mnh Quy hoch ph tn s quc gia;
- ITU chia th gii thnh 3 khu vc, mi khu vc c th c
Quy hoch tn s khc nhau;
- Ch vit hoa l NGHIP V CHNH;
- Ch vit thng l Nghip v ph;
- Nghip v ph khng c gy can nhiu cho Nghip v
chnh v khng c khng ngh nhiu t Nghip v chnh;
- Cc s v ch pha cui l cc ghi ch (Vit Nam c ghi
ch thm ca quc gia)
5.432B Different category of service: in Bangladesh, China, French overseas communities of Region 3, India, Iran (Islamic Republic of), New Zealand and Singapore, the band 3 400-3 500 MHz is allocated to the mobile, except aeronautical mobile, service on a primary basis, subject to agreement obtained under No. 9.21 with other administrations and is identified for International Mobile Telecommunications (IMT).
VTN16 Cc bng tn s sau c u tin s dng cho cc h thng hot ng trong nghip v C nh qua v tinh:
3 400-3 700 MHz (chiu t v tr ti tri t)
6 425-6 725 MHz (chiu t tri t ti v tr)
10 700-11 700 MHz (chiu t v tr ti tri t)
12 750-13 250 MHz (chiu t tri t ti v tr)
13 750- 14 000 MHz (chiu t tri t ti v tr)
14 250-14 500 MHz (chiu t tri t ti v tr)
Cc h thng thuc nghip v C nh qua v tinh nm trong cc
bng tn xung nu trn (chiu t v tr ti tri t) phi c b lc thu
t tiu chun v lc cc tn hiu ngoi bng.
Cc h thng thuc cc nghip v khc hot ng trong bng tn ny
khng c gy nhiu c hi cho cc h thng thuc nghip v C nh
qua v tinh v khng c khng ngh nhiu i vi cc h thng C
nh qua v tinh.
MT S NGHIP V V TINH
FSS Fixed Satellite Service: C nh qua v tinh
BSS Broadcast Satellite Service: Qung b qua v tinh
MSS Mobile Satellite Service: Di ng qua v tinh
EESS Earth Exploration Satellite Serive - VNREDSAT
AP30/30A/30B: Bng tn thuc Ph lc 30 ca Th l v
tuyn ca ITU Nhm m bo cho cc nc trn th gii
u c v tr qu o, tn s phng v tinh, tuy nhin, vng
dch v v tinh b gii hn trong lnh th quc gia , mun
cung cp dch v sang lnh th quc gia khc, cn phi t
c tha thun vi quc gia .
Bng tn Uplink Downlink Ghi ch
C 5850-6725 MHz 3400-4200 MHz Bng tn Khng quy hoch - FSS
6725-7025 MHz 4500-4800 MHz Bng tn Quy hoch AP30B - FSS
Ku
13.75-14.5 GHz 10.95-11.2 GHz
11.45-11.7 GHz
12.2-12.75 GHz
Bng tn Khng quy hoch - FSS
12.75-13.25 GHz 10.7-10.95 GHz
11.2-11.45 GHz
Bng tn Quy hoch AP30B - FSS
14.5-14.8 GHz 11.7-12.2 GHz Bng tn Quy hoch AP30/30A BSS
Ka
18.1-18.4 GHz
24.75-25.25 GHz
27-31 GHz
17.1-21.2GHz
21.4-22 GHz
Bng tn Khng quy hoch - FSS
17.3-18.1 GHz Bng tn Quy hoch Feeder link cho
nghip v BSS thuc Ph lc 30A
MT S BNG TN CHO CC NGHIP V V TINH
Cc quy nh ca ITU
Mc ch:
-m bo nghip v v tinh khng gy nhiu cho cc
nghip v v tuyn khc;
- a ra cc tiu chun xc nh cc mng v tinh cn
phi hp can nhiu
1. Gii hn pht x trm mt t (iu 21)
2. Gii hn pht x trm khng gian (iu 21)
3. Gii hn lch trc anten trm mt t (Rec ITU-R S.580, Appendix 8))
Antenna sidelobe will conform to 29 25log ();
4. The up-link off-axis EIRP density of all carriers shall not exceed the limits specified in Recommendation ITU-R S.524-7
- GSO networks in the FSS operating in the 6 GHz frequency band be designed in such a manner that at any angle, , which is 2.5 or more off the main lobe axis of an earth station antenna, the e.i.r.p. density in any direction within 3 of the GSO should not exceed the following values: Angle off-axis Maximum e.i.r.p. per 4 kHz 2.5 < 48 (35 25 log ) dB(W/4 kHz) 48 180 7 dB(W/4 kHz); - Earth stations operating in GSO networks in the FSS operating in the 12.75-13.25 GHz and 13.75-14.5 GHz frequency bands be designed in such a manner that at any angle, , which is 2.5 or more off the main lobe axis of an earth station antenna, the e.i.r.p. density in any direction within 3 of the GSO should not exceed the following values: Angle off-axis Maximum e.i.r.p. per 40 kHz 2.5 7 (39 25 log ) dB(W/40 kHz) 7 < 9.2 18 dB(W/40 kHz) 9.2 < 48 (42 25 log ) dB(W/40 kHz) 48 < 180 0 dB(W/40 kHz). For any direction in the region outside 3 of the GSO, the above limits may be exceeded by no more than 3 dB;
5. Tiu ch xc nh mng v tinh cn phi hp can nhiu
5.1. Quy nh v cung qu o phi hp
Im/N0 = T /T 6% (Gi tr ngng) mng v tinh A c th gy nhiu cho mng v tinh B
Mng v tinh B Mng v tinh A
p
Gt
Gr
T
L
Im = (p Gt Gr ) / L V: Im = K T
nn, T = Im / K T / T = Im / KT T / T = (p Gt Gr )/KLT
Im l mt cng sut nhiu ti u ra ca anten thu trm mt t b nhiu
5.2. Ch tiu ngng xc nh can nhiu hai mng v tinh
Cc th tc ng k v tr qu o v
tinh a tnh vi ITU
Mc ch
Cc th tc php l
Cc mc thi gian ca mt h s v tinh
Mc ch:
o c th ng k thnh cng mt v tr qu o v
tinh;
o m bo v tinh hot ng hp php trong khun kh
quy nh ca ITU, khng can nhiu.
Th tc php l: gm 3 bc
- Np b h s s b- API (Advance Publication Information)
- Np b h s phi hp CR/C (Coordination Request)
- Np b h s Thng bo - Notification
H s s b - API: nhm thng bo vi quc t v d n v tinh mi ca 1 quc gia: v tr qu o, bng tn.
Lu : Ngy ITU nhn b h s ny c tnh l ngy hiu lc ca b h s v tinh vi thi hn hiu lc l 7 nm.
H s phi hp CR/C (c ph x l h s): cung cp cc thng s chi tit v d n v tinh nh: v tr qu o, vng ph sng, tn s hot ng, bng thng b pht p, kiu sng mang, cng sut pht, yu cu bo v, c im ca trm mt t. (Ngy ITU nhn b h s ny c tnh l ngy u tin ca mt h s v tinh)
Sau khi np b h s ny, ITU-R s xut bn danh sch cc mng v tinh b nh hng (theo tiu ch cung qu o phi hp v T/T). Quc gia ng k mi s tin hnh phi hp tn s v tinh vi cc nc b nh hng m bo d n v tinh mi khng gy can nhiu cho cc mng v tinh ng k trc. Qu trnh ny ko di nhiu nm.
Thng bo - Notification (c ph x l h s): Da trn kt qu phi hp, quc gia ng k h s v tinh mi thng bo vi ITU c im cui cng ca v tinh ITU ghi vo c s d liu quc t (MIFR Master International Frequency Register), t h thng v tinh mi s c ITU bo v can nhiu quc t.
28
V d v h s API?
29
V d v b h s CR/C
30
V d v b h s Notification
PART I-S: ITU-R nhn v ang x l; PART II-S: ITU-R xc nhn mng h s v tinh hon thnh cc th tc ITU; PART III-S: gi li cho quc gia s hu yu cu b sung thm cc thng s, thng tin ITU-R tip tc x l
Cc mc thi gian cho mt h s v tinh
Khong thi gian 6 thng gia ngy np API v CR/C?
24 thng l thi hn phi np CR/C?
90 ngy 6 thng c ngha g?
3 nm suspension c ngha g?
Ti sao cn c thi hn cho b h s v tinh?
Nu cc mc thi gian khng c tun th => ???
V tinh khng th a vo s dng trc thi hn quy nh => ???
Lm th no ITU bit v tinh ca mt quc gia c a vo s dng? Resolution 49
Cha th hon thnh phi hp tn s, c c phng v khai thc v tinh hay ko?
Nhng cch lch lut:
o Khai bo bng tn m thc s v tinh khng c/ko s dng.
o S dng mt v tinh khai bo a vo s dng nhiu
v tr qu o khc nhau -> s hu nhiu v tr qu o.
Cc tnh hung
Vit Nam v VNPT trnh cc b h s v tinh VINASAT t nm 1996;
Vit Nam v VNPT mt hn 10 nm hon thnh phi hp tn s vi cc nc b nh hng nh Nht Bn, Trung
Quc, Tonga, Nga, Thi Lan
Sau khi v tinh ln qu o, vic thc hin cc th tc php l vi ITU vn tip tc c thc hin m bo v tinh
VINASAT khng b can nhiu bi cc nghip v v tuyn khc,
t cc v tinh ng k mi khc.
Vit Nam v VNPT c nhn lc v kinh nghim thc hin tt cc th tc php l vi ITU.
Qu trnh phi hp tn s cho VINASAT-1/-2
Mun c v tr qu o cn phi thc hin cc th tc php l vi Lin minh Vin thng quc t ITU ITU u tin x l theo
nguyn tc First come, First serve.
Cn phi thc hin cng tc phi hp tn s, qu o v tinh vi cc v tinh b nh hng m bo v tinh hot ng khng
can nhiu;
Mi h s v tinh u c thi hn v s b ht hn nu khng a v tinh vo s dng;
H s VINASAT c gi ln ITU t nm 2006. Qu trnh phi hp tn s cho VINASAT ko di hn 10 nm.
Bn cnh k nng v k thut v tinh, cn phi hiu v vn dng hiu qu th tc php l quc t trong ng k qu o,
khai thc v tinh, x l can nhiu.
Tng kt
Tnh ton ng truyn-link budget
L qu trnh tnh ton mc cng sut pht t trm mt t v v tinh m bo ch s C/N yu cu ti my thu;
Mc cng sut pht ph thuc vo kiu dch v, iu ch, m ha , v tr trm mt t v tham s v tinh;
Cn ti u ha cng sut pht trm mt t, ng knh anten, bng thng ti thiu ha gi thnh;
Tnh ton ng truyn-link budget
Symbol Description Unit
P TE Earth Station Transmit Power dBW
G TE Antenna Transmit Gain dBi
G RS Satellite Receive Gain dBi
N OS Satellite Receive Noise Power Density dBW/Hz
G S Gain of the Satellite dB
P TS Satellite Transmit Power dBW
G TS Satellite Transmit Gain dBi
G RE Earth Station Receive Gain dBi
N OE Earth Station Receive Noise Power Density dBW/Hz
TYPICAL SATELLITE COMMUNICATIONS LINK
SATELLITE
TRANSMIT EARTH STATION RECEIVE EARTH STATION
P T E
G T E
G R S
N O S G
S
P T S
G T S
G R E
N O E
Tnh ton ng truyn-link budget
1. C/N uplink (ko gian t do)
2. C/N Downlink (ko gian t do)
3. C/(N+I) Total
),log(10),log(106.228
/
0 HzBKTN
LGGPC
NCNC
ES
RESTS
DL
)],log(106.228[)/(C/N
),log(10),log(106.228..
/
UP
0
HzBLTGGP
HzBKTBTkN
LGGPC
NCNC
STETE
S
STETE
UL
dBN
CDLNCULNC
total
),1010log(10 10/
10
/
Tnh ton ng truyn-link budget
1. Cc tham s u vo:
Tc truyn;
iu ch: 8PSK => ch s iu ch M=3; m ha FEC; ch s roll-off; Reed-Solomon(R/S);
Occupied BW = BR*(1+Roll-off)* R/S /(M*FEC)
r: bn knh tri t-6378.14km;
S: bn knh qu o a tnh 42164.57km
eslat: v trm mt t (N);
eslong: kinh trm mt t (E);
satlong v tr qu o v tinh (E)
Ch s cht lng v tinh G/T (dB/K)
Tnh ton ng truyn-link budget
2. Tnh ton cc tham s lin quan
Khong cch t trm mt t n v tinh
d=sqrt(r^2+S^2-2.r.S.cos(eslat).cos(longdiff))
longdiff= satlong- eslong
Suy hao ko gian t do: L = 32.4+10log(d, km)+10log(f, MHz)
Tng ch anten trm mt t: Gain max(dBi) = 10*log[*(pi*D/)2]
Where: - antenna efficiency, typical value: 0.65 pi=3.14 D - antenna size, m - wavelengh, m vi = 1/frequency(Hz)
Tnh ton ng truyn-link budget
2. Yu cu
M = C/N tnh ton c C/N req
M 2 dB (in hnh)=> tuyn thng tin hot ng bnh
thng
)(
)/(
/ 0
MHzBW
sMbBRN
E
NC
b
req
Thng s Eb/No vi mt s loi iu ch v m FEC (Ngun: Assumes 188/204 Reed-Solomon and Roll-off factor per ETSI EN 301 210)
Modulation FEC Eb/N0 (dB)
8PSK
0.95 9.9
7/8 6.8
3/4 6.0
2/3 4.4
2/3 6.0 with Reed Solomon
QPSK
1/2 2.8
2/3 2.5
3/4 4.0
0.95 6.5
7/8 4.2
8-QAM 2/3 4.4
3/4 5.0
16-QAM
3/4 7.7
7/8 7.9
3/4 8 with Reed Solomon
7/8 9.5 with Reed Solomon
Tnh ton can nhiu v tinh
Tnh ton t s C/I v C/I margin Uplink case Downlink case
Gii hn can nhiu theo quy nh ca ITU
Phi hp tn s v tinh
Tnh ton trng hp c th
Tnh ton t s C/I v C/I margin
M hnh can nhiu
g'SAT
p'SAT
GES ( )
a
a
a
+ a
a
+ a
Wanted
satellite
Interfering
satellite
Wanted
transmitting
earth station
Wanted receiving
earth station
Interfering
earth station
p'ES
EIRP SAT
g'ES ( )
EIRP ES gmax ES
g SAT-ES wanted g SAT-ES int
is the topocentric
angle between the two
satellites
1.1 x g
where g is the
geocentric angle
between the two
satellites
(C/I) = EIRPES, wanted+GSAT-ES wanted(P'ES int+G'ES int( )+GSAT-ES int ) - A + Y
EIRPES wanted EIRP trm mt t ca v tinh mong mun(dBW or dBW/Hz)
GSAT-ES wanted Tng ch anten v tinh hng v trm ES mong mun (dBi)
P'ES Cng sut trm mt t gy nhiu(dBW or dBW/Hz)
G'ES () Tng ch trm ES gy nhiu hng v v tinh mong mun(dBi)
GSAT-ES int Tng ch anten v tinh mong mun hng v trm ES gy nhiu (dBi)
A Hiu suy hao ko gian t do gia 2 tuyn: gy nhiu v mong mun(dB)
Y Gi tr phn cch phn cc gia 2 tn hiu nhiu v mong mun(dB)
44
T s C/I cho ng ln v tinh (Rec. ITU-R S.740)
(C/I) = (EIRPES, wanted EIRP'ES, int( ))+(GSAT-ES wantedGSAT-ES int ) or
(C/I) = DEIRPES+DGSAT wanted
EIRPES wanted EIRP ca trm ES mong mun EIRP'ES int EIRP ca trm ES gy nhiu hng v v tinh mong mun
GSAT-ES wanted Tng ch anten v tinh mong mun hng v trm ES mong mun
GSAT-ES int Tng ch anten v tinh mong mun hng v trm ES gy nhiu
Vi gi thit A v Y bng 0.
45
Cng thc rt gn tnh C/I ng ln
Gain max(dBi) = 10*log[*(pi*D/)2] Where: - antenna efficiency, typical value: 0.65
pi=3.14
D - antenna size, m
- wavelengh, m vi = 1/frequency(Hz)
Tng ch anten lch trc ca trm ES (khuyn ngh ITU-R S.580 hoc Ph lc 8 ca Th l v tuyn in ca ITU)
Typically G(off-axis) = 29-25*log(topocentric angle)
For example: separation angle = 3.5 degree => off-axis angle = 1.1 x 3.5 = 3.85 deg
G(off-axis) = 29-25*log(3.85) = 14.4 dBi
46
Tng ch anten trm mt t ES
(C/I) = EIRPSAT wanted + Gmax ES wanted (P'SAT int+G'SAT int+GES wanted ( )) - A + Y
EIRPSAT wanted EIRP ca v tinh mong mun(dBW or dBW/Hz)
Gmax ES wanted Tng ch anten trm ES mong mun (dBi)
P'SAT int Cng sut v tinh gy nhiu (dBW or dBW/Hz)
G'SAT int Tng ch anten v tinh hng v trm ES mong mun (dBi)
GES wanted () tng ch anten trm ES mong mun theo hng v v tinh gy nhiu (dBi)
A Hiu suy hao ko gian t do gia 2 tuyn: mong mun v gy nhiu(dB)
Y cch ly phn cc gia 2 tuyn: mong mun v gy nhiu (dB)
47
Tnh t s C/I cho ng xung(Rec. ITU-R S.740)
(C/I) = (EIRPSAT wanted EIRP'SAT int) + (Gmax ES wanted GES wanted ( ))
or
(C/I) = DEIRPSAT + DGES wanted
EIRPSAT wanted EIRP ca v tinh mong mun (dBW or dBW/Hz)
EIRP'SAT int EIRP ca v tinh gy nhiu (dBW or dBW/Hz)
Gmax ES wanted tng ch trm ES mong mun(dBi)
GES wanted () tng ch trm ES hng v v tinh gy nhiu (dBi)
assuming A and Y are equal to zero.
48
Cng thc rt gn tnh C/I cho ng xung
(c/i)-1total = (c/i)-1 + (c/i)
-1
where the ratios are computed in their natural (not dB) form (use 10log() to obtain the value in dB).
49
T s C/I tng cng
dBI
CDLICULIC
total
),1010log(10 10/
10
/
Gi tr C/I ngng
Sng mang mong
mun
Sng mang nhiu T s C/I ngng yu cu
(dB)
TV-FM TV-FM or digital (C/N)req + 14
Digital Digital (C/N)req + 12.2
50
Gi tr C/N yu cu in hnh cho sng mang s l 8-10dB, do t s C/I ngng yu cu l 20-22dB (ty theo yu cu ca sng mang c th, ch s C/I c th tng thm, v d sng mang Lnh, iu khin v o xa TTC c th yu cu 26dB). Cu hi: gi tr (C/N)req c tnh nh th no??? Cn tnh n iu ch, m ha, tc truyn, ch s roll-off
Tnh ton gi tr C/I margin
C/I margin is : M = (C/I)produced (C/I)req
If M 0 : khng c can nhiu;
If M < 0: c can nhiu xy ra.
51
Cc gii php hn ch, loi tr can nhiu v tinh
Gim cng sut pht;
Tng kch thc anten trm mt t;
Gim C/N yu cu ca sng mang;
cch ly qu o thch hp;
S dng bng tn khc nhau, phn cc khc nhau
Cch ly vng ph;
Trng hp kh nht: cng tn s, cng vng ph, cch ly qu o nh (< 2 ) thng nht s dng dch v trn 2 v
tinh m bo ko gy can nhiu cho nhau
V d: v tinh 1 s dng tn s F1, vng ph A: cung cp dch v VSAT th
v tinh 2 nu mun s dng tn s F1, vng ph A th bt buc phi cung
cp dch v DTV
52
Mc ch: mng v tinh mi khng gy can nhiu cho mng v tinh i trc;
u ni vi quc gia/nh khai thc v tinh b nh hng t chc cuc hp phi hp tn s;
Nghin cu cc h s v tinh lin quan;
Tnh ton cc mc can nhiu ln nhau;
Cn c trn ch tiu k thut v tinh; thng s khai thc ca khch hng => chp thun mc cng sut pht ng ln, ng
xung ph hp;
K kt bin bn phi hp;
Thng bo cho ITU kt qu phi hp.
Qu trnh phi hp v tinh thng ko di nhiu nm
Qu trnh phi hp tn s cho v tinh
BI TP Tnh ton can nhiu t XSAT-1 vo VINASAT
Thng s v tinh v sng mang ca VINASAT
V tr qu o: 131.94 E
Station keeping: 0.04
G/T v tinh: coutour v tinh km theo
Sng mang: iu ch: 8 PSK, FEC: , no Reed Solomon. Tc truyn: 31.3 MB/s
Phn pht: v tr pht: H Ni (105.67N, 21.02E)
o Tn s pht: 13027 MHz. Tn s thu: 11222 MHz
o Anten pht: kch thc 9m, hiu sut anten: 65%
o Cng sut pht ln: 1.7W
Phn thu: v tr thu: gin khoan ngoi khi Vng Tu (108.02N- 9.52E)
o Anten thu 0.6m, hiu sut anten: 65%
o EIRP pht ca v tinh: 46.6 dBW
o Nhit tp m thu: 75 K
54
BI TP Tnh ton can nhiu t XSAT-1 vo VINASAT
Thng s v tinh v sng mang ca XSAT-1
V tr qu o: 129 E
Station keeping: 0.04
G/T v tinh: coutour v tinh km theo
Sng mang: iu ch: 8 PSK, FEC: , no Reed Solomon. Tc truyn: 15.6 MB/s
Phn pht: v tr pht: Vin Chn (102.75N 18E)
o Tn s pht: 13027 MHz. Tn s thu: 11222 MHz
o Anten pht: kch thc 1.8m, hiu sut anten: 65%
o Cng sut pht ln: 22.6W
Phn thu: v tr thu: H Ni (105.83N 21.03E)
o Anten thu 0.6m, hiu sut anten: 65%
o EIRP pht ca v tinh: 46 dBW
o Nhit tp m thu: 75 K
55
56
G/T contour ca VINASAT, dB/K
57
G/T contour ca XSAT-1
Gi tr G/T ti cc ng contour: en: -2 dB/K. Xanh l cy m: -4 dB/K. Hng: -6 dB/K. : -10dB/K. Xanh da tri -15dB/K
58
Yu cu ca bi tp
Tnh t s C/I trong trng hp xu nht cho ng ln v ng xung ti u thu ca v tinh VINASAT do tn hiu t h thng v tinh XSAT-1 gy ra, sau so snh vi gi tr ngng t rt ra kt lun liu h thng v tinh LAOSAT-1 c gy can nhiu cho VINASAT hay ko? (Lu : kt lun nhiu ring r cho ng ln v ng xung):
Tnh ton c chnh lch v tr qu o ca 2 v tinh;
Tnh c tng ch cc i anten trm mt t thu v pht ca VINASAT v tng ch anten thu/pht theo hng v tinh LAOSAT-1;
Tnh c tng ch cc i anten trm mt t thu v pht ca LAOSAT-1 v tng ch anten thu/pht theo hng v tinh VINASAT;
Tnh c chnh lch tng ch anten v tinh gia 2 v tinh;
Tnh c t s C/N yu cu t tnh c t s bo v C/I yu cu i vi sng mang ca v tinh VINASAT;
Tnh c t s C/I ti u thu ca VINASAT (ng ln, ng xung);
So snh vi mc ngng v kt lun liu c can nhiu hay ko?
Nu c nhiu, a ra cc bin php u tin loi can nhiu.
59
Mt s lu
Tnh C/I trong t/h gi thit cng phn cc;
Do cc sng mang ca 2 v tinh c bng thng khc nhau do , thc hin php tnh chnh xc hn, cng bng hn, thng thng s dng khi nim mt cng sut, tc gi tr cng sut trn ton b bng thng ca sng mang, n v l dBW/Hz. V d: P=2W=3dBW, BW=2 MHz => Power density (PSD)= -60dBW/Hz;
Tng ch anten trm mt t theo gc lch so vi trc chnh c tnh theo cng thc ti Ph lc trang sau;
thun tin hn trong tnh ton, s dng n v dB.
60
Cng tc tnh gi tr tng ch anten E/S ti cc gc lch trc
a. Nu D/ 100 (maximum gain 48 dBi)
00
0
1
2
3
max
18048for 10)(
48for )log(2529)(
for )(
0for 105.2)(
G
G
GG
DGG
r
rm
m
Trong :
D: bn knh anten, m.
: bc sng, m.
: gc lch so vi trc chnh anten, .
G1 : tng ch ti sidelobe th nht = 2+15log(D/)
61
b. Nu D/ < 100 (maximum gain < 48 dBi)
00
0
1
2
3
max
18048for log10 10)(
48100for )log(25log1052)(
100for )(
0for 105.2)(
DG
D
DG
DGG
DGG
m
m
degree ,85.15
degree ,20
6.0
r
1max
D
GGD
m
62
Hi / p
Phi Trng Hp
Vietnam Posts and Telecommunications Group (VNPT)
Email: Hoppt@vnpt.vn; Hop.phitrong@gmail.com . Cell: 090.4.160.860
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