Dang Ky Vi Tri, PHTS Quoc Te_BKHN-LB

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)


13 750- 14 000 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;


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


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

/


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)


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)


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

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56

G/T contour ca VINASAT, dB/K

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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.

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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.

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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/)

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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

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Hi / p

Phi Trng Hp

Vietnam Posts and Telecommunications Group (VNPT)

Email: [email protected]; [email protected] . Cell: 090.4.160.860

Dang Ky Vi Tri, PHTS Quoc Te_BKHN-LB

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