bai tap 4-thong tin ve tinh

8/8/2019 bai tap 4-thong tin ve tinh

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Link BudgetCalculation


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Introduction

A satellite communication link is definedas an Earth station - satellite - Earthstation connection.

The Earth station - satellite segment iscalled the uplink.

The satellite - Earth station segment iscalled the downlink.


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Introduction

The Earth station design consists of theTransmission Link Design (Link Budget)and the Transmission System Design.

Link Budgetestablishes the resourcesneeded for a given service to achieve the

performance objectives.


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Bi tp 4

Link Budget Calculation betweenthe VINASAT satellite andthe Earth Station at H Ni


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Link Parameters

*Operation Bandwidth

Link design at Ku-Band, using frequencyof 14GHz for the uplink and 11GHz forthe downlink.


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Link Parameters

*Earth Station

- Located at 210N latitude and 105,450Elongitude.

- The diameter of the antenna (D) is 10m, theaperture efficiency () is 70%- Transmission power of Earth Station is 50W.

- Earth station antenna height of 7m abovesea level.

- Earth station antenna height of 7m abovesea level


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Link Parameters

*Satellite

- Located at 1320E longtitude.

- (EIRP)s = 55dBW.- Transponder Bandwidth is 36MHz.

- Receiver noise figure F = 4dB.

- Receiver figure of merit(G/T)s = 8.4dB/

0K


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Link Parameters

*Other suppositions

- Feeder loss LF = 1dB

- Polarization mismatch loss LPOL

= 0.1dB

- Antenna misalignment loss 0.9dB

- Rain loss figure = 2.56dB/km, rain heighthR = 3.208Km

- Tropospheric loss figure 0.02dB/Km- Ambient temperature TX = 300

0K


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- Distance from earth to satellite is calculated

where+ Re:radius of earth Re=6378 Km

+ r: radius of satelite r=h + Re+ Latitude of earth at Ha Noi = 210 N+ Longitude of earth at Ha Noi Le = 105,450N+ Longitude of satellite Ls = 1320E

Difference in longitude between the earthstation and the satellite is :

Le = 1320 105,450 = 26.550

0 = 33.370

e0 Lcos.coscos (J!F

)cos2( 022 Fee rRRrd !

J

8351.055.26cos21coscos 000 !!F

C LI THNG TIN


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Tinh goc ngang anten trammat dat

Distance between VINASAT satellite and Earthstation at Ha Noi is

d=36986.255 km- Elevation angle of satellite from the Earth

station e

((Ch

ng minh ))

where Re = 6378 [km]

r = 42146 [km]

t = 1.24318 = 51.1870

0

e0

e sin

r

Rcos

tgF

F!U

(33.370)cos.6378.42146.2637842146 22 !d


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tnh ton tuyn ln

- Azimuth of the satellite a

A = -50.770

a = 1800 (50.770) = 230.770

- transmit antenna gain of Earth station

where = 0.7 ; D = 10m ; fU= 14GHz ; c=3.108m/s GTe = 61.7697 [dB]

225.1)21sin(

7.23

)sin(0

0

!

!

(!

tgLtgtgA e

J

2

UTe c

Dflog10G

TL!


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Uplink Budget

- Earth station transmit power (50W) in dB is

PTe = 10log(50) = 16.9897 [dBW]

- Equivalent Isotropic Radiated Power of thetransmitting Earth station is

EIRPe = GTe+ PTe - LF = 77.7594 [dBW]

- Uplink total loss isLU = LSPU + LFU + LOU


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Tinh suy hao

+ Free-space loss is

+ Rain loss is (LR)U = U.LS [dB]

where LS is the effective path length of the

signal through the rain trang 11

( Lap slide rieng )

At 210N latitude, rain height (adapted fromCCIR Recommendation 564) is

hR = 3,028 [km] ( sch cho )

hS = 7m = 0,007km ; sine = sin51.1870

L = 3.585km

[dB]206,7207)lg(20)4lg(20 !! cdfL USPU T

e

SRS sin

hhL

U

!


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He so suy hao do mua

- depend on frequency and cuong do mua- da vo bng coefficient on frequency and polarization

when f=14Ghz =0,0367, =1,154,=0,0335, =1,128

- He so suy hao do mua khi song phan cuc dung , ngang:= = = 21.57

[db/km]

= = = 17.06 [db/km]

Uplink rain loss is (LR)U= U.LS = 19.315 * 3.585 = 69.244 dB

01,pR

ha

vbhb

va

hK hb

ph Ra )(*154.1)251(*0367.0

vK

hb

pv Ra )(* 128.1)251(*0335.0

kmdbvhu ]/[315.192

06.1757.21

2!

!

!

KKK


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Uplink Budget

+ Antenna misalignment losses areLTe = 0.9dB ; LRs = 0.9dB

+ Polarization mismatch loss isLPOL = 0.1dB

+ Loss due to tropospheric

effects is

=0.385 dB

)187.51sin

15(*02.0)sin

(** !!!e

trtrtrtrtr

hlL JKK


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Uplink Budget

Hence, uplink total loss is

LU = LSPU + LFU + LOU= LSPU + (LRU + LTe + LRs + LPOL + Ltr)

= 206.7207 + (69.244 + 0.9 + 0.9 + 0.1 + 0.385)

= 278.25[dB]

- Satellite receiver noise temperature

vi F = 4dB he so tap am cua ve tinh

T0 = 2900K nhit chun

TRS

= 4380K

F

T)(T !


17/25

- Uplink noise temperature is TU = TRS +

TASwhere TRS = 438

0K ; TAS = 2900K nhit

tp m ca anten thu v tinh

TU = 4380

+ 290

0

= 728

0

K- Satellite receive antenna gain is

GRS= (G/T)S + 10lgTU [dB]

where (G/T)S = 8.4 dB/0

K GRS= 8.4 + 10lg728 = 37.02 [dB]


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Uplink Budget

- Satellite received carrier power is

CRS = EIRPe LU + GRS=

= 77.7594 - 278.25 + 37.02 = -162.5 [dBW]

- Uplink noise power is NU = 10lgkTUBwhere k is Boltzmanns constant (1,38.10-23 [J/K])

TU equivalent noise temperature (7280K)

B is the noise bandwidth of the carrier 36MHz

- Uplink carrier-to-noise ratio

(C/N)U = 77.7594 + 124.4 = 21.826 [dBW]

][4.124)10*36*728*10*38.1lg(10 623 dbWNu !!

!!! (-124.4)--162.5)/( uRSu NCNC


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Downlink budget

- Downlink total loss LD+ Free-space loss is

(Ltd

)D= 20lg(4f

Dd) 20lgc

= 20lg(4x11.109x36986.255x103)-20lg3.108

= 204.62 dB


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He so suy hao do mua

- depend on frequency and cuong do mua- da vo bng coefficient on frequency and polarization

when f=11Ghz =0,0144, =1,246=0,0128, =1,232

- He so suy hao do mua khi song phan cuc dung , ngang:= = = 14.07

[db/km]

= = =11.57[db/km]

Downlink rain loss is (LR)D= U.LS = 12.82 * 3.585 = 45.95 dB

01,pR

ha

vbhb

va

hK hb

ph Ra )(*246.1)251(*0144.0

vK

hb

pv Ra )(* 232.1)251(*0128.0

kmdbvhu ]/[82.122

57.1107.14

2!

!

!

KKK


21/25

+ Polarization mismatch loss is LPOL=0.1 dB

+ Antenna misalignment losses are

LTs = 0.9 dB ; LRe = 0.9 dB+ Loss due to troposphericeffects is

=0.385 dB

)187.51sin

15(*02.0)sin

(** !!!e

trtrtrtrtr

hlL JKK


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Downlink budget

Downlink total loss is

LD = (Ltd)D + (LR)D + Ltr + LPOL+ Lts + Lre= 204.62+45.95 + 0.385+ 0.1 +0.9 + 0.9

= 252.85 dB

- Earth station receive antenna gain is

where = 0.7; D = 10m; fD= 11GHz; c=3.108m/s

GRe = 59.675 dB

2

D

Re c

Df

log10G

T

L!


23/25

Downlink budget

Downlink noise calculation

- Universe noise temperature is Tu =2.760K

- Sun noise temperature is Tsu

= 500K

- Space noise temperature is

TS = Tu + Tsu =52.760K

+Tm average temperature of rain

Tm =1.12* Txq 50 =2860K

+ Wave attenuation caused by rain is

- Rain noise temperature TM

dBL DRL

M 3.2610104.59510/)( !!!

Kr5


24/25

Downlink budget

- Noise temperature introduced by the loss of thefeeder line is

- Receiver noise temperature TR ~ T1 ,where T1 isnoise temperature of the first module of earthstation receiverLets give TR = 150

oK

- System noise temperature

= 4720K

K678.77)()(TT .FF r!!!

5259.

678.77

259.

27576.52T

TTTT R

F

F

F

ASsys

!

!


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Downlink budget

- System noise power

- Downlink carrier-to-noise ratio (C/N)D

Blog10Tlog10klog10N syssys !6106log10472log106,228 v!

dBW.126!

38.65221.0550EI PC s !!

dBW67,105!

dBW63.203.12667.105NC)N/C( sysE !!!

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