slide ttvt chapter6
TRANSCRIPT
-
8/3/2019 Slide TTVT Chapter6
1/22
Link BudgetCalculation
-
8/3/2019 Slide TTVT Chapter6
2/22
Introduction
A satellite communication link is defined as anEarth station - satellite - Earth stationconnection.
The Earth station - satellite segment is calledthe uplink.
The satellite - Earth station segment is calledthe downlink.
-
8/3/2019 Slide TTVT Chapter6
3/22
Introduction
The Earth station design consists of theTransmission Link Design (Link Budget) andthe Transmission System Design.
Link Budgetestablishes the resources neededfor a given service to achieve the performanceobjectives.
-
8/3/2019 Slide TTVT Chapter6
4/22
Link Budget Calculation between
the VINASAT satellite and
the Earth Station at Tam Ky, QuangNam
-
8/3/2019 Slide TTVT Chapter6
5/22
LinkParameters
* Operation Bandwidth
Link design at Ku-Band, using frequency of14GHz for the uplink and 11GHz for thedownlink.
-
8/3/2019 Slide TTVT Chapter6
6/22
LinkParameters
* Earth Station
- Located at 15,20N latitude and 108,30Elongitude.
- The diameter of the antenna (D) is 13m, theaperture efficiency () is 65%
- Transmission power of Earth Station is 300W.
- Earth station antenna height of 7m above sealevel.
-
8/3/2019 Slide TTVT Chapter6
7/22
LinkParameters
* Satellite
- Located at 1320E longtitude.
- EIRPs = 50dBW.- Transponder Bandwidth is 36MHz.
- Receiver noise figure F = 4dB.
- Receiver figure of merit(G/T)s = 1dB/
0K
-
8/3/2019 Slide TTVT Chapter6
8/22
LinkParameters
* Other suppositions
- Feeder loss LF = 1dB
- Polarization mismatch loss LPOL = 0.5dB
- Antenna misalignment loss 0.9dB
- Rain loss figure = 3.96dB/km, rain height hR =3.208Km
- Tropospheric loss figure 0.02dB/Km- Ambient temperature TX = 300
0K
-
8/3/2019 Slide TTVT Chapter6
9/22
Link Budget
- Slant range distance is
where+ Earth station latitude at Tam Ky = 15.20 N+ Ls = 132
0E , Le = 108.30N
Difference in longitude between the earthstation and the satellite is
Le = 1320 108.30 = 23,70
0 = 27.920
e0 Lcos.coscos
)cosrR2Rr(d 0e2
e
2
884.07.23cos2.15coscos00
0
-
8/3/2019 Slide TTVT Chapter6
10/22
Link Budget
Distance between VINASAT satellite and Earthstation at Tam Ky is
d=36629.4 km
- Elevation angle of satellite from the Earth station e
where Re = 6378 [km]r = 35768 + 6378 = 42146 [km]
tge = 1.565 e = 57.420
0
e0
esin
r
Rcos
tg
-
8/3/2019 Slide TTVT Chapter6
11/22
Link Budget
- Azimuth of the satellite a
A = -59.150
a = 1800 (59.150) = 239.150
- Earth station transmit antenna gain
where = 0.65 ; D = 20m ; fU= 14GHz ; c=3.108m/s
GTe =67.473 [dB]
674.1)2.15sin(
7.23tg
)sin(
LtgtgA
0
0e
2
UTec
Dflog10G
-
8/3/2019 Slide TTVT Chapter6
12/22
Uplink Budget
- Earth station transmit power (300W) in dB is
PTe = 24.77 [dBW]
- Equivalent Isotropic Radiated Power of thetransmitting Earth station is
EIRPe = GTe+ PTe = 92.244 [dBW]
- Uplink total loss is
LU = LSPU + LFU + LOU
-
8/3/2019 Slide TTVT Chapter6
13/22
Uplink Budget
+ 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
At 15,20
N latitude, rain height (adapted from CCIRRecommendation 564) is
hR = 3+ 0.028 =3,028 [km]
hS = 7m = 0,007km ; sine = sin57.420
[dB]206,641)clg(20)df4lg(20L USPU
e
SR
Ssin
hhL
-
8/3/2019 Slide TTVT Chapter6
14/22
Uplink Budget
Ls = 3.585kmU = 3.96dB/km
Uplink rain loss is (LR)U= 14.197dB+ Antenna misalignment losses are
LTe = 0.9dB ; LRs = 0.9dB
+ Polarization mismatch loss isLPOL = 0.5dB
+ Loss due to troposphericeffects is
Ltr=0.02 x 15 = 0.3[dB/Km]
(assuming troposphere height at Tam Ky is 15km)
-
8/3/2019 Slide TTVT Chapter6
15/22
Uplink Budget
Hence, uplink total loss is
LU = LSPU + LFU + LOU= LSPU + LFU + (LRU + LTe + LRs + LPOL + Ltr)
= 206.641 + 1 + (14.197 + 0.9 + 0.9 + 0.5 + 0.3)= 224.438 [dB]
- Satellite receiver noise temperature
vi F = 4dB ; T0 = 2900K
TRS = 4380K
010
F
RS T)110(T
-
8/3/2019 Slide TTVT Chapter6
16/22
Uplink Budget
- Uplink noise temperature is TU = TRS + TAS
where TRS = 4380K ; TAS = 290
0K
TU
= 4380 + 2900 = 7280K
- Satellite receive antenna gain is
GRS= (G/T)S + 10lgTU [dB]
where (G/T)S = 1 dB/0K
GRS= 1 + 10lg728 = 29.62 [dB]
-
8/3/2019 Slide TTVT Chapter6
17/22
Uplink Budget
- Satellite received carrier power is
CRS = EIRPe LU + GRS= - 102.574 [dBW]
- Uplink noise power is NU = 10lgkTUB
where k is Boltzmanns constant (1,38.10-23 [J/K])TU equivalent noise temperature (728
0K)
B is the noise bandwidth of the carrier 36MHz
NU = - 124.4 [dBW]
- Uplink carrier-to-noise ratio
(C/N)U = - 102.574 + 124.4 = 21.826 [dBW]
-
8/3/2019 Slide TTVT Chapter6
18/22
Downlink budget
- Downlink total loss LD
+ Free-space loss is
(Ltd)D= 20lg(4fDd) 20lgc
= 20lg(4x11.109x36629.4x103)-20lg3.108
= 204.55 dB
+ Downlink rain loss is (LR)D= 14.197dB
+ Polarization mismatch loss is LPOL= 0.5 dB
+ Antenna misalignment losses are
LTs = 0.9 dB ; LRe = 0.9 dB
-
8/3/2019 Slide TTVT Chapter6
19/22
Downlink budget
Downlink total loss is
LD = (Ltd)D + (LR)D + LPOL+ LTs + LRe= 204.55 + 14.197 + 0.5 + 0.9 + 0.9
= 221.05 dB
- Earth station receive antenna gain is
where = 0.65; D = 20m; fD= 11GHz; c=3.108m/s
GRe =65.38 dB
2
D
Re c
Df
log10G
-
8/3/2019 Slide TTVT Chapter6
20/22
Downlink budget
* Downlink noise calculation
- Space noise temperature is TS = 52.760K
- Rain noise temperature TMWave attenuation caused by rain is
dB3.261010L 42.110/)L(MDR
K275)3.26
11(286)L
11(TT
M
mM
-
8/3/2019 Slide TTVT Chapter6
21/22
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 earth stationreceiverLets give TR = 150
oK
- System noise temperature
= 4720
K
K678.77)110(300)1L(TT 1.0F0F
150259.1
678.77
259.1
27576.52T
L
T
L
TTT R
F
F
F
ASsys
-
8/3/2019 Slide TTVT Chapter6
22/22
Downlink budget
- System noise power
- Downlink carrier-to-noise ratio (C/N)D
Blog10Tlog10klog10N syssys 61036log10472log106,228
dBW3.126
38.65221.0550GLEIRPC ReDsRe
dBW67,105
dBW63.203.12667.105NC)N/C( sysRED