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Satellite TechnologySatellite Technology
Assoc. Prof Dr Syed Idris Syed HassanAssoc. Prof Dr Syed Idris Syed Hassan School of Electrical and Electronic EngSchool of Electrical and Electronic Eng Universiti Sains MalaysiaUniversiti Sains Malaysia Seri Iskandar , 31750 PerakSeri Iskandar , 31750 Perak
ConceptConcept
Transponder
Earth station (site A) Earth station(site B)
IRRADIUM
downlinkdownlink
uplinkuplink
downlinkdownlink
uplinkuplink
ApplicationsApplications
Communication Communication (truncking call)(truncking call)
TeleconferenceTeleconference TelemedicineTelemedicine TV BroadcastingTV Broadcasting Data communicationData communication Telemetry(TEC, Telemetry(TEC,
remote sensing etc)remote sensing etc)
Weather telecastWeather telecast NavigationNavigation GPSGPS Security/Calamity Security/Calamity
monitoringmonitoring Standard TimeStandard Time militarymilitary
Type of SatellitesType of Satellites
LEO -Low Earth orbital 100-16,000Km LEO -Low Earth orbital 100-16,000Km (90min to 12hrs orbiting the earth)(90min to 12hrs orbiting the earth)
MEO - Medium Earth Orbital 16,000-MEO - Medium Earth Orbital 16,000-36,000 Km (12 - 24 hrs orbiting the 36,000 Km (12 - 24 hrs orbiting the earth)earth)
GEO - Geosynchronous Earth Orbital - GEO - Geosynchronous Earth Orbital - 36,000 Km ( The satellite appears to be 36,000 Km ( The satellite appears to be stationary over one point on earth)stationary over one point on earth)
Look angle (Elevation)Look angle (Elevation)
)sin()sin()cos()cos()cos(cos
cos21.
tan
sin)(
2/12
seesse
s
e
s
es
LLllLL
r
r
r
rrdei
satelliteandstationearthbetweencedisdwhered
ElCos
ElEl
continuecontinue
Le = Earth station LatitudeLe = Earth station Latitude le = Earth station longitudele = Earth station longitude Ls = Satellite latitude ( = 0 for GEO)Ls = Satellite latitude ( = 0 for GEO) ls = Satellite longitudels = Satellite longitude rs = Satellite orbital radius ( ~ 36,000 km for GEO)rs = Satellite orbital radius ( ~ 36,000 km for GEO) re = earth radius = 6370 kmre = earth radius = 6370 km
For GEO satelliteFor GEO satellite
Cos Cos L Cos l le s e ( ) ( )
Looking angle(azimuth)Looking angle(azimuth)
Consider for GEO onlyConsider for GEO only
2
0 5
1tansin sin
sin sin
. ( )
s s L
s s l l
wheres l l L
e
e s
s e e
NN
SS
ESES
SatSat
EEWW
continuecontinue
If Earth station is in the North Latitude ,If Earth station is in the North Latitude ,
the azimuth will be as follow (refer to N)the azimuth will be as follow (refer to N)
Satellite on the Eastof Earth station
Az=180-
Satellite on the Westof Earth station
Az=180+
continuecontinue
If the Earth station is in the South If the Earth station is in the South latitude , the azimuth will be (refer to N)latitude , the azimuth will be (refer to N)
Satellite on the Eastof Earth station
Az=
Satellite on the Westof Earth station
Az=360-
ExampleExample
Parameter MEASAT JCSAT Superb C
Longitude 91.5 E 128 E 144 E
EIRP (ku)54MHz 56.5 dBW 42 dBW 50.8 dBW
Beacon signal 6 Ghz ? 12.747ghzIf 1447.5MHz
12.255ghzif 955.0 Mhz
Vedio IF 980-1170 Mhz 950-1400mhz 1090-1433mhz
Looking anglefrom 100E 5N
El=78.05Az=216.5
El=55.9Az=108.4
El=37.7Az=100.3
Link budgetLink budget
Noise Power Budget for 54 MHz channelNoise Power Budget for 54 MHz channel
Boltzmann’s ConstantBoltzmann’s Constant = - 228.6 = - 228.6 dBW/K/HzdBW/K/Hz
Receiving system noise temp.Receiving system noise temp. = 28.5 dBK= 28.5 dBK
Ku- Band ‘s channel bandwidthKu- Band ‘s channel bandwidth == 77.3 77.3 dBdB
Receiving noise level Receiving noise level - 122.8 - 122.8 dBdB
For C/N about 10 dB to allow rain and other fading For C/N about 10 dB to allow rain and other fading the signal level should be -112.8 dBthe signal level should be -112.8 dB
continuecontinue
C N
P G
kTB RG
EIRP
N LG
where
EIRP Equivalent isotropic radiated power P G
N ceived noise level kTB
L Path lossR
G ceiving antenna gain
R dis ce between earth station and satellite
wavelength of operating frequency
t tr
r pathr
t t
r
path
r
/
Re
Re
tan
4
4
2
2
continuecontinue
In decibelIn decibel
P dB C N dB N EIRP dB G dB L dB
therefore to calculate antenna size we obtain G
G dB P dB L dB EIRP dB
and parabolic size
AG
antenna efficiency
r r r path
r
r r path
r
/
2
4
ContinueContinue
Parabolic antenna diameterParabolic antenna diameter
D G
DG
antenna efficiency
r
r
2 2
2
2
4 4
06
.
ContinueContinue
MEASATMEASAT
G dB C N dB N EIRP dB L dB
dB dB dB dB
dB
This gain can be achieved u g m diameter dish
r r path
/
. .
.
sin . ( ) .
10 122 8 56 5 205
35 7
0 75
continuecontinue
JCSATJCSAT
G dB C N dB N EIRP dB L dB
dB dB dB dB
dB
This gain can be achieved u g m diameter dish
r r path
/
.
.
sin . ( ) .
10 122 8 42 205
50 2
3 6
continuecontinue
Superbird CSuperbird C
G dB C N dB N EIRP dB L dB
dB dB dB dB
dB
This gain can be achieved u g m diameter dish
r r path
/
. .
.
sin . ( ) .
10 122 8 50 8 205
414
1 32
Teleconference SystemTeleconference System
LNA/HPALNA/HPATransceiverTransceiverQPSK modQPSK mod& demod& demod
CODECCODEC
1.536Mbps1.536Mbps
TVTVmonitormonitor
IDUIDU ODUODU
Data communicationData communication
LNA/HPALNA/HPATransceiverTransceiverQPSK modQPSK mod& demod& demod
1.536Mbps1.536MbpsPCPC
RouterRouter
&&TranscieverTransciever
IDUIDU ODUODU
Other factors need to considerOther factors need to consider
Antenna Antenna Rain attenuationRain attenuation Beam FootprintBeam Footprint Mismatch lossesMismatch losses MisalignmentMisalignment Scintillation ~for low elevationScintillation ~for low elevation troposphere/atmospheretroposphere/atmosphere Bit error rateBit error rate
T o a v o i d b l o c k i n gu s e o f f s e t a n t e n n a
n o b l o c k i n g
( 6 ) D e p o i n t i n g e r r o r
A n t e n n a g a i n w i l l b e r e d u c e d a c c o r d i n g t o d e v i a t i o n f r o m t h e t r u e a n g l e . T h i si s g i v e n b y
G d B G d Boe
d b
( ) ( )
1 2
3
2
w h e r e e i s t h e d e p o i n t i n g e r r o r .t h e r e f o r e a t t e n u a t i o n d u e t o d e p o i n t i n g e r r o r i s
A d B e
d B
( )
1 2
3
2
P a r a b o l i c a n t e n n a f e e d
H o r n a a
L e b b
E R R
L e E
L n L n
E - p l a n e S e c t o r i a l h o r n H - p l a n e s e c t o r i a l h o r n
a b
L e
L n
P r i m i d a l h o r n
L Re 2 L Rn 3
D i r e c t i v i t e g a i n
( I ) E - p l a n e s e c t o r i a l
D
L L C x S x
xee n
3 22
2 2
C x t d tx
( ) c o s ( / ) 20
2
S x t d tx
( ) s i n ( / ) 20
2 a n d x = L e / 2 R
( i i ) H - p l a n e S e c t o r i a l
DL R
LC x C x S x S xn
e
n
4
1 22
1 22
( ) ( ) ( ) ( )
xR
L
L
Rn
n1
1
2
/
/
/
/
xR
L
L
Rn
n2
1
2
/
/
/
/
( i i i ) P r i m i d a l h o r n
DL L
D Dpe n
e n 2
3 2
* a l l t h e a b o v e h o r n a n t e n n a s f o l l o w t h e f o l l o w i n g c o n d i t i o n
D a D b
2 2 1 81 2 1 2 0
2 2
2
2
D i s t h e d e s i r e d d i r e c t i v i t ya , b a r e t h e d i m e n s i o n o f t h e f e e d i n g w a v e g u i d e
L s
L s l a n t l e n g t h o f t h e h o r n
R L
s
e
2 22/
F o r l a r g e h o r n ( a s s u m i n g 5 0 % e f f i c i e n c y )
L e 2 L
D
Lne
2
2
R L b LLe
se
( ) /
2
1 4 D / .1 5 4
S c a l a r
U s i n g c i r c u l a r w a v e g u i d e . T h i s t y p e o f f e e d i s u s e d f o r r e c e i v i n g a n t e n n a .I t c o n s i s t s o f 3 - 7 c o n c e n t r i c r i n g s o f a q u a r t e r - w a v e l e n g t h b r o a d .
f e e d
/ 4
L o g p e r i o d i c
L n L 1
f e e d
d n
d 1
F i r s t e l e m e n t
L F1 10 4 8 . w h e r e
FL
DL
D
1 a n d 183 1 0 f m i n
D i s t h e d i a m e t e r o f t h e f i r s t d i p o l e = 2 a 1
LD a
1
14 a 1 i s t h e r a d i u s o f t h e f i r s t e l e m e n tO t h e r e l e m e n t s f o l l o w
a
LL
Dn
n2
; d Ln n 2 ;
21
41t a n
a n d d
d
L
Ln
n
n
n
1 1
G a i n ( d B ) 8 . 0 8 . 5 9 . 0 9 . 5 1 0 . 0 1 0 . 5 1 1 . 0 1 1 . 5 1 2 . 0 0 . 1 3 9 0 . 1 4 7 0 . 1 5 7 0 . 1 6 3 0 . 1 6 8 0 . 1 7 2 0 . 1 7 4 0 . 1 7 6 0 . 1 7 8 0 . 7 8 2 0 . 8 2 2 0 . 8 6 5 0 . 8 9 2 0 . 9 1 6 0 . 9 2 8 0 . 9 4 0 0 . 9 5 0 0 . 9 6 4
H e l i c a l a n t e n n a ( A x i a l m o d e )
S
2 r d
C = d
S
LD e s i g n p a r a m e t e r s2
33
2 C
w h e r e C = d2
33
2 d
5 2 0o o
w h e r e h e l i x a n g l e
S = C T a n a n d L = w i r e l e n g t h p e r t u r n = C / c o s D i r e c t i v i t y
D n S C 1 52
Rain attenuationRain attenuation
1%1%
0.1%0.1%
0.01%0.01%
% of time exceedance% of time exceedance
2020 4040 6060 8080 100100mm/hrmm/hr
rain raterain rate
ContinueContinue
For TV and broadcasting usually the For TV and broadcasting usually the reliability is not very critical , so 99% is reliability is not very critical , so 99% is okay and this equivalent to 1% of okay and this equivalent to 1% of exceedance of timeexceedance of time
For data other digital com the reliability For data other digital com the reliability of 99.99% is probably chosen and this of 99.99% is probably chosen and this is equivalent to 0.01% of exceedance of is equivalent to 0.01% of exceedance of time.time.
continuecontinue
Att aR Lbpath 0 01.
For 99.99% reliability, the attenuation is calculated asFor 99.99% reliability, the attenuation is calculated as
where a and b are constants relied on frequencywhere a and b are constants relied on frequency
RR0.01 0.01 rain rate at 0.01% of exceedance of timerain rate at 0.01% of exceedance of time
LLpath path is slant path where signal passed the rainis slant path where signal passed the rain
F o o t p r i n t s
G s
S i n g l e b e a m 3 d B r = 3 5 , 7 7 5 K m
( 3 d B c o n t o u r ) 1 0 o N
f o o t p r i n td R = 6 3 7 8 K m
1 0 o S 2 0
d / 2 = R s i n 2 0 = 6 3 7 8 X 0 . 3 4 2 0 = 2 1 8 1 . 4 K m
3 d B = 2 ( ) = 2 ( ) = 2 ( a r c t a n ( 0 . 0 6 0 9 7 6 ) )a r c t a n a r c t a n.
,
d
r2 2 1 8 1 4
3 5 7 7 5
= 2 X 3 . 4 9 o = 6 . 9 8 o
G d Bs
4 8 3 6 0 0 6 5
6 9 86 4 5 2 8 1
2.
..
F o r 1 2 G h z - - - - > = 0 . 0 2 5 m
D md B
7 0 7 0 0 0 2 5
6 9 80 2 5 1
3
.
..
F o o t p r i n t c a n b e s t a t e d i n E I R P o r p o w e r d e n s i t y f l u x ( P D F ) c o n t o u r s o f3 d B , 5 d B e t c .
e g
P D F ( d B W / m 2 ) = E I R P ( d B ) - L p ( d B )
w h e r e L p i s t h e p r o p a g a t i o n p a t h l o s s ( i . e 4
2
r )
3 d B c o n t o u r
E I R P = P t G t = 5 6 . 5 d B t h e r e f o r e p o w e r t r a n s m i t t e d = 5 6 . 5 - 2 8 . 1 = 2 6 . 4d B W
P F D = 5 6 . 5 - 2 0 5 . 1 = - 1 4 8 . 6 d B W / m 2
5 d B c o n t o u r
P D F = - 1 4 8 . 6 - 2 = 1 5 0 . 6 d B W / m 2
59 1 9 1 0 0 2 5
0 2 5 19 0 6d B
o
D
.
..
E l l i p t i c a l l y s h a p e b e a m
U s u a l l y u s i n g e l l i p t i c a l l y s h a p e r e f l e c t o r
D 2
D 1
G d B31 2
4 8 3 6 0
D 11
7 0
D 22
7 0
51
1
9 1d B D
a n d
52
2
9 1d B D
A r r a y a n t e n n a sA n t e n n a a r r a y m a y c o n s i s t s o f a r r a n g e m e n t o f d i p o l e s , s l o t s o r p a t c h e s i ns u c h t h a t a d i r e c t i v e b e a m i s f o r m e d .
d s i n
1 d 2 3 N E E e e eo
j k d j k d j N k d 1 2 1s i n s i n s i n. . . . . . . . . .
E N
No s i n /
s i n /
2
2 w h e r e k d s i n
R a d i a t i o n p a t t e r n ( b e a m )m a i n b e a m
31 0 2
d B N d
i n d e g r e e s
s i d e l o b e s
C h a n g i n g t h e d i r e c t i o n o f t h e b e a m e l e c t r o n i c a l l y
u s i n g p h a s e s h i f t e r( p a r a l l e l a r a n g e m e n t )
o
E EN
No
o
o
s i n
s i n
2
2 w h e r e o ok d s i n a n d d < 0 . 5
3
1 0 2d B
oN d
c o s
( s e r i a l a r r a n g e m e n t )
U s i n g d e l a y l i n e
T h e s e r i a l p h s e s h i f t e r a r r a n g e m e n t c a n b e r e p l a c e d b y d e l a y l i n e i n s u c ht h a t
o ok d k L s i n w h e r e L i s t h e e l e c t r i c a l l e n g t h o f t h e d e l a y l i n e .
I m p l e m e n t a t i o n o f m u l t i p l e b e a m
1 2 3
a m p l i f i e r a m p l i f i e r a m p l i f i e r
-
s u m s u m s u m
b e a m 1 b e a m 2 b e a m 3e g . f = 1 2 G h z t h e n = 0 . 0 2 5 m , N = 2 0 d = 0 . 0 0 6 m
301 0 2 1 0 2 0 0 2 5
2 0 0 0 0 6 02 1d B
oN d
c o s
.
. c o s
31 0 2 0 0 2 5
2 0 0 0 0 6 2 02 2 6d B
o
.
. c o s.
31 0 2 0 0 2 5
2 0 0 0 0 6 4 02 7 6d B
o
.
. c o s.
Beam forming Network
Butler beam forming
1 2 3 4 5 6 7 8
-45o -45o -45o -45o
-67.5o -22.5o -22.5o -67.5o
1R 4L 3R 2L 2R 3L 4R 1L
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