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

Slant pathSlant path

LLpathpath

RainRainheightheight~3km~3km

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

Directional coupler/power divider

Right beam 1 2 0.707 / 90o

1V / 0o 0.707V / 0o

Left beam 4 3 0.707 V / 0o

1V / 0o 0.707V / 90o