High Speed Electronic Circuit High...Wayne Tomasi, “Electronic Communication Systems,” Prentice...

ELCT 1003:

High Speed Electronic

Circuit

Lecture 6: Satellite CommunicationsDr. Mohamed Abd El Ghany,

Department of Electronics and Electrical Engineering

[email protected]

History of Satellite

2Dr. Mohamed Abd el Ghany


Passive Satellite

In 1957, Russia launched Sputnik I, the first active earth satellite.

Sputnik I transmitted telemetry information for 21 days.

Later, in the same year, U.S. launched Explorer I which transmitted

telemetry information for nearly five months.

Active Satellite

The moon became the first passive satellite in 1954, when the U.S. Navy

successfully transmitted the first message over this Earth- to – moon – to –Earth

Communications system

Reflects signals back to earth, as there are no gain devices on board to amplify or

modify the signals.

Is capable of receiving, amplifying, reshaping, regenerating, and retransmitting

information.

History of Satellite



Intelsat I (called Early Bird) was the first commercial telecommunications satellite. It

was launched in 1965 and used to carry one television signal and 480 voice channels.

Syncom I, launched in 1963, was the first attempt to place a geosynchronous satellite into orbit.

Syncom II and Syncom III were successfully launched in 1963, and 1964, respectively. Syncom III

was used to broadcast 1964 Olympic Games from Tokyo.

In 1962, AT& T launched Telstar I, the first active satellite to simultaneously receive

and transmit radio signals. Then Telstar II was launched in 1963. Telstar II was used

for telephone, television and data transmission

Since the syncom projects, a number of nations and private corporations have

successfully launched satellites that are currently being used to provide national as

well as regional and international global communications

The former Soviet Union launched the first set of domestic satellites (Domsats ) in

1966. Domsats are satellites that are owned, operated, and used by a single country.

β

β

Kapler’s Laws



Kapler’s First Law

States that a satellite will orbit a primary body (like Earth ) following an elliptical path.

Because the mass of earth

is substantially greater than

that of the satellite, the

center of mass will always

coincide with the center of

Earth. 𝛼Semimajor axis

𝛼Semimajor axis

F1 F2

An ellipse has two Focal

points (foci), and the center

of mass of a two – body

system is always centered

on one of the foci.

Sem

imin

or

axis

A2

Kapler’s Laws



Kapler’s Second Law

States that for equal intervals of time a satellite will sweep out equal areas in the orbital

plane.

Therefore, velocity V1 must

be greater than velocity V2

earth

For a satellite travelling

distances D1and D2 meters

in 1 second , areas A1 ,A 2

will be equal

satellite

D2

v2

orbit

A1

D1

v1

Kapler’s Laws



Kapler’s Third Law

States that the square of the periodic time of orbit is proportional to the cube of the

mean distance between the primary and the satellite

A = constant

𝛼 = semimajor axis (kilometers)P = the ratio of the time of one sidereal day

(ts = 23 hours and 56 minutes ) to the time of one

revolution of earth on its own axis (te = 24 hours

).

3/2AP

9972.01440

1436

e

s

T

TP

Satellite Elevation Categories



Low earth orbit (LEO)

satellite:

Operate in 1 GHz to

2.5 GHz frequency

range

Orbit approximately

480 miles above

Earth’s surface

Medium earth orbit

(MEO) satellites

Geosynchronous earth

orbit (GEO) satellites:

Operate in 1.2 GHz to

1.66 GHz frequency

Orbit between 6000

miles and 12000 miles

above Earth.

Operate in the 2GHz

to 18 GHz frequency

band.

Orbit 22300 miles

above Earth’s surface.

it takes approximately

1.5 hours to rotate around

earth.

Consequently, the time

that a satellite is in line of

sight of a particular earth

station is 0.25 hours or

less per orbit

It has a rotation period

of between 5 and 12

hours.

It remains in line of sight

of a particular earth station

for between 2 and 4 hours

per orbit.

It completes one

revolution of Earth in

approximately 24 hours.

geosynchronous

satellites appear to be

stationary ,as they remain

in affixed position in

respect to a given point an

Earth.

Requirements for Satellite in

Geostationary Orbits



The satellite vehicle must be orbiting directly

above earth’s equatorial plane

the satellite must also be orbiting in the same

direction as earth’s rotation with the same

angular (rotational) velocity- one revolution per

day.

Satellite System Link Models



Uplink Model

Modulator BPF HPA

To satellite transponder

MW Generator

6 GHz or 14 GHz

RF

RF

IFBPF Mixer

Up-Converter

Baseband in FDM or PCM/TDM




Transponder

BPF BPFLow-

power

amplifier

To earth station 4 GHz

or 12 GHz

MW Shift Oscillator

2 GHz

RF

RF

RFLNA Mixer

Frequency Translator

From earth station

6 GHz or 14 GHz




Downlink Model

BPF BPF

Baseband out FDM

or PCM/TDMMW generator

4 GHz or 12 GHz

IF

RF

RFLNA Mixer

Down-converter

From satellite

transponder

demodula

tor




Cross-Links

Earth

Cross-link

a disadvantage of using intersatellite links (ISL) is :

Uplink/downlinkUplink/ downlink

Satellite System



EgyptSat -1 under assembly in the nose cone of the Dnepr

launcher along with other payloads



Satellite System Parameters



1. Transmit power and bit energy:

Eb=energy of a single bit (joules per bit)

Pt= total saturated output power (watts or joules per second)

Tb=time of a single bit (seconds)

btb TPE




2. Effective Isotropic Radiated Power (EIRP):(equivalent transmit power)

Pin=antenna input power (watts)

At=transmit antenna gain

Lbo=back-off losses of HPA

Lbf=total branching and feeder loss

tinAPEIRP

dBbfdBbodBwtdBwin LLPP




3. Equivalent Noise Temperature (Te):

N=total noise power (watts)

K=boltazman’s constant (joules per kelvin)

B= bandwidth (hertz)

T=temperature of the environment (kelvin)

Te= equivalent noise temperature (Kelvin)

F= noise factor

KTBN

T

TF e1




4. Noise Density (No): is the noise normalized to

a 1-Hz bandwidth

ee

o KTB

BKT

B

NN




5. Carrier-to-Noise Density Ratio (C/No): is the

average wideband carrier power- to- noise

density ratio




6. Energy of Bit-to-Noise Density Ratio (Eb/No):

b

b

o

b

Nf

CB

BN

fC

N

E

)()()( dBf

BdB

N

CdB

N

E

bo

b




7. Gain-to-Equivalent Noise Temperature Ratio

(G/Te): is a figure of merit used to represent the

quality of a satellite or earth station receiver.

G=receiver antena gain

Ts= operating or system temperature

)log(10 s

e

TGT

G

ras TTT

Ta= antenna temperature

Tr= receiver effective input noise

temperature

Satellite System Link Equations






)log(10)log(10)log(10)4

log(20log20 kLT

GDPA

N

Cu

e

int

o

Uplink equation:




)log(10)log(10)log(10)4

log(20log20 kLT

GDPA

N

Cd

e

int

o

Downlink equation:




Example:

Complete the link budget for a satellite with

the following parameters:

-

-

-

-

Reference Book

Wayne Tomasi, “Electronic Communication

Systems,” Prentice Hall, ISBN: 0-13-049492-5



COMM 704:Communication

Systems

Winter 2010

Reference

Amazon will launch thousands of

satellites to provide internet around the

world

3,236 satellites will provide internet from low

Earth orbit

By Jon Porter@JonPorty Apr 4, 2019,

11:18am EDT

https://www.theverge.com/2019/4/4/18295310/amazo

n-project-kuiper-satellite-internet-low-earth-orbit-

facebook-spacex-starlink




Systems

Winter 2010

https://www.theverge.com/authors/jon-porter

https://www.twitter.com/JonPorty

https://www.theverge.com/2019/4/4/18295310/amazon-project-kuiper-satellite-internet-low-earth-orbit-facebook-spacex-starlink

Reference

SATCOM IoT is Ready for Commercialization Spotlight

Suppliers Lining Up to Deliver Products and Services for the

Growing IoT SATCOM Market

Today, the Internet of Things (IoT) is all around us. In our

homes, at our job, and even in our pockets. From connecting

our smart TV and cell phones to automating the production line

at our job, IoT is permeating consumer markets and industrial

production all over the world.

https://gatehouse.dk/satcom-iot-is-ready-for-commercialization/




Systems

Winter 2010

https://gatehouse.dk/satcom-iot-is-ready-for-commercialization/

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