W1. Ch 01 Sattelite Communication

8/14/2019 W1. Ch 01 Sattelite Communication

1/78


2/78

6-Nov-13 2

Agenda

Taaruf

Textbooks

Course content

Assessment and Grading

How to communicate

Q&A


3/78

Taaruf

Assoc. Dr. Rashid A. Saeed Room No. : Room 6

HP : 0961343660

E-mail: [email protected] [email protected]

Facebook: Rashid Abdelhaleem Saeed

Lecture time: 4.00 7.00pm

Tutorial:

Consultation hour: per appointment
mailto:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]:[email protected]


4/78

Textbook(s)


5/78

Assessment and Grading

Method %

Mid-term Examination 30

Final Examination 40

Assignments/Projects/Presentations 20

Quizzes 10

5


6/78


7/78

Ch 1:Overview of Satellite Systems


8/78

Wireless Classification

Wireless system, definition is connectingbetween two point without the use ofwired connection. This can be

accomplished by: Sonic

Infrared

Optical Radio frequency

acoustic

8


9/78

Wireless Classificationcontd

Another way to categorize wirelesssystem as:

Point-to-point (PTP)

Remote control, microwave link, etc

Point-to-multipoint (PMP)

AM and FM broadcast radio and TV,

LMDS: uses in TV broadcast and internet access,i.e. WiMAX

Multipoint-to-multipoint (MTM)

9

What is the different between point-to-point andpeer to peer


10/78

Wireless Communication Systems Today

10


11/78

11


12/78

Intelsat 10 at 68.5 E Africa footprint.

12


13/78

Telestar 12 footprint

13


14/78

NileSat footprint

14


15/78

15


16/78

Advantages of Satellites

The advantages of satellite communicationover terrestrial communication are: The coverage area of a satellite greatly

exceeds that of a terrestrial system. Transmission cost of a satellite is independent

of the distance from the center of the coveragearea.

Satellite to Satellite communication is veryprecise.

Higher Bandwidths are available for use.


17/78

Disadvantages of Satellites

Launching satellites into orbit is costly.

Satellite bandwidth is gradually becoming

used up. There is a larger propagation delay in satellite

communication than in terrestrialcommunication.


18/78

Satellite-Related Terms

Earth Stations

antenna systems on or near earth

Uplink transmission from an earth station to a

satellite

Downlink

transmission from a satellite to an earthstation

Transponderelectronics in the satellite that convert

uplink signals to downlink signals


19/78

Satellite System Elements

19

Space Segment

Satellite

TT&C Ground Station

Ground Segment

Earth Stations

CoverageRegion

SCC


20/78


21/7821

Satellite Subsystems

Communications Antennas

Transponders

Common Subsystem (Bus Subsystem) Telemetry/Command (TT&C)

Satellite Control (antenna pointing,attitude)

Propulsion

Electrical Power

Structure

Thermal Control


22/78

Satellite Services

Fixed Service Satellites (FSS) Example: telephone system, Sat to Cable

Broadcast Service Satellites (BSS) Example: Satellite Television/Radio Also called Direct

Broadcast Service (DBS). In Europe called DTH

Mobile Service Satellites (MSS) Include land mobile, maritime mobile, and aeronautical

mobile. Navigational satellite services i.e. GPS

Meteorological satellite services i.e. Weather andrescue service

22


23/78

Frequency Bands

23

F All ti


24/78

Frequency Allocationsfor Satellite Services

To facilitate frequency planning, the worldis divided into three regions:

Region 1: Europe, Africa

Region 2: North and South America andGreenland

Region 3: Asia, Australia, and the southwest

Pacific

24


25/78

Frequency Bands

Different kinds of satellites use differentfrequency bands. LBand: 1 to 2 GHz, used by MSS

S-Band: 2 to 4 GHz, used by MSS, NASA, deep space research

C-Band: 4 to 8 GHz, used by FSS the "BUD" (Big Ugly Dish)band

X-Band: 8 to 12.5 GHz, used by FSS and in terrestrial imaging,ex: military and meteorological satellites

Ku-Band:12.5 to 18 GHz: used by FSS and BSS (DBS) There are more than 22 FSS Ku band satellites orbiting over North America,each carrying 12 to 48 transponders,

K-Band: 18 to 26.5 GHz: used by FSS and BSS

Ka-Band: 26.5 to 40 GHz: used by FSS


26/78

Space-Earth Frequency Usability

26

Atmospheric attenuation effects for Space-to-Earth as a function of frequency (clear air

conditions). (a) Oxygen; (b) Water vapor. [Source: ITU 1988]

22.2GHz (H20)

53.5-65.2 GHz (Oxygen)


27/78

Satellites orbits

Satellite Orbits

GEO

LEO

MEO

HEO

HAPs

LEO 500 -1000 km

GEO 36,000 km

MEO 5,000 15,000 km


28/7828


29/78

Geostationary Earth Orbit (GEO)

These satellites are in orbit 35,863 km

Objects in Geostationary orbit revolvearound the earth at the same speed as the

earth rotates.

This means GEO satellites remain in thesame position relative to the surface of

earth. now over 200 active commercial

communications satellites in geostationary

orbit.


30/7830


31/78

Low Earth Orbit (LEO)

LEO satellites are much closer to the earththan GEO satellites, ranging from 500 to1,500 km above the surface.

LEO satellites dont stay in fixed positionrelative to the surface, and are only visiblefor 15 to 20 minutes each pass.

A network of LEO satellites is necessaryfor LEO satellites to be useful


32/78

LEO (cont.)

Disadvantages A network of LEO satellites is needed, which

can be costly

LEO satellites have to compensate forDoppler shifts cause by their relativemovement.

Atmospheric drag effects LEO satellites,causing gradual orbital deterioration.


33/78

Doppler Shift

33


34/78

Cospas-Sarsat system

the emergency radio beacons was at a frequencyof 121.5 MHz.

98% of the alerts were false

Due to the interference to this band The 121.5-MHz system relies entirely on the Doppler

shift, the carrier does not carry any identification information.

The power is low, typically a few tenths of a watt, which limits locational accuracy to about 10 to 20 km.

the 121.5-MHz service was terminate onFebruary 1, 2009

34

S r h nd R u S t llit


35/78

Search and Rescue SatelliteAided Tracking (SarSat)

Newer system operating at the band 406MHz are being introduced.

accuracy to 3 to 5 km

The 406-MHz carrier is modulated withinformation such as an identifying code,the last known position, and the nature of

the emergency.

35


36/78

Medium Earth Orbit (MEO)

A MEO satellite is in orbit 8,000 km -18,000 km

MEO satellites are visible for much longerperiods of time than LEO satellites,usually between 2 to 8 hours.

MEO satellites have a larger coverage areathan LEO satellites.

A.k.a. Intermediate Circular Orbits (ICO),


37/78

Highly Elliptical Orbit (HEO)

Known as Molniya Orbit Satellites Used by Russia for decades.

Molniya Orbit is an elliptical orbit. The

satellite remains in a nearly fixed positionrelative to earth for eight hours.

A series of three Molniya satellites can act likea GEO satellite.

Useful in near polar regions.


38/78

Other Orbits (cont.)

High Altitude Platform (HAP) One of the newest ideas in satellite

communication.

A blimp or plane around 20 km above theearthssurface is used as a satellite.

HAPs would have very small coverage area,but would have a comparatively strong

signal. Cheaper to put in position, but would require

a lot of them in a network.


39/78

INTELSAT

Stand for International TelecommunicationsSatellite.

created in 1964 and currently has over 140

member countries

39

one 36 MHztransponder is capable

of carrying about9000 voice channels, ortwo analog TV channels,or about eight digitalTV channels.


40/78

40


41/78

DOMSAT

41


42/78

Direct broadcasting satellite system

42

Characteristics of a few


43/78

Characteristics of a fewcommunications satellites in use

43


44/78

Satellite Application

Satellite Internet

Satellite Mobile

Satellite Radio

Satellite TV

44


45/78

Satellite Internet

45


46/78

Satellite Internet

46

lli


47/78

Satellite Internet

47


48/78

Satellite Mobile

48
http://www.dailywireless.org/2006/01/23/satphones-localize/


49/78

49
http://www.dailywireless.org/2007/02/05/satellite-repeaters-grounded-in-reality/


50/78

Problems

50


51/78

TRANSCEIVER DESIGN

51

l bl k


52/78

Typical receiver blocks

52

Antenna

BBIFRF

(LNB) low-noise block converter

d
http://en.wikipedia.org/wiki/File:Superhet2.png


53/78

Transponder

53

D l i
http://images.google.com.my/imgres?imgurl=http://www.asc-csa.gc.ca/images/satellite-akebono.jpg&imgrefurl=http://www.asc-csa.gc.ca/eng/satellites/sms.asp&usg=__UXBhaExqa7t5C8-_ZBUAso_0qDE=&h=462&w=600&sz=42&hl=en&start=14&um=1&tbnid=_IyElynzTG4chM:&tbnh=104&tbnw=135&prev=/images%3Fq%3Dsatellite%26hl%3Den%26rlz%3D1W1SKPB_en%26sa%3DN%26um%3D1


54/78

Duplexing

54

RF i i h l


55/78

RF communication channel

55

P i Eff


56/78

Propagation Effects

56

RF T i Gl


57/78

RF Transceiver at Glance

57


58/78

58

Digital Communication System

RECEIVER

RFChannel

Output

Data

SourceDecoding

Channel

Decoder

Demodulator

SourceData

SourceCoding

ChannelCoding

Modulator

TRANSMITTER

Di it l T & R


59/78

Digital Tx & Rx

59

FM transceiver vs. Mobile


60/78

Transceiver

60

Disciplines required in RF system


61/78

Disciplines required in RF systemdesign

61

RF Ci it D i H


62/78

RF Circuit Design Hexagon

Several trade-offs in

RF design In digital design only

one main trade-offbetween speed and

power

62

Ulti t bj ti


63/78

Ultimate objective

Single-chip transceiver Minimum external components

Inductors and capacitors integrated onchip

63

A t


64/78

Antenna

Convert RF signal toelectromagnetic waves and viceversa Same antenna is used for Tx and Rx

by using reciprocal feature

Antenna characteristics:

Operating frequency range

Size

Pattern coverage

Radiation pattern of antenna is aplot of the txed or Rxed signalstrength versus position aroundthe antenna

64


65/78

65

Dipl ing Filt r


66/78

Diplexing Filter

isolation Tx and Rx channels, to avoid interference Isolation between Tx and Rx should be about 120dB

Bandpass filterer at the input of the Rx can be used to attenuatethe transmitter signals.

66

Same antenna should be used for Txand Rx

Duplexing filter should be used to

separate Tx from Rx signals, and

Provide attenuation between Tx and Rx

signals

Transmit/Receive (T/R) switch can be used in

half-duplex wireless systems

Antennae 2


67/78

Antennae2

Antenna size decreases with the increasein frequency

=c/f

The gain of the antenna is proportional toits cross-sectional area divided by 2

67

Filters


68/78

Filters

To reject unwanted signals Important parameters:

Cut-off frequency

Insertion loss

Out-of-band attenuation rate Another important factor is integrability with other

circuit components Difficult to integrate high performance bandpass filters in IC

forms Has high insertion loss and low out-of-band attenuation rate

So, it uses off-chip filters located on the circuit board rather thanfully integrated filter

68


69/78

69

All outside even they may being produced from different materials

Filter 2


70/78

Filter2

From 800MHz to 4GHz Most of the BPF made with dielectric resonators which has small

size and high Q and reasonable IL

At IF (below 100MHZ)

BPF made by using Quartz or surface acoustic wave (SAW) devices

SAW filters have very sharp cutoff, but has high IL (20dB)

At higher MW and mmW

BPF uses waveguide resonators

LPFs have less stringent requirements than BPF: usually

are made of simple LC networks

Parallel coupled lines, or

Transmission line stubs

70

Amplifier


71/78

Amplifier

There are three main categories of amplifier usedin wireless:

Low noise amplifier (LNA)

Power amplifier (PA)

IF amplifier

11/6/2013 71

Amplifier 2


72/78

Amplifier2

Importance specifications for Amplifiers: Power Gain (in dB)

Noise Figure (NF)

Intercept point (IP)

Transistor amplifier is non-linear devices

Saturation Saturation happen because the output voltage of an amplifier

cantexceed the bias voltage level.

Saturation is usually only an issue with PAs

Harmonic distortion usually is very low, however at cube of the input signal is

increases.

In practice it is important to keep distortion levels as low as 50-80dB below the output level.

72

Amplifier 3


73/78

Amplifier..3

Si transistors is inexpensive and havefrequencies up to several GHz

Previously Gallium Arsenide (GaAs) transistors

were required for frequencies at above 1GHz, However, GaAs processing is very expensive and

incompatible with silicon-based IC fabrication.

Another promising technology is silicon

germanium (SiGe), Which can be used at higher frequencies than silicon

and lower cost than GaAs,

11/6/2013 73

Mixer


74/78

Mixer

74

Oscillator


75/78

Oscillator

Is required in the Rx and Tx to provide frequencyconversion

Typical Tx and Rx each may use as many as 4-6oscillators

RF oscillators Hartley, Colpitts oscillators

Use transistor with LC network (to control the frequency ofoscillation)

Better frequency control is uses quartz crystal in place of LCresonators (Pierce Oscillator)

In crystal oscillators is difficult to tune the frequency

PLL (frequency synthesizer) can be used for accurateoutput frequency

75

Oscillator 2


76/78

Oscillator2

76

Hartley Oscillator Colpitts Oscillator

Pierce Oscillator Clapp oscillator

Transceiver Architecture for


77/78

ground station

77


78/78

Thank you

Documents

W1. Ch 01 Sattelite Communication