vsat presentation 3

8/10/2019 VSAT Presentation 3

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VSAT Technology andApplications

Prepared for the Israel Amateur Radio Club

By: 4X1DA Rich Harel

November 14, 2002
http://www.qrz.com/callsignmailto:[email protected]:[email protected]://www.qrz.com/callsignhttp://www.iarc.org/


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Agenda

Introduction to Gilat Satellite NetworksWhat is a VSAT ?Typical VSAT ApplicationsSatellite Communication FundamentalsVSAT Network ArchitecturesAccess SchemesNetwork ComponentsNetwork ManagementVSATs Applications in Amateur RadioDemonstration of EquipmentSummary


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Gilat Satellite Networks Ltd.


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Gilat Satellite Networks Ltd.

Founded in 1987Over 950 employees worldwideCore technology: End-to-end two-way satellite broadband platformSales, service and support offices worldwideTraded on NASDAQ (GILTF) since 1993Revenues in 2001: $389MHeadquartered in Petech Tikva, IsraelThree Regional Headquarters:

Spacenet (North America) Mclean, VA

Gilat Latin America Sunrise, FL

Gilat Asia, Pacific Rim and Africa Petach Tikva, Israel


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What is a VSAT ?

VSAT = Very Small Aperture TerminalSatellite-based Wide Area Network (WAN), withcentrally managed hubRemote site: less than 1.2m dish antennaMulti-service platform: Data, telephony andmultimedia communicationsOptimal for continent-wide networks ofhundreds or thousands of units

Small networks integrated in shared hubservice

Large networks, in the tens of thousands, forInternet access


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VSAT Advantages

Full or partial independence from terrestrial infrastructureCost savings over terrestrial linesNationwide reach, distance-independent Network management from a single pointQuick deployment, network flexibilityConsistent and rapid response timeIncreased network availabilityand reliabilityInherent broadcast / multicast platform


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Unicast, Multicast, Broadcast

Each Unicast Packet is Numbered and Acknowledged


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Unicast, Multicast , Broadcast

Multicasts Packets are Not AcknowledgedDifferent Data Steams can be sent simultaneously to many users


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Unicast, Multicast, Broadcast

Broadcast Packets are sent to all users in the Network SimultaneouslyBroadcasts are Not AcknowledgedVSAT Networks can use Reliable Br oadc ast Protocols and applicationsthat are based on NACK s, not ACK s
http://localhost/var/www/apps/conversion/tmp/scratch_9/Reliable.exehttp://localhost/var/www/apps/conversion/tmp/scratch_9/Reliable.exehttp://localhost/var/www/apps/conversion/tmp/scratch_9/Reliable.exehttp://localhost/var/www/apps/conversion/tmp/scratch_9/Reliable.exe


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VSAT SpeedsCompared to Dialup Modem

The name of the game is THROUGHPUT !A 56K Modem will typically connect at speeds of only 43Kbps


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VSAT Markets

EnterpriseRetail; Oil & Gas; Banking; Government

POS; Back Office; Browsing; Telemetry

TelephonyPublic: Public Call Offices, small businesses,farmers, private lines

Corporate: Telephony/Data infrastructure

Internet (IP)High-speed, always-on, Internet-access forconsumers, small businesses and schools

Intranet and IP infrastructure for the enterpriseIP multicast-based services

BTV

Content delivery


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Characteristics of GEO Satellites

35,680 Km above the Earth~24 Hour PeriodAverage 14-17 Year LifespanSingle Satellite theoretically can provide up to 42% Earth CoverageLarge, expensive, difficult to launchLocated approximately every 2

above the equatorSeveral Satellites may operate at the same azimuth on differentfrequencies/polarization


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The Clarke Belt

xx


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GEO/LEO ComparisonGeosychronous (GEO) Low Earth Orbit (LEO)

Example Eurosat Hot-Bird Series IridiumReferredto as:

Fleet Constellation

SuitableFor:

TV/Radio Broadcasts;VSAT/Data CommunicationsNetworks; Telephony Networks;Data Multicast

Handheld Global Telephony Networks;Remote Sensing; Reconnaissance;Weather

Altitude 35,680 km 200-1400 kmOrbit Geosynchronous (Inclination 0 0) Polar (Inclination 90 0)Period 24 Hours AOS-LOS Depends on Altitude

(Period Typically 90 Minutes)Cost 200-300m $US Relatively CheapStand-Alone

Yes (Bent -Pipe) No (Works in a Constellation)(*Single LEO Satellites must beconstantly tracked and suffer fromDoppler Effect )

Size 20-30 meter span As small as 13

mBands C; X-C; KU; Ka Primarily VHF/UHF; L-BandDelay Minimum 240ms MinimalBitrate DVB 2.5-52 Mbps Low Bit RatesEIRP 30-54 dBW Depends on SatelliteFrequencyRe-Use

No (Only on OrthogonalPolarization)

Yes (On Non-Adjacent Spot Beams)

Launch Single Payload (>4000 kg LiftCapability)

Multiple; Can be Piggybacked

Life Span 14-17 Years 4-8 Years


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Geosynchronous Orbit Fleet


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LEO Orbit ConstellationGlobalstar

Loral initiativeSubsidiary of Airtouch (Cellular)

Aimed at global cellular phone coverageQualcomm based CDMA

48 satellite constellation (8 planes x 6 ea. + 4spares)

52 now in orbit !8 orbital planes of 6 satellites each80% Earth coverage (+/- 68 degrees)

LEO orbit (1414 km)Ground Operations Control Centers (GOCCs)and Satellite Operations Control Centers(SOCCs) control gateway and control functions

Qualcomm GSP1600
http://www.geom.umn.edu/~worfolk/SaVi/constellations.html


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Obtaining Satellite Detailshttp://www.lyngsat.com
http://www.lyngsat.com/http://www.lyngsat.com/http://www.lyngsat.com/http://www.lyngsat.com/


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Obtaining Satellite Detailshttp://www.lyngsat.com
http://www.lyngsat.com/http://www.lyngsat.com/http://www.lyngsat.com/http://www.lyngsat.com/


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Satellite Details Amos 1http://www.spacecom.co.il/

Middle East Beam
http://www.spacecom.co.il/http://www.spacecom.co.il/http://www.spacecom.co.il/http://www.spacecom.co.il/


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Satellite Details Amos 1http://www.spacecom.co.il/

European Beam
http://www.spacecom.co.il/http://www.spacecom.co.il/http://www.spacecom.co.il/http://www.spacecom.co.il/


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VSAT Network ArchitecturesOne Way

One-Way Receive OnlyHigh Bit-Rate DVB Compliant Outbound

Inbound Return Channel via Dial-Up Modem

Can be used with existing infrastructure

Example: Harmonic s CyberStream TM

Satellite

Router

Internet

RFTIP Encapsulator

DVB Modulator

VSAT TVRO Antenna

DVB Receiver

LAN

Modem/ISDNReturn

BasebandEquipment

TCP/IP ACK s NACK s


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VSAT Network ArchitecturesTwo-Way Star Topology

All VSATs Communicate via a Single HubNetwork is Independent of Existing InfrastructureVSAT Antenna Size dependent upon Power and Gain of Hub Antenna

Also Upon Inbound Bitrate, ODU Power and Satellite Footprint

Contention Based Access Usually TDMA or FTDMATypical Ping Times Approximately 650-700ms

Hub

VSAT

VSAT

VSAT

VSAT

VSAT

VSAT

VSAT

VSAT


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VSAT Network ArchitecturesTwo-Way Star Topology Double Hop


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VSAT Network ArchitecturesTwo-Way Mesh Topology

VSATs communicate directly with each otherSome systems require initial signaling via the HubLarger Antennas, Higher Power required at the VSATSmaller Antenna, Lower Power required at the HubUsed extensively in Telephony NetworksDelay minimized on VSAT to VSAT Calls

VSAT

VSAT

VSATVSAT

VSAT

VSAT


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Network Components

Skystar 360E


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Typical Hub Configuration


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Network Management

Entire Network Controlled, Configured and Monitored from a SingleLocation called the NOC (Network Operations Center)


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Typical VSAT Indoor Unit(Skystar 360E)

(Front) (Rear)


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Typical VSAT Outdoor Unit/Antenna

LNB

Reflector

LNB-F (Optional)

(Front) (Rear)

Feed-Assembly

SSPA (HPC)

LNB-F (Optional)

LNB


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VSAT Communication Bands

VSAT Networks use Geostationary Satellites (GEO) All located directly above the equator, at an altitude of ~36,000 kmand spaced approximately every 2 degrees

Band Up-Link

(GHz)

Down-Link

(GHz)

Notes

L .9-1.6 .9-1.6 Shared with terrestrial

S 1.610-1.625 2.483-2.5 Shared with ISMBand

C 3.7-4.2 5.925-6.425 Shared with terrestrial

Ku 11.7-12.2 14-14.5 Attenuation due torain

Ka 17.7-21.7 27.5-30.5 High Equipment cost;attenuation due torain


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Space Segment

VSAT Networks lease space segment from the Fixed Satellite Service(FSS) ProviderPrice is mainly determined by Bandwidth and PowerGeosynchronous Satellites frequencies consist of an Uplink andDowlink, each covering a 500 MHz bandwidth

The many transponders operating within this range typically extendfrom 36-72 MHz each

Each Transponder has a finite power level that is shared amongst theusers

Excessive Power levels can cause distortion to all users on thetransponder


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Bit Rate/Symbol Rate

Symbol Rate =Bit Rate

# of bits transmitted with each symbol

If more bits can be sent with each symbol, then the same amount ofdata can be sent in a narrower spectrumFor example, for a bitstream of 80 kbps using BPSK (1 bit persymbol), the symbol rate is the same. For QPSK (2 bits per symbols),the symbol rate is the bit rate or, 40 kbps. For 8PSK (3 bits per

symbol) is would be 1/3 the bit rate, or 26.66 kbps


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0 1

0deg "0"180deg "1"

45deg 00

135deg 10

315deg 01

225deg 11

45o 11 State

135o 10 State

315o 00 State

225o 00 State

Q

I

1 State0 State

Q

I

Q

I

Modulation Types

BPSK Binary Phase Shift KeyingUse alternative sine wave phase toencode bitsSimple to implementInefficient use of BandwidthVery Robust

One bit per symbol (2 States)QPSK Quadrature (Quarternary) PhaseShift Keying

Efficient use of BandwidthRequires more complex receiver fordemodulation

Two bits per symbol (4 States)MSK Minimal Shift Keying

Easy to Generate More ComplexReceiverSpecial form of FSKSpectrally efficient, better noise

performance at receiver


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Forward Error Correction (FEC)

FEC provides the ability for transmitted data to be self -correctingwithout the need for re-transmission (As in ARQ)

Thus, we can transmit with LESS POWER - The price is Overhead and Bandwidth !

FEC means that for every bit sent, an additional bit of overhead issent; means for every 3 bits, one bit of overhead, and so on

BER

10E-1

10E-2

10E-3

10E-4

10E-5

10E-6

3 4 5 6 7 8 9 Eb/N0

Un coded

Coded

Coding

Gain


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Forward Error Correction (FEC)

Two classes of Forward Error Correction codes

Convolutional Codes and Block Codes

Convolutional Coding (Viterbi Decoding)Based on minimum hamming distance code words feed through ashift register

Reed Solomon Code (RS) is a form of Block Code that breaks the

data stream up into fixed size blocks and adds redundancy symbolsOn the other side of the link, the data is decoded using linear algebraicalgorithms . This type of code adds considerable overhead

Concatenated Viterbi refers to an error correction technique whichuses Viterbi in conjunction with Reed Solomon coding. Addsapproximately 2dB to the link budgetTurbo Codes with an even stronger coding gain will eventuallyreplace Convolutional and RS coding


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Bit Error Rate (BER) & Eb/N0

Bit error rate is Directly Proportional to the Eb/N0 ThresholdTypical BER in some VSAT Systems can be


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Link Budget (Margin)

The process of correctly sizing uplink and downlink pathsfor:

Satellite

Hub

Remotes

Takes into account:Satellite performance

Path Loss

Atmospheric effects

Frequency bands

Uplink antenna and amplifier performance

Download antenna size and receiver noise figure

Path Loss at 12 GHz over 36,000 km can exceed 205 dB !


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Access SchemesThe Need for Bandwidth Efficiency

Bandwidth (and power) = $Better bandwidth efficiencytranslates into Cost Savings

Outbound and Inbound BWproportional to:

Number of Users

Bit RatePower/Modulation & ErrorCorrection CodingType of trafficQoS (Quality of Service)

Outbound Transmission:

Constant, Single FrequencyInbound Transmission: Bursty,Frequency HoppingAll VSATs must share theallocated inbound BW

OB IB

F1 F2 F3 F4 F5 F6 F7 Fn


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Access SchemesTime Division Multiple Access (TDMA)

Transmissions occur on thesame frequency frommultiple sourcesWhen a collision occurs,each source waits a randomamount of time before re-transmittingTime slots are allow ed topas s unused

In a loaded network, morecollisions will occur,increasing the random wait

time

Frequency 1

17

11

19

12 17 11

17

18

T i m e

Collision Recognized

11 Retransmits after 3 slots delay time

Retransmits after 5 slots delay time 17

Collision Occurs


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Access SchemesTime Division Multiple Access (TDMA)

Transmissions occur on thesame frequency frommultiple sourcesWhen a collision occurs,each source waits a randomamount of time before re-transmittingTime slots are allow ed topas s unused

In a loaded network, morecollisions will occur,increasing the random wait

time

Frequency 1

17

11

19

12 17 11

17

18

T i m e

Collision Recognized

11 Retransmits after 3 slots delay time

Retransmits after 5 slots delay time 17

Collision Occurs

A S h


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Time

Slots

Time

Frequency

Allocated Bandwidth

120kHz

1.2MHz

053102 006021

Inbound Frequencies

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10

102 053 021006

102021 006

Retransmission 102 006

VSAT 006 VSAT 021 VSAT 053 VSAT 102

Collision102006

Access SchemesFrequency/Time Division MultipleAccess Random Access (RA)


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Access SchemesAutomatic Dedicated Access

A private frequency isallocated to a single VSATCollision free, high throughputchannel for batch applicationsand file transferWhen a DA is required by aVSAT, initiate request is sent in

RA mode, triggered According to IP-socket or IPaddress

According X.25 destinationaddressThroughput based

Then, a DA frequency isallocated

11

25

21

21

14

14

14

f

31

25

17

17

17

17

17

17

17

17

34

DA DA RA

34

34

34

34

34

34

t


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Access SchemesAutomatic Partial Dedicated Access

Partial allocation for betterutilization of DA channelOptimal for Constant Bit Rate(CBR) applications, such as voiceGuarantees fixed response timeDA can be flexibly divide intoPDAs

11

25

t

21

21

14

14

14

f

31

25

15

32

15

32

15

32

17

17

17

17

17

17

17

17

RA


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Access SchemesDual Bit Rate

Support of dual bit rateimproves space segmentsutilizationAny 2 bit rates can besupportedEach VSAT supports two bitrates with multiple access

modesLower bit rate for RA andhigher bit rate for DA

Each Receiver Cage at thehub can handle two bit rates

t

f

17

17

17

17

17

1717

17

15

32

32

15

32

15

DA PDA

76.8 76.8 153.6

36

11

25

21

21

14

14

14

RA


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Acknowledgments over SatelliteSpoofing

The Problem: TCP/IP requires acknowledgment of each and everypacket

The Satellite delay [(36,000/300000)2]2 in addition to all the routersalong the way adds significant latency

Spoofing Concept:

Acknowledge TCP packets locally at the VSAT/Hub SendAcknowledge Summary periodically

No Spoof ing Wi th Spoof ing


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Acknowledgments over SatelliteInternet Page Acceleration (IPA)

On Terrestrial Based Networks, each HTML object is requested andacknowledgedIPA requests all the objects on a specific URLAll objects on an HTML Page are sent to the VSATs at once


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Amateur Radio ApplicationsInternet-to-Radio Link

Typical Node

VSAT Antenna

PC + Sound Card + VoIP Application

VSAT

Radio/PC Interface

VHF/UHF Conventional or Trunked Repeater

VHF or UHFOmni


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Amateur Radio ApplicationsInternet-to-Radio Link

New York Repeater/VSAT

Boston Repeater/VSAT

London Repeater/Direct

Hub

VoIPServers

Internet

VoIP Internet Direct


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Amateur Radio ApplicationsInternet-to-Radio Link - eQSO

xx


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Amateur Radio ApplicationsInternet-to-Radio Link - Echolink


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Amateur Radio ApplicationsHF Remote Base/Diversity Reception


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FAQs (1)

What are the Largest VSAT Networks in the World ?Starband ~44,000 (US ISP); US Postal Service ~33,000

How many VSATs are operation World-Wide ?>400K installed by Gilat alone

Can a Star VSAT communicate with another VSAT without a Hub ?Star Topology No. Mesh Topology VSATs can operate Point-to-Point.

Can a VSAT work Mobile ?No, due to the associated delay is some systems and antenna pointing issues.Mobile systems are under development.

Can a VSAT be used anywhere ?No. It can not be used at the extreme North and South latitudes due to coverageof Geostationary satellites. You must have line-of-site coverage towards thesatellite your network is working on.

What are typical upsteam and downsteam speeds that can be achieved with aVSAT ?

Depends on the VSAT ISP. Btopenworld in the UK is offering 500/120 kbps(Upstream/Downstream) service. Theoretically, much higher speeds can beachieved.


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FAQs (2)

Can I view DVB-S video stream from the same antenna/LNB ?Yes. (So long as it is on the same satellite). Elliptical antennas allow adding twoadditional LNBs with switchable polarization.

How many PC s can I connect to a VSAT ? Theoretically, as many as you want. The limiting factor is that they will be sharingthe Inbound/Outbound Bandwidths. The other limiting factor is the total number

of TCP/IP sockets and whether or not the VSAT ISP set up the VSATs to assignan IP address to connected PC. Up to 4 is recommended.

What applications are NOT suitable for VSATs ?VSAT traffic has an inherent latency due to the distance. Real-Time InternetGamming other time-critical applications will not work as well as terrestrial lines.

What changes can we expect to see in the future concerning VSAT technology,markets ?

When Ka-Band Satellite service begins, we can expect to see much smallerdishes. 8PSK instead of the current QPSK on the Outbound, Internal Caching onVSAT, plus much more.

The Rural Telephony market is booming and when mobile VSAT equipmentbecomes available, the industry is expected to change entirely.


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Probing Further

Gilat Satellite Networks Spacenet (Gilat Subsidiary in US) FAQ s (Btopenworld Satellite Service) Lyngsat (Geostationary Satellite Database) Phase Modulation Tutorials

Digital Modulation Basics MPEG Tutorial DVB Standards Tutorial FEC Tutorial Spectrum Analysis Basics Spectrum Analysis AM-FM Measurements www.satil.com (Israeli TVRO Information in Hebrew)AFRTS TVRO Satellite Handbook Channel Master VSAT Antennas Telecommutations Glossary
http://www.gilat.com/Home.asphttp://12.32.10.154/tools/satellite_basics/http://www.btopenworld.com/satellite/faqs.htmlhttp://www.lyngsat.com/http://www.newwaveinstruments.com/resources/rf_microwave_resources/sections/digital_modulation_tutorial_theory_technique.htmhttp://cp.literature.agilent.com/litweb/pdf/5965-7160E.pdfhttp://www.educatorscorner.com/tools/lectures/slides/pdf/MPEGtutorial1.pdfhttp://www.dvb.org/dvb_technology/whitepapers.htmlhttp://grouper.ieee.org/groups/802/16/tutorial/80216t-00_01.pdfhttp://cp.literature.agilent.com/litweb/pdf/5952-0292.pdfhttp://www.ece.wpi.edu/research/analog/resources/hp-am-fm.pdfhttp://www.satil.com/http://www.afrts.osd.mil/tech_info/page.asp?pg=handbookhttp://www.channelmaster.com/http://www.its.bldrdoc.gov/fs-1037/http://www.its.bldrdoc.gov/fs-1037/http://www.channelmaster.com/http://www.afrts.osd.mil/tech_info/page.asp?pg=handbookhttp://www.satil.com/http://www.ece.wpi.edu/research/analog/resources/hp-am-fm.pdfhttp://www.ece.wpi.edu/research/analog/resources/hp-am-fm.pdfhttp://www.ece.wpi.edu/research/analog/resources/hp-am-fm.pdfhttp://cp.literature.agilent.com/litweb/pdf/5952-0292.pdfhttp://grouper.ieee.org/groups/802/16/tutorial/80216t-00_01.pdfhttp://www.dvb.org/dvb_technology/whitepapers.htmlhttp://www.educatorscorner.com/tools/lectures/slides/pdf/MPEGtutorial1.pdfhttp://cp.literature.agilent.com/litweb/pdf/5965-7160E.pdfhttp://www.newwaveinstruments.com/resources/rf_microwave_resources/sections/digital_modulation_tutorial_theory_technique.htmhttp://www.lyngsat.com/http://www.btopenworld.com/satellite/faqs.htmlhttp://12.32.10.154/tools/satellite_basics/http://www.gilat.com/Home.asp

vsat presentation 3

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