Satellite Earth Segment - Jordan University of Science …hazem-ot/Session 7_ earth segment.pdf · ground facilities (TT&C-tracking, telemetry & Command)

Satellite Earth Satellite Earth SegmentSegment

Satellite SegmentsSatellite Segments

A satellite communications system can be A satellite communications system can be broadly classified into broadly classified into 2 2 segments:segments:

Space Segment: includes the sat. and Space Segment: includes the sat. and ground facilities (TT&Cground facilities (TT&C-- tracking, telemetry tracking, telemetry & Command)& Command)

Earth Segment: consists of the transmit and Earth Segment: consists of the transmit and receive earth stations.receive earth stations.

ReceiveReceive--Only Home TV systemsOnly Home TV systems

Planned broadcasting directly to home TV Planned broadcasting directly to home TV receivers (Direct Broadcast Satellite (DBSreceivers (Direct Broadcast Satellite (DBS--service).service).

Early, CEarly, C--band (band (4 4 GHz), currently the Ku band: (GHz), currently the Ku band: (12 12 GHz).GHz).

Large antennas (Large antennas (3 3 m diameter) were used with m diameter) were used with the Cthe C--band while smaller (<band while smaller (<11m diameter) are m diameter) are currently used with the Ku Band.currently used with the Ku Band.


Outdoor UnitOutdoor Unit

Consists of a receiving antenna feeding directly Consists of a receiving antenna feeding directly into a LNA/converter combination.into a LNA/converter combination.

A parabolic reflector is generally used with the A parabolic reflector is generally used with the receiving horn mounted at the focus.receiving horn mounted at the focus.

)1&3(40 mmD


1212..22--1212..77 GHzGHz 500500 MHzMHz 3232 TV/FMTV/FM withwith 2424MHzMHz eacheach..

AA polarizerpolarizer maymay bebe switchedswitched fromfrom thethe indoorindoor unitunitforfor polarizationpolarization interleavinginterleaving (LHC/RHC(LHC/RHC oror H/VH/Vpolarization)polarization)


TheThe hornhorn feedsfeeds intointo thethe LowLow NoiseNoise BlockBlock (LNB)(LNB)thatthat containscontains anan LNA+ConverterLNA+Converter..

LNBLNB providesprovides gaingain forfor thethe broadbandbroadband 44//1212 GHzGHzsignalsignal thenthen convertsconverts itit toto aa lowerlower frequencyfrequency rangerangesoso thatthat aa lowlow--costcost coaxialcoaxial cablecable cancan bebe usedused asasfeederfeeder toto thethe indoorindoor unitunit ((950950--14501450 MHz)MHz)


Indoor Unit for analog FM/TVIndoor Unit for analog FM/TV

Two tracks are Two tracks are available:available:

-- RF (UHF)RF (UHF)-- A/V jacksA/V jacks

The selected channel is downThe selected channel is down--converted to an IF converted to an IF frequency (frequency (70 70 MHz) where the most gain is MHz) where the most gain is achieved (FM system rather than VSB).achieved (FM system rather than VSB).

1212..22--1212..77 GHzGHz 500500 MHzMHz 3232 TV/FMTV/FM withwith 2424MHzMHz eacheach..

Master Community Antenna SystemMaster Community Antenna System

Digital DBSDigital DBS--TVTV

sec/202.01

241

symbolMMBwRsym

ForFor digitaldigital receivereceive onlyonly earthearth segmentsegment dealsdealswithwith digitaldigital inputsinputs havinghaving basicallybasically QPSKQPSKmodulatedmodulated signalssignals (other(other modmod.. areare alsoalso used)used)

HavingHaving thethe bandwidthbandwidth ofof 2424 MHzMHz andand rollrolloffoff ofof 00..22,, thenthen thethe symbolsymbol raterate RsymRsym::

Bit rates for Digital DBSBit rates for Digital DBS--TVTV

NoteNote:: thisthis tabletable isis truetrue whenwhen thethe domesticdomestic TVTVreceiverreceiver isis digitaldigital (HDTV/SDTV)(HDTV/SDTV)

Outdoor/Indoor Units Outdoor/Indoor Units

TheThe outdooroutdoor unitunit isis veryvery similarsimilar toto thethe analoganalog DSBDSB--TVTV

TransmitTransmit--Receive Earth stationsReceive Earth stationsTransmitTransmit--Receive ES provide TX/RX functions that are Receive ES provide TX/RX functions that are required for telecommunications traffic generally required for telecommunications traffic generally including network TV.including network TV.

TransmitTransmit--Receive Earth stationsReceive Earth stations


Interconnection equipment is required for Interconnection equipment is required for interconnecting the satellite station and terrestrial interconnecting the satellite station and terrestrial network. network.

MUX required for TX where a kind of reformatting MUX required for TX where a kind of reformatting is maintained. Here, Parallel IF stages are used.is maintained. Here, Parallel IF stages are used.


Next, Modulators are used for TX function:Next, Modulators are used for TX function:QPSK/QAM for digital and FM for analog systemsQPSK/QAM for digital and FM for analog systems

The Upconvertor is implemented to upconvert the IF The Upconvertor is implemented to upconvert the IF ((70 70 MHZ) to RF (MHZ) to RF (66,,14 14 GHz)GHz)


Next, carriers are combined and the resulting wideband Next, carriers are combined and the resulting wideband signal is amplified and is fed to the antenna through the signal is amplified and is fed to the antenna through the Diplexer, which allows simultaneous TX/RX operationsDiplexer, which allows simultaneous TX/RX operations

The ES antenna functions both TX and RX modes but at The ES antenna functions both TX and RX modes but at different frequencies (different frequencies (44//66, , 1212//14 14 GHz)GHz)

C band GEO AntennaC band GEO Antenna

3232 mm diameterdiameter ((256256 ton)ton) VeryVery narrownarrow beambeam withwith

calibrationcalibration HeatHeat isis requiredrequired toto

avoidavoid snowsnow attenuationattenuation

Power Supply ContinuityPower Supply Continuity

ContinuityContinuity ofof thethe powerpower supplysupply isis veryvery importantimportant::

11)) powerpower backupbackup withwith multifeedsmultifeeds fromfrom thethe commercialcommercialpowerpower supplysupply

22)) ElectricalElectrical GeneratorsGenerators33)) BatteriesBatteries

Satellite Earth Segment - Jordan University of Science …hazem-ot/Session 7_ earth segment.pdf · ground facilities (TT&C-tracking, telemetry & Command)

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