SATCOM Principles Flashcards by James Warrack

What are 4 advantages of SATCOM?

1) Mobility/flexibility
2) Beyond line-of-sight (LOS)
3) Coverage
4) Cost effective

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What are 3 disadvantages of SATCOM?

1) Freq congestion
2) Interference
3) Propagation

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What are 4 applications of SATCOM?

1) Radio & TV broadcasting
2) Internet
3) Commercial comm
4) Military comm

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What are the 2 forms of one-way SATCOM?

Broadcast & multicast

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What are the 3 SATCOM segments?

1) Ground/User
2) Space
3) Link

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What are the 3 components of an Earth station?

1) Outdoor Unit (ODU)
2) Indoor Unit (IDU)
3) Inter-Facility Link (IFL) [cables]

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What are the 5 components of an ODU?

1) Antenna & antenna base
2) Feed horn
3) Filters
4) Low Noise Block (LNB)
5) Block Up Converter (BUC)

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What are the 3 components of an IDU?

1) Modems
2) Satellite receivers
3) Tracking devices

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What are the 3 components of an IFL?

1) RF signals
2) Monitor & control (M&C)
3) Power

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What are the 3 types of SATCOM terminal?

1) Fixed
2) Transportable
3) Mobile

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A SATCOM satellite contains multiple channels called ________________ that provide bandwidth and power over designated radio frequencies

Transponders

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What are the 5 functions of a transponder?

1) Receive
2) Amplify
3) Filter
4) Convert
5) Rebroadcast

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The POTENTIAL data transfer is called…

Bandwidth

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The ACTUAL data transfer is called…

Throughput

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What are the 4 data rates and their values?

1) Low Data Rate (LDR): less than 64 kbps
2) Medium DR: 64 to <1536 kbps
3) High DR: equal to or >1536 kbps
4) Extreme DR (XDR): 8.192 Mbps

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SATCOM terminology to describe the targeting of radio signals from a satellite at a specific point on the earth surface (the use of multiple narrow beams with a focused coverage of a small area):

Spot Beams

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What are the 3 advatages of spot beams?

1) Large increase in overall
capacity
2) Broadband services
long-term viable
3) Flexible spatial
redundancy

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What is MBA?

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Multi-beam Antenna

What are the advantages of LEO?

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Reduced transmission delay
Reduced launch cost
Reduced path loss
Lower power
Great for mobile cellular services

What are the disadvantages of LEO?

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Short visibility from any point on
earth (15-20 min.)
Ground stations Tracking required
Inter-satellite handoffs
Potentially large constellations
Radiation effects on solar cell and
electronics lifetime (Van Allen belt)
Need to compensate for Doppler shift
Atmospheric drag effects

What are the advantages of MEO?

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Visibility for longer periods than LEO (2-8 hrs.)
Larger coverage area than LEO
Wider foot print than LEO
Fewer satellites than LEO

What are the disadvantages of MEO?

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Transmission delay more than LEO
More transmitting power than LEO
Exposed to space debris and atmospheric drag
Weaker signal than LEO

Which orbit is most commonly used in SATCOM?

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GEO

What are the advantages of GEO?

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Global view (three satellites)
No ground station tracking required
No-Inter satellite handoff
Almost no Doppler shift
24 hours view of a particular area

What are the disadvantages of GEO?

Poor Coverage at high altitudes (cannot see latitudes > 77˚) Heavily regulated by the ITU Long transmission latencies Weak received signal

What orbit is used for special applications where coverage of high latitude locations is required?

Highly Elliptical Orbit (HEO)

__________________ is a ground station that transmit data to/from the satellite to the local area network.

Satellite Gateway

It houses the antennas and equipment to convert RF signals to an Internet Protocol (IP) signal for terrestrial connectivity.

Satellite Gateway

AKA teleport or hub

Satellite Gateway

Where in the freq spectrum is the "sweet spot" between scintillation & atmospheric effects?

X-band

As you move UP in the freq spectrum: 1) the throughput goes from _____ to _____ 2) antenna size goes from _____ to _____ 3) the spectrum band goes from _____ to _____ 4) susceptibility to rain fading goes from _____ to _____

1) Lower to Higher 2) Larger to smaller 3) Smaller to larger 4) Less to more

Which band is mainly reserved for military applications?

X-band

What are 3 commercial SATCOM services?

1) Fixed Satellite Services (FSS) 2) Mobile Satellite Services (MSS) 3) Broadcast Satellite Services (BSS)

What are 2 examples of commercial satellite systems?

Inmarsat & Iridium

What are the 3 types of military SATCOM?

1) Narrowband 2) Wideband 3) Protected

What are the 2 types of narrowband comm?

UHF Follow-on (UFO) Mobile User Objective System (MUOS)

What are the 6 types of wideband comm?

1) Defense Satellite Communications System (DSCS) 2) Wideband Global Satellite (WGS) 3) Non-classified Internet Protocol Network (NIPRNET) 4) SECRET Internet Protocol Network (SIPRNET) 5) Joint Worldwide Intelligence Communications Systems (JWICS) 6) Video teleconferencing (to deployed forces)

What are the 3 types of protected comm?

1) Military Strategic and Tactical Relay (MILSTAR) 2) Advanced Extremely High Frequency (AEHF) 3) Enhanced Polar System (EPS)

What are the 2 major classes of perturbations?

North-South East-West

Which class of perturbation is a larger concern, and is due to the gravitational pull of the Sun and Moon?

North-South

Which class of perturbation is due to the Earth's oblateness, and affects a satellite's velocity and altitude?

East-West

What are the 2 solar outages (eclipses) that SATCOM has to deal with each year (for a total of 6 weeks)?

Vernal & Autumnal equinoxes

What is VSAT?

Very Small Aperture Terminal

SATCOM Principles Flashcards

(43 cards)