Basic Satellite Communication
(5)
Ground Segment and Practical
Aspects of SatCom
Dr. Joseph N. Pelton
Typical VSAT System
Applications
(Very Small Aperture Terminals)
• Credit Card Validation
• ATM/Pay at the Pump
• Inventory Control
• Store Monitoring
• Electronic Pricing
• Training Videos
• In-Store Audio
• Broadband Internet Access
• Distance Learning
Apartment
Buildings
Corporate Offices
Residential
Gas
Stations
Branch offices
Corporate
Data Center
Key Trends for Satellite and User Terminals

Satellite in general are becoming more capable, with higher
power and larger aperture antennas to promote frequency re-use
and higher flux density. Thus satellites are increasingly massive
(due to antenna and power systems) but are, in essence, highly
capable “super-computers-in-the-sky” with specialized digital
software.
 This allows user terminals to become smaller, lighter in weight
and still handle broader band services. This is sometimes called
technology inversion. Overall systems costs have decreased
because of the explosion of low cost user terminals that can now
receive video via hand-held units.
 User terminals with Geo-systems do not have to be re-pointed,
but LEO or MEO-systems must be able to track or have omni
(or quasi-omni) antennas so that signals can be received from all
possible angles.
Key in User Terminals

Growth in VSATs towards 1 million with
virtually all of them optimized via new IP over
Satellite (IPoS) standard.
 Size of VSATs has decreased from around 3
meters down to about 1 to 1.2 meters and costs
have continued to decline especially driven by
Digital Video Broadcast and DOCSIS standards
that allow very high speed low cost links (i.e. 45
to 60 Mbps) with return channel service (RCS)
that allows up stream speeds in the 56 to 384
kbps range.
Ground Equipment Trends
Terminals
Omni directional or “patch” antennas
 Smaller, lighter, cheaper
 Yet more capable (i.e. video signals & broadband)
 Pocket, notebook, rugged
 Sophisticated (ASIC driven) yet simple
 Application specific terminals, embedded modems
Phones
 Satellite capability + 3 GSM frequencies + “video”
 Voice, Asynchronous Data and Packet Data
 Smaller (antenna and battery in particular)
 Long stand-by mode
Minimal Set-Up Time, Robust, Portable, Easy to Use

Rural – Hybrid Networks

Internet backbone distribution using satellite –
local distribution using 2.4 GHz wireless
Satellite-Fiber Comparison
Comparing Satellite and Fiber Characteristics
Capability
Fiber Optic
Cable Systems
Geo Satellite in
a Global System
Meo Satellite in
a Global System
Leo Satellite in
a Global System
Transmission
Speed
10 Gbps – 3.2
Terabits/second*
Single Sat
1Gbps-10Gbps
Single Sat
0.5Gbps-5Gbps
Single Sat
.01Gbps-2Gbps
Quality of
Service
10-11 - 10-12
10-2 - 10-11
10-2 - 10-11
10-2 - 10-11
Transmission
latency
25 to 50 ms
250ms
100-150 ms
25-75 ms
System
Availability w/o
Backup
93 to 99.5%
99.98%
(C-Ku band)
99% (Ka band)
99.9%
(C-Ku band)
99% (Ka band)
99.5%
(L-C-Ku band)
99% (Ka band)
Broadcasting
Capabilities
Low to Nil
High
Low
Low
Multicasting
Capabilities
Low
High
High
Medium
Trunking
Capabilities
Very High
High
Medium
Low
Mobile Services
Nil
Medium-to-High
High
High
Dramatic decrease in the cost of
Fiber Optic Systems
lifetime
Satellite Based IP Services Growing

Demand for all types of IP based satellite services
is growing including VoIP and MMIP.
 Satellite service today requires special “spoofing”
systems to achieve reasonable transmission
efficiency (85% + possible with the best system
from Mentat, ViaSat, etc. and use of the new IPoS
standards.
 Improvements can be achieved by increasing
window sizes to reduce misinterpretation of
latency for system congestion, spoofing software,
and other modifications to satellites to address IP
Security issues.
Satellite Lifecycle and Failure Modes






Most failures occur at start or end of life
Many satellite failures are due to software or
operator errors rather than hardware failures
Infant Failures (deployment of antenna and solar
arrays, failure to reach proper orbit, etc.)
End-of-Life Failures and Wear-out (MTTF)
Bathtub Curve of Satellite Failures
Catastrophic Failures can occur at any time.
(Orbital debris, Electro-Magnetic Storms, Cosmic
Rays, Micro-meteorites, etc.)
Satellite Employment Patterns
1998-2004 (97,000 to 162,000)
190,000
170,000
150,000
130,000
110,000
Launch Vehicle
Manufacturing of Experimental
SatCom
Satellite Manufacturing
105,000
Ground Equipment
Manufacturing
Satellite Services
100,000
98,000
96,000
0
1998
1999
2000
2001
2002
2003
2004
Satellite Technologies of the Future

On-Board Processing
 Signal Regeneration
 Advanced Antenna Systems
(hopping/scanning beams, phased-array,
inflatable structures, piezo-electric systems)
 More Efficient Power Systems
 Turbo-coding
 Advanced Modems and Enhanced Vocoder
Algorithms and Error Correction Systems
Satellite Technologies of the Future

More Efficient Use of Spectrum
 New Materials for Light Weight Antennas
and Satellite Construction
 Advanced Orientation and Propulsion
Systems (and Autonomous Operation)
 Advances in Launch Systems
 USATs, VSATs, Micro-terminals (MEMS
& ASIC break-throughs)
Course Review

Satellite Services and Markets (Overview)
 Development of Satellite Technology from
the 1960s onward
 Basic Elements of Satellite Transmission
 Satellite Orbits (Pros and Cons)
 Satellite Frequencies and Spectrum
Allocation
 Key Satellite Terms & Concepts
Assignment

Assignment 6:
– Write short notes on the terms highlighted in
yellow color