PC2: SATCOM and Footprints Flashcards
Identify
Utilizes microwave frequencies to exchange voice, data, and video information by either wired or wireless methods
Terrestrial Communication
Identify
Employs satellites and Earth ground stations to exchange voice, data, and video information
Satellite Communication (SATCOM)
What are the SATCOM Advantages?
- Mobility/Flexibility
- Beyond Line-of-Sight (LOS)
- Coverage
- Cost effective
What are the SATCOM Disadvantages?
- Congestion of frequencies
- Interference
- Propagation
What are the SATCOM Applications?
- Radio and TV broadcasting
- Internet Applications
- Commercial Communications
- Military Communications
What is the SATCOM Process?
- An uplink is established (Earth to satellite)
- The satellite amplifies the incoming signal and changes the frequency
- Downlink commence (satellite to Earth)
- The ground equipment receives the signal
What are the two One-Way Communications?
- Broadcast
- Multicast
What is the Two-Way Communication?
Point-to-Point
What are the 3 SATCOM Segments?
- Ground/User
- Space
- Link
Identify
Consist of the ground facilities and antennas required to control the satellite (TT& C) and all terminals
SATCOM Segment
Ground/User
Identify
Consist of military and commercial satellites in orbit
SATCOM Segment
Space
Identify
Connects the ground and space segment together through the electromagnetic spectrum
SATCOM Segment
Link
What are the 3 Earth Station Components?
- Outdoor Unit (ODU)
- Indoor Unit (IDU)
- Inter Facility Link (IFL)
Identify
Components or subsystems installed in an outdoor location
Earth Station Component
Outdoor Unit (ODU)
Identify
Components or subsystems installed in an indoor location or weatherproof shelter
Earth Station Component
Indoor Unit (IDU)
Identify
Cable system to connect an ODU and IDU
Earth Station Component
Inter Facility Link (IFL)
Give an example of an Outdoor Unit (ODU)
- Antenna and antenna base
- Feed horn
- Filters
- Low Noise Block (LNB)
- Block Up Converter (BUC)
Give an example of an Indoor Unit (IDU)
- Modems
- Satellite Receivers
- Tracking Devices
Give an example of an Inter Facility Link (IFL)
- RF Signals
- Monitor and Control (M&C)
- Power
What are the 3 SATCOM Terminal Types?
- Fixed
- Transportable
- Mobile
Identify
In-place
SATCOM Terminal Type
Fixed
Identify
Designed to be movable, but once on location remain fixed
SATCOM Terminal Type
Transportable
Identify
Land, maritime, aerospace, etc.
SATCOM Terminal Type
Mobile
Identify
A circuit which increases the strength of the signal it receives and retransmit it
Microwave Repeater
What are multiple channels called?
Transponders
They provide bandwidth and power over designated radio frequencies.
“How much we have”
“refers to data capacity of a channel. It is defined as the potential of data which can be transferred in specific period of time”
Bandwidth
“How much we actually transmitted”
“refers to measurement of data transferred in a specific time period. It is also termed as effective data rate or payload rate”
Throughput
Identify
Any data rate less than 64 kbps
Data Rate Considerations
Low Data Rate (LDR)
Identify
Any data rate between 64 kbps and 1536 kbps
Data Rate Considerations
Medium Data Rate (MDR)
Identify
Any data equal to or greater than 1536 kbps
Data Rate Considerations
High Data Rate (HDR)
Identify
Provides 8.192 Mbps
Data Rate Considerations
Extreme Data Rate (XDR)
Identify
A beam which covers a wide area such as the entire continental US (CONUS)
Wide Beam
Identify
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
Multi Beam Antenna (MBA)
- Power to each beam is adjustable
- Have a single aperture (the entire footprint is denied)
Identify
- Reduced transmission delay
- Reduced launch cost
- Reduced path loss
- Lower power
- Great for mobile cellular services
Low Earth Orbit (LEO) Advantages
Identify
- 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
Low Earth Orbit (LEO) Disadvantages
Identify
- Visibility for longer periods than LEO (2-8 hrs.)
- Larger coverage area than LEO
- Wider foot print than LEO
- Fewer satellites than LEO
Medium Earth Orbit (MEO) Advantages
Identify
- Transmission delay more than LEO
- More transmitting power than LEO
- Exposed to space debris and atmospheric drag
- Weaker signal than LEO
Medium Earth Orbit (MEO) Disadvantages
Identify
- Global view (three satellites)
- No ground station tracking required
- No-Inter satellite handoff
- Almost no Doppler shift
- 24 hours view of a particular area
Geo-synchronous/Geo-stationary Earth Orbit (GEO) Advantages
Identify
- Poor Coverage at high latitudes (cannot see latitudes > 77˚)
- Heavily regulated by the ITU
- High transmission latencies
- Weak received signal
Geo-synchronous/Geo-stationary Earth Orbit (GEO) Disadvantages
What orbit is the most commonly used in SATCOM?
GEO
What orbit is used for special applications where coverage of high latitude locations is required?
Highly-Elliptical Orbit (HEO)
Identify
A ground station that relays data to/from the satellite to the local area network
SATCOM Link Segment
Satellite Gateway
It houses the antennas and equipment to convert RF signals to an Internet Protocol (IP) signal for terrestrial connectivity.
Also referred to as a teleport or hub.
Identify
Basic strategy used to get a signal around the Earth via satellite
SATCOM Configuration
Bent Pipe
Also known as M-Hop
Identify
Anti-jam, survivable technique used to get a signal around the Earth via satellite
SATCOM Configuration
Crosslinks
Identify
- Mobile applications
- Employs variety of ground equipment
SATCOM Frequencies
L-Band (1-2 GHz)
Identify
- Lower transmission power over wide geographical area
- Requires larger ground equipment (Antenna 1.8 M)
- Better on adverse weather on the ground
SATCOM Frequencies
C-Band (4-8 GHz)
Identify
- Mainly Military applications
- Employs variety of ground equipment
- Less crowded frequency
- Less affected by adverse weather
SATCOM Frequencies
X-Band (8-12 GHz)
Identify
- Higher transmission power over a small geographical area
- Uses smaller ground equipment (Antennas 0.8-0.9m)
- Affected by snow and rain
SATCOM Frequencies
Ku-band (12-18 GHz)
Identify
- Higher transmission power than Ku
- High bandwidth services (such as high-speed internet, video conferencing and multimedia applications)
- Antenna sizes 60 cm-1.2m
- Affected by snow and rain
SATCOM Frequencies
Ka-band (26-40 GHz)
Which SATCOM frequency is used for mobility?
UHF
Which SATCOM frequency provides high data rate?
SHF
Which SATCOM frequency is used for nuclear survivability?
EHF
Identify
Uses ground equipment at set locations to receive and transmit satellite signals
SATCOM Services
Fixed Satellite Services (FSS)
Supports:
* Majority of domestic and international services
* International internet connectivity
* Private business networks
Identify
Uses a variety of transportable receiver and transmitter equipment to provide communications services for land mobile, maritime, and aeronautical users
SATCOM Services
Mobile Satellite Services (MSS)
Identify
Offers high transmission power for reception using very small ground equipment
SATCOM Services
Broadcast Satellite Services (BSS)
BSS is best known for direct-to-consumer TV and broadband application.
Identify
Military dedicated Satellite Communications
SATCOM Services
Military (MILSATCOM)
Communications Types:
* Narrowband Communications
* Wideband Communications
* Protected Communications
Identify
Supports worldwide tactical communications, including in-route contingency communications, in-theater communications, intelligence broadcast, and range extension for combat net radios
SATCOM Services
Narrowband Communications
- UHF Follow-On (UFO)
- Mobile User Objective System (MUOS)
Operates in the UHF band and commercial L and S bands
Identify
Support high data rate communications for the execution of C2, crisis management and intelligence data transfer
SATCOM Services
- Defense Satellite Communications System (DSCS)
- Wideband Global Satellite (WGS)
- Non-classified Internet Protocol Network (NIPRNET)
- SECRET Internet Protocol Network (SIPRNET)
- Joint Worldwide Intelligence Communications Systems (JWICS)
- Video teleconferencing (to deployed forces)
Operates in C, Ku, K, Ka, S, and X bands
Jam-resistant communications at the strategic, operational, and tactical level
Protected Communications
- Military Strategic and Tactical Relay (MILSTAR)
- Advanced Extremely High Frequency (AEHF)
- Enhanced Polar System (EPS)
Operates in EHF (downlink) and EHF (uplink) band
Identify
Can be defined as the time it takes for a signal to travel up to a satellite and back down to a receiving station
SATCOM Limitations & Vulnerabilities
Transmission Delays
Note: Real-time communications prefer shorter the transmission delays
Identify
- Due to the gravitational pull of the Sun and Moon
- Largest perturbation concern
- Most demanding on satellite’s fuel reserves
SATCOM Limitations & Vulnerabilities
North-South Perturbations
Identify
- Due to Earth’s triaxiality
- Affects satellite’s velocity and altitude
SATCOM Limitations & Vulnerabilities
East-West Perturbations
Identify
Satellite lateral errors can be as much as ± 3˚ at the end of life
SATCOM Limitations & Vulnerabilities
Satellite Positioning
Identify
There are two solar eclipses (Vernal and Autumnal Equinoxes) for about 6 weeks each year
SATCOM Limitations & Vulnerabilities
Solar Outages
Satellites are in the Earth’s shadow for a few minutes to as much as 65 minutes on the day of the equinox
Identify
What happens when the satellite eclipses the Sun?
SATCOM Limitations & Vulnerabilities
Becomes exposed to background noise build up
Identify
This interferes with nearby satellites
SATCOM Limitations & Vulnerabilities
Side lobe Radiation Problem
Note: Antenna shapes are often skewed to lower the side lobes
Identify
Not all satellites are located above the Earth station. At lower elevation angles signals traverse more atmosphere, thus the overall what is increased?
Slant Range
What is the most common adverse effect on signal transmissions?
Rain Fade
What must you have to burn through adverse weather?
Power to spare
Satellite communications system that can be setup with a two-way ground station connected to a dish antenna that points to or tracks a particular satellite
Very Small Aperture Terminal (VSAT)
