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Question 1

Define Satellite

Answer 1

A body that orbits another body in space

Question 2

Types of satellites

Answer 2

Natural e.g. moons, planets

Man-made e.g. LandSat, Hubble Telescope, Sputnik, Skynet

Question 3

Purpose of Sat Comms

Answer 3

Observation
Navigation
Weather
Research
Communication

Question 4

One of the Satellite purposes is Communication, what do Military use it for?

Answer 4

Global Comms
Small Footprints
Rapid Deployments
In-theatre Reachback

Question 5

Who envisioned the Wireless World and what date? What is it?

Answer 5

1945, Arthur C Clarke

3 Satellites 120° apart, Travelling West to East (or any direction), gives world-wide communication.

Question 6

Which UK SkyNet satellite is still in operation?

Answer 6

SkyNet 4/5

Question 7

5 Principles of Satellite Communication

Answer 7

Satellite
Tx
Rx
Power
Line of Sight (LOS)

Question 8

What are the 5 reasons for demand of SatComs?

Answer 8

MILSATCOM essential to UK’s strategic and tactical communications infrastructure.

Remove reliance on unreliable local comms facilities.

HQ comms over long distances.

Lower manpower requirements that relay tech.

Larger bandwidth available.

Question 9

What frequency bands do we use for SATCOMs?

Answer 9

UHF | 300MHz - 3GHz

SHF | 3GHz - 30GHz

Question 10

What are the 3 Satellite Segments?

Answer 10

Space (the satellite)

Ground/Earth (any ground terminals, earth stations, mobile terminals and UKMSCS)

Control (integral to both space/ground/earth)

Question 11

What are the 6 Sub-systems in Space?

Answer 11

Antenna
Communication
Thrust (trajectory)
Stabilisation
Electrical Power Generation
Tracking Telemetry/Command

Question 12

What are the Ground Segments?

Answer 12

Fixed high capacity Operational Terminals

Master Control / Coordination Station

Duplicate alternative e.g. maintenance backup

Fixed/Semi-static for UK/Deployed

Mobile/transportable/man-pack tactical terminals

Question 13

What does Control Segment do?

Answer 13

Manage and control facilities to coordinate network

Control satellites / control ground comms terminals

Power balancing for usage and priority

Question 14

Where are the two main UKMSCS locations and which one is the main and backup?

Answer 14

Oakhanger (main)

Colerne (backup)

Question 15

What hazards are involved in SatComs?

Answer 15

RF Hazard (EM radiation)
Deployment (weight etc.)
Electrical (High power area)

Question 16

What is the definition of Electromagnetic Radiation (EMR)?

How does it travel?

Answer 16

Waves of energy (electromagnetic field) as it propagates through any given medium.

Travels in straight lines (LOS).

Question 17

What band of frequencies do SatComs fall under in the electromagnetic spectrum?

Answer 17

Microwave band

Question 18

How does an antenna transmit waves to counter orientation/interference?

Answer 18

Circular polarization (helix shape)

Question 19

What are the advantages of SatComs?

Answer 19

Worldwide Comms
Quick Setup
Versatile (many functions)
Remote Locations

Question 20

What are the disadvantages of SatComs?

Answer 20

Cost
Lifespan (fuel)
Network of Satellites needed (for worldwide comms)
Time required (Planning, Deployment & Deployment)

Question 21

Types of Satellite Networks?

Examples of each?

Answer 21

Complex - more than one satellite e.g. GPS

Simple - 1 One satellite e.g. normal military setup

Question 22

What is the UpLink frequency?

Answer 22

7.9 - 8.4 GHz

Question 23

What is the DownLink frequency?

Answer 23

7.25 - 7.75 GHz

Question 24

What types of Orbits are there, and their sub orbits if any, brief description of each?

Answer 24

Polar - North-South poles (terrain mapping)

Sub-synchronous

• Low earth orbits (LEO) (observations)
• Medium earth orbits (MEO) (GPS)

Synchronous

• Geostationary (Telecoms) (stays in same place)
• Geosynchronous (Weather, Comms, Observations) (figure of 8)

Question 25

How long does a Synchronous Orbit take? What altitude does a Synchronous satellite orbit at? What bean width is required for 3 Satellites at 120° apart to encompass the whole of earth? Does it require any tracking?

Answer 25

23hrs 56min 4s 35.7km or 22.3k miles 17° Minimal/no tracking

Question 26

How do Geostationary and Geosynchronous orbits differ? Tracking?

Answer 26

Geostationary orbits exactly above equator meaning stays in same place. No tracking. Geosynchronous drifts near the equatorial place at an incline, creating figure 8 in sky. Minimal tracking.

Question 27

What are the 4 monitoring and control procedures of a satellite? Brief description?

Answer 27

Beacon (signal coming from satellite) Locking on (Initial communication permission between ground and satellite using beacon to pinpoint location) Tracking (keeping track of satellite with antenna e.g. figure 8 pattern) Monitoring (bit errors, noise, power balancing)

Question 28

What ranges of Spot Beams are there and which do we use?

Answer 28

Global (large range) Regional Wide (1800km radius) Regional Narrow (1350km radius) Theater (600km radius)

Question 29

What does a transponder usually consist of?

Answer 29

Receiving antenna Band pass filter (BPF) Low-Noise Amplifier (LNA) Frequency Translator High power Amplifier (HPA) BPF Transmitting antenna

Question 30

Explorer 700 BGAN Terminal speeds? Wi-fi range?

Answer 30

492 kbps | 100m

Question 31

BGAN - health and safety requirements?

Answer 31

1m safety distance using cordons and signage Only use approved batteries (Thrane & Thrane) Observe marked heat areas

Question 32

What are the major subsystems/equipments in a Transmitting Station System? And what do they consist of/do?

Answer 32

Baseband User -> Multiplexer -> Modem (digital to analogue) -> L-Band signal Tx Up Converter -> X-band -> Solid State Power Amplifier (SSPA) -> BPF Antenna Duplexor -> Waveguide -> Reflector [Freq. Gen Equipment Subsystem -> stable clock -> Multiplexer/Modem]

Question 33

What are the major subsystems/equipments in a Receiving Station System? And what do they consist of/do?

Answer 33

Antenna Reflector -> Waveguide -> Duplexor Rx BPF -> Low-noise Amplifier (LNA) -> Down Converter -> L-band Baseband Modem (analogue to digital) -> Multiplexer -> User [Control and Monitoring - DConv -> BRX -> ACU -> Antenna]

Question 34

List the 7 major subsystems in a typical Satellite Earth Station not including the Users.

Answer 34

``` Baseband Transmitter Receiver FGES (Freq.Gen.Equipment.Subsystem) Antenna Power Monitor & control ```

Question 35

What are the 4 antenna types? And how are they identified?

Answer 35

Cassegrain - Convex "(" shape secondary reflector Gregorian - Concave ")" shape secondary reflector Axial/front-feed - parabolic primary reflector Off-axis/Offset feed - irregular/offset support feed