Day 2: Sat Networks

Question 1

System of communication satellites in space to facilitate various forms of communication (voice, data, video)

Answer 1

Satellite Networks

Question 2

What are the four applications of satellite networks?

Answer 2

• Telecommunications
• Broadcasting
• Internet
• GPS

Question 3

Relies on stationary ground equipment at predetermined locations; point-to-point and point-to-multipoint comms (ex=VSATS)

Answer 3

Fixed Satellite Service (FSS)

Question 4

Distribution of TV, radio, etc via satellite to a wide audience (fan-out); stands out for high transmission power

Answer 4

Broadcasting Satellite Service/Direct Broadcast Service (BSS/DBS)

Question 5

Employs transportable receiver and transmitter equipment; provides voice, data, and messaging services to land, maritime, remote environments

Answer 5

Mobile Satellite Services (MSS)

Question 6

Fixed Satellite Service (FSS) Common Bands

Answer 6

C, Ku, Ka

Question 7

Broadcasting Satellite Service/Direct Broadcast Service (BSS/DBS) Common Bands

Answer 7

C, Ku, Ka

Question 8

Mobile Satellite Services (MSS) Common Bands

Answer 8

L, S, C

Question 9

VSAT stands for?

Answer 9

Very Small Aperture Terminal

Question 10

VSATs utilize ______ dish antennas to transmit and receive data via satellite

Answer 10

Small

Question 11

Enables _______ comms between ______ _________ and a _______ ___, typically located at a network operations center or data center

Answer 11

two-way
remote locations
central hub

Question 12

What kind of solution is for connecting remote locations to broader comm infrastructure?

Answer 12

Versatile and reliable

Question 13

What are VSAT applications?

Answer 13

• Internet
• Telecomms
• Broadcasting
• Military

Question 14

Biggest advantages of VSAT

Answer 14

Easy to install and inexpensive to operate

Question 15

VSAT Common Bands

Answer 15

C, Ku, Ka

Question 16

Wider coverage (suitable for global comms); less signal degradation due to rain/atmosphere

Answer 16

C-Band Advantage

Question 17

Limited BW availability compared to higher frequency bands, lower data transmission rates

Answer 17

C-Band Disadvantage

Question 18

Higher data transmission rates compared to C, so suitable for higher BW applications

Answer 18

Ku-Band Advantage

Question 19

More susceptible to rain attenuation, smaller coverage area because more susceptible to atm absorption

Answer 19

Ku-Band Disadvantage

Question 20

Higher bandwidth, enabling very high data transmission rates; allows for the use of smaller antennas, making it more suitable for mobile and broadband applications

Answer 20

Ka-Band Advantage

Question 21

Highly susceptible to rain attenuation, and easily absorbed by atmospheric gases, limiting their effective range and coverage area

Answer 21

Ka-Band Disadvantage

Question 22

What are the 4 segments of VSAT network?

Answer 22

• Ground Station
• RF Links
• Satellite
• Users

Question 23

Requires constant communication with VSAT ground station to pass data between nodes and cannot communicate directly with other nodes

Answer 23

Star

Question 24

Nodes can communicate directly with other nodes within the VSAT network but still require a master control station to ensure timing and access to the network is maintained

Answer 24

Mesh

Question 25

**Mix of star and mesh** that allows the hub to send information to the remote components

Answer 25

Hybrid

Question 26

What is AUPC?

Answer 26

Automatic Uplink Power Control

Question 27

What is the first step of Automatic Uplink Power Control (AUPC)?

Answer 27

Remote station receives signal and demodulates

Question 28

What is the second and third step of Automatic Uplink Power Control (AUPC)?

Answer 28

Remote station **demodulator identifies Eb/No** beyond lower threshold, and **Requests** an **increase** in **power** using reserved bytes in overhead structure

Question 29

What is the fourth step of Automatic Uplink Power Control (AUPC)?

Answer 29

Local MODEM **adjusts output power level to** attempt to **maintain the Eb/No** at the remote MODEM

Question 30

What is the ALC?

Answer 30

Automatic Leveling Control

Question 31

What does the Automatic Leveling Control (ALC) do?

Answer 31

**Auto**matically **changes** the **power in** the individual **channels** on the transponder in the channelizer to **overcome interference**

Question 32

When the receive signal level drops below a certain SNR, the individual downlink or uplink subchannel will boost power

Answer 32

Automatic Leveling Control (ALC)

Question 33

If the power is too high, what will lower the power to meet the average SNR threshold?

Answer 33

Automatic Leveling Control (ALC)

Question 34

What is the ACM?

Answer 34

Adaptive Code Modulation

Question 35

When the signal reaches the receiving modem and drops below a certain threshold, the receiving modem will send a burst to the transmitting modem to change to a more **robust MODCOD** to mitigate interference

Answer 35

Adaptive Code Modulation (ACM)

Question 36

What is MODCOD?

Answer 36

* Mod - Modulation Scheme * COD - FEC