International Mobile Satellite Organization (IMSO)

Questions and Answers

Why did the ITU grant all countries the right to an orbital slot directly over their territory?

To restrict the use of satellites for military purposes

To promote the development of satellite technology

To allow countries to claim sovereignty over orbital slots

To ensure equal access to space resources (correct)

What is a necessary requirement for installing and operating an earth station or VSAT?

Permission from the local government

A partnership with a satellite operator

A licence from the national telecommunications authority (correct)

Approval from the ITU

What is the purpose of multiple burns during a GEO satellite launch?

To test the satellite's propulsion system

To deploy the satellite's solar panels

To reach the desired orbit (correct)

To communicate with the satellite during launch

What determines the customization of a satellite's payload?

The mission requirements and objectives Signup and view all the answers

What is the estimated cost of launch services for a GEO telecom satellite?

$55-$100 million Signup and view all the answers

What is the main objective of the ITU's orbital slot registration?

To ensure equal access to orbital slots for all countries Signup and view all the answers

Why do some satellites cost as much as $500 million?

Because of the complexity and customization of the satellite's payload Signup and view all the answers

What is the primary benefit of using satellites in communication systems?

Cost advantage independent of distance Signup and view all the answers

What type of satellite uses GPS technology to provide a person's exact location on Earth?

Navigation satellites Signup and view all the answers

What is the transmission of signals to the satellite called?

Uplink Signup and view all the answers

What is the advantage of satellite systems utilizing MEO (medium Earth orbit)?

High capacity and low latency Signup and view all the answers

Why are satellites complementary to cable?

Cables are subject to cuts Signup and view all the answers

What is the transmission of information from the satellite called?

Downlink Signup and view all the answers

What is one of the benefits of using satellites in communication systems?

Not affected by geographical obstructions Signup and view all the answers

Study Notes

Satellite Operators

International Mobile Satellite Organization (IMSO) oversees public satellite safety and security communication services via Inmarsat satellites.
IMSO provides services for maritime safety within the Global Maritime Distress and Safety System (GMDSS), including distress alerting, search and rescue co-ordinating communications, maritime safety information broadcasts, and general communications.

Satellite Services

The commercial satellite industry provides various services, including:
- Voice/Video/Data Communications
- Position Location
- Rural Telephony
- News Gathering/Distribution
- Internet Trunking
- Corporate VSAT Networks
- Tele-Medicine
- Distance-Learning
- Mobile Telephony
- Videoconferencing
- Business Television
- Remote Sensing
- Pipeline Monitoring
- Security & Database Access
- Emergency Services
- Direct-To-Consumer services, including Broadband IP, DTH/DBS Television, Digital Audio Radio, Interactive Entertainment & Games, and Video & Data to handhelds

Technology Trends

Market trends for capacity continue to grow despite fibre deployment.
There is a potential shortage of capacity in some areas due to heavy cutbacks in launches.
Bandwidth is increasing on a per-link basis.
User demands include:
- Smaller terminals
- High throughput
- Enhanced capability
- Constellations
- Responsive space
- Lower costs ($1000 or less)

The Space Segment

A communications satellite has various components, including:
- Propulsion System
- Telemetry, Attitude Control, and Commanding
- Power System/Thermal System
- Solar Arrays
- Receiver Section
- Transponder
- Transmitter Section
- Rx Antennas
- Tx Antenna
Satellite capacity typically ranges from 24 to 72 transponders, with each transponder capable of handling up to 155 Mbps.

Satellite Design

Key aspects of satellite design include:
- Electrical Power
- Station Keeping
- Attitude Control
- Orbital Control
- Thermal Control
Orbital Control involves keeping the satellite stationary with respect to Earth station antennas.

Satellite Orbits

The ITU Member States have established a legal regime for orbital slot registration.
The ITU acknowledged that all countries have an equal right to orbital slots.
Article II of the Outer Space Treaty forbids sovereignty claims over orbital slots.
Countries have rights to an orbital slot directly over their territory.

Building and Launching a Telecommunications Satellite

It takes approximately 3 years to build and launch a GEO telecom satellite.
Satellite payloads are customized for a given mission.
Satellites undergo extensive testing, including mechanical, thermal, noise, and RF tests.
The typical cost of a satellite is 150−150-150−250 million, with some costing up to $500 million.
Launch services and insurance add additional costs (55−55-55−100 million).

Satellite Link Analysis

A 2 Mbps link using QPSK-3/4 modulation has a required bandwidth of 1.67 MHz and an efficiency of 1.20 bps/Hz.
The same link using 8PSK-3/4 modulation has a required bandwidth of 1.11 MHz and an efficiency of 1.80 bps/Hz.
The same link using 8PSK-7/8 modulation has a required bandwidth of 0.95 MHz and an efficiency of 2.10 bps/Hz.

Modcod Selection

Modcod selection is constrained by signal to noise ratio (SNR) at reception.
Higher modulation order requires a higher SNR for demodulation.
SNR is affected by link conditions, available power, satellite performance, antenna size, and modem capabilities.

Satellite Link Budget Analysis

A satellite link budget analysis determines the suitable modcod, required bandwidth, and power.

Efficiency

A good efficiency depends on the specific satellite link analysis.

Satellite Communication Components

A satellite circuit consists of an antenna that transmits/receives and focuses the signal towards/from the satellite.
The satellite receives signals, filters them, converts frequencies, and amplifies them for transmission.