Satellite Communication

Satellite:

In Satellite Communication, a satellite is an orbiting object that travels around a larger object, such as a planet. Hundreds of artificial satellites additionally natural ones, such as the Moon, orbit, and the planet Earth.

A satellite is a man-made object sent into orbit around a celestial body, such as the sun, moon, or Earth. Weather satellites and telecommunication satellites are two instances.

ref: isro

Why Satellite?

Because of the curvature of the Earth, microwave signals travel in a straight line on a sphere, but they need a lot of repeaters to connect two very far apart places on opposite sides of the sphere.
Two continents can be connected by a single satellite using a single repeater.

A satellite is a repeater that receives a signal at one frequency from Earth, amplifies it, and sends it back at another frequency.

Earth Station:

A basic satellite communication link consists of two Earth stations. One sends a signal known as sending ES to a satellite.
The other receives the signal known as receiving ES from the satellite.

Up-Link and Down-Link:

Up-link is the communication channel used to send ES data to a satellite.
Downlink refers to the communication channel from the satellite to the receiving ES.

History of Satellites:

WW II promoted the advancement of two important technologies.
Communication via microwaves
Missile technology – Soviet Sputnik I, the first artificial satellite, was launched on October 4, 1957, and it had a beacon and telemetry for 21 days.
Tx. Explorer I – January 1958 – United States – Telemetry orders – five months
Score: December 1958 – United States – initial voice communications – President’s speech
ECHO I is a “balloon” satellite with a metalized satellite surface, and passive reflectors, and The ECHO II courier from 1960 stores magnetic tape for later transmission.

First Commercial Satellite: INTELSAT (1965)

Communication satellite Intelsat I – EarlyBird, 34.5 kg, GEO, covering the US and Europe
four years of operation (deactivated in 1969)
originating in Cape Canaveral
240 voices and one TV channel might be handled.
owned by 52 countries’ Intelsat
International satellite company ComSAT is branching out across several countries with Intelsat.

What is Satellite Communication?

The satellite aids in the movement of signals between the sender and the recipient in satellite communication. In this process, a modulated microwave beam is transmitted towards the satellite. The signal is then amplified by the satellite and retransmitted to the receiving antenna on Earth. Thus, all of the signal transfer takes place in space. So, satellite/space communication characterizes this kind of communication.

Basic Satellite System:

1. Space Segment

2. Ground Segment.

The space segment consists of Satellites and Communication Links.

The Ground Segment consists of the Earth Station and User terminals.

Frequencies for Satellite Communication:

L-Band: utilized by MSS, 1 to 2 GHz
S-Band: NASA, MSS, and deep space research use 2 to 4 GHz
C-Band: used by FSS, 4 to 8 GHz
X-Band: 8 to 12.5 GHz, utilized by FSS and in terrestrial imaging, such as satellites for weather and military purposes.
Ku-Band: utilized by the FSS and BSS (DBS); 12.5 to 18 GHz
K-Band: 18 to 26.5 GHz; FSS and BSS utilize it
Ka-Band: 26.5–40 GHz; FSS utilizes this band

Advantages of Satellite Communication:

Satellites have a significantly wider coverage area compared to terrestrial systems.
A satellite’s transmission cost is unaffected by distance from the coverage area’s center.
Extremely accurate communication is possible between satellites.
The use of higher bandwidths is possible.
Quick establishment of the ground network
Minimal cost for each additional site
consistent qualities of service
Complete assistance from a single supplier
narrow margin of fading (3dB)
Numerous uses

Disadvantages of Satellite Communication:

Satellite launches into orbit are expensive.
The available satellite bandwidth is steadily running out.
When compared to terrestrial communication, satellite communication has longer propagation latency.
A brief lifespan of up to 15 years
Component redundancy
Interference and noise

Satellite System:

One or more satellites make up a satellite system.
An earth-based station that manages the system’s User-new Earth Stations and offers interface capabilities for terrestrial communications traffic for the Transmitter and Receiver.

How a Satellite Works?

The centrifugal force of the rotating satellite balances the gravitational pull (centripetal) of the earth, allowing the satellite to remain in orbit.
One Earth Station transmits the signals to the satellite at the up-link frequency.
The signal is processed by the satellite transponder and sent back to Earth at a lower frequency known as the downlink frequency.

Active Satellites: These include processing, switching, demodulation, frequency translation, and power amplification.

Passive Satellites: Transponder Passive Satellites are a block that connects two stations across space; they do not have on-board processing and are not ideal for communication. Possessive satellites use little power and are inexpensive.

Satellite Repeater:

A satellite also known as a microwave repeater, receives uplink broadcasts and converts them into downlink transmissions by filtering, amplifying, processing, and translating frequencies.
To avoid oscillation with the satellite amplifier and to enable simultaneous Transmitter and Receiver at separate frequencies via the Multiplexer, Uplink, and Downlink are separated in frequency.
Lower frequency bands are utilized in the downlink to take advantage of reduced atmospheric losses, allowing for lower satellite power requirements.
Reduce interference from neighboring channels, ISI, and group delay distortion via channel filters.
Huge gains at low noise – High power amplifiers (TWTAs) and low noise amplifiers (FETs).

TYPES OF SATELLITES:

Major Problems for Satellites:

1. Positioning in Orbit

2. Stability

3. Power

4. Communications

5. Harsh Environment

Applications of Satellite

1. Broadcasting and Television: Satellites enable the transmission of television signals to vast geographical areas, including remote and underserved regions. This ensures wider access to news, entertainment, and educational content.

2. Internet and Broadband Connectivity: Satellite internet provides broadband access to areas where terrestrial infrastructure is limited or unavailable. This is crucial for bridging the digital divide and connecting remote communities.

3. Telecommunication and Telephony: Satellite communication facilitates long-distance phone calls, especially for international and maritime communication. It also supports mobile networks in remote regions.

4. Navigation and Positioning (GPS): The Global Positioning System (GPS) relies on satellites to provide accurate location and timing information. This technology is essential for navigation, mapping, surveying, and location-based services.

5. Disaster Management and Emergency Response: Satellites play a vital role in disaster management by providing communication links when terrestrial networks are damaged. They also support remote sensing and data collection for disaster assessment and relief efforts.

1. What is satellite communication and how does it work?

Satellite communication involves transmitting and receiving signals between Earth-based stations and satellites orbiting the planet. These signals carry voice, video, and data, enabling long-distance communication and broadcasting.

2. What are the different types of satellite communication?

Satellite communication systems vary based on orbit type (geostationary, medium-Earth orbit, low-Earth orbit), frequency band, and purpose. Common types include fixed satellite services (FSS), broadcast satellite services (BSS), and mobile satellite services (MSS).

3. What are the advantages and disadvantages of satellite communication?

Advantages include wide coverage, reliable long-distance communication, and independence from terrestrial infrastructure. Disadvantages can involve higher costs, signal latency, and susceptibility to weather interference.

4. What are the applications of satellite communication?

Satellite communication is used for broadcasting (TV, radio), internet connectivity, telephony, navigation (GPS), weather forecasting, disaster management, military applications, and more.

5. What is the future of satellite communication?

The future of satellite communication looks promising with advancements in technology, such as low-Earth orbit (LEO) constellations, high-throughput satellites (HTS), and increased affordability, leading to faster speeds, lower latency, and broader accessibility.