Satellite communications system

Satellite

Satellite communication started in 1971. A satellite called small Yunik was launched by USSR in October. It only had a Beacon trasmeter which was not sufficient for communication. Satellites were transported into the orbit by powerful rockets. Later, large balloons were used as passive reflectors for communication in the satellite. The first communication satellite was launched in July 1962, named Telstar-I. In May 1963, a satellite named Telstar-II was launched. 

In a short time, communication with mobile subscribers was also provided by the satellite. Water vessels and airplanes were being supported by the Inmarset Satellite. Satellite communication has become a useful communication medium of human life due to the various important and useful services provided by the satellite, which is used in everyday tasks. The first Intelsat-1 satellite was launched by the INTEL organization in April 1965. GEO satellite communication started after the launch of this satellite. In less than ten years, Intelsat started launching self-sufficient satellites and in 25 years it has launched about 100 satellites.

Satellite communications system

A basic satellite communication system is present in space that links to more than one Earth station located on Earth. Different antenna is used at the transmitting and receiving end of the satellite. Earth stations and consumers are the main components in addition to the satellite in the system. The connection between the subscriber and the earth station is through the terrestrial system.

Basic satellite communications system

The following are the major components used in the SATELLITE COMMUNICATION SYSTEM.

1. USER

The consumer is an important source and receiver of information for transmission of information through satellite.  On the transmitting side, the consumer generates a baseband signal that reaches the earth station via the terrestrial system.  The baseband bearing signal is received by the Earth station on the receiving side.

2. TERRESTRIAL SIDE SYSTEM

This Earth acts as a link between the station and the consumer. The terrestrial system is used when the consumer is at a greater distance from the station. The telephone switch is a terrestrial network.

3. EARTH STATION

The baseband transmitted by the consumer is received at SINLCO Earth station side. After transmitting this received information via satellite, a process of re-transmit takes place in which a nomination is received from the satellite at the receiving alert station. The receive signal is processed and sent to the consumer through the test medium.

4. SATELLITE

There is a large repeater for satellite space. It moves in an arranged orbit around the Earth in space. The satellite receives the information and re-amplifies it and transmits it to other receiving stations.

The satellite is an artificial object that is placed in the orbit of the earth

TYPE OF ORBIT:-

LEO - Lower earth orbit
MEO - Medium earth orbit
GEO - Geostationary earth orbit
HEO - Highly elliptical orbit

1. LEO - Lower earth orbit

• The transmission power of the antenna is low
• The orbital experiment in Leo is 84–127 min.
• The satellites of this orbit live for 5 to 8 years.

2. MEO - Medium earth orbit

• It is 500 to 1500 km from the earth.
• Orbilal Priode 2-24 is of Roures.

Application

   GPS (Global positing system) Communication

3. GEO - Geostationary earth orbit

• It is 36000 km from Earth
• orbilal paricode is 24 hours
• The life of a GEO satellite is 15 years.
• An entire earth is covered by 3 GEO satellite

4.HEO -Highly elliptical orbit

• It is more than 36000 km from the suprface of earth
• orbital prieode is more than 24 hours
• It is used in military applications.

link model of satellite System

The satellite link model mainly consists of two earth stations and one satellite. Transmitting the means by which the information signal is transmitted to the satellite Earth station says.

• Uplink
• Downlink 
• Satellite transponder 
• Crosslink

1.Uplink 

The link in the signal space that is transmitted to the satellite by the transmitting earth station is called an uplink. The signal is transmitted from the Earth station to the satellite at a fixed frequency that can easily cross the ionosphere in space.  This frequency is called uplink frequency.  6 GHz frequencies are commonly used for uplinking in satellite communication systems.

2. Downlink 

The path followed by the transmitted signal from the satellite to the receiving earth station is called downlink and this signal is called downlinked.  The frequency at which the downlink signal is transmitted by the satellite is called downlink frequency.  Downlink frequencies in satellite communication are typically 4 GHz.  S

3. Satellite transponder

The satellite transponder is usually a part of the satellite communication subscription system. The main function of the traceponder in the satellite communication list is to receive the uplink carrier signal and to amplify the received signal. ; With the help of a receiver, this signal is converted from uplink frequency to downlink frequency and transmitted to the receiving earth station. To increase the power level of the receiving signal to the appropriate value, the signal received by theinder is applied, so that the mineral can reach the receiving earth station.

                   Pinder, along with Palot, is essential for communication. Satellite communication is the main part of the Karibita membership system, supported.

Front and electronics block diagram used in satellite traceponders

RF FRONT END

The front end electronics used in satellite transponders are used by the desponder to receive the uplink carrier, change the frequency of the carrier signal, or amplify the signal's power level to a reasonable value. The above mentioned satellite is the single-channel, supounder. Unun in a channelized repeater, the supporter is called a channel of that daily replicated. Repeaters used in modern satellite communication systems use more than one channel, that is, multichannel repeaters are used in modern systems.

4. Crosslink

Communication between two satellites in a satellite requires radio links called crosslinks. A crosslink refers to the Intersatellite Link (ISL) between two orbiting satellites. Intersatellite link is a communication link and the following are the disadvantages of this communication link

(A) Spaceborne in transmitting and receiving systems,

(B) limited operation of low P, power and low g/ T ° values.

Compoundsets of longer length links require that the narrow transmit beam be restored for higher constriction with increased EIRP. The nerobime commonly assumes restoring higher carrier frequencies for the satellite antenna size const. Satellite cross links are designed in K-band (20–30 GHz) and EHF (60 GHz).