Description

An artificial satellite that uses a transponder to relay and amplify radio telecommunication signals is known as a communications satellite. It opens a channel for communication between a source transmitter and a receiver in different parts of the world. Television, telephone, radio, internet, and military applications all make use of communications satellites. There will be 2,224 communications satellites in Earth orbit on January 1, 2021. The majority of communications satellites are in geostationary orbits, which appear to be stationary at the same location in the sky and are 22,300 miles (35,900 kilometres) above the equator. As a result, ground station satellite dish antennas do not need to move to follow the satellite because they can aim permanently at that location.

Radio and Microwave Frequencies

The Earth's curvature prevents the high-frequency radio waves used in telecommunications links from traveling straight ahead. The signal from communications satellites is transmitted around the Earth's arc to enable communication between geographically distant points. Radio and microwave frequencies are utilized by communications satellites in great detail. International organizations have rules about which frequency ranges, or "bands," certain organizations can use to avoid signal interference. There are two primary types of communications satellites: Passive and active. This allocation of bands reduces the likelihood of signal interference. Only the signal coming from the source, in the direction of the receiver, is reflected by passive satellites. Only a very small amount of the transmitted energy actually reaches the receiver with passive satellites because the reflected signal is not amplified at the satellite. The radio signal is attenuated by free-space path loss because the satellite is so high above Earth consequently the signal received on earth is extremely weak. On the other hand, active satellites amplify the received signal before retransmitting it to the ground receiver. Passive satellites were the first communications satellites, but they are no longer used much.

A project known as communication moon relay resulted from the electrical intelligence gathering work that was started in 1951 at the United States Naval Research Laboratory. The creation of the longest communications circuit in human history, with the moon, earth's natural satellite, serving as a passive relay, was the ultimate objective of this project. Military planners had long shown a lot of interest in secure and dependable communications lines as a tactical necessity. Telstar was the first active, direct relay communications commercial satellite and the first transatlantic transmission of television signals.

Communications Satellite Corporation

One more detached transfer try principally expected for military correspondences designs was task west passage, which was driven by Massachusetts Organization of Innovation's Lincoln Laboratory. After an underlying disappointment in 1961, a send-off on 9 May 1963 scattered 350 million copper needle dipoles to make a latent reflecting belt. The project was able to successfully experiment and communicate using frequencies in the SHF X band spectrum, despite the fact that only about half of the dipoles were properly separated. Hughes Aircraft Company's Syncom 2 which was launched on July 26, 1963, was an immediate precursor to the geostationary satellites. The first communications satellite to be in a geosynchronous orbit was Syncom 2. Its successor, Syncom 3, launched on July 19, 1964, was the first geostationary communications satellite. Although it travelled around the earth once per day at a constant speed, special tracking equipment was required due to its continued northâ??south motion. The Lincoln Experimental Satellite program, which was also carried out by the Lincoln Laboratory on behalf of the United States Department of defence was a direct extension of the passive experiments of Project West Ford. The LES-1 active communications satellite was launched on February 11, 1965, to investigate the viability of active solid-state X band long-range military communications. Syncom 3's geosynchronous orbit made it appear to be stationary from the ground. As part of this series, nine satellites were launched between 1965 and 1976. International commercial satellite projects In the United States the Communications Satellite Corporation (CSC) private corporation was established in 1962. Over the next two years, international negotiations resulted in the Intelsat Agreements, which in turn led to the launch of Intelsat 1, also known as Early Bird, on April 6, 1965. This was the first commercial communications satellite to be placed in geosynchronous orbit. Subs When Intelsat was launched the United States was the only launch source outside of the Soviet Union that did not participate in the Intelsat agreements. The Soviet Union launched its first communications satellite on April 23, 1965, as part of the Molniya program. This program was also unique at the time for its use of what was then known as the Molniya orbit, which describes a highly elliptical orbit with two high apogees daily over the northern hemisphere a Low Earth Orbit (LEO) typically has a period time to revolve around the earth of approximately 90 minutes and is a circular orbit approximately 160 to 2,000 kilometres (99 to 1,243 mi) above the earth's surface. Because of their low altitude, these satellites are only visible from within a radius of approximately 1,000 kilometres from the sub-satellite point. This orbit also provides a longer dwell time over Canadian territory and Russian territory at higher latitude additionally, satellites in low earth orbit rapidly alter their position in relation to the ground. So in any event, for neighborhood applications, many satellites are required on the off chance that the mission requires continuous network.

Due to their proximity to the ground low-Earth-orbiting satellites do not require as much signal strength as geostationary satellites do signal strength decreases as the square of the distance from the source, so the effect is significant. As a result, there is a trade-off between the cost of the satellites and the number of them. In addition, the ground and onboard equipment required to support the two kinds of missions differ significantly.