In order to shape telecommunication in the present day, satellites are considered one of the crucial parts of the entire communication system. The presence of artificial satellites helps in receiving a fast and easy transmission of both kinds of signals such as analogue and digital. Focusing on this particular parameter of telecommunication the parent tutorial will discuss satellite communication in a brief manner along with defining the active and passive satellites.
Figure 1: Satellite communication
Satellite communication can be defined as the particular communication that is established with the help of different stations present on the earth's surface and satellites in space. The entire communication happens on the basis of an electromagnetic spectrum (Yan et al. 2019). In simpler terms, it can be stated that while the establishment of communications between two or more ground-based units if artificial satellites are used, the communication will be considered satellite communication.
To propagate the ground wave: This specific type of propagation of radio wave allows getting the transmission of a signal with up to 30 MHz frequency from one end to another. Using the layer of the troposphere of the earth’s atmosphere, the artificial satellites present in the space or orbit of the earth help to propagate such wave transmission.
To propagate sky waves: These specific types of radio waves are generally used in order to transmit a specific signal that falls in the range of up to 40MHz. The main difference that is shared with ground wave is that such radio waves can be propagated by getting refracted through the ionospheric layer (An et al. 2018). In order to make this propagation stable, the distance that needs to be maintained between the ground and the space station is 1500 km otherwise the activation of the satellite communication cannot be activated successfully.
Figure 2: Satellite communication system
In order to understand in a very basic manner, the first step that is taken for activating satellite-based communication is receiving a signal from a ground-based station by satellite. Aftermath, the artificial satellite performs amplification and conducts the required processing in order to retransmit it towards one or multiple stations that are earth-based which receive the incoming signals (Lalbakhsh et al. 2020). In this process, it needs to be kept in mind that the signals exchanged between two stations based on the earth are neither transmitted nor originated at the satellite that is present in the earth’s orbit in space. In order to establish satellite communication, two major components are required to be in the communication structures that are the space segment and the earth segment.
The satellites that are used to transmit or propagate away from one earth-based station to another earth-based station are referred to as positive satellites (Khawaja et al. 2018). In a simpler diction, if a hydrogen balloon is lifted into the atmosphere by attaching a metallic layer upon its surface, such kind of balloon will be able to transmit or reflect microwave signals, technically will be recognised as passive satellites.
The active satellites, unlike passive satellites, after receiving a signal from an earth-based station, amplify it and retransmit it to another earth-based station. In the case of active satellites, the signal strength is excellent. Where passive satellites are considered the earliest medium of building satellite communication, active satellites are considered the modern mediums of building satellite communication with high signal strength.
Satellite communication is classified into two distinct categories as follows:
One-way satellite communication: In such communication, the communication is generally established between two earth stations using the artificial satellite present in the earth’s orbit where the transmitted signal is unidirectional.
Two-way satellite communication: Such kind of communication is established based on point-to-point connectivity, within two particular earth stations and two uplinks and downlinks happen between these two earth stations.
Figure 3: Satellite Communication Block Diagram
Advantages: The instalments of circuits are easy along with excellent elasticity which helps to cover every corner of the earth to build a user-controllable network.
Disadvantages: The expenditure at the initial stage is extensive. In addition, the chances of appearing blockage in frequencies are considerably high. Additionally, the interference and propagation are higher and complex to manage easily.
The tutorial has explained the concept of satellite communication along with explaining the entire process of satellite communication. Along with the representation of a diagram of such communication, the tutorial further included the advantages and disadvantages of satellite communication. It has been seen that the initial expenditure for the establishment of such communication is expensive but it offers the user full control. Moreover, satellite communication is categorised in two distinct classifications, one-way and two-way communication which are directed through three stages, uplink, transponders and downlink.
Q1. What are the two crucial components of satellite communication?
Ans. Two main components of satellite communication are the space segment and the ground segment, and the space segment. The ground segment comprises the ancillary equipment and either mobile or fixed transmission and reception whereas, the satellite itself is considered a space segment.
Q2. What are the applications of satellite communication?
Ans. In order to establish long-distance telephony-related applications, satellite communications are applied. The other application of satellite communication involves remote sensing, meteorological surveys and many more.
Q3. What was the name of the first artificial satellite in the world?
Ans. According to the information, the name of the world’s first artificial satellite was Sputnik 1. The Soviet Union launched it on 4 October 1957.
Q4. What is radio propagation?
Ans. The specific behaviour of the radio waves propagation to another place from one place through various parts of the atmosphere is recognised as radio propagation.
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