 Hello everyone, welcome to a video lecture on Satellite Earth Station. Myself, K.R. Viradhar, Assistant Professor, Department of Electronics and Telecommunication Engineering, Walsh and Newstop Technology, Salapo. Let us start with the learning outcomes first. At the end of this session, students will be able to illustrate the Satellite Earth Station and its types. Before discussing what is an Earth Station, the various subsystems of satellite communications are. Earth Station are also called the Earth Segment, Space Segment and the link between Earth and the Space Segment. In this topic, I am going to discuss about part of the Earth Segment which is called the Earth Station. Now look for definition of or what is an Earth Station is. Any transmitting or receiving system which sends or receives signal to and from satellite. That means we can transmit the signal from Earth Station to the satellite and also it receives the signals from the satellite. Earth Station is a significant element in satellite communication network. That means Earth Station plays very important role in satellite communication system. The function of an Earth Station is to receive from or transmit information to the satellite. That means in the uplink, the Earth Station transmit the information from Earth Station to the satellite during the uplink. As in the downlink, the satellite will transmit back to the Earth Station. The design of an Earth Station configuration depends upon many factors and its location. The various factors of designing the Earth Stations are may be transmitted power or transmitting power, receiving power and size of the antenna and noise to temperature ratio and noise in introducing the network etc. And location of Earth Stations are may be it is an Earth on the surface of Earth or it may be in the ship of sea or it may be an airborne. Then question arises what are the major subsystems of Earth Station. Pause the video for a 2 minutes and write your answer. I think 2 minutes over major subsystems of the Earth Stations are transmitter, receiver, antenna and tracking equipment. Transmitter is used to transmit the signals from the Earth Station to the satellite and receiver is used to receive the signal from the satellite to the Earth Station. Antenna which is used to radiate the electromagnetic waves and also that is received the electromagnetic waves transmitted from the satellite. The tracking equipment which is used to alter the position of the antenna up, down, right, left etc. depends on the position of the satellite. This pictorial representation of satellite communication system consists of there are Earth Stations that is one is transmitting Earth Station, another one is receiving Earth Station and there is a satellite here. Then the signal which is transmitted from Earth Station to the satellites is called the uplink and the received signal or the signal which is in issued from the satellite to the Earth Station is called the downlink. Here satellite acts as a completely repeater which takes the signals and amplify, remove noise and retransmit again. So can it not possible directly to do from transmitting Earth Station to receiving Earth Station? This is not possible because for a longer distance these two antennas are not comes under direct line of sight. That is why here satellite acts as a repeater which will take the signal from the transmitting Earth Station and so process the data and retransmit again to the receiving Earth Station. Then look for the block diagram of Earth Station. The Earth Station mainly consists of transmitter, receiver and antenna system and the tracking subsystem. So whatever the at the top side you can see that is encoder, modulator, upconverter, high power amplifier these that is blocks comes under the transmitter whereas down you can see this is nothing but a reverse process of whatever the transmitter has done that is called the receiver. There is an antenna system which can transmit or radiate the electromagnetic waves and also it issues the electromagnetic waves from the satellite and there is a tracking system, tracking system is used to alter the position of the antenna at their station depends on the position of the satellite. There is a terrestrial network and baseband equipment. This flow and what are its functions we shall see these things. Let us see first transmitter. The digital information enters at baseband equipment that is BBE from terrestrial network. Here the information which is available from the user to be transmitted will come from the terrestrial network to the baseband equipment. Encoder which includes that is no error correcting bits which is used to minimize the bit error rate present in the signal. So in satellite communication the intermediate frequencies are either 70 megahertz by a transponder having bandwidth of 36 megahertz or 140 megahertz by a transponder having bandwidth of 72 megahertz these two can be used one at a time. Up converter performs the frequency conversion of modulated signal to higher frequency. Generally the modulated signal which is having a radio frequency but it is not that much higher frequency which can transmit for longer distance. We need to alter the frequency or we need to increase the frequency in the at the transmitter so that it can reach to the receiver safely and perfectly that will be done by this up converter block. This signal which is coming out from the up converter will be amplified by using high power amplifier because the frequency is RF signal which is having very high frequency we need to use the high power amplifier to amplify before radiating or transmitting the signal to the base. The earth station antenna transmit this signals are earth station antenna radiates this signal then comes under the receiver. The earth station antenna receives the volume signal coming from the satellite. So the signal which is received is RF signal it is having very high frequency but it is a low strength signal that is why we need to have or we need to amplify that signal that will be done by low noise amplifier. Low noise amplifier performs the amplification of the RF signal is having a high frequency. RF signal can be down connected to IF value whatever the in the transmitter we have done that is in the up converted here we need to doubt convert into IF value because the RF signal cannot be directly demodulated that is why we need to convert down that frequency higher frequency into medium frequency to a IF value or intermediate frequency value. The function of decoder is just opposite to that of encoder. So it produces an error free binary information by removing error correction bits. This binary information is given to baseband equipment for further processing and then delivers to the terrestrial network. This as transmitter we have done that is taken from terrestrial network and placed it in a broadband equipment. Here the signal which is coming from broadband equipment will be processed and delivers to the terrestrial network. Then earth station antenna the major parts of the earth station antenna are feed system and antenna reflector. So the feed system is used here to separate or we can transmit the that is signal and also receive the signal simultaneously will be done by this feed system. Then the antenna reflector antenna reflector for gain can be increased or high gain signals will be produced this antenna reflector. These two parts combinedly together radiates or receives electromagnetic waves. Then last is tracking system. The tracking system present earth station performs mainly two functions that is satellite acquisition and the satellite tracking. That means antenna which is that is revolve around the earth is not in a fixed orbit it will be moving and earth is also moving because the position of the antenna at the earth station should have to point towards the satellite that is why we need to move the earth station antenna towards the towards pointing to the satellite that will be done by this tracking subsystem. There are different ways we can do this tracking system that is automatic tracking manual tracking and the program tracking. So among these three tracking system program tracking is accurate one we can do automatically. So different types of earth station the earth station can be classified on off depends on the size of the antenna and the service provided and also we another method is and there it says also you can classify the earth stations depends on the size and the service provided there are three types of earth station that is fixed satellite service earth station. Second one is broadcast satellite service earth station third one is mobile satellite service earth station. So depends on the usage how we are going to define that is classify the earth stations are single function stations, gateway stations and the teleports. These things we shall see or discuss later. These are the references I have considered to prepare the above PPT thank you.