A communication satellite is an R.F (Radio Frequency) repeater. The frequency ranges or bands are identified by letters: (in order from low to high frequency) L-, S-, C -, X-, Ku -, Ka -, and V-bands. Kepler’s 3rd law states that, “The square of the periodic time of the orbit is proportional to the cube of the mean distance between the two bodies.”, Where $\frac{4\pi ^{2}}{GM}$ is the proportionality constant (according to Newtonian Mechanics), Where μ = the earth’s geocentric gravitational constant, i.e. Satellite Communication 05/02/14 RTTC SATCOM 20 Kinds of Communication Satellites depends on type of orbit and freq. The orbital functioning of satellites is calculated with the help of these Kepler’s laws. Basic Concepts of Satellite Communication Telecommunications make use of satellites for larger distance communication which revolves around the earth in elliptical orbits. But it appears stationary when observed from the Earth. This translates to improved signal strength at the receiving end. In this communication, electromagnetic waves are used as carrier signals. Basics of Satellite Communications: As of 1 August 2020, there are 2,787 … In Internet applications such as providing Internet connection for data transfer, GPS applications, Internet surfing, etc. Satellite Communication Basics March 20, 2021 XT-11 Bluetooth Earphone Magnetic Wireless Sports Headset Bass Music Earbuds Mic for Mobile Phones and More Devices A satellite communications (satcom) system maybe looked at as comprising of three parts “space segment”, the “ground segment” and the transmission medium (the space between the Earth and the satellite) The Space Segment1/6 • A telecommunications satellite comprises: A Geo-Synchronous Earth Orbit (GEO) satellite is one which is placed at an altitude of 22,300 miles above the Earth. Μ = 3.986005 × 1014 m3/sec2, $$1 = \left ( \frac{2\pi}{T} \right )^{2}\frac{a^{3}}{\mu}$$, $$1 = n^{2}\frac{a^{3}}{\mu}\:\:\:\Rightarrow \:\:\:a^{3} = \frac{\mu}{n^{2}}$$, Where n = the mean motion of the satellite in radians per second. POWER A communication satellite’s primary source of power is its solar array. This orbit can be tilted at the poles of the earth. A satellite, when it revolves around the earth, undergoes a pulling force from the earth which is the gravitational force. The most common use for satellites in this region is for navigation, communication, and geodetic/space environment science. These signals carry the information such as voice, audio, video or any other data between ground and space and vice-versa. Conventional Satcoms. A typical satellite link involves the transmission or uplinking of a signal from an Earth station to a satellite. Also, it experiences some pulling force from the sun and the moon. Introduction to Satellite Communication. Types of Satellite Communication. This relatively short distance reduces transmission delay to only 0.05 seconds. It can be understood by taking a look at the following figure. Batteries are used as back up and during times of eclipse, which is when the satellite is in the earth’s shadow and it is unable to utilize the sun for energy. 1 Satellite Communications Basics Goal: Through lecture, presentation and visual di splay each learner will be able to understand and explain how Satellite Communication operates overall and within an iDirect network. But here this repeater works as a transponder, which changes the frequency band of the transmitted signal, from the received one. Fixed Satellite . Satellite communication finds its applications in the following areas −. Geo-Stationary Earth Orbit Satellites are used for weather forecasting, satellite TV, satellite radio and other types of global communications. The space system includes Satellite. natural laws that control the movement of satellites. The satellite-communication can be classified into three types which include the following. Satellite system consist of the following systems. •Satellite payloads are customized for a given mission. This orbit is synchronized with a side real day (i.e., 23hours 56minutes). These signals carry the information such as voice, audio, video or … The orientation of the satellite in its orbit depends upon the three laws called as Kepler’s laws. Satellite bandwidth is gradually becoming used up. These are based on Kepler's laws 1.The orbit plane of any earth satellite must bisect the Earth centrally. 1). Satellite Basics Satellites provide businesses with a flexible, universal, reliable, and quickly deployable means to address a wide range of communications needs. Satellite is powerful long distance and point-to multipoint communication system. So, a satellite has to balance these two forces to keep itself in its orbit. satellite Relay satellite Relay satellite Sensor satellite Sensor satellite Crossover or Intersatellite links Mission data Launch phase TT&C TT&C Satellite Ground station TT&C Tracking, Telemetry and Control The communications architecture consists of satellites and ground stations interconnected with communications links. Since the signal is travelling a shorter distance to and from the satellite, there is less transmission delay. SATCOM (satellite communications) technologies have accomplished incredible breakthrough efficiencies and increases in performance in half a century.SATCOM Training or Satellite Communications Training Course with Hands-On Exercises (Online, Onsite and Online Live)Satellite Communications Training Workshop course focuses on basics of satellite communications … A satellite communication system can be broadly divided into two segments, a ground segment and a space-segment. If communication takes place between any two earth stations through a satellite, then it is called as satellite communication. Centrifugal force − The force that tends to push an object moving in a trajectory path, away from its position is called as centrifugal force. Satellite Orbits Frequency Bands There are four radio frequency bands that communication and military satellites operate within: C band uplink 5.925-6.425 GHz; downlink 3.7-4.2 GHz The C band is primarily used for voice and data communications as well as backhauling. There will be a huge number of earth stations to handle the transferring and receive process. Arrays of solar cells convert sunlight to electrical energy. MEOs operates in the frequency range of 2 GHz and above. Centripetal force − The force that tends to draw an object moving in a trajectory path, towards itself is called as centripetal force. Because the satellite is transmitting a signal as it movesacross the sky, you will have to work around the Doppler Effect. A repeater is a circuit which increases the strength of the signal it receives and retransmits it. If communication takes place between any two earth stations through a satellite, then it is called as satellite communication. The higher frequencies associated with Mega-LEOs translates into more information carrying capacity and yields to the capability of real-time, low delay video transmission scheme. The first man … The first edition was a response to a request by many friends and associates for a basic and clear book that provides newcomers with an accessible way to gain knowledge and become productive. The semi major axis of the ellipse is denoted as ‘a’ and semi minor axis is denoted as b. Semi-minor axis (b) − It is the shortest diameter drawn through the center which touches both the perigees (shortest points of an ellipse from the center). Space component In this mode of communication, the satellite stationed at the space receives signals from the earth with the aid of an antenna. Conventionally this is done with the use of a parabolic dish. ➨It covers wide area of the earth hence entire country or region can be covered with just one satellite. This system aids in the data transmitting across the world throughout permanent point on the surface of the earth. Kepler’s 2nd law states that, “For equal intervals of time, the area covered by the satellite is equal with respect to the center of the earth.”. The path followed by a satellite around its primary (the earth) is an ellipse. Signals transmitted from a MEO satellite travel a shorter distance. For real-time communications, the shorter the transmission delay, the better will be the communication system. Power supply: For an elliptical path, it is always desirable that the eccentricity should lie in between 0 and 1, i.e. 0 < e < 1 because if e becomes zero, the path will be no more in elliptical shape rather it will be converted into a circular path. The path followed by a Eccentricity (e) − It is the parameter which defines the difference in the shape of the ellipse rather than that of a circle. Note − Every geo-stationary orbit is a geo-synchronous orbit. The following figure illustrates this concept clearly. and communication infrastructure, promoting adequate capacity building and developing confidence in the use of cyberspace through enhanced online security. But every geo-synchronous orbit is NOT a Geo-stationary orbit. Along with these, there is an important thing which has to be noted. The frequency with which the signal is sent into the space is called Uplink frequency, while the frequency with which it is sent by the transponder is Downlink frequency. Kepler’s 1st law states that, “every planet revolves around the sun in an elliptical orbit, with sun as one of its foci.” As such, a satellite moves in an elliptical path with earth as one of its foci. The course is made of : teaching videos, equipment demonstrations and simulation programs. This tutorial will be suitable for all those readers who wish to learn the fundamental concepts of satellite communication. This article discusses an overview of the satellite communication system. The important kinds of Earth Orbits are −. Figure 1. Communication Satellite can be classified by the orbit used and also by frequency band used. The learner will be able to identify basic terminology associated with any Satellite Objectives: 1. The process begins at an earth station--an installation designed to transmit and receive signals from a satellite in orbit around the earth. Up link frequency is the frequency at which Ground Station is communicating with Satellite The satellite Transponder converts the signal and sends it down to the second earth station. There is a larger propagation delay in satellite communication than in terrestrial communication. Building and launching a telecommunications satellite 3/4 •It takes about 3 years to get a GEO telecom satellite built and launched. It may not be circular. Areas that are not covered usually have low population where it is too expensive to install a base station. They are −. Semi-major axis (a) − It is the longest diameter drawn joining the two foci along the center, which touches both the apogees (farthest points of an ellipse from the center). Basics: Factors in satellite communication Elevation Angle: The angle of the horizontal of the earth surface to the center line of the satellite transmission beam. LEOs will orbit at a distance of 500 to 1000 miles above the earth's surface. In military applications and navigations. The Low Earth Orbit (LEO) satellites are mainly classified into three categories namely, little LEOs, big LEOs, and Mega-LEOs. band used. Johannes Kepler (1571-1630) the astronomical scientist, gave 3 revolutionary laws, regarding the motion of satellites. This orbit can have inclination and eccentricity. The two stations can use a satellite as a relay station for their communication One Earth Station transmits the signals to the satellite. These satellites are considered stationary with respect to earth and hence the name implies. This further reduces the need for sensitive and bulky receiving equipment. Satellite communication has two main components: the ground segment, which consists of fixed or mobile transmission, reception, and ancillary equipment, and the space segment, which primarily is the satellite itself. If it has a 70 cm downlink, you will have to Satellite communications use the very high-frequency range of 1–50 gigahertz (GHz; 1 gigahertz = 1,000,000,000 hertz) to transmit and receive signals. Johannes Kepler (1571-1630) the astronomical scientist, gave 3 revolutionary laws, regarding the motion of satellites. Little LEOs will operate in the 800 MHz (0.8 GHz) range. Medium Earth Orbit (MEO) satellite networks will orbit at distances of about 8000 miles from the earth's surface. Satellite Communications basics. Professionals in the space field will share there vocation for this scientific and technical sector. The initial costs such as segment and launch costs are too high. These satellites are placed at 35,900kms (same as geosynchronous) above the Earth’s Equator and they keep on rotating with respect to earth’s direction (west to east). The following figure shows the difference between Geo-synchronous and Geo-stationary orbits. For research and development sector, in many areas. This tutorial is meant to provide the readers an overview of Satellite Communication and how it works. The satellites in these orbits are Earth Orbit Satellites. Now, let us have a look at the advantages, disadvantages and applications of satellite communications. A satellite is a body that moves around another body in a mathematically predictable path called an Orbit. A communication satellite is nothing but a microwave repeater station in space that is helpful in telecommunications, radio, and television along with internet applications. Ellipse has two foci - F1 and F2, the earth being one of them. Transmission delay can be defined as the time it takes for a signal to travel up to a satellite and back down to a receiving station. The following figure depicts the paths of LEO, MEO, and GEO. Suppose that the satellite covers p1 and p2 distances, in the same time interval, then the areas B1 and B2 covered in both instances respectively, are equal. Introduction to Satellite Communication is designed to meet the needs of working professionals and students. Hence, there are two forces acting on it. The axis of rotation indicates the movement of Earth. Therefore, the eccentricity e of this system can be written as −. A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth.Communications satellites are used for television, telephone, radio, internet, and military applications. The readers should have prior knowledge on the basic concepts of analog and digital communication systems, in order draw benefit from this tutorial. 2.The Earth … Doppler is more noticeableon 70 centimeters than 2 meters; if the satellite you’re trying to work has a70 cm uplink, you will have to adjust your transmit frequency as it passesoverhead. Because of its weaker power it requires a larger antenna, usually above 1.8m (6ft). •Satellites are heavily tested on the ground in facilities that reproduce the space environment: −Mechanical, Thermal, Noise and RF tests As an example, if a GEO satellite requires 0.25 seconds for a round trip, then MEO satellite requires less than 0.1 seconds to complete the same trip. After completing this tutorial, you will be able to learn the significance of satellite communication and its role in present scenario. The second edition There are many Advantages of satellite communications such as −, Distances are easily covered and cost doesn’t matter, Each and every corner of earth is covered, Satellite communication has the following drawbacks −. A communication satellite is a microwave repeater staion in space that is used for tele communcation, radio and television signals. The basic purpose of satellites for mobile communication is to extend the area of coverage. Following are the advantages of Satellite Communication: ➨It is used for mobile and wireless communication applications independent of location. It’s Just likea train whistle that changes pitch as it passes you. Cellular phone systems, such as AMPS and GSM (and their successors) do not cover all parts of a country. (Adapted from SMAD.) These are well described in the following figure. The same geo-synchronous orbit, if it is circular and in the plane of equator, it is called as geo-stationary orbit. ➨It provides wider bandwidth based on SCPC or MCPC allocation types. This shows that smaller, more lightweight receiving terminals can be used at the receiving end. Satellite communication is nothing more than LOS microwave using one (or two) satellites located at great distances from the terminal earth stations, as illustrated in Figure 2 Because of the distance involved, consider the slant range from the earth station to the satellite to be the same as the satellite altitude above the equator. They will guide you through the discovery of satellite communications. Communication with a satellite requires you to focus a narrow Radio Frequency (RF) beam at the satellite. In this communication, electromagnetic waves are used as carrier signals. Satellite Communication Basics The basic elements of a satellite communications system are shown in Figure 1 below. They are used by GPS satellites. If the distance from the center of the object to a point on its elliptical path is considered, then the farthest point of an ellipse from the center is called as apogee and the shortest point of an ellipse from the center is called as perigee. Such orbits which are assigned to satellites, with respect to earth are called as Earth Orbits. In satellite based wireless communication system, the information (data,voice,image,video) is transmitted at microwave frequency using high gain directional parabolic antenna from ground station to the satellite antenna on spacecraft orbiting in the geosynchronous orbit. The chapter provides and explains the basics of advanced communication systems that will allow worldwide access to the Internet by combining Satellite communications, Airborne/Balloon platform, FSO Wireless local area network (LAN), Local Multipoint Distribution System (LMDS), and Terrestrial digital video broadcast. Satellite Link Delays Satellite to the surface of the Earth is 22,300 miles Two way transmission is 44,600 miles C = speed of light = 186,282 miles per second 239 milliseconds Minimum delay Transmit and receive stations on the equator at the same longitude as the satellite. 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