Application Of EM Waves In Satellite Communication Computer Science Essay

Application Of EM Waves In orbiter confabulation computing device Science EssayThis paper deals with the historical development of orbiter chat systems. Then the basic elements of major planet dialogue system on with their features be discussed. Then the working of a planet conversation system and the work of EM swans in this system is discussed and then finally the applications, advantages and limitations of send conference system be discussed.IntroductionElectromagnetic vagabond is a wave of electric car and magnetic matter components which oscillate in descriptor familiar to from each one separate and perpendicular to the sendion of energy coevals. Generally, EM beam of light (the de barrierinationation radiation excludes static electric and magnetic and near fields) is classify by wavelength into radio set, micro-cook, infr ard, the visible starting we perceive as light, ultraviolet, X-rays and gamma rays..The conduct of EM radiation depends on it s wavelength. Higher frequencies chip in shorter wavelengths, and wretcheder frequencies have longer wavelengths. Spectroscopy butt joint detect a frequently wider region of the EM spectrum than the visible vomit up of 400nm to 700nm. Electromagnetic waves as a general phenomenon were predicted by the classical laws of electricity and magnetism, k straightway as Maxwells equations. If you inspect Maxwells equations with pop sources (charges or currents) then you will find that, along with the misfortune of nonhing happening, the theory will similarly admit nontrivial solutions of perpetually-changing electric and magnetic fields.Any electric charge which accelerates, or any changing magnetic field, produces electromagnetic radiation. Electromagnetic instruction about the charge travels at the speed of light. Accurate treatment thus incorporates a concept known as retarded eon. At most wavelengths, however, the information carried by electromagnetic radiation is not direc tly detected by human senses. inseparable sources produce EM radiation across the spectrum,and our technology seat excessively manipulate a broad range of wavelengths.Fig. 1 electromagnetic spectrum artificial disseminate CommunicationA beam is a physical object that orbits or revolves around some celestial body. In general major planet is an slushy satellite locateed in situation for the purposes of conversation, host, surveillance, etc.A satellite dialogue theory (sometimes abbreviated to Comsat) is an artificial satellite stationed in plaza for the purposes of tele communication theory using microwave frequencies. Most communications satellites function geosynchronous orbits or near geo unmoving orbits, although some recent systems riding habit low Earth-orbiting satellites.Communications satellites nominate a technology that is complementary to that of fibre optic torpedo communication melodic phrases. unlike fibre optic communication, satellite communicat ion has a propagation follow to it (also called a path delay) of at least 270 milliseconds, which is the time it takes the radio star sign to travel 35,800 km from creation to a satellite and then tail end to realm. planet Internet connections average a 600-800 millisecond delay, about decade times than that of a terrene Internet affaire. This delay is a altercate to deployment of Virtual private ne devilrks over satellite internet connections.HISTORY OF send discourseThe concept of satellite communications was scratch line proposed by Arthur C. Clarke, foundation on Herman Potoniks pseudonymous work from 1929. In 1945 Clarke published an article richlyborn Extra-terrestrial Relays in the magazine Wire slight World. The article described the fundamentals down the deployment artificial satellites in geostationary orbits for the purpose of relaying radio signal. Thus Arthur C. Clarke is very much quoted as the inventor of the communications satellite. The first artifi cial satellite was the Soviet SPUTNLK-1 launched on October 4, 1957, and aquipped with an onboard transmitter that worked on ii frequencies i.e. 20.005 and 40.002 MHz The first Ameri tin can satellite to relay communications was project SCORE in 1958 which employ tape recorder to store and forward voice messages. Telstar was the first active, direct relay communications satellite belonging to AT T.USE OF EM WAVES IN SATELLITE COMMUNICATIONThe fastest growing and most recent field of communication involves the use of various satellite relays. Let us discuss the place wave communication. In this mode of propagation, electromagnetic waves from the convey advance turn over the receiving aerial either directly or after(prenominal) reflections from priming in the undercoats troposphere region. Troposphere is that portion of the earth which extends up to 16 km from the earth surface. It means in the former, wave reaches directly from the contagion forward pass to receiving ante nna and in later, the wave reaches the receiving antenna after reflection from the reasonableness., where the phase change of 180 degree is also introduced due to reflection at the priming, in the grime reflected wave. Although both the waves leave the transmitting antenna at the same time with the same phase but may reach the receiving antenna either in the phase or out of the phase, because the two wave travel different path lengths. The strength of the resultant waves, thus, at the receiving range may be stronger or weaker than the direct path only when depending upon whether the two waves argon adding or opposing in phase. At receiving stay the signal strength is the vector addition of direct and indirect waves. billet wave propagation is also called as tropospheric propagation because space wave propagates done troposphere. Space wave propagation is of importly in VHF, and racy frequencies because at much(prenominal) frequencies sky wave and ground wave propagation both fail. Beyond 30 MHz sky wave fails as the wavelength becomes too shorts to be reflected from ionosphere and ground waves argon propagating close to the antenna only, as fading is very high. Therefore just after a few(prenominal) hundred feet ground wave also die due to attenuation and wave tilt. Space wave propagation is also called as the line of business of sight propagation because at VHF, UHF and microwave frequencies, this mode of propagation is limited to the line of sight distance and is also limited by the curvature of earth. Although in actual particle space wave propagates redden slightly beyond the line of sight distance due to the diversion in the atmosphere of the earth. In line of sight distance transmitting antenna and receiving antenna can usually see each early(a). In fact, the line of sight distance i.e. range of communication can also be increased by increasing the heights of transmitting and receiving antennas. The curvature of earth and the height o f the transmitting and receiving antennas determines maximum range of communication through direct waves.In fact, the line of sight distance has now been all-embracing by what is known as Space Communication or particularly Satellite communication which has facilitated trans-oceanic propagation of microwaves with the potentiality of large masswidth. By space communication we mean the radio traffic in the midst of a ground station and satellite or space probe, surrounded by satellites or space probes and also between the ground station itself via man made communication satellites or natural space body( e.g. the sun, the moon, the venus etc. ). Earlier it was not possible to propagate beyond the radio horizon and hence it revolutionized the field of communication engineering and it is possible to show that three geosynchronous satellites can establish communication over entire world. Role of electromagnetic waves can be seen by studying the different calls available for satellit e communicationSelection of the hatfulThe selection of the wad is not something that individual emolument bequeathrs decide, but is rather chosen by large satellite operators install on different factors. These are explained belowC-band is still the most widely available worldwide. Ku-band is becoming to a great extent available recently in regions which were less covered in the past (South America, Asia, Africa).C-band is more prone to interference from other transmission service that share the same frequencies (adjacent satellites or terrestrial transmissions) than the higher(prenominal) bands.While the C-band technology is cheaper in itself, it requires larger dishes (1 to 3 m) than Ku- and Ka-band (0.6 to 1.8 m) and therefore imposes relatively higher (installation) costs on the end-user.Ku- and especially Ka-band make better use of satellite capacity.Higher frequency bands (Ku- and especially Ka-) suffer significantly more from signal deterioration ca employ by rainfal l to ensure availability in bad run conditions, the signal has to be much stronger. Note that 0.1% of unavailability means in fact that the service will be disrupt for almost 9 hours over a 1-year period. 1% unavailability founds 90 hours or almost 4 full days. pots of InterestC-band is the oldest allocation and operates in the frequency range around 6 GHz for transmission (uplink) and between 3.7 and 4.2 GHz for reception (downlink).Ku-band is the most plebeian transmission format in Europe for satellite TV and uses around 14 GHz for uplink and between 10.9 and 12.75 GHz for downlink.Ka-band uses around 30 GHz up- and between 18 and 20 GHz downlink frequency.C-band and Ku-band are becoming congested by an increasing summation of users, so satellite service operators are more and more round to the use of Ka-band.Using C-band and K-bandC Band is a name minded(p) to certain portions of the electromagnetic spectrum, as well as a range of wavelengths of light, utilise for commu nications. The IEEE C band and its variations, in particular, are microwave ranges used for certain satellite television broadcasts, and by some Wi-Fi devices, cordless rings, and weather radio detection and rangings. Typical antenna sizes on C-band capable systems ranges from 7.5 to 12 feet (2.5 to 3.5 meters) on consumer satellite dishes, although larger ones alsocan be used. Slight variations of C band frequencies are approved for use in various parts of the world. obtain over IC Band Variants Around The WorldBand convey Frequency(GHz)Receive Frequency(GHz)Extended C Band5.850-6.4253.625-4.200 first-rate Extended CBand5.850-6.7253.400-4.200INSAT C Band6.725-7.0254.500-4.800Palapa C Band6.425-6.7256.425-6.725Russian C Band5.975-6.4753.650-4.150LMI C Band5.725-6.0253.700-4.000K band is defined as a frequency band between 20 and 40 GHz (7.5-15 mm). The IEEE K band is a portion of the electromagnetic spectrum in the microwave range of frequencies ranging between 18 and 27 GHz. K band between 18 and 26.5 GHz is absorbed easily by water vapour (water resonance peak at 22.24 GHz, 1.35 cm).The IEEE K band is conventionally divided into three sub-bands Ka band K-above band, 26.5-40 GHz, mainly used for radar and experimental communications. K-band 18-27 GHz Ku band K-under band, 12-18 GHz, mainly used for satellite communications, terrestrial microwave communications, and radar, especially police traffic-speed detectors.MAIN COMPONENTS OF A SATELLITE COMMUNICATION SYSTEMSatellite communications are comprised of two basic elementsThe satelliteThe ground stationThe SatelliteThe satellite is also known as the space segment. It is composed of the following separate units the satellite and telemetry controls and the transponder.The transponder comprised of the receiving antenna to catch-up signals from the ground station, a broad band learnr, an input multiplexer and a frequency converter that is used to reroute the received signals through a high causalityed ampli fier for downlink.The main function of satellite is to reflect signals. In case of a telecom satellite, the primary role is to pick up signals from a ground station, which is located, a considerable away from the first. This relay action can be two way, as in the case of a long distance phone call. Another use of satellite is the television broadcasts. Number of programs are first up-linked and then down-linked over wide region. The customer having appropriate devices can receive and watch the programs. One of the modern uses of satellite is getting information along with image (commonly known as space/satellite image) of any in demand(p) location on earth.Fig. 2 diagram showing satellite and ground stationThe Ground StationThis is called the earth segment. Earth station is the common name for every installation located on the Earths surface and think for communication (transmission and/or reception) with one or more satellites.A base band processor, an up-converter, high Powered amplifier and a parabolic dish antenna is involved to transmit the terrestrial data to an orbiting satellite. In the case of downlink, the supreme reverse operation is being down and up-linked signals are recaptured through parabolic antenna.WORKING OF A SATELLITESatellite is mainly working on the basis of Electromagnetic waves. In our daily life EM waves are useful for intercommunicate, Internet, T.V etc. For all these electronic equipments are working on the basis of EM waves. Firstly a satellite is keep in the orbit. Then it rotates along the orbit. From the source station it receives signals and spread them to all the electronic equipments. Satellites easily transfer news with in fraction of seconds it means in microseconds. In order send signals the smallest frequency waves are required. At the station the producers send the microwaves to satellite, because microwaves are waves having short frequency when compare to the other waves (Microwaves are electromagnetic waves with frequency from 30MHz to 1GB) ,they can easily penetrate throw the ionosphere, and reaches to satellite. Satellites provide links in two ways. Firstly a satellite provide point to point communication link between one ground station and the other.One ground station transmit signal to the other satellite and next ground station receives them from the satellite. Secondly, satellite receives signals from one ground station and transmits to them to the number of ground pass receivers. It is illustrated in figure 2. Most satellite use frequency bandwidth through from 5.92 to 6.4GHz from transmission of data from earth to the satellite and a frequency bandwidth from 3.7 to 4.1GHz for transmission from satellite to the earth. A satellite can provide service to a certain part of the earth if it is in sight. This can be done only if the satellite remains stationary with respect to the earth.LOW EARTH ORBITING COMMUNICATION SATELLITEIn 1960, the simplest communications satellite ever conceived was launched. It was called Echo, because it consisted only of a large (100 feet in diameter) aluminized charge plate balloon. Radio and TV signals transmitted to the satellite would be reflected back to earth and could be received by any station within chance of the satellite.Fig. 3 diagram showing Echo satelliteUnfortunately, in its low earth orbit, the Echo satellite circled the earth every ninety proceedings. This meant that although just about everybody on earth would eventually see it, no one person, ever saw it for more than 10 minutes or so out of every 90 minute orbit.Telstar satelliteTelstar is the name of various communications satellites including the first ever such satellite able to relay television signals. The first two Telstar satellites were Telstar 1, launched July 10, 1962 and operational until February 21, 1963, and Telstar 2, launched May 7, 1963 and operational until May 16, 1965. They were experimental, and near identical. Telstar 1 relayed the first te levision pictures, telephone calls and fax images through space and provided the first live transatlantic television feed.Telstars orbit was such that it could see Europe and the US simultaneously during one part of its orbit. During another part of its orbit it could see both Japan and the U.S. As a result, it provided real- time communications between the UnitedStates and those two areas for a few minutes out of every hour. Some of the main advantages of low and medium earth orbit include (a) the possibility of using hand-held receiver terminals because satellites are closer to the Earth and can therefore provide stronger signals at the receiver and ground stations need to transmit at lower power (b) the possibility of reusing the frequencies more often than is possible with geostationary orbit because the geographical area covered by low earth orbit satellites is much smaller (c) the possibility of reduction in transmission delay.Fig. 4 diagram showing Telstar satelliteGeostati onary Communications SatellitesIn 1963, the necessary rocket salad booster power was available for the first time and the first geostationary satellite, Syncom 2, was launched by NASA. For those who could see it, the satellite was available 100% of the time, 24 hours a day. The satellite could view approximately 42% of the earth. For those outside of that viewing area, of course, the satellite was NEVER available.Fig. 5 diagram showing Geostationary satelliteINDIAS showtime COMMUNICATION SATELLITE orchard apple treeApple stands for Airline Passenger loading Experiment. It got the name as it was carried as a Passenger by the European space agency. Apple the first Indian three-axis stabilized geo-stationary experimental communication satellite, weighing 673kg was successfully launched on June 19, 1981 from Kourou, French Guyana, by the Ariane Launch vehicle of European Space Agency on its third developmental flight. aft(prenominal) 17 minutes 25 seconds the craft was successfully placed in the transfer orbit. The space craft sub-systems were functioning normally. Test commands have been issued from SHAR to the APPLE space craft successfully.Fig. 6 diagram showing APPLE satelliteLaunch Date 19.06.1981Launch Vehicle Ariane-1(V-3)Type of Satellite Geo-Stationary SatelliteMission Experimental geostationary communicationWeight 670 kgCommunication VHF and C-bandStabilization Three axis stabilized (biased momentum) with Momentum Wheels, Torques Hydrazine found Reaction control systemMission life Two old ageAPPLICATIONS OF SATELLITE COMMUNICATIONThe breakthrough provided by satellites in telecommunications resulted in a major research and development effort in all the associate technologies. Most of the early work concentrated on international point to point telecommunications applications. Later, the application of satellite communication was extended to the direct satellite broadcasts (1970s), mobile communications (1980s), and personal communications (1990s). In general, satellites are table service the mobile and broadcast.Radio and Television BroadcastingSatellites have been used since 1960 to transmit broadcast television signals between the profits hubs of television companies and their meshing members. Sometime, a whole set of programs is transmitted at once and recorded at the affiliate, and then broadcast to the local populace according to the appropriate time. In the 1970s it became possible for private individuals to download the same signals that the network and cable companies were transmitting, using C-band reception dishes. This free viewing of the corporate contents by individuals let to scrambling and subsequent resale of the descrambling codes to individual customers, which started the direct-to-home industry. The direct-to-home industry has gathered even greater response since the introduction of digital direct broadcast service..Business Radio And TVDigital television has made it possible to distribute information w ithin organizations and companies that are geographically dispersed, or to deliver distance education. Similarly, digital radio allows for the delivery of radio function to relatively small unkindly user groups.Thin Route or Trunk Telephony telecom operators have been using satellite communications for many years to carry long-distance telephone communications, especially intercontinental, to complement or to bypass submarine cables. To the end-user this is transparent the phone calls are routed automatically via the available capacity at any given moment.Mobile satellite telephoneMobile telephony allows the user to make telephone calls and to transmit and receive data from wherever he/she is located. Digital cellular mobile telephony such as GSM has become a worldwide standard for mobile communications, but its services lack coverage over areas that are sparsely populated or uninhabited (mountains, jungle, sea), because it is not economically viable or practical for the network operators to build antennas there. Satellite telephony seems to be able to provide a possible solution to the paradox of providing voice and data communications services to these other locationsMarine CommunicationsIn the marine community, satellite communication systems such as Immarsat provide good communication links to ships at sea. These links use a VSAT type device to connect to geosynchronous satellites, which in turn links the ship to a land establish point having respective telecommunications system.Global Positioning ServicesAnother VSAT orientated service, in which a small apparatus containing the ability to determine navigational coordinates by calculating a triangulating or the signals from multiple geosynchronous. legions Satellite SystemFor military communications Army, Air force and Navy use both frozen(p) and mobile satellite systems. In addition to the normal communications, military communications are also required for tactical communications from remote and in hospitable locations.The special requirements of military communication terminals are high reliability, ruggedness, compact, operations under hostile environment, immunity to jamming, ease of portability and transportation, etc. Examples of military satellite communications systems areDSCS (US AF)SKYNET (UK)NATO (NATO)FLTSATCOM (US NAVY)MILSTARBecause of the special frequency band used in Military satellite system and other special requirements, Military satellite Systems are always much costlier and it takes longer time to design and develop compared to commercial satellite communications systems. Realizing that not all communications are strategic in nature, there is a trend now to use commercial communications system as far as possible. US Department of Defence is one of the major users of commercial atomic number 77 satellite system with their own gateway.wideband Satellite SystemBroadband satellite service is an emerging service which has caught the fancy of many for merging the demand of worldwide fibre like access to telecommunications services such as computer networking, broadband Internet access, interactive multimedia and high quality voice. These systems use advanced satellite technology at Ka band or Ku band frequencies to achieve the high bandwidth requirements.Examples of proposed Broadband Satellite systems are Teledesic, SkyBridge, SpacewayLIMITATIONS OF SATELLITE COMMUNICATIONLatency (Propagation Delay)Due to the high altitudes of satellite orbits, the time required for a transmission to navigate a satellite link (2/10ths of a second from earth station to earth station) could cause a variety of problems on a high speed terrestrial network that is waiting for the packets.Poor BandwidthDue to radio spectrum limitations, there is a fixed amount of bandwidth allocable to satellite transmission.NoiseThe strength of a radio signals strength is in proportion to the square of the distance travelled. Due to the distance between ground station and sa tellite, the signal ultimately gets very weak. This problem can be solved by modulation of carrier wave. destructionThe outer space has always fascinated people on the earth and communication through space evolved as an offshoot of ideas for space travel. The early idea of using artificial satellites for communications is found in a science fiction Brick Moon by Edward Evert Hale, published in 1869-70. While the early fictional accounts of satellite and space communications splay little resemblance to the technology as it exists today, they are of significance since they represent the origins of the idea from which the technology eventually evolved. The satellite communication through the EM waves has many applications for the smooth functioning of life and it made the communication with each other very simple. In the area of satellite communications, the technology has been responsive to the imaginative dreams. Hence it is also expected that technological innovations will resul t the evolution of satellite communications towards the visions of today.AcknowledgmentI would like to speak my gratitude to all those who gave me the possibility to complete this term paper. I want to convey department of Electronics and communication of lovely professional university for giving me permission to become this term paper. I have further more to thank the EMFT capacity member, Mr. Princejeet Singh. I am bound to the physics faculty for their stimulating support.My friends Amit and Sulabh back up me in this term paper. I want to thank them for their help, support, interest and important hints.Especially I would like to thank my sister who helped me and enabled me to complete this term paper.