Satellite Communication For Computer Networks

Satellite Communication For Computer Networks A communication satellite is an artificial satellite stationed in space for the purpose of telecommunications. Modern communication satellites use a variety of orbits including geostationary orbits, Molina orbits, other elliptical orbits and low earth orbits. For fixed services, communication satellites provide a microwave radio relay technology complimentary to that of submarine communication cables. They are also used for mobile applications such as communications to ships, vehicles, planes and hand held terminals and for TV and radio broadcasting, for which application of other technologies such as cable is impractical or impossible. HISTORY OF COMMUNICATION SATELLTES The first artificial satellite was the soviet sputnik 1, launched on October 4, 1957, and equipped with an onboard radio transmitter that worked on two frequencies, 20.005 and 40.002 MHz. The first American satellite to relay communication was project score in 1958, which used a tape recorder to store and forward voice messages. After that NASA launched an Echo satellite in 1960. SATELLITE COMMUNICATION FOR COMPUTER NETWORKS. A multi-node, satellite communication system employing a modified broadcast system is disclosed for used with distributed computer networks. The system involves a plurality of network nodes (computer systems) each capable of transmitting to any other node at a single unique frequency, but capable of receiving from all other nodes simultaneously. Each node in the n-node network comprises a single transmitter with up to n-1 receivers, with each node capable of arbitrating a plurality of requests for transmission access. The invention encompasses a method for communicating digital information in a network of geographical distributed computers. GEOSTATIONARY SATELLITES In 1945, Arthur C. Clarke describes a complete communication system that used manned geostationary satellites, including the orbits, solar panels, radio frequencies and launch procedures. But it was failed, because these satellites were impractical due to the impossibility of putting power-hungry, fragile, vacuum tube amplifiers into orbit. The first communication satellite, Telstar was launched in July 1962. Then communication Satellites have become a multibillion dollar business and the only aspect of outer space that has become highly portable. These high-flying satellites are called GEO (Geostationary Earth Orbit) satellites. Geostationary orbit Geostationary satellites space much closer than 2 degrees in the 360-degree equatorial plane, to avoid interference. With a space of 2 degrees, there can only be 360/2 =180 of these satellites in the sky at ones. However, each transponder can use multiple frequencies and polarization to increase the available bandwidth. Modern satellite was weighing up 4000kg and consuming several kilowatts of electric power produced by the solar panels. The effect of solar and planetary gravity tends to move them away from their assigned orbit slots and orientations, an effect countered by on-board rocket motors. This tuning activity is called Station Keeping. ITU has allocated certain frequency bands to satellite users. The main bands are listed as C band was the first to be designated for commercial satellite traffic and the upper case one for uplink traffic. To allow traffic to go both ways at the same time, two channels is required, one going each way. These bands are overcrowded because they ar e also used by the common carriers for terrestrial microwave links. The L and S bands were added by international agreement in 2000. Rain, equipment cost The next highest band available to commercial telecommunication carriers is the Ku band. Bandwidth allocated in the Ka band for commercial traffic, but the equipment needed to use it is still expensive. A modern satellite has around 40 transponders, each with an 80-MHZ band width. The first geostationary satellites had a single beam that illuminated about 1/3 of the earths surface called footprint. A new development in the communication satellite world is the development of low-cost micro stations; it is called Very Small Aperture Terminals (VASATs). In VSATs systems, the micro stations dont have enough power to communicate directly with one another. VSATs have great potential in rural areas. MEDIUM-EARTH ORBIT SATELLITES MEO (Medium-Earth Orbit) satellites tracked as move through the sky. These are lower than GEOs; they have smaller footprint on the ground and require less powerful transmitters to reach them. LOW-EARTH ORBIT LEO (LOW EARTH ORBIT) satellite due to their rapid motion, large numbers of them is needed for a complete system. In this section we will examine, two aimed at voice communication and one aimed at internet service. Iridium An iridium satellite was launched in 1997. Communication service began in November 1998. Iridiums business was providing worldwide telecommunication service using hand-held devices that communicate directly within the iridium satellites. It provides voice, data, paging, and fax and navigation service everywhere on land, sea, and air. These satellites are positioned at an altitude of 750km, in circular polar orbits. Each satellite has a maximum of 48 cells, with a total of 1628 cells over the surface of the earth. Each satellite has a capacity of 3840 channels, or 253440 in all. Global star An iridium alternative design is global star. It based on 48 LEO satellites. But it uses a different switching scheme than that of iridium. Global star uses a traditional bent-pipe design. The call originating at the North Pole is sent back to earth and picked up by the large ground station at Santas Workshop. The call is routed via a terrestrial network to the ground station nearest the cal lee and delivered by a bent-pipe connection. The advantage of global star scheme is that it puts much of the complexity on the ground, where it is easier to manage. Teledesic Teledesic is targeted at bandwidth-hungry internet users all over the world. It was conceived in 1990 by mobile phone pioneer Craig McCaw and Bill Gates. The goal of this system is to provide millions of concurrent Internet users with an uplink of as much as 100Mbps and a downlink of up to 720 Mbps using a small, fixed, VSAT-type antenna, completely bypassing the telephone system. The original design was for a system consists of 288 small-footprint satellites arranged in 12 planes below the lower Van Allen belt at an altitude of 1350km. The design was later changed to 30 satellites with larger footprints. Transmission occurs in the uncrowned and high-bandwidth Ka band. When a user needs bandwidth to send packets is request and assigned dynamically in about 50 msec. LEO EARTH ORBIT HOW SATELLITE COMMUNICATION WORKS? The concept of satellite based network is to transmit and receive signal from ground stations. The purpose of satellite communication is to use it for video transmission and sharing. In simple words a satellite is a device which revolves around the earth either for collecting useful information or for helping transfer of information. HOW DO SATELLITES COMMUNICATE? Satellites communicate through a complex system of telemetry that connects and transmits signals between satellites and earth-bound stations. This system begins with telemetry, tracking and command (TTC) subsystem which tracks and directs signals. TTC produces signal that are directly commensurable to the quantity that is being measured, encoding and transmitting these signal to distant stations on earth. APPLICATIONS OF COMMUNICATION SATELLITES The applications of communication satellites are, Telephone Satellite Television Fixed Service Satellite Direct Broadcast satellites Mobile satellite technologies Satellite radio Amateur radio Satellite internet Military uses Navigation TELEPHONE The first application for communication satellites was in intercontinental long distance telephony. The public switched telephone network relays telephone calls from landline telephones to an earth station where they are transmitted to geostationary satellite. SATELLITE TELEVISION The satellite television is relatively few signals of large band width to many receivers being a more precise match for the capabilities of geosynchronous comsats. Two satellite types are used for North American Television and radio that are Direct Broadcast Satellite (DBS) and Fixed Service Satellite (FSS). FIXED SERVICE SATELLITE It uses the c band and the lower portion of the Ku bands. It is normally used for broadcast feed to and from television networks and local affiliate stations as well as being used for distance learning by schools and universities, business television, video conferencing and general tele- communications. It is also used to distribute national cable channels to cable television head ends. DIRECT BROADCAST SATELLITE It is a communication satellite that transmits to small DBS satellite dishes. It is usually 18 to 24 inches or 45 to 60 cm in a diameter. MOBILE SATELLITE TECHNOLOGIES It was using antenas.

George Washington Carver :: essays research papers fc

  Ã‚  Ã‚  Ã‚  Ã‚  George Washington Carver, most referred to the â€Å"Peanut Man† was born into slavery around 1864 in Diamond, Missouri. His birth date is not known for sure because birth records were not properly kept by the slave owners. As a child, he was very sick and no one ever thought that he would grow to be one of the most distinguished agriculturists in America.   Ã‚  Ã‚  Ã‚  Ã‚  Unfortunately, George never got to know his parents. His father was killed in an accident and his mother was kidnapped by night raiders. So, George was raised by his owners; Moses and Susan Carver. They treated George and his brother Jim as their own sons. As a child, George had exceptional observational skills and a keen curiosity. His love for nature and animals was beyond his age. Moses and Susan tried very hard to satisfy his needs. But, they realized that he needed to go to a regular school. Since colored children were not allowed in the schools for white children, George had to leave the town and go to Neosho, Missouri to attend school. Later he moved to Fort Scott, Kansas to attend High school.   Ã‚  Ã‚  Ã‚  Ã‚  School was full of hardships and struggle for George. Since he never had enough money to pay his fees, he often had to drop out temporarily to earn and then enroll again. During this period he worked many odd jobs as a housekeeper, cook, gardener, and launder. He did every job with devotion and tried to achieve perfection. Thus he gained recognition everywhere he went. After finishing high school, he applied to Highland University and was accepted until the college later learned that he was black and therefore refused his entrance. Finally, at the age of thirty, Carver was finally accepted to Simpson College in Iowa. After a year there, he left to attend the Iowa Agricultural College where he received his Bachelor of Science degree in 1894, and his Masters Degree in 1896. George was the first black American to graduate from this college.   Ã‚  Ã‚  Ã‚  Ã‚  Carver was offered a number of jobs because of his wonderful work ethic, but he accepted the invitation of Booker T. Washington to teach at the Tuskegee Institute, where he accepted a position as an instructor at the Tuskegee Institute of Technology.   Ã‚  Ã‚  Ã‚  Ã‚  At Tuskegee, Carver developed his famous crop rotation method. Nitrate producing legumes like peanuts and sweet potatoes were planted during alternate years. The peanuts and potatoes put nutrients back in the soil that had been taken away when

On A Portrait Of A Deaf Man Essay

Lines one and three also have more beats in them than lines two and four. (If you want to get a bit more technical, one and three are tetrameters, two and four trimeters! Tetrameters have four stresses, trimeters have three stresses). Sound As a reminder of ballad metre, think of the Christmas carol O Little Town of Bethlehem. Using ballad metre means that the poem lends itself to being read aloud and has harmony, rhyme and rhythm that are quite lyrical. Imagery The language used creates extremes of mood. A pattern develops whereby Betjeman uses positive, warm images to evoke happy memories: The kind old face, the egg-shaped head,The tie, discreetly loud,The loosely fitting shooting clothes And then he brutally undermines all this with an image related to death in the following line: A closely fitting shroud. This also happens in stanzas two, four and seven. In these stanzas the death imagery is even worse, bordering on horror: But now his mouth is wide to letThe London clay come in. maggots in his eyes †¦now his finger-bonesStick through his finger-ends Attitudes Although the narrator speaks warmly about his late father he doesn’t use euphemisms. (A euphemism is something said to avoid an unpleasant or offensive word or phrase.) Usually the subject of death is full of euphemisms such as ‘passed on’ or ‘gone to a better place’. Betjeman is more direct about the nature of death, although this can be upsetting. Themes Loss: Betjeman has to come to terms with the loss of his father. Lack of faith: the poet has no faith in God. Death: Betjeman is open and even brutal in the physical descriptions in this poem of the effects of death. Ideas One central idea, hinted at throughout the poem but then clearly revealed at the end, is that death is definitely the end of life. We do not go to heaven or anywhere else because there is no God. â€Å"I only see decay†. There is, however, the more positive proposal that one should cherish the time we have with the people we love, as Betjeman obviously did with his father. Comparison Casehistory: Alison (head injury) * Both poems deal with a before-and-after scenario. The present Alison is in some ways an entirely different character from the pre-accident version. Betjeman views the past and present versions of his father in very different ways. * Readers will perhaps experience sympathy in both poems. One might feel sorry for the post-accident Alison who has suffered brain damage. One might also feel sympathy with Betjeman because he has lost his father. * Both poems deal with death in one way or another: Betjeman’s father has died (as has his faith in God, if it ever existed); Alison is still alive but the Alison of the past is dead. Question How does Betjeman present the character of his father in On a Portrait of a Deaf Man? Answer Betjeman’s father has died and the poet writes this elegy to pay tribute to him. In doing so, he does two distinct things. Firstly, he creates an image of the living father as a warm, nice man. Secondly, he talks of the present state of his father – dead, buried and decaying. The first image is usual in an elegy, the second certainly is not. Betjeman creates a warm, positive image of his father in the opening lines: The kind old face, the egg-shaped head,The tie, discreetly loud,The loosely fitting shooting clothes The first adjective he uses to describe his father is â€Å"kind†, setting a pleasant tone. He then paints a picture of how his father looked and dressed. The following line is the beginning of the technique Betjeman uses to create a different character, his father as he is now, a corpse: A closely fitting shroud. Betjeman contrasts the cold image of death with warm memories of life and as a result, it has much more impact. This technique of juxtaposition continues throughout the poem and as we get to know and like Betjeman’s living father, we’re exposed to more graphic imagery of death: And when he could not hear me speakHe smiled and looked so wiseThat now I do not like to thinkOf maggots in his eyes.

Abnormal Psychology Terms - 9960 Words

Abnormal Psychology Terms 1. even our negative emotions help us survive. for example, arent our suspicious often justified? most likely someone with a ______ theoretical perspective made this statement I knew right after we got home from the hospital that our kid had a problem, the parents said. unless the parent is using 20-20 hindsight, the childs diagnosis most likely is im concerned about Ritalin use; its possible effects on childrens growth, and its increasing heart-attack risk in hypertensive adults an acquaintance worries. your best reply, based on the most recent research is it is obvious that this case of obsessive-compulsive personality disorder arises from an early childhood fixation. which type of psychologist†¦show more content†¦22. 23. a childs distracting behaviors occur only in a school setting, and include failure to follow instructions and finish work, answering questions before they have been completed, and a lot of seat squirming and fidgeting. could ADHD be a diagnosis of this child a client being treated for avoidant personality disorder must increase the number of social contacts per day-- defined as people greeted with at least the phrase, Hello. How are you?-- in order to later engage in some desired activity. most likely, the therapist has which theoretical background a client being treated for schizotypal personality disorder must show up for therapy appointments on time, dress appropriately, and complete some social skills training. most likely the theoretical orientation of the therapist is a client suffers from severe problems in remembering recent information, and has increasing difficulty using ordinary language and other cognitive skills. the resulting diagnosis probably will be a clouding of con sciousness that develops over a short period of time and can often be reversed if its underlying cause can be found is called a friend asks your advice about the best therapy to use for treating borderline personalityShow MoreRelatedPerception Of Abnormal Psychology And Psychopathology774 Words   |  4 Pagesof abnormal psychology and psychopathology and the implicit assumptions of both terms. Considering abnormal psychology is an alternative definition of psychopathology, it is assumed they are different in the eyes of society. Psychopathology is a term focused on the psyche (mind, soul) and a disorder (dysfunction, diseased, unhealthy and illness). It is also based from deviations from statistical and social norms along with maladaptive behavior, distress and impairment. Although abnormal psychologyRead MoreSymptoms And Symptoms Of Abnormal Psychology1527 Words   |  7 PagesAccording to Cherry (2016), abnormal psychology is a branch within psychology that focuses on behaviour that is unusual and not deemed as normal within society. This branch of psychology is composed of a variety of disorders and their causes as well as possible management and/or treatment. With this in mind and within this assignment, I will discuss the causes of abnormal behaviour, discuss the causes and symptoms of mood disorder as well as discuss the background and importance of Sigmund FreudRe ad MoreHow Homeostasis Is Important For Your Life702 Words   |  3 PagesHomeostasis The term I would like to introduce today is Homeostasis. This term is used in psychology and means having balanced body or life. A simpler definition to keep things constant, or in a balanced flow. This could be an organ in the body, your mind, or simply the area of your life. It is important for us to know what homeostasis is because, we all need balance in our lives. Psychology today says â€Å"Homeostasis is critical to survival. If our bodies do not maintain themselves within certainRead MoreHistorical Perspectives of Abnormal Psychology1163 Words   |  5 PagesHistorical Perspectives of Abnormal Psychology Abnormal Psychology PSY 410 January 30, 2012 Historical Perspectives of Abnormal Psychology For many years, various forms of madness have been noted in every culture. Multitudes of theories, as well as some myths, have been developed to explain such conditions. Society’s opinion on what was considered abnormal was based on such phenomenon as paranormal forces, the anger of the gods, the influence of the moon, unstable personality, hereditaryRead MoreThe Effect Of Taking An Abnormal Psychology Class On Students1748 Words   |  7 Pagesnot really have any certain topic within abnormal psychology in mind. I thought the best approach was to start broad and look through articles and see if something stuck out to me as interesting or unique. By doing this method I located two very different articles on PSYCHinfo to examine. The first that I am going to be summarizing and talking about is an article that explained an experiment that was ran to test the effects of taking an abnormal psychology class on students. This experiment basicallyRead MoreSimilarities And Difference s Between Psychodynamic Approaches, Trait, Learning, Biological And Evolutionary, And Humanistic Approaches1279 Words   |  6 Pagesbecomes the abnormal behavior or the eating disorder called Bulimia Nervosa. How there are other abnormal behaviors associated with the disorder as well. The last subject discussed is homosexuality in terms whenever it was taken from the Diagnostic and Statistical Manual of Mental Disorders. Assignment 6.1 The essay defines personality approaches and how they are different but similar as well. Also, an abnormal behavior called Bulimia Nervosa located in a Diagnostic manual terms. HomosexualityRead MorePsychology Is The Study Of Human Behavior1447 Words   |  6 PagesPsychology is the study of human behavior. It is a field that focuses on the human mind, which is a varied landscape of thought and thought processes. When considering the process of studying the field of psychology as a whole there are a great number of avenues to explore the mind. There are different types of psychology, both normal and abnormal as the overarching distinctions. There are also many disorders associated with abnormal behavior psychology such as schizophrenia, anxiety disordersRead MoreChallenges in Identifying Mental Disorders685 Words   |  3 Pagesformatted reflective essay on my research determining, why abnormal behavior or a mental disorder so difficult to understand. When discussing or defining what is abnormal we can run into some challenges on our techniques in defining or diagnosing a patient. There are so many ways a person or client or patient can appear normal or not. Misinterpreting this can lead to very unpleasant results. Definitions of Abnormality The follow defined terms can have great uses or limitations. The statistical typeRead MoreEssay about What Is Abnormal Psychology? What Is Normal Psychology?1141 Words   |  5 Pagesnbsp;nbsp;nbsp;nbsp;nbsp;What is Psychology? In my research of Psychology and its meaning I have come up with many definitions. To sum all of the definitions into one it’s the study ones feelings, thoughts, and their way of thinking and using all of there senses rather its cognitive, physical, or mental. Some other questions that came to mind during my research are what is normal psychology and what is abnormal psychology? nbsp;nbsp;nbsp;nbsp;nbsp;What is normal psychology? Most people consider oneRead MoreCase Study Abnormal Psychology951 Words   |  4 PagesCase Study Name: Institution: Date: Case Study Abnormal behavior relates to the influence of psychological factors, biological factors as well as the social factors referring to inadequate relationships. In the face of diverse definition, abnormal behavior refers to the deviating from norm, which norm is the typical behavior or characteristic of the population. As such, Jim behavior is abnormal because it violates moral and conventional mores of the society (Violates societal standards)