Satellite Communication Systems Computer Science Essay

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The satellite systems and communication field budgets are an important tool for designing radio frequency links, because of the significance, it must have the attention of the engineers who are involved in design and operate the radio frequency links. Learning about link budget is important, the modern approaches of designing has turned towards the use of computers to do all the calculations which are required for the design, in order to save time and effort and to achieve the accuracy in calculations that all means good accuracy leads to good design. SatMaster is a package developed by Arrowe Technical Services used to find out satellite link budget and all the parameters that are related to satellite radio links. Three experiments will be designed to help the students learn about the link budget by using SatMaster Pro Package software.

The use of satellites in communication systems is widely used, most television coverage is travelled by satellite, even reaching directly from space to the home, the bulk of telephone and data communication also travels by satellite. Communication satellite permits two or more points on the ground (earth station) to send messages to one another stations over great distance using radio waves. Technology is always advancing, and satellite and terrestrial communication will improve in quality, capability and economy (Bruce R. Elbert, 2008, p11). Satellite communications began in October 1957 with the launch by the USSR a small satellite called Sputnik 1 (4.10.1957) (Jules E. Kadish & Thomas W. R. East, 2000, p25). Satellites have many applications and are very important in voice communications, video & radio transmission, navigation (GPS), remote sensing (maps, weather satellites) etc. The importance of satellite capacity to cover a very wide geographical area, which is not a specific distance of the satellite systems as well as non-specific factors, is therefore natural that provided a service similar to the various regions, regardless of the form of the region (Walter L. Morgan, Gray D. Gordon, 2009, p234). It has some benefits, such as, Cost Effectiveness, Global Availability, Superior Reliability, Superior Performance, Rapid link capacity for all users on the surface of the ground and Immediacy, these features make satellite communication systems unique in design. The disadvantages of the satellite show in the Launching satellites into orbit are costly, Satellite bandwidth is gradually being used up and there is a larger propagation delay in satellite communication than in terrestrial communication. As well as its many uses, Communications & broadcasting, Military & reconnaissance, Weather and Research. Satellite systems use frequencies between 1 to 50GHZ, and operate in the microwave (B. G Evans, 1999, p292).

Satellite communication systems

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A satellite consists of communications and broadcasting radio and television from the two main units, Unit of service and communication. The first unit contains parts of the work of governing the serving satellite telemetry and satellite supply of electrical energy necessary for its work. The communication unit containing the transponder, the devices send and receive signals to and from the ground. Analogue technology was being used as the carrier for each channel in digital technology may be sent up to ten different channels on the same carrier and carrying can be a vibration or frequency (Gary D. Gordon and Walter L. Morgan, 1993, p108). The satellite cannot send all the information to Earth, but covers a certain area of land. This region into a circular, the area of this region depends on the strength of the satellite. It is important to know information about the areas of satellite coverage and strength appropriate with Diameter is inversely proportional to the dishes for the reception of the transmission of such satellites (International Telecommunication union, 2002, p75). "The more force to send the satellite dish was too weak to receive the satellite signal a large scale, where the signal strength of the satellite dish was too large to receive the signal is small" (Gary D. Gordon and Walter L. Morgan, 1993, p322). Satellite communications system is composed of two segments which is satellite (space segment) and earth station which is the second part of a satellite system, each segment has certain characteristics. Satellite is composed of three separate units the fuel system, the satellite and telemetry control and the transponder. The ground station will be known as tracking, telemetry, Command and Monitoring (TTC&M) station (Gary D. Gordon and Walter L. Morgan, 1993, p322). The ground segment consists of all the earth stations, which send and receive signal to the satellite or from satellite to earth station. TTC&M ground stations are not included in the ground segment. The ground segment terminals consist of three basic types: fixed terminals, transportable terminals and mobile terminals (Timothy Pratt, Charles W. Bostian& Jeremy E. Allnutt, 2003, p221). There are three forms of connectivity, point-to-point, point- to-multipoint and multipoint-to-point (Jules E. Kadish & Thomas W. R. East, 2000, p151). Each of this connectivity can be present through one satellite and two or more earth stations. Most communication satellites are in geosynchronous orbits (geostationary) to be above the surface of the earth about 35,900 km (Timothy Pratt, Charles W. Bostian & Jeremy E. Allnutt, 2003, p221). It can be related to a ground station with the satellite communications provided, that the satellite above the earth rotating speeds of rotation of the Earth itself, and shows the result of it being stable for the land, and is located in some of the stations all the time. If no satellite communications in the synchronous orbit, it will pass over a given ground station for a short period during each orbit. It could cover the broadcast of satellite communications, which is orbiting the satellite at speeds equal to the speed of rotation of the Earth, about one third of the Earth's surface. "Therefore, three or more communications satellites, a properly placed around the globe, it can be send signals covering the world" (Gary D. Gordon and Walter L. Morgan, 1993, p322).

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Most of satellites synchronous with earth rotation and they take 24 hours for the revolution. Before discussing satellite orbits in more general terms, it is important to understand the natural laws that control the movement of satellites. The shape of the orbit is limited to circular and elliptical. These are based on Kepler's Laws and state that:

the orbital plane of any Earth satellite must divide the Earth centrally.

the Earth must be at the centre of any orbit (Timothy Pratt, Charles W. Bostian & Jeremy E. Allnutt, 2003, p221).

There are four categories for satellite orbits:

LEO: low earth orbit satellite, geocentric orbits ranging in altitude from (0-2,000) km. providing mainly mobile data services, includes military intelligence satellites, weather satellites (Louis J. Ippolito, Jr, 2008), (Andrew F. Inglis & Arch C. Luther, 1993, p270).

MEO: medium earth orbit satellites, Geocentric orbits ranging in altitude from 2,000 km to just below geosynchronous orbit at 35,786 km. Providing mobile telephony services. Includes navigation satellites (GPS, Galileo, Glonass) (Louis J. Ippolito, Jr, 2008), (Andrew F. Inglis & Arch C. Luther., 1993, p270).

GEO: geostationary earth orbit satellites, has a circular orbit and is classified as equatorial, its orbital period is one sidereal day (23h, 56 min, 4.091 s). The orbit around Earth exactly matching Earth's sidereal rotation period. Major existing telecommunications and broadcasting satellites fall into this category. There are two types: (GEO) that are stationary with respect to a fixed point on the earth and (NGEO) that are moving with respect to a point on the earth. Includes commercial and military communications satellites (Louis J. Ippolito, Jr, 2008), (Andrew F. Inglis & Arch C. Luther., 1993, p270).

HEO: High Earth Orbit, Geocentric orbits above the altitude of geosynchronous orbit 35,786 km (Louis J. Ippolito, Jr, 2008, p140), (Andrew F. Inglis & Arch C. Luther, 1997, p270).

The ITU was formed in 1932 from the International Telegraph Union. It has three primary functions allocations and use of the radio frequency spectrum, telecommunications standardization and development and expansion of worldwide telecommunications (International Telecommunication union, 2002, p45). The ITU divides the globe into three telecommunications service regions:

Region 1: Europe and Africa.

Region 2: south and North America and Greenland.

Region 3: the Pacific Rim countries.

Each service region is treated as independent in terms of frequency allocations, because the general assumption is that systems operating in any one of the regions are protected by geographic separation from systems in the other service regions (G. Maral and M. Bousquet, 1993, p304).

ITU allocated a frequency band for various services provided by the satellite. Some of These services are:

Fixed Satellite Services (FSS): radio communication service between earth stations at specified fixed points when one or more satellite are used, in some cases includes satellite-to-satellite links, which may also be affected in inter satellite service, for connection between one or more earth stations at specified fixed points and satellite used for service other than fixed satellite service (e.g. mobile satellite service, broadcasting-satellite service).

Mobile Satellite Services (MSS): radio communication service between mobile earth stations and one or more space stations or between space stations used by this service, between mobile earth stations by means of one or more space station, if system so requires for connection between these space stations and one or more earth stations at specified fixed points.

Broadcasting Satellite Services (BSS): radio communication service in which signals transmitted or retransmitted by space stations intended for direct reception by the general public using very small receiving antennas(TVROs).(G. Maral and M. Bousquet, 1993, p304).

There are 3 major components in a satellite, they are:

Transponder and antenna system: The transponder is a high frequency radio receiver, a frequency down converter and a power amplifier, which is used to transmit the downlink signal.

Power Package: It is a power supply to the satellite. The satellite must be powered either from a battery or a solar energy system.

Control and information system & rocket thruster system: The control and information system and the rocket thruster system are called the station keeping system. (Gary D. Gordon and Walter L. Morgan, 1993, p322).

The satellite link is composed primarily of three segments:

the transmitting Earth station and the uplink media.

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inter-satellite link between the satellites.

the downlink media and the receiving Earth station (Bruce R. Elbert, 2008, p186).

A satellite earth station is a communications facility with a microwave radio transmitting and receiving antenna and required receiving and transmitting equipment for communicating with satellites the earth station itself is usually an antenna that includes a low-noise amplifier, a down-converter, as well as an electronics receiver. The ground station of the functions to send a signal in the case of uplink from bass band signals Pass through the base band processor and then through the up converter and through parabolic dish antenna up to an orbiting satellite. and In the case of downlink Earth station working to reverse the signals received during the parabolic antenna to base band signal(Louis J. Ippolito, Jr., 2008, p180)(International Telecommunication union, 2002, p45). The ground stations to send information through satellite and there are three multiple access techniques: If the different transmissions are differentiated only for the frequency band, it is considered as Frequency Division Multiple Access (FDMA). Whereas, if transmissions are distinguishes on the basis of time, it is considered as Time Division Multiple Access (TDMA). Finally, if a different code is adopted to separate simultaneous transmissions, it is considered as Code Division Multiple Access (CDMA), as shown below (Timothy Pratt, Charles W. Bostian& Jeremy E. Allnutt, 2003):

Time Division Multiple Access (TDMA): one technology for shared medium (usually radio) networks. It allows several users to share the same frequency by dividing it into different time slots the channel capacity issue by dividing a single radio channel into timeslots and then allocating a timeslot to a user (Timothy Pratt, Charles W. Bostian & Jeremy E. Allnutt, 2003, p221).

Code division multiple access (CDMA): is any use of any form of spread spectrum by multiple transmitters to send to the same receiver on the same frequency channel at the same time without harmful interference (Timothy Pratt, Charles W. Bostian & Jeremy E. Allnutt, 2003, p221).

Frequency Division Multiple access (FDMA): is the oldest and most important of the three main ways for multiple radio transmitters to share the radio spectrum. The other two methods are Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA). Gives users an individual allocation of one or several frequency bands, allowing them to utilize the allocated radio spectrum without interfering with each other. Most duplex FDMA systems must transmit and receive simultaneously (Timothy Pratt, Charles W. Bostian & Jeremy E. Allnutt, 2003, p221).

Satmaster ProMk6.5 package

Link budgets are the standard tool for designing and assessing the radio frequency (RF) and other physical layer aspects of fixed and mobile satellite systems, and must be understood by many engineers and managers with design and operation responsibilities. In the past, link budgets were very personalized as to style and content, however, they remain the primary format for presenting results of such analyses. More recently, commercial software tools have appeared on the market to structure and automate the process of creating link budgets, although some are extremely costly and are only practical for corporate users (Arrowe, 2010).Other similar tools are provided for free, but must be employed to design links for a particular satellite system as directed by the operator (Arrowe, 2010).

The main objective of using this program is to calculate the link budget of radio communication links, Developed by Arrowe Technical services. This software package is used by radio engineers who are involved in the design of satellite radio links. It is a general purpose tool for the satellite industry (Arrowe, 2010).

SatMaster is a highly-recognized yet low-cost PC-based software tool offered through the web by Arrowe Technical Services of the UK. Engineer or student who studies in the field of satellite communications must learn and understand myself in the application and use of SatMaster for a range of satellite communications applications (Arrowe, 2010).

Problem description

In order to achieve high performance of the characteristics and advantages links, satellite link functions must operate in an integrated and coordinated manner. Several challenging problems associated with integrated satellite link design are:

How to model and coordinate the satellite characteristics link processes, specifically in the area.

Good problem statement would be the link between the theoretical and practical application, the students must understand from the experience properties of the radio link design. The test showing how propagation, outage, rain attenuation, ect. Phenomena affect on the microwave link performance and how radio link engineering rules can be implemented (Lehpamer, H., 2004, p69). As well as the understanding of the properties and applications, and foundations, which parameter depends on it? How do you imagine the form and style of thinking and experience, this is up to the question of how to improve the idea of experience? What is the foundation upon each experiment?

How to analyze the performance to understand the radio link design so that optimization experiment technique can be employed to improve the understanding of students, and the program SatMaster itself, and how will the way of designing at least 3 experiences enable the student who works in this field to understand the properties of radio link design and to cover the most important features of this package.

What are the characteristics and advantages of the experiment that will be designed in order to enable the student to understand and realize the goal of this experiment and what is its purpose?

How to select suitable parameters for each goal, and what are the important elements that highlight the experience in the design?

By the design of any experiment, must take into account that the purpose of experiments is the student's education, then what scientific methods to design the experiment? What are the requirements for achievement?

How to create experiments, including a full understanding of the issues related to radio link. These problems are most representative in the satellite link design in research and applications.

Aim & Objective

Performing the experiments gives the student the experience and previous studies have showed that this has a positive impact on the student's performance. Any user can become better in using the SatMaster package by practicing the experiments in the lab.

There are two main goals for any experiment, the first goal is to make students familiar with the package and give them the confidence to deal with the program, and the second goal is to give them the chance to identify and recognize some of the important parameters of a satellite radio link which are considered as essential in designing links. This will save time by showing students the important guidelines which will help them to start designing any link. Good understanding by the student and the engineer who are working in this field will benefit by using these experiments and improve their performance.

The main aim of this research is designing three experiments to cover the most important features of this package, use SatMaster pro package to help students to understand and learn the radio link design by designing lab experiments, these experiments depend upon the features available by this package to design radio link budget.

Characterizing link budget performance of a digital communication system is a key step for comparison of different architectures and techniques. The design of any telecommunication link makes use of the communication equation which contains all of the basic elements and design parameters in the communication system. Each element in the power budget equation plays a fundamental role in the system design.

Related work

Complete review in the proposed application SatMaster. And the Program SatMaster (for engineers and also for students who are studying engineering) is an essential step to proficiency of design and operation of satellite systems. And review of the built-in features of SatMaster Pro.

Thorough reading and understanding in radio link design and link budget, And important points relating to Radio Link Design.

A standard academic lab sheets could benefit from it, since it is necessary to produce three distinct lab experiments. The form and order of the experiments will be designed later.

Project Resources

Supervisor.

University library and internet.

SatMaster application documentation.

University lab.

Proposed Solution

The final form of each experiment will be specified after completing the design of the radio links. The design will consider different cases for each radio link design in order to show the effects of link parameters on the performance of the system. It highlights the main parameters of satellite radio links and the relationship between them. These experiments introduce a better knowledge for students and help them to understand the satellite link design. To help the students be familiar with the package and guide them to the essential parameters of link budget design, and make them able to deal with the package with confidence.

Experiments include the training of SatMaster pro package, at the same time it offers a view of the necessary parameters that the package deals with during the use of the software to make the required calculations and experiments. It also identifies the essential parameters that a satellite link is affected by.

The link between education and work in the laboratory makes the student is understand the things in theory by application of the laboratory, therefore is very important for the learning of the student. The project goal will design three experiments to cover the most important features of this package, using the SatMaster pro package to help the student to understand and learn the radio link design by designing lab experiments, these experiments depend on the features available by this package to design Radio Link budget. And show tests on how propagation phenomena affect microwave link performance and how radio link engineering rules can be implemented.

Research Plan

According to these requirements the project working steps will be as follows:

The link designer is generally interested in determining system design or link performance requirements of the system based on overall performance criteria for the end-to-end performance of the system. The inclusion of propagation effects usually enters into the analysis in link budget portion of the system design.

Detailed study for satellite communication and radio link design, concepts and important points to be studied are:

The main components of communication satellite systems: the satellite, Earth station, transponders, high power amplifiers (HPA), etc.

Satellite orbits, geostationary satellites and Atmospheric effects (Troposphere and Ionosphere).

Antenna designing and noise effects, Modulation systems schemes and Radio link budget, Calculation of Uplink path loss, Calculation of Transmit antenna gain, Calculation of Transmit EIRP, Calculation of uplink to noise ratio, Calculation of receiver antenna gain, Calculation of link margin.

Equivalent Isotropically Radiated Power (EIRP), Gain to noise Temperature (G/T), Saturation Flux Density (SFD), Propagation Models, Carrier to noise ratio (C/N), and Carrier to noise temperature ratio.

Rain effects, rainfall regions, ITU rain models which contain (ITU (DAH), Crane Global, and Crane 2-component), Error correction and Satellite frequency bands (Louis J. Ippolito, 2005, p86-89). The DAH Rain model can calculate Phi (Latitude (deg)), Hs (Earth Station Elevation (km)), Theta (Elevation Angle (deg)), Re (Effective Earth Radius (km) (default =8500 km)), Freq (Frequency (GHz)), Zone (Rain Climate Region), the zone is used to calculate the rain rate exceeded for 0.01% of the average year (Louis J. Ippolito, 2005, p86-89).

4. Learn the tools and features of the package, that would be completed by the inspection of each term in the program and understand its function and get the theoretical calculations without the use of the package. After that Applying practical examples by using the package to obtain the results finally, comparing the results with those obtained by theoretical calculations.

5. As a proposed action, a suggested demo of students can be picked and try the produced experiments, collecting their ideas and thoughts about how much they can learn from each experiment and the average curve of learning. Change some parameters in place for access to different results and different study situations carefully. Compared with some of the theory and practice and explain the reasons for each case.

6. Design the experiments that are related with starting from the basic fundamentals, which are essential and ending with core of the communication systems and satellite radio links. Introduce a better knowledge for students and help them to understand the satellite link design. Account all the factors involved to the transmission signal from the satellite to the ground station in figure 1.

Figure (1) Propagation Impairments over Earth between the satellite and the earth station

Source: Louis (2008, 140)

Evaluation plan

An experiment is a way of investigating fundamental relationships between variables. The experiment can be used to assist solve practical problems and to support or reverse theoretical assumptions. Basically the evaluation is a critical way of looking at the results and conclusion and deciding how accurate and how reliable the results are, and how to consider improving the experiments and proposing new experiments. Two major tasks can be focused on, the first one is to explore the task which asks the student to research the information needed for the design, in order to give them the chance to recognize the information resources and help them to understand what they are trying to achieve. The second is to exercise the task which will ask them to apply and execute the program and to get the results. Make use of imagination to invent a much better experiment. Better monitoring and control of variables could also lead to an increase in the reliability of conclusions.

The benefits of designing experiments

By learning, skills obtained will make the user a top performer.

Will get the knowledge one needs to use and solve problems.

Will learn new ways of obtaining results

The user will have satisfaction in the work they do and have more confidence.

Summary

It is good project for students and Engineers who are working in this field, satellite and communication engineering. However this report and all its contents are to be considered as a primary, and as I started searching with this massive field, it will be finished in the final report. There are several packages that are used to experiment satellites like design still have to find which package has the future that could help the student to observe and investigate the results (SatMaster pro & SatMaster+).

The link between education and work in the laboratory means the student is expected to understand things in theory by Application within the laboratory, therefore studying as a student is very important. The project goal is designing three experiments to cover the most important features of this package, use SatMaster package to help students to understand and learn the radio link design by designing lab experiments, these experiments Depend on the features available by this package to design Radio Link budget. And show how propagation phenomena affect microwave link performance and how radio link engineering rules can be implemented.

The package has full up/down link budget calculators and up link power requirements, it is able to find HPA (high power amplifier) size and bandwidth and power usage per carrier, also it is able to calculate the atmospheric losses and rain fade margin for any required availability for up and down links by implementing ITU rain models (2010, Arrowe).

Good problem statement would be the link between the theoretical and practical application, the students must understand from the experience properties of the radio link design. Analyzing the performance is important to understand the radio link design so that optimization experiment technique can be employed to improve the understanding of students, and the program SatMaster itself, and how will the way of designing at least 3 experiences enable the student who works in this field to understand the properties of radio link design and to cover the most important features of this package.

Conclusion

The objective of this project is to study and understand the important parts of modern technology which is satellite communications. It shows the academic methods for a student or an engineer who is working with the satellite links and for those who have difficulty in understanding or getting hands-on the radio satellite links. These experiments will be designed in the final report to cover the main features of the package how these features will be implemented in a useful way.

SatMaster was developed by ARROWE technical services and it is available in the University laboratory for the experiments to be carried out. This project is for engineers and technical professionals who are in the fields of designing radio link. Moreover, it can also be used by students who are continuing their studies in the design of satellites. The reader must also be familiar with ITU regulations. The ITU regulations consider link budget calculations which are an essential step in the design of a radio communications system. The link budget calculation enables the losses and gains to be seen, and devising a link budget enables the distribution of losses, gains and power levels to be made if changes need to be made to enable the radio link design to meet its operational requirements.

This program is considered one of the best programs to study the characteristic of the link for the students or engineers who are working in this field, and to understand the features of radio link design by applying them in the Satmaster program, which will enable the student or the engineer to understand how to apply the knowledge.

Reference

Jules E. Kadish & Thomas W. R. East, (2000). Satellite communication fundamentals. Artech House. p25, p151

Walter L. Morgan & Gray D. Gordon, (2009). Communication Satellite Handbook. John Wiley & Sons. p234

B. G Evans.(1999). Satellite Communication Systems. (3rd ed.). The institution of Electrical Engineers. P292

Timothy Pratt, Charles W. Bostian & Jeremy E. Allnutt. (2003). Satellite communication. (2nd ed). John Wiley & Sons. p221

Bruce R. Elbert. (2008). Introduction to satellite communication. Artech House. , p11, p186

Louis J. Ippolito, Jr. (2008). Satellite Communications Systems Engineering. Atmospheric Effects, Satellite Link Design and System Performance. A John Wiley and Sons.p140

International Telecommunication union. (2002). Handbook on satellite communications (3rd ed.). A John Wiley and Sons. P75, p45

G. Maral & M. Bousquet. (2002). Satellite communications systems (3rd ed.). A John Wiley and Sons. P304

Gary D. Gordon & Walter L. Morgan. (1993). Principles of communication satellites (4th ed.). Wiley. P108, p322

Andrew F. Inglis & Arch C. Luther (1997). Satellite technology an introduction (2nd ed.). Focal Press. P270

Lehpamer, H. (2004). Microwave transmission networks: Planning, design, and deployment. McGraw-Hill professional engineering. New York: McGraw-Hill. P189

Louis J. Ippolito (2005), Propagation Effects Handbook for Satellite Systems Design (5th ed.). pg 86-89

J. Bogucki, J. Jarkowski, and E. Wielowieyska (2008), Propagation on modern satellite paths, in Proc. Nineteenth Int. Wrocław Symp. Ex- hib., Electromagn. Compat., Wrocław, Poland. pp. 374-377.

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Table of Contents

Abstract......................................................................................................................... (I)

Introduction................................................................................................................... (1)

Satellite communication systems.................................................................................. (1)

Satmaster ProMk6.5 package........................................................................................ (6)

Problem description....................................................................................................... (7)

Aim & Objective............................................................................................................ (8)

Related work.................................................................................................................. (9)

Project Resources........................................................................................................... (9)

Proposed Solution.......................................................................................................... (9)

Research Plan................................................................................................................. (10)

Evaluation plan.............................................................................................................. (12)

The benefits of designing experiments.......................................................................... (12)

Summary........................................................................................................................ (13)

Conclusion..................................................................................................................... (14)