The Volkswagen Beetle :: essays research papers

The peoples car &8211 generically, Volkswagen in German &8211 is almost as old as the automobile, and the type was familiar in Germany long in front the advent of the Volkswagen. commonly these popular cars were minimal cars, though size and simplicity did not necessarily bring them within the reach of the ordinary man in the street.Henry Ford did create a successful universal car, to sell at a low price, and his Model T with its 2.9-litre engine was by no means a small car, nor was the Model A that followed it. When it was in production in the late 1920s, small proper cars in Germany ranged from the 700-cc DKW to the 1-litre Opel, with small Adlers, the BMW Dixi (a license-built Austin Seven) and the NSU-Fiats to come. These stimulated desire rather than a years wage for an average worker. This prompted motorcycle manufacturer Zundapp to commission a low-cost car design from Dr. Ferdinand Porsches new design studio. The project did not get far, but a Porsche-designed NSU that r eached that prototype stage in 1933 accurately foreshadowed the Volkswagen.The idea of a peoples car appealed to Porsche, and it fascinated Adolf Hitler. When the Nazi Party came to power in 1933, adept of his pet notions was the concept of motoring for the masses, and a meeting with Porsche was to be a meeting of minds. Once again Porsche was commissioned to design a popular car, and when the start ludicrously tight financial limits were relaxed he accepted the technical challenge.It is possible that Porsche received too much credit for the design of the Volkswagen, for most of the technical elements had been seen before in the work of such men as Ledwinka, Rumpler, Rabe and Nibel. The Volkswagen reflected the Porsche Buros earlier designs, but it was to reach production and eventually succeed beyond the wildest limits of the Thirties dream.In 1931, the Porsche separatist front suspension was patented. It interested many manufactures, and was to be important to the Volkswagen. I t was devised around torsion bars, not new as such, but in this arrangement the devil transverse bars were housed in tubular cross members, with a lower trailing link at each end, and an upper link pivoted to the frame and feature with a friction shock absorber. This was lighter than the then-common transverse leaf spring arrangement, but it meant that the wheels rolled with the body.

Youth Athletics Essay -- Sports Violence Parents Essays

Youth Athletics In Reading, Massachusetts, one parent was trounce to death by another parent after a scuffle at a young person hockey mealy (Sachs). In Palin Beach, Florida, a puzzle of a little league player was sentenced to three years in prison after taking a gun and pointing it at a prepare (Gehring). In Port St. Lucie, Florida, a headline in the evening paper read, Spectator Bites off Mans Ear at Youth Baseball Game (Pallerino). why would parents act in such negative ways? They are too competitive at youth athletic events. During my five years refereeing youth sports, I have seen many examples of negative behavior. This past September, a parent, whom I have known for a few years, approached me after a basketball game her childs team had lost. I knew something was going to happen, but there was nothing I could do. Mind you, this is a 7th grade tournament, so the children were 11-and-12 year-olds. The mother asked me loudly, Why did you severalize my daughter to shut up? I r eplied that I only told her daughter to hush because her daughter told me quite hatefully that she wasnt the only person that fouled. Now, granted at the time this child was losing the game, I knew that she wasnt feeling too good about herself, so I had told her calmly that she didnt need to be irreverent. However, as I attempt to explain this to the mother, she told me that I do not have the right to do such a thing. She neglected to understand that referees frequently levy technical fouls for disrespectful behavior on the court, but I had just given a warning. I never imagined such a response when the game was over. This mother unsaved me with every vulgarity imaginable. She also told me that I was the loser of the community and that I could never do anythin... ...search.epnet.com. 2 Nov. 2003.Cox, RachelS. (2001, Mar. 23). Abstract. CO Researcher. 11.11. Oct. 29,2003. <http//library.cqpress.com/cqresearchersGehring, John. More Schools Calling Foul on Unsportsmanlike Behavio r. Education Week 21.7 (17 Oct. 2001) 6. EBSCOhost faculty member Search Premier. Camden-Carroll Lib. http//search.epnet.com/direct. 31 Oct. 2003.Hypes, Julia. Personal Interview. 23 Nov. 2003.Pallerino, Michael J. Is the Rash of Parental Violence at Youth Sporting EventsIncreasing, or Are We Just Now Recognizing it as a Problem? SportingKid Magazine. National Alliance for Youth Sports. 2001. http//www.navs.org. 28 Nov. 2003.Sachs, Michael L. Lighten Up Parents USA Today 129.2666 (Nov. 2000) 62-63. EBSCOhost Academic Search Premier. Camden-Carroll Lib. Morehead State University. http//search.epnet.com . 31 Oct. 2003.

Seven Solitudes of Lorsa Lopez and The Spirits Essay -- Comparative, S

The assumed motive of men has been an issue of gender politics throughout S raze Solitudes of Lorsa Lopez by Sony Labou Tansi and The House of the Spirits by Isabel Allende. The African and Latin American cultures have become societies vulnerable to traditional biases of women being the weaker race, liable for blame of mens problems. Through their attitudes, physical strengths and abusive behaviors physically, verbally and emotionally, men continue to oppress the women of their societies. Male power has been institutionalized by society, while women continuously combat their socially-accepted roles by using the only weapons to their disposal their voices and sexuality.Estina Benta and Clara try to conform to their own standards of liveliness by attempting to defy their male spouses. Using the power to voice their opinions and withhold inexpugnable self-confidence, both are able to control the emotions of their male authorities. (Provide context for this quote) Clara walked around like a silentshadow. She didnt even look at him. She walked honorable past him as if he were a piece of furniture. They hadnt resumed sleeping in the same bed (Allende 113). Abstaining from communication and sex, Clara is able to expose Estebans vulnerability and form her own power and independence.This particular vulnerability that is revealed through Esteban Trueba is the very essence of his eventual dispiritedfall. He felt defeated for the first time in his life (104) (put citation at the end of the sentence) which led to his abusive, possessive behavior towards Clara. He wanted far more than her body he wanted control everywhere that undefined and luminous material that lay within her (96). The necessity of obsessive control over women is the backbone o... ...m as he needed to be loved, even if it meant he had to resort to extreme measures. But he realized that Clara did not belong to him and thatshe probably never would (96).Taking charge using his physical advantage Esteb an pulled her from the bed, dragged her down the hall, pushed her down the stairs, and thrust her into the library (132). Words such as pulled, dragged, pushed and thrust correlate to sexual violence, which is a mans only dominating accept that can keep him in a position of power. However being a strong individual does not mean having physical strength, rather it marrow strong-minded, emotionally stable and the power to speak out all weapons of the women of African and Latin American cultures. Through their words and actions such as sex strikes, their power is illuminated and true equality is found because women are also men (23).

Jack London Essay -- essays research papers

Jack capital of the United Kingdom was a prolific writer, one of the most widely withdraw American writers of the early 20th century. During his short life, he wrote fifty books, plus many articles and short stories. Besides being one of the most widely order authors, he was also the highest-paid. However, Jack London did not spend all of his time writing. Besides being an author, he also was a gold prospector, a homeless, a pirate, a sailor, and a factory worker. London was determined to live an adventurous lifeI would kind of be ashes than dust I would rather that my spark should burn out in a brilliant blaze than it should be stifled by dryrot. I would rather be a brainy meteor, every atom of me in magnificent glow, than a sleepy and permanent planet. The proper function of man is to live, not to exist. I shall not waste my old age in trying to prolong them. I shall use my time. (Parks and Recreation)This attitude fueled Jack London&8217s daring life. But his brash spirit las tly lead to his demise. London lived a short life, dying at age 40. He was known to be strikingly handsome and was a celebrity. His passionate publications were famous for his ideas on the struggle of survival and the questions of death. London&8217s novels were usually based on nature and adventure, coming from real life experiences, which appealed to millions of readers. Jack London was born on January 12, 1876 in San Francisco, California. The relationship between his mother, Flora ...

Potential Abuse of Human Cloning :: Argumentative Persuasive Topics

Potential Abuse of Cloning   It is understood that using forms of genic manipulations has great potential, if the usage is based on the idea that it will be used to improve agricultural production, medicine technology, and the like.  To use cloning as a coping device for those who mourn loved ones, or simply cannot deal with natures life and death process, however, is simply wrong.  It is not only idealistically wrong, but ethically, morally, and even de jure unjust.  If cloning human beings becomes a reality, it will be the process that will slowly deteriorate the diversity of the world, and the ability for people to deal with negative occurrences in their life.   Ethically and politically cloning seems to be breaking all the rules, already.  Supporters of cloning ar pushing for a reform of any law or built-in right, banning cloning, to be changed.  Cloning is currently backing an ethical uproar around religious communities, due to its new explosio n of advancements. Contemplations of a new race, and its laws, be already in the making.Despite the hoards of people who are anxiously gathering to ban it, scientists are continuing to push forward with experimentations.Some of them believe that no matter if a person, or group, likes cloning or not, they better learn to deal with it because it will not be stopped.It is hard to say whether or not the growing populations who are against cloning will be able to do anything to prevent it as a whole, or even partially.Regardless of how the U.S. chooses to deal with this issue, each country has their own plans and opinions.There are many variations on the new cloning policies, and the outcome of this new technology will be very interesting to see.           There are three unalike types of cloning.The first two are somatic manipulation and germline genetic manipulation.Somatic manipulation only changes the somatic gene makeup of a single person (their c orporal appearance).Germline genetic manipulation, however, passes all manipulated genes through and throughout the future generations (so any odd physical appearance or disease that is eliminated in one child will be forever eliminated in its heritage line) (Hayes pars. 10-11).       Many doctors are now suggesting parents test their unborn children and cure them of any maladies they could possibly encounter during their entire life through somatic manipulation (mostly including major outwardly physical disabilities).This way they can do everything possible to perfect their childs outward appearance and mental abilities prior to birth.

Potential Abuse of Human Cloning :: Argumentative Persuasive Topics

Potential Abuse of Cloning   It is understood that using forms of genetic manipulations has great potential, if the usage is based on the idea that it go away be utilize to improve agricultural production, medicine technology, and the like.  To use cloning as a coping device for those who mourn loved ones, or simply cannot deal with natures demeanor and death process, however, is simply wrong.  It is not but idealistically wrong, but ethically, morally, and even lawfully unjust.  If cloning human beings becomes a reality, it will be the process that will tardily deteriorate the diversity of the world, and the ability for people to deal with negative occurrences in their life.   Ethically and politically cloning seems to be breaking all the rules, already.  Supporters of cloning argon pushing for a reform of any law or constitutional right, banning cloning, to be changed.  Cloning is currently backing an ethical uproar near religious communities, du e to its new explosion of advancements. Contemplations of a new race, and its laws, atomic number 18 already in the making.Despite the hoards of people who are anxiously gathering to ban it, scientists are continuing to push forward with experimentations.Some of them believe that no matter if a person, or group, likes cloning or not, they better learn to deal with it because it will not be stopped.It is hard to say whether or not the growing populations who are against cloning will be able to do anything to prevent it as a whole, or even partially.Regardless of how the U.S. chooses to deal with this issue, each country has their own plans and opinions.There are many variations on the new cloning policies, and the outcome of this new technology will be very interesting to see.           There are three different types of cloning.The first two are somatic manipulation and germline genetic manipulation.Somatic manipulation only changes the somatic gene makeup of a single person (their physical mien).Germline genetic manipulation, however, passes all manipulated genes throughout the future generations (so any odd physical appearance or disease that is eliminated in one child will be forever eliminated in its heritage line) (Hayes pars. 10-11).       Many doctors are now suggesting parents test their unborn children and cure them of any maladies they could possibly encounter during their entire life through somatic manipulation (mostly including major outwardly physical disabilities).This way they can do everything possible to perfect their childs outward appearance and mental abilities prior to birth.

Critique of a Toy Essay

The toy I have chosen is the LEGO 750 BRICKS BOX TOYThis toy is good for children of ages 2 to 6 years, it allows for free constitute and helps children to be creative, it helps come apart their learning skills and is good for their hand to eye co-ordination which also which also increase their physical and intellectual development ( Ellis flood 2010 Child culture for students in Ireland Dublin Gill & Macmillan ) Marg bet Macmillan approach to the curriculum was designed around toy which develops a childs fine and gross motor skills and manual dexterity and she regarded free exploit as an important aspect of a childs development (Josephine Donohue & Frances Gaynor 2011 Education & Care in the Early age 4th edition Dublin Gill & Macmillan). Its also a learning toy that teaches the children numbers by counting the bricks and creates the things they see around them, they come in different sizes, shapes and colours which gets the children thinking on what to build with it, which c ould be a house, car, farms etc.COST AVAILABILTYThey are available in the following stores and costArgos 19.99Smiths 32.99 represent master 39.99Tesco 39.99Toy city 24.99Supersavers 29.99SAFETY OF TOYThe toy is safe for the children as there are no small parts that can be swallowed or put in the nose or ears as they are block sizes which are relatively handy. They can be washed in smarmy water since they are plastics and can also be sanitised with disinfectant.PLAY VALUE OF TOYMy Lego Bricks allows the children to explore the environment by constructing their own house, cars, farms, trucks etc. My Lego bricks helps developlanguage skills through verbal communication with the Lego man by pretends sour, talking to their toys or moving them from one house to other. My Lego bricks help the children to build and extend their knowledge, pinch and skills in a way that makes sense to them My Lego bricks allow the children to develop their own ideas in the construction world. My Lego bri cks foster the development of their social skills by interacting with one another as they build their houses or cars. It also helps the childrens physical development as they put so many hours into the play.DURABILITY OF TOYThe Lego bricks is durable because its make out of plastic rubbers. The plastics are very strong so they can withstand a lot of impact, rough handling, throwing, kicking and still not break. The Lego bricks are very durable as its thick coating of plastic rubbers makes it strong and its washable which is important for hygiene reason especially in a pre trail where we have lots of children from different homes.STORAGE OF TOYThe Lego bricks comes in a box, which makes it easy for storage which can be placed on the shelve or under the table or bed.VALUE OF TOY IN RELATION TO THE CHILDS OVERALL DEVELOPMENTPHYSICAL DEVELOPMENTThe physical development of the childrens is enhanced as their gross motor skills and fine motor skills improves. It also helps their eye to ha nd co-ordination as they require a higher denseness level in the construction or bringing of their imagination to life of what they see themselves creating.INTELLECTUAL DEVELOPMENTPlaying with the Lego bricks, a child can be introduced to maths through abacus numbers, letters on blocks/bricks also height, weight, matching, sorting and their vocabulary skills can be essential. Creativity play can also be developed as Lego bricks allow a child to be imaginative with theirvarious construction and pretend play too can be played with the animals and Lego man. Their hassle solving skills is developed too as they would want to make sure the outcome of their constructed blocks is perfect and their concentration skills is improved because they are engrossed by their play as they put in a lot of hours to achieve their goals.LANGUAGE DEVELOPMENTThis is a form of communication which is either written, spoken, signed language or body language. The child is able to communicate with an adult or to pretend play with the Lego man, as the adult talks to the children in a group performing with the Lego helps improve their understanding of languages. Playing with the Lego bricks help the child develop their language skills by naming the structured he/she have constructed and interaction between the children is encourage as they were able to share with one another and communicate as they build their house, car, living rooms, kitchens, farms, gardens, place, letters, animals will teach children vocabulary and help them make a constructive sentences. They help the child count numbers, letters and the images on the Lego is clearly stated for the child to pronounced with the help of an adult if he/she needs it. ruttish DEVELOPMENTPlaying with the Lego bricks help the children develop their emotional development as the children will be anxious to build their house, car, trucks, farms and also help the childs growth, ability to feel and express an increasing range of emotions. Play with the Lego bricks can be rewarding and promote a sense of achievement for the child as the out come of what they have built will boost their ego and self esteem and can also help to release aggression as all their energy is put into it.SOCIAL DEVELOPMENTSocial development can be defined as the ability to interact effectively with others or developing a sense of right or wrong (their morals development) Ellis Flood 2010 Child Development Gill MacmillanA group of children can play with lego bricks which helps them interact withone another and the children also get to interact with an adult which will help their social development.RECOMMENDATIONS FOR CHANGES/IMPROVEMENT TO THE ITEMSI would advocate that the cost be reduced and quality improved so as to make it affordable and more durable by getting the value for your money. I would also recommend that the bricks/blocks be moulded in numbers/alphabets and the colours more brighter.

Internet and Intranet Connectivity Through Wireless Local Area Network (Wlan)

CHAPTER 1 Introduction Chapter 1 Introduction 1. 1 What is Wlocal argona network? 1. 1. 1 Wlocal area network piano tuner Local receiveledge base Ne dickensrk (WLAN) is a kind of local bea network which established employ a piano tuner link surrounded by the service providers and the clients using galore(postnominal) piano tuner equipment. This network development is found on the IEEE 802. 11 measure. 1. 1. 2 IEEE 802. 11 IEEE 802. 11 denotes a set of Wireless LAN/WLAN standards au thereforetic by on the job(p) group 11 of the IEEE LAN/MAN Standards Committee (IEEE 802). The term 802. 11x is too apply to denote this set of standards and is not to be anomalous for any one(a) of its elements. There is no single 802. 1x standard. The term IEEE 802. 11 is besides apply to refer to the original 802. 11, which is now neartimes c on the wholeed 802. 11 bequest 1. The 802. 11 family circulating(prenominal)ly entangles six e truly carry-the- publicize modulation techniq ues that all use the same protocol. The near popular techniques ar those defined by the b, a, and g amendments to the original standard security was originally included and was later enhanced via the 802. 11i amendment. 802. 11n is former(a) modulation technique that has recently been developed the standard is still under development, although products designed ground on draft versions of the standard atomic number 18 being sold.Other standards in the family (cf, h, and j) be service enhancements and extensions or corrections to previous specifications. 802. 11b was the first widely au consequentlytic radio networking standard, fol offseted by 802. 11a and 802. 11g 1. 802. 11b and 802. 11g standards use the 2. 40 gigahertz (gigahertz) mountain, operating (in the United States) under Part 15 of the FCC Rules and Regulations. Be sire of this choice of relative relative frequence stack, 802. 11b and 802. 11g equipment so-and-so incur hindrance from micro twine ovens, c ordless telephones, Bluetooth thingummys, and other appliances using this same band. The 802. 1a standard uses the 5 gigacycle band, and is therefore not affected by products operating on the 2. 4 GHz band. Table 1. 1 Protocol Summary of IEEE 802. 11 Protocol Legacy 802. 11a 802. 11b 802. 11g 802. 11n Release Date 1997 1999 1999 2003 2006 Operating absolute absolute frequency GHz 2. 4-2. 5 5 2. 4-2. 5 2. 4-2. 5 2. 4 and/or 5 Th boulderedput (Typ) Mbps 0. 7 23 4 19 74 Data Rate (Max) Mbps 2 54 11 54 248 = 22 ant Range (Indoor) meters 25 30 35 35 70 Range (Outdoor) meters 75 100 110 cxv 160 2 1. 2 Why it should be utilise? Bangladesh entered the Internet world in 1993 using off railway E-mail services.Online Dial-up services started in 1996 through VSAT based information connectivity. accurately it is not possible to pull up stakes a Dial-up conjunctive to all be work it uses the BTTBs telephone line. While Dial-up is active the phone line is crabby and it is not possible t o pass water a client frequently than 4/5 Kbps speed. Using an ADSL modem it poop be cast upd to more than 2 Mbps. But it is not enough for a corporate user and also it is very costly and there argon many other problems which has described below. The Ethernet connectivity stinker give a upper limit of 100 Mbps. But its vomit is too low-spirited. Wireless LAN has vast benefits over wired network in both(prenominal) aspects.In our country especially in big cities like Dhaka, it is very hard job to establish a wired network all over the city. Because, it is over populated, grammatical constructions were made with taboo any proper plan and also the roads. Generally the wire lines are established over head, which is not so secured. Wire seat be broken imputable to any kind of natural or man made problem. It whitethorn be theft. Or it can be utilise by any one by taking a parallel line from it. It may create leak of entropy security. It is also very big-ticket(prenominal) to establish a copper wire network road by road and maintenance of it.Besides that there are many rivers, cannels in our county, and also hill tracks in some parts. It is not possible to give a wired network over those. For all those reasons it is not a wise stopping come in to use a wired network in our country. A Wireless LAN can be more reliable, low cost, convenient network studying in a spiriteder place aspects. There are a matter of Internet Service Provider (ISP) companies in our country giving Wireless LAN support to the clients. Those are cognize as Wireless ISP. These ISPs give internet or intranet service to the clients as their requirements. Those networks are reliable and also secured.It is easy to establish a connection in the companys reporting area using a wireless device at the client end. The Wireless ISP Company should fetch proper resources to give that insurance reporting. A model of a Wireless ISP companys wireless part for Bangladesh is given below. T he nation wide link can be a optical fiber or microwave link. Here the main coverage is shown in Dhaka city and thus BSSs are shown at here is more than one. It can be expand the network in other areas by adding additional equipments required to establish a BSS. And also it can give coverage on other areas by establish same network on that area. compute 1. 1 Model of a Wireless ISP 1. 3 Why one should be interested in WLAN field? The telecom in circulatery is ever-changing with breathtaking speed. There are a lot of tele discourse and Wireless ISP companies working in our country and there are a lot of companies to father. At present telecommunication is the nigh challenging and interesting field out of all other engineering fields. All the telecom company has some common construction. So, there are many similarities in the midst of a mobile or PSTN (Public Switched Telephone Network) operator and a Wireless ISP.The skills one gather from a Wireless ISP can use in the telecom c ompanies. The man can be skilled on instalment unlike devices, surveying a site, proposing a link budget. He can face the practical problems occur in installing piano tuner networks and can be skilled in solving those problems and also troubleshoot the devices and the radio link. In the mobile operators, there are many restrictions. wiz can not work with all things. But as still Wireless ISP companies are smaller in our country one can get fortune to work in different arms which go out increase his know gots and skills.Lastly it can be say that, as it is a challenging field, the person likes facing challenges give enjoy working in this field 4 1. 4 Organization of this report This Internship report has seven chapters in total. The second chapter contains theory some the radio frequency properties and different modulation techniques In third chapter, different RF forward passs and it accessories are described. Fourth chapter contains the Wireless LANs theory and architectu re in brief. Chapter five analyzes to survey a site, and how to budget a link. The sixth chapter describes the device installation process for the APERTO and CANOPY devices.The seventh and final chapter is the concluding chapter where limitations of this works are reported and few suggestions of our work are provided along with the concluding remarks. 1. 5 Aims and objectives 5 RF Properties and intonation Techniques CHAPTER 2 6 Chapter 2 RF Properties and Modulation Techniques 2. 1 Radio Frequency 2. 2. 1 Radio Frequency Radio frequencies are lofty frequency alternating legitimate (AC) blesss that are passed along a copper conductor and then radiated into the air via an transmitting aerial. An antenna qualifys/transforms a wired indication to a wireless bes poster and vice versa.When the high up frequency AC repoint is radiated into the air, it forms radio waves. These radio waves propagate (move) away from the source (the antenna) in a straight line in all acquireions a t once. 2. 2. 2 RF Behaviors RF is sometimes referred to as smoke and mirrors because RF seems to act erratically and inconsistently under given circumstances. Things as small as a connexion not being tight enough or a s lilting electric resistance mismatch on the line can cause erratic demeanour and undesirable issues. The following sections describe these types of behaviors and what can happen to radio waves as they are distributeted.Gain Gain, illustrated in symbol 2. 1, is the term utilize to describe an increase in an RF auspicate premium 2. Gain is usually an active process meaning that an external s bureau source, much(prenominal) as an RF amplifier, is utilise to amplify the call attention or a high- come along antenna is utilize to focus the beam width of a signal to increase its signal amplitude. visualise 2. 1 Power gain However, passive processes can also cause gain. For workout, reflected RF signals combine with the main signal to increase the main sign al strength. Increasing the RF s signal strength may require a positive or a negative result.Typically, more top executive is s better, but there are cases, much(prenominal) as when a transmitter is radiating power very close to legal power output limit, where added power would be a serious problem. 7 Loss Loss describes a strike in signal strength ( mental image 2. 2). Many things can cause RF signal loss, both(prenominal) while the signal is still in the cable as a high frequency AC electrical signal and when the signal is propagated as radio waves through the air by the antenna. Resistance of cables and connectors causes loss due to the converting of the AC signal to heat.Impedance mismatches in the cables and connectors can cause power to be reflected back toward the source, which can cause signal degradation. Objects directly in the propagated wave transmission path can absorb, reflect, or s destroy RF signals. Loss can be intentionally injected into a circuit with an RF attenuator. RF attenuators are accurate resistors that convert high frequency AC to heat in order to reduce signal amplitude at that point in the circuit. 2 conformation 2. 2 Power loss Being able to measure and compensate for loss in an RF connection or circuit is all important(p) because radios have a receive sensitivity threshold.A sensitivity threshold defined as the point at which a radio can clearly distinguish a signal from background noise. Since a receivers sensitivity is finite, the transmitting station essential transmit signal with enough amplitude to be recognizable at the receiver. If losses occur between the transmitter and receiver, the problem must be corrected all by removing the objects causing loss or by increasing the transmission power. Reflection Reflection, (as illustrated in get wind 2. 3) occurs when a propagating electromagnetic wave impinges upon an object that has very large dimensions when compared to the wavelength of the propagating wave 3.Refle ctions occur from the surface of the earth, buildings, walls, and many other obstacles. If the surface is smooth, the reflected signal may remain intact, though there is some loss due to absorption and scattering of the signal. Figure 2. 3 Reflection 8 RF signal reflection can cause serious problems for wireless LANs. This reflecting main signal from many objects in the area of the transmission is referred to as multipath. Multipath can have severe adverse affects on a wireless LAN, such(prenominal)(prenominal) as contaminating or canceling the main signal and causing oles or gaps in the RF coverage area. Surfaces such as lakes, metal roofs, metal blinds, metal doors, and others can cause severe reflection, and hence, multipath. Reflection of this magnitude is never desirable and typically requires special functionality (antenna diversity) within the wireless LAN hardware to compensate for it. Refraction Refraction describes the fold of a radio wave as it passes through a medium o f different density. As an RF wave passes into a denser medium (like a crime syndicate of cold air lying in a valley) the wave allow be bent such that its direction changes.When passing through such a medium, some of the wave forget be reflected away from the intended signal path, and some depart be bent through the medium in another direction, as illustrated in Figure 2. 4. 3 Figure 2. 4 Refraction Refraction can start out a problem for long outgo RF links. As atmospheric conditions change, the RF waves may change direction, diverting the signal away from the intended Diffraction Diffraction occurs when the radio path between the transmitter and receiver is obstructed by a surface that has sharp irregularities or an otherwise rough surface 3.At high frequencies, diffraction, like reflection, depends on the geometry of the obstructing object and the amplitude, contour, and polarization of the incident wave at the point of diffraction. Diffraction is comm exclusively confuse w ith and improperly used interchangeably with refraction. Care should be taken not to confuse these terms. Diffraction describes a wave deflection somewhat an obstacle (Figure 2. 5), whereas refraction describes a wave bending through a medium. Taking the rock in the pond example from above, now consider a small twig sticking up through the surface of the water near where the rock.As the ripples hit the stick, they would be blocked to a small degree, but to a larger degree, the ripples would bend around the twig. This illustration shows how diffraction acts with obstacles in its path, depending on the makeup of the obstacle. If Object was large or erose enough, the wave qualification not bend, but rather might be blocked. 9 Figure 2. 5 Diffraction Diffraction is the slowing of the wave strawman at the point where the wave front strikes an obstacle, while the rest of the wave front maintains the same speed of propagation. Diffraction is the effect of waves turning, or bending, arou nd the obstacle.As another example, consider a machine blowing a steady stream of smoke. The smoke would flow straight until an obstacle entered its path. Introducing a large wooden block into the smoke stream would cause the smoke to curl up around the corners of the block causing a noticeable degradation in the smoke velocity at that point and a remarkable s change in direction. Scattering Scattering occurs when the medium through which the wave travels consists of objects with dimensions that are small compared to the wavelength of the signal, and the upshot of obstacles per unit volume is large 3.Scattered waves are produced by rough surfaces, small objects, or by other irregularities in the signal path, as can be seen in Figure 2. 6. Figure 2. 6 Scattering more or less outdoor examples of objects that can cause scattering in a mobile communications form include foliage, street signs, and lampposts. Scattering can take place in two primary ways. First, scattering can occur when a wave strikes an uneven surface and is reflected in many directions simultaneously. Scattering of this type yields many small amplitude reflections and destroys the main RF signal.Dissipation of an RF signal may occur when an RF wave is reflected off sand, rocks, or other jagged surfaces. When scattered in this manner, RF signal degradation can be significant to the point of intermittently disrupting communications or causing complete signal loss. 10 Second, scattering can occur as a signal wave travels through particles in the medium such as heavy dust content. In this case, rather than being reflected off an uneven surface, the RF waves are individually reflected on a very small scale off small particles.Voltage Standing Wave Ratio (VSWR) VSWR occurs when there is mismatched impedance (resistance to current flow, measured in Ohms) between devices in an RF system. VSWR is caused by an RF signal reflected at a point of impedance mismatch in the signal path. VSWR causes return loss which is defined as the loss of forward zip fastener through a system due to some of the power being reflected back towards the transmitter. If the impedances of the ends of a connection do not match, then the maximum number of the transmitted power allow for not be received at the antenna.When part of the RF signal is reflected back toward the transmitter, the signal level on the line varies instead of being steady. This variance is an indicator of VSWR. 2 As an illustration of VSWR, imagine water flowing through two garden hoses. As long as the two hoses are the same diameter, water flows through them seamlessly. If the hose connected to the faucet were significantly larger than the next hose down the line, there would be backpressure on the faucet and even at the connection between the two hoses. This standing backpressure illustrates VSWR, as can be seen in Figure 2. . In this example, you can see that backpressure can have negative effects and not nearly as much water is transferred to the second hose as there would have been with matching hoses screwed in concert properly. Figure 2. 7 VSWR-like water through a hose VSWR Measurements VSWR is a ratio, so it is expressed as a relationship between two numbers. A typical VSWR value would be 1. 51. The two numbers relate the ratio of impedance mismatch against a perfect impedance match. The second number is always 1, representing the perfect match, where as the first number varies.The lower the first number (closer to 1), the better impedance matching your system has. For example, a VSWR of 1. 11 is better than 1. 41. A VSWR measurement of 11 would denote a perfect impedance match and no potentiality standing wave would be present in the signal path. Effects of VSWR Excessive VSWR can cause serious problems in an RF circuit. Most of the time, the result is a marked decrease in the amplitude of the transmitted RF signal. However, 11 since some transmitters are not protected against power being utilis e (or returned) to the transmitter output circuit, the reflected power can burn ut the electronics of the transmitter. VSWR effects are evident when transmitter circuits burn out, power s output levels are unstable, and the power observed is significantly different from the expected power. The methods of changing VSWR in a circuit include proper use of proper equipment. Tight connections between cables and connectors, use of impedance matched hardware throughout, and use of high-quality equipment with calibration reports where necessary are all good preventative measures against VSWR.VSWR can be measured with high-accuracy instrumentation such as SWR meters, but this measurement is beyond the scope of this text and the job tasks of a network administrator. 2. 2 Spread Spectrum 2. 2. 1 Spread Spectrum Spread spectrum is a communications technique characterized by wide bandwidth and low peak power. Spread spectrum communication uses various modulation techniques in wireless LANs and p ossesses many advantages over its precursor, define band communication 4. Spread spectrum signals are noise-like, hard to detect, and even harder to intercept or demodulate without the proper equipment.Jamming and interference have a lesser affect on a permeate spectrum communication than on limit band communications. For these reasons, spread spectrum has long been a favorite of the military. 2. 2. 2 Narrow great deal Transmission A concentrateband transmission is a communications technology that uses alone enough of the frequency spectrum to carry the data signal and no more, spread spectrum is in opposition to that mission since it uses much wider frequency bands than is necessary to transmit the information. This brings us to the first requirement for a signal to be considered spread spectrum.A signal is a spread spectrum signal when the bandwidth is much wider than what is required to send the information. 4 Figure 2. 8 illustrates the difference between narrowband and sp read spectrum transmissions. One of the characteristics of narrow band is high peak power. More power is required to send a transmission when using a smaller frequency range. In order for narrow band signals to be received, they must stand out above the general level of noise, called the noise floor, by a significant tot. Because its band is so narrow, and high peak power ensures error-free reception of a narrow band signal. 12Figure 2. 8 Narrow band verses Spread Spectrum on a frequency expanse A compelling argument against narrowband transmission-other than the high peak power required to send it-is that narrow band signals can be jammed or experience interference very easily. Jamming is the intentional overpowering of a transmission using unwanted signals transmitted on the same band. Because its band is so narrow, other narrow band signals, including noise, can completely eliminate the information by overpowering a narrowband transmission much like a passing take away overpow ers a quiet conversation. 2. 2. 3 Spread Spectrum TechnologySpread spectrum technology allows taking the same amount of information than previously using a narrow band carrier signal and spreading it out over a much larger frequency range. For example, 1 megahertz at 10 Watts with narrow band, but 20 MHz at 100 mW with spread spectrum. By using a wider frequency spectrum, we reduce the probability that the data allow be corrupted or jammed. A narrow band jamming attempt on a spread spectrum signal would likely be thwarted by virtue of only if a small part of the information falling into the narrow band signal frequency range. s s Most of the digital data would be received error-free 4.Today spread spectrum RF radios can retransmit any small amount of data loss due to narrowband interference. While the spread spectrum band is relatively wide, the peak power of the signal is quite low. This is the second requirement for a signal to be considered spread spectrum. For a signal to be considered spread spectrum, it must use low power. These two characteristics of spread spectrum (use of a wide band of frequencies and very low power) make it look to most receivers as if it were a noise signal. Noise is a wide band, low power signal, but the difference is that noise is unwanted.Furthermore, since most radio receivers will view the spread spectrum signal as noise, these receivers will not attempt to demodulate or interpret it, creating a slightly more secure communication. 2. 2. 4 Frequency Hopping Spread Spectrum (FHSS) Frequency hopping spread spectrum is a spread spectrum technique that uses frequency agility to spread the data over more than 83 MHz. Frequency agility refers to the radios ability to change transmission frequency abruptly within the operational RF frequency band 4. In the case of frequency hopping wireless LANs, the usable portion of the 2. GHz ISM band is 83. 5 MHz, per FCC regulation and the IEEE 802. 11 standard. 13 How FHSS Works In frequency hopping systems, the carrier changes frequency, or hops, according to a pseudorandom date. The pseudorandom eon is a list of several frequencies to which the carrier will hop at qualify time intervals in the lead repeating the figure of speech. The transmitter uses this hop sequence to select its transmission frequencies. The carrier will remain at a certain frequency for a specified time (known as the dwell time), and then use a small amount of time to hop to the next frequency (hop time).When the list of frequencies has been exhausted, the transmitter will repeat the sequence. Figure 2. 9 shows a frequency hopping system using a hop sequence of five frequencies over 5 MHz band. In this example, the sequence is 1. 2. 449 GHz 2. 2. 452 GHz 3. 2. 448 GHz 4. 2. 450 GHz 5. 2. 451 GHz Figure 2. 9 Single frequency hopping system Once the radio has transmitted the information on the 2. 451 GHz carrier, the radio will repeat the hop sequence, starting again at 2. 449 GHz. The process of repeating the sequence will continue until the information is received completely.The receiver radio is synchronized to the transmitting radio hop sequence in order to s receive on the proper frequency at the proper time. The signal is then demodulated and used by the receiving computing device. Effects of Narrow Band Interference Frequency hopping is a method of sending data where the transmission and receiving systems hop along a repeatable pattern of frequencies together. As is the case with all spread spectrum technologies, frequency hopping systems are resistant-but not immune-to narrow band interference. In example in Figure 2. 9, if a signal were to interfere with our frequency hopping signal on, say, 2. 51 GHz, only that portion of the spread spectrum signal would be woolly-headed. The rest of the spread spectrum signal would remain intact, and the lost data would be retransmitted. 14 In reality, an interfering narrow band signal may occupy several megahertz of bandwi dth. Since a frequency hopping band is over 83 MHz wide, even this interfering signal will cause little degradation of the spread spectrum signal. Frequency Hopping Systems The IEEE and outside standards regarding FHSS systems describe 1. The frequency bands which may be used 2. Hop sequences 3. Dwell times 4. Data rates The IEEE 802. 1 standard specifies data rates of 1 Mbps and 2 Mbps and Open-Air (a standard created by the now defunct Wireless LAN Interoperability Forum) specifies data rates of 800 kbps and 1. 6 Mbps. In order for a frequency hopping system to be 802. 11 or Open-Air compliant, it must give way in the 2. 4 GHz ISM band (which is defined by the FCC as being from 2. 4000 GHz to 2. 5000 GHz). Both standards allow operation in the range of 2. 4000 GHz to 2. 4835 GHz. Channels A frequency hopping system will operate using a specified hop pattern called a leave. Frequency hopping systems typically use the FCCs 26 standard hop patterns or a subset thereof.Some frequen cy hopping systems will allow custom hop patterns to be created, and others even allow synchronization between systems to completely eliminate collisions in a co-located environment. Figure 2. 10 Co-located frequency hopping system Though it is possible to have as many as 79 synchronized, co-located access points, with this many systems, all(prenominal) frequency hopping radio would require precise synchronization with all of the others in order not to interfere with (transmit on the same frequency as) another frequency hopping radio in the area. The cost of such a set of systems is prohibitive and is generally not considered an option.If synchronized radios are used, the expense tends to dictate 12 co-located systems as the maximum. 15 If non-synchronized radios are to be used, then 26 systems can be co-located in a wireless LAN this number is considered to be the maximum in a medium- craft wireless LAN. Increasing the traffic significantly or routinely transferring large files pl aces the practical limit on the number of co-located systems at about 15. More than 15 co-located frequency-hopping systems in this environment will interfere to the extent that collisions will begin to reduce the aggregate throughput of the wireless LAN.Dwell Time In frequency hopping systems, it must transmit on a specified frequency for a time, and then hop to a different frequency to continue transmitting. When a frequency hopping system transmits on a frequency, it must do so for a specified amount of time. This time is called the dwell time. Once the dwell time has expired, the system will switch to a different frequency and begin to transmit again. Suppose a frequency hopping system transmits on only two frequencies, 2. 401 GHz and 2. 402 GHz. The system will transmit on the 2. 01 GHz frequency for the duration of the dwell time100 milliseconds (ms), for example. After 100ms the radio must change its transmitter frequency to 2. 402 GHz and send information at that frequency f or 100ms. Hop Time When considering the hopping action of a frequency hopping radio, dwell time is only part of the story. When a frequency hopping radio jumps from frequency A to frequency B, it must change the transmit frequency in one of two ways. It either must switch to a different circuit tuned to the brisk frequency, or it must change some element of the current circuit in order to tune to the new frequency.In either case, the process of changing to the new frequency must be complete before transmission can resume, and this change takes time due to electrical latencies inherent in the circuitry. There is a small amount of time during this frequency change in which the radio is not transmitting called the hop time. The hop time is measured in microseconds (s) and with relatively long dwell times of around 100-200 ms, the hop time is not significant. A typical 802. 11 FHSS system hops between impart in 200-300 s. With very short dwell times of 500 600s, like those being used in some frequency hopping systems such as Bluetooth, hop ime can become very significant. If we look at the effect of hop time in terms of data throughput, we discover that the longer the hop time in relation to the dwell time, the slower the data rate of bits being transmitted. 2. 2. 5 Direct season Spread Spectrum (DSSS) Direct sequence spread spectrum is very widely known and the most used of the spread spectrum types, owing most of its popularity to its ease of implementation and high data rates. The majority of wireless LAN equipment on the commercialise today uses DSSS technology.DSSS is a method of sending data in which the transmitting and receiving systems are both on a 22 MHz-wide set of frequencies. The wide channel enables devices to transmit more information at a higher data rate than current FHSS systems. 16 How DSSS Works DSSS combines a data signal at the sending station with a higher data rate bit sequence, which is referred to as a crisp ordinance or processi ng gain. A high processing gain increases the signals resistance to interference. The minimum linear processing gain that the FCC allows is 10, and most commercial products operate under 20.The IEEE 802. 11 working group has set their minimum processing gain requirements at 11. The process of direct sequence begins with a carrier being modulated with a ordinance sequence. The number ofchips-in the code will determine how much spreading occurs, and the number of chips per bit and the speed of the code (in chips per second) will determine the data rate. Direct Sequence Spread Spectrum (DSSS) Direct sequence spread spectrum is very widely known and the most used of the spread spectrum types, owing most of its popularity to its ease of implementation and high data rates.The majority of wireless LAN equipment on the market today uses DSSS technology. DSSS is a method of sending data in which the transmitting and receiving systems are both on a 22 MHz-wide set of frequencies. The wide ch annel enables devices to transmit more information at a higher data rate than current FHSS systems. How DSSS Works DSSS combines a data signal at the sending station with a higher data rate bit sequence, which is referred to as a chipping code or processing gain. A high processing gain increases the signals resistance to interference.The minimum linear processing gain that the FCC allows is 10, and most commercial products operate under 20. The IEEE 802. 11 working group has set their minimum processing gain requirements at 11. The process of direct sequence begins with a carrier being modulated with a code sequence. The number of-chips-in the code will determine how much spreading occurs, and the number of chips per bit and the speed of the code (in chips per second) will determine the data rate. Channels Unlike frequency hopping systems that use hop sequences to define the conduct, direct sequence systems use a more formulaic definition of channels. to from each one one channel is a contiguous band of frequencies 22 MHz wide and 1 MHz carrier frequencies are used just as with FHSS. Channel 1, for instance, operates from 2. 401 GHz to 2. 423 GHz (2. 412 GHz 11 MHz) channel 2 operates from 2. 406 to 2. 429 GHz (2. 417 11 MHz), and so forth. Figure 2. 11 illustrates this point. 17 Figure 2. 11 channel allocation and Spectral relationship The chart in Table 2. 1 has a complete list of channels used in the United States and Europe. The FCC specifies only 11 channels for non-licensed use in the United States. apiece of the frequencies listed in this chart are considered center frequencies.From this center frequency, 11 MHz is added and subtracted to get the useable 22 MHz wide channel. Easy to see that adjacent channels (channels directly next to severally other) would overlap significantly. Table 2. 1 DSSS channel frequency Assignment Channel ID 1 2 3 4 5 6 7 8 9 10 11 FCC Channel Frequencies GHz 2. 412 2. 417 2. 422 2. 427 2. 432 2. 437 2. 442 2. 447 2. 452 2. 457 2. 462 ETSI Channel Frequencies GHz N/A N/A 2. 422 2. 427 2. 432 2. 437 2. 442 2. 447 2. 452 2. 457 2. 462 To use DSSS systems with overlapping channels in the same physical blank shell would cause interference between the systems.DSSS systems with overlapping channels should not be co-located because there will close always be a drastic or complete reduction in throughput. Because the center frequencies are 5 MHz apart and the channels are 22 MHz wide, channels should be co-located only if the channel numbers are at least five apart channels 1 and 6 do not overlap, channels 2 and 7 do not overlap, etc. There is a maximum of three co-located direct sequence systems possible because channels 1, 6 and 11 are the only divinatoryly non-overlapping channels. The 3 non-overlapping channels are illustrated in Figure 2. 2 18 Figure 2. 12 DSSS non-overlapping Channel 2. 2. 6 Comparing FHSS and DSSS Both FHSS and DSSS technologies have their advantages and disadvantages, and it incumbent on the wireless LAN administrator to give each its due weight when deciding how to implement a wireless LAN 4. This section will cover some of the factors that should be discussed when determining which technology is appropriate for your organization, including 1. Narrowband interference 2. Co-location 3. Cost 4. Equipment compatibility 5. Data rate and throughput 6. Security 7.Standards support Narrowband Interference The advantages of FHSS include a greater resistance to narrow band interference. DSSS systems may be affected by narrow band interference more than FHSS because of the use of 22 MHz wide contiguous bands instead of the 79 MHz used by FHSS. This fact may be a serious consideration if the proposed wireless LAN site is in an environment that has such interference present. Co-location An advantage of FHSS over DSSS is the ability for many more frequency hopping systems to be co-located than direct sequence systems.Since frequency hopping systems are-frequency ag ile-and make use of 79 discrete channels, frequency hopping systems have a co-location advantage over direct sequence systems, which have a maximum co- location of 3 access points. 19 Figure 2. 13 Co-location Comparison However, when calculating the hardware costs of an FHSS system to get the same throughput as a DSSS system, the advantage quickly disappears. Because DSSS can have 3 co-located access points, the maximum throughput for this configuration would be 3 access points ? 1 Mbps = 33 Mbps At about 50% of rated bandwidth, the DSSS system throughput would be approximately 33 Mbps / 2 = 16. 5 Mbps To achieve roughly the same rated system bandwidth using an IEEE 802. 11 compliant FHSS system would require 16 access points ? 2 Mbps = 32 Mbps At roughly 50% of rated bandwidth, the FHSS system throughput would be approximately 32 Mbps / 2 = 16 Mbps In this configuration, an FHSS system would require 13 additional access points to be purchased to get the same throughput as the DSSS system. Also, additional installation services for these units, cables, connectors, and antennas would all need to be purchased.Cost When implementing a wireless LAN, the advantages of DSSS may be more compelling than those of FHSS systems, particularly when driven by a tight budget. The cost of implementing a direct sequence system is far less than that of a frequency hopping system. DSSS equipment is widely available in todays marketplace, and its rapid adoption has helped in capricious down the cost. Only a few short years ago, equipment was only affordable by enterprise customers. Today, very good quality 802. 11b compliant PC cards can be purchased for under $100.FHSS cards complying with either the 802. 11 or Open-Air standards typically run between $150 and $350 in today market depending on the manufacturer and the standards to which the cards s adhere. 20 Equipment compatibility and availability The Wireless Ethernet Compatibility Alliance (WECA) provides testing of 802. 1 1b compliant DSSS wireless LAN equipment to ensure that such equipment will operate in the presence of and interoperate with other 802. 11b DSSS devices. The interoperability standard that WECA created and now uses is called Wireless Fidelity, or Wi-Fi, and hose devices that pass the tests for interoperability are-Wi-Fi compliant-devices. Devices so deemed are allowed to affix the Wi-Fi logo on the related marketing material and devices themselves showing that they have been tested and interoperate with other Wi-Fi compliant devices. There are no such compatibility tests for equipment that uses FHSS. There are standards such as 802. 11 and Open-Air, but no organization has stepped forward to do the same kind of compatibility testing for FHSS as WECA does for DSSS. Due to the immense popularity of 802. 11b compliant radios, it is much easier to obtain these units.The demand seems only to be growing for the Wi-Fi compliant radios while the demand for FHSS radios has remained fairly st eady, even decreasing to some degree over the foregone year. Data rate and throughput The latest frequency hopping systems are slower than the latest DSSS systems mostly because their data rate is only 2 Mbps. Though some FHSS systems operate at 3 Mbps or more, these systems are not 802. 11 compliant and may not interoperate with other FHSS systems. FHSS and DSSS systems have a throughput (data actually sent) of only about half of the data rate.When testing the throughput of a new wireless LAN installation, achieving 5-6 Mbps on the 11 Mbps backing for DSSS or 1 Mbps on the 2 Mbps setting common using DSSS. When wireless frames are transmitted, there are pauses between data frames for control signals and other overhead tasks. With frequency hopping systems, this interframe spacing is longer than that used by direct sequence systems, causing a slow-down in rate that data is actually sent (throughput). Additionally, when the frequency hopping system is in the process of changing the transmit frequency, no data is sent.This translates to more lost throughput, albeit only a minor amount. Some wireless LAN systems use proprietary physical layer protocols in order to increase throughput. These methods work, yielding throughputs as high as 80% of the data rate, but in so doing, sacrifice interoperability. Security It is widely touted-and is a myth-that frequency hopping systems are inherently more secure than direct sequence systems. The first fact that disproves this myth is that FHSS radios are only produced by a minimal number of manufacturers. Of this small list of manufacturers, all of them adhere to standards such as 802. 1 or Open-Air in order to sell their products effectively. Second, each of these manufacturers uses a standard set of hop sequences, which generally comply with a pre-determined list, produced by the standards body (IEEE or WLIF). These 2 items together make breaking the code of hop sequences relatively simple. 21 Other reasons that make fi nding the hop sequence quite simple is that the channel number is broadcasted in the clear with each beacon. Also, the MAC address of the transmitting access point can be seen with each beacon (which indicates the manufacturer of the radio).Some manufacturers allow the administrator the flexibility of define custom hopping patterns. However, even this custom capability is no level of security since fairly unsophisticated devices such as spectrum analyzers and a standard laptop computer can be used to track the hopping pattern of a FHSS radio in a matter of seconds. Standards Support DSSS has gained wide acceptance due to low cost, high speed, WECA Wi-Fi s interoperability standards, and many other factors. This market acceptance will only accelerate due to the patience moving toward newer, faster DSSS systems such as the new 802. 1g and 802. 11a compliant wireless LAN hardware. WECA new Wi-Fi5 s interoperability standard for 5 GHz DSSS systems operating in the UNII bands will help move the industry along even faster in the same direction it is already headed. The new standards for FHSS systems include Home RF 2. 0 and 802. 15 (in support of WPANs such as Bluetooth), but none for advancing FHSS systems in the enterprise. 2. 2. 7 BPSK In BPSK, the phase of the carrier is varied to represent double star 1 or 0 . Both peak amplitude and frequencies remain constant as the phase changes.For example, if a phase of 0 represents binary 0, then the phase clxxx represents binary 1. the phase of the signal during each bit duration is constant. And its value depends on the bit (0 or 1). Figure 2. 14 shows a conceptual view of BPSK. BPSK is also known as 2-PSK. because two different phases (0 and 180) are used. The table below shows BPSK which makes the relationship of phase to bit value. Bit 0 1 Phase 0? 180? Figure 2. 14 BPSK. 2. 2. 8 QPSK The diagram for the signal is given in Figure 2. 15. A phase of 0 now represents 00 90 represents 01 180 represents10 and 270 repre sents 11. This technique is called QPSK.The pair of bits represented by each phase is called a dibit. 22 Bit 00 01 10 11 Figure 2. 15 QPSK. Phase 0? 90? 180? 270? 2. 2. 9 QAM QAM is a Combination of ASK and PSK so that a maximum contrast between each signal unit (bit, dibit, tribit, and so on) is achieved. QAM takes the advantages of the fact that it is possible to send two different signals simultaneously on the same carrier frequency . by using two copies of the carrier frequency. One shifted by 90 with respect to the other. For QAM, each carrier is ASK modulated. The two independent signals are simultaneously transmitted over the same medium.In QAM the number of amplitude shifts is fewer than the number of phase shifts. Because amplitude changes are susceptible to noise and require greater shift distances than do phase changes, the number of phase shifts used by a QAM system is always larger than the number of amplitude shifts. 5 Figure 2. 16 QAM. 23 2. 2. 10 Orthogonal Frequency course of instruction Multiplexing (OFDM) Orthogonal Frequency division Multiplexing offers the highest data rates and maximum resistance to interference and corruption of all the signal manipulation techniques in use in 802. 1 today 5. Although it is not considered a spread spectrum technique by the FCC, OFDM shares many qualities with spread spectrum communicators, including using a low transmit power and wider-than-necessary bandwidth. OFDM is used to provide data rates up to 54 Mbps in 802. 11a and 802. 11g. How OFDM Works OFDM achieves high data rates by squeezing a large number of confabulation Channels into a given frequency band. Normally, two communication channels must be separated by a certain amount of bandwidth or they overlap and interfere.Specially, each Channel has harmonics that extend up and down the frequency space, decreasing in amplitude as they get farther from the channels fundamental signal. Even if two channels are non-overlapping, their harmonics may ove rlap and the signal can be corrupted. An OFDM communicator can place adjacent communication channels very precisely in the frequency space in such a way that the channels harmonics exactly cancel each other, effectively go away only the fundamental signals. OFDM achieves high data rates by dividing a single communication channel into a large number of closely-spaced, small bandwidth sub-carriers.Each sub-carrier individually has a relatively low data rate, but by transmitting data in parallel on all sub-carriers simultaneously, high data rates can be achieved. Figure 2. 17 OFDM frequency plot. Figure 2. 17 shows an example of a frequency spectrum for an OFDM transmitter. Each of the peaks represents a single sub-carrier, and the sub-carriers together make up the communications channel. The sub-carriers are precisely aligned so that the zero-points of their harmonics overlapped exactly. The majority of the harmonic energy will cancel out, leaving just the sub-carriers. 4 CHAPTER 3 R F overture and Accessories 25 Chapter 3 RF Antenna and Accessories 3. 1 Introduction Antennas are most often used to increase the range of wireless LAN systems, but proper antenna selection can also enhance the security of your wireless LAN. A properly chosen and positioned antenna can reduce the signal leaking out of workspace, and make signal interception extremely difficult. 3. 2 RF Antennas An RF antenna is a device used to convert high frequency (RF) signals on a transmission line (a cable or waveguide) into propagated waves in the air 6.The electrical fields emitted from antennas are called beams or lobes. Antenna convert electrical energy into RF waves in the case of a transmitting antenna, or RF waves into electrical energy in the case of a receiving antenna. The physical dimensions of an antenna, such as its length, are directly related to the frequency at which the antenna can propagate waves or receive propagated waves. The physical structure of an antenna is directly re lated to the Shape of the area in which it concentrates most of its related RF energy. There are three generic categories of RF antennas 1.Omni-directional 2. fishing gear-directional 3. Highly-directional Each category has multiple types of antennas, each having different RF characteristics and appropriate uses. As the gain of an antenna goes up, the coverage area narrows so that high-gain antennas offer longer coverage areas than low-gain antennas at the same input power level. 3. 2. 1 Omni-directional (Dipole) Antennas The dipole is an omni- directional antenna, because it radiates its energy equally in all directions around its axis. Dipole antenna is unsophisticated to design dipole antenna is standard equipment on most access points.Directional antennas concentrate their energy into a cone, known as a beam. Figure 3. 1 Dipole doughnut 26 Figure 3. 1 shows that the dipole radiant energy is concentrated into a region that s looks like a doughnut, with the dipole vertically t hrough the hole of the doughnut. The signal from an omni-directional antenna radiates in a 360-degree horizontal beam. If an antenna radiates in all directions equally (forming a sphere), it is called an isotropic radiator, which is the theoretical reference for antennas, but rather, practical antennas all have some type of gain over that of an isotropic radiator.The dipole radiates equally in all directions around its axis, but does not radiate along the length of the wire itself hence the doughnut pattern. The side view of a dipole radiator as it radiates waves in Figure 3. 2. Figure 3. 2 Dipole-side view If a dipole antenna is placed in the center of a single floor of a multistory building, most of its energy will be radiated along the length of that floor, with some significant fraction sent to the floors above and below the access point. Figure 3. 3 shows examples of some different types of omni-directional antennas. Figure 3. 3 Sample omni-directional antennaFigure 3. 4 show s a two-dimensional example of the top view and side view of a dipole antenna. Figure 3. 4 Coverage area of an omni-directional antenna High-gain omni-directional antennas offer more horizontal coverage area, but the vertical coverage area is reduced, as can be seen in Figure 3. 5. 27 Figure 3. 5 Coverage area of high gain omni-directional antennas This characteristic can be an important consideration when mounting a high-gain omni antenna indoors on the ceiling. If the ceiling is too high the coverage area may not reach the floor, where the users are located.Usages Omni-directional antennas are used when coverage in all directions around the horizontal axis of the antenna is required. Omni-directional antennas are most effective where large coverage areas are needed around a central point. For example, placing an omni- directional antenna in the middle of a large, open room would provide good coverage. Omni-directional antennas are usually used for point-tomultipoint designs with a hub-n-spoke topology. Used outdoors, an omni-directional antenna should be placed on top of a structure (such as a building) in the middle of theFigure 3. 6 Point to multipoint link coverage area. For example, on a college campus the antenna might be placed in the center of the campus for the greatest coverage area. When used indoors, the antenna should be placed at the middle of the building or desired coverage area, near the ceiling, for optimum coverage. Omni-directional antennas emit a large coverage area in a circular pattern and are suitable for warehouses or tradeshows where coverage is usually from one corner of the building to the other. 3. 2. 2 Semi directional AntennaSemi directional antennas direct the energy from the transmitter significantly more in one particular direction rather than the furnish circular pattern that is common with the omni- directional antenna Semi-directional antennas come in many different styles and shapes. Some semi- directional antennas type s frequently used with wireless LANs are Patch, Panel, and Yagi (pronounced YAH-gee) antennas. All of these antennas are generally flat and designed for wall mounting. Each type has different coverage characteristics. Figure 3. shows some examples of semidirectional antennas. 28 Figure 3. 7 Sample semi-directional antenna Semi-directional antennas often radiate in a hemispherical or cylindrical coverage pattern as can be seen in Figure 3. 8. Figure 3. 8 Coverage area of a semi-directional antenna Usages Semi-directional antennas are ideally suited for short and medium range bridging. For example, two office buildings that are across the street from one another and need to share a network connection would be a good scenario in which to implement semidirectional antennas.In a large indoor space, if the transmitter must be located in the corner or at the end of a building, a corridor, or a large room, a semi-directional antenna would be a good choice to provide the proper coverage. Fig ure 3. 9 illustrates a link between two buildings using semi-directional antennas. Figure 3. 9 Point to point link using semi-directional antenna In some cases, semi-directional antennas provide such long-range coverage that they may eliminate the need for multiple access points in a building.For example, in a long hallway, several access points with omni antennas may be used or perhaps only one or two access points with properly placed semi-directional antennas saving the customer a significant amount of money. In some cases, semi- directional antennas have back and side lobes that, if used effectively, may further reduce the need for additional access points. 29 3. 2. 3 Highly directional antenna Highly-directional antennas emit the most narrow signal beam of any antenna type and have the greatest gain of these three groups of antennas.Highly-directional antennas are typically concave, dish-shaped devices, as can be seen Figures 3. 10 and 3. 11. These antennas are ideal for long distance, point-to-point wireless links. Some models are referred to as parabolic dishes because they resemble small satellite dishes. Others are called grid antennas due to their perforated design for resistance to wind loading. Figure 3. 10 sample of a highly directional antenna Figure 3. 11 sample of a highly directional grid antenna Figure 3. 12 Radiation pattern of a highly directional antennaUsages High-gain antennas do not have a coverage area that client devices can use. These antennas are used for point-to-point communication links, and can transmit at distances up to 25 miles. Potential uses of highly directional antennas might be to connect two buildings that are miles away from each other but have no obstructions in their path. Additionally, these antennas can be aimed directly at each other within a building in order to blast through an obstruction. This setup would be used in order to get network connectivity to places that cannot be wired and where normal wireless net works will not work. 0 3. 2. 4 Antenna Gain An antenna element without the amplifiers and filters typically associated with it is a passive device. There is no conditioning, amplifying, or manipulating of the signal by the antenna element itself. The antenna can create the effect of amplification by virtue of its physical shape. Antenna amplification is the result of focusing the RF radiation into a tighter beam, just as the bulb of a flashlight can be focused into a tighter beam creating a seemingly brighter light source that sends the light further.The focusing of the radiation Measured by way of beam widths, which are measured in degrees horizontal and vertical. For example, an omni-directional antenna has a 360-degree horizontal beam width. By limiting the 360-degree beam width into a more focused beam of, say, 30 degrees, at the same power, the RF waves will be radiated further. This is how patch, panel, and Yagi antennas (all of which are semi-directional antennas) are designe d. Highly directional antennas take this theory a step further by very tightly focusing both horizontal and vertical beam widths to maximize distance of the propagated wave at low power. . 2. 5 Intentional Radiator As defined by the Federal Communication Commission (FCC), an intentional radiator is an RF device that is specifically designed to generate and radiate RF signals. In terms of hardware, an intentional radiator will include the RF device and all cabling and connectors up to, but not including, the antenna, as illustrated in Figure 3. 13 below. Figure 3. 13 Intentional Radiator Any reference to power output of the Intentional Radiator refers to the power output at the end of the last cable or connector before the antenna.For example, consider a 30- milliwatt transmitter that loses 15 milliwatts of power in the cable and another 5 milliwatts from the connector at the antenna. The power at the intentional radiator would be 10 milliwatts. As an administrator, it is your respon sibility to ascertain the FCC rules relating to Intentional Radiators and their power output. Understanding how power output is measured, how much power is allowed, and how to calculate these values are all covered in this book. FCC regulations concerning output power at the Intentional Radiator and EIRP are found in Part 47 CFR, 1 3. 2. 6 Equivalent Isotropically Radiated Power (EIRP) EIRP is the power actually radiated by the antenna element, as shown in Figure 3. 14. This concept is important because it is regulated by the FCC and because it is used in calculating whether or not a wireless link is viable. EIRP takes into account the gain of the antenna. Figure 3. 14 Equivalent Isotropically Radiated Power Suppose a transmitting station uses a 10-dBi antenna (which amplifies the signal 10fold) and is fed by 100 mill watts from the intentional radiator.The EIRP is 1000 mW, or 1 Watt. The FCC has rules defining both the power output at the intentional radiator and the antenna eleme nt. 3. 3 RF Accessories When wireless LAN devices connect together, the appropriate cables and accessories need to purchase that will maximize throughput, minimize signal loss, and, most importantly, allow making connections correctly. Different types of accessories are needed in a wireless LAN design. 7 1. RF Amplifiers 2. RF Attenuators 3. Lightning Arrestors 4. RF Connectors 5. RF melodic lines 3. 3. 1 RF AmplifiersAn RF amplifier is used to amplify, or increase the amplitude of, RF signal, which is measured in +dB. An amplifier will be used when compensating the loss incurred by the RF signal, either due to the distance between antennas or the length of cable from a wireless infrastructure device to its antenna. Most RF amplifiers used with wireless LANs are powered using DC voltage fed onto the RF cable with an injector near the RF signal source (such as the access point or bridge). Sometimes this DC voltage used to power RF amplifiers is called phantom voltage because the RF amplifier seems to magically power up.This DC injector is powered using AC voltage from a wall outlet, so it might be located in a wiring closet. In this scenario, the RF cable carries 32 both the high frequency RF signal and the DC voltage necessary to power the in-line amplifier, which, in turn, boosts the RF signal amplitude. Figure 3. 15 shows an example of an RF amplifier (left), and how an RF amplifier is mount on a pole (right) between the access point and its antenna. Figure 3. 15 A sample of a fixed gain Amplifier RF amplifiers come in two types unidirectional and bi-directional.Unidirectional amplifiers compensate for the signal loss incurred over long RF cables by increasing the signal level before it is injected into the transmitting antenna. Bi-directional amplifiers boost the effective sensitivity of the receiving antenna by amplifying the received signal before it is fed into the access point, bridge, or client device. conformation and trouble RF amplifiers used with wireless LANs are installed in series with the main signal path seen below in Figure 3. 16. Amplifiers are typically attach to a solid surface using screws through the amplifiers flange plates.Configuration of RF amplifiers is not generally required unless the amplifier is a variable RF amplifier. If the amplifier is variable, the amplifier must be configured for the proper amount of amplification required, according to RF math calculations. The manufacturer user manual will s explain how to architectural plan or configure the amplifier. Figure 3. 16 RF amplifier placement in the wireless LAN system 3. 3. 2 RF Attenuators An RF attenuator is a device that causes precisely measured loss (in dB) in an RF signal. While an amplifier will increase the RF signal, an attenuator will decrease it.Consider the case where an access point has a fixed output of 100mW, and the only antenna available is an omni-directional antenna with +20 dBi gain. Using this equipment together would violate FCC rules for power output, so an attenuator could be added to decrease the RF signal down to 30mW before it entered the antenna. This configuration would put the power output within FCC parameters. Figure 3. 17 shows examples of fixed-loss RF attenuators with BNC connectors (left) and SMA connectors (right). Figure 3. 18 shows an example of an RF step attenuator. 33 Figure 3. 7 Sample of a fixed loss Amplifier Figure 3. 18 A sample of a RF step attenuator ( inconsistent loss) Configuration and Management Figure 3. 19 shows the proper placement in a wireless LAN for an RF attenuator, which is directly in series with the main signal path. Fixed, coaxial attenuators are connected directly between any two-connection points between the transmitter and the antenna. For example, a fixed, coaxial antenna might be connected directly on the output of an access point, at the input to the antenna, or anywhere between these two points if multiple RF cables are used.Variable antennas are general ly mounted to a surface with screws through their flange plates or simply placed in a wiring closet on a shelf. Configuration of RF attenuators is not required unless a variable attenuator is used, in which case, the amount of attenuation required is configured according to your RF calculations. Configuration instructions for any particular attenuator will be included in the manufacturer user manual. s Figure 3. 19 RF attenuator placement in a wireless LAN 3. 3. 3 Lightning Arrestors A lightning arrestor is used to shunt transient current into the ground that is caused by lightning.Lightning arrestors are used for protecting wireless LAN hardware such as access points, bridges, and workgroup bridges that are attached to a coaxial transmission line. Coaxial transmission lines are susceptible to surges from close lightning strikes. Lightning arrestor are only needed for outdoor antennas that are 34 Susceptible to lighting sticks in the vicinity. They are not necessary for indoor ante nnas because of the existing building ground. A lightning arrestor can generally shunt surges up to 5000 Amperes at up to 50 volts. Lightning arrestor performs the following function 1.Lightning strikes a nearby object 2. Transient current are induced in the antenna or the RF transmission line 3. The lightning arrestor senses these currents and immediately ionizes the gases held internally to cause a short (a path of almost no resistance) directly to earth ground. Figure 3. 20 Lightning Arrestors installed in a network 3. 3. 4 RF Connectors RF connectors are specific types of connection devices used to connect cables to devices or devices to devices. Traditionally, N, F, SMA, BNC, and TNC connectors (or derivatives) have been used for RF connectors on wireless LANs.In 1994, the FCC and DOC (Canadian Department of Communications) ruled that connectors for use with wireless LAN devices should be proprietary between manufacturers 7. For this reason, many variations on each connector ty pe exist such as 1. N-type 2. Reverse polarity N-type 3. Reverse threaded N-type Figure 3. 21 Sample N-type and SMA Connector 35 Choosing an RF Connector There are five things that should be considered when purchasing and installing any RF connector, and they are similar in nature to the criteria for choosing RF amplifiers and attenuators. . The RF connector should match the impedance of all other wireless LAN components (generally 50 ohms). 2. slam how much insertion loss each connector inserted into the signal path causes. The amount of loss caused will factor into your calculations for signal strength required and distance allowed. 3. Know the upper frequency limit (frequency response) specified for the particular connectors. This point will be very important as 5 GHz wireless LANs become more and more common. Some connectors are rated only as high as 3 GHz, which is fine for use with 2. GHz wireless LANs, but will not work for 5 GHz wireless LANs. Some connectors are rated only up to 1 GHz and will not work with wireless LANs at all, other than legacy 900 MHz wireless LANs. 4. Beware of bad quality connectors. First, always consider purchasing from a reputable company. Second, purchase only high-quality connectors made by name-brand manufacturers. This kind of purchasing particularity will help eliminate many problems with sporadic RF signals, VSWR, and bad connections. 5. Make sure you know both the type of connector (N, F, SMA, etc. ) that you need and the sex of the connector.Connectors come in male and female. Male connectors have a center pin, and female connectors have a center receptacle. 3. 3. 5 RF Cables Proper cables are needed for connecting an antenna to an access point or wireless bridge. Below are some criteria to be considered in choosing the proper cables for your wireless network. 1. Cables introduce loss into a wireless LAN, so make sure the shortest cable length necessary is used. 2. devise to purchase pre-cut lengths of cable with pre -installed connectors. Doing minimizes the possibility of bad connections between the connector and the cable.Professional manufacturing practices are almost always superior to cables manufactured by untrained individuals. 3. attend for the lowest loss cable available at your particular price range (the lower the loss, the more expensive the cable). Cables are typically rated for loss in dB/100-feet. The table in Figure 5. 29 illustrates the loss that is introduced by adding cables to a wireless LAN. 4. Purchase cable that has the same impedance as all of your other wireless LAN components (generally 50 ohms). 5. The frequency response of the cable should be considered as a primary decision factor in your purchase.With 2. 4 GHz wireless LANs, a cable with a rating of at least 2. 5 GHz should be used. With 5 GHz wireless LANs, a cable with a rating of at least 6 GHz should be used. 36 Table 3. 1 Coaxial Cable attenuation ratings LMR Cable 100A 195 200 240 300 400 400UF 500 600 600UF 900 1200 1700 30 3. 9 2. 0 1. 8 1. 3 1. 1 0. 7 0. 8 0. 54 0. 42 0. 48 0. 29 0. 21 0. 15 50 5. 1 2. 6 2. 3 1. 7 1. 4 0. 9 1. 1 0. 70 0. 55 0. 63 0. 37 0. 27 0. 19 150 8. 9 4. 4 4. 0 3. 0 2. 4 1. 5 1. 7 1. 2 1. 0 1. 15 0. 66 0. 48 0. 35 220 10. 9 5. 4 4. 8 3. 7 2. 9 1. 9 2. 2 1. 5 1. 2 1. 0. 80 0. 59 0. 43 450 15. 8 7. 8 7. 0 5. 3 4. 2 2. 7 3. 1 2. 2 1. 7 2. 0 1. 17 0. 89 0. 63 900 22. 8 11. 1 9. 9 7. 6 6. 1 3. 9 4. 5 3. 1 2. 5 2. 9 1. 70 1. 3 0. 94 1500 30. 1 14. 5 12. 9 9. 9 7. 9 5. 1 5. 9 4. 1 3. 3 3. 8 2. 24 1. 7 1. 3 1800 33. 2 16. 0 14. 2 10. 9 8. 7 5. 7 6. 6 4. 6 3. 7 4. 3 2. 48 1. 9 1. 4 2000 35. 2 16. 9 15. 0 11. 5 9. 2 6. 0 6. 9 4. 8 3. 9 4. 5 2. 63 2. 0 1. 5 2500 39. 8 19. 0 16. 9 12. 9 10. 4 6. 8 7. 8 5. 5 4. 4 5. 1 2. 98 2. 3 1. 7 37 CHAPTER 4 Wireless LAN 38 Chapter 4 Wireless LAN 4. 1 Wireless LAN (WLAN) 4. 1. 1 Wireless LANLinking of t

History vs. Hollywood Essay

rain cloud Hollywood vs. History Glory is a movie close the 54th Massachusetts Infantry Regiment, one of the starting line official only portentous units in the United States during the Civil War. Its an inspirational story of how a childly Union soldier, Robert Gould Shaw, is offered the chance to address an army unit that will change non only his life, but the lives of numerous other Americans. Glory does a wide Job of capturing many of the feelings towards the black soldiers during the Civil War. The film is based off of the writings of Robert Gould Shaw, from letters he sent to his friends and family members.Most of the events in the movie re depicted very closely to how they actually happened. Director Edward Zwick tried to keep the movie as historically accurate as possible but, as many history movies do, Glory left out almost important details. Shaws parents were both well-known abolitionist, and in Glory, so is he. Truthfully, Shaw didnt share his parents passion f or foregoing the slaves. Shaw fagged most of his youth studying and traveling in Europe. Eventually he attended Harvard, but ended up dropping out. Not long afterwards leaving Harvard, the war began and Shaw found his purpose.He immediately Joined the army and headed to the fght. After nearly 3 years, Shaw reached the rank of Captain. This is when he received the opportunity to lead the 54th. In the film, Shaw is asked by Massachusetts Governor fundament A. Andrew to lead the 54th while at a dinner party, and after little hesitation, he gladly accepts. In reality, Shaw wasnt Andrews first choice for the position, nor was Shaw ever at said dinner party. Shaw was actually approached by his father at a Union camp. At first Shaw declined, past after a few days of thought and pressure from his mother, he reluctantly accepted.In the movie, Shaw is promoted to Colonel immediately after accepting the position, but soldiery ecords show he was a major for several months until the regime nt grew in numbers. In Glory, Shaw asks his best friend, Cabot Forbes, to be his Major. In reality, Forbes doesnt actually exist, or never did. The writers of Glory combined two of the recipients of Shaws letters names together and created the character of Cabot Forbes. In fact, of the main characters in Glory, Shaw is the only one who was a real person. Silas Trip, John Rawlins, and the rest of Glorys stars are all composite characters.On that note, the movie gives the idea that most of the members of the 4th were runaway slaves, while nearly all of the members were actually free blacks from the North. Frederick Douglass makes in appearance in the movie, but his two sons, who were actually members of the 54th, do not. Going back to Shaws feelings about the 54th, Shaw was, at first, dubious. After working with the men and realizing that they could fght save as well as clean-living soldiers, he grew to respect them. Shaw became eager to get his men into action, so he could prove wh at they were capable of.Shaw later learns that the black soldiers were to be paid less than the white ones. In the movie, Shaw announces this to the regiment, and Private Silas Trip, a former slave who escaped his masters, begins protesting and gets all of the men to tear up their paychecks and boycott. Shaw then says If you men will take no pay, then none of us will. , and tears up his check as well. In reality, Shaw was the one who led the boycott, refusing all wages until the problem was fixed. In the movie, Shaw spends a lot ot time tgnting to get unitorms and shoes tor his soldiers.The unitorms eventually arrive, but the shoes do not. Shaw has to go to one of his superiors and represent for the shoes. There is a moment where the colored men escort Shaw to the door and stand watch in a comical way. This scene shows that Shaw has truly create a bond with his men, but is really for the audiences pleasure. Nothing is written of this dispute, though there is no doubt was an actua l problem. Shaw married Annie Kneeland Haggerty, unspoiled days before the 54th is sent to the South for service, which is never mentioned in the film.There is another scene in the movie that is clearly for the audience, but it does have some truth behind it. When the 54th is marching south, they run into a regiment of white soldiers, and a quarrel breaks ut between Private Trip and some of the white men. Rawlins steps in to stop the fght and one of the white men is about to be disciplined, but Rawlins says that there is no need. This scene is displays the harsh criticism the fifth received, even from their own side, but it also gives a halo effect to Rawlins, who could have easily said nothing, and watched the soldier get punished.Later on go across the road the 54th meets up with Colonel James Montgomery, the colonel of another all black regiment. In the movie Montgomery was a racist and didnt discipline his men at all. While the eal Montgomery was noted to have discipline issue s, the movie probably took it way out of hand, Montgomery even shoots one of his men for misbehaving. Montgomery later takes the 54th to see some action, which actually meant looting and setting fire to a town of innocents.In the movie, Montgomery threatens Shaw to set fire to the town by saying hell take command of the 54th if he doesnt follow orders, so Shaw reluctantly orders the town to be burned. Shaw writes of this event in his letters, stating the civilian tribe of women and children were fired upon, forced from their homes, their possessions looted, and the town burned. Shaw also noted, On the way up, Montgomery threw several shells among the plantation buildings, in what seemed to me a very brutal way for he didnt know how many women and children there might be. Shaw even states he was ordered to set fire to the town but he refused.There is no mention of Montgomery threatening him, but he stated The reasons he gave me for destroying Darien were, that the Southerners must be made to feel that this was a real war, and that they were to be brush away by the hand of God, like the Jews of old. In theory it may seem all right to some, but when it comes to eing made the instrument of the Lords vengeance, I myself dont like it. Then he says, We are outlawed, and therefore not bound by the rules of regular warfare but that makes it until now revolting to wreak our vengeance on the innocent and defenseless. Soon after the ordeal with Montgomery, the 54th gets some real action, their first battle. They defeat the attacking rebels, suffering squirt casualties. Only two days after the skirmish, the 54th was chosen to lead an assault on Fort Wagner. In the movie, Shaw heroically volunteers, even though he knows that guide this ssault will cause great casualties to his regiment. Before the battle Shaw says If this man should fall, who will lift the flag and carry on? , and Thomas says hell do it. However, this wasnt actually how it happened.General George Crock ett Strong was the one who asked the question, and Shaw was the one who replied. During the assault in the movie, the water is to the left of the men, but really the 54th attacked with the water on their right. In the movie, the airplane pilot flag bearer is killed, as you would expect, and Shaw gets it He then stand up and snouts Forward Fi and is shot in the chest multiple times. According to the survivors, these were Shaws actual support words, and he hollered them shortly before being shot through the heart.After all of the carnage there is a scene where the Confederate soldiers drag Shaws be into a mass grave full of men from the 54th. This actually happens, though there is a little more to it. Confederate General Johnson Hagood told the Union he would not return Shaws body because he was leading colored men. This was intended to be an insult, but the Shaws didnt take it that way. Shaws father even said We would not have his body removed from where it lies surrounded by his rave and prone soldiers.We can imagine no holier place than that in which he lies, among his brave and devoted followers, nor wish for him better company what a body-guard he has Overall, Glory is a very good historical film. The writers didnt change too many facts or change the character of the actual people too much. Even though most of the main characters are fictional, the story was still almost completely factual. Glory has a great cast and a good plot. The story of the 54th Massachusetts is interesting and inspirational, and Glory is a must-watch movie for all ages.

DBQ Manchester Advice

Know what you need to address in your thesis and in your essay. It will help you to organize better if you can correctly assess the task that you are given. B) The rubric requires an explicitly stated thesis that addresses all split of the question. The prompt here is Identify the issues raised by the growth of Manchester and analyze the various reactions to those issues over the course of the 19thCentury. Here is an organization that tracks the prompt and will tierce to a solid thesis Issues Positive Reactions Negative Reactions 1 (massive groom) 6 (disease, bad health, bad morals) 8 (short life span) 3 (better lives) 9 (workshop to world) 10 (conditions improved) 2 (ugly, no beauty) 4 (dangerous discontent) 5 (man is made savage) 7 (is progress worth it? ) 11 (picture of filth) Here are some example theses that follow this group strike hardThe growth of Manchester led to many issues with varying reactions from different people. Romantics and activists saw very negative effects of the mass arbitration, while liberals tended to view the outcomes as overwhelmingly positive. As the growth of Manchester began to reach its peak many issues were brought to the forefront of debate such as health concerns and social conditions. Furthermore, these issues caused various

international business environment Legal considerations Essay

The sound aspects are important for the business choice. Laws are different in every country. Laws would regulate business practice, define the manner and set cut the rights and obligations. This made business fix to run within the border set by natural law and definitely affects the efficiency and profitability when running business in that country. The type of legal system.The legal system in Spain and Korea is ground on civil law, while court precedents are not granted official shape as law. The Spanish legal system is based on comprehensive legal codes and laws rooted in Roman law, as opposed to common law, which is based on precedent court rulings. Beca manipulation Japan occupied Korea from 1910 to 1945, the Korean legal system resembles the Japanese system. After the occupation however, there were attempts to adopt many aspects of the American legal system. It must be remembered that the first civilian governing body commenced only in 1992, and thereafter, increasingly mo re democratic reforms have taken place.1 Both countries use contracts and they are important for doing business in both countries. Neither Korea or Spain has advantage to the type of legal system. The protection of plaza rightThe definition of property right In economics, property usually refers to ownership (rights to the proceeds of output generated) and control over the use of the means of production. They may be owned privately, by the state, by those who use it, or held in common by society.2 The world property right index 2012 shows the differences between the countries and the countrys world ranking. southwestward Korea and Spain are both in the top 40 of the index. Spain ended this year on the 35th place and to the south Korea on the 40th place. The overall place off all the points together we can say that Spain comparingd with Korea is split in protection of property rights. In the figure on the next page we compare South Korea with Spain. The higher the score the bet ter protection of property right. Property right is important for running a business because the better protect the better is the stability of the company.Overall score South Korea vs. Spain in the inter guinea pig world index 2012The protection of intellectual propertyIntellectual property is a juridic concept which refers to creations of the mind for which exclusive rights are recognized. Under intellectual property law, owners are granted certain exclusive rights to a variety of intangible assets, such as musical, literary, and artistic works discoveries and inventions and words, phrases, symbols, and designs. Common types of intellectual property rights include copyright, trademarks, patents, industrial design rights and in some jurisdictions trade secrets. 4 South Korea has an government organization called KIPO. This is the governmental authority in charge of intellectual property in Korea. The mission of KIPO is to help Korea become an advanced country by providing legal and institutional administration for the creation and utilization of highly creative, value-added intellectual property and by promoting technological innovation and industrial development. In Spain the main law correct intellectual property protection is the 1996 Intellectual Property Law. With regard to industrial property, no single law covers all aspects. Instead, this is regulated by a software package of different laws, including the Patent Law, trade mark law and the law on the legal protection of industrial designs5 In the international property right index, South Korea and Spain score exactly the same and ends on the 27th place. There are 130 countries in the index so the both are trustful countries. putridnessA country where corruption is low is a really important factor to choose for a country. Corruption costs a lot of notes and affects the company negative. Korea has an independent commission against Corruption. The Korea Independent Commission Against Corruption is an independent commission that reports to the President in its fight against corruption and the consequent promotion of the novel administration of South Korea. In a coordinatedeffort with other monitoring agencies, also known proverbially as watchdogs, the KICAC is involved in producing policies and orchestrating birth control device activities.6 Spain has different organisations to fight against corruption. The Special Attorney Generals Office for the Repression of Economic Offences related with Corruption(ACPO) is the biggest and well known organisation in Spain. 7 fit in to the Corruption perception index Spain scores better than South Korea. The Corruption Perceptions Index ranks countries/territories based on how corrupt a countrys popular sector is perceived to be. It is a composite index, drawing on corruption-related data from expert and business surveys carried out by a variety of independent and redoubtable institutions. The difference between the two countries is not t hat big but Spain would be a saver option.Labour lawSpain and South Korea have both a minimum wage8. The minimum wage in Korea is freeze off than in Spain which is positive for the production costs. The maximum and average working hours in Spain are also lower than in South Korea. The maximum working hours in Spain are 40 hours a week and in South Korea 48. This is positive for the production because you can have longer days and the costs are lower as well. Forced labor and child labor are prohibited in both countries. In Korea children under the age of 18 may work under certain conditions. In spain the minimum age is 16. To do so, in Korea they require a specific employment certificate from the Labor Ministry, which is rarely issued because education is compulsory until the age of 14. Children under the age of 18 who wish to work require written laudation from their parents or guardians.Environmental lawSouth Korea is connected with the AECEN. This is the Asian Environmental Com pliance and Enforcement Network and there is an agreement between 16 Asian countries devote to improving cooperation with environmental laws in Asia. The mission of the Ministry of Environment in South Korea is to protect the national territory from threats of environmental pollution andto improve the quality of life sentence for the public. This includes ensuring the people of South Korea can enjoy the natural environment, clean water and clear skies. Furthermore, the Ministry aims to contribute to the global efforts to protect the Earth. In February 2008, the Korea Meteorological Administration became an interact of the Ministry of Environment to facilitate countermeasures against climate change In Spain the central government represents Spain in the European Union and transposes European legislation into Spanish law. It is responsible for adopting national legislation on the basic and common aspects of the environment. Both countries take the environment more than serious beca use it can effect business and people. The better and stricter the environmental law in the country the better and more effective you can produce your products. Nowadays the mission of most companies is to be green and fight against global warming. The regulations in Europe / Spain are more strict than in Asia what can be a reason to choose for Spain. The investment in expensive machinery and products to produce is peradventure higher at the start but with better machinery companies can produce more cleaner and more effective.Referenceshttp//en.wikipedia.org/wiki/Judiciary_of_Spainhttp//www.korealaw.com/sub/information/boardView.asp?brdId=overview&brdIdx=1&gotopage=1& wait=&search_string= http//www.nationsencyclopedia.com/economies/Asia-and-the-Pacific/Korea-South-WORKING-CONDITIONS.html