The System Dynamics Diagram Below Illustrates The...

EXPLANATION: The chosen organisation is Southside Takeaway, a small takeaway shop with approximately 5 employees. The system dynamics diagram below illustrates the interactions and activities of the business. The goal of the business is to produce fast, quality takeaway food that satisfies customer’s demands. The business has a sole trader structure but has had to rely on outside family investors for cash flow. This outside family investor arrangement means that bigger purchases can be made through consultation; each contributor has taken this opportunity to invest in the family legacy rather than receive profits. The choices of investors are deeply affected by economic fluctuations. Investors will have extra or less cash flow depending on the state of the economy at any given time and therefore will make further investment choices based on such. Stock management and purchasing are two closely linked internal factors in the business vital to providing quality products. Purchases are reliant on stock levels and must have management approval. Factors such as quality control, availability of produce, seasonal customer preferences, supplier availability and supplier relationships all play a role in the ability for the business to create value through these internal functions. Some of these external factors can be partially controlled; for example availability of produce and quality control can be managed by ensuring supplier relationships are strong. Stock management has aShow MoreRelatedUML - Unified Modeling Language5761 Words   |  24 PagesFIGURES V 1. INTRODUCTION 1 2. GENERAL VIEW OF UML 2 2.1 DEVELOPMENT OF UML 2 2.2 DEFINITION UML 3 2.3 OVERVIEW OF DIAGRAM TYPES 4 3. ACTIVITY DIAGRAM 6 3.1 FIELDS OF APPLICATION OF THE ACTIVITY DIAGRAM 6 3.2 NOTATION ELEMENTS OF THE ACTIVITY DIAGRAM 6 4. EXAMPLE OF USE IN LOGISTICAL PRACTICE 11 4.1 HOW TO USE AN ACTIVITY DIAGRAM 11 4.2 HOW TO MODIFY AN ACTIVITY DIAGRAM 13 4.2.1 Step 1 – describe the process 13 4.2.2 Step 2 – identify the elements 14 4.2.3 Step 3 – visualize the processRead MoreA Conceptual Model of an Erp System Using Uml3425 Words   |  14 PagesA Conceptual Model Of An ERP System Using UML Madhurima1(Lecturer), Madhulika (Lecturer) Apeejay College of Engineering, Gurgaon1 Flat No.306, kaveri apptt.,GH-4,Sec-21D, Faridabad-121001 Mob no. 09350350814,E-mail-10madhurima@gmail.com Apeejay College of Engineering, Gurgaon madhulikabhatia@gmail.com Abstract—In today’s competitive and ever changing environment every business demands paperless operations, a wireless communication of a result of fully transparent and automated operations ofRead MoreTeachers Attendance Monitoring System9215 Words   |  37 Pagesresearchers propose a teachers’ Attendance Monitoring System of Asian College of Technology that is more improved and more enhanced. This will provide the institution and the administration an automated system to be used for the daily records of instructor’s attendance place that will store and save the data ready anytime for any retrieving operations. This will also assure accuracy and certainty of information and is to be frequently updated. This system will also help them work more in less time and canRead MoreSingapore Economic Plan2065 Words   |  9 Pageswant. In addition, as Singapore has limited natural resource, energy and materials need to be imported. Business / Investor Roles: Job creation and sustainable profit The business of Singapore needs to ensure that they are profitable while setting up in Singapore. Cost and benefits need to be weight for them to operate in Singapore Potential conflict among stakeholders Business / Inventor. Residents and Government Government may implement policies that would require businesses to raiseRead MoreSingapore Economic Plan2052 Words   |  9 Pagesnot want. 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Some people like to take exam in a classroom is traditional manual examination because they are happy to sit there and have the teacher tell them what to learn, and when they get stuck, they are happy that there is someone there to help them, and they enjoyRead MoreSample Resume On Value Stream Mapping2219 Words   |  9 Pagesand improving on its lean journey. VSM shows the all the process from order entry to delivery. The value stream in a VSM is the point at which value is actually added to the product or service by changing its market form or function. Value adding activities can be things like: machining, assembly, welding, folding and so on. Scope of Value Stream Value Stream Map can be drown for three different levels: An extended level map as the view of the values stream at 60,000 feet, the facility level map atRead MoreDesign The Library Management System3008 Words   |  13 PagesManagement System, to include an evaluation of the processes towards improving the quality of the management software. The software will reflect all the requirements defined by the customer, documented in the included requirements documents. Further, included is an examination and evaluation of potential software development models for identification of those best suited to develop the software. Finally, an explanation of the testing plan utilized in testing the functionality of the system is includedRead MoreOoad Lab Manual10493 Words   |  42 PagesUML DIAGRAMS Date: UML DIAGRAMS There are three classifications of UML diagrams: †¢ Behavior diagrams. A type of diagram that depicts behavioral features of a system or business process. This includes activity, state machine, and use case diagrams as well as the four interaction diagrams. †¢ Interaction diagrams. A subset of behavior diagrams which emphasize object interactions. This includes communication, interaction overview, sequence, and timing diagrams. †¢ Structure diagrams. A typeRead MoreStarbucks Report5887 Words   |  24 Pages1 Application of Strategy Dynamics: Starbucks Corporation Pascal Gambardella, Ph.D. CSC 12708 Chilton Circle Silver Spring MD, 20904 301-346-5398 pgambard@csc.com Strategy Dynamics (Warren, 2008) provides a quantitative, resource-based approach to understanding a firm’s performance over time. This

Fast Food Restaurants And Obesity - 1528 Words

Do fast food restaurants contribute to obesity in America? One out of every four Americans stop by to eat fast food daily. Many people may not know this, but you would have to walk seven straight hours to burn off a super sized Coke, fry, and Big Mac. Sixty percent of all Americans are either overweight or obese. Did you also know that some fast food restaurants sell more toys than Toys-R-Us? Fast food restaurants contribute to obesity in America by promoting time-saving eating options, using celebrities to promote their products, and encouraging children to eat unhealthy food through clever marketing. Fast food restaurants are convenient if you are on the road and get hungry and you need a quick meal. The service at a fast food restaurant is quicker than making a homemade meal at the house. Fast food can give people more time to do important tasks that they need to do. Fast food restaurants also have a separate play area where kids can run around and play on the slide or swing and just have fun while wait on the meal. Many people buy fast food because it’s cheaper. Some people think that fast foods are convenient because they dislike cooking. Younger people who are single eat more fast foods than older people and married couples just for the convenience of it. For years fast food was considered a poor people’s food. The drive-through was where people would go who could not afford the â€Å"good stuff†. The meals have since changed, introducing healthier meals and low calories.Show MoreRelatedFast Food Restaurants For The Obesity Epidemic1663 Words   |  7 P ages Fast-food restaurants are very cheap and convenient way to get a quick meal and also in quick, convenient areas. Whether someone is in a hurry or just need something to eat, pulling through a drive through is very simple and a way to get food almost instantly. Obesity is a significant issue in the United States and having America plastered in fast-food chain restaurants does not help the fact, but we can not put them to blame. People need education on nutrition to learn what they need to eat andRead MoreRelation Between Fast Food Restaurants and Obesity1195 Words   |  5 Pagesï » ¿Fast Food Restaurants and Obesity Introduction The combination of increasingly sedentary lifestyles, two-income families with children, busy single professionals and the proliferation of fast food restaurants in recent years has created a perfect storm of obesity in the United States as well as a number of other countries. Further exacerbating the problem is the lack of nutrition and high levels of fat content in many fast food restaurant products, making their consumption a high-risk activityRead MoreFast Food Restaurants Are Being Blamed For Obesity Essay1133 Words   |  5 Pagesbibliography for research on how fast food restaurants are being blamed for obesity. I am researching the significance of fast food chains being blamed for obesity rates rising, when we, in fact should be looking at the individual responsible. Rice, S., McAllister, E. J., and Dhurandhar, N. V. Fast Food: Friendly? International Journal of Obesity (2007): pp. 884-86. Academic Search Premier. Web. In this article published by the International Journal of Obesity, S. Rice, Department ofRead MoreObesity in America: Fast Food Restaurants are NOT the Problem918 Words   |  4 PagesWith the continued growth of fast food restaurants, low priced food, and fast friendly service, these restaurants have become very appealing to the average consumer. With this increase in popularity, there has come many problems for these companies associated with the fast food industry. These stores are being blamed for the rise of obesity and other health issues in America; leading to many wanting a ban or probation on these fast food restaurants. The Government has stepped in on this issue andRead MoreFast Food Restaurant s Cause Obesity1259 Words   |  6 PagesToday two thirds of adults and nearly one third of children struggle with overweight and obesity. Most people in today’s society think that fast food restaurant s cause obesity, but they most likely do not. It is a person’s c hoice of what they put in their body. Even though thousands of fast food restaurants have to follow certain pricing standards, their cheap food is usually unhealthy and their expensive food is usually healthy, the amount of individual responsibility depends on whether you keepRead MoreEssay on Fast Food Restaurants Aren’t to Blame for Obesity598 Words   |  3 Pages In the 21st century, obesity has become a big problem. In fact, 35.7% of adults, 16.9% of kids, and 30.4% of preschoolers are obese in the U.S.! These numbers are still rising and many people are blaming fast food restaurants. Fast food restaurants aren’t the ones to be blamed for obesity; people are. One reason people eat fast food so much is because our bodies crave sugar, fat, and salt. Food companies use sugar, fat, and salt to get people to buy their products. Eating these unhealthyRead MoreFast Food Restaurants, Childhood Obesity, and Healthy Eating Habits3327 Words   |  13 Pages Fast Food Restaurants, Childhood Obesity, and Healthy Eating Habits Today, fast food restaurants are often blamed for childhood obesity. This is however a simplistic point of view, there are a number of factors that contribute to the current epidemic of childhood obesity. When all is said and done, the responsibly of teaching children healthy eating habits and encouraging regular exercise to mitigate this problem lies with parents. It is estimated that as many as one in five Americans is obeseRead MoreAre We Taking It Too Far by Blaming Fast Food Restaurant for Obesity?1285 Words   |  6 PagesAre we taking it too far by blaming fast food restaurant for obesity? Although throughout the years many people have claimed that obesity is a genetic disorder for the most part; results of recent studies strongly indicate that lifestyles rather than genetics are what are causing an obese society, because people choose to not exercise, not watch their diet, and eat fast food. For the past few decades, food companies had aimed their marketing at single meals, pushing to inflate portion sizes. ThatRead MoreObesity Fast Food Nation Essay661 Words   |  3 PagesFast Food Nation Obesity has grown into a rampant issue all over the United States, over the past few decades. Fast foods also have increased their outlets in the nation, in turn, depicting a success in the business venture. 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Block Diagram Of A Communication System Computer Science Essay Free Essays

string(189) " enabling downloading application plans by public package platform engineering, multimode wireless entree platform engineering, and high quality media coding engineering over nomadic webs\." The room access to the presents wireless communicating systems was opened by Guglielmo Marconi when he transmitted the three-dot Morse codification for alphabet ‘ S ‘ by the usage of electromagnetic moving ridges over a 3-KM nexus in 1895. This laid the foundation of modern communicating systems runing from broadcast medium, satellite transmittal and wireless finally come oning to presents cell phones. It would n’t be incorrect to state that wireless communicating has so revolutionized our present society A sudden addition has been observed in the enlargement of wireless systems during the last two decennaries. We will write a custom essay sample on Block Diagram Of A Communication System Computer Science Essay or any similar topic only for you Order Now We have seen great development in Wireless communicating systems from 1G narrowband parallel systems in the 1980s to the 2G narrowband digital systems in the 1990s. Now the bing 3G broadband multimedia systems are being deployed. In the interim, research and advancement in the future-generation wideband multimedia wireless systems is smartly being pursued worldwide. To link nomadic users to the populace switched web the United States introduced foremost radiotelephone service by the terminal of the fortiess. Improved Mobile Telephone Service was launched by Bell Systems in 1960s due to which tonss of betterments like direct dialing and addition in bandwidth took topographic point. IMTS formed the bases of the first parallel cellular systems. The term cellular was used due to the fact that coverage countries were disconnected cells, they had a low power sender and receiving system. BLOCK DIAGRAM OF A COMMUNICATION SYSTEM Figure 1. Block diagram of a general communicating system. ANALOG vs. DIGITAL COMMUNICATION SYSTEMS Definition of Digital A method of hive awaying, processing and conveying information through the usage of distinguishable electronic or optical pulsations that represent the binary figures 0 and 1. Advantages of Digital low-cost dependable Easy to pull strings Flexible Compatible with other digital systems The information in digital signifier can merely be transmitted without any debasement through a noisy channel Incorporated webs Disadvantages of Digital Sampling Mistake As compared to analogue, larger bandwidth is required in digital communications for the transmittal of the same information. Synchronism in the communications system is required to acknowledge the digital signals, but this is non the instance with linear systems. Definition of Analogue Analogue is a transmittal criterion that uses electrical urges to emulate the audio wave form of sound. When you use a phone, the fluctuations in your voice are transformed by a mike into similar fluctuations in an electrical signal and carried down the line to the exchange. Advantages of Analogue less bandwidth is required More Accurate Disadvantages of Analogue Signal loss and deformation can be seen due to the effects of random noise which is impossible to retrieve GENERATIONS OF CELLULAR SYSTEMS The construct of cellular telephone was introduced in AMPS, abruptly for Advanced Mobile Phone Systems. AMPS divided the entire country into little parts called cells and this was from where the construct of cellular telephone started. Cellular Systems had many advantages such as they increased quality, capacity, dependability and handiness of nomadic telephone web. The coevalss of cellular systems are described below. FIRST GENERATION CELLULAR SYSTEMS First coevals cellular telephone systems were introduced in 1980 ‘s. They were based on Analog Frequency Modulation technique. Each channel was assigned a exclusive frequence. First coevals cellular systems offered merely wireless voice services based on parallel engineering. Digital signals were merely used for control information such as dialing a figure etc. These systems were no able to get by with the increasing demands of users besides they had really less capacity and provided hapless voice quality. Some first coevalss systems are Advanced Mobile Telephone System, AMPS NAMPS, AMPS Entire Access Cellular System ( TACS ) Nordic Mobile Telephone System ( NMT-900 ) Second GENERATION CELLULAR SYSTEMS Second Generation Cellular Systems provided larger capacity and provided much better services to users compared to first coevals systems. They were based upon Digital Modulation technique which led to great sweetening in web ‘s capacity. Second Generation Systems used multiple entree techniques such as TDMA and FDMA. The biggest draw back of Second Generation Systems was that its different systems were non compatible with each other. Therefore rolling between different systems was non possible. Some of Second Generation Systems are North American Digital Cellular, NADC Global System for Mobile Communication, GSM Pacific Digital Cellular, PDC CDMAONE, IS-95 CDMA In order to get the better of Second Generation compatibility job with increased information rates of modern cyberspace applications, 2.5 Coevals criterions were developed. The best thing about them was that they allowed already bing Second Generation systems to be upgraded so that they can be used for higher information rate transmittal. 2.5 Generation brought a new revolution in cellular telephone by back uping services like high velocity cyberspace and location based nomadic services. Some of 2.5 Generation Mobile Systems are General Packet Radio Service, GPRS Enhanced Data Rate for GSM Evolution, EDGE Third GENERTAION CELLULAR SYSTEMS Designed to supply high quality and high capacity in informations communicating, Third Generation Systems require sophisticated spreading and transition techniques. Third Generation Systems are aimed to supply voice quality comparable to set down line telephone and besides to back up high informations rate. These systems are compatible with circuit switched every bit good as package switched informations services. They are besides compatible with the bing webs and usage wireless spectrum much more expeditiously than earlier. Some Third Generation Systems are Wideband CDMA, WCDMA Universal Mobile Telephone System, UMTS CDMA 2000 BEYOND 3G The extremely developed version of the 3G nomadic communicating are the 4G nomadic communicating services. It is estimated that 4G nomadic communicating services will give addition in capacity, informations transmittal with high velocity, broadband, HQ colour picture images for users, in writing life games in 3D, sound services in 5.1 channels. For the system and architecture of 4G nomadic communicating many researches are done. Developments are made in the terminal protocol engineering for high velocity package services, larger capacity, enabling downloading application plans by public package platform engineering, multimode wireless entree platform engineering, and high quality media coding engineering over nomadic webs. You read "Block Diagram Of A Communication System Computer Science Essay" in category "Essay examples" Why 4G? Servicess like wireless cyberspace and teleconference can be carried by 4G. Global mobility and service portability. Wider bandwidths. Increased spot rates. Less expensive. Mobile webs can easy be scaled. Chapter # 02 Multiplexing is a procedure in which a individual bearer is used to convey several different signals. These several signals are transmitted all together by uniting them and organizing one signal that will efficaciously travel through the bearer bandwidth. When one transmittal is done and the signal reaches the finish point, the incorporate signal re-assembles into its existent signifier and is so received. Multiplexing is one of the most used techniques today in about every communicating system. Because of the technological progress multiplexing, we have seen major addition in efficiency of a broad scope of telephone services and on-line applications. Multiplexing has become an effectual technique that assists in everything from video conferences and web conferences up to bulk informations transmittals and even doing a simple Point-to-Point phone call. FDMA: FDMA is the most usual technique used for multiple accessing. FDMA stands for frequence division multiple entree. It is clear from its name that in this technique the frequence is divided among the users as the available spectrum is shared among them in the frequence sphere. The message signals are transmitted onto bearers for different users utilizing peculiar RF frequences. Within FDMA structural design the Single Channel Per Carrier ( SPSC ) is the simplest method where each channel is provided with a separate bearer. This scheme finds its kernel in the fact that the channels are assigned on the footing of demand. Within a cell all the channels are available to all users all the clip, and the channels are assigned as soons as a message signal is received or a petition is made. Guard sets are used to cut down the opportunities of intervention from next channels. These guard sets are present between the sets allocated for assorted channels. In the execution of the first parallel cellular systems, FDMA is the multiplexing technique that was used. TDMA: Time division multiple entree techniques allots different clip intervals to different users for the transmittal of signals and storage of the information is carried out in one frequence channel non like FDMA which uses one frequence per channel. Users are allowed to utilize the same frequence but the clip slots are divided. In TDMA techniques the available spectrum is divided into little frequence sets as in FDMA, which are farther sub-divided into assorted clip slots. The user can entree the frequence channel merely for clip slot allotted to him. User can utilize sporadically the peculiar continuance of clip. In TDMA systems, guard sets are required between both frequence channels and clip slots. SDMA: SDMA stands for Space-Division Multiple Access. It is a MIMO ( Multiple-Input, Multiple-Output, a multiple aerial conventional architecture ) based radio communicating web architecture. It enables entree to a communicating channel by the procedure of placing the user location and set uping a one-on-one function between the web bandwidth allocation and the acknowledged spacial location that is why it ‘s largely suited for nomadic ad-hoc webs. For bulk of the well known nomadic communicating architectures such as CDMA, TDMA and FDMA, SDMA architecture can be configured and implemented CDMA: CDMA stands for Code division multiple entree. CDMA systems are based on the spread spectrum technique. In which transmittals by all the users are carried out at the same time while operating at the same frequence and utilizing the full spectrum bandwidth. For the designation and extraction of needed transmittal, each user is allotted with a alone codification which can non fit with any other user. This issue of designation is due to the fact that all the users transmit at the same time. To guarantee this privateness, pseudo-random noise codifications or PN codifications are used. These codifications are really the extraneous codifications and its advantage is that it reduces the opportunities of transverse correlativity among themselves. By utilizing this PN codification assigned to the specific user, transition of the message signal from an single user is done. Then we have the CDMA frequence channel through which all the modulated signals from different users are transmitted. At the receiving system ‘s terminal, the coveted signal is so recovered by de-spreading the signal with a reproduction of the PN codification for the specific user. The signals whose PN codifications are non matched with the coveted signal and are assigned to different users are non de-spread and as a consequence are regarded as noise by the receiving system. CDMA differs from both TDMA and FDMA in a manner that it allows users to convey the signal at the same clip and operate at the same nominal frequence so it requires less synchronization whereas in TDMA and FDMA frequence and clip direction is really critical so more dynamic synchronism is required. One more advantage of CDMA is that complete system ‘s spectrum is used by signals and hence no guard sets are required to protect against next channel intervention. Intro to Spread Spectrum Communications Following are the major elements that can clearly depict the Spread Spectrum communications: By spread spectrum, bandwidth far in surplus is available than that is necessary to direct the information. Due to this characteristic the transmittal can be protected against intervention and jamming at the same clip supplying multiple entree capableness. An independent codification known as the Pseudo random codification is used for signal spreading across the bandwidth. The distinguishable nature of this codification separates dispersed spectrum communications from typical transition techniques in which transition ever spread ‘s the spectrum slightly. For the recovery of the original signal the receiving system is synchronized to the deterministic imposter random codification. Users can convey the signal at the same clip and operate at the same nominal frequence by utilizing independent codification and synchronal response. In order to protect the signal from intervention a pseudo-random codification is used. It appears to be random to anyone who does non hold its pre-defined cognition but in world is deterministic, it is because of this fact that receiving system is able to retrace the codification needed for the recovery of the needed informations signal. This codification used for synchronal sensing is besides called Pseudo noise sequence. Types of Spread Spectrum Communications Spreading of bandwidth of the signal can be achieved by three ways: Frequency skiping The signal is shuffled between different Centre frequences within the full bandwidth available to the hopper pseudo-randomly, and the receiving system used already knows where to look for the signal at a given clip. Time skiping The signal is transmitted in short explosions pseudo-randomly, and the receiving system knows when a explosion is expected. Direct sequence Very high frequence is used to code the digital information. The codification is pseudo-randomly generated. The same codification is generated at the receiver terminal, and in order to pull out the original information this codification is multiplied to the received information watercourse. Beginning Cryptography AND DIGITAL MODULATION 3.0 Introduction Digital Modulation is performed in order to stand for digital informations in a format that is compatible with our communicating channel. Why Digital Modulation? Digital transition strategies have greater capacity to convey big sums of information than parallel transition strategies. 3.1 DIGITAL DATA, DIGIITAL SIGNAL Digital signal is binary informations encoded into signal elements. Different encoding strategies for encoding digital informations into digital signal are: 3.1.1 Non Return to Zero ( NRZ ) In NRZ there are two different electromotive force degrees for 0 and 1. There is no passage in the center of the spot. The absence of signal denotes 0 and a positive electromotive force degree denotes 1. The major drawback of NRZ strategy is that it adds a dc constituent to the signal. 3.1.2 Multilevel Binary ( AMI ) In this encoding strategy there are more than two degrees. No signal represents 0 and 1 is represented by some positive and negative There is no dc constituent in this strategy and besides there is no loss of synchronism for back-to-back 1 ‘s. 3.1.3 Manchester Coding There is passage in center of each spot, which acts as a clock every bit good as informations. The low to high passage represents 1 and high to low represents 0. 3.1.4 Differential Manchester In this scheme passage at the center of the spot represents merely timing while passage at start represents 0 and no passage at start represents 1. 3.2 ANALOG DATA, DIGITAL SIGNAL Analog informations is foremost converted into digital informations by utilizing parallel to digital convertors. These convertors use different techniques to finish their undertaking, some of them are: 3.2.1 Pulse Code Modulation If a signal is sampled at regular intervals at a rate higher than twice the highest signal frequence, the samples contain all the information of the original signal. Each sample is assigned a digital value. Although its quality is comparable to that of parallel transmittal but still in this procedure some information is lost and the original signal can ne’er be recovered. Delta Modulation Analog input is approximated by a stairway map. Function moves up or down at each sample interval by one degree ( vitamin D ) . Delta transition is easier than PCM in execution, but it exhibits worse signal to resound ratio for the same information rate. But it is good for informations compaction. DIGITAL DATA, ANALOG SIGNAL Different digital transition techniques are: Amplitude Shift Keying ( ASK ) A transition technique in which digital information is represented as fluctuations in the amplitude of a bearer moving ridge is called Amplitude-shift keying ( ASK ) . One binary figure is represented by presence of bearer, at changeless amplitude and the other binary figure represented by absence of bearer. 3.3.2 Frequency Shift Keying ( FSK ) In frequence displacement identifying different frequences are used to stand for incoming digital information. Say in instance of Binary Frequency Shift Keying f1 is used to stand for 0 while f2 is used to stand for 1. In MFSK more than two frequences are used and therefore bandwidth is more expeditiously utilised. 3.3.3 Phase Shift Keying ( PSK ) A digital transition technique in which information is transmitted by modulating and altering the stage of the mention signal is called Phase-shift keying ( PSK ) . In instance of PSK, a finite figure of stages are used. A alone form of binary spots is assigned to each of these stages. By and large, each stage encodes an equal figure of spots. The symbol is formed by each form of spots that is represented by the peculiar stage. The bandwidth of ASK and PSK are specified as: Whereas the bandwidth of FSK is given as: Where, Roentgen is the spot rate DF = f2 – fc = fc – f1 Chapter # 04 CHANNEL Cryptography 4.0 Introduction Why Channel Cryptography? In modern digital communicating systems information is represented in spot watercourses, which are so modulated to analog wave forms before being transmitted onto a channel. At receiving system this parallel information is demodulated into spot streams, but because of the presence of intervention and noise in the communicating channel this spot watercourse may be corrupted. So to minimise happening of spots in mistake and protect digital information from channel noise and intervention channel cryptography is used. How Channel Coding is performed? Additional redundant spots are added to the message informations watercourse to execute channel cryptography, these excess spots assist in mistake sensing and rectification at the receiving system ‘s terminal. Channel Coding at the cost of? Channel Coding is performed at the cost of bandwidth enlargement and information rate decrease. 4.1 TYPES OF CHANNEL CODING TECHNIQUES There are two chief types of channel coding techniques, Block Codes Convolutional Codes. Block Codes accepts thousand figure of information spots and bring forth a block of n figure of encoded spots, and therefore are normally known as ( n.k ) block codifications. Some common illustrations of block codifications are Overacting Codes and Reed Solomon Codes. Convolutional Coding is frontward error rectification technique that is presently most widely used in modern communicating systems, this peculiar technique is used for real-time mistake rectification. Unlike block codifications which append excess spots at the terminal of original message signal, Convolutional coding organize a new codeword utilizing original informations watercourse. The encoded spots are non entirely dependent on K current input spots but at the same clip on case in point input spots. 4.2 CONVOLUTIONAL CODES In this undertaking Convolutional Coding is implemented. Convolutional Codes are farther classified as 1. Trellis Coded Modulation ( TCM ) 2.Turbo Codes. Trellis Coded Modulation ( TCM ) is non recursive, non systematic and does non necessitate an interleaver. Turbo Codes on the other manus are recursive, systematic, parallel structured and they besides require interleaver. In Wideband CDMA systems TCM is used for all channels while Turbo Codes may be used for DCH and FACH channels. Turbo Codes are sometimes classified as separate subdivision of Channel Codes so from here onwards word Convolutional Code will merely be used for TCM. Types of Transmission Channels Convolutional Cryptography 1/2 BCH PCH DCH, FACH 1/2, 1/3 Turbo Coding 1/3 4.3 CONVOLUTIONAL CODE REPRESENTATIONS 4.3.1 Polynomial Representation No. of input information spots = K No. of encoded spots = Ns No. of phases ( Constraint Length ) = K Code Rate = k/n Encoded CodeWord = U The undermentioned illustration shows how Convolutional Codes are represented. Let g1 ( x ) and g2 ( ten ) be encoder multinomials, where g1 ( x ) = 1 + x + x2 g2 ( x ) = 1 + x2 Let input message spot stream be 101, hence input message spot stream multinomial will be, m ( x ) = 1 + x2 The encoded codeword ‘U ‘ will be combination of merchandise of g1 ( x ) with m ( x ) and g2 ( x ) with m ( x ) , m ( x ) x g1 ( x ) = 1 + 1.x + 0.x2 + 1.x3 + 1.x4 m ( x ) x g2 ( x ) = 1 + 0.x + 0.x2 + 0.x3 + 1.x4 Therefore the codeword ‘U ‘ , becomes U = ( 1,1 ) + ( 1,0 ) .x + ( 0,0 ) .x2 + ( 1,0 ) .x3 + ( 1,1 ) .x4 U = 1 1 1 0 0 0 1 0 1 1 4.3.2 State Transition Diagram Convolutional Coding can be represented utilizing State Transition Diagram. Following are State Transition Diagram and State Transition Again for the same input spot stream 10100, the codeword U = 11 10 00 10 11. In the input message last two ’00 ‘ spots are tail spots. 4.3.2 Block Diagram Representation The undermentioned diagram shows block diagram representation of Convolutional Coding with Code Rate = 1/2 Constraint Length ( No. of Stages ) = 3 The undermentioned illustration illustrates the procedure of Convolutional Coding utilizing block diagram representation for input spot stream 101. So the concluding codeword becomes, U = 11 10 00 10 11 4.3.2 Trellis Diagram Representation For input spot stream 101, the following diagram shows how Convolutional Coding is performed utilizing Trellis Diagram Chapter # 05 PULSE SHAPING TECHNIQUES 3.0 Introduction Why Pulse Determining? It is done in order to cut down Inter Symbol Interference normally known as ISI. How Pulse Shaping is performed? In order to accomplish zero-ISI the overall system response must be equal to Nyquist frequence response. 5.1 RAISED COSINE FILTER Inter Symbol Interference significantly degrades the informations sensor ability to distinguish between a current symbol from diffused energy of next symbol. This leads to the sensing of mistake and increases BER. So in order to provide ISI, a real-time realisation of Nyquist filter is applied in modern communicating systems. Raised cosine filter is one of the realisation of Nyquist filter. where R = ‘roll-off factor ‘ = 1 ? R ? 0 and T = ‘symbol period ‘ = 1/R Roll-off factor determines the filter bandwidth and represents a tradeoff between the acuteness of the passage set of the filter and impulse response pealing magnitude of the filter. A Nyquist filter has following belongingss: Time response finally goes to zero in a clip period precisely equal to the symbol spacing. By trying the symbol sequence at a given symbol clip point, present symbol is non affected by the energy distributing from the next symbols. The impulse response and the frequence response of the RC filter is Time response of the RC filter goes to zero with a period that precisely equal to the symbol spacing. As the response equals zero at all symbol times except for the coveted one none of the next symbols interfere with each other. 5.2 ROOT RAISED COSINE FILTER RC filter is divided into a root raised cosine ( RRC ) filter brace, with one at the transmitter terminal, which performs the pulsation defining in order to restrain the modulated signal bandwidth, and the other at the receiver terminal, that performs matched sensing for optimising the SNR of a known signal in AWGN presence. The Root Raised Cosine filter is so named because its transportation map precisely is the square root of the transportation map of the Raised Cosine filter. Where R = roll off factor and T is symbol period. The RRC filter bandwidth is equal to the root mean square ( RMS ) amplitude 2R. The impulse response and the frequence response of the RRC filter is Both RC and RRC have similar pulsation forms, but the RRC pulsation makes somewhat faster passages, therefore the spectrum of RRC pulsation decays more quickly every bit compared to the RC pulsation. Another of import difference between both pulsations is that the RRC pulsation does non hold zero Inter Symbol Interference. Because of the fact that RRC filter is used at sender and receiver both, the merchandise of these transportation maps is a raised cosine, which will ensue in zero ISI end product. 5.3 ROLL OFF FACTOR The roll-off factor, R, is a step of the extra bandwidth of the filter, i.e. the bandwidth occupied beyond the Nyquist bandwidth of 1/2T. Where a?† f is extra bandwidth and Rs is symbol rate. Chapter # 06 SPREAD SPECTRUM Spread spectrum is a type of transition where the information is spread across the full frequence spectrum. This procedure of distributing the information across the full spectrum helps signal against noise and intervention. These techniques are largely employed in cell phones and besides with wireless LAN ‘s. To measure up as a spread spectrum signal, two standards must be met The familial signal bandwidth must be in surplus of the information bandwidth. Some map other than the informations being transmitted is used to set up the bandwidth of the attendant transmittal. Why Spread Spectrum? Due to its sole and curious belongingss spread spectrum is preferred over other transition strategies. Some of these belongingss are characterized as advantages and disadvantages of a basic spread spectrum system below. Advantages †¢ It reduces the effects of multipath intervention and at times removes them wholly. †¢ Frequency set is shared at the same time with other users. †¢ Pseudo random codifications guarantee protection of transmittal and privateness. †¢ As the signal is spread over an full spectrum it has a low power spectral denseness. Disadvantages †¢ Due to distributing operation it consumes more bandwidth. †¢ It is at times hard to implement. Types of Spread Spectrum Techniques Most normally used techniques in a spread spectrum systems are Direct Sequence Spread Spectrum Frequency Hoping Spread Spectrum Frequency Hoping Spread Spectrum A frequence skiping dispersed spectrum hops from one narrow set to another all within a wider set. In general the frequence hopper sender sends informations packages at one bearer frequence and so leaps to another bearer frequence before directing ore packages and continues the same modus operandi throughout the period of transmittal. The form that emerges seems to be random but is in fact periodic and easy traceable by pre configured sender and receiving system. These systems can be vulnerable to resound at a peculiar hop but normally are able to direct packages during the following hop. Direct Sequence Spread Spectrum Most widely used technique of spread spectrum is the Direct Sequence Spread Spectrum. A Direct Sequence Transmitter receives the entrance informations watercourse which is to be transmitted and so change over it into a symbol watercourse where the size of a symbol can be one or more spots. Using any of the transition strategies for digital systems such as Quadrature Amplitude Modulation ( QAM ) or Quadrature Phase Shift Keying ( QPSK ) this symbol watercourse is multiplied to a noise like sequence known as imposter random sequence. It is besides know as a bit sequence. As a consequence of this generation the bandwidth of the transmittal is significantly increased. Figure 3. Direct Sequence Spread Spectrum System Figure 3. shows the working of a basic Direct Sequence Spread Spectrum system. For lucidity intents, one channel is shown working in one way merely. Transmission For each channel a distinguishable and different Pseudo random codification is generated. In order to distribute the informations the information watercourse is multiplied with the antecedently generated Pseudo random codification. The signal obtained as a consequence of this generation is so modulated onto a bearer. This modulated bearer wave form is so amplified before broadcast medium. Reception The bearer moving ridge is amplified every bit shortly as it is received by the receiving system. The signal received is so multiplied with a locally generated bearer which gives the spreaded signal. Again a Pseudo random codification is generated on the footing of the signal expected. The procedure of correlativity is carried out on the standard signal and the generated codification which gives the original message signal. Pseudo-Random Noise The spread spectrum systems are constructed really similar to other conventional systems. The difference being the add-on of pseudo random generators both at the sender and the receiving system which generate the Pseudo noise sequences required for the functionality of Direct Sequence spread spectrum. These pseudo random noise sequences are used for distributing the signal at the transmitter side and dispreading at the receiver side. A pseudo noise sequence is made up of a figure of symbols which are called french friess. It is imperative that a good codification is selected for its type and length straight affects the system capableness. A alone codification is generated for each channel. All the transmittals for a peculiar user are so added together. At the receiving system each user generates its ain matching codification in order to retrieve the original signals. In order to measure up as a imposter random codification and proper functionality a codification must hold the undermentioned belongingss. The imposter random codification must be deterministic so that the receiving system can bring forth the exact codification as used by the sender It should be random for any hearer who does non hold the cognition of the codification being used so that it appears as noise to any interferer or eavesdropper. Two codifications must be indistinguishable and have no or really little relevancy to each other. The codification should non reiterate shortly there must be a long clip before that happens. Maximal length sequences Maximal Length sequences can be generated by the aid of displacement registries with feedback applied on them. These sequences meet all the conditions for distributing sequences really purely. The cross correlativity between this sequence and noise is really low, which helps in observing signal out of noise in the receiving system. These sequences are really utile for encoding as they besides have a really low cross correlativity with each other. The entropy belongingss of maximum length sequences can be seen here. Gold Sequence In order to make two gold sequences, two maximal length sequences are to be combined. They have a really low auto-correlation which enables CDMA systems to convey asynchronously. Gold sequences are constructed by modulo-2 add-on of two maximum length sequences of same length chosen from braces of preferable m-sequences. Walsh Codes Walsh codifications have to be created from hadamard matrices. All generated Walsh codifications would be extraneous to each other. The basic hadamard matrix is shown below. These sequences provide low cross-correlation between each other. Second, the figure of 1 ‘s is same as the figure of 1 ‘s in each codeword. By looking at the matrix above, Walsh codes with different lengths can be generated with the aid of recursion. For a clear apprehension Walsh codes with length equal to 4 are illustrated below. = Spreading the Signal Signal spreading is achieved when the signal is multiplied bitwise with the imposter random sequence. Figure 4. Below gives an penetration into how two spots are multipliied to a pseudo random sequence holding a length of 8 and the its corresponding consequence on the frequence spectrum. Spreading procedure of two spots with the aid of an 8-chip PN sequence is shown on the left side and the consequence of this distributing on the signal ‘s frequence spectrum is shown on the right side of figure. 4 Figure 4. The rule of signal spreading De-spreading the Signal De-spreading of the signal is carried out by multiplying each spot of the signal to its correspond imposter random codification and the consequence is summed bitwise. Figure 5. describes the procedure of de-spreading when a imposter random signal of length 8 is used for transmittal and the de-spreaded signal is equal to the dispersed signal. De-spreading procedure of two spots with a PN sequence of 8-bit is shown on left side and the consequence of the de-spreading on the signal ‘s frequence spectrum is shown on the right. Figure 5. The rule of signal de-spreading Consequence of Spreading on Bandwidth Figure 1. As a consequence of distributing operation the signal ‘s frequence is spread over a wider bandwidth Spread spectrum transition is applied in tandem with some other digitial transition strategies such as QAM or QPSK. Consequence of Despreading on Bandwidth Figure 2. The despreading operation recovers the original signal. A spread spectrum transition is applied in coherency with a conventional demodulation process in order to retrieve the original signal. Multiple Access Capability The standard signal s1 is detected by the receiving system summed with the other signal s2. The signal s1 which is for user 1 is merely extracted at the receiving system for user 1 whereas the signal s2 appears to be as noise in comparing to the user 1 signal s1. This is shown in Figure 6. below For efficient recovery of the informations from user 1 it is must that the signal appearance as noise has adequately low energy in the information bandwidth of signal s1. Spreaded informations multi-users De-spreaded informations multi-users Spreaded informations multi-users De-spreaded informations multi-usersFigure 6. Multiple Access Capibility when user 1 recovers signal s1 Chapter # 07 DESIGN OF A CDMA BASED COMMUNICATION SYSTEM 7.1 THE Sender 7.1.1 Source Encoding In order to do incoming message compatible with the communicating system beginning cryptography is used. In this undertaking NRZ encoding strategy is used so that the incoming message signal becomes compatible with the walsh codifications which are besides in NRZ signifier. NRZ encoding provides a better use of the bandwidth, besides if we compare it with AMI strategy it is more efficient because in that receiving system has to separate between three different degrees and it requires more signal power. While the Manchester and differential Manchester strategies have transition rate twice or more than that of NRZ so therefore they require greater bandwidth. 7.1.2 Channel Encoding Channel encryption is performed so that spot mistakes can be reduced at the receiving system ; besides it protects the information from channel noise and intervention. In this undertaking we have used Convolutional Encoding technique and so hold tried to upgrade our system utilizing Low Density Parity Check ( LDPC ) . LDPC improves channel capacity as it approaches to Shannon capacity bound. Both Convolutional encoder and LDPC encoder organize a codeword based on the incoming message signal. We have used ? rate encoders that means that we have two input spots and the end product is traveling to be four spots. For Convolutional encoder inbuilt matlab treillage construction along with convenc bid has been used while in instance of LDPC fecldpc.enc bid is used to do LDPC object utilizing thin H matrix and so message is encoded utilizing LDPC object by encode bid. 7.1.3 Spreading The cardinal standard of spreading is transverse correlativity and car correlativity of message symbols. In instance of a CDMA based communicating system as there are many users that at the same time transmit informations so the system must hold good cross correlativity belongingss. This generates the demand of extraneous codifications so Walsh codifications are used. Walsh codifications have good cross correlativity belongingss. In this undertaking direct sequence spread spectrum ( DSSS ) technique has been employed to distribute the signal across the full bandwidth. 7.1.4 Digital Transition Transition is a technique that facilitates the message signal to be transmitted over the medium. In instance of digital transition, digital signal is modulated utilizing amplitude displacement keying, frequence displacement keying and stage displacement identifying etc. We have implemented Binary PSK, BPSK uses two symbols that have opposite stage to each other to modulate 0 and 1.Sampling frequence of 44 kilohertzs and a information rate of 2 kilohertz has been used in this system. In instance of LDPC modulate bid has been used to modulate the signal. 7.1.5 Pulse Determining The consequence of inter symbol intervention ( ISI ) is minimized by the aid of pulse determining procedure. In this undertaking Root Raised Cosine Filter has been used at the transmitter side to determine the pulsation so as to restrict the bandwidth of the modulated signal. By utilizing this technique bandwidth is limited but the signal spreads in so there must be a threshold in order to counter this job, this threshold is known as Nyquist bound. It is fundamentally a low base on balls filter with a axial rotation off factor 0.5 which has been used in this undertaking. 7.1.6 Symbol Packing In symbol wadding, a preparation sequence is appended at the start and terminal of the signal. Besides in add-on to this about 1000 nothings are inserted at the terminal and start of the signal. These are added so that even if the receiving system fails to have initial spots these spots are extra nothings and non the message signal. 7.2 THE CHANNEL In a communicating system channel could be wired or wireless. Different channels have different features. When of all time we talk about a channel we talk about noise, it is fundamentally the unwanted electrical signal that confines the receiving system ability to take right determinations. Channel noise degrades the end product really rapidly. Small channel does n’t do much difference to the end product signal but big channel noise well degrades the signal. In instance of little channel noise the lone noise that is present in the system is quantization noise. Another of import factor in a communicating system is Inter symbol intervention ( ISI ) . When the channel bandwidth is non much greater than signal bandwidth the spreading of the signal causes ISI. Normally, the radio channel is modeled with AWGN channel. A thermic noise beginning is used to distribute an equal sum of noise power per unit bandwidth over all frequences that is the ground why a simple theoretical account for thermic noise presumes that its power spectral denseness Gn ( degree Fahrenheit ) is level for all frequences, as is denoted as: Gn ( degree Fahrenheit ) = N0/2 watts/hertz 7.3 THE Receiver 7.3.1 Synchronism In this system, it is assumed that the receiving system is on all the clip. Therefore whenever the sender will direct the message signal, there should be some manner through which the receiving system can find where its signal of involvement is. This can be done by correlating the preparation sequence with the standard signal. The portion where the maximal correlativity occurs would be the start of the signal and the 2nd upper limit in the correlativity would give the terminal of the message signal. 7.3.2 Matched Filtering The standard signal is passed through root raised cosine filter in order to execute matched filtering and down trying at the receiver terminal. Normally RC filter is divided into a root raised cosine ( RRC ) filter brace, with one at the transmitter terminal, which performs the pulsation defining in order to restrain the modulated signal bandwidth, and the other at the receiver terminal, that performs matched sensing for optimising SNR of a known signal in AWGN presence. 7.3.3 Demodulation The signal is demodulated by multiplying it by the bearer signal. The end product would be demodulated signal, but this demodulated signal would be sum of all the spreaded signals. 7.3.4 Despreading In order to pull out the single message signal of each user, the spreaded signal is so once more multiplied by the Walsh codification and is so integrated over a symbol clip. 7.3.5 Channel Decoding If the channel cryptography was non employed by the sender, so the despreaded messages would be the standard signals. In the channel coding instance, the signal will hold to be decoded by utilizing the viterbi decrypting map in matlab. 7.3.6 Source Decoding While executing beginning cryptography we had used NRZ encoding strategy, so now at the receiving system this encoded message is once more decoded back to its original signifier. How to cite Block Diagram Of A Communication System Computer Science Essay, Essay examples

Definition of Materiality Management

Question: Describe about the Materiality? Answer: Definition of Materiality: Any piece of information is considered to be material when its omission or its mis-statement would lead to the wrong decisions making by the users of the financial statements. The materiality of any transaction depends upon the nature and the amount of the item that has been judged in the circumstances when the same has been omitted or misstated. When the nature of the materiality is being considered, it becomes very difficult to consider the concept except when it relates with the qualitative characteristics of relevance and the faithful representation. Therefore, the materiality is something that decides whether the information will affect the decision making of the user of the financial information or not. (IFRS, 2015) Examples of materiality: For example the Cookie Jar reserves: Many of the companies try and build the excess reserves with the intention that the same could be used to inflate the income in the time of need. For example, the company increases its loan reserves when it recognizes the expenses in excess for 3 periods with the aim of reducing the stated reserve. The net effect of the transaction is that there is a cumulative approach that focusses on the misstatement amount at the end of the period that calculates the quantitative materiality based on that misstatement. Sometimes, he companies hold the current period amounts and the cumulative approaches yield an altogether different figure. For example the firm has a recurring late cut off error so that the current year sales includes the sake of the next year and the also the previous sales. All the figures must state the amount that is included for all the previous amounts and the same must be quantified so that the amounts are correctly reported. (www3.nd.edu, 2015) Articulation of the financial statements: There are two elements that have a connection in the way in which the assets, liabilities and the net assets are changed and are affected by the change in the elements of another type. At any period of given period, the cumulative result of the transactions is an increase in the asset that cannot occur without the corresponding decrease in either another asset or a decrease in the liability. These are the relations that are sometimes called articulation. It results in the interconnection of the financial type. The assets, liabilities of an organization describes the amounts of the resources that an organization has and the claims that the organizations has as against it. All of these elements affect the transactions and the other such events that affects the entity during the regular course of the activities. When it comes to a business enterprise, the second type of the element includes the revenues, expenses, gains, losses and the investment by the owners and the distribution of the same to the owners. When it comes to not for profit organization, it includes revenues, expenses, gains and losses. (FASB, 2015) References: /www3.nd.edu, (2015). Quantitative Materiality Perspectives and Auditors Disposition of Detected Misstatements. [online] Available at: https://www3.nd.edu/~carecob/Workshops/03-04%20Workshops/Nelson.pdf [Accessed 23 Mar. 2015]. www.fasb.org, (2015). Statement of Financial Accounting Concepts No. 6. [online] Available at: https://www.fasb.org/resources/ccurl/792/293/CON6.pdf [Accessed 23 Mar. 2015]. www.ifrs.org, (2015). Conceptual Framework Qualitative Characteristics 4: Definitions of understandability and materiality. [online] Available at: https://www.ifrs.org/Meetings/MeetingDocs/IASB/Archive/Conceptual-Framework/Previous%20Work/CF-0507b07b.pdf [Accessed 23 Mar. 2015].