Communication and networking

                     Communication and networking

Definition of Networking:-
           A computer network is a set of computers or devices that are connected with each other to carry on data and share information. In computing, it is called a network as a way to interconnect two or more devices to each other using cables, signals, waves or other methods with the ultimate goal of transmitting data, share information, resources and services.

Purpose of networking:

                   The purpose of a network is, generally, to facilitate and expedite communications between two or more instances on the same physical space or connected remotely. Such systems also allow cost savings and time.  

                     The most known type of network is the Intranet, which is a private network that uses Internet as a basic architecture in order to connect various devices. Internet, however, is a technology that connects devices throughout the world, and that is why it is called “network of networks.”

Classifications of Networks:
                           The networks are classified by range (personal, local, campus, metropolitan or wide area), as well as by method of connection (cable, fiber optics, radio, infrared, wireless, etc..) or by functional relationship (client – server or peer‐to‐peer). Also in the topology field there is a classification to be aware of (bus, star, ring, mesh, tree etc.) and directional (simplex, half duplex or full duplex).

Use of a network:
                      The use of a network in an office, for example, in which all employees have the same access to resources such as programs and applications or devices like a printer or scanner. Moreover, configuring a large‐scale network facilitates communication among different geographic locations, so a company with multiple branches in the world can keep in communication with its members in a simple and quick. Finally, a network can be used as a home to share files or maximize the available space.

Analog Network Signaling:

An analog signal is best compared to a wave. It has similar properties to an ocean wave, and can be
described using three specific characteristics: amplitude, frequency, and wavelength.
To use the ocean wave analogy an analog signal's amplitude is like the height of a wave rolling in onto  the beach. The frequency of an analog signal can be compared to how fast the waves roll in. Wavelength can be compared to the distance between one wave and the next wave. Wavelength is measured as the distance between the peak of one wave and the next.

Advantages and Disadvantages of Analog Signals
Analog signals are variable and can convey more subtly than a digital signal. For example the human
voice is analog, and has more tone than a digital representation of the same voice. However, analog
signals are very vulnerable to interference from outside forces and other waves which can cancel them out.

Digital Network Signaling:
A digital signal is made up of on/off states.  Unlike the smooth curve of an analog wave, the digital signal cuts on and off.  This happens to perfectly fit the type of communication inside a computer, which is made up of on/off states as well.

Advantages and Disadvantages of Digital Signals:

Digital signals are much more reliable than analog signals because they are less vulnerable to interference and errors. However, digital equipment costs more and is much more complex.

Modulation (AM, FM, PM)
In telecommunications, modulation is the process of conveying a message signal, for example a digital bit stream or an analog audio signal, inside another signal that can be physically transmitted. Modulation of a sine waveform is used to transform a base band message signal into a pass band signal, for example low￾frequency audio signal into a radio-frequency signal (RF signal). In radio communications, cable TV
systems or the public switched telephone network for instance, electrical signals can only be transferred over a limited pass band frequency spectrum, with specific (non-zero) lower and upper cutoff frequencies. Modulating a sine-wave carrier makes it possible to keep the frequency content of the transferred signal as close as possible to the center frequency (typically the carrier frequency) of the pass band.
             A device that performs modulation is known as a modulator and a device that performs the inverse operation of modulation is known as a demodulate (sometimes detector or domed). A device that can do both operations is a modem (modulator–demodulate).

Amplitude Modulation (AM)
                 Amplitude modulation (AM) is a method of impressing data onto an alternating-current(AC) carrier waveform.The highest frequency of the modulating data is normally less than 10 percent of the carrier frequency.The instantaneous amplitude(overall signal power) varies depending on the instantaneous amplitude of the modulating data. In AM, the carrier itself does not fluctuate in amplitude. Instead, the modulating data appears in the form of signal components at frequencies slightly higher and lower than that of the carrier. These components are called side bands. The lower side band (L S B) appears at frequencies below the carrier frequency; the upper side band (USB) appears at frequencies above the carrier frequency. The  LS B and USB are essentially "mirror images" of each other in a graph of signal amplitude versus frequency, as shown in the illustration. The side band power accounts for the variations in the overall amplitude of the signal. When a carrier is amplitude-modulated with a pure sine wave, up to 1/3 (33 percent) of the overall signal power is contained in the side bands. The other 2/3 of the signal power is contained in the carrier, which does not contribute to the transfer of data. With a complex modulating signal such as voice, video, or music, the side bands generally contain 20 to 25 percent of the overall signal power; thus the carrier consume 75 to 80 percent of the power. This makes AM an inefficient mode. If an attempt is made to increase the modulating data input amplitude beyond these limits, the signal will become distorted, and will occupy a much greater bandwidth than it should. This is called over modulation, and can result in interference to signals on nearby frequencies.

Frequency Modulation (FM)
Frequency modulation (FM) is a method of impressing data onto an alternating-current (AC) wave by
varying the instantaneous (immediate) frequency of the wave. This scheme can be used with analog or digital data.

Analog FM
In analog FM, the frequency of the AC signal wave, also called the carrier, varies in a continuous manner. Thus, there are infinitely many possible carrier frequencies. In narrow band FM, commonly used in two-way wireless communications, the instantaneous carrier frequency varies by up to 5 kilohertz (kHz, where 1 kHz = 1000 hertz or alternating cycles per second) above and below the frequency of the carrier with no modulation. In wide band FM, used in wireless broadcasting, the instantaneous frequency varies by up to several megahertz (MHz, where 1 MHz = 1,000,000 Hz). When the instantaneous input wave has positive polarity, the carrier frequency shifts in one direction; when the instantaneous input wave has negative polarity, the carrier frequency shifts in the opposite direction. At every instant in time, the extent of carrier-frequency shift (the deviation) is directly proportional to the extent to which the signal amplitude is positive or negative.

Digital FM
In digital FM, the carrier frequency shifts abruptly, rather than varying continuously. The number of
possible carrier frequency states is usually a power of 2. If there are only two possible frequency states, the mode is called frequency-shift keying (F S K). In more complex modes, there can be four, eight, or more different frequency states. Each specific carrier frequency represents a specific digital input data state.

Phase Modulation (PM):
Phase modulation (PM) is a method of impressing data onto an alternating-current (AC) waveform by varying the instantaneous phase of the wave. This scheme can be used with analog or digital data.

Analog PM, The phase of the AC signal wave, also called the carrier, varies in a continuous manner.
Thus, there are infinitely many possible carrier phase states. When the instantaneous data input waveform has positive polarity, the carrier phase shifts in one direction; when the instantaneous data input waveform has negative polarity, the carrier phase shifts in the opposite direction. At every instant in time, the extent of carrier-phase shift(the phase angle) is directly proportional to the extent to which the signal amplitude is positive or negative.

Digital PM
In digital PM, the carrier phase shifts abruptly, rather than continuously back and forth. The number of possible carrier phase states is usually a power off. If there are only two possible phase states, the mode is called bi phase modulation. In more complex modes, there can be four, eight, or more different phase states. Each phase angle (that is, each shift from one phase state to another)represents a specific digital input data state. Phase modulation is similar in practice to frequency modulation (FM). When the instantaneous phase of a carrier is varied, the instantaneous frequency changes as well. The converse also holds: When the instantaneous frequency is varied, the instantaneous phase changes. But PM and FM are not exactly equivalent, especially in analog applications. When an FM receiver is used to demodulate a PM signal, or when FM signal is intercepted by a receiver designed for PM, the audio is distorted. This is because the relationship between phase and frequency variations is not linear; that is, phase and frequency do not vary in direct proportion.

Computer Crime

                                  Computer Crime

Computer crime is the illegal use of a computer by an unauthorized individual, either for pleasure such as by a computer hacker or for profit as by a thief. Thus, it refers to any crime such as tampering, physical danger and unwanted disclosure of data that involves a computer and a computer network. It includes the computer that may have been used in the commission of a crime, or it may be the target.

        The increasing range of programmable electronic devices, such as PDF, iPad , iPhone, mobile devices, means that ' computer '. Crime can affect more than just personal compilers (PCs) to all these devices, which are particularly vulnerable to at track because of flexibility. They can be reprogrammed and are frequently connected with other devices. For example , a personal computer connected to the Internet without protection may be infected with malicious software within a minute.

Generally, computer crimes are committed for the following:-

  i.   Attempt illegally to access  information stored on a computer as information may have a sale              value, may be valuable to the owner or may be useful for further illegal activity such as fraud.
 ii.  Try to impede or alter the functioning of the computer itself as if computer can be controlled it           can be used to send spam, host illegal content, or conduct further at tracks.

              Many countries have passed cyber laws. Many other rules and regulations are emerged for the protection of the computer and its related resources. The recent surveys done by different agencies and organization show that the rate of computer crime has been increasing day by day. A range of technologies is available to home user and organizations to secure their computer from possible computer crimes.

Technological solutions
If correctly installed, the following can be help to block attacks:

1) firewalls:
                       These are hardware or software devices that block certain network traffic according to their security policy.

2) software solution:
                         These are used to identify and remove malware and to help manage spam email. Many must be paid for but free versions are also available. For example, Antivirus , Anti spyware software.

3) Authentication:
                           This process involves determining that a particular user is authorized to used a particular computer. This can include simple mechanisms such as passwords, to more complex methods using bio metric technology.

4) Hardware Cryptography:
                              It uses computer chips with cryptography capabilities intended to protect against a range of security threats.

5) Patches:
                    These are programs designed by software manufactures to fix software participation and increases ease of use.

Contemporary technology

                       Contemporary technology

INTRODUCTION

         This post covers the contents of  new and emerging technologies in the world. Its gives an overview of the most important terms related to information technology. We hope this post will be helpful to the computer user to understand basic idea of the information related terms. The words contemporary indicates modern or up to date technology available in the world. There are large sets of terms related to contemporary technology. But some of the terms broadly used and emerging trends of technology in Nepalese context are as follows:

e-Business:-

      The full form of the term is electronic business. As its name suggests business activities takes place by means of computers connected through a network. Electronic business can occur between a user and vendor through an online information services, the internet or other electronic forms. The main component of transaction is just electronic data interchange. This process user a set of standards for controlling the transfer of business documents such as purchase order and invoices orders.

               

  e-Business many be defined as the application of information and communication technologies (ICT) in support of all the activities of business. Commerce constitutes the exchange of products and services between businesses, groups and individuals. This process is a one of the essential activities of any business. In practice, e-Business is more then just e-commerce. While e-Business refers to more strategic focus with an emphasis on the functions of electronic capabilities. e-Commerce is a subset of an overall e-Business strategy. e-Commerce seeks to add revenues flow using the wold wide web or the Internet to build and enhance relationships with clients and partners to improve efficiency. There are different types of e-Business. Some of them are as follows:

    1)Business-To-Business (B2B)  
    2) Business-To-Consumer(B2C)   
    3) Business-To-Employee(B2E)
    4) Business-To-Government (B2G)
    5)Government-To-Business(G2B)
    6) Government-To-Government(G2G)
    7) Government-To-Citizen(G2C)
    8) Consumer-To-Consumer(C2C)
    9) Consumer-To-Business (C2B)

Application of e-Business:
  1. Voice over Internet Protocol (VoIP)
  2. Voice mail

  3. Web conferencing
  4. Internet shop
  5. Online marketing
  6. Electronic procurement

e-Learning:

    If the teaching and learning process is conducted by electronically is called e-learning. It supports all forms of electronically supported materials. Information and communication Technology serve as specific media to implement in the field of teaching and learning process.
          e-Learning is essentially the computer and network enable transfer of skill and knowledge throughout the world. e-learning reefers to using electronic application and processes to learn. e-learning application and process include web-based learning, computer-based learning , virtual class room and digital collaboration. The content of e-learning is delivered via the internet, extra net, audio/video material, satellite TV And CD/DVD ROM.
There are different types of e-learning, some of them are as follows:

1. Computer based training(CBT)
2. Internet based training (IBT)
3. Web based training (WBT)
4. Distance learning
5. Online universities
6. K-12 learning

Advantage of e-learning:
1. It improves performance by accessing different location.
2. It increase access by joining class at your free time.
3. It is convenience and flexible to learners.
4. Its cost is less than regular mode universities.
5. It reduces overall training time.
6. Learning forms all around the world can join on the same course.

e-Governance

    e-Government is the user of information and communication technologies to transform the traditional government by making its accessible, transparent, effective and accountable to the general people. e-Governance is a network of organization to include government, nonprofit and private-sector bodies to transform all the services in the form of electronically. In e-governance there are no distinct boundaries to involvement and deed of jobs by the government.

              Political, social, economic and technological factors of the nation determine  e- government . it establishes a relationship between government and citizens. e-Governance provides greater access to government  information and services by making the most of the government service online. This will promotes citizens to participate by interacting  more friendly with government. e-Governance will also increase government accountability by making its operations transparent which also reduces the opportunities for corruption. e-Goernence is the process of transforming government form manual system to electronic digital system. e- Government is not only used in developed countries but also successfully implementing in the developing countries like Nepal, India, Bangladesh etc . It is one stop portal such as www.nepalgov.gov.np, where citizens have access variety of information and services.

Advantages of e-Governance
1. It is easy to access data and information.
2. It become one portal for delivering government services.

3. It broadly handle Government To Government (G2G), Government To Business(G2B), and                 Government To Citizen (G2C) data and information service.
4. The government services will be made available to the citizens in a convenient, efficient and               transparent manner.
5. There will be no territory boundaries , not even bounded by geographical region.

Virtual Reality

              Virtual reality is an artificial environment that is created with software and presented to the user in such way that the user suspends belief and accepts it as a real environment. On a computer, virtual reality's primarily experienced through two of the five senses: sight and sound.
The simplest form of virtual reality is a 3‐D image that can be explored interactively at a personal
computer, usually by manipulating keys or the mouse so that the content of the image moves in some
direction or zooms in or out. More sophisticated efforts involve such approaches as wrap‐around display
screens, actual rooms augmented with wearable computers, and hap tics devices that let you feel the
display images.

Virtual reality can be divided into:
             The simulation of a real environment for training and education.The development of an imagined environment for a game or interactive story.Popular products for creating virtual reality effects on personal computers include Bryce, Extreme 3D,Ray Dream Studio, true Space, 3D Studio MAX, MAYA, Cinema and Visual Reality. The Virtual Reality Modeling Language (VRML) allows the creator to specify images and the rules for their display and interaction using textual language statements.Robotics
Robotics is the branch of technology that deals with the design, construction, operation, structural
disposition, manufacture and application of robots. Robotics is related to the sciences of electronics,engineering, mechanics, and software.  

Robotics:

       It is a branch of engineering that involves the conception, design, manufacture, and operation of
robot s. This field overlaps with electronics, computer science, artificial intelligence , mechanics,
nanotechnology , and bio engineering. Science‐fiction author Isaac Asimov is often given credit for being the first person to use the term

robotics in a short story composed in the 1940. In the story, Asimov suggested three principles to guide
the behavior of robots and smart machines. Asimov's Three Laws of Robotics, as they are called, have
survived to the present:

1. Robots must never harm human beings.
2. Robots must follow instructions from humans without violating/harm human beings.
3. Robots must protect themselves without violating the other rules.

Concept of Cyber Law

                                Cyber law

The term 'cyber' is a prefix attached to "everyday" words in order to give them a computer-based or internet online meaning, as in Cyber law, cyberspace, cyber cafe etc. Actually this prefix is derived from the word cybernetics, which refers to the study of mechanism used to control and regulate complex systems either human or machine. Cyber law is a term that encapsulates the legal issues related to use of communicative , transaction , and distributive aspects of networked information devices and technologies. Hence, it is related to the practice of law either in relation to or through the use of internet.

         Basically, cyber law deals with internet hacking, pornography, cyber-stalking, cyber-scams, online fraud, software piracy and much more. Legal experts are working in this field to help education and guide the Internet Community on crime prevention and the reporting of cyber crimes.

          In many countries, Cyber law exists in the name of information Technology Law (IT law). It is a set of recent legal enactments, which governs the process and dissemination of information digitally. These IT laws cover a broad scope of different aspects relating to computer software, protection of computer software, access and control of digital information, privacy, security, internet access and usage, and electronic commerce.

Area of Cyber Law:-
Cyber law includes many laws relating to the following issues:

1. Computer Crime law:
      Computer crime refers to any crime such as tampering, physical danger and unwanted disclosure of data that involves a computer and a computer network. Some countries have enacted the laws related to computer crime.

2. Data protection and privacy law:
       Ethical issues about storage of personal information are now becoming an increasing problem. With more storage of personal data for social networking arises the problems of selling that information for monetary gain. This gives rise to different ethical situations regarding access, security and the use of hacking in positive and negative situations. Thus, data protection and Privacy law deals with these issues.

3. Intellectual property right law:
         Intellectual property refers to the creations of the human mind such as musical, literacy , photographic and artistic works; discoveries and inventions; and words, phases, symbols and designs etc. Intellectual property rights protect the interest of creators by giving them property rights over their creations. Common type of intellectual property right law include copyrights, trademarks, patents, industrial design rights etc.

4. Electronic and Digital signature law:

          Digital signature is a way of authenticating that an electronic message really came from the Peron it claims to have come from. A digital signature can be encrypted with your private key. The recipient can decry  the message with your public key to verify that it is really you. This law deals with the electronic and digital signature in e-Commerce or electronic transaction.

5. Telecommunication law: 
        Communication through the telecommunication also uses the internet. cyber law also deals with the laws related to the telecommunication.