Role of Computers in Education

Role of Computers in Education

Computers have revolutionized in education sector too. The concept of the conventional classrooms is changing. The old classroom has given way to a modern classroom in which computers are used for enhancing ideas and giving a more real-life and visually oriented education. An important factor in using computers is the intellectual advantage resulting from their use in the conventional classroom everything was taught on the black board. Only verbal explanation was possible. This method had a lot of limitations in conveying ideas. CBT is an acronym for Computer Based Training. This uses multimedia and classroom projectors containing training material beneficial for students and teachers on various subjects.

With the Internet revolution, education has also moved on the World Web platform. Many universities are using the web for distance education and distribution of study materials and syllabi to students. Following are some of the key advantages in using computers in education.

♦ Interactive classroom

♦ Conduct online classes

♦ Can do science projects using software

♦ Can search and study about interesting subjects from Internet

♦ Webinars

♦ Softwares are available that demonstrate topics with solved examples in science and Mathematics

Education is now considered as a continuous learning process. Age is not a criterion in modern education. As knowledge can become obsolete after a few years, education must focus on continuous learning. In educational institutions computers are used as teaching aids, information resource and computing and research tool.

When computer is utilized as an education aid it is called as 'Computer-Assisted Instruction' (CAI). The subject material is displayed on the Monitor. The computer also asks questions to test the students. When a student gives correct answer, the computer gives some comments to indicate that the answer is correct. If the answer is not correct, the computer gives some error signal. The CAI programs can be prepared in a variety of modes, such as tutorial, discovery, problem solving, modeling, and drill and practice mode.

In tutorial mode, the computer presents new ideas followed by test questions. In discovery mode, the computer presents information and asks students to draw conclusions. In problem solving mode, computer allows students to apply some concepts in solving a problem. In modeling mode, a process or a system is presented mathematically to make its analysis. Students are allowed to change variables to see their effects. In drill and practice mode, it is assumed that the skill in question is known but repetition is essential to have command over the subject. The interactive feature of the computer makes computer-aided teaching attractive. Computers can repeat the presentation of the material as many times as desired. This helps students make certain concepts clearer if they are not clear in earlier attempts.

Other attractive features of computers are their multimedia capabilities - particularly colour graphics ability. Pictures can move, rotate, computer can speak; all these features attract students. Graphics help students to see three-dimensional figures and view from different angles. Figures can be enlarged or reduced.

Computers are widely used for computation, design and research. The word processing package is used for preparing text, typing thesis, office and administrative work, preparation of test questions etc. Data processing capability of computers are used by students, teachers and research scholars to analyze, manipulate and process data. Information stored in databases serves as a learning resource for students. Question banks may be prepared and stored in the computer.

Education is now combined with entertainment and is often called ‘Edutainment’. Edutainment is broadly defined as software, electronic books and interactive games which have an educational component. This new form of education through computers is more effective than the conventional class room learning. The student can decide when and where he or she wants to listen or participate. Students both residential and non-residential can attend lectures broadcast to their homes or work places and get reference materials from distant locations using computers. Local and wide area networks will enable universities to integrate many aspects of education. Computers have revolutionized the teaching profession. Teachers use computers to record marks, calculate averages, record attendance and access the progression of student in online programs and assessments.

Computers in Examinations

Computers are widely used for processing examination results. It is also used by Universities to set question papers for different subjects from a question bank stored in the database of computers. Questions can be selected at random for different subjects. After evaluation, the marks are also entered into the database of students registered. The computer can decide classes, distinctions, ranks etc. of the students and prepare and print the mark lists.

Computers are also widely used in competitive examinations, entrance examinations etc. which use objective type questions with limited number of choices of answers for each question. Special types of answer sheets are used. It contains question number followed by a number of bubbles representing the choice of answers. A candidate has to shade a bubble of his choice. Optical mark readers are used to read the answers represented by shaded bubbles and the data are first stored in the computer. Data are then processed by a computer program to prepare the rank list. The whole process of evaluation takes only a few hours though thousands of candidates’ answers are to be evaluated.

Role of Computers in Business

Role of Computers in Business

The main aim of businesses is the look for ways to raise the profit and also for market reach. The development of technology will further boost the businesses to achieve various goals. Technology can be further utilized for their profits and market reach. People can promote their products by using the latest technologies with the help of computer. The growth of money transactions from the ancient barter system to paper currencies to plastic money (debit, credit cards) played a major role in the history of business. This transformation has improved the ease of both the buyer and the seller. Electronic commerce or e-commerce has been the consequence of search of more proficient ways of doing business. Mostly it is buying and selling by means of electronic communications. Today, electronic commerce dominated as one among the major business field in the world. Examples of gigantic companies doing online businesses are Amazon, Ebay, Flipkart and so on.

Take a look at the application of computers that helps the business organizations. It allows an organization to manage the information and communication resources with all its branches, including staffs, clients, bankers, government offices, advertisement agencies and the public. When a firm does business electronically, they can do the business from anyplace, 24 hours a day, 7 days a week. Thus from small shops to international companies and corporations of any industrial sector are doing their business with fully integrated IT organizational structure.

The two fundamental business computing systems are office automation and Management Information Systems.

1. Office Automation:

Office automation is defined as using computer and communications technology to help people better use and manage information. People who use office automation are often called knowledge workers - senior executives, managers, supervisors, analysts, engineers and other white-collar office workers. In most offices, information (often in paper form) is the end product and is essential for conducting the company's business. Office automation systems keep track of the information originating in various operations throughout the company, such as order processing, accounting, inventory and manufacturing. Office automation provides knowledge workers with information - producing systems to collect, analyse, plan, and control information about the many facets of the business, using text, voice, graphics and video display technology.

There are five primary technologies used in organizing information in office automation.

♦ Text, may be written information  

♦ Data, may be described in numbers or further non-text forms

♦ Graphics, may be images, sketch, charts or photos

♦ Audio, may be telephone conversations, voice mail or other voice recognition methods

♦ Video, may be slideshow images, video recordings or teleconferencing

In the past these kind of information were created using diverse technologies. Data, such as sales reports, were provided by the central computer. Charts and graphs were either hand drawn or created using 35mm slide photography and videotapes were used for training. Audio was restricted to the phone or tape recording. It was not possible to combine these various forms of information.

It was the computer that made their combination possible. What the computer produces is called an electronic document, which is a self-contained work. It may be a simple memo printed on paper or transmitted via electronic mail. Or it may be a more complex document, with graphics or even video annotated with comments. Such application software is also called as 'Groupware’. It allows networked PCs and work stations share information and electronic documents.

Office automation systems are comprised of many distinct sub systems: text management systems, business analysis systems, document management systems and network and communications systems.

2. Business Analysis Systems:

It allows managers to understand the business environment and take effective decisions. Spreadsheets are often used for analyzing cost and benefits and for creating budgets.

Another software called the Decision Support System (DSS) helps managers to extract information from the various management information system data bases, analyze it and then formulate a decision strategy for business planning. An 'expert system' is a program that can provide expert advice to the user. An 'executive support system' is an information system that consolidates and summarizes ongoing transactions within the organization.

3. Document Management System:

It helps in filing, tracking and managing documents.

4. Network and Communication Management System:

It includes telephone, electronic mail, voice messaging systems, teleconferencing and fax machines. They can communicate in real time via telephone or computer controlled PBX telephone systems to record a digital message and leave it in the recipient's mail box.

5. Text management systems

It is a computer system designed to work with the written or typewritten word. It includes typewriters, word processing systems, PCs with word processing, desktop publishing and text editing systems. These are used for tasks like writing memos, notes, letters and other short documents, printing envelopes and labels, preparing pre-printed forms such as invoices, composing complex documents such as proposals and reports, retrieving and editing documents such as contracts, creating display documents like newsletters etc.

6. Management Information System

MIS (Management Information System) is a computerized database of financial information which is organized and programmed and are used today in all businesses. Some of the benefits of integrating computer systems with organizational structure are:

♦ Grow business functions to world class

♦ Access to the complete world’s finest of class, expertise, knowledge and resources

♦ Overcome the time and distance limits

♦ Make use of technology for enhanced management information

♦ Increased profits

Role of Computers in Entertainment

Computers have now become an integral part of the entertainment industry. They are used for creating dazzling special effects in movies. They are used to edit movies, create full length cartoon movies, multimedia presentations etc. Computers are used to simulate games and to try out different game strategies. Thus the use of computers in the entertainment field - movies, music, presentations, sports and games - has increased over the last decade and now computers play a vital role in these fields.

Computers are used in film industries for music composition, film editing and creating animations in cartoon films. Here, Computer graphics and virtual reality modeling are the techniques used to make scenes, which cannot be produced in real. This gives stimulating special effects in the movie. Almost all the films produced today are using computers.

Multimedia systems incorporate text, voice, video, graphics and music to create an integrated platform. One important application of multimedia technology in research and entertainment is the electronic encyclopedia. Such an encyclopedia includes colorful imagery and animations with description in text. It also makes easy navigation through hyperlinks. A hyperlink is a highlighted text or image, which is linked to related page containing information. When the user makes a mouse-click on the hyperlink the page is brought to the display. Role of computers in the field of Entertainment are explained below.

 

Computers in Movies

 

Movies now contain many visual tricks and treats that could never be accomplished without the aid of computers. The film makers can then integrate these back-grounds and characters with the real actors effortlessly. Thus many special effects that arise from the director's creativity and imagination become real. Thus computers and information technology have helped the film industry in reducing the cost of production. They also reduce the time taken to make movies. In the past, to create a cartoon movie, the animator had to draw each and every frame manually, and it took many years to complete. But with today's computerized animation packages, the job is very easy. Now computers are used in almost all phases of movie making, writing scripts, creating special effects, editing, adding sound effects and so on.

 

Computers in Music

 

Any musical composition that we hear today is true when the piece of music is composed, when it is played or when it is reproduced. Most songs have some sort of electronic instrumentation. The same is the case with music in TV commercials, cartoons and popular movies. Computer applications are taking an active part in the music of our age. A synthesizer is a musical instrument that generates music electronically. In 1983 major electronic instrument manufacturers developed a communication standard called Musical Instrumental Digital Interface (MIDI). The problem of interfacing electronic musical instruments manufactured by different companies was solved with this standard developed. Computers are also very useful in creating patch librarians - programs that organize and store sounds. Using this, one can store thousands of synthesized sounds in a file. This information can be downloaded via MIDI into synthesizer and back.

Another MIDI oriented application is the sequencer. A sequencer memorizes anything you play, and plays it back on command. Later we can add melody lines and different instruments to the already existing piece of music. There are many music composition languages which resemble programming languages. Today digital audios are widely used. Digital audio in recording applications is stored on different recorders including Compact Disc (CD), DAT, DCC and MiniDisc. MP3, AAC, Ogg Vorbis, and AU files are different formats that can be created with the help of a computer. It can be kept in any storage devices.

 

Computers in Art

 

Since the stone age, art has evolved with mankind. The tools and the medium have changed but the function of art remains the same - arts transform and transport the viewers to alternate perceptions of reality. Computer art can be classified into two major categories - computer graphics and image processing. Computer graphics is used in computer animation. People involved in computer graphics need programming knowledge as well as understanding of perspective, shading, hidden-line, hidden-surface removal, shadowing, ray tracing etc. in image creation. Image processing on the other hand takes advantage of powerful easy to use software packages like Corel Draw, Microsoft PhotoDraw, Adobe Photoshop, Fractal Painter etc. The interactive art facility provided by the computer allows one to be the director and to experience the work in his own "time". The new media allows the artist to invoke emotions unreachable with a brush.

Computers in Home Entertainment

Regardless of how people say they use home computers, surveys suggested that they use them mostly to play games, browsing internet and watching videos. Computer games and video game machines (which are just special purpose computers) represent a huge industry with dazzling graphics, digitized sound and sophisticated effects, many of today's computer games represent state-of-the-art software. Various means of entertainment for children are computer games, interactive videos, video games, flight simulators and electronic puzzles. Some software helps people to learn from entertainment.

Types of Computers based on Size and Working Principle

Types of Computers based on Size and Working Principle

Types of Computers based on Working Principle

Based on the working principle, there are three categories of computers: Digital computers, Analog computers and Hybrid Computers

Digital Computer

The general-purpose computers that we use today are digital computers. They represent all information in the form of digitals. They are built to operate on numeric codes. They do any task by basic operations like counting, addition etc. The important advantage is that they are much faster and accurate.

Based on the purpose, digital computers are classified into two types: Special Purpose Computers and General Purpose Computers. Special purpose computer is a computer that is designed to perform a specific task. They permanently store the instructions. So they can work efficiently. Such computers find application in process control and instrumentation. Most of these computers have a lot of firmware and may use specialized processors.

Analog Computers

Analog computers operate by the principle of measuring continuous quantities like voltage, current, pressure, temperature etc. They are less accurate and flow. They are used in engineering and science applications. An electronic weighing scale is an example of an analog computer.

Hybrid Computers

Hybrid computers combine the features of digital and analog computers. Some calculations take place in analog and other calculations in digital principle. Bio-medical equipments make use of both analog and digital techniques. They accept input using analog mechanism, then convert data to digital form and process the data by means of permanent programs. They have dedicated processor chips and memory.

 

Types of Computers based on Size

 

General-purpose computers come in various sizes and capabilities (Computing power). Each type has it's own architecture and are used depending on the size of applications. For example small microcomputers are used by individuals; where as giant super computers are used by large organizations for extremely large scale applications. The terms that we use to describe the different types of computers are:-

➢ Microcomputers

➢ Workstations

➢ Minicomputers

➢ Mainframes

➢ Supercomputer

Microcomputers

Microcomputers are the small computers that are commonly found in offices, classrooms and homes. The term personal computer or PC is synonymous with microcomputer. However PC has a more specific meaning they reside on desktops.

A microcomputer is built around a microprocessor chip, which is the CPU. They are compact models with a monitor, CPU, memory and disk drives all in one unit (called system unit).

The IBM-PC compatibles and Apple macintosh are popular example of personal computer models.

Microcomputers are the most economical. Their uses are, for small business applications, as a home computer for entertainment, as a part of the 'home office'. They also find use in schools for educational purpose. Top business executives carry small laptop micros for record keeping and presentations. For serious professionals, they are also suitable for workgroup computing and collaborative work.

Workstations

Between minicomputers and microcomputers, in terms of processing power, is a class of computers known as workstations. Workstations differ significantly from microcomputer in the design of their CPU. They are based on a philosophy of CPU design called reduced instructions set computing (RISC), which results in faster processing of instructions. Companies like IBM, sun microsystems, DEC and Hewlett packard are the leading manufacturers of workstations.

Minicomputers

The power of minicomputers lies between microcomputers and mainframes. They are mainly used as multiuser systems. They have greater storage capacity and larger memories. They use specially designed CPUs. They are ideal for organizations and companies who need to maintain large volumes of data in databases. The major minicomputer manufactures are IBM, DEC, Data General etc.

Mainframe Computers

Mainframes are the largest type of computer in common use. They are designed to handle tremendous amounts of input, output and storage. Like minicomputers they also have large number of terminals through which multiple users can share their usage.

Mainframes are used in huge companies and government departments for running centralized applications. For example, data is a central database stored in the mainframe can provide shared access to all departments of various offices of an organization.

Inspite of their tremendous power, they are prohibitively expensive. Another drawback is that a breakdown of the mainframe would affect the entire organization.

Due to these disadvantages, the mainframe based computing has manufacturer of mainframes, IBM 4300 series, IBM sierra 3090, IBM ES 9000 series etc are examples.

Super Computers

A Supercomputer is the most powerful computer available. These machines are extremely fast and hence suitable for processing huge amounts of information. A super computer system uses a special architecture that enhance speed and capability of the machine. They make use of parallel processing with multiple CPUs or single CPUs having parallel architecture. Due to this they can perform billions of instructions in a second.

Scientists use super computers to build models of complex processes (simulation). One such process is nuclear fission. Here a super computer can simulate the actions and reactions of millions of atoms as they interact. Other applications are in weather forecasting, space exploration, geographical information systems etc.

The CRAY X-MP 416 CRAY I, NEC CX / 44, Blue Pacific of IBM and CRAY 2 were some of the early supercomputers. Indian Scientists have also done considerable research in the field of supercomputers. Scientists of C-DAC (Centre for Development of Advanced Computing - An Institution under Department of Electronics, Government of India) have succeeded in building a super computer named PARAM. Another Indian super computer is Anupam. At present it is used for weather predictions. Below are the lists of Super Computers used in India.

➢ Sahasrat (CRAY XC40) (1.46 petaflops)

➢ HPC (860 teraflops)

➢ Cray XC-30 (558.7 teraflops)

➢ PARAM YUVA II (524 teraflops)

➢ PARAM Ishan (121 teraflops)

➢ Virgo (97 teraflops)

➢ PARAM SHIVAY (38.1 teraflops)

➢ PARAM Kanchenjunga (15 teraflops)

Generation of Computers Notes

Since 1946, which marked the development of the first electronic computer namely the ENIAC (Electronic Numerical Integrator and Calculator), almost each decade has seen significant advances in computer technology. The term "Computer generation" is used to denote the technology that emerged during a particular period with considerable improvement in hardware, software and computing concepts. Thus each decade since 1946 gave rise to a new generation of computers.

The First Generation Computers (1946 - 55)

ENIAC was the first electronic general purpose computer to be put to use. It was developed by a team led by professor Eckert and John.W. Mauchly at the university of Pennsylvania in U.S.A. It had a very small memory and was used for preparation of artillery trajectory tables.

The first generation computers used vaccum tubes and machine language was used for giving instructions. They used the stored program concept proposed by John Von Neumann. This concept is storing data and instructions in the computer memory. Initial applications of computers were in science and engineering. The concept of operating system had not emerged during the first generation. In order to use the computer, one had to know the details of its structure and working.

Because vacuum tubes were used, computers were huge and also required more power. The failure rate was high. Vacuum tubes also generated a lot of heat and could not operate for long without cooling.

The ENIAC itself used around 18000 vacuum tubes and weighed 30 tons.

In 1950, the first computer that used the Von-Neumann concept of stored programs named EDVAC (Electronic Discrete Variable Automatic Computer) was built. With this, operation of the computer became faster.

The EDSAC - short for Electronic Delay Storage Automatic Computer was developed by Professor Wilkes at Cambridge University in 1949. This also used the stored - program concept.

The UNIVAC - I (Universal Automatic Computer) became operational in 1954. This marked the beginning of commercial production of stored program computers. With the advent of UNIVAC - I, computers began to be used for commercial applications. In the period from 1954 to 59, many businesses acquired computers for data processing applications.

The Second Generation Computers (1956 - 65)

The computers of the second generation began to appear in the later half of the 1950's. They were made smaller and faster and had greater computing capacity. The practice of writing programs in machine language was replaced by higher-level programming languages. The vacuum tubes were replaced by tiny solid state components called transistors.

The invention of transistor by John Bardeen and William Shockley in 1947 was a big revolution. Transistors were highly reliable and required less power. Also they were faster than vacuum tubes. The invention of magnetic core memory was another important event that happened during the second generation period. These are tiny ferrite rings that can be magnetized in either direction for representing 1 and 0 magnetic cores were used to construct large random access memories. Memory capacity in the second generation was about 100 kilo bytes.

The higher reliability and large memory capacity of computer led to the development of high level programming languages (HLLs). Languages like FORTRAN, COBOL and ALGOL were developed during this generation.

Magnetic disk and tape storage medium began to be used. Batch processing operating systems were developed, which automated the operations of the computer.

Commercial applications rapidly developed during this period and dominated computer use by the mid 1960s.

Some of the second generation computer were IBM 1401, IBM 1620, IBM 7094, RCA 501, CDC 3600 etc.

The Third Generation Computer (1966 - 75)

The third generation computers replaced transistors with 'Integrated Circuits' or ICs. The Integrated Circuit was invented by jack Kilby at Texas Instruments Inc. in 1958. An Integrated circuit consists of electronic circuits fabricated on a single chip of a semiconductor material called silicon. All electronic components like transistors, resistors and capacitors were fabricated on the silicon chip (also called silicon wafer). From small scale integrated circuits which had about 10 transistors per chip, technology developed to medium scale integrated circuits with 100 transistors per chip. The size of main memories reached about 4 mega bytes. Magnetic disk storage capacities increased to around 100 MB CPUs became more powerful.

Time sharing operating systems, that allowed multiple uses to work simultaneously with a computer became popular. Computer began to be used increasingly for many on-line applications. Other application areas were production and manufacturing, inventory control, air-line reservation systems etc.

The system 360 family of mainframe computers was announced by the IBM. Other models were ICL- 1900 series, IBM - 370, the DEC PDP 11 etc.

The Fourth Generation Computers (1976 onwards)

The development of VLSI (Very Large Scale Integrated Circuit) technology led to the creation of microprocessor chips. These chips packaged a million transistors in one chip. The size of the main memory also increased tremendously. The microprocessor marked the beginning of a new generation of computer- the fourth generation. Powerful personal computers and mini computers emerged. In 1976 Apple computers produced their first PC named Apple-I. By the end of 1977, machines like Apple II and TRS-80 model from Tandy corporation were popular micro computers.

Two companies Intel and Motorola began producing new micro-processors. In the early 1980s, many microcomputers were built around these processors. These computers used much more powerful operating systems. In 1981, the IBM announced its first desktop model microcomputer or the PC (Personal Computer). This became the de-facto industry standard for PC's. The IBM-PC dominated the world market. However there was a close competitor to IBM - the Apple computer.

Whereas IBM-PCs made use of one of the microprocessors from the Intel family, Apple-PCs used Motorola processors.

The second decade of the fourth generation (1986 to present) brought great increase in the operating speed and capability of microprocessors and the size of main memory. Both main memory and hard disk capacities went up several times each year. Microprocessors have undergone major architectural changes.

Powerful and versatile operating systems were developed which exploited new features of the processors. Advanced programming languages were developed along with new programming concepts like object oriented programming (OOPs).

The Fifth Generation Computers (Present and Beyond)

The development of ULSI (Ultra Large Scale Integration) microprocessor marks the beginning of Fifth Generation Computers. The super human thinking computers found in science fictions don't exist. But science fictions have become reality. Scientists are now trying to develop computers that can solve unstructured problems. These are the types of problems that people solve by trying various alternatives and learning from their mistakes. Until recently, only Human Intelligence could do this. Efforts to design computer systems that exhibit human intelligence are classified under Artificial Intelligence (AI). Researchers are trying to develop neural - network computers - machines with circuits - patterned after the complex interconnections that exist between the neurons in the brain.

The central concept of fifth generation computers is Artificial Intelligence. Researchers are working to develop computers that have intelligence close to human beings. But this field is still in fancy. Artificial Intelligence based systems and expert systems (or knowledge- based systems) are capable of gaining knowledge from surroundings and react to events depending on situations. Already, robots have been developed and deployed in many applications. Robots that understand the verbal commands of their master have become a reality. The use of superconductors makes artificial intelligence a reality. Innovations in Quantum computation, molecular technology and nanotechnology are the future developments of computers.

Examples of artificial intelligence are

(1) Medical diagnostic packages that diagnose diseases and recommend treatments

(2) Geology packages that can predict mineral deposits

(3) Natural language programs that allow users to replace complicated computer commands with plain natural language commands.

(4) Voice recognition that is being used today.

Communication Systems Lab Viva Questions

Viva Questions on Communication Systems Lab

1. Draw the block diagram of an analog communication technique. Discuss about the drawbacks of analog communication techniques?

The block diagram of an analog communication system is:

The main drawbacks of analog communication techniques are: we cannot trust analog communication for all time. The effect of noise is more on the transmitted signals. The power required for the transmission of the signal is very high, this will yields for high length transmitting antennas which makes the transmission section more complex. The circuit complexity and cost are high for analog communication.

2.  List the main advantages of digital communication techniques?

a. The main advantages of digital communication are:

b. It is highly reliable.

c. The effect of noise is very less, hence yields to high SNR.

d. The power consumption is very less.

e. The circuit complexity is very less because various Digital ICs are used.

f. It requires less cost.

g. The error detection and correction is possible.

3. Which types of digital modulation techniques you know?

The different types of digital modulation techniques are:

a. Amplitude shift Keying (ASK)

b. Frequency Shift Keying (FSK)

c. Phase Shift Keying (PSK)

d. Pulse code Modulation (PCM)

e. Differential Pulse Code Modulation (DPCM)

f. Delta Modulation (DM)

g. Adaptive Delta Modulation etc...

4.  With the help of a block diagram, explain the process of converting analog signal to digital signal?

For the conversion of analog signal to digital, first the analog signal is passed through an anti aliasing filter. Then this signal is passed to a Sampler circuit, then to a quantizer and  encoder.

5.  Discuss the functions of a sampler and quantizer?

We know that sampler and quantizer are the basic blocks of an analog to digital converter. A sampler circuit converts a continuous time signal into discrete time signal and the function of a  quantizer is to convert a continuous in amplitude signal into discrete in amplitude signal.

6.  Which types of Coding techniques are familiar to you?

The different coding techniques in communication system are:

a. Pulse code modulation,

b. Differential pulse code modulation,

c. Delta modulation,

d. Adaptive delta modulation

7.  What you know about the Sampling process?

Simply we can say that sampling process is similar to the process of cutting a bread into slices. Technically in terms of signals, we can say that the process of converting a continuous time signal into discrete in time signal is called as Sampling. In order to perform the sampling process, the analog signal is fed to a sampler circuit (switch).

8.  State sampling theorem?

Sampling theorem states that in order to reconstruct the continuous time signal from a discrete time signal, the sampling frequency taken should be more than or equal to twice of the maximum frequency of the continuous time signal frequency.

f_s  ≥ 2f_m

Violation of sampling theorem yields to aliasing effect. We cannot reconstruct the original signal from its samples, if sampling theorem is not maintained.

9.  What you know about Nyquist Rate in sampling process?

Nyquist rate is the sampling rate at which the sampling frequency is twice that of the maximum frequency component of the continuous time signal.

f_s  = 2f_m 

If nyquist rate is maintained for the sampling process, then that is said to be a perfect sampling process.

10.  How many types of samplings are you familiar. Explain?

The different types of samplings are:

a. Impulse Sampling:

The process of impulse sampling is done by multiplying the input signal x(t) with impulse train of period 'T'.

b. Natural sampling:

The process of sampling in which pulse have finite width equal to τ is known as natural sampling. Sampling process is done with respect to a carrier signal, which is in digital form.

c. Flat top sampling:

At the time of transmission of signal through channel, noise is introduced at top of the transmission pulse. This noise can be easily remove if the pulse is in the form of flat top. Thus, the top of the samples are flat, in other words, we can say that they have constant amplitude.

11.  Discuss in detail about the aliasing effect and explain how it is rectified?

At the time of sampling, if the sampling theorem is not satisfied; i.e if imperfect sampling occurs, the signals will be interfered in frequency domain. This is called aliasing effect in sampling. The aliasing effect can be rectified, if sampling theorem is satisfied;

f_s  ≥ 2f_m

The aliasing effect can also be rectified as first by passing signal from anti aliasing filter before sampling.

12.  How many types of analog pulse modulation methods you know. List all?

The different types of analog pulse modulation methods are:

a. Pulse Amplitude Modulation (PAM)

b. Pulse Width Modulation (PWM)

c. Pulse Position Modulation (PPM)

13.  What you know about Pulse amplitude modulation?

In pulse amplitude modulation, the height of the carrier pulse (amplitude) is proportional to amplitude of message signal. In other words, in PAM, the amplitude of the carrier and message signals are directly proportional to each other.

14.  What you know about Pulse width modulation?

In pulse width modulation, the width of the carrier pulse is proportional to the amplitude of message signal.

15.  Discuss about Pulse position modulation?

In pulse position modulation technique, the position of carrier pulse is proportional to the amplitude of message signal.

16.  Give the comparison of PAM, PWM, PPM?

The different parameters of PAM, PWM and PPM are shown below:

17.  Discuss about Amplitude shift Keying (ASK) ?

The ASK modulation technique represents digital data in carrier wave as variations in amplitudes. In other words, we can say that in ASK, '1' represented by transmitting a fixed amplitude carrier wave with constant frequency for the bit duration.

18.  Illustrate about Phase Shift keying (PSK) technique?

In PSK, the digital data is represented as variations in phase shift in the carrier wave. In other words, in PSK, '1' is represented by a 0 phase shift carrier wave and '0' is represented by a 180 phase shift carrier wave. Both the representation is for the bit duration with constant frequency.

19.  Discuss about Frequency Shift keying (FSK) ?

In FSK, the digital data is represented as variation in frequency in carrier wave. In other words, we can say that for '1' more than carrier frequency is used and for '0' less than carrier frequency is used.

20.  Discuss about Binary Phase Shift Keying (BPSK). Show the technique?

For BPSK modulation technique, for each bit of binary data (0 & 1), the carrier phase will be changed. The two different shifts are 0 and 180 degrees.

21.  Discuss in detail about Quadrature Phase Shift Keying (QPSK). Show the technique?

In QPSK, we know that for each two bits of binary data (00, 01, 10 & 11), carrier phase will be changed to four different shifts : (45, 135, -45, -135).

22.  Give the differences between Bit Rate and Baud Rate?

We know that the bit rate represents the number of bits per second. Baud rate can be defined as the number of symbols per second.  i.e., we can say that in communications the no. of bits transmitted per sec is known as Bit Rate (units bps). The number of times a signal (carrier) changes its state per sec is known as the Baud rate.

23.  What is bandwidth of BPSK signal?

The bandwidth of a BPSK signal is 2F_c, where F_c is the carrier frequency.

24.  Give the comparison of ASK, PSK and FSK ?

Bandwidth	ASK< PSK < FSK
Power	ASK <PSK = FSK
Probability of error	ASK > PSK > FSK
Signal to Noise Ratio	ASK < PSK < FSK

25.  Justify the reason behind calling Amplitude Shift keying (ASK) as ON-OFF keying?

Simply we can say that ASK acts like a switch. The reason is that when input data is than in ASK if the symbol is 1, then output is carrier and if input is 0, then the output is also zero. Hence its looks like a switch. This switches to ON state when input is 1 and to OFF state when input is zero.