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Microprocessors & Interfacing Syllabus

2010-11-25T13:36:00.001+05:30

B.Tech. (ECE) V Semester

MICROPROCESSORS AND INTERFACING

Course Code: EUREC501 Category: CE

Credits: 3 Hours: 3 per week

Department: ECE

UNIT-I

Intel 8085 microprocessor: Evaluation of microprocessors, Architecture of 8085, pin diagram, addressing modes of 8085.

UNIT-II

Intel 8086 microprocessor: 8086 internal architecture, addressing modes, pin diagram, minimum mode and maximum mode of operation, timing diagrams.

UNIT-III

8086 Programming: Instruction set of 8086, assembler directives, program development steps, constructing the machine Course Codes for 8086 instructions, writing programs for use with an assembler, , writing and using procedures and assembler macros.

UNIT-IV

8086 Interrupts: 8086 interrupts and interrupt responses, priority interrupt controller Intel 8259A.

UNIT-V

Programmable devices and Interfacing of I/O: Addressing memory and ports in microcomputer system, programmable peripheral interface 8255A, programmable timer/ counter 8253/ 8254, serial I/O 8251 USART, DMA controller 8237/ 8257, Interfacing of A/D and D/A converters to 8086 microprocessor. Interfacing a microprocessor to keyboards.

Text Books:

1. Ramesh S Goankar, “Microprocessor Architecture Programming and

Applications with the 8085, Perman International Pvt.Ltd.

2. Douglas V Hall, “Microprocessors and Interfacing: Programming and Hardware”, 2^nd edition, TMH.

Reference Books:

1. Micro computer systems, The 8086/8088 Family Architecture, Programming

and Design – Y.Liu and G.A. Gibson, PHI, 2^nd edition.

2. Barry B. Brey, “The Intel Microprocessors 8086/8088, 80186/80188, 80286, 80386, 80486,and Pentium processors. Architecture, programming and interfacing”.

3. 8086 Micro Processor -Kenneth J. Ayala, Penram International/ Thomson, 1995.

Computer Architechture & Organisation Syllabus

2010-11-25T13:35:00.001+05:30

B.Tech. (ECE) V Semester

COMPUTER ARCHITECTURE & ORGANIZATION

Course Code: EUREC506 Category: CE

Credits: 3 Hours: 3 per week

Department: ECE

UNIT-I

Register Transfer and Micro operations: Register transfer language - register transfer - bus and memory transfers – arithmetic micro operations - logic micro operations – shift micro operations – arithmetic logic shift unit

UNIT-II

Basic Computer Organization: Instruction Course Codes – computer registers – computer instructions – timing and control – instruction cycle – memory reference instructions – input-output and interrupt – complete computer description

UNIT-III

CPU Organization: Introduction - general register organization – stack organization - instruction formats – addressing modes – data transfer and manipulation – program control – Reduced Instruction Set Computer(RISC) – Complex Instruction Set Computer(CISC)

UNIT-IV

Micro programmed Control: Control memory – address sequencing – microinstruction format – vertical and horizontal microinstructions – micro program example – design of control unit

UNIT-V

Memory and I/O Organization: Memory hierarchy – main memory – associative memory – cache memory – virtual memory, Peripheral devices – input/output interface – asynchronous data transfer – modes of transfer – priority interrupt – direct memory access .

Text Book:

1. Mano, Morris M., Computer System Architecture, 3^rd ed. Pearson Education Asia, 2000.

References:

1. Stallings W., Computer Organization and Architecture, 6^th ed. Pearson Education Asia, 2000

2. Hamacher, V.C., Z.G.Vranesic, and S.G.Zaky, Computer Organization, 3^rd ed, McGraw-Hill, 1990

Antennas and Wave Propagation Syllabus

2010-11-25T13:32:00.003+05:30

B.Tech. (ECE) V Semester

ANTENNAS & WAVE PROPAGATION

Course Code: EUREC505 Category: CE

Credits: 3 Hours: 3 per week

Department: ECE

UNIT-I

Antenna Fundamentals: Antenna Radiation Mechanism, Properties of Antennas, Directional Characteristics of Dipole Antennas, Traveling Wave Antennas, Effect of the Feed, Standing Wave Antennas, Antenna Gain, Directivity, Effective Area, Antenna Terminal Impedance, Characteristic Impedance of Antennas, Antenna Temperature and Signal to Noise Ratio.

UNIT-II

Radiation:Potential Functions, Electromagnetic Fields, Potentials Functions for Sinusoidal Oscillations, Alternating Current Element, Power Radiated by a Current Element, Applications to Short Antennas, Assumed Current Distributions, Radiation From Quarter Wave Monopole, Radiation from a Half-wave Dipole, Far and Near Fields.

UNIT-III

Antennas for Communications and Radar Applications: Concept, construction, design principle, applications, limitations and parameters of - Dipoles, Folded Dipoles, loop antennas, V - Antennas, Rhombic and Yagi-Uda Antennas, Log – Periodic, Helical Antennas, Reflector Antennas, Lens and Horn Antennas, Slot and Micro-strip Antennas. Antenna Measurements: Antenna parameter measurement test setup, anechoic chamber, GTEM cell, antenna test ranges, sources of error in antenna measurements, measurement of - Input and Mutual Impedances, Radiation Pattern, Gain, Phase Front and Polarization.

UNIT-IV

Array antennas and Synthesis: Concept of Array antennas, Uniform Linear Arrays, Broadside and End-fire Arrays, Radiation Characteristics, Side-lobe and Beam-width Requirements, Multiplication of Patterns, Binomial Arrays, Effect of Earth on Radiation Patterns, Methods of Array Synthesis, Tchebyscheff Distribution, Super Directive Arrays, Fourier Transform Method, Woodward Method.

UNIT-V

Wave Propagation: Ground Wave Propagation, Estimation of Ground Wave Field Strength, Space Wave Propagation, Effect of Curvature of Earth, Shadow Zone and its Effects, Atmospheric Effects on Space Wave Propagation, Duct Propagation, Wave Tilt of Surface Wave, Inonospheric Wave Propagation, Inonospheric Layers, Reflection and Refraction of Wave in Ionosphere, MUF, Skip Distance, Critical Frequency, Virtual Height, Effect of Earth’s Magnetic Field, Fading, LOS and Faraday’s Rotation.

Textbooks:

1. EM Waves and Radiation Systems, E. C. Jordan and K. G. Balmain, PHI–N. Delhi, 1997

Reference Books:

1. Antennas & Wave Propagation, G S N Raju, Pearson Education, 2004

2. Antenna Theory and Practice, Rajeswari Chatterjee, Wiley Eastern Ltd. – N. Delhi

3. Electronic and Radio Engineering, F. E. Terman, McGraw Hill – N. York,

Data Structures Syllabus

2010-11-25T13:32:00.001+05:30

B.Tech. (ECE) V Semester

DATA STRUCTURES using ‘C’

Course Code: EUREC504 Category: CE

Credits: 3 Hours: 3 per week

Department: ECE

UNIT-I

Arrays: Organization and use of one-dimensional arrays, operations, two dimensional and multidimensional arrays – Algorithms of all operations on linear arrays.

UNIT-II

Structures, pointers and files: definition of structures and unions, programming examples; pointers, pointer expression, programming examples; file operations, process.

UNIT-III

Linear Data Structures: Stack representation, operational algorithms, arithmetic expression: polish Notation. Queue representation, operations algorithms deques, priority queues, circular queues. Linked list representation operations algorithms double linked and circular lists.

UNIT-IV

Non-linear Data structures: Tress, Binary tree representation, tree traversals, Huffman’s algorithms conversion of general tree to binary tree. Graph representation, Warshall’s algorithms, shortest paths, linked representation of a graph, operations of graph, traversing a graph.

UNIT-V

Sorting, Searching and Unix operating systems: Bubble sort, quick sort, hcap sort Linear search. Binary search, Study of Unix operating system: file system protection, Unix shell programming.

Text Books:

1. Programming in ANSIC – E Balaguruswamy

2. Data Structures using C, - A.M. Tanebaum and others 2003

Reference Books:

1. Data Structures – Schaum’s outline series.

2. An introduction to data structures with applications – Trembly & Sorenson.

Analog Communications Syllabus

2010-11-25T13:31:00.000+05:30

B.Tech. (ECE) V Semester

ANALOG COMMUNICATIONS

Course Code: EUREC503 Category: CE

Credits: 3 Hours: 3 per week

Department: ECE

UNIT-I

Linear Modulation Systems: Modulation, Frequency Translation, Amplitude modulation, AM equation, Modulation index, Spectrum of AM Signal, AM generation, AM detection, DSBSC- generation & detection, SSB- generation & detection, VSB – generation & detection, power relations, Applications of linear modulation systems, Frequency division multiplexing.

UNIT-II

Angle Modulation: Angle modulation, FM, FM Equation, modulation index, frequency deviation, NBFM, WBFM, Spectrum of FM, Bandwidth of FM, Carson’s rule, Phase modulation, Comparison of FM and PM, Generation of FM, Phasor representation of FM and AM, FM demodulation, Pre-emphasis and De-emphasis, power relations, stereophonic FM, Comparison of AM and FM.

UNIT-III

Noise: Sources of noise, thermal noise, shot noise flicker noise, white noise, mathematical representation of noise, power spectral density, effect of filtering on noise power spectral density, linear filtering, noise bandwidth, quadrature representation of noise and their power spectral density, noise figure, effective noise temperature, noise calculations for cascade stages.

UNIT-IV

Noise in AM and FM: Signal power, Noise power, Signal to noise ratio for DSBSC, SSB and FM, FM threshold effect.

UNIT-V

Radio Transmitters & Receivers: Classification of Radio Transmitters, AM Transmitters, FM Transmitters, Telegraph Transmitters, Telephone Transmitters, SSB Transmitters, Classification of Radio Receivers, TRF Receiver, Superhetrodyne Receiver, Characteristics of Superhetrodyne Receivers, Tracking, Importance of IF, Image Frequency Rejection, equation, Amplitude limiting, AGC, Delayed AGC, AFC.

Text Books:

1. Principles of communication H. Taub and Schilling McGraw Hill.

2. Communications Systems Simon Haykins, PHI.

References:

1. Electronic Communication Systems G. Kennedy, McGraw Hill.

2. Applied Electronics and Radio Engg. GK. Mithal

3. Modern Digital and Analog Communications Systems B. P. Lathi, BSP.

Linear Integrated Circuits Syllabus

2010-11-25T13:27:00.001+05:30

B.Tech. (ECE) V Semester

LINEAR ICs & APPLICATIONS

Course Code: EUREC502 Category: CE

Credits: 3 Hours: 3 per week

Department: ECE

UNIT-I

Operational Amplifiers: Concept of Direct Coupled Amplifiers. – Differential Amplifier - Calculation of common mode Rejection ratio – Differential Amplifier supplied with a constant current source – Normalized Transfer Characteristics of a differential Amplifier, Design Aspects of Monolithic Op-Amps, Ideal Characteristics of an operational Amplifier , Parameters of an Op-Amp, Measurement of Op-Amp Parameters, Frequency Compensation Techniques.

UNIT-II

Operational Amplifier Applications: Linear: Inverting and Non-inverting Amplifiers, Differential Amplifiers, Summing, scaling and Averaging amplifiers, Integrators, Differentiators, Logarithmic Amplifiers, Instrumentation Amplifiers, Voltage to Current and Current to Voltage Converters, Rectifiers, Peak Detectors.

Non-linear: Comparators, Schmitt trigger , Multivibrators, Sinewave oscillators (phase-shift, weinbridge, and Quadrature), Waveform generators (triangular and sawtooth) , Sample and Hold circuits, Analog multiplexers.

UNIT-III

Other Linear IC’s: 555 Timers – Monostable and Astable modes, 556 Function Generator ICs and their Applications. Three Terminal IC Regulators, IC 566 Voltage controlled oscillators, IC 565 PLL and its Applications.

UNIT-IV

A/D & D/A Converters: DAC characteristics D to A conversion process; multiplying DAC, 8 bit D to A converter, microprocessor compatibility, AD 558 Microprocessor Compatible DAC, serial DAC’s ADC characteristics A to D conversion process; successive approximation ADC microprocessor compatibility, ADC’s for microprocessors, AD 670 microprocessor compatible flash converters, frequency response of ADC’s.

UNIT-V

Active Filters: LPF, HPF, BPF, BEF, All-pass Filters, Higher Order Filters and their Comparison. Switched Capacitance Filters.

Text Books:

1. Op-Amps and Linear ICs, Ramakanth Gayakward, Pearson Education, LPE

2. Op-Amps and Linear Integrated Circuits by R.F Coughlin and F.F Driscoll by

Pearson Education, LPE, 6^th Ed.,

3. Operational amplifiers, George Clayton, Steve winder,Newnes,4^th edition

References:

1. Linear Integrated Circuits by S.Salivahanan,V.S.Kanchan Bhaskaran, TMH edition

2. Microelectronics, Jacob Millman and Arwin. W. Grasel, TMH edition

3. Linear Integrated Circuits, Roy Choudary and Vishal.K.Jain, New Age

4. Integrated electronics, Jacob Millman and Christos C. Halkias, MGH.

GATE 2011 Syllabus

2010-11-23T22:35:00.001+05:30

General Aptitude (GA)

Verbal Ability: English grammar, sentence completion, verbal analogies, word groups, instructions, critical reasoning and verbal deduction.

Numerical Ability: Numerical computation, numerical estimation, numerical reasoning and data interpretation.

Engineering Mathematics

Linear Algebra: Matrix Algebra, Systems of linear equations, Eigen values and eigen vectors.

Calculus: Mean value theorems, Theorems of integral calculus, Evaluation of definite and improper integrals, Partial Derivatives, Maxima and minima, Multiple integrals, Fourier series. Vector identities, Directional derivatives, Line, Surface and Volume integrals, Stokes, Gauss and Green’s theorems.

Differential equations: First order equation (linear and nonlinear), Higher order linear differential equations with constant coefficients, Method of variation of parameters, Cauchy’s and Euler’s equations, Initial and boundary value problems, Partial Differential Equations and variable separable method.

Complex variables: Analytic functions, Cauchy’s integral theorem and integral formula, Taylor’s and Laurent’ series, Residue theorem, solution integrals.

Probability and Statistics: Sampling theorems, Conditional probability, Mean, median, mode and standard deviation, Random variables, Discrete and continuous distributions, Poisson, Normal and Binomial distribution, Correlation and regression analysis.

Numerical Methods: Solutions of non-linear algebraic equations, single and multi-step methods for differential equations.

Transform Theory: Fourier transform, Laplace transform, Z-transform.

Electronics and Communication Engineering

Networks: Network graphs: matrices associated with graphs; incidence, fundamental cut set and fundamental circuit matrices. Solution methods: nodal and mesh analysis. Network theorems: superposition, Thevenin and Norton’s maximum power transfer, Wye-Delta transformation. Steady state sinusoidal analysis using phasors. Linear constant coefficient differential equations; time domain analysis of simple RLC circuits, Solution of network equations using Laplace transform: frequency domain analysis of RLC circuits. 2-port network parameters: driving point and transfer functions. State equations for networks.

Electronic Devices: Energy bands in silicon, intrinsic and extrinsic silicon. Carrier transport in silicon: diffusion current, drift current, mobility, and resistivity. Generation and recombination of carriers. p-n junction diode, Zener diode, tunnel diode, BJT, JFET, MOS capacitor, MOSFET, LED, p-I-n and avalanche photo diode, Basics of LASERs. Device technology: integrated circuits fabrication process, oxidation, diffusion, ion implantation, photolithography, n-tub, p-tub and twin-tub CMOS process.

Analog Circuits: Small Signal Equivalent circuits of diodes, BJTs, MOSFETs and analog CMOS. Simple diode circuits, clipping, clamping, rectifier. Biasing and bias stability of transistor and FET amplifiers. Amplifiers: single-and multi-stage, differential and operational, feedback, and power. Frequency response of amplifiers. Simple op-amp circuits. Filters. Sinusoidal oscillators; criterion for oscillation; single-transistor and op-amp configurations. Function generators and wave-shaping circuits, 555 Timers. Power supplies.

Digital circuits: Boolean algebra, minimization of Boolean functions; logic gates; digital IC families (DTL, TTL, ECL, MOS, CMOS). Combinatorial circuits: arithmetic circuits, code converters, multiplexers, decoders, PROMs and PLAs. Sequential circuits: latches and flip-flops, counters and shift-registers. Sample and hold circuits, ADCs, DACs. Semiconductor memories. Microprocessor(8085): architecture, programming, memory and I/O interfacing.

Signals and Systems: Definitions and properties of Laplace transform, continuous-time and discrete-time Fourier series, continuous-time and discrete-time Fourier Transform, DFT and FFT, z-transform. Sampling theorem. Linear Time-Invariant (LTI) Systems: definitions and properties; causality, stability, impulse response, convolution, poles and zeros, parallel and cascade structure, frequency response, group delay, phase delay. Signal transmission through LTI systems.

Control Systems: Basic control system components; block diagrammatic description, reduction of block diagrams. Open loop and closed loop (feedback) systems and stability analysis of these systems. Signal flow graphs and their use in determining transfer functions of systems; transient and steady state analysis of LTI control systems and frequency response. Tools and techniques for LTI control system analysis: root loci, Routh-Hurwitz criterion, Bode and Nyquist plots. Control system compensators: elements of lead and lag compensation, elements of Proportional-Integral-Derivative (PID) control. State variable representation and solution of state equation of LTI control systems.

Communications: Random signals and noise: probability, random variables, probability density function, autocorrelation, power spectral density. Analog communication systems: amplitude and angle modulation and demodulation systems, spectral analysis of these operations, superheterodyne receivers; elements of hardware, realizations of analog communication systems; signal-to-noise ratio (SNR) calculations for amplitude modulation (AM) and frequency modulation (FM) for low noise conditions. Fundamentals of information theory and channel capacity theorem. Digital communication systems: pulse code modulation (PCM), differential pulse code modulation (DPCM), digital modulation schemes: amplitude, phase and frequency shift keying schemes (ASK, PSK, FSK), matched filter receivers, bandwidth consideration and probability of error calculations for these schemes. Basics of TDMA, FDMA and CDMA and GSM.

Electromagnetics: Elements of vector calculus: divergence and curl; Gauss’ and Stokes’ theorems, Maxwell’s equations: differential and integral forms. Wave equation, Poynting vector. Plane waves: propagation through various media; reflection and refraction; phase and group velocity; skin depth. Transmission lines: characteristic impedance; impedance transformation; Smith chart; impedance matching; S parameters, pulse excitation. Waveguides: modes in rectangular waveguides; boundary conditions; cut-off frequencies; dispersion relations. Basics of propagation in dielectric waveguide and optical fibers. Basics of Antennas: Dipole antennas; radiation pattern; antenna gain.

DIFF. b/n MS nd M.TECH.

2010-11-23T22:33:00.001+05:30

Advantages of M.Tech:It is a guaranteed 2-years program. It is very difficult to delay your M.Tech. Some of the courses (subjects) are industry oriented. So, if you are looking to work in software industry, it might help. You have freedom to choose some percentage of courses.

Disadvantages of M.TechM.Tech is just a high-level B.Tech, where you take more advanced courses, do tougher assignments, do a better one-year project. Most often, such projects are not research-oriented. Therefore, the probability of getting a good offer for Ph.D admission after the M.Tech course is very less. If you are exceptionally good, and plan accordingly from the beginning of your M.Tech, this probability can be reduced considerably.You have to take around 10 courses. Depending on the courses, it might be a plus point or a negative point.

Now turning to M.S.

Advantages:You will be doing research. You will know what is research. You will know, whether you will like research or not.You will learn to read and follow research papers; you will learn to read papers in different ways.You can opt for a job or a PhD after the M.S. It is difficult to complete your M.S without publications; these publications will help you value your research potentials, and later, to get a good PhD admission offer.You can most often choose which all courses you want to credit (or attend).

Disadvantages:M.S course can take anywhere from 2 to 4 years. It depends a lot on your interactions with your guide. If you handle situations well, you might turn this to an opportunity, and learn to be calm and tough, mentally. But, it is not easy!

MBA

2010-11-23T22:32:00.003+05:30

MBA Courses

Among all the preferred career courses, Master of Business Administration or a post graduate diploma in management is perhaps the most sought after. The impact of privatization and liberalization has increased the need for managers in business establishments across all the sectors of the economy and those with an MBA degree from a reputed business school in India are the real beneficiaries of the changes brought by the globalization of India's market economy. Successful completion of an MBA course in India from a reputed institute promise a career that can touch unknown heights. A career in management, however, also demands great amount of dedication and good character. MBA Courses: MBA course curriculum in India can be categorized into the following 4 segments:

Full-time MBA

Part-time MBA

Distance Learning MBA

Executive MBA

Online MBA A full-time MBA usually comprises 4 semesters, inclusive of dissertation and project work, industrial exposure and summer internship. The students take up their respective major and minor specialization subjects. The choice of specialization subjects generally include: Marketing, Finance, Human Resources, Operations and Logistics, Information Technology, Systems, International Trade and Business, Consumer Behavior, Risk Management, and many others. However, executive MBA, part time MBA, distance learning MBA and even online MBA courses are increasingly becoming popular in India. While the part time, distance learning and online MBA courses offer flexibility to the students, executive MBA courses are meant exclusively for working professionals who are ready to take a break and like to obtain an MBA degree in a shorter time period than that of a full time course. MBA Admissions: Most of the leading Business Schools in India follow an admission process for screening applicants. The steps followed in the admission procedure are given below: Entrance Exam / The Written Test: Most MBA institutes in India have a written aptitude test. The IIMs conduct a Common Admission Test (CAT)every November. Many other business schools, like S.P. Jain Mumbai, MDI Gurgaon, and many others select students on the basis of their CAT score. Some other popular written tests for MBA in India conducted by other B-schools include: XAT, MAT, IIFT, SNAP, JMET, etc. Application Essays and Reference Letters: This step forms an integral part of the selection process of most top Indian B-schools. The short listed candidates of the IIMs and some other leading management institutes are expected to write these essays. GD / PI (Group Discussions / Personal Interviews): Group discussions and personal interviews are conducted generally to determine the personality traits and communication skills of the candidates. For many management colleges in India, Admission: Many B-schools offer admission to a candidate on the basis of the cumulative scores of the Entrance Exam, GD/PIs, and sometimes work experience. MBA Prospects in IndiaSuccessful completion of MBA courses can offer you at least the following options -

1)Fast-track growth in professional career

2)Being an entrepreneur, you can set up your own business

3)Opportunity to explore

4)Becoming a leader in an emerging field

5)Developing business knowledge and technical skills

Accept the MBA programme as a challenge by setting your personal and career objectives. Utilize the Masters of Business Administration degree for closing gaps lying within your skills and qualifications for advancing your management career. There is huge demand of talented and hard working people in the corporate sector these days. Your enthusiasm and hunger for success will surely make you amongst top entrepreneurs of the world.

GRE

2010-11-23T22:32:00.001+05:30

GRE Exam
GRE Exam is actually Graduate Recorded Exam. The Education Testing Service (ETS) directs The Graduate Record Examination (GRE) on behalf of the Graduate Record Examinations Board and the Council of Graduate Schools. GRE Exam chiefly a multiple-choice test. The GRE Exam scores have to be submitted by students aspiring for admission in international graduate school for Graduate program. Apart from the general GRE Exam there are about 12 GRE subject Tests offered by the program to help determine a students success in specific fields. In addition to this the GRE program also offers a variety of services and publications to help students transfer to their respective graduate program.
There are two versions of the GRE Exam, the first is the
GRE Exam - General
GRE Exam - Subject
The GRE Exam - General consists of three parts--
GRE verbal
GRE Math
GRE Essay
Both the GRE verbal and GRE math test in GRE Exam each yield a score between 200-800 points. Scores on the GRE analytical writing test are measured on a scale of 0 to 6 and is awarded in ï¿½ points. Since only some of the graduate programs require the scores of The GRE Exam - Subject, students availing such course need only appear for it.
The score on the GRE Subject test too ranges between 200 to 800 points. For details on the schools that need the GRE scoreand the minimum score that is required for admission can be found in the book, Graduate Study in Psychology,
GRE Exam - General Exam
The General GRE Exam consists of 3 sections, the
Verbal
Quantitative
Analytical writing sections.
The Analytical writing section is the latest addition. There are two versions of GRE Exam.
Paper Based GRE EXAM
Computer Based GRE EXAM The student is given the choice of taking GRE Exam on paper or on the computer. This section helps to determine the students writing and analyzing skills. There are two parts in this section that needs to be answered by the student. The first part has to be finished in 45 minute time limit. The student has to write an essay on the issue of a give topic. The second part deals with analysis of an argument and needs to be completed within 30 minutes. Of the 3 sections the writing test is the first to be taken.
Examples on topics of the Analytical section are available online on theGRE Online web page.
The student is allowed to take the GRE Exam only once in a month and a total of 5 times in one year period.
The unofficial GRE scores of the tests are available to the student as soon as the GRE Exam is completed.
The official GRE scores are sent to the student and to the institutions to which the student would be applying within 10 to 15 days after the GRE Exam.
The student can register for the GRE Exam online in the www.gre.org web site or by calling the 800 number given in the Information and Registration Bulletin.

projects

2010-11-20T22:06:00.001+05:30

www.8051projects.net

www.electronicsforu.com

New iPhone app could replace stethoscope

2010-09-12T09:39:00.001+05:30

London, Aug 31 (ANI): The standard equipment found with doctors, stethoscope, may soon be history as millions of doctors across the world are signing up for a free iphone app that can monitor heartbeat.

Peter Bentley of the University College London has invented the iStethoscope application, which monitors heartbeat through sensors in the phone.

As many as 500 apps are being downloaded everyday since a free version was introduced last week. Everybody is very excited about the potential of the adoption of mobile phone technology into the medical workplace, and rightly so," the Telegraph quoted Bentley as saying.

"Smartphones are incredibly powerful devices packed full of sensors, cameras, high-quality microphones with amazing displays," he added. (ANI)

Working of Amplifier

2010-04-10T19:11:00.004+05:30

What is an Amplifier?
We see amplifiers in almost all the electronic equipments around us. Though we usually relate them to stereo equipments they are also found in TV’s, computers, MP3 players and so on. All these devices have a speaker which is used to reproduce the original sound.

Therefore an amplifier can be device that is used to change the amplitude of a signal. This increase in amplitude can be calculated by a factor known as transfer function, which is actually the ratio between the output and input given to the amplifier. The magnitude of this transfer function is called the gain of the amplifier.

When referring to electronic circuits, the signal used in an amplifier is mostly either current or voltage. A sound is said to be amplified, when the device makes the sound louder than usual with the same clarity. The amplifiers are divided according to the source that is supposed to be amplified, the driving device, the frequency of the signal and the type of signal.

The source can be an electric guitar and the driving device can be a head-phone amplifier. The frequency of the signal is defined in its range like audio, IF, RF, VHF and so on. The type of signal refers to two parameters – inverting and non-inverting. Another major classification is in the device that is used to design the amplifiers. The most commonly used devices are Field-Effect transistors, and valve.

Role of an Amplifier
The amplification process is similar to the way in which the human receives the sound from our surrounding. When a voice is made it starts to vibrate in the atmosphere, thus beginning to move the air particles in hits. This causes more air particles to be hit and thus creates a vibrating pulse in the air. When it reaches our ears, they will be received as an air pressure and will be converted to the appropriate signals by our brain. We can define the working of amplifiers in the same sense.

Sound waves will be sent through a microphone. The diaphragm of the microphone moves it in a peculiar motion and converts it into electrical signals. This fluctuating electric signal will be represented as compressions and rarefactions of the original sound.

The electric signal will be encoded by the recorder and stored in a tape, CD and so on.

A player for the particular recorded signal interprets the electrical signal and is given to the speaker which turns the cone back and forth. The same variation in pressure will be reproduced by the speaker as it was in the beginning. The basic block diagram of an amlifier is given below.

How Amplifiers Work
From the above method you must have understood that translators play a major role in the working. That is, from a sound signal to electrical signal and vice versa. The main translators here are the microphone and the speaker. The microphone diaphragm has to be designed in a careful manner so as to make it highly sensitive to even the smallest pressure variations the sound produced. Thus, its design will be slim in nature and will produce a small electric current as it can move only a very small distance. The design of the other translator, the speaker is a little more difficult. The cone of it has to move backwards and frontwards and for this you need its input signal to be high so that it maintains a large current so as to keep the manner of charge fluctuation constant. This role can only be done by the amplifier. That is, the weak electric signal from the microphone has to be amplified by the amplifier before producing it to the cone of the speaker.

Basic Elements of an Amplifier
Though the basic explanation of an amplifier was explained above, the making of it is far more complex. We know that there are two signals generated during the process. They are the input signal and the output signal. The input signal is completely different from the output signal. Thus we can consider the generation of these signals as two separate electronic circuits. The input signal circuit is the signal recorded in a tape. It is designed as to modify the output signal circuit with its load. This is done by changing the resistance to the output circuit so as to make new voltage fluctuations of the original sound signal. But this load is very high when compared to the original sound. So, the sound must be first boosted with the help of a pre-amplifier. This will help in making a much more strong output signal as the input to the power amplifier. There is no much difference in the working of pre-amplifier compared to amplifier. A change in resistance is given by the input circuit to the output circuit, through the power supply. The design and number of pre-amplifiers in an amplifier varies according to the manufacturer.

The output circuit is generated by the power supply of the amplifier. The power supply helps in drawing the required energy from an external battery or power outlet.

Mostly the main power supply will be in ac form. It will be changed to dc and then given to the amplifier. The power supply also helps in making an uninterrupted signal by making the current smoother. This load will then be given to the cone of the speaker.

For all this to work together a combination of many electronic circuits will be needed. The designer has to make sure that each and every part of the audio signal is correctly represented.

Basic Components of an Amplifier
One of the most basic components of an amplifier circuit is the transistor. The materials of the components used for an amplifier, must be able to conduct electric current in a varying manner. That is why the transistor is often used. The working of an N-P-N transistor is given below.

We know that N-type semiconductors carry electrons and P-type semiconductors carry holes. In an N-P-N transistor, the P-type semiconductor will be kept in between two N-type semiconductors. This is illustrated below.

Working of transistor in an Amplifier
From the left, the first N-type semiconductor is called the emitter. The middle P-type semiconductor is called the base and the end N-type semiconductor is called the collector. The output circuit which is supposed to drive the speaker is connected between the collector and the emitter ends. The input circuit will be connected between the emitter and the base terminals.

The N-type electrons and the P-type holes start to get attracted. But, the number of free electrons is way higher than the number of holes. This will result in the combination and the filling up of holes. As a result of this combination depletion holes will be created at the boundaries of the N-type and P-type. This will cause the semiconductor material to switch back to its insulating state. Thus the charges get accumulated with no other place to go. Thus the depletion zones get heavier. Thus the movement of charge from the emitter to the collector reduces, even if there is a huge difference in voltage between the two electrodes. This situation has to be overcome.

For the problem to be solved, a high voltage supply must be given to the base terminal. As the input current controls the base terminal its flow will cause the base terminal to have a higher positive charge and thus attracts the electrons from the emitter terminal. This in turn reduces some holes and thus reduces the size of the depletion region. This will help in an easier movement of the charges from the emitter to the collector. All these actions cause a natural increase in the conductivity of the transistor.

In short, the voltage given to the base terminal decides the amount of conductivity of the transistor and the size of the depletion region. Here is the diagram of the working of a transistor as an amplifier.

Working of Amplifiers-Step 1

Working of Amplifiers-Step 2

Working of Amplifiers-Step 3

Working of Amplifiers-Step 4
The above shown figure is just one stage of an amplifier. In order to get the sound signal boosted up in the form of an electrical signal, there has to be a lot more stages. Anyhow, the final stage of amplification will be the speaker driver.

The output power produced in an amplifier depends on the necessity of its use. If it is used in some huge hall, the amplifier must produce an output power of at least a thousand watts. On the other hand, if it is used in a home theatre stereo amplifier, it may just need a few hundreds of watts as the output power. If it is in a speaker phone, the output will be the least of half a watt.

Whatever the power may be, an amplifier must produce the least amount of distortion as possible. On the same time, the boosting of the sound must be high in the final driving stage and a high replica of the original sound must be produced. For these characteristics to occur accurately, the parameters like power rating, input impedance, output impedance and also fidelity must be varied accurately.

By the concept of amplifiers we always think of amplifying sound. But, the same process can be done for amplifying radio signals and video signals as well.

High-power UV LEDs target UV-curing for industrial apps

2010-04-06T08:32:00.002+05:30

I’ve seen UV disinfecting wands at Costco and wondered why they don’t use HB LEDs as their UV source. HB LEDs are more rugged and can be a more compact light source than lamps. What gives?

It turns out that to act as a disinfecting energy, UV radiation needs wavelengths in the 250nm range, and it’s very hard to make LEDs in that wavelength. Where UV LEDs are coming on strong, though, is for UV curing at 390 nm in industrial processes using UV-cured epoxies, inks, paints, laminates and adhesives. This is the market Luminus is targeting with its new UV CBT-120. UV curing requires lots of UV photons, and Luminus’s PhlatLight technology excels as a large-area LED light source. The UV CBT-120 has a power density of 1 W/mm²with a light energy output of 10W at 390 nm.

Apple ipad Day arrives

2010-04-06T08:24:00.001+05:30

Chipworks is not normally in the business of blogging teardowns, we leave that to the guys at iFixit and PowerbookMedic, but after my previous speculation on an NXP chip being present next to Apple’s A4 processor chip, I thought it worth confirming. We got our sample this afternoon, and long weekend or not, our guys are in the lab pulling it apart. So first let’s look at the board:

Apple iPad Main Board Topside

Aside from the A4 chip, there are a couple of Samsung 64Gbit NAND flash parts, and next to the screen connectors, a duo of Broadcom parts (BCM 5973 and 5974) and a TI CD3240A. If we zoom in on the A4 we can indeed see that NXP got a design win - somewhat mysteriously marked L0614, it’s adjacent to the connector to the WiFi chip and the connector dock.

Close-up of the A4 Processor and NXP Chip

A bit of searching of the NXP site comes up with the CBLT06141 mux/demux part for DisplayPort and PCIe connections. My other speculation about the A4 was that it didn’t look like the Package-on-Package (PoP) structure used in the iPhones and iPod Touch. Turns out I was wrong - the K4X2G643GE marking on the package indicates the incorporation of 2Gbits of Samsung mobile DDR SDRAM. Whether it’s 2 x 1Gb or 1 x 2Gb chips in there we’ll see when we decapsulate the part. It’s possible it’s a multi-chip package, but it’s more likely PoP since this conformation gives Apple the flexibility to multisource the DRAM.

As an example, below is a package cross-section of the PoP out of the iPhone 3GS (click on the thumbnail image). This also had 2Gb of DRAM within, in the top part of the PoP. In this case the DRAM chips were sourced from Elpida, and the bondpad layout was such that all the bond wires are on one edge of the chip, so the two dies are offset to allow bonding. Another version of the PoP uses Samsung DRAM, with the bonds laid out at both ends of the die, so a different bonding set-up has to be used.

We’ll find out what’s in the A4 in the next few days - stay tuned! There will also be more details on the Chipworks website as our guys get into the iPad internals

BLUETOOTH

2009-07-26T01:12:00.000+05:30

Bluetooth is an open wireless protocol for exchanging data over short distances from fixed and mobile devices, creating personal area networks (PANs). It was originally conceived as a wireless alternative to RS232 data cables. It can connect several devices, overcoming problems of synchronization