1. What are Flip flops and explain their working?In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic. The word latch is mainly used for storage elements, while clocked devices are described as flip-flops.Memory relies on a concept called feedback. That is, the output of a gate is fed back into the input.

2. What is a FSM?A finite-state machine (FSM) or finite-state automaton (plural: automata), or simply a state machine, is a mathematical model used to design computer programs and digital logic circuits. It is conceived as an abstract machine that can be in one of a finite number of states. The machine is in only one state at a time; the state it is in at any given time is called thecurrent state. It can change from one state to another when initiated by a triggering event or condition, this is called a transition.

3. What is totem pole output?A type of output structure used with integrated circuits in which one transistor drives the output high while another transistor connected below it pulls the output low.

4. What is the mode of transmission of TV signals?There are basically two methods of up-linking signals to an orbital satellite. The C-band and the Ku-band mode. In both cases the signal transmitted are in the radio wave region of the electromagnetic Spectrum.C Band: 5.925-6.425 GHz Ku Band: 14.0-14.5 GHz

5. Draw the internal circuit of 8085 microprocessor.

6. What is a bit? In computing, a bit can also be defined as a variable or computed quantity that can have only two possible values. These two values are often interpreted asbinary digits and are usually denoted by the Arabic numerical digits 0 and 1.

7. What is CMOS?Complementary metal–oxide–semiconductor (CMOS) is a technology for constructing integrated circuits. CMOS technology is used in microprocessors, microcontrollers, static RAM, and other digital logic circuits. Frank Wanlass patented CMOS in 1967.CMOS circuits use a combination of p-type and n-type metal–oxide–semiconductor field-effect transistors (MOSFETs) to implement logic gates and other digital circuits found incomputers, telecommunications equipment, and signal processing equipment.

8. What is the bandwidth of FM and AM radio?FM refers to frequency modulation, and occurs on VHF airwaves in the frequency range of 88 to 108 MHz everywhere (except Japan andRussia). FM radio was invented by Edwin H. Armstrong in the 1930s for the specific purpose of overcoming the interference problem of AM radio, to which it is relatively immune.AM radio is broadcast on several frequency bands:1. Long wave is 148.5 kHz–283.5 kHz2. Medium wave is 520 kHz–1,610 kHz3. Short wave is 2.3 MHz–26.1 MHz

9. What is Carson’s Bandwidth Rule?In telecommunication, Carson's bandwidth rule defines the approximate bandwidth requirements of communications system components for a carrier signal that is frequency modulated by a continuous or broad spectrum of frequencies rather than a single frequency. Carson's bandwidth rule is expressed by the relation CBR = 2(Δf + fm) where CBR is the bandwidth requirement, Δf is the peak frequency deviation, and fm is the highest frequency in the modulating signal.

10.As an electronics engineer, how would you distinguish between paper money and digital money?In technical terms, electronic money is an online representation, or a system of debits and credits, used to exchange value within another system, or within itself as a stand alone system. In principle this process could also be done offline.Electronic money (also known as e-currency, e-money, electronic cash, electronic currency, digital money, digital cash, digital currency, cyber currency) is money or scrip that is only exchanged electronically. Typically, this involves the use of computer networks, the internet and digital stored value systems. electronic funds transfer (EFT), direct deposit,digital gold currency and virtual currency are all examples of electronic money. Also, it is a collective term for financial cryptography and technologies enabling it.

11.What is modem? Draw its internal diagram.A modem (modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data.

12.Obtain a square wave from a sine wave using Zener diodes.

The circuit works as a classical inverting amplifier except that the voltage amplitude is limited to the Zener diode voltages. The maximum amplitude level cannot exceed the sum of the Zener diode OFF voltage (vz) and the

Zener diode ON voltage (vf). We can set the slope of the linear region (with properly chosen R2 and R1 values) and the saturation level (changing the Zener diode) as well.

13.What is difference between oscillator and multivibrator?Oscillators and multivibrators are electronic circuits that produce repeating signals. An oscillator produces sine waves and a multivibrator does not. Oscillator and multivibrator designs take different approaches to signal generation. The oscillator uses a resonant circuit and amplifier and the multivibrator is based on an electronic switch.Oscillator:A bell resonates at a natural frequency. If you ring it, it produces a tone that fades away. An oscillator "rings" a special circuit that creates a signal at a specific frequency. An electronic amplifier sustains the signal, keeping it from dying out. The amplifier has its output connected to its input with the resonant circuit in the path. These circuits produce sine wave signals. Multivibrator: When the circuit has low current, the switch turns on, sending charge to a capacitor. When the capacitor's charge reaches a certain level, the switch turns off and discharges the capacitor. The low current in the circuit turns the switch on again, repeating the cycle. This is an astable multivibrator, as it continually switches itself on and off. A bistable multivibrator remains either on or off after you switch it.

14.What is blue tooth and WAP?Wireless Application Protocol (WAP) is a technical standard for accessing information over a mobile wireless network. Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances (using short wavelength radio transmissions in the ISM band from 2400-2480 MHz) from fixed and mobile devices, creating personal area networks (PANs) with high levels of security. Created by telecoms vendor Ericsson in 1994,[1] it was originally conceived as a wireless alternative to RS-232 data cables. It can connect several devices, overcoming problems of synchronization.

15.What is IMPATT and TRAPATT diode?IMPATT: A pn junction diode that has a depletion region adjacent to the junction, through which electrons and holes can drift, and is biased beyond the avalanche breakdown voltage. Derived from impact avalanche and transit time diode.TRAPATT: A pnjunction diode, similar to the IMPATT diode, but characterized by the formation of a trapped space-charge plasma within the junction region; used in the generation and amplification of microwave power. Derived from trapped plasma avalanche transit time diode.

16.What is emitter follower?In electronics, a common-collector amplifier (also known as an emitter follower or BJT voltage follower) is one of three basic single-stage bipolar junction transistor (BJT) amplifier topologies, typically used as a voltage buffer. In this circuit the base terminal of the transistor serves as the input, the emitter is the output, and the collector is common to both (for example, it may be tied to ground reference or a power supply rail), hence its name. 

17.What is voltage buffer amplifier?A voltage buffer amplifier is used to transfer a voltage from a first circuit, having a high output impedance level, to a second circuit with a low input

impedance level.

18.Write Maxwell equations.

19.What is electromagnetic wave equation?The electromagnetic wave equation is a second-order partial differential equation that describes the propagation of electromagnetic waves through a medium or in a vacuum. Thehomogeneous form of the equation, written in terms of either the electric field E or the magnetic field B, takes the form:

Where

20.What happens when you type user-name and password while logging on to a Unix system?Once you have successfully logged in, you get all the privileges associated with the individual account you are using. You may also be recognized as part of a group. A group is a named collection of users set up by the system administrator. Groups can have privileges independently of their members’ privileges. A user can be a member of multiple groups. Your account entry also contains your home directory, the place in the Unix file system where your personal files will live. Finally, your account entry also sets your shell, the command interpreter that login will start up to accept your commmands.

21.Draw the circuit for an adder using NAND gates.

22.Define Control System. What are the different types of control systems?A control system is a device, or set of devices to manage, command, direct or regulate the behavior of other devices or system. There are two common classes of control systems, with many variations and combinations: logic or sequential control and feedback or linear controls. In order to define more precisely control systems, one can separate them into two different categories:The open-loop Control Systems (nonfeedback systems)

The closed-loop Control Systems (feedback is used in part of the input given to the control system /controller)

Closed-loop controllers have the following advantages over open-loop controllers:

disturbance rejection (such as unmeasured friction in a motor) guaranteed performance even with model uncertainties, when the model

structure does not match perfectly the real process and the model parameters are not exact

unstable  processes can be stabilized reduced sensitivity to parameter variations improved reference tracking performance

Digital control systems are commonly separated into two classes:The signal in a sampled-data control system is in the form of pulse data. On the other hand, when a digital computer or controller is used in a control system, it is referred to as a Digital Control System.  

23.What are the different stable control system criterion?For a causal linear system to be stable all of the poles of its transfer function must satisfy some criteria depending on whether a continuous or discrete time analysis is used:In continuous time, the Laplace transform is used to obtain the transfer function. A system is stable if the poles of this transfer function lie strictly in the open left half of the complex plane (i.e. the real part of all the poles is less than zero).In discrete time the Z-transform is used. A system is stable if the poles of this transfer function lie strictly inside the unit circle. i.e. the magnitude of the poles is less than one).

NYQUIST STABILITY CRITERIA: Given a Nyquist contour Γs, let P be the number of poles of G(s) encircled by Γs, and Z be the number of zeros of 1 + G(s) encircled by Γs. Alternatively, and more importantly, Z is the number of poles of the closed loop system in the right half plane. The resultant contour in the G(s)-plane, ΓG(s) shall encircle (clock-wise) the point ( − 1 + j0) N times such thatN = Z − P.

BHARK HAUSEN CRITERIA: It states that if   is the gain of the amplifying element in the circuit and   is the transfer function of the feedback path, so   is the loop gain around the feedback loop of the circuit, the circuit will sustain steady-state oscillations only at frequencies for which:

The loop gain is equal to unity in absolute magnitude, that is,  There must be a positive feedback i.e., the phase shift around the loop is

zero or an integer multiple of 2π: 

The Barkhausen stability criterion is a mathematical condition to determine when a linear electronic circuit will oscillate. 

ROUTH HERWITZ CRITERIA: f(z) is Hurwitz-stable iff p − q = n. We thus obtain conditions on the coefficients of f(z) by imposingw(+∞) = n and w(−∞) = 0.p is the number of roots of the polynomial ƒ(z) with negative Real Part;q is the number of roots of the polynomial ƒ(z) with positive Real Part (let us remind ourselves that ƒ is supposed to have no roots lying on the imaginary line);w(x) is the number of variations of the generalized Sturm chain obtained from P0(y) and P1(y) (by successive Euclidean divisions) 

24.What are poles and zeroes?It is often convenient to factor the polynomials in the numerator and denominator, and to write the transfer function in terms of those factors:H(s) =N(s)/D(s) The roots of N(s)=0 are called zeroesThe roots of D(s)=0 are called polesThe poles and zeros are properties of the transfer function, and therefore of the differential equation describing the input-output system dynamics. Together with the gain constant K they completely characterize the differential equation, and provide a complete description of the system.The zeros of the transfer function simply represent the places (frequencies) where the system has a gain of zero. (Thus, these frequencies will be totally cut out of the signal.)The poles of the transfer function represent places (frequencies) where the system has an infinite gain. (Thus, these frequencies will send the system into resonance with zero damping.)

25.What is Karnaugh map?The Karnaugh map (K-map for short), Maurice Karnaugh's 1953 refinement of Edward Veitch's 1952 Veitch diagram, is a method to simplifyBoolean algebra expressions. The Karnaugh map reduces the need for extensive calculations by taking advantage of humans' pattern-recognition capability, also permitting the rapid identification and

elimination of potential race conditions.In a Karnaugh map the boolean variables are transferred (generally from a truth table) and ordered according to the principles of Gray code in which only one variable changes in between adjacent squares. Once the table is generated and the output possibilities are transcribed, the data is arranged into the largest possible groups containing 2n cells (n=0,1,2,3...)[1] and the minterm is generated through the axiom laws of boolean algebra.

26.Draw 8086 internal architecture.

27.What is a Bus? Explain different types of buses.Buses All of the basic components of the computer are tied together by communications paths called buses. A computer bus is simply a parallel collection of conductors that carry data and control signals from one unit

to another.Types of BusesAny computer has three major system buses identified by the type of information they carry. The three major system buses are: Address bus, Data bus, Control bus.Address Bus The address bus is a unidirectional pathway that carries addresses generated by the microprocessor to the memory and I/O elements of the computerData Bus In contrast to the address bus, the data bus is bi-directional in nature. Data flows along the data bus from the microprocessor to memory during a Write operation. Conversely, data moves from memory to the microprocessor during a Read operation. The direction for data movement is the same for Read and Write operations between the microprocessor and Input/Output devices.Control Bus The control bus carries the timing and control signals necessary to coordinate the activities of the entire system.

28.What is a Register? Explain different types of registers.In computer architecture, a processor register is a small amount of storage available as part of a CPU or other digital processor. Such registers are (typically) addressed by mechanisms other than main memory and can be accessed more quickly.Types:Accumulator: It is nothing but a register which can hold 8-bit data. Accumulator aids in storing two quantities.The data to be processed by arithmetic and logic unit is stored in accumulator.It also stores the result of the operation carried out by the Arithmetic and Logic unit.General purpose registers: They are used to hold data like any other registers. The general purpose registers in 8085 processors are B, C, D, E, H and L. Each register can hold 8-bit data. Apart from the above function these registers can also be used to work in pairs to hold 16-bit dataProgram counter : It is a special purpose register(16 bit).  The program counter keeps track of the memory address of the instructions that are being executed by the microprocessor and the memory address of the next instruction that is going to be executed.Stack pointer is also a 16-bit register which is used as a memory pointer. A stack is nothing but the portion of RAM (Random access memory). Stack pointer maintains the address of the last byte that is entered into stack.Temporary Register: This register acts as a temporary memory during the arithmetic and logical operations. Unlike other registers, this temporary register can only be accessed by the microprocessor and it is completely inaccessible to programmers.(8bit)

29.What is segment register?Base registers or segment registers are used to segment memory. Effective addresses are computed by adding the contents of the base or segment register to the rest of the effective address computation.

30. Which is the 1st 32-bit microprocessor?The world's first single-chip fully 32-bit microprocessor, with 32-bit data paths, 32-bit buses, and 32-bit addresses, was the AT&T Bell Labs BELLMAC-32A, with first samples in 1980, and general production in 1982.

31.What are the different types of UPS?• Standby • Line Interactive • Standby-Ferro • Double Conversion On-Line • Delta Conversion On-Line

32.What is the difference between 8086 and 80286?The 8086/8088 is a 16 bit processor running on a 16 bit (8086) or 8 bit (8088) bus with a 20 bit address. It can address 1 MB of memory. The 80286 is a 16 bit processor running on a 16 bit bus with a 24 bit address. It can address 16mb of memory. As the meaning of the segment register changed, the 80286 was not object code compatible with programs written for the 8086/8088. This is one of the factors that made the 80286 unpopular.

33.What is antenna? What is its principle of working?An antenna (or aerial) is an electrical device which converts electric currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio receiver.Typically an antenna consists of an arrangement of metallic conductors ("elements"), electrically connected (often through a transmission line) to the receiver or transmitter. An oscillating current of electrons forced through the antenna by a transmitter will create an oscillating magnetic field around the antenna elements, while the charge of the electrons also creates an oscillating electric field along the elements. These time-varying fields radiate away from the antenna into space as a moving electromagnetic field wave. Conversely, during reception, the oscillating electric and magnetic fields of an incoming radio wave exert force on the electrons in the antenna elements, causing them to move back and forth, creating oscillating currents in the antenna.

34.What is ROC? Receiver operating characteristic (ROC), or simply ROC curve, is a graphical plot of the sensitivity, or true positive rate, vs. false positive rate (1 − specificity or 1 − true negative rate), for a binary classifier system as its discrimination threshold is varied.  ROC analysis is related in a direct and natural way to cost/benefit analysis of diagnostic decision making.

35.What is bitrate?In telecommunications and computing, bit rate (sometimes written bitrate, data rate or as a variable R[1]) is the number of bits that are conveyed or processed per unit of time

36.What is the difference between .wav .mp3 and .mp4?An older music format, WAV was designed by Microsoft to play short snippets of sound on any audio-enabled computer. MP3 stands for MPEG-1 Audio Layer 3. The MPEG process compresses a sound sequence into a very small file, while retaining its original quality by being very selective and eliminating certain sound frequencies that can't be heard by the human ear. The format compresses the file to approximately 1/12 the size of the original file, making it quicker to download or share with a friend.MP4 is short for MPEG-4 Part 14.  MP4 is based on MPEG-4 Part 12 which was in turn based on Apple’s MOV file type.  MP4 is a container format, meaning it is used to store audio and/or video data, rather than to code the information.  MP4 video and audio can also be streamed over the internet.  This is also true of most other modern container formats.

37.What is sampling?In signal processing, sampling is the reduction of a continuous signal to a discrete signal. A common example is the conversion of a sound wave (a continuous signal) to a sequence of samples (a discrete-time signal).A sample refers to a value or set of values at a point in time and/or space.A sampler is a subsystem or operation that extracts samples from a continuous signal.

38.What is plugin?In computing, a plug-in (or plugin) is a set of software components that adds specific abilities to a largersoftware application. If supported, plug-ins enable customizing the functionality of an application. 

39.Explain the functioning of Op-Amp.An operational amplifier ("op-amp") is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output.[1] An op-amp produces an output voltage that is typically hundreds of thousands times larger than the voltage difference between its input terminals.

40.What do you mean by 20-bit address bus?20-bit address bus (e.g. Intel 8086) can address 220 (1,048,576) memory locations.

41.What do you mean by database?A database is an organized collection of data for one or more purposes, usually in digital form.Lotus Approach is a relational database management system included in IBM's Lotus SmartSuite for Microsoft Windows.

42.What is circuit switching and packet switching?Circuit switching is a methodology of implementing a telecommunications network in which two network nodes establish a dedicated communications channel (circuit) through the network before the nodes may communicate. The circuit guarantees the full bandwidth of the channel and remains connected for the duration of the communication session. The circuit functions as if the nodes were physically connected as with an electrical circuit.Packet switching is a digital networking communications method that groups all transmitted data – regardless of content, type, or structure – into suitably sized blocks, called packets. Packet switching features delivery of variable-bit-rate data streams (sequences of packets) over a shared network. When traversing network adapters, switches, routers and other network nodes, packets are buffered and queued, resulting in variable delay and throughput depending on the traffic load in the network.

43.What is the difference between half adder and full adder?Full adder accepts three one bit and generates a sum and carry out. Whereas half adder as accepts only two one bit to generate sum and carry.

44.What is VOIP?Voice over IP (VoIP) is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet.Other terms frequently encountered and often used synonymously with VoIP are IP telephony, Internet telephony,voice over broadband (VoBB), broadband telephony, and broadband phone.

45.What are the types of digital communication ?

46.What is an electronic amplifier? What are its different classes?An electronic amplifier is a device for increasing the power of a signal.It does this by taking energy from a power supply and controlling the output to match the input signal shape but with a larger amplitude. In this sense, an amplifier may be considered as modulating the output of the power supply.CLASSES OF POWER AMPLIFIERS:Power amplifier circuits (output stages) are classified as A, B, AB and C for analog designs, and class D and E for switching designs based upon the conduction angle or angle of flow, Θ, of the input signal through the (or each) output amplifying device, that is, the portion of the input signal cycle during which the amplifying device conducts. Class A: 100% of the input signal is used (conduction angle Θ = 360° or 2π); i.e., the active element remains conducting[6] (works in its "linear" range) all of the time.Class B: 50% of the input signal is used (Θ = 180° or π; i.e., the active element works in its linear range half of the time and is more or less turned off for the other half).Class AB: Here the two active elements conduct more than half of the time as a means to reduce the cross-over distortions of class-B amplifiers.ClassC: Less than 50% of the input signal is used (conduction angle Θ < 180°). The advantage is potentially high efficiency, but a disadvantage is high distortion.Class D: These use switching to achieve a very high power efficiency (more than 90% in modern designs).

47.What is a DMA controller?Direct memory access (DMA) is a feature of modern computers that allows certain hardware subsystems within the computer to access system memory independently of the central processing unit (CPU).

48.Which is the universal flip flop?JK Flip Flop.

49.What are interrupts? How will you set an interrupt?In computing, an interrupt is an asynchronous signal indicating the need for attention or a synchronous event in software indicating the need for a change in execution.Maskable interrupt (IRQ) is a hardware interrupt that may be ignored by setting a bit in an interrupt mask register's (IMR) bit-mask.Non-maskable interrupt(NMI) is a hardware interrupt that lacks an associated bit-mask, so that it can never be ignored. NMIs are often used

for timers, especially watchdog timers.Inter-processor interrupt(IPI) is a special case of interrupt that is generated by one processor to interrupt another processor in a multiprocessor system.Software interrupt is an interrupt generated within a processor by executing an instruction. Software interrupts are often used to implement system calls because they implement a subroutine call with a CPU ring level change.Spurious interrupt is a hardware interrupt that is unwanted. They are typically generated by system conditions such as electrical interference on an interrupt line or through incorrectly designed hardware. An act of interrupting is referred to as an interrupt request (IRQ).

50.Compare SRAM and DRAM.DRAM requires the data to be refreshed periodically in order to retain the data. SRAM does not need to be refreshed as the transistors inside would continue to hold the data as long as the power supply is not cut off.The additional circuitry and timing needed to introduce the refresh creates some complications that makes DRAM memory slower and less desirable than SRAM.Structurally, SRAM needs a lot more transistors in order to store a certain amount of memory. A DRAM module only needs a transistor and a capacitor for every bit of data where SRAM needs 6 transistors. Because the number of transistors in a memory module determines its capacity, a DRAM module can have almost 6 times more capacity with a similar transistor count to an SRAM module. Because of its lower price, DRAM has become the mainstream in computer main memory despite being slower and more power hungry compared to SRAM.Cheaper DRAM is used in main memory while SRAM is commonly used in cache memory.

51.What are the advantages of CMOS over TTL:

1. Operates on a wider supply voltage (2 to 15 volts).Exception is 74HC CMOS limited to (2 to 7 volts).2. Uses much less power, can operate on a small battery for a year orso.3. Output swings the full supply voltage range.4. Input switches at half the supply voltage for better noise immunity.5. Input impedance is much higher so it doesn't load the drivingcircuit.6. 74HC CMOS can supply 25mA of output current, both source and sink.

52.What are the different IC types on the basis of no. Of components?

53.What is prime implicant?A prime implicant of a function is an implicant that cannot be covered by a more general (more reduced - meaning with fewer literals) implicant. W.V. Quine defined a prime implicant ofF to be an implicant that is minimal - that is, if the removal of any literal from P results in a non-implicant for F. 

54.What is compiler?A compiler is a computer program (or set of programs) that transforms source code written in a programming language(the source language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program. The name "compiler" is primarily used for programs that translate source code from a high-level programming languageto a lower level language (e.g., assembly language or machine code).

55.What is VHDL?VHDL (VHSIC hardware description language) is a hardware description language used in electronic design automation to describedigital and mixed-signal systems such as field-programmable gate arrays and integrated circuits.

56.Explain half-duplex and full-duplex communication?

A duplex communication system is a system composed of two connected parties or devices that can communicate with one another in both directions. (The term multiplexing is used when describing communication between more than two parties or devices.)Duplex systems are employed in many communications networks, either to allow for a communication

"two-way street" between two connected parties or to provide a "reverse path" for the monitoring and remote adjustment of equipment in the field.A half-duplex (HDX) system provides communication in both directions, but only one direction at a time (not simultaneously). E.g. Walkie TalkieA full-duplex (FDX), or sometimes double-duplex system, allows communication in both directions, and, unlike half-duplex, allows this to happen simultaneously. Land-line telephone networks are full-duplex.

57.Which range of signals are used for terrestrial transmission?VHF(30MHZ-300MHZ)

58.Why is there need for modulation?

59.Modulation used in TV transmission?All analog television systems use vestigial sideband modulation, a form of amplitude modulation in which one sideband is partially removed. This reduces the bandwidth of the transmitted signal, enabling narrower channels to be used.

60.When transmitting digital signals is it necessary to transmit some harmonics in addition to fundamental frequency?

61.For asynchronous transmission, is it necessary to supply some synchronizing pulses additionally or to supply or to supply start and stop bit?An asynchronous transmission sends no characters over the interconnection when the transmitting device has nothing to send. Yes, it is necessary. Otherwise the receiver will not be able to detect the starting or the ending of a byte sent by receiver. And in Asynchronous transmission it is not the responsibility of the receiver to group the bits sent by sender.

62.BPFSK is more efficient than BFSK in presence of noise. Why?Actually, BPSK is not susceptible to the noise degradation that affects ASK or bandwidth limitations of BFSK ( BFSK needs more bandwidth than BPSK) . This

means that smaller variations in the BPSK signal due to noise can be detected reliably.

63..What is meant by pre-emphasis and de-emphasis?1.Pre-emphasis: - Improving the signal to noise ratio by increasing the magnitude of higher frequency signals with respect to lower frequency signals.2.De-emphasis: - It is the complement of pre-emphasis, in the antinoise system called emphasis. Improving the signal to noise ratio by decreasing the magnitude of higher frequency signals with respect to lower frequency signals.

64.What do you mean by 3 dB cutoff frequency? Why is it 3 dB, not 1 dB?In case of frequency response of active filters, Cut off frequency is referred to that limiting frequency after which the gain decreases @20dB/decade.We - know, gain (in dB) =20log|Vo/Vin|, where |Vo/Vin| = AF/sqrt(1+(F/FH)^2). Now, at F=FH, |Vo/Vin| =AF/sqrt2 = 0.707AF. Now, if we consider thepassband gain i.e. AF = 1, then the gain at cutoff frequency will be = 20log (0.707) = 3dB.That is why it is always called 3dB cut offfrequency, not 1dB.In addition, 3db implies 70% (0.707) of the power, i.e. we r interested to consider the bandwidth range from peak to 70% because up to 70% it’s reliable. Hence 3db is called the half power frequency.

65.What do you mean by ASCII, EBCDIC?1.ASCII: - American Standard Code for Information Interchange. A seven or eight bit code used to represent alphanumeric characters. It is the standard code used for communications between data processing systems and associated equipment.

2.EBCDIC: - Extended Binary Coded Decimal Interchange Code. It is an 8-bit character encoding (code page) used on IBM mainframe operating systems suchas z/OS, OS/390, VM and VSE, as well as IBM minicomputer operating systems such as OS/400 and i5/OS (see also Binary Coded Decimal). 

66.What are the various registers in 8085?Accumulator register, Temporary register, Instruction register, Stack Pointer, Program Counter are the various registers in 8085 .

67.In 8085 name the 16 bit registers?Stack pointer and Program counter all have 16 bits.

68..What are the various flags used in 8085?A.Sign flag, Zero flag, Auxillary flag, Parity flag, Carry flag.

69.What is Stack Pointer?Stack pointer is a special purpose 16-bit register in the Microprocessor, which holds the address of the top of the stack.

70.What is Program counter?Program counter holds the address of either the first byte of the next instruction to be fetched for execution or the address of the next byte of a multi byte instruction, which has not been completely fetched. In both the cases it gets incremented automatically one by one as the instruction bytes get fetched. Also Program register keeps the address of the next instruction.

71.Which Stack is used in 8085?LIFO (Last In First Out) stack is used in 8085.In this type of Stack the last stored information can be retrieved first.

72.What happens when HLT instruction is executed in processor? The Micro Processor enters into Halt-State and the buses are tri-stated.

73.What is meant by a bus? A bus is a group of conducting lines that carriers data, address, & control signals.

74.What is Tri-state logic?Three Logic Levels are used and they are High, Low, High impedance state. The high and low are normal logic levels & high impedance state is electrical open circuit conditions. Tri-state logic has a third line called enable line.

75.Give an example of one address microprocessor?8085 is a one address microprocessor.

76.In what way interrupts are classified in 8085?In 8085 the interrupts are classified as Hardware and Software interrupts.

77.What are Hardware interrupts?TRAP, RST7.5, RST6.5, RST5.5, INTR.

78.What are Software interrupts?RST0, RST1, RST2, RST3, RST4, RST5, RST6, RST7.

79.Which interrupt has the highest priority?TRAP has the highest priority.

80.Name 5 different addressing modes?Immediate, Direct, Register, Register indirect, Implied addressing modes.

81.How many interrupts are there in 8085?There are 12 interrupts in 8085.

82.What is clock frequency for 8085?3 MHz is the maximum clock frequency for 8085.

83.What is the RST for the TRAP?RST 4.5 is called as TRAP.

84.In 8085 which is called as High order / Low order Register? Flag is called as Low order register & Accumulator is called as High order Register.

85.What are input & output devices?A.Keyboards, Floppy disk are the examples of input devices. Printer, LED / LCD display, CRT Monitor are the examples of output devices.

86.Can an RC circuit be used as clock source for 8085?A.Yes, it can be used, if an accurate clock frequency is not required. Also, the component cost is low compared to LC or Crystal.

87.Why crystal is a preferred clock source? A.Because of high stability, large Q (Quality Factor) & the frequency that doesn’t drift with aging. Crystal is used as a clock source most of the times.

88.Which interrupt is not level-sensitive in 8085?A.RST 7.5 is a raising edge-triggering interrupt.

89.What does Quality factor mean?A.The Quality factor is also defined, as Q. So it is a number, which reflects the lossness of a circuit. Higher the Q, the lower are the losses.

90.What are level-triggering interrupt?A.RST 6.5 & RST 5.5 are level-triggering interrupts

91.What are the flags in 8086? A.In 8086 Carry flag, Parity flag, Auxiliary carry flag, Zero flag, Overflow flag, Trace flag, Interrupt flag, Direction flag, and Sign flag.

92.What are the various interrupts in 8086?A.Maskable interrupts, Non-Maskable interrupts.

93.What is meant by Maskable interrupts? An interrupt that can be turned off by the programmer is known as Maskable interrupt.

94.What is Non-Maskable interrupts?An interrupt which can be never be turned off (ie.disabled) is known as Non-Maskable interrupt.

95.Which interrupts are generally used for critical events?A.Non-Maskable interrupts are used in critical events. Such as Power failure, Emergency, Shut off etc.

96.Give examples for Maskable interrupts?A.RST 7.5, RST6.5, RST5.5 are Maskable interrupts

97.Give example for Non-Maskable interrupts?A.Trap is known as Non-Maskable interrupts, which is used in emergency condition.

98.What is the Maximum clock frequency in 8086?A.5 Mhz is the Maximum clock frequency in 8086.

99.What are the various segment registers in 8086?A.Code, Data, Stack, Extra Segment registers in 8086.

100. Which Stack is used in 8086?A.FIFO (First In First Out) stack is used in 8086.In this type of Stack the first stored information is retrieved first.

101. What are the address lines for the software interrupts? -1.RST 0 0000 H2.RST1 0008 H3.RST2 0010 H4.RST3 0018 H5.RST4 0020 H6.RST5 0028 H7.RST6 0030 H8.RST7 0038 H

102. What is SIM and RIM instructions?A.SIM is Set Interrupt Mask. Used to mask the hardware interrupts. RIM is

Read Interrupt Mask. Used to check whether the interrupt is Masked or not.

103. Which is the tool used to connect the user and the computer?A.Interpreter is the tool used to connect the user and the tool.

104. What is the position of the Stack Pointer after the PUSH instruction?A.The address line is 02 less than the earlier value.

105. What is the position of the Stack Pointer after the POP instruction?A.The address line is 02 greater than the earlier value.

106. Logic calculations are done in which type of registers?A.Accumulator is the register in which Arithmetic and Logic calculations are done.

107. What are the different functional units in 8086?A.Bus Interface Unit and Execution unit, are the two different functional units in 8086.

108. Give examples for Micro controller?A.Z80, Intel MSC51 &96, Motorola are the best examples of Microcontroller.

109. What is meant by cross-compiler?A.A program runs on one machine and executes on another is called as cross-compiler.

110. What are the address lines for the hardware interrupts? -1.RST 7.5 003C H2.RST 6.5 0034 H3.RST 5.5 002C H4.TRAP 0024 H

111. Which Segment is used to store interrupt and subroutine return address registers?A.Stack Segment in segment register is used to store interrupt and subroutine return address registers.

112. Which Flags can be set or reset by the programmer and also used to control the operation of the processor?A.Trace Flag, Interrupt Flag, Direction Flag.

113. What does EU do?A.Execution Unit receives program instruction codes and data from BIU, executes these instructions and store the result in general registers.

114. Which microprocessor accepts the program written for 8086 without any changes?A. 8088 is that processor.

115. What is the difference between 8086 and 8088?A.The BIU in 8088 is 8-bit data bus & 16- bit in 8086.Instruction queue is 4 byte long in 8088and 6 byte in 8086.

116. Differences between Latch and Flip Flops?Latch is a level sensitive device while flip-flop is an edge sensitive device.Latch is sensitive to glitches on enable pin, whereas flip-flop is immune to glitches.Latches take less gates (also less power) to implement than flip-flops.Latches are faster than flip-flop.

117. Difference between C and C++?C follows the procedural programming paradigm while C++ is a multi-paradigm language(procedural as well as object oriented)In case of C, importance is given to the steps or procedure of the program while C++ focuses on the data rather than the process.Also, it is easier to implement/edit the code in case of C++ for the same reason.In case of C, the data is not secured while in C++ data is secured(hidden) due to specific OOP features like data hiding.C is a low-level language while C++ is a middle-level language

118. Which semiconductor device is used as a voltage regulator and why?Ze·ner diode : A silicon semiconductor device used as a voltage regulator because of its ability to maintain an almost constant voltage with a wide range of currents.

119. Ideal Voltage Source?An ideal voltage source is a mathematical abstraction that simplifies the analysis of electric circuits. The internal resistance of an ideal voltage source is zero; it is able to supply or absorb any amount of current. The current through an ideal voltage source is completely determined by the external circuit.

120. Explain zener breakdown and avalanche breakdown?Avalanche breakdown is caused by impact ionization of electron-hole pairs. While very little current flows under reverse bias conditions, some current does flow. The electric field in the depletion region of a diode can be very high. Electron/holes that enter the depletion region undergo a tremendous acceleration. As these accelerated carriers collide with the atoms they can knock electrons from their bonds, creating additional electron/hole pairs

and thus additional current. As these secondary carriers are swept into the depletion region, they too are accelerated and the process repeats itself.Zener breakdown occurs in heavily doped pn-junctions. The heavy doping makes the depletion layer extremely thin. So thin, in fact, carriers can’t accelerate enough to cause impact ionization. With the depletion layer so thin, however, quantum mechanical tunnelling through the layer occurs causing current to flow. The temperature coefficient of the Zener mechanism is negative : the breakdown voltage for a particular diode decreases with increasing temperature.

121. What are the different types of filters? lowpass, highpass, bandpass, bandstop, allpass and notch filters.

122. What is the need of filtering ideal response of filters and actual response of filters?Real filters for real-time applications approximate the ideal filter by truncating and windowing the infinite impulse response to make a finite impulse response; applying that filter requires delaying the signal for a moderate period of time, allowing the computation to "see" a little bit into the future. This delay is manifested as phase shift. Greater accuracy in approximation requires a longer delay.

123. FIR vs IIR filters?1.IIR is infinite and used for applications where linear characteristics are not of concern.2. FIR filters are Finite IR filters which are required for linear-phase characteristics.3. IIR is better for lower-order tapping, whereas the FIR filter is used for higher-order tapping.4. FIR filters are preferred over IIR because they are more stable, and feedback is not involved.5. IIR filters are recursive and used as an alternate, whereas FIR filters have become too long and cause problems in various applications.

124. Why the input resistance of an op-amp is high whereas it's output resistance is low?The op amp gain is assumed to be infinite, hence it drives the output voltage to any value required to satisfy the input conditions. This assumes that the op amp output voltage can achieve any value. Saturation occurs when the output voltage comes close to a power supply rail, but reality does not negate the assumption, it only bounds it. Also, implicit in the infinite gain assumption is the need for zero input signal. The gain drives the output voltage until the voltage between the input leads (the error voltage) is zero. This leads to the third assumption that the voltage between the input leads is zero. The implication of zero voltage between the input leads means that if one input is tied to a hard voltage source such as ground, then the other input is at the same potential. The current

flow into the input leads is zero, so the input impedance of the op amp is infinite. Four, the output impedance of the ideal op amp is zero. The ideal op amp can drive any load without an output impedance dropping voltage across it. The output impedance of most op amps is a fraction of an ohm for low current flows, so this assumption is valid in most cases.

125. What do you understand by microwaves? why these are called micro?Microwaves are electromagnetic waves with wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz (0.3 GHz) and 300 GHz.While the name may suggest a micrometer wavelength, it is better understood as indicating wavelengths much shorter than those used in radio broadcasting.

126. How do microwave oven work?MO heats food by dielectric heating. This is accomplished by using microwave radiation to heat polarized molecules within the food. Many molecules (such as those of water) are electric dipoles, meaning that they have a partial positive charge at one end and a partial negative charge at the other, and therefore rotate as they try to align themselves with the alternating electric field of the microwaves. Rotating molecules hit other molecules and put them into motion, thus dispersing energy. This energy, when dispersed as molecular vibration in solids and liquids (i.e., as both potential energy and kinetic energy of atoms), is heat.

127. What is CMRR? Explain briefly.The common-mode rejection ratio (CMRR) of a differential amplifier (or other device) measures the tendency of the device to reject input signals common to both input leads. A high CMRR is important in applications where the signal of interest is represented by a small voltage fluctuation superimposed on a (possibly large) voltage offset, or when relevant information is contained in the voltage difference between two signals. (An example is audio transmission over balanced lines.)

128. Difference between Diode rectifier and SCR?

129. What is intersymbol interference?In telecommunication, intersymbol interference (ISI) means a form of distortion of a signal that causes the previously transmitted symbols to have an effect on the currently received symbol. This is usually an unwanted phenomenon as the previous symbols have similar effect as noise, thus making the communication less reliable. ISI is usually caused

by echoes or non-linear frequency response of the channel. Ways to fight against intersymbol interference include adaptive equalization or error correcting codes (especially soft-decoding with Viterbi algorithm).

130. Biasing?

131. Race Around Problem?A condition in logic network in which the difference in propagation times through two or more signal paths in the network can produce an erroneous output.in jk flip flop race around problem will occur when both the inputs are high. it can be prevented by using master slave jk flip flop.

132. What is sampling theorem?It is defined as the sampling frequency should be greater than or equal to twice the sampling frequency then we can generate the original signal if the condition does not satisfy we get the signal in the distorted mannerit is given as ( fs >/ 2 fs).

133. Yagi-Uda Antenna?A Yagi-Uda array, commonly known simply as a Yagi antenna, is a directional antenna consisting of a driven element (typically a dipole orfolded dipole) and additional parasitic elements (usually a so-called reflector and one or more directors). 

134. RS-232?In telecommunications, RS-232 (Recommended Standard 232) is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE (Data Terminal Equipment) and a DCE (Data Circuit-terminating Equipment). It is commonly used in computer serial ports.

135. VOIP?Voice over Internet Protocol (Voice over IP, VoIP) is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet

136. FPGA?A field-programmable gate array (FPGA) is an integrated circuit designed

to be configured by the customer or designer after manufacturing—hence "field-programmable"

137. ZigBee?ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802 standard for personal area networks. Applications include wireless light switches, electrical meters with in-home-displays.

138. Principle of Transformer?The transformer is based on two principles: first, that an electric current can produce a magnetic field (electromagnetism), and, second that a changing magnetic field within a coil of wire induces a voltage across the ends of the coil (electromagnetic induction). Changing the current in the primary coil changes the magnetic flux that is developed. The changing magnetic flux induces a voltage in the secondary coil.

139. Piconet and Scatternet? A piconet is the type of connection that is formed between two or more Bluetooth-enabled devices such as modern cell phones.A scatternet is a number of interconnected piconets that supports communication between more than 8 devices.

140. TCS products and services?TCS BancsDigital Certification ProductsHealthcare Management Systems OutsourcingBPOSoftware Products

141. Analog Circuit Vs Digital Circuit?The way an analog circuit processes a signal is different from a digital circuit. Analog means that a continuum of values are possible for a circuit. For example, if the boundaries were -5 and +5 volts, any value between -5 and +5 would be interpreted by the circuit. Digital is completely different. A digital circuit breaks up the domain into discrete regions, and anything falling into that region is treated the same.

142. How can you convert +5v to -5v?

143. Advantage of DC over AC transmission?1. No reactance. Voltage drop is reduced.2.Has a lower line resistance than AC, thus it will have a lower line loss.3.In DC system frequency is zero: thus we need not monitor abrupt frequency changes.4.Easier analysis.

144. A 12v regulated dc power supply has a voltage regulation of 0.5% find magnitude of variation?

145. Ripple rejection?Ripple Rejection is the ability of an amplifier to maintain accurate output voltage despite AC fluctuations in the power supply.

146. Difference b/w Microprocessor and Microcontroller?1.The major difference between a microprocessor and a microcontroller are their functions. Where a microprocessor has more generalized functions, a microcontroller is more specific to its task.2.A microprocessor may not also be programmed to handle real-time tasks whereas a microcontroller such as in devices that need to control temperature of water or perhaps measure the temperature of a room require real time monitoring and therefore with its inbuilt set of instructions the microcontroller works on its own.3.A microprocessor requires constant input by a human such as in a personal computer so that instructions can be boot. A microprocessor is the memory of the computing machine whereas the microcontroller integrates the entire computer in a single chip.

147. Principle of electrical fan?Electric fan works on the principle of electromagnetic induction.there are two parts of this one is stator and other is rotar.induction machine are ac machines.stator is given single phase ac voltage which produces sinuosoidal flux and emf is induced in the rotar and acc to lenz law current flows in a direction so as to oppose the cause that has produced effect in this case it rotates in similar direction as that of sinuosoidal field..and rotar rotates so blades attached to it also rotates.

148. Embedded System?An embedded system is a computer system designed to do one or a few dedicated and/or specific functions often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts.

149. Polarised Capacitors?Electrolytic capacitors are polarised and they must be connected the correct way round, at least one of their leads will be marked + or -. They are not damaged by heat when soldering.

150. Difference b/w PLC and embedded System?An embedded system is typically made to do one set of task or similar sets of tasks. An internet router uses an embedded system and so does an MP3 player. There are usually some options as to how the task are carried out, such as choosing to set a password for your router or choose a song on the MP3 player. PLC's on the other hand, operate using IF-THEN instructions. If the water gets too high, THEN open the valve to release some. IF the water gets too low, THEN turn on the pump. A PLC can be used to operate a whole process, like brewing beer or refining fuel. Most PLC's connect to many different types of sensors for inputs. Some examples of these sensors are: flow, pressure, temperature, and level, but there are many more. Outputs usually are connected to relays to control power to electrical devices that require more current than the PLC can put out. A PLC may also interface with an embedded system. There are some cases where either will do. One commonly used appliance that would work with either is an automatic coffee maker. Also, clothes washing machines used to use simple PLC's while many of the new ones use embedded system.

151. HLR?The Home Location Register (HLR) is the main database of permanent subscriber information for a mobile network. The HLR is an integral component of CDMA (code division multiple access), TDMA (time division multiple access), and GSM (Global System for Mobile communications) networks. Maintained by the subscriber's home carrier (or the network operator where the user initiated the call), the HLR contains pertinent user information, including address, account status, and preferences

152. Technique used in telegraphy?Multiplexing originated in telegraphy, and is now widely applied in communications.Several workers were investigating acoustic telegraphy, a frequency-division multiplexing technique, which led to the invention of the telephone.

153. Response of an RLC circuit to impulse signal is? Decaying exponential.

154. LASCR can be turned on by? light/gate pulse. Either.

155. Routh Array?The Routh array is a tabular procedure for determining how many roots of a polynomial are in the right-half of the s-plane. We can also determine if there are any roots on the jw axis and their locations. An important use of the Routh array is to determine upper and lower limits on the value of some parameter, such as gain, so that all roots of the closed-loop characteristic equation are in the left-half plane.More: http://en.wikibooks.org/wiki/Control_Systems/Routh-Hurwitz_Criterion

156. Logic Swing?The voltage difference between the logic levels used for 1 and 0; magnitude is chosen arbitrarily for a particular system and is usually well under 10 volts.

157. Advantages of DTL over RTL?Diode-Transistor Logic, or DTL, refers to the technology for designing and fabricating digital circuits wherein logic gates employ both diodes and transistors. DTL offers better noise margins and greater fan-outs than RTL, but suffers from low speed, especially in comparison to TTL.

158. Different Logic Family technologies?The list of packaged building-block logic families can be divided into categories, listed here in rough chronological order of introduction along with their usual abbreviations:

I. Resistor–transistor logic  (RTL)II. Direct-coupled transistor logic  (DCTL)III. Resistor–capacitor–transistor logic (RCTL)IV. Diode–transistor logic  (DTL)V. Complemented transistor diode logic (CTDL)VI. High-threshold logic  (HTL)VII. Emitter-coupled logic  (ECL)VIII. Positive emitter-coupled logic  (PECL)IX. Low-voltage positive emitter-coupled logic  (LVPECL)X. Gunning transceiver logic  (GTL)XI. Transistor–transistor logic  (TTL)XII. P-type metal–oxide–semiconductor logic  (PMOS)XIII. N-type metal–oxide–semiconductor logic  (NMOS)XIV. Depletion-load NMOS logic XV. Complementary metal–oxide–semiconductor logic  (CMOS)XVI. Bipolar complementary metal–oxide–semiconductor

logic (BiCMOS)XVII. Integrated injection logic  (I2L)

159. Dark current ? dark current is the relatively small electric current that flows through photosensitive devices such as a photomultiplier

tube, photodiode, orcharge-coupled device even when no photons are entering the device. It is referred to as reverse bias leakage current in non-optical devices and is present in all diodes. Physically, dark current is due to the random generation of electrons and holes within the depletion region of the device that are then swept by the high electric field.

There is a twofold increase in dark current for a temperature rise from 5°C to 10°C. 

160. Laplace transform ?the Laplace transform provides a useful method of solving certain types of differential equations when certain initial conditions are given, especially when the initial values are zero.The Laplace transform of a function f(t) for t > 0 is defined by the following

integral defined over 0 to ∞: { f(t)} =  .

More on : http://www.intmath.com/laplace-transformation/intro.php

161. Unit of admittance?Admittance (Y) is a measure of how easily a circuit or device will allow a current to flow. It is defined as the inverse of the impedance (Z). The SI unit of admittance is the siemens (symbol S).

162. Kirchoff’s Laws ?Kirchhoff's circuit laws are two equalities that deal with the conservation of charge(KCL) and energy(KVL) in electrical circuits, and

were first described in 1845 by Gustav Kirchhoff.KCL: At any node (junction) in an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node. KCL is only valid if the charge density remains constant at the point to which it is applied.KVL: The sum of the emfs in any closed loop is equivalent to the sum of the potential drops in that loop.

163. Which of the sensor cannot be used for static measurements?Piezoelectric sensors. A static force will result in a fixed amount of charges on the piezoelectric material. While working with conventional readout electronics, imperfect insulating materials, and reduction in internal sensor resistance will result in a constant loss of electrons, and yield a decreasing signal.

164. Potentiometer?A potentiometer , informally, a pot, is a three-terminal resistor with a sliding contact that forms an adjustable voltage divider.[1] If only two terminals are used (one side and the wiper), it acts as a variable resistor or rheostat. Potentiometers are commonly used to control electrical devices such as volume controls on audio equipment. Potentiometers operated by a mechanism can be used as position transducers, for example, in a joystick.

165. Electromagnetic Spectrum?The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation.[1] The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object.

166. Input Impedance of CRO?1 megohm .(Range)

167. LASER?A laser is a device that emits light (electromagnetic radiation) through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation.

168. Population Inversion? Population inversion occurs when a system (such as a group of atoms or molecules) exists in state with more members in an excited state than in lower energy states.

169. Shunt?In electronics, a shunt is a device which allows electric current to pass around another point in the circuit.An ammeter shunt allows the measurement of current values too large to be directly measured by a particular ammeter. 

170. A galvanometer can be made to read high currents by..? Connecting a shunt resistance of low value in parallel.