SIGNALS AND SYSTEMS

SIGNALS AND SYSTEMS

• 1.      All the signals are basically Vectors
• 2.      A vector can be represented in terms of its co-ordinates
• 3.      A signal is said to be periodic if it repeats at regular intervals
• 4.      The condition for periodicity of continuous time signal is x(t)=x(t+T₀)
• 5.      Trigonometric Fourier series can be represented in Compact Form
• 6.      Single Valued Property must have only one value at any time instant within time interval T₀

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Antenna Wave Propagation

Antenna Wave Propagation

      1.      A communication system always involves a Spectrum or Band of Frequencies

      2.      Modulation may be defined as a process by which any characteristics of a wave is varied as a function

      3.      To radiate or receive electromagnetic waves an Antenna is required
4.      The boundary sphere between antenna region and free space region appears as opaque
5.      Electric field intensity is defined as the force on Unit Test Charge
6.      Lord Kelvin devised a method known as the IMAGE METHOD
7.      Magnetostatics can also be named as the Static Magnetic Current or Steady Electric Field Current
8.      The magnetic flux tubes are Continuous
9.      A Helical Soil or Solenoid is usually used to produce a magnetic field
10.  Fraday’s law gives the e.m.f induced in a closed circuit due to change of magnetic flux
11.  The electromagnetic equations derived earlier are Maxwell’s equation
12.  A homogeneous medium is that medium in which the quantities are constant
13.  The energy radiated in a particular direction by an antenna is measured interms of FIELD STRENGTH
14.  Different parts of radiation pattern referred to as LOBES
15.  Gain is closely associated with Directivity
16.  Directive gain depend entirely on the distribution of Radiative Power in Space
17.  Antenna band width is a measure of directivity of an antenna
18.  An antenna array is said to be Linear
19.  Broad side array is also known as Broad Side Couplet
20.  The minor lobes just adjacent to the main lobe are called Side Lobes
21.  The technique used in reduction of side lobe are called as Tapering
22.  The vertical radiator may be either Vertical Wire or Metallic Mast
23.  Electrically short antennas are generally used as Vertical Grounded Antennas
24.  Beverage or wave antenna is a non-resonant antenna
25.  There are two methods of exciting a tower antenna known as Series Excitation and Shunt Excitation
26.  The field distribution in vertical plane of a vertical grounded radiator depends upon the Height
27.  The V Antenna is an extension of long wire antennas
28.  V Antenna provides Multi Band Operation
29.  Resonant or Tuned Antenna considered in the HF band
30.  The Rhombic Antenna is based on the principle of Travelling Wave Radiator
31.  Rhombic arrays is one that is used for receiving purposes only in Multiple-Unit-Steerable Antenna
32.  Travelling Wave or Aperiodic Antenna are those antennas in which there is no Reflected Anteena
33.  A Radio Direction Finder is used to find determine of arrival of a radio signal
34.  The term Direction Finder has a special sense and general sense

35.  The radiation efficiency of closed loop antenna is low for transmission purposes\

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MICROWAVE ENGINEERING

MICROWAVE ENGINEERING

• 1.      Microwaves have large band widths compared to common bands
• 2.      Fading effect due to variation in the transmission medium is more effective at low frequencies
• 3.      EM waves are oscillations that propagate through free space
• 4.      The TEM waves are propagated equally in all directions if the source is a point source
• 5.      Series junction is also known as E-Plane TEE
• 6.      The spherical TEM wave is known as a plane wave
• 7.      Electric and Magnetic fields are purely transverse to the direction of propagation
• 8.      Transmission lines can also be used as Circuit Elements
• 9.      The magnitude of standing wave can be measured interms of Standing Wave Ratio
• 10.  The TWT is an O-Type device
• 11.  The magnetron is a self contained Microwave Oscillator
• 12.  IMPATT is an abbreviation form of Impact Ionization Avalanche Transit Time
• 13.  Two modes of negative resistance devices are Voltage Controlled Mode and Current Controlled Mode
• 14.  Bolometer is also known as Square Law Device
• 15.  In low VSWR measurement, value of VSWR is less than 10

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DSP Lab - SAMPLE viva questions

DSP Lab - SAMPLE viva questions

1.What is MATLAB?
2.What are the applications of MATLAB?
3.State sampling theorem.
4.What is meant by Nyquist rate and Nyquist criteria?
5.Explain scaling and superposition properties of a system.
6.What is meant by linearity of a system and how it is related to scaling and superposition?
7.What is impulse function?
8.What is meant by impulse response?
9.What is energy signal? How to calculate energy of a signal?
10.What is power signal? How to calculate power of a signal?
11.Differentiate between even and odd signals.
12.Explain time invariance property of a system with an example.
13.What is memory less system?
14.When a system is said to have memory?
15.What is meant by causality?
16.Explain linear convolution and circular convolution.
17.What is the length of linear and circular convolutions if the two sequences are having thelength n1 and n2?
18.What are Fourier series and Fourier transform?
19.What are the advantages and special applications of Fourier transform, Fourier series, Ztransform and Laplace transform?
20.Differentiate between DTFT and DFT. Why it is advantageous to use DFT in computersrather than DTFT?In DTFT, frequency appears to be continuous. But, in DFT, frequency is discrete.This property is useful for computation in computers.
21.How to perform linear convolution using circular convolution?If two signals x (n) and y (n) are of length n1 and n2, then the linear convolutedoutput z (n) is of length n1+n2-1. Each of the input signals is padded with zeros tomake it of length n1+n2-1. Then circular convolution is done on zero paddedsequences to get the linear convolution of original input sequences x (n) and y (n).
22.What is meant by correlation?Correlation is the measure of similarity between two signal/waveforms. Itcompares the waveforms at different time instants.
23.What is auto-correlation?It is a measure of similarity of similarity of a signal/waveform with itself.
24.What is cross-correlation?
25.What are the advantages of using autocorrelation and cross correlation properties insignal processing fields?
26.How auto-correlation can be used to detect the presence of noise?
27.Differentiate between IIR filters and FIR filters

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PULSE AND DIGITAL CIRCUITS

PULSE AND DIGITAL CIRCUITS

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• 1.      The capacitor which totally blocks D.C not allowing it to reach output is called Blocking Capacitor
• 2.      The magnitude of the ratio of output to input called Transfer Function
• 3.      The average level of the output signal is always zero, under Steady State
• 4.      Critical Resistance  is the value of  resistance which reduces square root term to zero
• 5.      Damping Ratio is the indication of the opposition from the circuit to cause oscillations in its response
• 6.      The Clipper Circuits are used to remove the unwanted portion
• 7.      The forward resistance of diode is small and cut-in voltage is also small, the diode is assumed to be an Ideal Diode
• 8.      The  diode with pieces of  straight lines, the name given to such approximation is PieceWise-Linear method
• 9.      If there are two clipping levels they are known as Double Ended Clipper
• 10.  When a transistor used as Switch , it is usually made to operate alternately
• 11.  The Bistable Multi-Vibrators is used to drive the other circuits
• 12.  The waveform at the emitters is more important in the Monoshot
• 13.  The time required for the return to the initial value is called the Restoration Time
• 14.  Sampling gate is also referred to as Transmission Gate
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• 15.  Sampling gate may be broadly classified as Uni-Directional or Bi-Directional

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SWITCHING THEORY AND LOGIC DESIGNING

SWITCHING THEORY AND LOGIC DESIGNING

• 1.      Numeric codes used to represent decimal digits are called BCD codes
• 2.      Each 4 bit binary group is called a Nibble
• 3.      The consenus theorem is also called Included Factor theorem
• 4.      A bubbled AND gate is equivalent to a NOR gate
• 5.      A 16 square eliminates four square
• 6.      Sub cubes in the K-map from either Square or Rectangles
• 7.      An arithematic circuit that adds only two binary digits is called a Half-Adder
• 8.      The Look-Ahead adder speeds up the process by eliminating the ripple carry
• 9.      The complement of a unite function is Ultra-Violent light
• 10.  Threshold functions can be realized using a single threshold gate
• 11.  The input signals to a flip flop are called Excitations
• 12.  Dynamic shifters are made up of MOS Invertor
• 13.  Unspecified outputs provide additional flexibility in state reduction
• 14.  A state machine is another name of Sequential Circuit
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• 15.  Moore type of outputs referred to as unconditional outputs 

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MICROWAVE ENGINEERING

MICROWAVE ENGINEERING

• 1.      Microwaves have large band widths compared to common bands
• 2.      Fading effect due to variation in the transmission medium is more effective at low frequencies
• 3.      EM waves are oscillations that propagate through free space
• 4.      The TEM waves are propagated equally in all directions if the source is a point source
• 5.      Series junction is also known as E-Plane TEE
• 6.      The spherical TEM wave is known as a plane wave
• 7.      Electric and Magnetic fields are purely transverse to the direction of propagation
• 8.      Transmission lines can also be used as Circuit Elements
• 9.      The magnitude of standing wave can be measured interms of Standing Wave Ratio
• 10.  The TWT is an O-Type device
• 11.  The magnetron is a self contained Microwave Oscillator
• 12.  IMPATT is an abbreviation form of Impact Ionization Avalanche Transit Time
• 13.  Two modes of negative resistance devices are Voltage Controlled Mode and Current Controlled Mode
• 14.  Bolometer is also known as Square Law Device
• 15.  In low VSWR measurement, value of VSWR is less than 10
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DIGITAL COMMUNICATION

DIGITAL COMMUNICATION

• 1.      The codes developed during the four decades after hamming were definitely achieving practically Error-Free communication
• 2.      The information sources most of in the nature are analog in nature
• 3.      The communication channel has a finite Band Width
• 4.      Geometric representation of signals, which greatly simplifies Signal Detection process
• 5.      Channels such as under water acoustic channels are molded as Linear Time Variant Filter channels
• 6.      Gaussian Distribution is used in the various fields of science and engineering
• 7.      The conversion of analog form of signal to discrete form takes place in Quantiser
• 8.      Crest Factor describes how strong the signal peak value is with respect to its RMS value
• 9.      In Adaptive PCM the efficiency can be further improved by allowing the system to adapt to the slowly time varying stastics
• 10.  Coding can’t generate additional information nor it destroy exisisting information
• 11.  Huffman code was generated by American scientist D.A.Huffman in 1952
• 12.  Huffman or Shannon-Fano codes which belongs to the class of  Fixed to Variable Length Codes
• 13.  Information capacity theorem is also referred as Hartley-Shannon Law
• 14.  If the weights remain fixed during the transmission of the data the equalization is Preset
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• 15.  Power eefficency of a coherent detection is Optimum

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ELECTRONIC DEVICES AND CIRCUITS

ELECTRONIC DEVICES AND CIRCUITS

1.      Valence Electrons are the electrons present in the outermost orbit
2.      The element that does not have three valence electrons is Gallium
3.      The ripple frequency for a full wave rectifier is twice the supply frequency
4.      The primary function of a rectifier filter is to Removes Ripples
5.      Power transistors are invariably provided with Heat Sink
6.      The common emitter transistor High Gain
7.      The practical range of stability factor is from 1 to 10
8.      An amplifier in Voltage Divider Bias configuration is the most widely used one
9.      The input and output impedance of a CC amplifier is Large and Small
10.  The power gain of a CB amplifier is approximately equal to Current Gain
11.  For small values of drain-to-source voltage, JFET behaves like a Resistor
12.  A depletion MOSFET differs from a JFET in the sense that has no PN-Junction
13.  A uni-junction transistor has two Bases and One Emitter
14.  The voltage gain of common drain amplifier is always Less than 1
15.  The tunnel diode can be used as a Logic Memory Storage device

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ANTENNA & WAVE PROPAGATION

ANTENNA & WAVE PROPAGATION

1. The process of transmitting electromagnetic waves into space is known as radiation.

2. Capacitance of a parallel plate capacitor is C=EA/d farad.

3. The emf induced in a closed circuit due to change of magnetic flux.

4. Radiation intensity defined as power per unit solid angle.

5. Rhombic antenna is used on the principle of travelling wave tube.

6. The average pointing vector of a far field is given by p=1/2R(E*H*).

7. The receiving antenna abstract energy from the passing Electromagnetic field.

8. Optical low attenuation can be as 0.2 dB/km.       

9. Radiation resistance dissipates an amount of power that is equal to Radiated power.

10. The product of the pattern of the individual antenna with its array pattern is called      Principle of pattern multiplication.

11.Flat sheet reflector is the simplest form of reflector antenna.

12. The fundamental parameters of a single mode fiber is mode field diameter.      

13. The angle at which two plane reflector is given by Included angle.

14. Electric charge density p=Q/V.

15. Directivity of loop antenna is max radiation intensity/Avg radiation intensity.

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ELECTRIC CIRCUITS & ANALYSIS

ELECTRIC CIRCUITS & ANALYSIS

1. What is the type of capacitor used in RC coupled amplifier for a) coupling two phases b) by pass emitter

   Ans: Generally electrolytic capacitors are used.

2. List out the different types of biasing.

Ans:

·         Voltage divider bias

·         Base bias

·         Emitter feed back bias

·         Collector feedback bias

   3. Define current amplification factor?

 Ans: It is defined as the ratio of change in output current to the change in input current at  constant other side voltage.

4. What is biasing?

Ans: To use the transistor in any application it is necessary to provide sufficient voltage and current to operate the transistor. This is called biasing.

 5. What is an amplifier?

 Ans: An amplifier is a device which produces a large electrical output of similar             characteristics to that of the input parameters.

   6. What is feed back?

Ans: It is the process of injecting some energy from the output and then returns it back to the input.

   7. What is a tuned amplifier?

Ans: The amplifier with a circuit that is capable of amplifying a signal over a narrow band of frequencies are called tuned amplifiers.

8. The ratio of reactance to resistance is Q factor.

9. What is Oscillator circuit?

Ans: A circuit with an active device is used to produce an alternating current is called an oscillator circuit.

10. A Multivibrator has two states. They may be either stable or quasi stable state.

11. Astable Multivibrator has two quasi stable states.

12. A monostable Multivibrator having one stable state and another quasi stable state.

13. Positive feedback is the type of feedback used in an op-amp Schmitt trigger.

14. F = 1 / (2πRC) is the expression for the frequency of oscillations in an op-amp sine                wave oscillator.

15. What is meant by voltage follower?

   Ans: If the output voltage of an op-amp follows the input i.e., if the output voltage is equal            to the input voltage it is called as a voltage follower.

  16. The operational amplifier is a multi-terminal device, which is quite complex internally.

  17. Positive feedback ,Negative feedback are the types of feed back.

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INTEGRATED CIRCUITS

INTEGRATED CIRCUITS

1.      The counter type is Direct type of ADC.

2.      Subtractors are designed using Adder ICs.

3.      Square wave outputs are generated when the Op-amp is forced to operate in the saturation region.

4.      10 FFs are required to build a binary counter circuit to count from 0 to 1023.

5.      The DACs use level amplifiers to account for variations in logic levels.

6.      A  Bidirectional shift register allows shifting of data either to the left or right.

7.      In 741 Op-amp 24 transistors are used.

8.      Clip-off a certain portion of the input signal is called clippers.

9.      Regenerative comparator is called Schmitt trigger.

10.  Voltage control oscillator is a free running multi- vibrator.

11.  Phase detection is most important part in the PLL system.

12.  In voltage follower output voltage is equal to input voltage.

13.  In integrated circuits all the components are fabricated on the same chip.

14.  Linear ICs are available in the flat pack, metal can and dual-in-time package.

15.  A feedback amplifier is sometimes referred to as a closed loop amplifier.

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