SECTION A


1. answer any three of the fOllowing:
A continous time LTI systemS described by <img src='./qimages/1101-1a1.jpg'> Find the impulse response of the system. Is the system casual?
For the circuit shown below, find i1, i2,i3, and i4 <img src='./qimages/1101-1a2.jpg'>
A transmission line of characteristics impedance Zo 50ohm is terminated by load
impedance RL=ZL=100ohm Find voltage standing wave ratio VSWR, minimum impedance Zmm impedance Zmax.
Find the qualifactor Qp at resonance for the circuit shown below <img src='./qimages/1101-1a4.jpg'>
Design a combinational circuit that accepts a three-bit number and generates an output binary numb er equal to the square of the input number.
(ii)design a second-order active RC band pass filter with a mid-band voltage gain-A0=34dB, carrier frequency 160HZ and 3dB bandwidth 16hz assume C1=C2=0.1mewF.
(c)(i)explain the principle of split-phase,single-phase induction motor. discuss resistance split-phase motors and capacitor split-phase motors.
explain why an induction motor is not run under conditions of maximum load
(i)calculate the depth of penetration for copper at 1 MHz the conductivity for copper is 58M and permeability is 1.26mewH/m
discuss the merits of delayed AGC as compared with single ACC
show that the first minor lobe is -13.5 dB to principal maxima for broadside array for large n.
find img src='./qimages/1101-2a1.jpg'> assume the switch 1 has been opened for switch 2 has been closed for along time and steady state condition prevails at t=0 img src='./qimages/1101-2a1-2.jpg'>

a parallel plate waveguide consists of two parallel perfectly conducting infinite planes situated 8cm apart.determine the propagating TEmo for a wave of 6000MHz,assuming free space between the plates.find also the cut-off frequency fc, wavelength lamdag, waveguide intrinsic impedance ng.
list the three sources of instability of collector current define the three stability factors.which biasing arrangement gives you better stability?

Define voltage regulation of a transformer. Derive the expression for voltage regulation at lagging power factor. Draw phasor diagram.

A single-phase transformer working at unity power factor as an efficiency of 90% at both half full load and full load. Full load is 500 W. Determine the efficiency at 60% of full load condition. 10
What is a TRIAC? Explain its characteristic. Discuss its applications, advantages and disadvantages.
voltage across SCR is 1V when it is conducting. It has a holding current of 2mA when gate current 0. If the SCR is triggered on by momentary pulse of gate current to what value must VA be reduced in order to turn the SCR off? the figure is shown below. <img src='./qimages/1101-2c2.jpg'>

3.(a)(i)Using the difference equation design method with a backward difference, design a digital filter to simulate the analog filter whose transfer function is <img src='./qimages/1101-3a1.jpg'>
find the poles and zeros of the networks given below. <img src='./qimages/1101-3a2.jpg'>
(iii)implement the Boolean function
15)
with an 8x1 multiplexer with B and D connected to selection lines S2,s1,s0
respectively.

Explain speed -current and torque current characteristics of d.c. series motor.

4-pole d.c. generator has 1200 armature conductors and generates 250 volts on open circuit when running at a speed 0f 600 r.p.m. The diameter of the po1e-shoe circle is 0-35m and the ratio of pole arc to pole pitch is 0.7 while the 1ength of pole­shoes is 02 m. find the mean flux density in the air gap. Assume lap-connected armature winding.
what are the steps involved for the generation of gating signals for thyristors of ac. to d.c. converters? Draw a block diagram incorporating various stages of firing circuits for a single-phase fully controlled rectifier.
If the SCR in the following figure is continuously fired by average value of the current <img src='./qimages/1101-3c2.jpg'>
For the network shown below, find the current ratio transfer function given by alpha=I2/I1 <img src='./qimages/1101-4a1.jpg'>

Explain boundary conditions for time varying fields.
(iii)draw the signal model of FET. Define mew,gm and rd, and obtain relationship between them.
when a super heterodyne receiver is turned to 555 kHz, its local oscillator provides the mixer with an input at 1010kHz. what is the image frequency? The antenna of this receiver is connected to the mixer via a tuned circuit whose loaded Q is 40 what will be the rejection ratio for the calculated image frequency?

Show that power contained in one side b and is 1/6 to the total power of amplitude­modulated signal at 100% modu1ation index.
(c)(i)Explain Faraday rotation isolator. A matched isolator has insertion loss of 0-5 dB and isolation 25 dB, Calculate the scattering co efficient.
Explain construction of Ionosphere.
Determine v for the circuit shown below when vs=10 cos 30t V <img src='./qimages/1101-5a1.jpg'> find the Fourier transform of the signal <img src='./qimages/1101-5a2.jpg'> (iii)Find the Laplace transform of the stepped waveform shown below. <img src='./qimages/1101-5a3.jpg'> An air filled rectangular waveguide of dimension a=4cm,b=2cm, transports energy in the dominant mode at a rate of 2mW if the frequency of operation is 10GHz.determine the peak value of electric field in the waveguide.
the 741C op-amp having the following parameters is connected as shown in the figure. <img src='./qimages/1101-5b1.jpg'> 20000, Ri= 2 Moam, RD= 75oam f0= 5Hz, supply voltage =± 15 output voltage swing ± 13V. IdentifY the circuit. Compute the values of AF, RIF, ROF, fF &VOUT

How much noise voltage is generated in a 1 M oam resistance at 27°C over a 10kHz bandwidth? List the sources of noise in an amplifier.

what are the conditions for distortion less transmission in continuous time LTI systems and discrete time LTI systems?
A three-phase star-connected synchronous generator is rated at 1.5MVA and 11KV. The armature effective resistance and synchronous and are 1.2 ohms and 25 ohms respectively per phase. Calculate the percentage equation for a load of 1.4375 MVA at 0.8 power factor lagging 0.8 power factor leading.

Explain qualitatively with sketches as to how armature reaction effect in a synchronous machine can be modeled reactance.


In a trapezoidal pattern displaying modulation, the length of the long vertical side is 5 cm, and of the short vertical side,2cm. Determine the modulation depth.
Explain Foster-seeley discriminator circuit with the help of phasor diagram.

(iii)Describe transmission radiation modes of helix.

6.(a)Find the inverse z-transform of <img src='./qimages/1101-6a1.jpg'>

(ii)Obtain the three-dimensional wave equation for an absorbing medium, assumed to be both magnetically and electrically homogenous and isotropic. The charge density in the field may be assumed to be zero. Hence, determine the wave equation if the field is varying harmonically with time.

A sequential circuit has one input and one output. The state diagram is shown in the figure. Design the sequential circuit using D flip-flop.
<img src='./qimages/1101-6a3.jpg'>


Three regular d1ce are thrown Assign probabilities to the following events The sum of the points appearing on three dice is and 15.
(ii)Explain central limit theorem.

(c)(i)Explain the term 'virtual height' with respect to ionospheric transmission. Calculate the transmission-path d1stance for an ionosphenc transmission that utilizes a layer of height 200 km The angle of elevation of the antenna beam is 20° consider flat earth.
Explain varactor diode.give its equivalent circuit.give its application.
Explain the different input statements in SPICE.

Design an m -derived pie-section high-pass filter having characteristic impedance 600 ohm, cut-off frequency 5kHz and infinite attenuation at 4kHz.

Using a bipolar 32 x 8 PROM, implement the following equations simultaneously:
F1= E summation
F2 summation
F3 E summation

Describe 'third method' of generating an SSB-SC signal.

Explain envelope detector circuit with input and output waveforms.

Draw and explain construction details of reflex klystron. Explain electronic tuning.
Explain test setup for VSWR measurement.

Find the CTFS harmonic function for the signal 4 2 cos (20piet) sin (40 piet) by sampling above the Nyquist rate over exactly one fundamental period and finding the DTFS harmonic function of the samp1es.

(ii)Find the input impedance of the circuit shown be1ow, omega 1000 rad/s. <img src='./qimages/1101-8a2.jpg'>

Draw the circuit diagram of voltage to current converter with floating load using op-amplifier derive the necessary equation.
Describe the effect on the speed-torque characteristic of a 3-phase induction motor by (1)reducing the applied voltage to half the normal voltage but normal frequency and reducing both applied voltage and frequency to half the normal value.

4-pole, 50Hz, 3-phase induction motor has a rotor resistance of 4.5 ohms per phase and a standstill reactance of 8.5 ohms per phase. With no external resistance in the circuit, the starting torque of the motor is 85 Nm. Calculate the rotor voltage at standstill, starting torque if a resistance of 2 ohms is added in each rotor phase.

Describe single-phase d. c. drive considering a phase-controlled converter supplying a d.c. motor load. With the help of a circuit diagram, explain the operation of a single­phase full converter circuit feeding a separately excited motor.

d.c. drive runs at 900 r.p.m. on no load when fed at 2OOV d.c. from a full converter. Calculate the triggering angle of the converter thyristors if the motor has to run at 600 r.p.m. on no load. Input to the converter is 230 V a.c. Neglect IaRa drop.