7th Semester Electronics and Communication Engineering (Dec-2015; Jan-2016) Question Papers

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Power Electronics
Time: 3 hrs. Max. Marks:100
Note: Answer FIVE full questions, selecting * hat least TIYO questionsfrom each port. ,q * W
PART _ A *,q*'
f; I a. Give symbol, characteristic features of the following devices: ",-'
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E GTO, TRIAC, MOSFET, UJT, SCR <1,*
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E b. Explain briefly the different types of thyristor power converter$qhnd mention two
K applications of each. ,"ra. , t (10 Marks)
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g 2 a. With the necessary waveforms, explain the switching characffiipics of a power transistor.
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8.E b. Give the comparison between MOSFET and IGBT. *,**i (06 Marks)y > - r-
EA c. The collector clamping circuit of Fig. Q2 (c) has V-" =I00 V, Rc =1.5 e), Vd, =2.1 Y,
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: 16. Calculate
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1 E 3 a. Defure the.foffir,,ing: i) latching current ii) holding current iii) I2t ratrng
E i Derive exffiSion for Anode current using two-transistor model in case of SCR. (10 Marks)
g € b. Wha{h"#ifh6 need for protection of thyristor? Explain how thyristors are protected against
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g and hieh 9. (06 Marks)E5 ruS
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3 load resistance of 10 O. Find the suitable values for the components of the snubber circuit.
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; ".fl 4 a. Explain the working of single phase dual converter with neat circuit diagram. Draw relevant
€ waveforms (10 Marks)
Z b. Explain the working of single phase semiconvert with neai circuit and waveforms. Derive
! expression for the average output voltage. (06 Marks)
a c. A single phase full converter supplies an RLE load from a230 V, 50 Hz supply. The load is
tE highly inductive, so that load current is continuous and ripple free. If R = 1 f) and the load
current is In = 10A. Calculate the delay angle g for E:.120.
Collector clanyiag
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(04 Marks)

2. 5a.
b.
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PART _ B
Explain the operation of a single phase bidirectio4al controller with resistive load. Obtain
the expression for rms output voltage. Show the waveforms. (10 Marks)
A single phase fullwave AC voltage controller has an RL load. The input voltage is 230 V,
6a.
b.
50 Hzand the load is R : 2 f) and Xt- = 2Q, o, = dt =1. Calculate the following:
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r) Angle until which the thyristor conducts. *&-
ii) Conduction angle of thyristor. (ii) Conduction angle of thyristor. 'ff*iii) RMS voltage of output. {"-}; CI6 Marks)
What are the advantages and disadvantages of ON-OFF control and pha&CUntrol of ac
voltage controller?
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(04 Marks)
Explain the resonant pulse commutation with neat circuit and waveffith. (10 Marks)
Explain the working of complementary commutation circuit. Draw fdlbvant waveforms.
Derive expression for ton ;%w (06 Marks)
c. In the circuit of Fig. Q6 (c) the capacitor is i"_rt#$ charged to a voltage of
%(0) = -500 V. If L = 15 pH and C : 50 pF and the SRSs turned ON at t: 0. Calculate
(i) the peak value of resonant current and (ii) the c@ffition time of thyristor. (04 Marks)
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Fig. Q6 (c)
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Give the classification of cffifper. Explain briefly each one of them. (10 Marks)
Explain the principle offfiffition of a step up chopper. (06 Marks)
A dc chopper has aninfrrt voltage of 200 V and a load of 8 O resistance. The voltage drop
across thyristor ig 2'V and the chopper frequency is 800 Hz. The duty cycle K: 0.4. Find
i) Average oytput voltage
ii) RMS output voltage
7a.
b.
c.
iii) Cho ciency. (04 Marks)
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8 a. E;gHWthe performance parameters of inverters. (06 Marks)
b. Effiin the working of transistorized current source inverter. (08 Marks)
c. {,sblculate the rms values of the fundamental and the two lower order harmonics of a single-
. uJ phase full bridge inverter employing single-pulse width modulation for output voltage!
..r,}.-t$ control. The modulation index is 80% and the dc input voltage is 230 V. (06 Marks)
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Embedded System Design
Time: 3 hrs. Max. Marks:100
Note: Answer FIVE full questions, selecting
at least TWO fuertins Trom each Part-
PART _ A
List out the differences between RISC and CISC architecture. ,r, *l (00 Marks)
Discuss the purpose of a Watch dog timer in an embedded application. (06 Marks)
Briefly describe the major elements of the embedded system development 1l .V.lfm
Marks)
2 a. What is meant by the arity of an instruction? Explain the terms one, two, three address
instructions. (04 Marks)
b. What are the four major categories of execution flow through an embedded program?
Briefly describe what each means. (08 Marks)
c. Explain RTN model for a microprocessor Datapath and memory Interface with neat
diaeram. (08 M99ks)
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itCbinbare SRAM and DRAM
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'Eiplain the internal diagram of DRAM arldivrite the timing diagram for read and write
operation. fl , 'n' (08 Marks)
c. Write a short note on memory Hier4refuJ (04 Marks)
d. Explain associative mapping cache lm lementation. (04 Marks)
4 a. Briefly explain V cycle model and spiral model. (10 Marks)
b. What are Five steps to a successful design? (04 Marks)
c. Explain system snecifigfions versus system requirements. (06 Marks)
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#*i r.ExplainTask stffiagram. (05 Marlc):,pi
b. Differentiatelqtff€en single thread and multi thread process. (05 Marks)E O. lJlllergnllaleJ&lwtrgn surBrg rrusau au(r rrulLr Llrrs4Lr Pru,s)s. lvJ rvr4rnv
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A c. Explain T**4*dbntrol Block (TCB). (05 Marks)
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; d. What isffireground and Back ground systems? (05 Marks)
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fr E 6 a. @S*context switching? Describe the sequence of steps that are necessary to handle an
I E q*itrirence of an intemrpt. (06 Marks)
lE $ffiphin Three kinds of stack. (06Marks)
$ Y" . .h*J! f)oo^rihc .rirfrrol rnndel onrl hioh lewel mndel fnr OS architecfttres (08 Marks).H [ .{ chl Describe virtual model and high level model for OS architectures. (08 Marks)
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E H ffie L Explain Andahl,s law. (04 Marks)
E" H*4 b. Wiite a oc' function to determine the sum of the elements in an array and analyze it line by
oK " line for its time complexity. (06 Marks)
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: " c. Explain Big - O notation. (05 Marks)
€ d. What are the different operations that can be performed on Arrays and linked list and also
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analyze the time complexity. (05 Marks)
A I a. Explain memory loading with equations and examples. (10 Marks)
E b. Explain the trade tricks to optimize the code for performance improvement. (10 Marks)
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Seventh Semester B.E. Degree Exami
Real Time Systd
Tirne: 3 hrs.
Note: Answer any FIVE full questions, selecting
atleast TWO questions from each purt"
PAR.T _ A
a. Define RTS and compare hard and soft real time systems.
b. Explain the ctrassification of RTS based on synclronization between external
internal tasks of the computer.
Explain the classification of programming.
Conrpare batch processing and continuous processing with examples.
With a neat diagram, explain supervisory control.
Explaiii hierarchical system with an exarnple.
3 a. Explain the different forms of parallei computers with diagrams.
tr. Expiain analog interface for input and output operations.
c" Explain the various methods of D.M.A.
4 a. Explain the following features of real - time programming languages :
i) Security
ii) Flexibility
iii) Portability.
b. Explain the following with respect to programming languages :
i) Scope and visibility of variables
ii) Exception handling
iii) derived data types
iv) Fointers.
c. Write a note on control structures used in programming languages.
PART _ B
a. Explain what do you mean by rninimal operating system.
b. Explain the stmctr.re of a real - time operating system.
c. Explain the priority levels in real - time operating systern"
Explain the general structure of an input/output subsystem"
Expiain the following with respect to R.TOS :
i) Sernaphores
ii) Data transfer without synchronization.
V/rite a note on liveness of a RTS.
Explain the basic software modules with reference to RTS.
Exptrain the muiti tasking approach to impiernent software design of R:TS.
Explain rnutual exclusion using condition flags.
(06 Marks)
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(08 Marks)
(06lV1arks)
a. Sumrnarize the various methodologies used for designing real tirne systerns. {06 Marks}
b. Expiain the general arrangement of drying over along with the functional specifications"
c. Explain the q,utline of abstract modeling approach of Ward and Mellor.
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Seventh Sernester B.E. Degree Examination, Dec.2015/Jan.2016
lmage Processing
Tirne:3 hrs. &4ax. Marks:100
Note: ,4nswer any FIVE full questians, selecting atleast TWO qwestions f,row eack parl
PART _ A
a. With a blcck diagram, explain the fundamental steps involved in Dig,ital Lnage Frocessing"
(tr0 Ndarks)
b. With a neat diagram of the eye. explain the human visual s;izstern working. (tS I4arks)
What is meant by path? Give the formula for calculating Do and Ds distances. What is the
difference between Ds distance and D,, distance? (18 Marks)
For V : i2,3,4), compute the lengths of shoftest4,8 and m path between p and cl in the
following irnage. (06 Marks)
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22 314
(p) 30 421
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c. Expiain spatial resolution and gray level resolution. ($4 Marks)
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a.
b.
civen A 1[J] '--lr*o irnase , = [l 2l
. calculate the
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basis ir:rages.
What are the properties of Unitary Transforms?
Construct 4 x 4 DFT matrix and show that it is unitary.
4a.
b.
Write the recursive definition of Hadamard Transform and
transfom for N: 8.
Detennine 4 x 4 slant transform matrix. List its properties.
using this, construct l{adamard
(10 Marks)
(10 S{arks)
PART _ B
Perform histogram equalization of an image whose pixel intensity dlistribution is siven in
Table :
Grav levels 0 1 2
i
J 4 5 5 7
Number of Pixels 790. 1023 850 656 329 24s 122 81
Construct the histogram of the images before and after equalization. (n0 Marksl
b. What is meant by Laplacian filter? Using the second derivative, develop a Laplacian mask
f,or image sharpening.
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b.
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With the heip of a block dragram, explain the steps involved in frequency domain filtering.
(10 Marks)
With ther help rcf a block diagrarn, explain the Homomorphic filtering approach fbr image
enhancernent. What are the advantages of these filters? (10 Marks)
a. Explain the rnodel of image degradation / restoration. (08 Marks)
b. What are the three methods of estimating the degradation function? Explain each of thern.
(12 Marks)
a" Describe RGB color, model with the help of neat diagram. Write equations to convert R.GB
to CMY. (10 Marks)
b. What is Fseudo colour? Explain any one type of pseudo colour processing with a neat
functional block diagram. (10 Marks)
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Seventh Semester B.E. Degree Examina
Optical Fiber Gommunication
Note: Answer any FIW full questions, selecting
atleast TWO questions from each part.
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PART _ A
I a. Differentiate between :
i) single mode and multimode fibers
ii) step index and graded index multimode fibers.
Time: 3 hrs.
2a.
b.
c.
b. What are the different types of fiber materials used in optical fibers, explain briefly.
(06 Marks)
c. A MMGI fiber has a core with a parabolic refractive index profile, with a diameter of
60 pm. The fiber has an NA of 0.2. Estimate the total number of propagating modes at a
wavelength of 1 pm. (04 Marks)
A MMGI fiber has a cone refractive index of 1.46, cladding RI of 1"45. The critical radius of
curvature at which maximum bending loss occurs is 0.84 pm. Determine wavelength of the
transmitted light. (04 Marks)
Derive the expression foilquantum efficiency and output power for an LED. (08 Marks)
Describe the different noise sources affecting the photo detector along with expressions and
derive the expression for the SA.,l ratio at the O/P of the photo detector. (08 Marks)
c. The quantuffi,efficiency for an APD is 90%. Find the responsivity at 1600 nm. (04 Marks)
4 a. Name the different types of fiber joints. Explain the types of mechanical misalignments
Explain the material absorption mechanism in an optical fiber.
Derive the expression for material absorption in an optical fiber.
y&jt. joining two fibers.
Explain the three types of fiber splicing techniques with neat diagram.
5a.
b.
An optical fiber has a cone RI of 1.5. Two perfectly aligned optical fiber lengths one butted
together. Calculate the optical loss in decibels at the joints when there is an air gap between
the fiber end faces. (04 Marks)
PART - B
Draw the signal path through an optical digital link showing all the relevant waveforms.
(06 Marks)
Draw and explain the two general heterodyne receiver configurations, along with the
relevant expressions for BER. (08 Marks)
c. Draw and explain the two types of front end amplifiers in optical fiber communication.
(06 Marks)
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b.
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Draw the block diagram,and explain the multichannel amplitude
in fiber optics.
Explain the significance of link power budget and system margin.
parameters are given :
Optical power launehed :6 dBm
Receiver sensitivity : -25 dBm
. Source 1 detector connector loss : 1 dB
Fiber cable length : 100 km
Cable attenuation :0.1 dB/km
Jumper cable loss : 3 dB
Connector loss at each joint : ldB
Assume two jurnber cables and two cable joints.
c. Derive the total system rise time expression for a
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(08 Marks)
The following optical link
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digital optical link.
7 a. With the help of a diagram, explain the principle of WDM.
b. Draw and explain the operation and design of : ".;
i) Optical isolators
ii) Mems technology
iii) Tunable optical filters.
Write short notes on :
a. EDFA amplifier
b. SONET/SDH.
(06 Marks)
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(08 Marks)
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Time: 3 hrs.
Note: Answer FIVE full questions, selecting
at leust TWO questions from each parl
PART _ A
I a. With a neat diagram explain TCP/IP reference model. How do the
correlate to the OSI models?
b. Name the major components of a telephone networks.
c. What is ADSL? Explain the operation of ADSL using discrete multitone
neat diagram.
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layers of TCP/IP model
(10 Marks)
(04 Marks)
modulation with a
(06 Marks)
Seventh Semester B.E. Degree Examination, Dec.2015 I Jan.20l6
Gomputer Gommunication Networks
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2 a. Explain nomal response mode (NRM) and Asynchronous Balanced Mode (ABM) in
HDLC. (04 Marks)
b. What is ARQ? In stop and wait ARQ system the bandwidth of the line is lMbps and it takes
20ms to make roundtrip. What is the bandwidth delay product? If the system data frames are
of 1000bit length, what is utilization percentage of the link? (04 Marks)
c.
3a.
b.
c.
c.
5a.
4a.
b.
What are sliding window protocols? Explain Go back - N protocol for noisy channel.
(12 Marks)
Explain 1 - persistent, non - persistent and p - persistence with flow diagram. (06 Marks)
With a flow diagram explain CSMA/CA protocol. (08 Marks)
What are the reasons for poor channel utilization in ALOHA system? How the same is
improved in CSMA? (06 Marks)
Explain frame format of 802.3 MAC frame. (06 Marks)
Define the type of the following destination addresses.
i)4,A.: 30 : 10 :21 : 10 : 1A ii)FF : FF : FF : FF : FF : FF 11i)47 : 20 : 1B : 2E : 08 :EE.
(06 Marks)
What is a Fast Ethernet? Mention the goals of fast Ethernet. Explain autonegotiation.
(08 Marks)
PART _ B
A system with four LAN's and five bridges is shown in Fig. Q5(a). Choose 81 as the root
bridge. Show the forwarding and blocking ports, after applying the spanning tree procedure.
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10. b.
6a.
b.
c.
ta.
8a.
b.
What are virtual LAN's? Enumerate the advantages of having VLAN's.
Find the class of the following IP address :
1) 237.t4.2.r 11) t29.t4.6.8 iii) 208.35.54.12 iv) tr4.34.2.8
Compare IPV4 and IPV6 packet headers.
What is NAT? Explain now NAT help in address depletion.
With suitable diagram explain distance vector routing.
Explain the different forwarding techniques used to forward the packets from
destination.
Explain with diagram the TCP segment format.
Write short notes on :
i) Domain name system (DNS)
ii) Resolution.
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