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Page No ... 1 INEW SCHEME I EC51USN

Fifth Semester B.E. Degree Examination, January/February 2005EC/TE/BM/ML

Analog CommunicationTime: 3 hrs.] [Max.Marks : 100

Note: Answer any FIVE full questions.1. (a) Define standard form of amplitude modulation and explain each term.(4 Marks)

(b) Explain with the help of a neat sketch, how square law modulator is used togenerate AM. (6 Marks)

(c) An audio frequency signalS sin 27r ( l O O O ) t is used to amplitude modulate acarrier of 100 sin 27r (106 )t. Assume modulation index as 0.4. Findi) Sideband frequenciesii) Amplitude of each sidebandiii) Bandwidth requirediv) Total power delivered to a load of loon . (10 Marks)

2. (a) What is DSB-SC modulation? What are the advantages and limitations ofDSB-SC as compared to standard AM? (5 Marks)

(b) Explain how ring modulator can be used to generate DSB-SC modulation.(9 Marks)

(c) Define:i) Hilbert transformii) Pre-envelopeiii) Complex envelope (6 Marks)

3. (a) Derive an expression for SSB modulated wave for which upper sideband isretained. (8 Marks)

(b) Explain how downward frequency translation is achieved with the help of ablock diagram. (8 Marks)

(c) What are the features of HDTV? What are its limitations? (4 Marks)4. (a) Define angle modulation. Describe with the help of block diagrams, schemes

for generating. (8 Marks)i) FM wave using PM ii) PM wave using FM.

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Page No... 2 EC51(c) An angle modulated signal is described by

s(t) =10co.s[27r(106)t + 0.1 sin (103) t ] .Fjnd message signal m(t)i) Considering s(t) is PM with kp =10ii) Considering s(t) is FM with J ~ f = 5 (5 Marks)

5. (a) Describe with necessary equations and block diagram: the generation ofnarrow band FM. (6 Marks)(b) Explain the demodulation of FM wave using zero crossing detector. (7 Marks)(c) Determine the instantaneous frequencies of the following signals.

i) 4cos(1807r + f)ii) 10 cos (87rt + 7rt2)iii) cos 1007rt cos(sin27rt) + sin 1007rt sin (sin27rt) (7 Marks)

6. (a) What is conditional probability? Prove that P(AB) =P(B/A)P(A)(5 Marks)

(b) Discuss the properties of Gaussian process. (10 Marks)(c) The probability density function (PDF) of a random variable is given as

Jx(x) = f l ' i : for x betweer: 2 and 4., l oth.eruiis eWhere k is a constant. Sketch the PDF and determine the value of k.

(5 Marks)7. (a) What is noise equivalent bandwidth? Derive an expression for noise equivalent

bandwidth. (8 Marks)(b) Derive an expression for power spectral density of noise n( t ) . Draw the power

spectral density of noise n( t ) , in-phase component n I( t ) and quadrature com-ponent nQ(t) in a high Q tuned filter shown in the figure below.

CD~ i'.02

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INEW SCHEME IUSN

fth Semester B.E. Degree Examination, January/February 2005EC/TE/BM/MLDigital Signal Processing

e No... 1 EC52

ime: 3 hrs.] [Max.Marks: 100Note: 1. Answer any FIVE full questions.2. Use of normalized chebyshev Butterwortbprototype tables NOT allowed.

1. (a) Let xp (n ) be a periodic sequence with fundamental period N. Let Xl(k)denote the N-point DFT of one period of xp(n) and X3(k ) be the 3N-pointDFT of three periods of xp(n). What is the relationship between X l( k ) andX3(k ) for ~ k ~ N -1. (10 Marks)

(b) Let x(n) be any N-point sequence and X(k) be the corresponding N-pointDFT. Suppose that xl(n) = x((m - n))N' where ~ m ~ N - 1 . Startingfrom the definition of DFT, find X1(k), the N-point DFT of the sequencex l( n). Using this result, and any other properties of DFT, determine X l(k )if x l( n) = x(( 2 - n))s, if the first five values of the 8-point DFT of a realvalued sequence are as follows:

{16, -(2 J2 + 2) - j(2J2 + 2),0, (2 J2 - 2), -j(2J2 - 2).0} (10 Marks)2. (a) A long sequence x(n) is filtered through a filter with impulse response h(n) to

yield the output y(n). If x(n)= {I, 1, 1,1,1,3, 1,1,4,2,1,1,3, I}, h(n) = {I-I},compute y(n) using the overlap save technique. Use only a 5-point circularconvolution in your approach. (12 Marks)

(b) Consider a finite-duration sequence x(n)={O, 1,2,3,4,5}.i) Sketch the sequence s( n) with 6-point DFT S(k) =W2kX (k).ii) Determine the sequence y(n) with 6-point DFT Y(k)=ReX(k), the real

part of X(k). (8 Marks)3. (a) Starting from the definition, prove the following:

i) "E ~(/ y(n) = "E~=( / xl(n) "E~=( / x2(n), where xl(n) and x2(n) are twoN-point sequences and y(n) the N-point circular convolution of xl(n)and x2(n).

ii) " E ; ; 2 o 1 x( n) 1 2 = * ' " E f ~ o 1 X(k) 1 2 , where x(n) is an N-point sequence,and X(k) the corresponding N-point DFT. Prove any intermediate resultthat you may use. (8 Marks)

(b) Let x(n)= 25(n) + 5(n - 1) + 5(n - 3). Obtain the sequence y(n) whose5-point DFT Y(k)= (X(k))2 , where X(k) is the 5-point DFT of x(n).(4 Marks)(c) Let x(n) be the following 8-point sequence:x(n)= { J z ' 1, J z ' 0, - J z ' -1, - J z ' O}.Use the decimation-in-time FFT algorithm to compute the DFT ofthe abovesequence. Provide the values at the intermediate stages. (8 Marks)

4. (a) Let X(k), ~ k ~ N - 1, to be discrete Fourier transform of a sequence x(n).How would you use an FFT algorithm to compute the inverse DFT (i.e.,obtain x(n) from X(k))? Hence determine the sequence x(n) whose 8-point

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Page No ... 2 EC52(b) Consider the sequence x(n) = u(n)- u(n-8). Using chirp-z transform,

determine the following values X ( zo) and X ( zd where Zo = e j 2; and Zl =j4 -rre 8 (8 Marks)

5. (a) Design a lowpass digital filter using bilinear transformation. The filter isto be monotonic in both stop-and pass-bands and has all of the followingcharacteristics: . (i) an acceptable passband ripple of 1 dB, (ii) a passbandedge of 0.371"ad, and (iii) stopband attenuation of 40dB or greater beyond0.671"ad. (16 Marks)

(b) Transform the alalog filter H(s) = (S+~n !+2) to a digital filter using thematched z-transforrn. Let T=0.5sec. (4 Marks)

6. (a) Using the impulse reaponse technique, design a lowpass digital filter thatis equiripple in the passband, and monotone in the stopband. The filterpassband edge is at 0.171"ad with a ripple of 2.5 dB or less, and the stopbandedge at 0.2-rrrad with attenuation 40 dB or more. Use T=1. (16 Marks)(b) Transform the analog filter H(s)= s~Ct.' Ct . > 0 to a digital filter using thebackward- difference mapping. Comment on the stability of the digital filter.

(4 Marks)7. (a) Let the specifications on a filter be as follows:0.99 ~I H ( e jW ) I~1.01, 0 ~ w ~ 0.271"

I H ( e jW ) I~ 0.05, 0.2571"~ W ~ 0.6-rr,0.99 ~I H (e jW ) I~ 1.01, o.v- ~ w ~-rr

(i) These specifications approximate an ideal filter. Derive the impulseresponse of this ideal filter.

(ii) Design a linear-phase filter that satisfies the above specifications usingthe Kaiser window. Give the expression for the impulse response of thedesigned filter. (10 Marks)(b) Starting from a lowpass Butterworth prototype alanog filter, design a fourth-

order Butterworth bandpass analog filter with upper and lower band edgefrequencies 10radjsec and 5radjsec. (4 Marks)

(c) Consider an FIR lattice filter with coefficients Kl = 0.65, K2 =-0.34, k 3 =0.8. Find its impulse response. Draw the equivalent direct-form structure.(6 Marks)8. (a) By choosing an appropriate window, design a linear-phase, odd-length, low-

pass FIR filter that satisfies the following specifications:0.985 ~I H ( e jW) I~ 1.015, 0 ~ w ~ 0.271",

I H ( e jW) I~ 0.001, 0.371"~ W ~ 71"Give the expressions for the impulse response and the corresponding frequencyresponse. (8 Marks)

1_lz-1(b) Consider the system function H(z) = 1 15-2) 1(l-zz-l+:rz (1+"4z-1)

i) Realise the system in direct form 1.ii) Realise the system in cascade form using first- and second-order form IIsections.

iii) Realise the system in parallel form using first- and second-order direct.form II sections. (12 Marks)** * **

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No ... 1[NEW SCHEME I EC53

USNSemester B.E. Degree Examination, January /Febr~ary 2005

EC/TE/BM/MLTransmission Lines & Wave Guides.

me: 3 hrs.) [Max.Marks: 100Note: 1."Answer any FIVE full questions.

2. Use of Smith chart permitted wherever pertinent.1. (a) 'A line of finite length, terminated in a load equivalent to its characteristic

impedance, appears to the sending end generator as an infinite line'. Establishthe statement starting from the fundamentals. (14 Marks)

(b) Show that for a distortionless line, the characteristic impedance will be apure resistance. (6 Marks)

2. (a) What is insertion loss? Derive an expression for insertion loss in terms ofreflection factors. (8 Marks)

(b) A 16gauge cable, 80 kmlong, is inserted between a generator of 2V, 600n, W =5000rad/ see and terminated in Z o o Find the decibel loss in power in the load.Characteristics of 16 gauge cable are:

R L C G26.6n/~m 0.63mH/Km 0.039J.Lf/km 0.94J.L /Km

(6 Marks)(c) Compute the elements of a constant K lowpass network having cutoff fre-

quency fe =2000 cycles and load of 5000n(6 Marks)

3. (a) Differentiate between trvelling waves and standing waves. (4 Marks)(b) Show that the input impedance ofOC and SC lossless lines are purely reactive.

(8 Marks)(c) Show that the maximum and minimum impedances on the line for a lossless

line is given by Ro.S and Ro/ S. (8 Marks)4. (a) Explain standing waves, standing wave ratio, reflection co-efficient. Derive

the relation between them. (8 Marks)(b) Explain the quarter wave transformer. (6 Marks)(c) A lossless line of characteristic resistance Ro = lOOn is terminated by a

load which gives VSWR = 3 operating at 300MHz frequency. During themeasurements the first voltage maximum of 10 volts appeared at a distance

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Page No ... 2 EC535. (a) The terminating load of transmission line (Zo = 5~ D) working at 300MHz

is (50 + j50) ohms. Calculate VSW~ and reflection co-efficient.(6 Marks)

(b) Derive equations for the length and location of the single stub matchingdevice in terms of the reflection co-efficient of the transmission line.(8 Marks)

(c) A lossless transmission line operating at one GHz has reflection coefficientof K =0.5~. Determine the length and location of the single stub formatching the line. (6 Marks)

6. (a) A lossless line of characteristic resistance Ro = 300D operating at 45MHzfrequency is connected to a load of 75D. Determine the lengths and locationof two short circuited stubs which are to be placed at )..14 distance apart toproduce impedance matching. (use Smith chart) (7 Marks)

(b) Starting fromMaxwell's equations, derive the expressions for field componentsfor TE waves travelling between infinitely conducting parallel planes.

(7 Marks)(c) For frequency of 6000 mega cycles and plane separation =7cm, find the cut

off frequency, phase constant and wavelength. Is it possible to propagateTE 3 mode? (6 Marks)

7. (a) Discuss various TEmn modes that can exist in rectangular waveguides andwrite their cutoff wavelengths. What is the advantage of having only onedominant mode in case of TEm,n propagation. (8 Marks)

(b) Find the cutoff frequencies for a dominant TEmn wave in air in rectangularwaveguide measuring 5cm x 2.5cm. Calculate phase & group velocities atfrequency of 6000 megacycles. (6 Marks)

(c) Write the field pattern for TE 20andT E lO modes in rectangular wave guide.(6 Marks)

8. (a) What is cavity resonator? Show that cavity resonator has only one frequencyof resonance for a given mode. List out applications of cavity resonator.(12 Marks)

(b) Discuss the methods of exciting various modes in rectangular waveguides.(8 Marks)

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No ... 1 INEW SCHEME I EC54USN

Semester B.E. Degree Examination, January/February 2005EC/TC

Advanced Microprocessors: 3 hrs.)

Note: Answer any FIVE full questions.2. All questions carry equal marks.1. (a) Trace the development of intel 86 family of microprocessors briefly indicating

the additional features introduced at each stage of development from 8086 toPentium IV. (10 Marks)

[Max. Marks: 100

(b) Enumerate the user programmable registers of the 8086 processor. Describetheir general and special uses. (6 Marks)(c) State the segments use d in calculating the physical memory address in thefollowing instructions :

i) MOV AX, [BP+6]Ii) MOV AX, [DI+6] (4 Marks)

2. (a) Explain with examples, different addressing modes of the 8086 processor.(10 Marks)

(b) Explain the (MOD-REG-R/M) byte of an 8086 instruction, with itsinterpretations. (5 Marks)(c) What do the following instructions do? (5 Marks)

i) ROLiii) SARv) XCHG AX, [BX]

ii) RCLiv) STD

3. (a) An unsorted 16 bit integer word array starts at address ARRAY-ST and hasin all n words. Write an 8086 ALP to generate two different arrays fromit - one of positive numbers, starting at memory address ARRAY -.POS andthe other of negative numbers starting at address ARRAY_NEG. Use stringinstructions as far as possible. (10 Marks)

(b) Write an 8086 ALP to multiply a 2-digit BCD number by a single digit BCDnumber by repeated addition, using DAA instruction. (5 Marks)(c) Convert a 2-digit BCD number in AL, to a 2-digit Hex number in AL, usingthe AAD instruction. (5 Marks)

4. (a) Explain the assembler directives PUBLIC and EXTRN with a simpleexample. (6 Marks)

(b) Distinguish between MACRO and a procedure.(c) Write an 8086 ALP using DOS interrupts to read a two digit

number and display the same on the console.

(4 Marks)hexadecimal

(10 Marks)

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Page No ... 2 EC545. (a) With appropriate circuit diagrams, explain how you would generate, data,address and control buses for memory and I/O interfacing from an 8086processor in the MAX mode of operation. (10 Marks)

(b) Indicate the action of the LOC f( pin using a timing diagram, when executingthe instruction LOCK: X CRG AX, [SI], in an 8086 system. (4 Marks)(c) Draw the timing diagram showing all relevant signals for a memory writecycle in an 8086 system in the MAX mode with no WAIT state. (6 Marks)

6. (a) i) On receiving a hardware interrupt, the 8086 processor pushes the flag tothe stack and clears the TF and the IF before doing any further operation.Explain why this is required. (6 Marks)ii) Even though interrupt service routine is similar to any procedure rou-tine, the last instruction of an interrupt routine is IRET which is codeddifferently from the RET instruction of the subroutine return. Explainthe reasons for this separate IRET instruction. (4 Marks)

(b) The 8086 processor has no instruction to manipulate the trace flag. Considerwhile debugging a program, a uses wants the traceflag to remain set, over aportion of the program so that in that region of the program, single steppingis automatically introduced. Write a user generated software interrupt rou-tine, that toggles the trace flag when invoked, so that the user invokes thisinterrupt at the start of the specific region in the program where he desiresto single step, and invokes the same interrupt again at the end of the region(where he wants to stop single stepping). (10 Marks)7. (a) Write an 8086/8087 system ALP to find the frequency response characteristicof a series L-C-R circuit in the form of a table. Assume the response tocorrespond to the power expended in the L-C-R at constant input voltagewith varying frequency. (10 Marks)

(b) Indicate the basic features of the PCI Bus or the USB.(c) Describe the basic 486 architecture.

(5 Marks)(5 Marks)

8. Write short notes on :i) ASCII arithmetic in the 86 family of microprocessors.ii) Parallel printer interface.iii) Pentium microprocessor.

(6 Marks)(7 Marks)(7 Marks)

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No ... 1 INEW SCHEME I EC55USN

Fifth Semester B.E. Degree Examination, January/February 2005EC/TE

Telecommunication & Switchinge: 3 hrs.] [Max.Marks: 100

Note: Answer any FIVE full questions.

1. (a) Explain the theory and working of a simplex telecommunication system.(8 Marks)

) Explain with a neat diagram the operation of a carbon granule microphone.(8 Marks)

(c) List t~e basic functions of a switching system. (4 Marks). (a) Explain the advantages of automatic exchanges over the manual exchanges.

(10 Marks)

(b) 'What is DTMF? Explain the working of a push button dial system.(lO Marks)(a) From the basic principles of queuing systems, derive the equation for finite

queue capacity. (8 Marks)(b) On an average, during the busy hour, a company makes 180 outgoing calis of

average duration 3 minutes. It receives 400 incoming calls of average duration6 minutes. Findij The outgoing trafficii) The incoming trafficiii) The total traffic. (6 Marks)

(c) In a group of 24 servers each is occupied for 15 minutes in an observationinterval of 3 hours. Calculate the traffic carried by the group. (6 Marks)

4 , (a) Obtain total number of cross points for a 3 stage network with N incomingand M outgoing trunks. (8 Marks)

(b) Design a 3 stage switching network for 100 incoming and 400 outgoing trunks.(7 Marks)

(c)Compare any 5 features of single stage and multistage networks. (5 Marks)" ( a ) Explain two different types of gradings. (10 Marks)

( b ) Draw and explain the operation of a time switch. (10 Marks)

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Page No ... 2 EC556. (a) Explain the working ofa T-S-T network. Compare S-T-S and T-S-T networks.

(12 Marks)

(b) Explain SPS in brief. (8 Marks)

7. (a) With relevant sketches explain 30 channel PCM signalling scheme. (10 Marks)(b) Explain in detail the CCITT SS7. (10 Marks)

8. Write short notes on any FO UR of the following : (4X5=20 Marks)i) Side tone reductionii) Register - Translator - Sendorsiii) PBX switchesiv) Overload control in SPCv) In band (VF) Signallingvi) ISDN

** * **

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Page 0... 1 INEW SCHEME ~USN

EC56

Fifth Semester B.E. Degree Examination, January/February 2005Electronics & Communication / TelecommunicationSolid State Devices and Technology

Time: 3 hrs.] [Max.Marks: 100Note: 1. Answer any FIVE full questions.2. Assume missing data if any.

1. (a) What is the cause for bending of energy bands in the P junction diode?Derive an expression for built-in voltage across the junction in terms of dopingdensities. (6 Marks)(b) An abrupt junction PN germanium diode has N A = 1017/cm3 andND = 1015/ cm3 Assuming all impurities are ionized and at T = 300K

determine at equilibrium:i) The built-in voltage Vbiii) The widths of the depletion regionsiii) The electric field at the junction.Intrinsic carrier density of germamum IS 2.17 x 1013/ cm3 and relativepermittivity is 15.8. (8 Marks)

(c) With the I-V characteristics of Germanium, Silicon and Gallium arsenidediodes, discuss the reasons for the difference in the characteristics. (6 Marks)2. (a) Stating the assumptions for ideal diode equation, starting from continuity

equation obtain the hole concentration in the N-region of a P diode.(8 Marks)

(b) What is photolithographic process ? How is it useful in opening a windowfor diffusion? Explain. (7 Marks)(c) Explain, how a required value of resistance is realized in integrated circuits.

(5 Marks)3. (a) Identify the carriers and current components of each of the three terminalcurrents of MPN transistor and sketch its energy band diagram for thermal

equilibrium and saturation. (6 Marks)(b) Why does the collector current decrease when the transistor is operated inthe saturation region? Explain. (4 Marks)(c) A silicon PNP transistor is operating in the active region with VEB =0.668

volts and VCH = -2V. Given that N AE = 4 x 1017/cm3, N DB = 2 x1016/ cm3, N AC =2 x 10H / cm3, WB .=Surn, A =1.8 x 10-4cm2 and lifetime of holes and electrons is 1j.Lsec. Determine at 27C.i) The hole-component of emitter currentii) The hole-component of collector currentiii) The electron-component of emitter currentiv) The electron-component of collector currentv) The recombination-component of the base current

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Page No ... 2 EC56The int.rinsic carrier density for Silicon is 1x 101oem3 and relative perrnitivityis 11.8. (10 Marks)

4. (a) With the Ebers-Moll mold for the PNP transistor, justify the place for everycomponent in one model with respect to the working of the transistor.(7 Marks)

(b) A PNP Silicon BJT has NAP 1018/cm3, NDR 1016/cm3,N;j C =1013/ em.3 , the mettallurgical base width is l.Op,m, and A =37717712.For VEB = O.Svolts and VEe = 5volts, determine at T = 300oK, theeffective width of the neutral base. (6 Marks)

(c) Explain the terms :Early effect, punch through and kirk effect with respect to a bipolar junctiontransistor. (7 Marks)

5. (~) Establishing appropriate relations, explain why BVeBO is larger than EVe EO?(6 Marks)(b) Quantitatively, analyse the transit time of carriers in the base region andturn-on time of BJT. (8 Marks)(c) A base current pulse of 275p,A with a duration of 150nsec is used to turn

on a silicon PNP BJT in a common-emitter configured circuit with Vee =5.0 Volts, RL = 1.2Hl, r > B = Ip,sec, W B = Sum; D P B = 10em:? / sec.Determine at 3000J{, the turn-on time and storage time of the transistor.

(6 Marks)6. (a) Obtain the high frequency small signal equivalent circuit of a bipolar junction

transistor and explain the importance of each to bringout the significance ofthe figure of merit of the transistor. (8 Marks)(b) What is JPET? With constructional details, explain the wotking of FET.

(6 Marks)at 3000K has NA =c) A double - gate N - channel Silicon JFET operating

1019/ cm3, N J) =1016/ em.3 and a =1..5/-Lm. Determinei) the built-in voltageii) the effective channel width for VG = 1 volts and VD =0 voltsiii) the effective channel width for VG =-1 volts and VD =3 volts (6 Marks)

7. (a) With respect to JFET explain : Channel length modulation, breakdown,variation in mobility and temperature effects. (6 Marks)(b) Discuss energy-band diagrams of metal and N-sem.iconductor before contact

and after contact at thermal equilibrium conditions. (8 Marks)(C) A SBD formed on N-Silicon is operating at 300oK. Given MJ) =2xl013 /em3,

the affinity of Silicon is 4.15 eV, and the metal work function is 4.geV.Determinei) the built- in voltageii) the barrior heightiii) the width of the deplct}on layer with Va=0 (6 Marks)

8. (a.) Explain band bending in MOS devices. (7 Marks)(b) Compare the isolation processes used in the fabrication of the BJT and theMOSFET. (7 Marks)(c) How do you mea.sure the parameters of the MOS transister ? Explain.

(6 Marks)

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Page No ... 1 EC/TE5T2USN

ifth Semester B.E. Degree Examination, January/February 2005Electronics & Communication/Telecommunication Engineering

(Old Scheme)Digital Signal Processing

ime: 3 hrs.] [Max.Marks: 100Note: 1. Answer any FIVE full questions.

2. Missing data may suitably be assumed.1. (a) Determine the order & magnitude squared function of the Chebyshev filter

for following specifications.i) Maximum pass band ripple in IdBii) Stop band attenuation is 40 dB for n 2 : 4rad/ sec. (10 Marks)

(b) Design an analog filter with maximally flat response in pass band & an ac-ceptable attenuation of -2dB at 20 radysec. The attenuation in stop bandshould be more than 10dB beyond 30rad/sec. (10 Marks)

2. (a) Compute the DFT of each of the followin~ finite length sequence consideredto be of length Ni) x[n] :- 8 [nJii) x[n] = 8[n-n o];O < no < Niii) x[nJ.." . an (6 Marks)

(b) Compute the 8-point DFT of the sequencex(n ) ={I,l,l,l,l,l,O,O}Sketch its magnitude & phase. (14 Marks)

3. (a) B y means of DFT & IDFT determine the sequence x3(n) corresponding tothe sequences xl(n)&x2(n)

xl(n) ={2,1,2,1}ix2(n) = {1,2,3,4}T

(10 Marks)

(b) Derive the relationship between Z-transform and DFT. (5 Marks)(c) Explain how linear convolution can be obtained using DFT and IDFT.

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Page No ... 2 EC/TE5T24. (a) Develop the 8-point DIT radix-2 FFT algorithm to find the DFT of a sequence

x(n). (10 Marks)(b) Given x(n) '. ~.{a, 1,2, 3}, Find x(k) using DIT - FFT algorithm. (10 Marks)

5. (a) Givenx ( k) = {20,-5.828 - j2.414,0,-0.172 - j0.414,0,-0.172 + j0.414,0,-5.828 + j2.414}

Find x(n) using inverse radix - 2 DIT-FFT algorithm. (10 Marks)(b) What is Bilinear transformation? Obtain the transformation formula for the

Bilinear transformation. (10 Marks)6. (a) Design and realize a digital low-pass butterworth filter using the bilinear

transformation method to satisfy the following characteristics.i) Monotonic stopband & passbandii) -3.01dB at cutoff frequency of 0.57rradiansiii) Magnitude down atleast 15dB at 0.757rradians. (15 Marks)

(b) Explain impulse invariant method of designing a digital filter. (5 Marks)7. (a) Design a symmetric FIR L.P.F whose desired frequency response is given as

H d(w ) = {oe-iWT for 1 W I : : : ; WeotherwiseThe length of the filter should be '7' & We = 1rad/ sample. Use rectangularwindow. (15 Marks)

(b) List the differences between FIR & IIR filters. (5 Marks)8. (a) Obtain direct form - I, direct form - II and parallel realization of the system

given by the following difference equation.y(n) =!y(n -1) - ty(n - 2)+ x(n) + tx(n -1) (14 Marks)

(b) Realize a linear phase FIR filter with the following impulse response. Givethe necessary equation

h ( n) = 8(n) + t8( n - 1) - i8( n - 2) + 8(n - 4) + t8( n - 3). (6 Marks)

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age No ... 1 EC5B3USN

Semester B.E. Degree Examination, January/February 2005Electronics & Communication Engineering, .

(Old Scheme)Telecommunication & Switching[Max.Marks: 100e: 3 hrs.)

Note: Answer any FIVE full questions.

1. (a) Explain the working of a telephone receiver. With the help of a circuitdiagram, show how a small amount of sidetone is coupled into a telephone.

(4+6 Marks){b) List and explain' 8 basic functions of a switching system. (10 Marks)

2. (a) With the help of a schematic diagram, show how a 100 line system can beconfigured using 24, two motion selectors & 100 uniselectors. Show how acall is established between two subscribers. (4+4+2 Marks)

(b) With the help of a schematic diagram, explain how a 100 x 100 switch isimplemented using twenty 10 x 10 cross bar switches.

What does the number on a link signify? (4+4+2 Marks)3. (a) Describe clearly the meaning of pure chance traffic, with the help of necessary

equatiens. Explain how Markov chain process is used to model telephonetraffic. (6+4 Marks)

(b) Derive an equation for the grade of service E of a system having N trunks,when offered 4 Erlangs of traffic for a lost call system, directly and iteratively.

(10 Marks)4. (a) A PBX has three operators on duty and receives 400 calls during busy hour.

Incoming calls enter a queue and are dealt with in order of arrival. The aver-age time taken by an operator to handle a call is 18 second. Call arrivals arePoissonian and operator service times have negative exponential distributioni) What percentage of calls have to wait for an operator to answer them?ii) What is the average delay, for all calls and for those which encounter

delay?iii) What percentage of calls are delayed beyond 30 seconds'? (4+3+3 Marks)

(b) Derive Erlong's delay formula. How is the loss probability calculated for aqueue of finite capacity? (6+4 Marks)

5. (a) What is grading? How do you estimate the traffic capacity of gradings? Whatare the applications of gradings? (3+4+3 Marks)

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Page No ... 2 EC5B3(b) Design a two stage network for connecting 200 incoming trunks to 200 outgo-

ing trunks. When will you have the number of cross points to be minimum?(10 Marks)

6. (a) A T-S-T network has 20 incoming and 20 outgoing PCM highways, eachcarrying 30 channels. Required grade of service is 0.01. Find the trafficcapacity ifi) Connection is required to a particular free channel on a selected outgoing

highway.ii) Connection is required to a particular outgoing highway, but any free

channel can be used. (5+5 Marks)(b) Explain, with necessary diagrams

i) Space switch ii) Time switchiii) S-T-Sswitch

7. (a) List the call processing functions in proper sequence and mention the signif-icance of each function.

(10 Marks)(b) Define availability of the equipment. A stored program control system, has

two central processors, one of which acts as a back-up when the other fails.During the busy hour, total traffic offered is 1000E and average holding timeis 3 minutes. Processing times for calls can be assumed to have an exponentialdistribution, with a mean time of 162ms. Normally, load is shared amongthe two.

i ) Find the percentage of tasks which must queue for processing during the busyhoura) When both processors are operating. b) When one processor is out of service

ii) What happens if the number of calls offered during the busy hour increasesby 25% when one processor is out of service? (2+8=10 Marks)

8. Write short notes on : .,(5X4=20 Marks)i) 30 channel PCM frameii) CCITT signalling system No.7iii) CSMA/CDiv) Evolution of digital switching systems.

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Page No ... 1 EC5T3USN

ifth Semester B.E. Degree ExamiIl,ation, January/February 2005Electronics & Communication Engineering

Old SchemeMicroprocessorTime: 3 hrs.)

Note: 1. Answer any FIVE full questions.[Max.Marks: 100

1. (a) What is a Microprocessor? Explain with diagram, the internal architectureof 8085 microprocessor. (12 Marks)b) Why A D7 - ADo lines of 8085 are multiplexed? Give the necessary diagramto demultiplex AD7 - ADo lines from 8085 microprocessor.

(4 Marks)c) List the status signals in 8085 .Explain their functions.

(4 Marks)2. (a) Define Instruction cycle,machine cycle and T -state, with example.

(8 Marks)b) Write the timing diagram for the following instructions.

i) IN 20Hii) LDA F050H.c) Explain the functions of following 'pins of 8085.

i) RST 7.5ii) HOLDiii) READYiv) SID.

(8 Marks)

(4 Marks)

3. (a) Explain the working of DAA instruction,with an example. (4 Marks)b) How do you classify the instructions of 8085 .based on

i) Number of bytesii) Addressing modeExplain with examples. (8 Marks)

c) Implement a delay loop, using Register pair,to generate a delay of 0.5 seconds.System frequency is 3 MHz. (8 Marks)4. (a) What is a stack? On what principle it works? Is it necessary to initializestack pointer while writing program? Explain with example. (6 Marks)

b) Explain the working of CALL address and RET instructions, in terms ofmachine cycles. (8 Marks)c) Write an ALP to exchange higher and lower nibble often 8 bit numbers stored

from location FOOOH.Make use of subroutine,by passing parameter through

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Page No ... 2 EC5T35. (a) Differentiate between partial decoding and Absolute decoding in case of device(Memory/I/O) selection.Give an example. (8 Marks)

b) Interface 8k byte RAM and 4k byte EPROM to 8085,byabsolute decodingusing 74LS138 decoder.Give the memory map starting at address OOOOHorEPROM. (12 Marks)

6. (a) Differentiate between Memory mapped I/O and I/O mappedL'O.(4 Marks)

b) What isi) Pollingii) Handshaking?Explain with examples. (8 Marks)

c) Interface 7-segment displays to 8085 using ports A and B of 8155 and writea segment of program to display. data bytes at each port. (8 Marks)

7. (a) Write a subroutine to transmit an ASCII charecter using SOD line as one bitoutput port.(ll bits for a .charecter}. (6 Marks)

b) Give the Salient features of 8253 timer.(6 Marks)

c) Explain with internal architecture,the operation of 8259 PIC.(8 Marks)

8. (a) What is DMA transfer? Explain how DMA controller works.(5 Marks)

b) With block diagram, briefly explain the operation of keyboard/display con-troller 8279. .(8 Marks). .

c) Write ALP to initialize 8251 USART and receive data on polled basis giventhe parameters. . .Baud rate factor = 64Character length = 8 bitsNo Rarity check and 1 stop bit.

Assume port addresses 50 H for data and 51 H for control/status. (7 Marks)

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age No ... 1 EC5ELC2USN

Fifth Semester B.E. Degree Examination, January/February 2005Common to EC / TE / CC / EE ) IT / CV / TR / PM / CH

(Old Scheme)Object Oriented Programming

ime: 3 hrs.]Note: 1. Answer any FIVE full questions.2. All questions carry equal marks.

1. (a) Describe briefly the following characteristics.i) Objects ii) Classesiii) Inheritance iv) Stream class hierarchyv) Polymorphism.

(b) Explain the two ways of type conversion using suitable C++ program.(10 Marks)

[Max.Marks : 100

(10 Marks)

2. (a) Mention the specific application and context in which the different loops can, be used. Write a C++ program to compute the cube of numbers from 1 to 10and print out the result using suitable manipulator. Also discuss the visibilityof variables used.

(b) Compare and contrast the if... else statement with a conditional operatorusing a C++ program. (10 Marks)3. (a) Specify a structure syntax with all its components. Give a suitable C++

program alongwith the output to illustrate the concept of structure within astructure. (10 Marks)

(b) Distance between the passing by reference and passing by value. Show witha suitable program how more than one value is returned to the main by thefunction. (10 Marks)

4. (a) Compare and contrast the three storage classes of variables - automatic,external and static. (10 Marks)

(b) With a simple C++ program using a class, explain the terms - object, private,public, inline function, message. (10 Marks)

5. (a) Distinguish between a constructor and a destructor. Develop a program toimplement overloaded constructors and show the corresponding output.

(10 Marks)(b) Combining the concepts of array and class, develop a C++ program to model

a stack of computer memory.6. (a) Illustrate with a suitable C++ program the concept of binary operator

overloading. (10 Marks)(b) Show how the concatenating of strings is achieved in object oriented

programming, using a suitable program. (10 Marks)

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Page No ... 2 EC5ELC27. (a) With an C++ program, demonstrate the concept of multiple inheitance.

(10 Marks)(b) What is a friend function? Use one friend function in C++ program and show

its advantages.8. (a) Write a note on VC++ work bench.

(b) Describe the view menu options of V C++(c) Explain the significance of MFC library.(d) What are the uses of browser?

(5 Marks)(5 Marks)(5 Marks)(5 Marks)

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