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22 fee Ge Za ws ie oO) Veo 311/10) JANUARY 2024 PRINCIPLES OF ELECTRONIC COMMUNICATION Time Aliowed: 2.5 Hours Full marks: 60 Answer to Question No. 1 of Group A must be written in the main answer script. In Question No. 1, out of 2 marks for each MCQ, | mark is allotted for right answer and 1 mark is allotted for correct explanation of the answer. Answer any Five (05) Questions from Group-B. GROUP-A 1. Choose the correct answer from the given alternatives and explain your answer (any ten): 2x10=20 i) The frequency of an electromagnetic wave having wavelength equal to 30m is (a) 10kHz, (b) 1SMHz, (c) 30MHz, (d) 1OMHz. ii) When SSB modulation is compared to DSB modulation, it is found that (a) only their bandwidths are equal, (b) only their powers are equal, (¢) their bandwidths are equal and their powers are equal too, (d) None of these. ili) In AM, over modulation takes place when the modulation index (m) is (a) m =1, (b) m<1, (c) m>1, (d) None of these. tv) Maximum transmission efficiency of amr (d) None of these. v) Nyquist rate for a signa vi) Ifa radio receiver receives all (a) Fidelity, (b) Sensiti (c) Se ude modulation is (a) 50%, (b) 33.33%, (c) 25%, ) 600Hz, (c) 1800Hz, (d) 2400Hz. equencies equally well, then it is said to have high vii) A radio receiver is tuned to 750kHz a frequency would be (a) 1100kHz, (b) 1000k (c) 1170kHz, (d} 1125kHz. ) Which of the following proves that electromagnetic waves are transverse? (a) Diffraction, (b) Reflection, (c) Interference, (d) Polarization. ix) A pre-emphasis circuit provides extra noise immunity by (a) Amplifying the higher audio frequency, (b) Converting the phase modulation to FM, (c) Boosting the bass frequency, (d) Pre-amplifying the entire audio band, x) Ifthe frequency deviation is 75kHz and the modulating frequency is 15kHz, the bandwidth of a commercial FM transmission would be (a) 1S0kHz, (b) 175kHz, (c) 180kHz, (d) 200kHz. xi) Standard Intermediate Frequencies (IFs) for AM receiver and FM receiver are respectively (a) 455kHz and 10.7kHz, (b) 455Hz and 10.7MHz, (c) 45.5kHz and 107Hz, (d) None of these. xii) Anti-side tone circuits in telephone are used to ____ side tone: (a) Reduce, (b) Eliminate, (c) Amplify, (d) None of these. » The two types of PTM are (a) PWM, PAM, (b) PPM, PAM, (c) PPM, PWM, (d) None of ese. xiv) By applying Shannon-Hartley theorem under the condition of Signal Power (S) being equal to Noise Power (N), the relation between Channel Capacity (C) in bits per second and ao in Hz is given by (a) B>C, (b) B=C, (c) B siemal having an amplitude of 25 vo. : ic equations for the modu jodulation index and per cent modulation, ; °. ing signal and ¢ (i) Write the A rave? the sideband frequencies in the modulated wave ox aan \M s is the Sampling Theorem. (b) Describe briefly with diagre 4. (@) Give one example of each of simplex, half-duplex, and full-duplex transmission 1 es (6) Define the terms as applied in communication in brie trum, § \ to-Noise ratio, Fourier series, Modulation, and Line-codir g. 5] | §. Give the full forms of the following: DSB, AGC, PLL, DTMF PPM, ISI, A ar \ 6, Describe ad working principle of any one of the following with a neatly drawr (1) AM Super heterodyne receiver, (iti) FM broadcast transmitter. [8] propagation? (b) Explain the t ae . mi ems Critical Bre. =e ual Height with reference to Sky Wave Propagation Nical F Tequency, Skip \ [2+6] \ 8. (a) Show the elements of (b) State the Shannon Hartley the system y a Nes ystem with a neatly drawn block diagram [S+3] 9. (a) Describe the Operation of a si Distinguish between Space Divisio, udset with a simple block € Division Sw itching. diagram (b) Switching anc [ $s osed loop gain will xv) The open loop gain of an amplifier ns200 If neg "be (a) 200 (b) 40.12 (c) 4.878 (d) 2.2 GROUP-B or ind the Stability fe 2) Define stability factor and Q point 3) Compare the characteristics of CB, CE, and CC configuration. Find the rel neat sketch 4) Define Filter circuit. Explain the circuit diagram of induc 5) Compare different types of coupling in amplifier. Draw t i model of common base transisto. 6) Compare the characteristics of Class A, Class B, and Class C power amplifier. Briefly describe the Emitter follower c with suitable diagram ae 7) Briefly describe the operation and application of Uni- Junction Transistor with suitable ¢ Draw the symbol of N-Channel JFET and MOSFET. > 543 8) Briefly describe the Operations of voltage regulator circu Write the difference between Zener breakdown and avalanche breakdown 544 5+3 9) Define Barkhausen criteria -Briefly describ with suitable diagram, he effect of negative feedback on gain stability and bandwidth xiii. JANUARY 2 Dicrrat ELectRONICS d: 2.5 Hours Pill Marks: ft Answer to Question No. bo be written in the answer seript, In Question No. t, marks is allotted for right answer and 1m pr correct explanatio 6 from Group: h MCQ, of the answer. =20 1 the given alternatives and explain your answe ry ten): 2x Choose the correct answer Which of the following is an invalid BCD? a)l001 _b) 0111 1010 d) O11 Which value is considered for a “don’t care” condition a)O b)l c) Either Oor 1 d) Any number except 0 or | ta be taken out of a shift register b) Use the Q output of the last FF. d) Use the Q output of each FF How can parallel d a) Use the Q output of the first FF ¢) Tie ull of the Q outputs tog ether or are he a)2 b)4 c)6 ds Which one i a) Multiplexer coder d) Counter ‘What is the difference between cont logic and sequential logic rises, sequential circuits ate triggered by timing a) Combinational circuits are ng pulses. b) Combinational and seque! tial ¢ c) Neither circuit triggered by d) None of the above. ed by timing pt valid BCD ? e)LOLO Which of the folle a)1001 boll s reflected Which one of the f a) 8421 code b) Exces-3 code d) ASCIl code Convert the number (95),0 to its Hexadee a)5F b)SE 5A What type of shift register only the leftmost and rightmost flip flops? a) Serial-in serial-out shift register b) Serial-in parallel-out shift regisier d) Parallel-in Parallel-out shift regist has access t ‘A multiplexer is also called as a a) Coder b) Parallel adder ¢) Data selector d) NOR gate d and internal shift | serial loa What is a shift register that will accept a parallel input, or 4 bidirectio features, called? a) tri-state b) end around c) universal 4) conyersion In Boolean Algebra At+l= a) 1 b)0 cA d) None of these s 56/701 a 2 See 71a Vary S60) nsw, er red ig 4 ‘pts py, Fans, lis Time Allowed: 2.5 Hours JANUARY 2024 S11/4(N) ELecTRIc CincuITs AND NETWoRK Full Marks; 60 newer to Question No, Gr ‘i At Q ‘0, L of Group A must be written in the main answer seript. In Question No. 1, out of 2 marks for each MCI - if : for each MEQ, 1 marks is allotted for right answer and 1 marks is allotted for 1, Choose the corre i) ii) v) vi) vii) viii) ix) x) xi) xii) Correct explanation of the answer. Answer y Five (05) Questions from Group-B. GROUP-A swer from he giver ef ives and explain ye n): 2x10=20 answer (any The junction where two or more network eleme (a) loop (b) node ned together is called a (d) closed path Thevenin’s theorem and Norton’s the (a) nonlinear network _(b) unilatei (c) linear and bilateral network —( n are able to = network ear ani unilateral network onnected in delta network. The value of each resistance in the 82 (b)22 (©) 202 (d) 62 6 Qeach a star network is- (a) ee resist equivale nces: ent 1 in series. The equiy ) 10F ¢ connect (c) ISE ( Two capacitors capaci nee is resonance is (c) Less than 1 ‘The current thi (a) minitr (d) 1 ess than maximum es and b branches are ~ n-1 (d)btn The number of (a) co-tree Is (b) links (c) twigs —(a)l °(b)2 ©3 4) 4 1s are present in x Networ How many shu Ifa T-Network is symmetrica then the values (b) Shunt arms not equal (¢) Series (d) Ser arms not equal arms eq\ (a) Shunt arms equi For Two-port network, Y- parameters are known as (a) Hybrid Parameters (b) Transmission Parameters (c) Open-Circuit | pedance Parameters (d) Short-Cireuit Admittance Paramet An ideal filter should have (a) Zero attenuation in the pass band (b) Zero auation in the attenviation band > attenuation in the attenuation band (c) Infinite attenuation in the pass band (d) Infinite In active filter circuits, inductances are av ded mainly because they (a) are always, associated with some resistance (b) are bulky and uns' able for min (c) are non-linear in nature (d) saturate quickly ive network ~ (b) R-L network. (c) R-C network (d) L-€ network. ‘An attenuator is a- (a) Res The purpose of an attenuator is to ~ (a) Increase signal strength (b) Decrease reflections (c) Decrease value of signal strength (d) Provide impedance matching If Zoc = 120 Q and Zse= 30.2, the characteristic impedance is ~ (a) 302 (b) 60.2 (c) 120 2 (d) 150.2 J 57/671 unter is ) None ¢ SUPE (©) (by LPF (a) Attenuator sion line W orks 88 line (b) Stand Silt paris Wav a Wave Ratio meant by SWR of Wave Receiver ek is pacitance (b) I sanstorm of a unit impulse xix) Laplace x Inverse Laplace transform of i(s-a)is—(@)S ») etse Lapla xxi) aplace transform method enables one to (b) the steady state only at state only both transient and steady states insient state provided s xxii) A capacitor at (= 0+ with i Voltage source al charge Qo a ) current source (c) open c ction ‘Aramp function (b) An impulse function (c) Mos function (4) A sinusoidal fun xxiv) The Fourier series expat (a) Sine terms (b. cosine terms: xxv) xxvi) ier series W ficients (¢ a) State Kirchhoff’s current 1 Pind the value oe ment! Which conserva which maxi: maximumn power transfered in the eiro Mn principle it obey? 1 power is transi shown in figure ol Ted and also caleutate the valve a 1 Shas ee ov te erm RL a) Define a tree of a graph of a network, Mention 5) elite the number of posible es of given graph wn PPR OF “neg ) How the values ofthe elements By can bs computed for «'Tie-Set nq ered -Sot Matrix? For the circuit shown in Figure, find Z-purameters. te ‘ deavate vii viii Answer to Q No. 1, out marks is JANUARY 20. pression in $8) 677 th all elements as zero in C pro; = (0; int array[$] = fa, b, e}5 d, Allofthen ed : ~ at \arren if the following C code is executed? #inelude int main) { int main= 3; printi("%d", main); use 4 compile-time error use @ run-time error ‘perience infinite looping Tt will run without any error and prints 3 How can a pointer variable be declared in C that can store the address of an integer? a. int ptr; b. int *pir; ¢. ptrint; do prr*int; Which feature of OOP indicates code reusability? a. Abstraction b. Inheritance ¢. Polymorphism d. Encapsulation GROUP-B y is C called Mid-level pro; ing |: i ‘ope unsigned at programming language? What is the range of values that can be: : -(b) Explain the Memory Hierarchy in a computer system, ayy. 8 Peace ic, SEP oe ae RINE DeEge arty, Be? Sx , Mawes. Dove SII/I(N) March 2023 Total OS Mo principles OF ELECTRONIC COMMUNICATION ‘ll Marks: 60 Time Allowed: 2.5 Hours Answer to Question No.lof Group—A is compulsory and to be answered first. This answer is to be made in separate loose seript(s) provided for the purpose. Maximum time allowed is 30 minutes, after which the loose answer scripts will be collected and fresh answer scripts for answering the remaining part of the question will be provided. On early submission of answer scripts of Question No. 1, a student will get the remaining script earlier. Answer any five questions from Group B sroup-A 1. Choose the correct answer from the given alternatives (any twenty) i) The wavelength of an electromagnetic wave signal is 40 m. The frequency of th (a) 7.SMHz, (b) 75 kHz, (c) 7.5 kHz, (d) 7SMHz ii) Modulation is needed to a) increase the transmission length, b) gain an ability to m signals, c) use a shorter aerial length, d) all of the above. i) The process of transmitting two or more signal over a common channel is called (a) Modulation (b) Multiplexing (c) detection (d) telemetry. iv) The number of sidebands produced by amplitude modulation in addition to the carrier is a) 3, b) 4,c) 2, d)1 v) Which one of the followi (a) AM-SSB, (b) AM-DSB, (c) FM, (d) AM yi) An FM signal is represented as v(t)= 12 cos(6 x 10°t + 5 sin 1250 t) . The modulation index is (a) 12 (b) 6 (c) 5 (d) 1250. vii) Commercial radio or TV broadcasting is an example of a) simplex, b) half-duplex, ¢) full- & ES 3 B modulation technique has minimum noise effect duplex, d) none of the above, communication system viii) If a modulating wave is first integrated and then phase modulated, the resultant waveform a) FM wave, b) PM wave, c) AM wave, d) none of the above. ix) The function of a radio receiver is to a) Intercept the incoming modulated signal, b) Select the desired signal, c) Amplify the selected RF signal, d) All of the above. x) The total sideband power is what percentage of the carrier power for 100% modulation? a) 25%, b) 50%. c) 75%, d) 100%... xi) If the power of FM signal is compared to the power of the unmodulated carrier: a) FM signal power >unmodulated carrier power, b) FM signal power = unmodulated carrier power, ¢) FM signal power < unmodulated carrier power, d) None of the above. xil) Maximum transmission efficiency of amplitude modulation is a) 25%, b) 50%, c) 33.33%, d) 80%, xiii) A balanced modulator produces as its output a) SSB-SC, b) AM-FC, c) DSB-SC, d) none of the above xiv) When microwave signals follow the curvature of the earth surface is called (a) the early effect (b) ducting (c) tropospheric scatter (d) ionosphere reflection, *) The Bast rate for a signal of S00 Hz is (a) 1200Hz (b) SOOHz (c) 1000 Hz (d) 2000 Hz. xvi) on x pia : sae ‘3 AM wayeform has the shape of the modulating signal A Carrier, c) trace, d) envelope. xvil) Tropospheric scatter is used with fr ies i fc i Y Baia equencies in the following range: a) HF, b) UHF, c) VHE, only one of the followin, goes ve, i underZ0e" e spac i) WI agnetic wave travels 1 viii) When an electromagnetic wave tavels Mion + i prssed in DTME dialing a) attenuation, b) reflectic 0) oak Thelkey marked 2 eee p77 He ae ape produced when 7, d) 852 4 —_ xix) What two sine waves a Sa (B00 He 9) 70.81 w 1330 6) public swi ch true network, 2) 697 and 1336 Hz, b) 770 and 1207 work. : mm mane for (a) Process switehed telephone ne ‘telephone network wenciaat Tw a aa. . vitehe encies is xx) PSTN stands Pn awitclied ‘osel 46 ' s) Public serial telephone network, (4) Mam hers on closely ¢ io serial teley " te one 5) gain, d) selectiv! ich a PLL will yce band PAI ver to sep xxi) The ability of a ree called a) fidelity, b) sensitivity, ¢) xxii) The range of frequencies whit a) capture range, b) lock range, ¢) aeceP ' TM are a) pwM and ty. ack input signa d) none of the above ppM and PWM, ariation | ov ) PPM, and PAM xxii) The two types of d) None of the above xxiv) Bye diagram a) is used to study IST, 6 ay be observed 0D vesembles the shape of an observed OF CRO, ) res bles the E s (b) 500 bps (¢) eye. a) the bit rate is (a) Tkby which a bit lasts for 0.001 sec xxv) A signal i (a) LOkbps Group-B ic signal presentation of a peric he iigonometric form of Fourier series re ple block ¢ he elements of basic communica system using a 2. a) White 6) Show 1e function of each block in brief. expl 3. a) Define modulation. Compare and contrast AM, DSB-SC, and SSB in term of their bandwidths ¢) Derive an expression for the total power of AM wave in terms of carr modulation index. 3 a) What are the two typés of angle modulation? > b) Find the modulating frequency, the maximum deviation, a d power dissipation in a ohm res istor by an FM Wave given by the voltage equation: ¥= 10 sin(600000000r + 5 sin 1200t). Draw a block diagram of FM broadcast transmit operation in brief T (Armstrong system) and e: a 8) What do you mean by intermediate frequency? 3 b) Bi exp; ) Bnefly explain with a neat block diagram the Working Principle of supe on the role performed by he m i or super hete 7. a) Describe briefly the va : mbe briefly the various strata of receiver mai emphasizi rodyne radio b) Why is sky-wave Propagation a) State the samy ling theorem. 4) Describe how PWM js ve Je S n M is genera appropri g ‘PPropriat Circuit dia 2 aa block diagram of 4 telephone handset ~ < e ideas of ‘Low . ~ eas Of “Local Loop’ and ‘Sy Htch Hook’ in by ref, a 10, < on Shannon-Hartley theorem. Taw Neatly the wavef ay orms unipolar RZ. UNipolar NRZ > and AMT § = OF the di - Bital Signa] Onda equivalent cireuit for Common er 6, Draw the! ybrid mplifier gemenits of T ansformer-coupled en a voltage amplifier and a power amplifier. With the help > Distinguish betwe ass AB power amplifier. Wri dvantages of class B push A. ClassB, ClassC and Cl That? tor. Briefly describe effe edance. e feedback on gi 246-8 e Barkhausen criteria of Osct nd put i ram. Draw the cir 5+3=8 suitable circuit d c) d) UST rela oscil fo’ ) Name the ay? 4 2 plaid the , De xiv) — A universal shift register can shift bits (b) from ea left ite... es (a) from left to rip) (dy none of the » Dis (c) both from Teft to right ond rig! — aus n xv) A ring counter with 5 flip Nops will have (e) 32 states (d) inf A (n) § states (b) 10 states we weer 40. a) Static and (d) NOR gate ‘ 5 stot {a) Coder) Parallel adder (c) Data selector The number of Select Lines in a 16:1 Multiplexe y1 (b)2 (a (a4 K HIGH, the ov For a positive edge-triggered J-K flip-flop with both HIGH. : (b) Set (ce) Reset (d) Note clock gor (a) Toggle ris shift regist (b) ring counter (d) serial to serial data conversion. lel data conversion When the input J-K=1, PRE=], CLR=0 J-K flip flop will (a)set (b)reset (c) not change (d) toggle How many flip-flops are required to make 2 MOD-10 binary counter? fa)3 (b)4 (c)5 (a6 {a | multiplexer can be connected to form mult ) Two 16:1 multiplexers and one (a) 16:1 multiplexor (b) 32:1 multiplexor (c) 64:1 multiplexor (d lexor The digital logic family which has minimum power dissipation is (a)TTL (b)RTL (c)DTL (d) CMOS. ital. The resolution is 4xiv) A 12 bit ADC is used to convert analog voltage of 0 to 10V into (2)244mV (6) 244mV (ce) 12 V (d) none of the above xxv) Time delay of a TTL stand. (a) 180.ns (b) 5¢ family is about (c)18ns (d) 3 ns, Group B a) Express the following Boolean ex; y ig Boolean express: 9 Canonical forn TE ae nonical forn, b) State De Morgan’s 1" and 2m! theorem, 41(2+2) a) Minimize the Bool ean expression using Kama igh map. F(A,B,C.D’ = =m (3,4,5,6. pI F »€,D) = 14,9,6,7, b) Implement the following function using multiplexers, F(A 1,13,15) 11,13,1 B.C,D) =Em (0,3,10,11,12,13.15) ard a peien amod 10 counter raw the circuits of a 4-bit Ring o it Ring counter and a Twisted Ring counter. Give the truth tables. Hohe a) Write down the tra P ith table of'a F; A 5) What are the diff: ull Adder and find erences betwe, Out the expressions of Si a arry * Setween a synchronous Counter and an cpap ee ; 543 a) Give the logic diagra - gram of a clocked R-S fj b) How a J-K flip-flop is Converted into a T ape Discuss its Working principle, flop? Write down the truth table ofa T flip-flop, 5+3 if the >. a) Name th e four basic types of shift registers.Draw the block ration and use ofa TTL NAND gate g. a) Explain the of 1 noise margin with reference to differ b) Discuss the power dissipation ve Approximation ADC. 9. a) Explain the working principle of a Suc 10. Write short note on the following’ M._ b) Priority encoder a) Static and Dynamic RA! ns and explain ent logic families: 
