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# 6th Semester Electronic and Communication Engineering (2012-June) Question Papers

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• 1. USN 06E,C61 Sixth Semester B.E. Degree Examination, Jlune 2012 Digital Gommunication Time: 3 hrs. Max - Marks:100 Note: Answer FIVE full questions, selecting at least TWO questions from each part. PART-A I a. With a neat block diagram, explain the operations of digital communication system. Explain the functioning of each block. (06 Marks) b. A signal g(t) = l0 cos (20nt) cos (200nt) is sampled at the rate of250 samples/sec.EA i) Sketch the spectrum ofthe sampled signal ii) Specify the cut-off ideal reconstruction filter so as to recover g(t) from g,(t) iii) Specify the Nyquist rate for the signal g(t). (08 Marks) c. What is flat-top sampling? Derive an expression for the flat-top sampled signal. (06 Marks) 2a. Show that the signal to quantization noise power ratio of a uniform quantizer is p [ :p l-.- {08Marks) -,,1,12".l oa Lc;_ h. For a binary PCM signal, determine L if the compression parameter p = 100 and the minimum [SNR]0. ae = 45 dB. Determine the [SNR]6. dB with this value of L. (06 Marks).s.l c. With a neat block diagram and waveforrn, explain time division multiplexing. (06 Marks) 3a. With a neat block diagram, explain delta modulator transmitter and receiveq and alsod,- modulation. explain the errors in delta (08 Marks)6cd b. Obtain the power spectral density of NRZ polar format and draw normalized diagram. (08 Marks) c. Compare DM with DPCM. (04 Marks)!6 4a. Derive the Nyquist criterion for distortionless baseband binary transmission. (08 Marks).E 9p b. What is eye pattem? Explain in detail. (06 Marks) c. With a neat filter structure, explain the concept ofadaptive equalization process. (06 Marks) PART-B-l .i 5a. List the important requirements of passband transmission scheme. (04 Marks)z b. Estimate the power spectral density of a BPSK signal from Fourier transform of basic NRZ pulse. (12 Marks) C. What are the advantages of MSK over QPSK? (04 Marks) l of 2
• 2. - 06EC61 6a. Explain geometric interpretation of signals. (08 Marks) b. Three signals Sr(t), S2(t) and S:(0 are shown in Fig.Q6(b). Apply Gram-Schmidr procedure to obtain an orthonormal basis for the signals. Express signals S1(t), Sdt) and S3(t) in terms oforthonormal basis functions. Also give the signal constellation diagram. (12 Marks) Srl4) s*t*) Fig.Q6(b) 7 a. Show that the probability ofbit error of a matched filter receiver is given by: ,t. P. = I erfc. " 2 ilL . (12 Marks) llN, b. Draw and explain the block diagram of conelation receiver. (0E Ma*s) 8 a. What is spread spectrum technique? Explain the working of direct sequence spread spectrum transmitter and receiver. (10 Marks) b. Explain the properties ofPN sequence. (06 Marks) c. Compare slow and fast frequency Hopping. (M Marks) {. ,.! 2of2
• 3. IIt 1",vaI USN 06E.C62 Sixth Semester B.E. Degree Examination, June 2Ol2 Microprocessors Time: 3 hrs. Max. Marks:100 * "r., " ", ", {{: #::,1: r:i::: ::,:;fr1,,. ai = PART - A 9 I a. What is a microprocessor? What are the components required to build a minimum o. microcompuigr system? Explain with a neat diagram. (06 Marks) i b. What are the roles of each element in the BIU of 8086 CPU? Explain with a neat diagram. !?. How is the 20-bit physical address for memory generated? Explain with an example. L ( l0 Marks) f-i_ !a! c. What is the minimum size and maximum size of an instruction in 8086? Explain with examples. (04 Marks) *- ll 2 a. Explain the importance of each field in Byte-l and Byte-2 of the 8086 instruction template. Y., If the 6-bit op-code for ADD instruction is "000000" then formulate the op{ode/s for ()tr "ADD AX, CX" insfiuction. (07 Marks) 3e b. What are the pseudo codes? Explain the following directives with examples: i) ENDP ii) EXTRN iii) GLOBAL iv) PROC. (07 Marks) 9.s c. Write the single instruction equivalent for the following program segments if available and .Jo justify your answer; assume that these program segments are stafting fiom memory location boc FFFF0h and 8086 is resetjust before execution. €E i)FFFFo: MovCL, lOh iitFFFFO: I-o^l,tI: A_,.-O AX.BX xcHG MOVBX. AXiS -.4 AX.CL RoR ADDAx.BFi7 J,- XCHGAX,BX XCHGAX,EXT Mad<s) 7v =ia T:- 3 a. What is a procedure? What are its advantages? l): ,;6 V Marks) ,t! b. Write a 8086 procedure to conven a packed BCD number in AL to in AX. !o (0,6 Marks) b!o c. How do you invoke near procedures and far procedures in 8086? What are the methods available for palameter passing in procedures? (06 Marks) != 9- d. What makes a MACRO facility to be prefered over a procedure in a program development? (04 Marks) oi -i ci a. What is the response of 8086 pp when interrupted? Explain clearly. (0,6 Marks) z b. Explain the interrupt system of 8086 CPU with allthe sources of interrupts. (08 Marks) s c. How many string instructions are available in 8086 instruction set? Explain briefly. E (06 Marks) 1of 2
• 4. o6EC62 PART-B5a. Why interfacing is required? Explain. (03 Marks) b. What do you mean by key-debouncing? Explain briefly hardware debouncing and software debouncing methods. (05 Marks.) c. lnterface a 4x4 keypad to 8086 cPU and write a program to identifu any key pressed. write necessary comments. (12 Ma*s)6 a. What are the functions of the following 8087 instructions? Explain. i) FBSTP TAX ii ) FSUBR Dr, Sr iii) FXAM iv) FLDL2E (06 Marks) b. Interface 8087 NDP to 8086 CPU; indicate all critical signal connections. (O7 Marks) c. write a program to compute roots of a quadratic equation using 8087 instructions. (07 Marks)ta- What is maximum mode of operation for 8086 CpU means? Show all necessary arrangements for 8086 maximum mode. (07 Marks) b. Write a program using 8086 instruction to check whether pCI bus extension is available using BIOS. (06 Marks) c. For an USB in personal compuEr give: i) Pin configuration ii) Two cRC polynomials iii) Token packet & data packet. (07 Marks)8 a. Using a block diagram, briefly indicate different signal groups on 80386 processor. (10 Marks) b. With a neat block diagram, explain the Pentium architecture and features. (10 Marks) 2of2