the operation of a DPSK system with the help of a block diagram. (b) Compare different modulation/demodulation schemes used in digital pass band transmission systems. 8 (a) Compare

Code: 9A04601

B.Tech III Year II Semester (R09) Supplementary Examinations December/January 2014/2015DIGITAL COMMUNICATIONS

(Electronics and Communication Engineering)

Time: 3 hours Max Marks: 70 Answer any FIVE questions

All questions carry equal marks *****

*****

1 (a) Explain in detail about non-uniform quantization. (b) What is the disadvantage of uniform quantization over the non-uniform quantization?

2 (a) Explain T-1 carrier system used for long distance data transmission with special reference to the companding details and bit-rates.

(b) A Delta modulator is used to encode speech signal band-limited to 3 kHz with samplingfrequency 100 kHz. For ±1 volt peak signal voltage, find (i) minimum step size to avoid slopeoverloading. (ii) signal to quantization noise ratio, if speech is assumed to have non-uniformprobability density function (PDF).

3 (a) What is meant by ISI? Explain how it differs from cross talk in the PAM. (b) What is the process to suppress (or) eliminate intersymbol interference? Explain in detail.(c) An analog signal is PCM formatted and transmitted using binary waveforms over a channel that

is band limited to 200 kHz. Assume that 32 quantization levels are used and that the overallequivalent transfer function is of the raised cosine type with roll off of 0.45. Find: (i) Themaximum bit rate that can be used by this system without introducing ISI. (ii) The maximumbandwidth of the original analog signal that can be accommodated with these parameters.

4 (a) What are optimal filters? Derive the transfer function of optimum filter.(b) What is the difference between base band transmission and band pass transmission?

Distinguish them.

5 Draw and explain the block diagram of ARQ systems in detail.

6 (a) Explain the following terms: (i) Coding efficiency. (ii) Source coding.(b) Consider the AWGN channel with S/N = 104. Find the maximum rate for reliable transmission

when B = 1 kHz, 10 kHz and 100 kHz.

7 (a) Explain the operation of a DPSK system with the help of a block diagram.(b) Compare different modulation/demodulation schemes used in digital pass band transmission

systems.

8 (a) Compare and contrast between binary signaling scheme and M-ary signaling scheme.(b) Explain about demodulation of QAM.

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Code: 9A04602

B.Tech III Year II Semester (R09) Supplementary Examinations December/January 2014/2015MICROPROCESSORS & MICROCONTROLLERS

(Common to EEE, ECE, CSE, EIE and E.Con.E)



*****

1 (a) Explain memory addressing modes of 8086. Give an example for each addressing mode.(b) What is the purpose of Trap flag? Discuss how debugging feature is provided with the help

of Trap flag in 8086.

2 Write an ALP in 8086 to find the largest and smallest of a set of 8-bit numbers.

3 (a) Explain need and importance of DMA.(b) Discuss about static RAM and EPROM with reference to 8086.

4 (a) What are the different modes of 8255?(b) Explain the 8255 interfacing to 8086 in mode 0.

5 (a) Explain about USB with necessary example and analysis.(b) Give the voltage levels of RS232. Give two features of RS232.

6 With a neat diagram explain the working principle of 8253.

7 (a) Write a program to load accumulator, DPH and DPL using 8051.(b) What is subroutine or procedure?

8 (a) Explain the addressing modes of MCS-96.(b) Clearly explain the Instruction set of MCS-96.


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Code: 9A04603

B.Tech III Year II Semester (R09) Supplementary Examinations December/January 2014/2015DIGITAL SIGNAL PROCESSING

(Common to EIE, E.Con.E, ECC and ECE)



*****

1 Determine the sequence corresponding to following frequency domain representation.

X(ejω) = 1 ω≤W or -W ≤ ω ≤ W

= 0 W ≤ ω ≤

2 (a) State and prove following properties of DFT:(i) Linearity. (ii) Circular shift.

(b) Give the comparison between DTFT and DFT.

3 (a) Find the 4-point real sequence x(n) if its 4-point DFT samples are: X(0) = 6, X(1) = -2+j2, X(2)= -2. Use DIF-FFT algorithm.

(b) Find the 4-point DFT of the sequence, x(n) = sin(n /4) using DIF – FFT algorithm.

4 Consider an LTI system, initially at rest, described by the difference equation: y(n) = (1/4) y(n-2) + x(n)

(i) Determine the impulse response of the system.(ii) Realize the system in Direct form-II and in Cascade form.

5 Determine the H(z) for a Butter worth filter satisfying following frequency specifications

0.95 ≤H(ejω) ≥ 1 0 ≤ ω ≤ π/2

H(ejω) ≥ 0.15 3π/4 ≤ ω ≤ π

Assume T = 1 Sec. Use Impulse Invariant method.

6 (a) Compare features of different windowing functions. (b) Justify that FIR filter is linear phase filter.

7 Consider x(n) = tri (n/4).Sketch the following signals and describe how they differ.(i) x(2n/3), using zero interpolation followed by decimation.(ii) x(2n/3), using step interpolation followed by decimation.

8 (a) Explain commonly used time domain operations in musical sound processing. (b) Write short notes on coding redundancy.


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Code: 9A04604

B.Tech III Year II Semester (R09) Supplementary Examinations December/January 2014/2015ELECTRONIC MEASUREMENTS & INSTRUMENTATION




*****

1 (a) Explain the methods of obtaining a DC instrument and AC instrument from a basic meter. (b) A basic D’ Arsonval movement with a full scale deflection of 40 µA and internal resistance

of 400 Ω is used as a voltmeter. Determine the value of the multiplier resistance needed tomeasure a voltage range of 0-10 V.

2 (a) What are audio frequency (A.F) signal generators? (b) Explain the working of Wien bridge oscillator with a neat sketch.

3 (a) Define a distortion analyzer. (b) State the working principle of a distortion analyzer.

4 (a) Differentiate active probes and passive probes. (b) What are attenuators? What is a compensated RC alternator?

5 (a) Discuss the advantages and disadvantages of analog and digital type of oscilloscope. (b) Describe an overview of applications of a CRO.

6 With neat sketch explain the measurement of unknown inductance by using Hay’s bridge.What are the advantages and limitations of it?

7 (a) Write a short note on pressure transducers. (b) Explain the working principle of pyrometer.

8 Give the constructional features of X-Y recorders. State its applications.


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Code: 9A04605

B.Tech III Year II Semester (R09) Supplementary Examinations December/January 2014/2015VLSI DESIGN

(Common to ECE, EIE and E.Con.E)



*****

1 With neat sketches explain oxidation process in IC fabrication.

2 (a) Write clearly about design hierarchy.(b) Explain the concepts of regularity, modularity and locality.

3 Draw the CMOS NOR gate & its physical layout with stick diagram.

4 (a) What are the two basic forms of interconnection trees? What are the two wiring models of aninterconnect? Explain them.

(b) Estimate the interconnect delay using Van Ginneken algorithm.

5 (a) Implement a 8-bit comparator using 4-bit comparators and other interfacing requirements.(b) With the help of logic diagram explain the working of 4-bit comparator.

6 Implement the following using gate logic, switch logic and PLA in NMOS:(i) 4:1 multiplexer. (ii) 4-bit comparator. (iii) 8-bit parity generator.

7 (a) Explain register transfer level synthesis.(b) With the help of an example explain how designing is optimized at register transfer level.

8 (a) Explain about IDDQ (VDD supply current quiescent) testing for bridging faults?(b) Explain how a Pseudo random sequence generator and a signature analyzer is used to test an

8-input combinational circuit.


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Code: 9A04606

B.Tech III Year II Semester (R09) Supplementary Examinations December/January 2014/2015MICROWAVE ENGINEERING




*****

1 The dominant mode TE10 is propagated in a rectangular waveguide of dimensions a = 6 cm and b = 4 cm. The distance between a maximum and a minimum is 4.47 cm. Determine the signal frequency of the dominant mode.

2 (a) Explain the differences between strip line and microstrip line.(b) Draw the circular resonator cavity diagram and derive equation for resonator cavity.

3 Draw the E-plane Tee diagram, equivalent circuit and field diagram. Explain how power iscoupled into port 3.

4 Show that the S-matrix of a directional coupler is given by:

[ ]

=

0000

0000

αβαβ

βαβα

jj

jj

s

Where 122 =+ βα

5 (a) Explain the gain bandwidth product limitation & transit angle effects in conventional tubes at microwave frequencies.

(b) A reflex klystron operates under the following conditions:V0 = 900 V, L = 1 mm, Rsh = 25 kΩ, e/m = 1.759 × 1011 (MKS system), fr = 9 GHz. The tubeis oscillating at fr at the peak of n = 2 mode or 1¾ mode. Assume that the transit timethrough the gap & beam loading can be neglected.(i) Find the value of repeller voltage Vr.(ii) Find the D.C current necessary to give a microwave gap voltage of 100 V.(iii) What is the electronic efficiency under this condition?

6 (a) What is CFA? State the applications of CFA. (b) Explain the operation of TWT amplifier with a neat diagram.

7 (a) Write down basic requirements for two-valley theory of Gunn diode. Explain. (b) What is the main idea behind obtaining negative resistance in a Gunn diode?

8 (a) Explain the method to measure VSWR and reflection co-efficient. (b) Describe the measurement of impedance using slotted line and Smith chart.


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Documents

the operation of a DPSK system with the help of a block diagram. (b) Compare different modulation/demodulation schemes used in digital pass band transmission systems. 8 (a) Compare