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Paper / Subject Code: 51424 / Principle of Communication

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June 12, 2024 02:30 pm - 05:30 pm 1T01233 - S.E.(Information Technology Engineering)(SEM-III)

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(Choice Base Credit Grading System ) (R- 19) (C Scheme) / 51424 - Principle of Communication

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QP CODE: 10056409

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Time: 3 Hours Marks: 80

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N.B. (1). Question No.1 is compulsory.

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(2). Out of remaining attempt any three.

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(3). Assume & mention suitable data wherever required.

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(4). Figures to right indicates full marks.

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Q.1. Solve any four [20]

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a). The signal power & noise power measured at the input of an amplifier are 150 µw & 1.5 µw

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respectively. If the signal power at the o/p is 1.5w and noise power is 40mw, calculate amplifier
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noise factor & noise figure.
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b). Calculate the percentage power saving for DSB-SC signal for percentage modulation

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of a) 100 % b) 50 %
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c). Compare PAM, PWM & PPM

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d). State advantages of digital transmission.

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e). Explain in brief different types of communication channels.

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f). Explain the principle of reflection and refraction.

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Q.2 a) Explain FDM with neat block diagram . [10]

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b). State and prove the following properties of Fourier transform with example
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i) Convolution in time domain ii) Time scaling [10]

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Q.3. a) In an AM radio receiver, loaded Q of an antenna circuit at the input to the mixer
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Is 100.if the intermediate frequency is 455 KHz. calculate the image frequency &
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Its rejection at 1 MHz . [10]

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b).With the help of neat circuit diagram explain varactor diode method of FM Generation
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[10]
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56409
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X525Y13A008X525Y13A008X525Y13A008X525Y13A008
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 08 3A 5Y 8X A0
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00 Y1 52 08 13 25
8X 3A 5Y X5 A0 Y1
52 00 13 25 08 3A
5Y 8X A0 Y1 X5 00
13 52 08 3A 25 8X
5Y Y1

Q6.
Q.5
Q.4
A0 X5 00 52
52 08 13 25 8X 3A 5Y
5Y A0 00

56409
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13 25 08 3A 5Y 8X A0
A0 Y1 X5 00 13 52 08
08 3A 25 8X A0 5Y X5
X5 00 Y1 52 08 13 25
13 25 8X 3A 5Y X5 A0 Y1

(4) TDM
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08 3A 5Y 8X A0 Y1 X5 00
X5 00 13 52 08 3A 25 8

waveforms
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08 3A 5Y X5 A0 Y1 00 Y1
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25 5Y
(v) Skip Zone
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(i) virtual height

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3. Delta modulation
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1. Need of modulation
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(1) Aliasing or fold over error

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4. Friss Formula of noise.

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2. Role of balance modulator

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1. Unipolar RZ 2. Polar RZ 3. AMI

b) . Write short note on following (any two)

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(iii) maximum usable frequency (MUF)

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a). With reference to sky wave propagation explain

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(5) Inter symbol interference (ISI)

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(2) Slope overload error

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b). Derive the mathematical expression for FM with neat sketch.

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X525Y13A008X525Y13A008X525Y13A008X525Y13A008
Draw the resulting waveform if the sequence is transmitted using
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******************************************
(iv) skip distance

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4. Split phase Manchester 5. M-ary where M=4 (Polar quaternary)

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(ii) critical Frequency

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Paper / Subject Code: 51424 / Principle of Communication

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a). Consider that bit sequence given below is to be transmitted Bit sequence =10110011.

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b). Draw the block diagram of BSK generation & detection explain the working giving

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(3) quantization process

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