Rajasthan Technical University 2009-5th Sem B.E Electrical Engineering : (B.Tech- ) Principal of communication system - Question Paper
Rajasthan tech. University(RTU)
B.Tech V sem. Main exam
2009
Principal of communication system
KoiiNo.
Total No. of Questions : 5] |Total No. of Pages : 2
B.Tech. Vth Semester Main Examination - 2009 Electrical Engineering Principle of Communication systems (5EE6.2) 5E3129
Time : 3 Hours- Maximum Marks : 80
Min. Passing Marks: 24
Attempt five questions in all selecting One question from each unit. Schematic diagrams must be shown wherever necessary. Any data you feel missing may suitably be assumed and'Slated clearly. Units of quantities used/calculated must be stated clearly. All questions carry equal marks.
1. (<>) Explain the following -
(i) Noise bandwidth
(ii) Resistor Noise. , (4+4)
(b Evaluate the expression for equivalent noise temperature in two port Cascade network. (8)
OR
(a) An amplifier operating on a frequency range from 18 to 20 MHz has a 10AX2 input resistance. Find the noise voltage at the input to this amplifier if the ambient temperature is 21' C. (8)
(b) Explain the following -
(i) Noise figure
(ii) Noise temperature (4+4)
2. (a) Ah SSB transmission contains 10KW power. This transmission is to be
replaced by a standard amplitude modulated signal with the same power content. Determine the power content of the carrier and each of the sidebands when the percentage modulation is 80% (S)
(b) What are the generating methods for SSB -SC signal ? (8) 1
5E3129.150(1
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//Ta) Determine the power content of each of the sidebands and of the can AM signal that has a percentage modulation of 85% and contains 11 total power.
(b) Explain the working of envelope detector and square law demodula? S
A single - tone FM is represented by the voltage equation as
v(() =12 Cos (6AriOf 3Sm 1250f) . V '
V
Determine the following.
(i) Carrier frequency
(ii) modulating frequency
fiii) modulation index
(iv) maximum frequency deviation.
(fc) Explain the various methods of FM generation.
(a) A carrier is frequency modulated by a sinusoidal modulating signal of *r 2 KHz, it results in.a frequency deviation A f of 5 KHz . Find the bai occupied by the FM wave form. The amplitude of the modulating sin increased by a factor of 3 and its frequency lowered by 1 KHz. Find bandwidth.
(b) Explain the working of pre-emphasis and de-emphasis circuits. Wha: advantages of these circuits?
4. (a) Calculate the output signal to noise ratio of square Law demodulator': (b) Calculate the signal to noise ratio in FM demodulators.
(a) Calculate the output signal to noise ratio of envelope detector.
(b) Explain the working of super-heterodyne receivers what are the adv ai of this?
5. (a) State and prev e sampling theorem in time domain.
(b) Explain the generation and demodulation of PW'M .signal.
fa) Explain the generation and demodulationPP.\ 1 signal.
(b> Compare the advantages and disadvantages of PAM. PW'M and PP\
5E3129 (2)
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| Earning: Approval pending. |
