STUPIDSID
1 (a)
Describe mean, correlation and covariance functions with respect to stationary random process.
6 M
1 (b)
State and discuss central limit theorem.
8 M
1 (c)
Let X be a continuous random variable having a uniform probability distribution defined in the range 2≤x≤4. Let y=3X+2. Find the means mx and my.
6 M
2 (a)
Explain the need for modulation.
6 M
2 (b)
Describe the generation of AM wave using square law modulator with mathematical analysis.
8 M
2 (c)
The antenna current of an AM transmitter is 8 amps, when only the carrier is sent. But it increase to 8.93 amps, when the carrier is modulated by a single sine wave. Find the percentage modulation. Determine the antenna, when the percentage modulation changes to 0.8.
6 M
3 (a)
What is Hilbert transformation? Derive the expression for impulse response of the Hilbert transformer.
7 M
3 (b)
Write the canonical representation of band pass signal and derive the expression for time function of SSBSC waveform.
8 M
3 (c)
Calculate the percentage power saving when the carrier and one of the sidebands are suppressed in an AM wave modulated to a depth of (i) 100% and (ii) 50%.
5 M
4 (a)
With neat block diagram, explain the generation of VSB wave by phase discrimination method.
7 M
4 (b)
Discuss envelope detection of VSB plus carrier.
6 M
4 (c)
Explain the transmission of a number of independent signals over a single communication channel by modulating different carrier signals.
7 M
5 (a)
Explain the generation of wide band frequency modulated wave by Armstrong method.
7 M
5 (b)
A 100 MHz carrier wave has a peak voltage of 5 volts. The carrier is frequency modulated by a sinusoidal modulating waveform of frequency 2 KHz such that the frequency deviation is 75 KHz. The modulated wave form passes through zero and is increasing at time t-0. Write the expression for frequency modulated signal.
5 M
5 (c)
Show that the spectrum of FM contains infinite number of side bands.
8 M
6 (a)
With neat schematic and frequency response, explain the operation of balanced discriminator for demodulation of FM wave.
7 M
6 (b)
With relevant mathematical analysis, explain reconstruction of message signal form FM wave by PLL.
8 M
6 (c)
Discuss non linear effects in FM systems.
5 M
7 (a)
What are the types of noise, which affect communication system? Explain thermal noise in detail.
7 M
7 (b)
An amplifier operating over the frequency range of 450 KHz to 460 KHz is having a input resistance of 75 KΩ. If the temperature is 15°C, find :
i) The RMS noise voltage at the input to the amplifier.
ii) The amplifier noise power.
iii) Power spectral density.
i) The RMS noise voltage at the input to the amplifier.
ii) The amplifier noise power.
iii) Power spectral density.
6 M
7 (c)
Discuss the noise factor of amplifier in cascade and obtain the Friss formula.
7 M
8 (a)
Show that the figure of Merit of SSBSC system is unity.
8 M
8 (b)
Discuss threshold effect in FM receiving system.
4 M
8 (c)
Explain in detail the pre-emphasis and de-emphasis in frequency modulation.
8 M
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