B.TECH - Semester 4 analog communication Question Paper 2019 (jun)
Practice authentic previous year university questions for better exam preparation.
Sample Questions
- An audio frequency signal $10 \sin 2 \pi^{\star} 500 t$ is used to amplitude modulate a carrier of $50 \sin 2 \pi * 10^{5} t$. Assume modulation index $=0.2$. Find (a) Sideband frequencies. (b) Amplitude of each sideband frequencies.
- The total antenna current of an $A M$ transmitter is $5 A$. If the modulation index is 0.6 , calculate the antenna current when only the carrier is sent.
- Draw time domain and frequency domain representations of a DSBSC wave.
- Explain the significance of image frequency.
- Calculate the carrier frequency and modulation index for an FM signal which reaches a maximum frequency of 99.047 MHz and a minimum frequency of 99.023 MHz . The frequency of the modulating signal is 7 KHz and frequency deviation is 12 KHz .
- Briefly explain generation of narrowband PM using DSBSC modulator.
- Explain the working local loop is telephone system.
- Discuss briefly the differences between thermal noise and shot noise. P.T.O.
- Calculate the noise voltage at the input of a radio receiver's RF amplifier, using a device that has $100 \Omega$ equivalent noise resistance and a $200 \Omega$ input resistor. The bandwidth of the amplifier is 1 MHz and temperature is $25^{\circ} \m...
- What is pre-emphasis? Why is it used? Answer any two questions from each Module. Each question carries 10 marks.
- (a) Explain the operation of a ring modulator circuit which generates the DSBSC wave.
- (b) Explain square law detector to demodulate an AM signal.
- A message signal $m(t)$ with spectrum shown in Fig 1 is applied to a product modulator with a carrier wave $A_{c} \cos \left(2 \pi f_{c} t\right)$ producing the DSBSC modulated wave $\mathrm{s}(\mathrm{t})$. This modulated wave is next applied to a c...
- A message signal $m(t)$ with spectrum shown in Fig 1 is applied to a product modulator with a carrier wave $A_{c} \cos \left(2 \pi f_{c} t\right)$ producing the DSBSC modulated wave $\mathrm{s}(\mathrm{t})$. This modulated wave is next applied to a c...
- A message signal $m(t)$ with spectrum shown in Fig 1 is applied to a product modulator with a carrier wave $A_{c} \cos \left(2 \pi f_{c} t\right)$ producing the DSBSC modulated wave $\mathrm{s}(\mathrm{t})$. This modulated wave is next applied to a c...
- (a) Explain phase shift method of SSB generation with lower side band.
- (b) Explain with a block diagram, super heterodyne receiver.
- Explain Armstrong method of generating FM wave. Mention the advantages and disadvantages of the method.
- Derive an expression for the spectrum of FM wave with sinusoidal modulation.
- With a block diagram approach, explain the operation of FM stereo multiplexing with multiplexer in transmitter of FM stereo and demultiplexer in receiver of FM stereo.
- Derive an expression for equivalent noise temperature of overall circuit having number of amplifiers connected in cascade connection.
- (a) Three amplifiers have following characteristics Amplifier 1: $\quad \mathrm{F}_{1}=8 \mathrm{~dB} \mathrm{G}_{1}=42 \mathrm{~dB}$ Amplifier 2: $\quad \mathrm{F}_{2}=9 \mathrm{~dB} \mathrm{G}_{2}=38 \mathrm{~dB}$ Amplifier 3: $\quad \mathrm{F}_{3...
- (b) What is the effective bandwidth of a 100 pF capaciter connected in parallel with $10 \mathrm{~K} \Omega$ resistor?
- Discuss the working of public telephone network with block diagram. $$ \text { ( } 6 \times 10=60 \text { Marks) } $$