## Principles of Analog & Digital Comm. - December 2016

### MU Information Technology (Semester 3)

Total marks: --

Total time: --
INSTRUCTIONS

(1) Assume appropriate data and state your reasons

(2) Marks are given to the right of every question

(3) Draw neat diagrams wherever necessary

### Solve any four questionQ.1(a,b,c,d,e)

**1(a)**An amplifier has a bandwidth of 4 MHz with 10 K as the input resistor. Calculate the rms noise voltage at the input to this amplifier, if th e room temperature is 25°C. 5 marks

**1(b)** Explain Eye pattern with neat diagram.
5 marks

**1(c)** Explain Quantization.
5 marks

**1(d)** State and prove the differentiation in time domain property of the Fourier Transform.
5 marks

**1(e)** What is diagonal clipping and explain how it can be avoided.
5 marks

**2(a)** The AM Transmitter develops an unmodulated power o/p 400 Watts across a 50 ohms resistive load. The carrier is modulated by a sinusoidal signal with a modulation index of 0.8 Assuming fm= 5KHz and fc= 1MHz.

i) Obtain the value of carrier amplitude Vc and hence write the expression for AM signal.

ii) Find the total sideband power.

iii) Draw the AM wave for the given modulation index.
5 marks

**2(b)** Explain any one generation method SSBSC AM.
5 marks

**3(a)** Derive the mathematical expression for FM.
5 marks

**3(b)** Explain Foster seeley descriminator with neat block diagram and compare the performance with Ration detector.
5 marks

**4(a)** State and prove Sampling theorem ans explain the aliasing error.
5 marks

**4(b)** Explain generation and demodulation of PPM.
5 marks

**5(a)** Explain the Delta modulator Transmitter and receiver with neat block diagrams.
5 marks

**5(b)** The binary data 11010101 is transmitted over a baseband channel. Draw the waveform for transmitted data using the following data formats.

i) Unipolar NRZ ii) Unipolar RZ iii) Bipolar RZ iv) Split phase Manchester v) Polar quaternary NRZ.
5 marks

### Write a short note any four Q6..(a,b,c,d,e)

**6(a)**Explain wired communication channel. 5 marks

**6(b)** Derive Friss formula
5 marks

**6(c)** Explain QPSK.
5 marks

**6(d)** Compare TDM and FDM
5 marks

**6(e)** Explain BFSK Transmitter.
5 marks