# Mumbai University Sample Paper Principles of Communication Engineering

Table of Contents

**Mumbai University Sample Papers **

**IT 4th Sem Principles of Communication Engineering**

**(1) Question no. 1 is compulsory**

**(2) Attempt any four out of remaining six questions.**

**(3) Assume suitable data if required.**

**(4) Figures to the right indicate full marks.**

1. (a) Calculate total power and power in each sideband for standard AM transmission 20

that is sinusoidally modulated to depth of 80% if the unmodulated carrier power is

50kW.

(b) The carrierfrequencyof FMbroadcasttransmitteris 100MHzand maximumfrequency

deviation is 75 KHz. If the highest audio frequency modulating the carrier is

15 KHz, what is the approximate bandwidth of the signal.

(c) Compare narrow band and wideband FM.

(d) Compare PCM and OM.

2. (a)

(b)

Define Amplitude Modulation and derive the equation for Amplitude Modulated wave.

A certain transmitter radiates 9 kW with the carrier unmodulated and 10.125 kW

when the carrier is sinusoidally modulated.

Calculate the modulation index.

If another sinewave, corresponding to 40 percent modulation, is transmitted

simultaneously, determine the total radiated power.

.

3. (a) With the help of neat circuit diagram and phasor diagram explain the working of

Foster – Seeley discriminator.

(b) Find the carrier and modulating frequencies the modulation index and 10

the maximum deviation of the FM wave represented by the voltage equation

e = 12 Sin ( 6 x 108t + 5 Sin 1250 t). What power will this FM wave dissipate in

a 10 Q resistor?

4. (a) What is a ‘Balanced Modulator’ ? Sketch a Balanced Modulator circuit and explain

its working.

(b) Find the Fourier Transform of the following:

(i) 8(t)

(ii) Coswot.

5. (a) Draw the block diagram of superheterodyne receive and describe the function of

each block.

(b) Explain the following as applicable to Radio Receivers :-

(i) Fidelity

(ii) Image Frequency and its rejection

(iii) Tracking

(iv) Selectivity.

6. (a) Compare

(i) FOM and TOM

(ii) ASK and FSK.

(b) Explain Satellite Communication Systems. List the applications in Satellite 10

Communication.

7. (a) How is adaptive Delta Modulation an improvement over linear Delta Modulation. 10

Draw block diagram of adaptive Delta Modulation and explain its working.

(b) Define Signal to Noise Ratio. Explain the effect of cascade connection on Signal 10

to Noise Ratio. Calculate the overall signal to Noise Ratio at the output in decibels

for 3 identical links, given the Signal to Noise Ratio for anyone link is 40 dB.