VRS&YRN COLLEGE OF ENGINEERING AND TECHNOLOGY: CHIRALA

UNIT I Assignment Questions

NAME OF THE SUBJECT: Analog communications NAME OF THE FACULTY: B.Umasankar

BRANCH: Electronics and communication engineering YEAR : II/IV B-tech II-Sem

1. With necessary expressions, waveforms and spectrums, explain AM for an arbitrary baseband signal m (t).

Ap r/May -10 regular, set-1

2. The output power of an AM transmitter is 1KW when sinusoidally modulated to a depth of 100℅.calculate

the power in each sideband when the modulation depth is reduced to 50℅

Ap r/May -10 regular, set-1

3. What are the main objectives and primary Resources of a communication system?

Ap r/May -10 regular, set-2

4. A broadcast AM Transmitter radiates 50 KW of carrier power what will be the radiated power at 85℅of

Modulation and what is the sideband power

Ap r/May -10 regular, set-2

5. Draw the one cycle of AM wave and calculate the modulation index of it in terms of Vmax and Vmin voltages

Ap r/May -08 regular, set-3&4, Aug/sep-08 supply, set-4

6. The RMS current of an AM Transmitter is 10A when un-modulated and 12A when sinusoidally modulated

calculate the modulation index. Ap r/May -08 regular, set-3&4, Aug/sep-08 supply, set-4

7. Explain the collector modulation method for generating AM wave with a neat circuit diagram and waveforms.

Aug/sep-08 supply, set-1, 2

8. An AM amplifier provides an output of 106W at 100℅ modulation. The internal loss is 20w

(i) Find the UN modulated carrier power (ii) What is the sideband power.

Aug/sep-08 supply, set-1,2

9. Describe the phasor representation of AM wave and also explain the trapezoidal method of finding

modulation index. Aug/sep-08 supply, set-2

10. An AM voltage is given by s (t) =50(1+0.2 Cos 100t+0.01cos3500t) cos106t.state all the frequency

components (in HZ) present in the voltage, and find the modulation index for each modulating voltage term.

Calculate the effective modulation index of s(t) Aug/sep-08 supply, set-3

11. A carrier of frequency 10MHz and peak value of 10v is amplitude modulated by a 5KHz sine wave of

amplitude 6v.determine the modulation index and draw the one sided spectrum of modulated wave.

Ap r/May -09 regular, set-2

12. Explain the operation of square law detector with circuit diagram and waveforms.

Ap r/May -09 regular, set-3

13. The UN modulated carrier power of an AM transmitter is 10KW.it can be modulated by sinusoidal modulating

voltage to a depth of 40℅ without overloading. If the maximum modulation index is reduced to 30℅, what is

the extent up to which the UN modulated carrier power can be increased to avoid overloading?

Ap r/May -09 regular, set-3

14. An AM wave is given by s (t) =25(1+0.7cos5000t-0.3cos10000t) sin5*106t.

(i)What is the amplitude and frequencies of the carrier and sidebands? (ii) Determine the band width

(iii)Draw the one sided spectrum Ap r/May -07 regular, set-4 15. (a)Write AM equation. Define modulation index and percentage modulation

(b)Define under and over modulation. Explain why over modulation is undesirable. Aug/sep-08 supply, set-2