# EC6651 Communication Engineering Question Bank

Anna University, Chennai
Department of Electronics and Communication Engineering
Subject Code: EC6651
Subject Name: Communication Engineering
Question Bank
VEC Edition

UNIT – I
ANALOG COMMUNICATION
PART -A
1. Define modulation index of FM. (BT-1)
2. A carrier signal with power of 40 watts is amplitude modulated by a sinusoidal signal. Calculate
the power of the modulated signal if the modulation is 0.7. (BT-3)
3. Describe the need for modulation. (BT-2)
4. Explain about image frequency? How it is rejected? (BT-4)
5. Formulate the relationship between phase and frequency modulation. (BT -6)
6. Label the frequency spectrum of AM wave with a neat sketch. (BT-1)
7. Give the characteristics features of spectrum of AM wave. (BT-2)
8. Differentiate amplitude modulation and frequency modulation. (BT-2)
9. List the disadvantages of single side band transmission. (BT-1)
10. Define quantization error. (BT-1)
11. Summarize the advantage of FM over AM. (BT-2)
12. A transmitter radiates 9 KW with the carrier unmodulated and 10.125 KW when carrier is
sinusoidally modulated. Calculate the modulation index. (BT-3)
14. Explain about Energy and power signals. (BT-4)
15. An AM transmitter is modulated by three source of audio with m1=0.5,m2=0.7,m3=0.4.The
unmodulated carrier power is 50 kw. Calculate the modulated power output. (BT-3)
16. Define modulation index of FM. (BT-1)
17. Compare NBFM and WBFM. (BT-5)

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