Communication Systems – Multiple Choice Questions (MCQs)

1. 37. The Intermediate Frequency (IF) in a superheterodyne receiver is chosen for:

   • A. High gain and good selectivity
   • B. Low noise
   • C. High power handling
   • D. Ease of modulation

2. 38. Automatic Gain Control (AGC) in a receiver is used to:

   • A. Control frequency
   • B. Maintain constant output level
   • C. Reduce noise
   • D. Increase bandwidth

3. 39. A balanced modulator is used to generate:

   • A. AM signal with carrier
   • B. DSB-SC signal
   • C. SSB-SC signal
   • D. FM signal

4. 40. Vestigial Sideband (VSB) modulation is commonly used in:

   • A. Radio broadcasting
   • B. Television broadcasting
   • C. Satellite communication
   • D. Mobile communication

5. 41. The image frequency in a superheterodyne receiver is suppressed by:

   • A. RF amplifier
   • B. Mixer
   • C. IF amplifier
   • D. Local oscillator

6. 42. The noise figure of a receiver indicates its:

   • A. Power output
   • B. Sensitivity to noise
   • C. Bandwidth
   • D. Selectivity

7. 43. What is the minimum bandwidth required for an AM signal with a message bandwidth of B Hz?

   • A. B
   • B. 2B
   • C. B/2
   • D. 4B

8. 44. The maximum frequency deviation in FM is denoted by:

   • A. fm
   • B. Δf
   • C. β
   • D. kf

9. 45. The modulation index of an FM signal is also known as:

   • A. Frequency deviation
   • B. Phase deviation
   • C. Deviation ratio
   • D. Bandwidth

10. 46. Sampling of an analog signal converts it into a sequence of:

    • A. Pulses with varying amplitude
    • B. Pulses with varying frequency
    • C. Pulses with varying phase
    • D. Binary digits

11. 47. The process of converting a continuous-time signal into a discrete-time signal is called:

    • A. Quantization
    • B. Encoding
    • C. Sampling
    • D. Modulation

12. 48. In PCM

    • A. the number of bits per sample determines the:
    • B. Sampling rate
    • C. Quantization levels
    • D. Bandwidth