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Narrowband FM is used in which of the following applications?

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RRB JE ECE 22 Apr 2025 Shift 1 CBT 2 Official Paper
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  1. Television transmission
  2. High-fidelity audio systems
  3. FM radio broadcasting
  4. Two-way mobile radio communication

Answer (Detailed Solution Below)

Option 4 : Two-way mobile radio communication
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Detailed Solution

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The correct answer is: 4) Two-way mobile radio communication

Explanation:
Narrowband FM (NBFM) is characterized by:

Small frequency deviation (typically ±5 kHz or less).

Limited bandwidth (just wide enough for voice communication).

Primary Applications:

  • Two-way mobile radios (e.g., police, ambulance, taxi communications).
  • Aviation and marine VHF radios.
  • Amateur radio (ham) transmissions.
     

Why Not the Other Options?

  • Television transmission → Uses wideband FM for audio (higher fidelity) or AM for video.
  • High-fidelity audio systems → Requires wideband FM (e.g., ±75 kHz deviation for FM radio).
  • FM radio broadcasting → Uses wideband FM (88–108 MHz band with large deviation).
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