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Question 20308
JEE Physics · Hard

Principles of Communication: Communication System MCQ

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Communication SystemHardQuestion 20308

Question

In a communication receiver, the noise figure F is defined as:
  1. A
    Output SNR / Input SNR
  2. B
    Input SNR / Output SNR
    Correct
  3. C
    Bandwidth × Noise power
  4. D
    Gain × Noise temperature

Correct answer

Input SNR / Output SNR

Explanation

Noise Figure F = SNRin/SNRout (linear), or NF = 10 log₁₀(F) dB. F ≥ 1 always (a real device always adds noise). An ideal noiseless amplifier has F = 1 (0 dB). LNA (Low Noise Amplifier) at the front-end of a receiver should have NF < 1 dB to preserve system sensitivity.

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