What is the modulation index in a frequency modulated signal with a modulating frequency of 500 Hz and frequency deviation of 10 kHz?

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  1. 10
  2. 20
  3. 25
  4. 50

Answer (Detailed Solution Below)

Option 2 : 20
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Concept:

In FM (Frequency Modulation), the modulation index is defined as the ratio of frequency deviation to the modulating frequency.

Mathematically, this is defined as:

\(m_f=\frac{Δ f}{f_m}\)

mf = Modulation index

Δf = Frequency deviation

fm = Modulating frequency

Calculation:

Given Δf = 10 kHz

fm = 500 Hz

\(m_f=\frac{10~kHz}{500~Hz}=20\)

26 June 1

A wave has 3 parameters Amplitude, Phase, and Frequency. Thus there are 3 types of modulation techniques.

Amplitude Modulation: The amplitude of the carrier is varied according to the amplitude of the message signal.

Frequency Modulation: The frequency of the carrier is varied according to the amplitude of the message signal.

Phase Modulation: The Phase of the carrier is varied according to the amplitude of the message signal.

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