Question

$100MHz$ FM carrier wave frequency is modulated by $10kHz$ sinusoidal modulating signal. If the maximum frequency deviation is $50kHz$, what is the value of modulation index?

• A. 5
• B. 10
• C. 20
• D. 2.5

Answer 1

The correct option is A 5

The modulation index in frequency modulation is the ratio of frequency deviation ($\Delta f$) to the frequency of the modulating signal ($f_m$).
i.e Modulation index $=\frac{\Delta f}{f_m}=\frac{50kHz}{10kHz}=5$