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Module 1: Analog Modulation

20252m

In FM, the parameter varied in proportion to the message signal is
(i) Amplitude
(ii) Frequency
(iii) Phase only
(iv) Amplitude and phase

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Answer

Correct Option: (ii) Frequency

Explanation

Frequency Modulation: Instantaneous frequency fi(t)=fc+kfm(t)f_i(t)=f_c+k_f m(t) varied proportional to message m(t)m(t). Amplitude AcA_c constant, phase θ(t)=2π∫fidt\theta(t)=2\pi\int f_i dt. PM varies phase, FM varies frequency (integral of PM).

Final Answer

Frequency varied → Option (ii).

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