Which statement is true about indirect FM modulator?

William Johnson

New member
Which statement is true about indirect FM modulator?
A. it integrates the modulating signal
B. it differentiates the modulating signal
C. varies the frequency of carrier oscillator
D. varies the phase of carrier oscillator
 
Answer: D
Explanation: Frequency modulated system can be produced either by direct ways or indirect ways. Armstrong method comes under indirect method. Direct FM modulator is generally used to vary the frequency of carrier oscillator, thus being known as frequency discrimination method, while indirect FM modulator varies the phase of carrier oscillator, thus being called phase discrimination method.
 
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