GATE EC 2017 Set 2 — Question 51
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Communications → Analog Communications → Angle Modulation (FM & PM)
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Question
A modulating signal given by is fed to a phase modulator with phase deviation constant . If the carrier frequency is , the instantaneous frequency (in kHz) at is ___________
Correct answer
69.9 to 70.1
Solution
The output of a phase modulator is given by:The instantaneous phase is .
The instantaneous frequency is defined as:Given . Let .
Then .Calculating :At :
The instantaneous frequency is defined as:Given . Let .
Then .Calculating :At :
1..
2., so .
3., so .
4..
Now, substitute into the instantaneous frequency formula:The instantaneous frequency is .Continue learning with Success Tracker
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