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Electronics and Communication Engineering - Communication Systems - Discussion

Discussion Forum : Communication Systems - Section 1 (Q.No. 7)
Communication Systems
7.
In FM signal with a modulation index mf is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of
mf
3mf
mf/3
mf/9
Answer: Option
Explanation:

Frequency multiplier increase the deviation,

.

Discussion:
8 comments Page 1 of 1.
Ammar said:   6 years ago
x(t) = A sin( 2pi (fc + mf cos (wm t))t + π).
Wc = carrier frequency (rad/sec),
Wm = baseband signal frequency,
mf = delta f/fm.

Delta f = baseband signal spread or amplitude.

When passed through a frequency multiplier. The frequency part of the sign will be multiplied by 3 i.e. 3fc + 3mf. Therefore it be 3mf.
Ravindra said:   8 years ago
Actually 'B' is the correct answer, because Frequency multiplayer will change carrier frequency only. It will not alter the message signal frequency. So only modulation index will be changed according to multiplication factor.
Prabhat kumar said:   10 years ago
A frequency multiplier has the property that the frequency of the output signal has an integer.

Multiple of the input frequency Fm will become 3fm and modulating index will be mf/3.

Option (C) should be correct answer.
Santosh said:   1 decade ago
When given to a frequency tripler does frequency deviation get effected or the frequency itself?
Swetha bindhu said:   9 years ago
Yes, C should be the correct answer.
Jayanta said:   9 years ago
The answer A should be correct.
Rashmi said:   9 years ago
How? Please tell me clearly.
Shivam said:   8 years ago
Where can we use it?
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