communication-systems Question 27
Question: Q. 5. In the given diagram $C(t)$ stands for the carrier wave and $m(t)$ for the signal to be transmitted. What name do we give to the wave labelled as $\mathrm{C}_{m}(t)$ in the diagram ?
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Solution:
Ans. $C_{m}(t)$ is the frequency modulated wave.
[CBSE Marking Scheme, 2014]
. 6. The carrier wave is given by
$$ C(t)=2 \sin (8 \pi t) \text { volt. } $$
The modulating signal is a square wave as shown. Find modulation index.
[Delhi I, II, III 2014]
Ans. Modulation Index $=\frac{a_{2}}{a_{1}}=1 / 2=0.5 \quad 1 / 2+1 / 2$ [CBSE Marking Scheme, 2014]
Detailed Answer :
From the given equation of carrier wave amplitude of carrier wave, $A_{c}=2$ volts
From the graph amplitude of signal wave,
$$ A_{m}=1 \text { volts } $$
Hence modulation index,
$$ \mu=\frac{A_{m}}{A_{c}}=\frac{1}{2}=0.5 $$
