Question

$\text{A frequency modulated signal with a carrier frequency of}{}^{\prime \prime }{f}_c^{\prime \prime }\text{is given by,}\text{The maximum phase deviation of the signal s(t) is}s\left(t\right)=10cos[2\pi f_{c}t+4sin(1500\pi t)+3cos(1500\pi t\left)\right]$

• A. $\text{3 radians}$
• B. $\text{5 radians}$
• C. $\text{4 radians}$
• D. $\text{7 radians}$

Answer 1

The correct option is B $\text{5 radians}$

$\text{The phase of the given modulated signal is,}\varphi \left(t\right)=4sin\left(1500\pi t\right)+3cos\left(1500\pi t\right)rad=\sqrt{(4{)}^2+(3{)}^2}\left[cos\right(1500\pi t-\alpha ]rad=5cos(1500\pi t-\alpha )rad\text{where,}\alpha =ta{n}^{-1}\left(\frac{4}{3}\right)\text{Maximum phase deviation of the signal s(t) is,}\Delta {\varphi }_{max}=|\varphi (t){|}_{max}=5radians$