Question

The frequency deviation in a FM transmission is $18.75KHz$. If it broadcasts in $88-108MHz$ band, then the percent modulation is

• A. $10\%$
• B. $25\%$
• C. $50\%$
• D. $75\%$

Answer 1

Answer: (B)

$25\%$

For given transmission band $88-108MHz$
${\left(\Delta f\right)}_{max}=75kHz$
Given, ${\left(\Delta f\right)}_{actual}=18.75kHz$
$\therefore \%modulationm=\frac{{\left(\Delta f\right)}_{actual}}{{\left(\Delta f\right)}_{max}}\times 100=\frac{18.75}{75}=25\%$