Question

In an angle modulated signal, the modulating frequency is increased from 20 kHz to 40 kHz.If the signal is frequency modulated, then the modulated signal bandwidth is

• A. Halved
• B. Decreased by 40 kHz
• C. Doubled
• D. Increased by 40 kHz

Answer 1

The correct option is D Increased by 40 kHz

$BW=2(\Delta f+f_m)=2\Delta f+2f_m(BW{)}_{new}=2\Delta f+2f_{new}=2\Delta f+2(f_m+20)=2\Delta f+2f_m+40kHz(BW{)}_{new}=\left(BW\right)+40kHz$