A signal of frequency $f_m=5\text{ kHz}$ is amplitude modulated on a carrier wave of frequency $f_c=2\text{ MHz}$. Calculate the sideband frequencies $f_{USB}$ and $f_{LSB}$.

Solution

1. Given the carrier frequency $$\begin{array}{rl}{f}_c& =2\text{ MHz}\\ & =2000\text{ kHz}\end{array}$$ and the modulating frequency $f_m=5\text{ kHz}$.
2. The upper sideband frequency is calculated as $$\begin{array}{rl}{f}_{USB}& =f_c+f_m\\ & =2000\text{ kHz}+5\text{ kHz}\\ & =2005\text{ kHz}\\ & =2.005\text{ MHz}\end{array}$$.
3. The lower sideband frequency is calculated as $$\begin{array}{rl}{f}_{LSB}& =f_c-f_m\\ & =2000\text{ kHz}-5\text{ kHz}\\ & =1995\text{ kHz}\\ & =1.995\text{ MHz}\end{array}$$.
4. Hence the answer is (A).