# Relationships between $f(t)$ signal and $f(t) \times \sin(\omega t)$ signal

Let's assume that there is a signal $f(t)$, $0\le t \le T$. Then, is there any special meaning of the signal $g(t) =f(t) \times \sin(\omega t)$? Like AM transmission. What is shown/heard when we play $g(t)$ in an audio player? Is there/what are meaningful differences between $g(t)$ and $f(t)$?

• well, what kinda textbook or internet resource might you look for to understand AM transmission? – robert bristow-johnson Apr 26 '18 at 11:37
• Look up the "modulation" or "frequency shifting" property of the Fourier transform. As to how $g(t)$ sounds, I'd suggest to go ahead and try for yourself: using Matlab or any similar language, read an audio WAV file, multiply by a sinusoid, and play the result. – MBaz Apr 26 '18 at 13:16