If I have a 100 Hz periodic analog signal and let us say it is band limited to 1kHz and I sample it at 3 kHz. If I want to see its frequency spectrum then how to differentiate between the signal frequency 100 Hz from the sampling frequency 3 kHz in the spectrum?
What I understand is that frequency spectrum shows the frequency components at even or odd or mix multiples of a fundamental frequency. But what I don't understand is that whether the frequency is the periodic signal frequency or the sampling frequency?
If it is the harmonics of the fundamental signal frequency then how to find out the sampling frequency from looking at the spectrum?