*Fourier Series*to represent arbitrary periodic signals and

*Fourier Transforms*to represent non-periodic signals. Computer methods, based on these analysis approaches, are commonly used to determine the frequency components present in measured signals. A detailed discussion of these approaches is currently beyond our capabilities; at the moment, we simply ask that you believe that nearly any time domain signal can be represented to some extent in the frequency domain. For the immediate future, we will assume that the frequency domain representation of any signals of interest is directly available.