When you say "Integer and non-integer frequency components", are you interested in integer frequency or integer gain and phase? I'm going to assume the former.
Do you have an understanding of Signals and their analysis? Do you know the relationship between the following concepts, especially as they relate to an FFT?
- Sampling Frequency (usually in Hz)
- Sampling Period (time, in seconds, over which samples are taken)
- Number of Samples
- Highest Frequency in Spectrum
- Lowest Frequency in Spectrum
- Number of Frequencies in Spectrum
- Frequency spacing (difference) between Spectrum points
Note that there are really only two independent variables in the above list of 7 quantities (if this isn't obvious to you, do some reading).
In a proper spectrum, all spectral frequencies are an integer multiple of a "fundamental". If the fundamental (determined by your sampling parameters) can be expressed as an integer (e.g. "10 Hz"), then all the spectral frequencies will be integers. [Yes, yes, the computations are carried out by Floats, not Integers, and are based on hardware that don't give exact integer timing, but I'm assuming that we can get "sufficiently close" to ignore the tiny errors ...].
Bob Schor
