I was browsing another topic, and I suddenly remembered that I've never quite figured out what units matlab's fft returns. I've used the fft before and found where I had signal noise by taking the power density of the fourier coefficients, which is all I really wanted to use the fft for in the first place. Still, I'm curious what would need to be done to get a useful measurement like volts/sqrt(Hz), or volts^2/Hz. The units after the FFT should still be in volts, so would all I need to do is divide by frequency, and take the complex conjugate or complex conjugate root? Anyone done this before, if so mind posting your code for me to look at? My initial search on the internet, even through the mathworks site, still reveals nothing very concrete.