I'm having a bit of trouble with the PSD on my particle tracking program. If I ask it to give me the PSD of a generated sine wave for example, its fine. However, when I exchange the input signal with, say, the x-coordinates of a tracked particle, I get a constant value of -infinity! I am using the centroid function to give me the x-coordinate of the particle. Any ideas what i'm doing wrong? I've also tried converting the coordinate to dynamic data.