I have several files from Fourier analysis as a result of data processed in Statsoft Statistica. I need to determine the uncertainty with which a given frequency has been estimated and what is the time period,
Confidence levels give you a certainty indication that the samples you are measuring come from the same "generating mechanism". Confidence levels depend on the number of samples available and their standard deviation. I would advise you to look at the following paper:
Multiresolution semantic activity characterisation and abnormality discovery in videos