Uncertainties in the estimation of low frequency noise level extracted from noise spectral density measurements

It is well known that measurement uncertainty of noise spectral density is related to the time length of observation. With FFT spectrum analyzers, the measurement error can be reduced by averaging Navg measurements. Standard error is then reduced by the square root of Navg. This paper deals with the error introduced when one wants to extract from the noise spectral density measurement the 1/f level, white noise level and lorentzian parameters. In that purpose, different estimation techniques from different groups are compared and discussed.