I'm trying to estimate the power spectrum and time delay for random signals. the signals were taken from two sensors, 10 cm apart. My aim is to estimate the PSD first then estimate the time delay in order to obtain the structure velocity. I've tried the traditional way by using matlab built-in functions like fft, xcorr. however the results were not as I expected. is there a better way to analyse the attached signals please? Does it need filtering?
The signals represent the void fraction data that was measured for 60s with sampling frequency of 1000hz. the time delay expected to be in ms( around 500ms).
1.Cross Correlation 2.AUTO_CORRELATION
4.Cross Correlation after subtracting the average 60000 points
HERE'S THE DATA