Reliable LDA-spectra by resampling and ARMA-modeling

Laser-Doppler Anemometry (LDA) is used to measure the velocity of gases and liquids with observations irregularly spaced in time. Equidistant resampling turns out to be better than slotting techniques. After resampling, two ways of spectral estimation are compared. The first estimate is a windowed periodogram and the second is the spectrum of a time series model. That is an estimated autoregressive moving average (ARMA) process whose orders are automatically selected from the data with an objective statistical criterion. Typically, the ARMA spectrum is better than the best windowed periodogram.