A method and system for determining a physical property as a function of position. A data series including data point from one or more channels is obtained by frequency modulation continuous wave. A number of data points correspond to Nda different values of frequency of modulation. One or more processing steps are performed including at least part of said primary data series to obtain at least one secondary data series comprising N (N>Nda) data points from the values of frequency of modulation. The secondary data series from frequency domain is transformed to obtain at least one back scattering curve in space domain, and optionally the back scattering curve(s) to one or more physical properties as a function of position.