The OFDR system provides information on the local characteristic of fiber network with high resolution and moderate range. It measures the backscatter signal during the entire measurement span as a function of frequency in a complex fashion, and then Fourier transformation is applied to the result in order to retrieve time domain response .

Signal at different time delay corresponds to events happened at different location along the fiber. The essential benefits of OFDR technology are the quasi continuous wave mode employed by the laser and the narrow-band detection of the optical back scatter signal, whereby a significantly higher signal to noise ratio is achieved than with conventional pulse technology (OTDR).