Abstract: An approach for long-range passive impulsive source ranging with a single receiver in shallow water is derived,which utilizes the frequency spectrum of the warped signal autocorrelation function via warping transform.In an ideal waveguide,the frequency spectrum of the warped signal owns invariable frequency features i.e.modal cut-off frequencies.There also exist similar invariable frequency features for the warped signal autocorrelation function due to modal interference.The approximate relation formula between the characteristic frequency at an unknown source range and the intrinsic frequency extracted by the time warping transform is derived.These rules can be generalized to an actual shallow water waveguide and applied to passive source ranging.Employing an acoustic model to offer the invariable frequency spectrum features,the impulsive signal data collected by a single hydrophone in the North Yellow Sea in December 2011 are analyzed to verify the proposed source ranging approach.The estimated ranges are in good agreement with the measured,and the mean relative error of range estimation is less than 10%.