An approach to passive impulsive source range estimation in shallow water is proposed. The approach is based on warping transformation of the energy density function of the received signal. Because of the influence of the sea bottom, it is diffcult to find a warping operator adapted to the dispersion characteristics of modes in shallow water. Even though the modes can be separated from each other by using the warping operator adapted to the ideal waveguide, it is impossible to obtain the analytic solutions of the characteristic frequencies, while the energy density function of the received signal is not affected by the sea bottom. Like the received signal and the autocorrelation function of the signal, the frequency spectrum of the warped energy density function of the received signal also owns invariable frequency features. These characteristic frequencies equal the difference in the cut-off frequency between two modes in ideal waveguide, which are easy to calculate with the knowledge of the depth and the average sound speed of the water. What is more, the warping operator transforms mode pairs in energy density function with the same mode number difference into one monotone, which means one characteristic frequency is not unique for one mode pair. In shallow water, the acoustic field is typically composed of a group of modes with close mode numbers. Therefore, the smaller the mode number difference, the more the mode pairs, and the higher the spectral peak of the corresponding monotone is. When the source range is unknown, the approximate relation formula between the extracted characteristic frequency in a supposed source range and the real characteristic frequency is derived, based on which a fast passive source range estimation method is proposed. The proposed method successfully avoids using the guide source and the calculation of replica field, which is necessary in existing passive range estimation algorithms. And applying warping operator to the energy density function of the received signal makes it easy to obtain the analytic solutions of the characteristic frequencies, which is impossible in previous researches. The method is successfully applied to the Yellow Sea impulsive signal data collected by a single hydrophone in November 2011. The mean relative error of range estimation is less than 8%.%针对浅海波导中脉冲声源被动测距问题，提出了一种利用接收信号的能量密度函数进行warping变换的声源被动测距方法。对于浅海波导，接收信号的能量密度函数中不同号简正波相干部分，经warping变换后输出结果的频谱中包含与声源和接收器位置无关的不变性频率特征。这些特征频率在数值上等于理想波导中相干的两号简正波的截止频率差，与海底参数无关，因此仅需已知海水中的平均声速和海水深度便可计算出特征频率值。当声源距离未知时，利用特征频率的提取值与真实特征频率之间的关系可以实现快速测距，极大地提高了计算速度。为了验证方法的有效性，对2011年11月黄海海域水声实验的接收脉冲数据进行了处理，测距结果与实测距离符合良好，平均测距误差在8%以内。
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