Application of complex cepstrum filter in TDR waveform analysis

Accurate measurement of traveling time on TDR probe is important to apparent permittivity test in TDR measurement system. TDR measurement waveform is composed of first main reflection and multi-reflections. Complex cepstrum filter can separate the first main reflection from the echo like multi-reflection waveforms of the original data. In this paper, multi-reflection model of TDR measurement system is illustrated and the TDR waveform is analyzed in complex cepstrum domain. After filtered in cepstrum domain, the first main reflection of TDR measurement is separated from original waveform. The simulated waveforms is calculated by TDR main reflection and multi-reflection model. The simulated waveform is close to the original waveform measured by TDR device. The experiment results of tap water, alcohol and soil sample show that filtering in cepstrum domain can achieve accurate apparent permittivity.