LAUSR

Abstract Spectral induced polarization (SIP) measurement requires synchronous current acquisition and real-timetransmission devices or precise phase-measuring apparatus. To carry out SIP investigations in the absence of these auxiliary devices, a new SIP measurement has been developed in this research. The new method uses high-accuracy phase-calculation technology based on all-phase spectrum analysis (APSA) to obtain the initial phase of the emission current and uses time information recorded in the file header of the voltage data file and the ‘Frequency-Time Table’ of the emission current to calculate the current phase information at any given moment. The phase-calculation method for the voltage data was the same as that used for the current initial phase. Subsequently, the phase of the complex resistivity was obtained by subtracting the current phase from the voltage phase, and the amplitude was obtained by normalization. Simulation tests showed that the algorithm was superior for absolute phase measurement compared with other spectrum analysis methods and confirmed that the accuracy of the new method was equal to that of the measurement that collects voltage and current synchronously. Indoor and field tests showed that the new APSA-based SIP method can successfully measure the complex resistivity without a synchronous current- or phase-measuring device. Moreover, this method reduces the requirement for synchronization of the transmitter and receiver.