ZZ Resistivity Imaging Pty. Ltd.
3.8 How does FlashRES collect IP data?
The figure below shows how IP data is collected by the FlashRES resistivity meter. FlashRES collects 4*N voltages for each AB current injection (2*N voltages for two on_time periods, 2*N voltages for the two off_time periods, where N is the number of voltages collected during the on_time or off_time period. These periods are specified on the data collection interface before data collection.) For IP surveys, FlashRES resistivity meter sets on_time=off_time.
For IP surveys, FlashRES system stores all 4*N voltages on a computer where a user can form IP window data, using their own window size criteria later. The FlashRES meter also outputs one Dip value (chargeability, unit in milliseconds) calculated with the following formula:
Von is the average voltage and is calculated from 2*N voltages during two on_times; Vk-off-time1 and Vk-off-time2 are the voltages collected during the two off times. These 2*N voltages during two on_times are filtered with a middle-point filter and an average filter, before calculating the Von. There is no filter used for 2*N voltages collected during two off_time period.
ZZ has in-house programs to convert the full wave IP data into windowed data. Users can specify the number of windows and the number of voltages in each window. Also, there are two sets of ZZ default windowing parameters in this program.