Multichannel impedance measuring method

摘要

This publication contains a multichannel quadrupolar impedance measuring method. With the help of the method, the impedance measurement can be performed in multichannel fashion with regard to both the voltage measurement and the current supply. The method is especially suited for investigating dynamic changes in the impedance, since the method makes it possible to measure the impedance at the same time from more channels than with the previously known methods. The method is based on identification of the current being supplied. The current being supplied to several different connections is encoded, for example, with currents of different frequency, so that from the voltages which have been measured one can identify the signal in each feeding channel and thus can compute the impedance between the measurement pair of each current feed and obtain information as to the variation of the impedance in different parts of the object being measured.