Synchronous primary signal processing for MIMO bio-impedance measurement on several frequencies

The paper presents a way to perform multi-channel bio-impedance measurement on several frequencies applying a special FPGA circuit for fast synchronous primary signal processing. The primary processing involves only additive operations and uses stored data 1) to simplify a possibility to obtain higher resolution of measurement signalpsilas samples V(n) applying AD conversion (mainly) for the differences V(n)-V(n-N) where N is the length of the measurement cycle and 2) to obtain for every n the preliminary results (ldquorawrdquo data based on last N samples) for finding real and imaginary parts (and/or modulus and phase) of electrical bio-impedance for several channels and frequencies so that further signal processing and displaying of final results can be performed with a suitable rate.