I have used two Ad5933 evaluation boards to collect impedance data from both the arms of human body. I have acquired data in time domain fixing the measurement frequency at 50 kHz.
However, I am not quite sure about the reliability of my data as I getting a repetitive spike pattern (see the figure) in my data. When I am using a single device this did not happed.
What would be the reason for this scenario?
It is difficult to troubleshoot without knowing lots of details about your setup, the type of electrodes used, where on arms those are placed, distance apart, etc. Do both boards share common ground? Same power supply? Synchronized in any way?
Im using ECG electrodes with contact area greater than 4 cm^2. The arms are places apart no contact of each other. There are 2 separate Ad5933 evaluation boards with separate power supply and ground to each board. At the current setup I haven't synchronized two boards and each board is separately operated by a separate microcontroller.
First thing to try would be to ensure that both boards share common ground. Then to look how much cross talk there is between the excitation on one board and the input on another.