In developing a medical application, I have investigated the use of the ADuCM350EKSP for monitoring respiration. The configuration of the software and data obtained are shown in the attachment. The sensor consists of a chest strap with two conductive rubber 3"x1" electrodes right and left of center on the chest. The electrodes are connected directly to LK3 and LK4 on the Switch Mux Config Board.
The table shows 13 repeats of data taken at deep inhale and 12 repeats at deep exhale. The data is listed in the order it was obtained, usally with an interlude of 1 min or more between data pairs (magn & phase).
Note that magnitude 6972 is repeated twice. Each time the number behind the decimal is 193 raising a question about the validity of data behind the decimal point. Moreover, both instances of 6972 are paired with a phase of -17.643. Physiological measurements do not repeat so precisely. That's obvious from the scatter of the other measurements among the 13 inhale pairs and 12 exhale pairs.
This is not the only occurrence of the same nature. The following also repeat:
Magnitude 7093 always with .891 behind the decimal point and always paired with phase -18.264
Magnitude 7171 always with .907 behind the decimal point and always paired with phase -17.256
Magnitude 7020 always with .45 behind the decimal point and always paired with phase -19.088
Magnitude 7015 always with .454 behind the decimal point and always paired with phase -19.249
The data shown in the table was created randomly and not selected. Out of 25 pairs of measurements, 10 are repeats. This suggests that in the range I investigated there may be far fewer than 100 possible outcomes. That further suggests that listing more than 3 significant places is not justified by the hardware or software.
Can anyone suggest a cause to explain these observations?