On 12 May, 2017 - Davide DB wrote: > Hi, > > While thinking to the work on oxygen sensor data you are doing, I had > a couple of somewhat foolish thinking. > > In eccr mode the unit is working at a given setpoint for part of the > dive. The set of ppO2 values from the three sensors will follow the > setpoint. the set can be said to be precise if the values are close > to the average value of the quantity being measured, while the set can > be said to be accurate if the values are close to the true value of > the quantity being measured, aka the setpoint. > > So my question is. Do you think will be possible to analyze those data > set (each data set is one sensor) to understand if there is one sensor > which show a different behaviour while measuring the ppO2? > Formerly, from my ancient college studies, I was thinking to the > variance but it express variation respect the dataset average value. I > think it's really a question of "accuracy". > I wonder if we can have a sort of accuracy of each sensor respect the > setpoint for each dive and maybe during the time I can spot an aged > sensor... > > I'm realizing that the above doens't fit in mCCR mode where you do not > have precise setpoint. So I had another foolish thinking. > > Perhaps more simply we could just correlate sensor readings trying to > spot if there is always a sensor value which distances from the > others. Maybe after several dives I could find that the same behaviour > comes from the same sensor. Again I could spot an aged sensor. > Something similar to the controller's voting logic but applied after > the dive to the entire dataset which we have. > > Maybe it's something so obvious that already other people tried to do > something like this proving it wrong. > > l go dive.
I have bin thinking about the same problem, and how it might be possible to try to detect sensor degradation in a early state, and I think this would be a cool and useful feature, but its its only useful for a selective few, and will be pretty tricky to implement. One would for example be required to "log" when you replace a sensor, to suppress false positives. On the up side, its a feature which is really unlikely to cause bugs for "normal" users so its pretty safe to add to the code base. I did some playing around with different metrics, but either the sensors are way too good in my test data, or I did just draw a blank on the thinking department. I think I should plunder all the ccr data I can on the next dive trip and try to figure out any better metrics to detect misbehaving sensors. //Anton -- Anton Lundin +46702-161604 _______________________________________________ subsurface mailing list [email protected] http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
