On 01 December, 2017 - John Smith wrote: > > > On 1 Dec 2017, at 20:39, Davide DB > <dbdav...@gmail.com<mailto:dbdav...@gmail.com>> wrote: > > Yes I know perfectly how calibration works. I meant how po2 is calculated > from downloaded data. > > Sorry, I wasn’t making myself clear. The point I was trying to make was > wondering how libdivecomputer takes the individual cell calibration into > account as there doesnt seem to be any calibration values in the log file. > > It's a completely different story. > > Am I the only one with a Petrel controller here? Maybe other user can confirm > if their pO2 values are correct. > > I was thinking about whether I could time match data from my AP handset - > which shows PPO2 for each cell against my ext petrel data. The following > graph shows the data extracted from subsurface. > > > [cid:c2b9af0b-0980-493c-b296-7c51e8aff908] > > I know there is a small difference between the two computers, I see that > during calibration, but I cannot see anything major in this particular dive. > > > davide@mobile > > Il 01 dic 2017 7:38 PM, "John Smith" > <nosey...@hotmail.com<mailto:nosey...@hotmail.com>> ha scritto: > > What I do not understand is how this conversion was made the very first time. > I mean how did you reverse engineered those values? I mean did you have a > reference data set (mV, calibration K and resulting po2) to compare against? > Surely every time you run the calibration routine on the shearwater there > should be a new calibration value (calibration k) for each cell. The PPO2 is > then a linear calculation based on this.
In the data we have sensor1-3 mV , calibration values for sensor 1-3, sensor status after voting and the computed average p02 between the used sensors. After steering at those values and playing around with a bunch of different formulas we figured out how to use the calibration values so it matched the data we had from 10 or so different units. Thats how I and Jef reverse engineered it. //Anton -- Anton Lundin +46702-161604 _______________________________________________ subsurface mailing list subsurface@subsurface-divelog.org http://lists.subsurface-divelog.org/cgi-bin/mailman/listinfo/subsurface
