Missing pO2 samples from CCR download [was: 4.7.8: a couple of questions]

[Anton Lundin]

On 22 June, 2018 - Davide DB wrote:

> On Thu, 21 Jun 2018 at 22:57, Anton Lundin <glance at acc.umu.se> wrote:
> 
> > On 21 June, 2018 - Dirk Hohndel wrote:
> >
> > > I am reasonably certain that we can rectify this.
> > >
> > > Please make a copy of your dive data (simply export them to an XML
> > > file), open that XML file, and then re-download from the Shearwater.
> > > In the Download dialog check the two boxes (sorry, English text, I'm
> > > sure you can figure out the Italian version):
> > > "Force download of all dives"
> > > "Always prefer downloaded dives"
> > >
> > > With these options checked it should keep all of your other data like
> > > notes, buddies, etc, but replace the downloaded data with the new
> > > version which we assume will be corrected with the fix in place.
> > >
> > > So this should be reasonably easy to recover from.
> >
> 
> Great Dirk!
> This completely change everything. I always thought it would have delete
> everything.
> I will try ASAP.
> 
> Thanks
> 
> 
> 
> > > > A CCR dive without pO2 samples is like a cake with no sugar. If I
> > > > still have them on my Petrel (I never investigated how many profiles
> > > > it stores) I should import everything from scratch into Subsurface and
> > > > compile everything again. Not a nice perspective for the future. Right
> > > > now I'm diving two/three times per week so the count will increase
> > > > rapidly. I've tons of notes, wrecks positions, all dives have GPS
> > > > locations...
> > >
> > > See above - you should be able to do this without having to manually
> > > re-edit all of this work!
> >
> > I would rather describe it as without the pretty icing on the cake.
> > Every thing else about the profile is correct. Time, depth, temp and so
> > on. The pO2 is just affecting your deco and the monitoring of your
> > rebreather performance. Thats my view on it.
> >
> 
> I respect your point but I run my unit completely manual from the beginning
> so pO2 matters to me. It's a way to monitor my progress and see how the
> Shearwater Buhlmann behaves with the pO2 when I do not use ratio deco.
> 

The result from the Shearwater's deco calculations are still there. Its
just subsurface deco calculations that are bogus.

> > If someone can extract this as one or two sample dives that show the
> > > problem and add words that make enough sense to me, I'll reach out
> > > to Shearwater again to see if they have suggestions. I know I sent them
> > > one of the earliest exchanges on this topic but neither they nor I really
> > > understood the problem and it got dropped
> >
> > The calibration constants stored in the dive header are the default
> > value of 2100, and not the actual calibration constant.
> >
> > First, that caused us to incorrectly convert the mV values from the
> > sensors into po2 values, and the later code did just skip exposing any
> > po2 values at all.
> >
> > Now we fall back to the averaged/voted po2 value stored in a different
> > position in the samples.
> >
> > > > Moreover other questions remained unanswered; In one year my unique
> > > > Petrel was identified as 3 different devices with random number of
> > > > sensors. My logbook is a mess and nobody knows the reason.
> > >
> > > Also something I can ask about if you give me more information.
> >
> > I rarely thing its random.
> >
> > The old code exposed 1 value, the averaged/voted one.
> >
> > Later, we exposed the individual sensor values.
> >
> > Now we will expose the individual sensor values if we can find sane
> > calibration constants, otherwise the averaged/voted one. We will also
> > add a row in the "Extra info" pane saying which one it is.
> >
> 
> I was referring to my logbook. Looking into my logbook I find 4 different
> computers (deviceid it's the same):
> 
> <divecomputer model='Shearwater Petrel 2' deviceid='1a2d46b1'
> diveid='3db7eb77' dctype='CCR' no_o2sensors='1'>
> <divecomputer model='Shearwater Petrel 2' deviceid='1a2d46b1'
> diveid='52d4ba3e' dctype='CCR' no_o2sensors='3'>
> <divecomputer model='Shearwater Petrel' deviceid='1a2d46b1'
> diveid='a6e05a10' dctype='CCR'>
> <divecomputer model='Shearwater Petrel 2' deviceid='1a2d46b1'
> diveid='3db24900' dctype='CCR'>
> 
> Where these differences originate from?
> 1 sensor, 3 sensor, no sensor, Petrel and Petrel 2
> 
> Different Subsurface versions with different approach?

You did choose Petrel some times and Petrel 2 other times. It doesn't
matter, for anything else.

no_o2sensors=1 when we only exposed the averaged/voted, no_o2sensors=3
when we did expose all the cells. No no_o2sensors= from dives where we
didn't expose any o2 sensors.


Not random number of sensors and it wasn't that hard to explain. Not
even close to my definition of a mess (like the call chains in the
mobile app).


> >
> > > > Months ago, given your good relationship with Shearwater, I warmly
> > > > recommended to contact them privately asking info on this nasty
> > > > behaviour of some devices.
> > >
> > > I will look again if there are more emails that I've missed.
> >
> > The devices behave just fine. Its just our reverse engineered code who
> > doesn't work any longer.
> >
> > There has bin some email exchanges, (don't remember who talked to them
> > or when), about how to use the calibration constants and the comment
> > from Shearwater back then was that this is a internal detail they didn't
> > want to say anything about it.
> > The answer might change when someone else asks them, but thats the last
> > thing I heard.
> >
> > I don't have any Shearwater devices nor any contacts at that company. I
> > just stared at the data long enough and figured out a (what later turned
> > out to be a faulty) relationship between them. Later Jef figured out
> > what the real relation ship was which matched the data way better.
> > (To my defence, my formula matched all the test data I had =)
> >
> >
> Two users affected in a very small Subsurface user base. Who knows how many
> units expose the default calibration values?

But it doesn't matter. Its a "internal value no one should care about". 

> Anyway, mine was just a suggestion. No problem at all.
> I will try Dirk suggestion so I can save my old data.


//Anton


-- 
Anton Lundin	+46702-161604