[PATCH] Visualisation of individual oxygen sensor data for CCR dives

[Anton Lundin]

On 09 April, 2017 - Willem Ferguson wrote:

> Currently Subsurface only explicitly accommodates the Poseidon MKVI
> and the APD Inspiration family of rebreathers, having two/three
> oxygen sensors by default. The reason is simply: these are the
> equipment mostly used by local divers here. Since rebreathers often
> download only one dive at a time (one dive = one complete dive log
> file), a normal dive list-oriented download is not relevant. There
> is not the equivalent of a libdivecomputer for these CCR uploads and
> we import the MKVI and APD dives through the text file import
> mechanism. Currently, several third party manufacturers use
> Shearwater equipment as the controllers for CCR equipment (e.g.
> Hollis Prism). The addition of Shearwater-generated CCR imports will
> be the next quantum step for making Subsurface accessible to CCR
> divers. There are some problems with respect to the import of CCR
> dives:
> 
> 1) Since there is not the equivalent of a libdivecomputer, we are
> dependent on doing the inital download from CCR to text file using
> proprietary software that comes with the equipment (mostly
> Win-only). Extremely inconvenient. Then import from text to
> Subsurface.

The reason APD and MKVI data isn't imported via libdivecomputer has
nothing to do with it being from a CCR.

libdivecomputer is designed to talk directly to dive comptuters and
read out that data, mean while the APD files are exports from APP log
vewer, and libdivecomputer is the wrong tool for parsing text files.


Subsurface imports lots of non CCR data via other methods than
libdivecomputer, and Subsurface will happily import 3 o2 sensors from a
OSTC 3/2/3+ with o2 sensors attached.

 
> 2) I do not know how many Subsurface users actually log CCR dives. I
> know of four users in our country. Clearly a pretty small user base.
> There has been no correspondence from CCR divers on the mail list,
> so we do not know in which ways to improve the existing code.
> 
> There is a possibility that the extension to Shearwater may be very
> simple, depending on whether Jeff includes sensor data in
> libdivecomputer, otherwise it may be a bit more complex.

Shearwater computers stor the "computed" Po2 value, and the mV value of
the sensors. The computer also stores a "calibration value" of unknown
unit.

My reverse enginerring of this calibration value unit have given me the
following formula:

po2 = mv * (cal_value + 1024) / 100000.0


It produces resonable po2 values, but it still might just be bogus.


//Anton


-- 
Anton Lundin	+46702-161604