API redesign progress

[Artur Wroblewski]

On Thu, Jul 5, 2012 at 4:21 PM, Jef Driesen <jefdriesen at telenet.be> wrote:
> On 2012-07-04 19:10, Artur Wroblewski wrote:
>>
>> On Wed, Jul 4, 2012 at 4:53 PM, Jef Driesen <jefdriesen at telenet.be> wrote:
>> [...]
>>>
>>> Now that we are discussing major api improvements, let's also have a
>>> look at the sample parsing api.
>>
>> [...]
>>>
>>> What else should we support?
>>
>>
>> Additionally, my dive computer stores the following on sample level
>>
>> - gradient factor (of leading tissue)
>> - ppO2 (there can be multiple O2 sensors data stored by other computers)
>> - cns
>>
>> See also: http://www.heinrichsweikamp.info/read.php?2,8503,8553 - the
>> custom
>> functions documentation shows what data is stored by OSTC (i.e.
>> divisor options
>> for temperature, deco, cns, etc).
>
>
> I think we can consider adding ppO2 to the list of supported types. It's
> probably mainly relevant for rebreathers, where the traditional concept of
> gas switches doesn't exist and the actual breathing gas changes
> continuously. For open circuit and also semi-closed I think, there is no
> ppO2 sensor and I assume the value just gets calculated from the
> pre-configured gas mix and current depth?

It is for rebreathers indeed. You will have averaged (I believe)
ppO2 from multiple sensors, but I suspect some computers
might report ppO2 from all sensors on top of that. Note, that
some of sensors might be in error.

(please note I am not a CCR diver)

> For the other two, I'm not so sure. The gradient factors are very specific
> to the decompression model,

Maybe... but I wonder how data from VPM-B + GFS combination
is being stored

    http://www.hhssoftware.com/v-planner/vpmdetail.html

:)

> and cns values can be calculated.

You can't if you don't have residual oxygen load
from previous dive (i.e. removed dive from logbook).

Also, CNS depends on the pressure, so your dive
computer _might_ calculate it in real time (useful
on altitudes different than sea level I suppose?).

I know you can estimate (or recalculate) a lot of values,
but I am interested in what my machine reported to me
at given time and depth. I am _not_ interested what some
application thinks, even if it provides quite accurate
information. Actually... I am interested in the dive computer
data when it is innaccurate. :)

[...]

Regards,

w