Buhlmann ZHL-C / B & Divelogs Divesoft

Robert Helling helling at atdotde.de
Tue Nov 30 06:42:14 PST 2021


Markus,

> On 30. Nov 2021, at 03:14, Markus Ehmann via subsurface <subsurface at subsurface-divelog.org> wrote:
> 
> One question I have is about the Buhlmann used for planning as well as calculated TTS when analysing a divelog. The settings don't specify if this is the ZHLC or ZHLB.
> Can you tell me which one is used or if I may missed the option to switch to either one?
> Depending on the dive computer used, the differ during the dive and it would be neat to align planning and profile as close as possible.
> 
> 
As you can see in https://github.com/subsurface/subsurface/blob/1e527fb9f01388df2248a90efc7de26c90faec75/core/deco.c#L84
Subsurface uses the ZHLC coefficients as should be the case for dive computers (-B is to generate tables).

For the detailed coefficients, see for example http://www.nigelhewitt.co.uk/stuff/aab.jpg. The a coefficients in the -C model are about 10% smaller in the middle tissues and since

 tolerated = (tissue_inertgas_saturation - buehlmann_inertgas_a) * buehlmann_inertgas_b;

this means that tolerated is bigger. That means that for given tissue saturation the ceiling is a higher ambient (tolerated) pressure i.e. deeper. So this version is a bit more conservative, but the difference is not too big.


> Also, having recently added a Divesoft Liberty, I noticed that the import of divelogs works only with the .dlf files.
> With their recent 2021 hardware update, Divesoft added Bluetooth functionality. So I wondered if you have any plans of adding a direct Bluetooth import for this computer to subsurface as well?
> 

I don’t know. As far as I know, none of the developers have such a computer. And implementing this would be helped substantially if there were information on how the protocol is supposed to work (most likely provided by the manufacturer).

Best
Robert
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 833 bytes
Desc: Message signed with OpenPGP
URL: <http://lists.subsurface-divelog.org/pipermail/subsurface/attachments/20211130/f79ddbaf/attachment-0001.sig>


More information about the subsurface mailing list