Dive Computer Technology?

[Kondado]

I'm answering my own question...

I found this thread Sunnto RGBM, what is up with that? - DIR Explorers

Seems there's only one DC - the HS Explorer - which implements a true RGBM. That was in the year 2006 but I guess little has changed since then. Suuntos RGBM seems more a marketing thing... quite sad that is, since I actually believed in it. On the other hand, up until today I have no true complaints to my Suunto D4 (for sure there are and will always be better DCs, but more expensive too).

Anyway, more answers are always appreciated.

 

[Kern]

Hello all...

I know this thread is quite some months old, but I preferred to not open a new thread so that it's easier to understand why I am asking what I'm going to ask...

And the question is: if Liquivision says that current DCs aren't able to cope with a "true" bubble algorithm/model, what do the Suunto DCs do when they use the RGBManagement?

This is what Bruce Wienke has to say on page 12, bullet 4 of RGBM ALGORITHM OVERVIEW: CONCEPTS, BASES, VALIDATION, TESTING AND REFERENCES.....

its a "modified RGBM recreational algorithms (Haldane imbedded with bubble reduction factors limiting reverse profile, repetitive, and multiday diving), as coded into Suunto, Mares, Dacor, ABYSS, GAP, HydroSpace, Plexus decometers, lower an already low DCS incidence rate of approximately 1/10,000 or less. More RGBM decompression meters, including mixed gases, are in the works".

I specifically ask for the Suunto-RGBM since from what I've read the Bühlmann ZH-L8 ADT isn't a true bubble-model but it's more sort of a "bubble-patched neo-haldanean model".

No, Buhlmann is a single phase neo haldanian algo. "M" values would be the only thing you could possably call a hack/patch.

Possibly everything I've supposed is wrong, please bear with me.

Actually the final question would be, as of today (June 2010) is there any divecomputer which has a true bubble model?

Thanks

Sure, the X1.

Seems there's only one DC - the HS Explorer - which implements a true RGBM.That was in the year 2006 but I guess little has changed since then. Suuntos RGBM seems more a marketing thing... quite sad that is, since I actually believed in it. On the other hand, up until today I have no true complaints to my Suunto D4 (for sure there are and will always be better DCs, but more expensive too).

Anyway, more answers are always appreciated.

I'm not sure I believe this. Got a source. See the name of the DC manufacturer I'v highlighted in the excerpt of Wienkes article.

 

[Kondado]

No, Buhlmann is a single phase neo haldanian algo. "M" values would be the only thing you could possably call a hack/patch.

You perfectly resolved all of my previous doubts. There's just one more question which now arises; you say it's a "single phase neo haldanian something", so... does that mean it doesn't take bubbles into account in either way?

I tought I read something about that... well, somewhere.

Is there any Buhlmann variant which does the bubble-math?

Thanks.

(PS: The ADT seems to stand for "adaptive" and takes the temperature differences during a dive into account, i.e. slower off-gassing because of vasoconstriction at the end of the dive.)

 

[ijdod]

I don't mind discussion, I don't actually consider it trolling.

Well, I'm no expert on these things, but when I looked into such things, the consensus seemed to be that OLED need more power than an LCD. Do you leave your backlight on during the entire dive, I cant remember ever turning mine on during an OW daytime dive.

One of you is talking about the old-school reflective LCD, which use very little power, and usually uses reflected light to make it readable. A very low power backlight could also do the trick. This is the technology used in digital watches, and most dive computers.
The other is talking about a modern color LCD, which in itself doesn't use much, but requires a fairly power hungry backlight. This is the technology used in laptop screens, PDAs, most smartphones, and dive computers like the Mares Icon HD. All pixels are lit from behind, black is made by blocking the light.
OLED is a fairly recent development, and is found in dive computers like the Liquivision, Uemis Zurich, the OSTC en some others. OLED typically uses less power than the color LCD mentioned above, but (way) more than the reflective LCD.



That is in fact my point. You can load any neo Haldanian such as Buhlmann onto any of today's crop of computers. There are however very few presently with the power to run a fully iterative dual phase algorithm in real time. So if VPM-B using V-Planner is my preferred desktop software, & I want a DC that is capable of running that same algorithm, it need's to have a more powerful CPU to do so.



Stop believing, start knowing. Sorry couldn't help myself, but that's not the way an X1 works.[/QUOTE]

 

[Kern]

You perfectly resolved all of my previous doubts. There's just one more question which now arises; you say it's a "single phase neo haldanian something", so... does that mean it doesn't take bubbles into account in either way?

I tought I read something about that... well, somewhere.

Is there any Buhlmann variant which does the bubble-math?

Thanks.

(PS: The ADT seems to stand for "adaptive" and takes the temperature differences during a dive into account, i.e. slower off-gassing because of vasoconstriction at the end of the dive.)

Sorry, algo is just me being too lazy to write algorithm.

Buhlmann is single phase, it only accounts for gas dissolved in tissues. It does no bubble math. Bubble algorithms are duel phase, they take free gas (bubbles) into account as well as gas dissolved in the tissues.

ADT takes temp into account. So it knows the water temp, how does it know if I'm wearing a 3mm shorty or a dry suit with heavy underwear. That is, it's adapting to the water, not my body. Sounds like more marketing nonsense to me.

 

[Kern]

Hi Kondado, I'v been thinking about what I'v said about the Buhlmann algorithm & I thought I should elaborate a little. It only pertains to the raw, "vanilla" (unaltered), recreational algorithm.

When doing staged deco dives, most who use Buhlmann these days do in fact apply a patch to alter the output & therefore the shape of the curve. Gradient Factors are applied to raw Buhlmann to change the profile from what is often known traditionally as a bend & mend, come up fast & off gas slowly at a shallow depth model. To one with deeper stops, so you ascend slower & a little less time is spent off gassing in the shallows.

The right Gradient Factors can turn raw Buhlmann curves into something similar to those a bubble model would produce.

 

[Kondado]

I see. Thanks.

In the following days I'll be hopefully the proud owner of a copy of the Bühlmann book (german 5th edition), which I ordered last friday. I know it lacks some parts of the important information but I think it can be quite interesting to read from a "deco-historical" point of view and to get some insight into the basics of deco-theory.

 

[Kondado]

I found this in Bruce Wienke's "RGBM ALGORITHM OVERVIEW:
CONCEPTS, BASES, VALIDATION, TESTING
AND REFERENCES"

The HydroSpace EXPLORER is a mixed gas decompression meter for technical and
recreational diving, as are the ABYSS and GAP software vehicles. The EXPLORER is the first ever
full RGBM computer for all diving.

Just for the sake of completeness. Seems to me a bit like a contradiction with the other excerpt Kern posted... but well...

 

[Kern]

I found this in Bruce Wienke's "RGBM ALGORITHM OVERVIEW:
CONCEPTS, BASES, VALIDATION, TESTING
AND REFERENCES"

The HydroSpace EXPLORER is a mixed gas decompression meter for technical and
recreational diving, as are the ABYSS and GAP software vehicles. The EXPLORER is the first ever
full RGBM computer for all diving.

Just for the sake of completeness. Seems to me a bit like a contradiction with the other excerpt Kern posted... but well...

I love it, not only have you found a source for what you were told, its in the article I used to contradict it.

What can I say, its RGBM, its proprietary, outside of Wienke & the manufacturers, who can know the truth?