Suunto Cobra missing PSI information

[anry]

Hello,

Recently I've moved to the Mac world and my dive buddy recommended MacDive. I'm so glad I can run native OS X application to manage my logs. Thank you guys for nice work.

I'm diving with Suunto Cobra (ver.1 with serial port http://www.suunto.com/en-us/Products/Di ... nto-Cobra/)
MacDive version 1.5.3
First I've successfully migrated my old dives from Suunto Dive Manager to MacDive. Then I tried to import new dives from Cobra and noticed that pressure samples are missing. When I look at "Raw" tab "Pressure" column is empty. All other parameters are imported successfully.
I'm using USB/Serial cable with Prolific driver (http://sourceforge.net/projects/osx-pl2303/)
I went ahead and run vyper program to download raw data. It successfully generated LOG and DMP files.
Nick, TnT I would appreciate if you can look at data and see if there is problem with MacDive or something else.
I'll send files to your e-mail.


Thank you,

Anry

[nick]

Hey,

The cobra doesn't record pressure information per-sample. It only records the start and end readings.

So nothings wrong - it's just a limitation of that style of device.

[anry]

Nick, thank you for really quick response.
I think Cobra records pressure information per sample. Suunto dive manager was capable of pulling that info from Cobra and building nice SAC graph for the dive. BTW these data were successfully imported into MacDive from SDM.
It is only new dives I'm trying to download from Cobra with MacDive are missing PSI samples.
I'm not familiar with VYPER.LOG format so can't tell if PSI samples are present there.
I would be glad to help you finding these data in Cobra protocol. Can you give me a hint how to run USB packet capture on Windows XP and can provide you with Cobra <-> SDM protocol capture.

What I know for sure Cobra is missing temperature information per-sample. Only temperature at beginning of dive, at max depth and end of the dive are recorded.

Appreciate your dedication to this project,

Anry

[nick]

Nick, thank you for really quick response.
I think Cobra records pressure information per sample. Suunto dive manager was capable of pulling that info from Cobra and building nice SAC graph for the dive.

No, it doesn't - this is a common misconception because of Suunto Dive Manager. SDM "guesses" those values. They don't exist, and it's not accurate. Especially for SAC rate where things like your effort in a current etc will make a big difference and cannot be taken into account.

What I know for sure Cobra is missing temperature information per-sample. Only temperature at beginning of dive, at max depth and end of the dive are recorded.

This is the same deal as pressure. It is just not recorded per-sample.

[anry]

Wow. Thank you for enlightenment. Sneaky SDM!

[TnT]

You can notice this when you click the recalculate button in the Air Consumption tab. It will ask you whether to simulate or not. Depending on whether you answer yes or no, SDM will interpolate the pressure linearly (and thus a non constant SAC graph), or interpolate the pressure assuming a constant SAC (and thus a non linear pressure graph). Note that SDM will ask this question only once (per dive), and you can't undo your choice as far as I know.

[romer628]

I ran into this problem too. I just bought an air integrated computer for the purpose of being able to see this data. When I found out it wasn't being recorded I was rather upset. I contacted Suunto today and found out that the Cobra does in fact record pressure, but there is a bug in their software. They suggested I try to use Suunto Dive Manager version 2. My dive shop found an old copy in the back and I downloaded it on Parallels and imported my dives. Sure enough, the pressure information was there, just SDMv3 and MacDive both can't seem to see it. I was able to export the files from SDMv2 and import them into MacDive successfully including the PSI data.

I can provide the SDE file if that helps.

Overall though I'm not to thrilled with the Cobra. After talking to my dive shop I think I might be swapping it out for a Vyper Air instead. Unless somebody else has a better suggestion.

[nick]

It records pressure, but not pressure per sample.

[romer628]

I meant per sample. When I looked at the raw data when downloaded through SDMv2 it does in fact show pressure per sample.

However... I suppose that it's possible that it actually saves the simulated pressure data to the raw log, whereas the newer version does not. When I looked closer at the dive log I don't see any evidence of the shared breathing exercise I did on one of the dives. Since my buddy and I were both breathing down his tank my pressure wouldn't have changed.

[nick]

This is about right. There really is nowhere for the pressure to exist in a sample. The samples/memory of these devices is very simple - it's simply a depth delta. That's it.

If you have a look at the information SDM has generated, you can tell it's not real.