smtk2ssrf operation

Salvador Cu├▒at salvador.cunat at gmail.com
Fri Feb 10 10:11:28 PST 2017


Good afternoon Alessandro.
Thanks for your feedback, much appreciated.

On Fri, Feb 10, 2017 at 01:11:50PM +0000, Alessandro Volpi wrote:
> Good morning Salvador and Willem.
> 
                ............
>
> I have also observed that in many case there is a 1 minute difference
> between the "Dive time" number in the Info Tab and the Duration" number in
> the Stats Tab. I do not know whether the two variables have a different
> meaning, but I guess that the rounding to integer is once more the cause of
> the discrepancy.
> 
Rounding is probably the expalanation, but Stats tab runs its own
functions and, almost for sure, it's taking time differences from
subsurface's log as it's meant to compute one *or more* dives, while
the duration in the info tab shows the duration as taken from the .slg
file.

> I must point out THAT I AM ALWAYS USING UTC TIME IN MY COMPUTERS, in my
> Galileo device and that I am going to root my Galaxy S7 Android phone in
> order to set also said device to UTC time. The use of localtime is ALWAYS a
> source of trouble ! I might even  guess that a different Time Zone setting
> in the dive computer and in the PC might be the explanation, specially when
> the Windows version is used, since Windows sets the hw clock to localtime
> instead of UTC time, IMHO a very stupid choice ...
> 
Totally agreed.

> Another difference  between the data displayed by SmartTrak and Subsurface
> is the depth. This is due to the different value of the water density
> variable used by the two application for displaying depth. Subsurface uses
> a density value of 1000 kg/cu_m, whilst SmartTrak uses 1024 kg/cu_m.
> i think that the best choice is indeed 1000 . This is good for a direct
> comparison for dives carried out in salt water and in freshwater, as far as
> the decompression issues are concerned. Moreover, if one would prefer
> considering the "geometric depth" instead of "pressure depth" he should
> also understand that 1024 is too low for the Mediterranean Sea and too
> highfor the Baltic Sea.
> 
> Since 1998 I have been using UWATEC dive computer. I started with a Aladin
> Air Z, than I replaced it with a Smart Tec. I then switched to Galileo and
> Galileo Trimix.
> 
> Looking at the data imported with smtk2ssrf I can infer the following
> statements:
> 
>    - smtk2ssrf finds some data format errors in a number of dives carried
>    out with the Aladin Air Z. Such errors probably result in a yellow triangle
>    label being displayed on the subsurface dive graph. I have always found one
>    or more of such labels in all dives including a format error, according to
>    the output of smtk2ssrf. In a small number of dives I have found a yellow
>    triangle label even when no format error has been detected by the import
>    program. I guess that the related events have been actually downloaded from
>    the Aladin Air Z and that they have not thus been generated during the data
>    translation by smtk2ssrf.
I used to dive an Aladin X/Z in the past, in fact, my son is diving a
Pro ATM (although working a serial interface for it is my TODO list
and I can't download from it). The yellow triangles are alarms
generated by the Aladin. If you put the cursor on the symbol, you'll
get the explanation at the bottom of the info box. For me they are
most of time "ascent alarms", but if using air integration, they can
also be "work alarms" or "rbt alarms". Keep in mind that old Aladins
didn't have "warnings" just "alarms". The ascent one is specially
annoying.

>    - The dives whose data were recorded by the Galileo device always
>    include a number of points marked by a red flag with diagonal strip icon. I
>    have observed that the beginning of the "safety stop" is always marked by
>    such an icon. In a large number of dives there is only one of such icons at
>    the beginning of the safety stop. in other dives more than one red flag
>    icon is included. I am almost sure that the related events have not been
>    generated during the data translation, since I have seen that the events
>    marked in smkt2ssrf generated records are exactly the same as the events
>    included in the dive data directly downloaded by Subsurface from the
>    Galileo device.

The little NATO's diver flag is used by subsurface to mark bookmarks,
and, as you point out, you will get much more of them than you really
put while diving.  They are the reason why I told you to keep storing
dives with SmarTrak.
Most of them aren't real bookmarks, but *alarms*. Some of the alarms
stored in an SmartTrak log (well, actually the meaning of the bytes
storing them) are not fully undestood yet by libdivecomputer. This
way, libdivecomputer generates a bookmark for the unknown alarm; if
the user knows it's meaning in a dive, he can edit it in subsurface
or, even, remove it if its a waste of time (as said before with the
annoying ascent alarms in Aladin X/Z).
In the future, libdivecomputer will probably understand this alarms,
so re-importing these dives to subsurface will bring to your divelog
the correct markers (ascent, rbt, security stop begining ...)

>    - I feel that the number of such events is larger than the number of
>    dive bookmarks accidentally generated by pressing a button on the Galileo
>    device. I usually delete such "fake" bookmarks when importing the dive data
>    with SmartTrak. I guess that the deleted bookmarks are still present in the
>    dive_log.slg file but I think that the Galileo device is indeed generating
>    other flags which are not shown in the SmartTrak graphic tools, although
>    they are present in the .slg files. On the other hand I am not 100% sure
>    about that.
>
Most marks in Galileo's seems to be related to the time periods
that SmartTrak shows at the bottom of the profile in that time-line
like item (squeezing my memory, may be confused with datatrak screen),
and don't show on the profile itself.
BTW, Smart and Galileo use the same format, but, probably, Smart logs
less events than Galileo does.

Best Regards.

Salva.


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