More Uwatec Aladin TEC2G Log Data

[Jef Driesen]

On 2016-08-05 00:03, Thomas Gschwind wrote:
> I am using Subsurface and it reports all my salt water dives deeper 
> than
> they really are. So I downloaded the latest libdivecomputer sources and
> looked at the code. The tec2g_header claims that the salinity setting 
> of
> this dive computer is not supported.
> 
> After looking at the dumps included in my SmartTRAK log where the dives 
> are
> correctly reported (SmartTRAK is nice enough to store the original dc
> data), I am most certain to have located the salinity field in byte 62 
> of
> the header.  Another indication is that it is also bit 0x10 as it is 
> for
> the others (see get water in uwatec_smart_parser_cache).
> 
> Just tried out setting the salinity field to 62 and works perfectly 
> fine
> for me.
> 
> Similarly, the timezone field most likely is 16. However, that one I 
> cannot
> test so well because the immersion time seems to be relative to the 
> dive
> computers system time which seems to be missing in the SmartTRAK logs. 
> But
> manually looking at the time zones, it matched for the first 50+ of my
> dives.
> 
> I also figured out the max ppo2 configuration and partially the tissue
> saturation before the dive --- if anybody is interested that data as 
> well.
> See 
> http://tomsblog.gschwinds.net/2016/08/uwatec-smarttrak-and-aladin-tec2g/
> for details.

Your investigation for the timezone and salinity fields appear correct 
to me. Will you submit a patch?

BTW, in your blog you write libdivecomputer "prefers to read the data 
from the dive computer itself", but parsing dives "offline" is fully 
supported too. Take a look at libdivecomputer's dctool application:

$ dctool help parse
Parse previously downloaded dives

Usage:
    dctool parse [options] <filename>

Options:
    -h, --help                 Show help message
    -o, --output <filename>    Output filename
    -d, --devtime <timestamp>  Device time
    -s, --systime <timestamp>  System time
    -u, --units <units>        Set units (metric or imperial)

The "devtime" and "systime" options are there to synchronize the device 
and system (host) clocks. During a download libdivecomputer will get 
those two values, and take care of them internally. But when you intend 
to parse the dives at a later time, you should preserve those two values 
yourself. As you already discovered, smarttrak doesn't do that (it 
stores the parsed date/time, so it no longer need those two clock 
synchronization values). But there is no reason why you can't use the 
values of another download.

# Download the dives:
dctool -l dctool-download.log -f smart download -f raw -o dive.%n.bin

# Get the clock synchronization values:
grep -e systime -e devtime dctool-dowload.log

# Parse the dives (or the ones in your smarttrak database):
dctool -l dctool-parse.log -f smart parse -d $DEVTIME -s $SYSTIME -o 
dctool.xml dive.%n.bin

Jef