Wrong Depth in JDiveLog 2.16

[Anonymous User]

Hello,

I've just tried the last release on JDiveLog and find something wrong between the depth in the OSTC 2N logbook and the depth in the program.

I think there is an adjustment with the atmospheric pressure but it's just a supposition...

For example:

Logbook OSTC:
- 61.69m / 975mbar / 6.5° / 44:12 min
JDivelog
- 60.38m / no pressure information?? / 6.5° / 44.2 min

Someone has the same problem?

Thanks!

[wooflock]

Yes i have seen the same thing.
Had a dive that registered 50.12m on the OSTC and 49.88m or something similar when exported to JDivelog.

I found the reason in my case to be that the OSTC records the deepest value it has reached, and stores that in memory separatly.
WHen you download the data however you get the data for every interval that has been stored. If for example the interval is every 20 seconds and you are at 49.9m then lower you arm so the computer reaches 50m, then raise your arm before the computer stores this new depth. for the 50m depth to be transfered to JDivelog it has to be stored in a datapoint that gets exported, so you have to be at your max depth for at least the time it takes for the OSTC to store an extra position, and it happens every 20 seconds or 10 seconds.. dont remember the interval value right now.

[Solodiver]

Known bug in JDiveLog for some time now...

[dmainou]

It has to do with the salinity. 2.16 allows you to adjust it so make use of that function to fix it.

[Solodiver]

dmainou - could you please explain how to use this feature? Extra - Fix Salinity seems to me as a general setting and not depended on single dives? I usualy dive in fresh water, salinity set to 1,0 and all the depth in JDiveLog are wrong...

[dmainou]

Hi Jan,

Ctrl + Alt + S or top toolbar > Extra > Fix salinity

Jdivelog downloads the raw data from the sensor you just need to apply your choice of salinity adjustment.

D

[dmainou]

BTW, it wont match 100% due to sampling issues but close enough.

That is your max depth may have occurred at t+11s whilst the sample only shows the depth at t0 and t1

[Solodiver]

Thx mate, but as I wrote above: This seems to be for all dives in the logbook!? Does not make much sense IMHO. Why is it not using the value stored by OSTC? All the depths in the OSTC logbook seems to be correct and to be the same as in other tools but JDiveLog.

[dmainou]

Just select the one dive at a time.

I believe that the download protocol did not include the salinity. Thus it downloaded the available data.

[Solodiver]

Mate, have you ever used this function and checked the result? Lets just agree it is not working or still a bug.

As I wrote before, I've salinity set correct and it is still wrong. No need to adjust as I do fresh waters dives mostly. Other tools including the OSTC shows correct depth...

Thx,
Jan

[dmainou]

have you submitted a bug?

[Solodiver]

No

[dmainou]

It only changes the depth for the dives you have selected.
You'll need to play with it to understand the logic.
It simply divides or multiplies the sensor reading by an adjustment factor. You've been involved in the multiple discussions of what affects the pressure reading so I'm not going to re explain it.

On the other hand, if you are convinced that it doesn't work and that it has a bug then you are sort of barking at the wrong tree by posting in the HW forum when the JDiveLog SVN is probably more adequate.

D

[neutral]

Hi guys,
the phenomena of differences between the stored maximum depth of a dive in the ostc and the read-out logfile is simple to explain: the OSTC stores the maximum depth when it is reached. this means permanently. The log process generates a data set (depth, time, deco) every 6 seconds (in OSTC standard setting). When the maximun depth is reached in between two logging periods and the duration was shorter than 6 seconds, you will not see this "real" maximum depth in your logging software p.e. JDIVELOG.

HNY
Neutral

[Solodiver]

Sorry this is most likely wrong - as written above and in several other posts any other diving log software displays the same depth as the internal log book...

[scubatinoo]

Even in MacDive are differences! Not in the Depth, but in the Dive Time:

On OSTC i have 42:18, but Mac Divereports me 46:10... funny!

Something else i've discovered yet: In JDiveLog --> Dive Details under comments it is written "Computer Einstellungen: ZH-L16 GF CC 25% / 85%" but i was diving "ZH-L16 GF OC 25% / 85%"

Guess there are still many things to improve in JDiveLog, but it works already nice.

[nakatomi]

MacDive (2.1.1) uses the max depth recorded in the logbook of the OSTC, which is already adjusted to the configured salinity.
This is the correct way to do it of course. If the depth is taken from the samples (the way Jdivelog does it) it will not factor in the salinity.

Regarding the dive time, you are correct there. MacDive uses the raw data to calculate the dive time, which includes the delay after surfacing.
If I remember right, that would have been 4 minutes by default.
I´ve set it to 30 seconds on the OSTC to avoid this issue.
Thinking about it, I will send Nick and email and ask if he can fix this in a future version.