Suunto Dive Manager -Ascent Rate

[mccabejc]

I noticed when I was graphing a dive from my Cobra using the Dive Manager software, some of the ascent rate indicators I saw during my dive are not reflected in the graph data. Does the Dive Manager graph the highest ascent rate encountered in the 10 (or 20) second sample period, or does it just take a snapshot at each interval?

 

[scubasean]

I noticed when I was graphing a dive from my Cobra using the Dive Manager software, some of the ascent rate indicators I saw during my dive are not reflected in the graph data. Does the Dive Manager graph the highest ascent rate encountered in the 10 (or 20) second sample period, or does it just take a snapshot at each interval?

I think it is the latter, and the SDM might show things slightly differently than what you saw on the computer during a dive...Perhaps SDM only sees the individual points, but the computer sees the dive continuously as it happens....

 

[Snowbear]

I had to check mine to get an answer, though I'm not entirely sure what you're asking.
On the actual graph, the actual "indicators" were shown on the screen to the right of the graph. I had to pull up the wild Deception Pass dive where the upcurrent blasted us to the surface to have the little blue diamonds (ascent rate too fast SLOW DOWN alarm) show up on the graph itself. Is that what you're asking about?

I included the screenshot of the graph of that dive...

 

[maractwin]

Having written a program to download dive data from Suunto computers, I've got a pretty good idea what they are doing.

For each sample (20 seconds for most computers) it records a single depth, and whether an alarm was reported during that period. For each of the eight possible alarms (ascending too fast, surfaced, violated ceiling, etc) it just indicates if that alarm was reported during that 20 seconds.

During the dive, depth and alarms are re-calculated more than once a second. To save memory, what is saved for download is much less. That means that you will see some things on your downloaded profile that don't show the same as what you saw on your dive.

The tissue loading is not part of the download, but re-calculated on the PC based on the downloaded samples. So it can also be different.

-Mark

 

[jamiei]

Mark is right on. I would recommend changing the sample interval from the default 20 sec to 10 sec and you should have more of an accurate representation of your actual dive. Just keep in mind that it will cut your dive memory in half but its well worth it... you'll just have to download it more often.
jamie

 

[mccabejc]

To clarify my question:

As you are ascending, your ascent rate is indicated by a set of bars on the right hand side. As you ascend faster, more bars appear. If you exceed the maximum rate, a STOP bar appears.

My computer is set for a ten second sampling interval. So the computer samples the various parameters (pressure, depth, etc.) at a point in time, then again 10 seconds later. Let's call those times A and B.

If, in between times A and B (let's call it A + 5 seconds) I am ascending, and an ascent rate bar appears on the Cobra, then goes away two seconds later, will the downloaded data show that a bar appeared in the interval between A and B, or will it be lost because it didn't happen exactly at the sample times (A or B)?

 

[maractwin]

To clarify my question:
My computer is set for a ten second sampling interval. So the computer samples the various parameters (pressure, depth, etc.) at a point in time, then again 10 seconds later. Let's call those times A and B.

If, in between times A and B (let's call it A + 5 seconds) I am ascending, and an ascent rate bar appears on the Cobra, then goes away two seconds later, will the downloaded data show that a bar appeared in the interval between A and B, or will it be lost because it didn't happen exactly at the sample times (A or B)?

If you exceeded 4 bars on the ascent rate and got a SLOW alarm, this will be reported in the download. Otherwise, it will look at your depth at point A, how much higher you are at point B, and assume you ascended steadily during that 10 seconds and show the number of bars that indicates. However, you may have moved slowly for the first 8 seconds, then sped up for the last 2 seconds to have 4 bars showing, but the profile on your PC wouldn't know this.

-Mark