How is the convergence zone modeled in DW?

[Castout]

There's convergence zone modeled in DW as I noted in the mission editor.

So in theory it would be possible to get indirect contact through the convergence zone right? How far down? 1st convergence zone only? 2nd? Third?

It's a simple question please don't answer with an unnecessarily overcomplicated answers. In other words...keep it simple.

[Molon Labe]

It's just an area about 1-1.5nm wide at 30nm intervals where transmission loss is sharply reduced. For sure it goes out to three, I wouldn't rule out a 4th if you can get a loud enough source. Depth doesn't seem to matter at all.

[Castout]

Wow so it's possible to get a contact at 90nm. Though the window is pretty short so it's not possible to track a target at convergence zone. Is this correct?. Thanks.

Got a couple questions. Simple doesn't necessarily mean brief. Just do not go into that doctoral paper discussion. . My head just jams whenever I see a mathematical formula. Beautiful women too. Built that way it seems. LOL

Is indirect detection possible below thermal layer/deep depth in convergence zone?
Is direct detection range better when cruising below thermal layer for detecting a below thermal contact(same layer) compared with cruising above thermal and detecting a contact above thermal(same layer)?

Btw what is a surface duct. How is it different from convergence zone in terms of detection especially indirect detection.

You see I hardly know anything about the sonar environment. So help this poor fellow will you. never too late to learn something.
My questions are both for the game and in RL.
Many many thanks before.

[Molon Labe]

Originally Posted by Castout

Wow so it's possible to get a contact at 90nm. Though the window is pretty short so it's not possible to track a target at convergence zone. Is this correct?. Thanks.

It's actually somewhat easy to track a target in a CZ if you can make a reasonable guess about his course, since you automatically know the range. It's just a matter of getting on his course and matching his speed to hold him in the CZ.

Got a couple questions. Simple doesn't necessarily mean brief. Just do not go into that doctoral paper discussion. . My head just jams whenever I see a mathematical formula. Beautiful women too. Built that way it seems. LOL

Is indirect detection possible below thermal layer/deep depth in convergence zone?
Is direct detection range better when cruising below thermal layer for detecting a below thermal contact(same layer) compared with cruising above thermal and detecting a contact above thermal(same layer)?

I've never seen a cross-layer CZ contact and I don't expect to. That's not to say it's impossible; I don't know enough about the "rules" of the acoustics model to know that. But, the transmission loss across the layer at 30nm is already very, very high so even if it was within the "rules" to get the CZ bonus across the layer, I doubt it would be enough to result in a contact.

In a CV SSP, there is only a slight difference between direct detection ranges above and below the layer. IIRC, ranges are a bit longer below the layer; but, I made that observation before the studies were done by others showing a correlations between depth and detection range, and there is enough of a margin of error there to cast doubt on my observations.

Btw what is a surface duct. How is it different from convergence zone in terms of detection especially indirect detection.

In DW:

A SD SSP has a positive gradient above the layer (the surface duct) and a negative gradient below. You'll get long detection ranges above and short detection ranges below.

A CZ SSP has a surface duct above the layer and a sound channel below, in addition to having convergence zones modeled every 30nm. Detection ranges are long both in the duct and in the sound channel.

As for real life, DW is fairly close in the surface duct environment; a surface duct really is a zone of positive gradient above the layer where the sound bends away from the layer and refracts along the surface.

A real life CZ has very little resemblance to a DW CZ or DW CZ SSP. CZ's don't necessarily form at 30nm intervals and don't occur at all depths simultaneously, but at specific bands in 3-dimensional space (usually--or perhaps always?--near the surface). The SSP also isn't possible without a hell of a lot of excess depth, but a shallow bottom does not prevent the SSP from forming in DW.

[Castout]

Wow thank you for your explanation bear with me as I have to confirm some of the answer to make sure I don't get it wrong.

Originally Posted by Molon Labe

I've never seen a cross-layer CZ contact and I don't expect to. That's not to say it's impossible; I don't know enough about the "rules" of the acoustics model to know that. But, the transmission loss across the layer at 30nm is already very, very high so even if it was within the "rules" to get the CZ bonus across the layer, I doubt it would be enough to result in a contact.

So I take it that convergence zone contact across layer is actually not really possible but convergence zone contact on the same layer both below and above thermal layer is possible i.e convergence zone contact can happen below thermal layer.

Originally Posted by Molon Labe

A real life CZ has very little resemblance to a DW CZ or DW CZ SSP. CZ's don't necessarily form at 30nm intervals and don't occur at all depths simultaneously, but at specific bands in 3-dimensional space (usually--or perhaps always?--near the surface). The SSP also isn't possible without a hell of a lot of excess depth, but a shallow bottom does not prevent the SSP from forming in DW.

Now I'm a bit confused so convergence contact in RL can only happen near the surface? while in DW convergence zone contact can happen below thermal layer?

[Dr.Sid]

Check this thread:
http://www.subsim.com/radioroom/showthread.php?t=117814

I'm not sure if I tested it but I think you wont get CZ contact from under the layer. It should be possible and zones of focused sound should go deep. But it's quite complicated, and what more it depends on frequency a lot.

As for DW, I simply suggest you try it. My guess is they won't go under the layer.

[Molon Labe]

Originally Posted by Castout

Wow thank you for your explanation bear with me as I have to confirm some of the answer to make sure I don't get it wrong.

So I take it that convergence zone contact across layer is actually not really possible but convergence zone contact on the same layer both below and above thermal layer is possible i.e convergence zone contact can happen below thermal layer.

Well, if Sid is going to dispute it, I'll say that it's possible that I'm wrong. But I don't think I am. To the best of my recollection, I've observed CZ contacts on both sides of the layer.

Now I'm a bit confused so convergence contact in RL can only happen near the surface? while in DW convergence zone contact can happen below thermal layer?

Well, I'm confused myself, hence the question mark. I know that propagation models will show sound paths converging in and around a sound channel; what I'm not sure about is whether these are called convergence zones or if they have another name. I've never seen them identified as such on anything I've read on the subject.