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Deep Sound Channel? - 6/10/2021 8:29:51 PM

madavid0

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So, according to the dev's outline of the sonar changes, DSC can't be used by tactical platforms. VDSs can't use it. Only permanent installations. The reason for this was "user feedback" by people knowledgeable of this topic. So...does that mean all the public information on DSC on the Internet is false? The Wikipedia entry which describes the original experimentation was done with a hydrophone hanging off a sailboat is in error? I'm fully willing to admit ignorance on this topic so can someone encapsulate the reason why VDS can't listen in the DSC?

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RE: Deep Sound Channel? - 6/10/2021 10:46:46 PM

thewood1

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https://www.matrixgames.com/forums/tm.asp?m=4975338

Just did a quick search on "deep sound channel". There were a couple other threads, but this one had the most current detail. Not sure if it answers your question, but its a start.

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RE: Deep Sound Channel? - 6/11/2021 3:27:25 AM

musurca

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quote:

So...does that mean all the public information on DSC on the Internet is false?

Thank you for asking this! I had the same thought. Use of the DSC is a feature of various other modern sub simulations, including Sonalysts' "Dangerous Waters." It would be great to hear more information about why the DSC isn't suitable for tactical use.

(& unfortunately this question is not answered in the forum post linked above.)

< Message edited by musurca -- 6/11/2021 3:31:06 AM >

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RE: Deep Sound Channel? - 6/11/2021 11:12:38 AM

SeaQueen

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quote:

ORIGINAL: madavid0
So...does that mean all the public information on DSC on the Internet is false?

No, it doesn't. It just means that it's more complicated than what the game really captures and so they had to make adjustments. The real answer to everything involving sonar is "it depends," and the problem with sonar is that the things it depends on are typically subject to tremendous uncertainty because it's driven by oceanographic variables with sparse data at best. The DSC is real, however to take advantage of it, you need to be either much much deeper or much much louder than what was portrayed in the game's sonar model. CMO DOES NOT numerically solve the parabolic equations and develop a full field transmission loss model for every sonar interaction. If it did, D would be winning all kinds of oceanographic awards, have easily earned his PhD and have a horde of oceanographers worshipping his genius. That's computationally intensive to do, I've done it, it takes a few minutes for the computer to crank. Damn... you make me miss doing ASW analysis... almost.

Instead CMO makes abstractions and simplifications. The DSC is much more of something that you'd see fixed bottom sensors or sensors mounted on the sides of seamounts taking advantage of. Deeper diving submarines... maybe (big maybe). A VDS would need to be really really long to get down in there, though. It's just not a thing.

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RE: Deep Sound Channel? - 6/11/2021 1:52:11 PM

LORDPrometheus

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SeaQueen, as the name would imply, hit the nail on the head. End of the day CMO is about tactics and strategy and focuses on surface and air combat. You also lack things such as convergence zones it's just beyond the design goal of the simulation. CMO is more akin to a very complicated dice based tactical game oweing to it's Harpoon Heritage. Sonar in CMO works (highly simplified explanation) by basically saying "sensor A is here Target B is here check range depth change environmental changes and volume then roll percentage dice to see if there is a detection"

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RE: Deep Sound Channel? - 6/11/2021 3:20:05 PM

Gunner98

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quote:

Sonar in CMO works (highly simplified explanation) by basically saying "sensor A is here Target B is here check range depth change environmental changes and volume then roll percentage dice to see if there is a detection"

I believe that is a gross oversimplification of what CMO does. And it does consider CZs. I'll let the sub pros respond in more depth but I think your statement is off the mark.

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RE: Deep Sound Channel? - 6/12/2021 3:09:59 AM

RoryAndersonCDT

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Sensor detections in Command are not governed by RNG.

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RE: Deep Sound Channel? - 6/12/2021 3:44:48 PM

madavid0

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quote:

ORIGINAL: SeaQueen

quote:

ORIGINAL: madavid0
So...does that mean all the public information on DSC on the Internet is false?

No, it doesn't. It just means that it's more complicated than what the game really captures and so they had to make adjustments. The real answer to everything involving sonar is "it depends," and the problem with sonar is that the things it depends on are typically subject to tremendous uncertainty because it's driven by oceanographic variables with sparse data at best. The DSC is real, however to take advantage of it, you need to be either much much deeper or much much louder than what was portrayed in the game's sonar model. CMO DOES NOT numerically solve the parabolic equations and develop a full field transmission loss model for every sonar interaction. If it did, D would be winning all kinds of oceanographic awards, have easily earned his PhD and have a horde of oceanographers worshipping his genius. That's computationally intensive to do, I've done it, it takes a few minutes for the computer to crank. Damn... you make me miss doing ASW analysis... almost.

Instead CMO makes abstractions and simplifications. The DSC is much more of something that you'd see fixed bottom sensors or sensors mounted on the sides of seamounts taking advantage of. Deeper diving submarines... maybe (big maybe). A VDS would need to be really really long to get down in there, though. It's just not a thing.

So...the public information is wrong? The DSC isn't approximately at 1000m and military towed arrays aren't several km long? I'm sure that in the real world analyzing sounds from the DSC for ocean research isn't a simple task, but we're not talking about complex sounds from thousands of miles away, but sounds generated by large machines moving through the water less than a hundreds miles away.

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RE: Deep Sound Channel? - 6/12/2021 5:52:23 PM

AKar

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Not knowing much at all about sonar in particular, but something about signal transmission more in general, I feel we are mixing some concepts here. I speak as generally as I can here!

Some of the signal emitted above the DSC is certainly entering (or scattering into) the "acoustic waveguide" as it is very nicely described. This would be a function of angles, probably modeled as a point-wave source (Huygens-Fresnel approximation), or something like that. Within the layer, the signal smoothly curves up and, depth allowing, starts to rise again towards the surface.

What doesn't initially enter the DSC must essentially reflect back up. This would likely be detectable as "a first bounce" for a target above the DSC. What enters the DSC + what reflects back up = original signal - losses along the way.

The signal component that entered the DSC would start to smoothly turn up again.

Now, there are two phenomena pushing the wave that entered into the DSC back down: first, the same one that made it initially turn up in reverse, and, second, the reflection from surface layer phenomena. (There could be a bottom bounce as well, creating a reflected signal in such an angle that it penetrates the layer structure with ease, but I shall ignore that for now!)

The signal component smoothly turning back down (that is, not quite reaching the area of sharp change in the properties of acoustic medium) would continue traveling on in sinusoidal fashion until reaching... something. But the signal component actually reaching the layer structure of the sea water would both reflect back down in part, but would also scatter above the layer as a perhaps detectable signal, allowing a faint detection potentially at a very long distance.

The physics of the question revolve around the properties of the sea water in terms of how they layer. And as this is, in general, a question dependent on local conditions, it likely makes this fairly difficult to model, unless calculating a fine grid of local temperature profiles, and the other good stuff.

So, to summarize the nonsense, there should be a scattering component model, a reflected component model, and the wave guide travel model, each interacting, for the DSC! :)

< Message edited by AKar -- 6/12/2021 6:22:03 PM >

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