Broadband vs narrowband sonar

[Dr.Sid]

Sometimes even you US bubbleheads tell more about Russian subs then about US subs. Sure you know little of them, but then it's much less secret. So I would like to see Russian sonar chief to tell me about typical 688 signature, since that is info no US mariner will give.

Anyway the game must be just so good, that it matches general knowledge, with some additional educational insight. It dos not have to be correct, as long as nobody knows what really is correct.

[Rip]

Originally Posted by Hitman

I don't think that the technology itself is so secret, it's the real world efectiveness of it what is top secret, i.e. what they can or can't detect, what they can or can't hide, etc. Processor power is one thing, but that power might be sufficient if the data the sensors can collect is already detailed enough, or inversely, more processor power might be unnecessary because the current sensor technology can't provide more accurate data to be processed.

Also not all processing is done by those. Not to mention not all signal processing is done by actual processors. Just because the processing power of the early space flights was small compared to what is used today, the problems that had to be calculated and dealt with were anything but simple. Don't get me wrong the digital processing helps but the most classified parts are more related to what we can do and how, not how complex the problems that are faced are. At one time we were forbidden to even say the word Tritium(sp?). That is why if you listen to Sailor Steve's video he took while we rode to Galveston in Neal's car I was telling a story that concerned tracking operations. That was probably cloder to the line than I would normally venture, only because I didn't realize he had audio on his camera. Thankfully I was wise enough to leave out location and time details that probably kept it far enough from "the line" that I can sleep with both eyes closed.

Rip

[Rip]

Originally Posted by Dr.Sid

Sometimes even you US bubbleheads tell more about Russian subs then about US subs. Sure you know little of them, but then it's much less secret. So I would like to see Russian sonar chief to tell me about typical 688 signature, since that is info no US mariner will give.

Anyway the game must be just so good, that it matches general knowledge, with some additional educational insight. It dos not have to be correct, as long as nobody knows what really is correct.

Well said. The fact that you could make a tonal you pick up vary in freq based on speed in the line of sight and using that to tactical advantage adds realism, the specific frequencies and the amount of shift not so much so. 98% of the really classified stuff would have zero tactical effect on how you operate your platform. Probably half of the remaining stuff that is classified can be guessed at effectively. No value in everything being exactly technically accurate.

[Shadowmind]

Originally Posted by Rip

Also not all processing is done by those. Not to mention not all signal processing is done by actual processors. Just because the processing power of the early space flights was small compared to what is used today, the problems that had to be calculated and dealt with were anything but simple. Don't get me wrong the digital processing helps but the most classified parts are more related to what we can do and how, not how complex the problems that are faced are. At one time we were forbidden to even say the word Tritium(sp?). That is why if you listen to Sailor Steve's video he took while we rode to Galveston in Neal's car I was telling a story that concerned tracking operations. That was probably cloder to the line than I would normally venture, only because I didn't realize he had audio on his camera. Thankfully I was wise enough to leave out location and time details that probably kept it far enough from "the line" that I can sleep with both eyes closed.
Rip

No, I'm sure those processors aren't the extent of processing capability on a sub. I just had to smile when I read that. It just reminds me how far technology has come.
I think it would make far more sense to use an array of FPGA's to perform the signal processing. It would allow you to have a massive parallel DSP.

Rip, thanks for "Waking the line" on your explanations. It's nice to know our tax money goes towards really cool technology that we don't have the right to know about

Dr. Sid, I see you are working on an open-source cold war sub sim. How do you plan to model the sonar? Have you started on the work yet?

[Bubblehead Nuke]

I have chatted with Dr. Sid about that very thing. As long as the CONCEPTS are fundementaly correct, who cares about the exact numbers.

The devil is how to give someone an understanding of the engineering that goes into a sub without 'crossing' the line'.

To help with the sub handling models, I have researched and found a few choice books that are interesting reading to an aspiring sub sim designer.

[Dr.Sid]

Main difference compared to DW is the delays induced by finite sound speed will be correctly simulated, to such extent, that it alone will allow active sonar simulation.
Each sound will 'travel' and 'hit' other platforms in correct order, where it will get detected (for passive) or bounced (read new sound event will be generated) for active sonar. This is general mechanism how sound will get from source to listener.

This is actually what I'm working on in the moment.

As for transmission loss, layers, channels and so on, nothing like raytracing is possible because of huge amount of computing it needs, so it will be just lookup tables based on range, depth of listener, depth of target. However I plan to have these changing fluently with daytime and location. I'd also like to have let's say 3 frequency ranges so different frequencies can react differently on sound speed profile.

As for sound source, it's clear DW's 4 constant lines per platform is huge simplification, and I plan to have quite complex sound sources, since it's cheap. So there will be many components, each related to expected cause, and variable not only in amplitude, but in frequency too, where it should be. Propeler noise, flow noise, gear whine, pumps, steam noises, generators, you name it. And of course, correctly simulated transients, which will generaly be samples played (and heard on listener side) when some specific event happens (like torpedo tube opened, or coin dropped :rotfl.
This will make identification much harder and description of sub wont be 4 frequencies. Expect long process of guessing and ruling out. You should be able to tell 'this is ruskie sub' quite soon, while it might be hard to tell if it's delta III or delta IV. Anyway this rich possibilities will easily allow each hull to be slightly different.

As for listener side gear, it will just look slightly more complicated, there is nothing much wrong with it in DW, except it's simplistic at some details.

Of course there will also be MUCH more false contacts, and there will be better environment simulation.

[XabbaRus]

Sounds good Sid,

I have a week and a half off over Christmas....so I'll send you some more subs.

If you can let me know what happens with the surface models where they go weird on you I could try and mitigate it in the model before I send it.

I'd like to make a big push with this and get you some nice surface vessels.

[Dr.Sid]

Hopefully I get more time over Christmas so I'd like to find those 3ds bugs. Most probably I just ignore some sections which did not appear earlier.

[XabbaRus]

It's odd as they work in DW fine after being converted to J3D.

I'd have thought if there was a problem with the model DW would have shown it up.

[Dr.Sid]

There for sure is no 'problem' with those files. They just use some feature I don't support at the moment.

[Deamon]

Originally Posted by Dr.Sid

Main difference compared to DW is the delays induced by finite sound speed will be correctly simulated, to such extent, that it alone will allow active sonar simulation.
Each sound will 'travel' and 'hit' other platforms in correct order, where it will get detected (for passive) or bounced (read new sound event will be generated) for active sonar. This is general mechanism how sound will get from source to listener.

This is actually what I'm working on in the moment.

As for transmission loss, layers, channels and so on, nothing like raytracing is possible because of huge amount of computing it needs, so it will be just lookup tables based on range, depth of listener, depth of target. However I plan to have these changing fluently with daytime and location. I'd also like to have let's say 3 frequency ranges so different frequencies can react differently on sound speed profile.

As for sound source, it's clear DW's 4 constant lines per platform is huge simplification, and I plan to have quite complex sound sources, since it's cheap. So there will be many components, each related to expected cause, and variable not only in amplitude, but in frequency too, where it should be. Propeler noise, flow noise, gear whine, pumps, steam noises, generators, you name it. And of course, correctly simulated transients, which will generaly be samples played (and heard on listener side) when some specific event happens (like torpedo tube opened, or coin dropped :rotfl.
This will make identification much harder and description of sub wont be 4 frequencies. Expect long process of guessing and ruling out. You should be able to tell 'this is ruskie sub' quite soon, while it might be hard to tell if it's delta III or delta IV. Anyway this rich possibilities will easily allow each hull to be slightly different.

As for listener side gear, it will just look slightly more complicated, there is nothing much wrong with it in DW, except it's simplistic at some details.

Of course there will also be MUCH more false contacts, and there will be better environment simulation.

Good stuff Dr.Sid. I am curious how much of this stuff you will be able to pull out. I planed to do the same back in the days for my cold war project before I switched to WWI. But even for my WWI sim, I still want to do it.

[Dr.Sid]

That's actually why I like modern subs .. because you can play with sonar so much

[SeaQueen]

Originally Posted by Bubblehead Nuke

I have chatted with Dr. Sid about that very thing. As long as the CONCEPTS are fundementaly correct, who cares about the exact numbers.

That's so true. One of my pet peeves of naval simulations is how people obsess over all the techno-weenie details and end up missing the big picture. A good wargame should be about tactics and decisions. Details of specific numbers and knob twiddling should be secondary. They really only need to be in the ballpark because often the uncertainty on actual numbers is large and the impact of that uncertainty dwarfs the importance in terms of decisions than whether a given platform's source level at 138Hz is 120dB or 135dB.

[SeaQueen]

Dr. Sid, how do you plan to do better environment simulation and false contacts?

[Dr.Sid]

Honestly I don't know much yet. I did not discuss this much with anyone.

By environment I mean background noise. This seems to be covered quite well in Urick, and there is no technical problem (I know of).

As for false targets .. there should be more bio targets, rocks, ice peaks or wrecks, all with both passive (water flow and eddies for silent ones) and active, and magnetic and so on when we get there.

Also for active the bottom reflection should be made better I think, especially if it's rocky, there should be a chance to hide at the bottom (I guess).

Any comments are appreciated.