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6 hours ago, K^2 said:

It will probably be pretty obviously false, too diffuse and spread to be a single jammer on a single ship, but it won't indicate actual location of any particular ship in the network, either, until the sub gets really close.

While this would work for sonar guided ordnance, they would have enough of a fix to launch SSM's at the group.   The missiles would be assigned to home in on any radar targets, and so, yes, the missile catcher DD's would get hit first, sparing the carrier.  If there are enough subs in the area trying to attack a CVN group, you would end up with a rather depleted screen for the CVN, allowing for one of the subs to execute a final approach and attack via torpedo. 

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21 hours ago, K^2 said:

If you synchronize jammers, such as via radio, you can do something similar to a phased array to create completely false apparent location of the source.


Um, no.  Phased arrays create a beam through changing the phase of the emitted wave to create constructive/destructive interference - that's going to be practically impossible with emitters on seperate ships.  The distance are too great and the waveforms will have spread too widely.  Not to mention it requires foreknowledge of the bearing of the submarine so you can point the 'beam' in it's direction...  And unless the submarine is head on to the apparent direction of the beam, the towed array will clue the operator that the body arrays are being jammed or vice versa.  Plus modern sub sonars are really really good at looking down precise bearings - if the sub isn't looking down the bearing of your beam it'll likely not even notice it's there.  (Not to mention sonar analysis is just a bit more sophisticated than "hey, there's a noise over there".)

Even if this worked, it only does so if the submarine is far enough away that standard beamforming can't resolve individual ships...  Which means you're replacing the undifferentiated noise of the fleet with the undifferentiated noise of your jammer.  Still good enough to get a missile to the point where it's radar can take over.

That's why pretty much everyone has concentrated on decoys and passive masking systems (like pillenwefer), jammers don't actually work that well.  (Jamming works on radar (and is much more complicated than "make a lot of noise"), but passive sonar operates on different principles.)

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7 hours ago, DerekL1963 said:

Um, no.  Phased arrays create a beam through changing the phase of the emitted wave to create constructive/destructive interference - that's going to be practically impossible with emitters on seperate ships.  The distance are too great and the waveforms will have spread too widely.  Not to mention it requires foreknowledge of the bearing of the submarine so you can point the 'beam' in it's direction...

A phased array produces a hologram. It's omnidirectional. Just because typical usage is steerable beam, you shouldn't think that's the only thing you can do with it. And while angular resolution depends on how many grid points you have, a carrier group has enough coverage to create false source(s) of interference that do not correspond to locations of real ships. It's fairly straight forward to decompose the desired "image" seen from perspective of any sub into individual sources. If you don't understand how that works, I strongly encourage you to learn a bit of wave optics before you continue arguing the point. Especially, if you plan to start with "Um, no."

The objective isn't to mask your fleet from passive acoustics, so discussion of how involved it is is meaningless. We're talking about jamming. Throwing so much acoustic interference, that passive or active sonar are absolutely useless. You can have a human or a computer listening, and they'll get bugger all useful with absolutely any jamming method. Nor are we trying to hide a general location of a carrier group. If your navy doesn't know where enemy's carriers are at all times, you've already lost this war.

The only downside of jamming is giving away location of the jamming source, making the jammer itself an easy target. An array of jammers can produce false sources preventing this from happening without the enemy sub getting close enough to be immediately detected and engaged.

If torpedo aimed at a source of interference passes close enough to actual jammer ship by chance, yes, it will be able to hit it. If it doesn't, it will try to chase the false signal and most likely not hit anything. Alternatively, you can engage active sonar on torpedo early, and hope to pass close enough to something for jamming to not matter. Then you'll hit a random ship, but you give advanced warning to the fleet to use countermeasures.

To summarize, without jammers, sub can target specific ship, such as the carrier proper, on passives, and have torpedo engage active sonar when it's too late for target to engage countermeasures. With uncoordinated jammers, each jammer makes an excellent target and can be picked out one by one. With networked jammers, you lob a torpedo, and hope that it passes close enough to something to target it, which will be a random ship in the fleet. Does it provide perfect protection? No. It's a carrier group, and some of the ships are basically there to take hits, because a target that big and that important is not going to be hidden in the modern world. You job is to make hunter sub's job as tough as possible, to give your hunters an advantage, or to force enemy sub to reveal itself early. Networked jamming can potentially achieve all three, while not tying your hands on employing pretty much every other method as well, including decoys. It is a pure advantage over not doing this.

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On 10/7/2018 at 12:15 AM, DerekL1963 said:


Um, no.  Phased arrays create a beam through changing the phase of the emitted wave to create constructive/destructive interference - that's going to be practically impossible with emitters on seperate ships.  The distance are too great and the waveforms will have spread too widely.  Not to mention it requires foreknowledge of the bearing of the submarine so you can point the 'beam' in it's direction...  And unless the submarine is head on to the apparent direction of the beam, the towed array will clue the operator that the body arrays are being jammed or vice versa.  Plus modern sub sonars are really really good at looking down precise bearings - if the sub isn't looking down the bearing of your beam it'll likely not even notice it's there.  (Not to mention sonar analysis is just a bit more sophisticated than "hey, there's a noise over there".)

Even if this worked, it only does so if the submarine is far enough away that standard beamforming can't resolve individual ships...  Which means you're replacing the undifferentiated noise of the fleet with the undifferentiated noise of your jammer.  Still good enough to get a missile to the point where it's radar can take over.

That's why pretty much everyone has concentrated on decoys and passive masking systems (like pillenwefer), jammers don't actually work that well.  (Jamming works on radar (and is much more complicated than "make a lot of noise"), but passive sonar operates on different principles.)

Jamming works pretty well against active detection like radar and sonar who rely on an return signal. canceling out the signal would be very hard its easier just to distort it so it give false positives and distort your actual location. 
Yes you can turn off the radar and simply aim for the jamming that until its turned off to. 

Against passive detection its rarely work well it tend to make you more visible. 
One exception is against ambient, some use of bioluminence is for sea creatures to be brighter from below this makes them harder to spot as they block sunlight from below. Some WW2 planes also used this to reduce visibility. 

An phased array might work for sound but your rand of creating an mirage is probably limited. 

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17 hours ago, K^2 said:

I strongly encourage you to learn a bit of wave optics before you continue arguing the point.

I strongly encourage you to learn about submarines, sonar, and sonar employment before spouting off.  (I qualified Sonar Operator onboard SSBN 655 back in '85 - you?)
 

17 hours ago, K^2 said:

The objective isn't to mask your fleet from passive acoustics, so discussion of how involved it is is meaningless. We're talking about jamming. Throwing so much acoustic interference, that passive or active sonar are absolutely useless.


I understand that - which is why I patiently explained how passive sonar tracking and listening works so that you'd grasp that the problem is much more difficult than you assume.  You don't seem to realize that passive sonar is the primary tracking method, and that it works by "looking" (via beamforming) down a bearing.  If your source of interference (that hologram) isn't down that bearing...  passive sonar will ignore it.
 

17 hours ago, K^2 said:

 With networked jammers


You have a bunch of point sources of sound (fairly easily resolved from one another) emitting "jamming" noise and one hologram.  Your point sources will trivially be tracked by passive sonar and a torpedo wire guided into your carrier.

The only way to jam passive sonar is to create an overwhelming amount of background noise on the frequencies of interest - kind of like putting a spotlight behind a candle.  Point source emitters don't do that.  Holograms don't do that either.

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4 hours ago, magnemoe said:

Yes you can turn off the radar and simply aim for the jamming that until its turned off to. 

Most radar jamming systems I've seen seriously discussed don't offer a point source or bearing to the jamming source, they usually have overwhelmed the sensor so it is garbage from all directions, or at least a broad section of the sky.   Broad enough you can point in the general direction (like "It's coming from the West!"), but not enough to fire any ordnance with any hope of hitting the source. 

Now an anti-jamming weapons system is possible, for all the reasons in previous posts, but ECM (Electronic Counter Measure) warfare is a chess match.   Or better yet, a poker game.  Each side is very reluctant to reveal their capabilities, and so designing a SAM to counter airborne ECM is doable, but very problematic.  They would have to get a good set of data on the types of ECM one side is using, and then design a weapons to counter that.  The ECM side of it will quickly learn they are being defeated, and make changes to their software, which is 'relatively simple' to do, and they already have alternate software designed for this purpose (probably back at the system contractors, but it wouldn't take much for them to change the software).  A weapons system would have many more components to alter to match the new system they are encountering.  The missiles themselves would require new seeker heads and software, so instead of just changing the software on a few planes, hundreds of already made missiles would need updated. 

They do actively change up the tracking radars to help counter ECMs, as needed.  But ECM operators are very reluctant to use their systems until it's absolutely necessary, giving the other side as little info as possible, as the targets they are jamming are usually destroyed shortly there after.    It is very rare for an ECM system to be used against a target they don't intend to destroy.  That's why in most of the major conflicts of the past 60 years where one super power is actively engaged, and the other is officially not (Both Afghanistans, both Iraq wars, Syria, Vietnam, Balkans, you name it), the non participant has technicians and observers in the field to gather as much data as they can to upgrade their own systems.   With the lack of data on ECM systems, it is hard to design and deploy a weapons system to defeat them within the time frame of most major actions.    Doable, but hard. 

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2 hours ago, Gargamel said:

Most radar jamming systems I've seen seriously discussed don't offer a point source or bearing to the jamming source, they usually have overwhelmed the sensor so it is garbage from all directions, or at least a broad section of the sky.   Broad enough you can point in the general direction (like "It's coming from the West!"), but not enough to fire any ordnance with any hope of hitting the source. 

That heavily depends on the type of jamming and it's sophistication - to the point where home-on-jam is built into many xAM's that use active radar homing.  It's better than nothing.

https://fas.org/man/dod-101/navy/docs/fun/part11.htm

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7 hours ago, DerekL1963 said:

That heavily depends on the type of jamming and it's sophistication...

The American Armed Forces Radio has a station in Puerto Rico.  I spent a couple of months down there during the winter of 1987.  I seem to recall the Cubans simply broadcasted noise at the same frequency as the AAFR.  Or maybe it was the Americans broadcasting noise over the Cuban radio station (or both even).  If you listened carefully you could hear the radio station but the random whirrs, screeches and growls gave you a headache rather quickly!      

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On 10/5/2018 at 9:03 PM, Gargamel said:

No, that's a decoy.   A decoy gives a false positive return on a sensor.   The operator believes the sensor is operating properly, and may be misled to believe there are more targets than there actually are.   Jamming constitutes making a sensor useless.    The operator is fully aware that they are being actively jammed, and cannot trust most of the info they are receiving. 

Imagine you are standing in the middle of an arena full of silent people.   One singer is singing loudly, and is located somewhere in the crowd.   Your job is to locate that singer.   Now a couple of the people are holding up speakers that are playing a recording of the singer.  You now have a couple false targets to investigate.  Those are decoys.  You can fully use your ears for other uses, such as talking to and listening to other people, and using triangulation to home in on the multiple sources of the singing. 

Now the other 40,000 people in the stadium start screaming as loud as they can.   You can not even hear your self think.  This is jamming.   Not only can you not hear the singer, but you can't even hear somebody standing right next to you. 

 

The problem with sonar jamming is that creates a point source.  You have no idea whats over there, but you know something noisy as heck is in that direction.    The only way to really jam a passive sonar system is to have multiple jamming sources surrounding your target.   This is very impractical, as in peace time, it would be merely annoying and wasteful, but in wartime, you already know where your target is, so just drop a few torpedoes on them. 

 

EDIT: Dangit... can't quote in an edit.... see below:

 

 

Decoy, jamming, semantics ;)

 

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20 hours ago, DerekL1963 said:

I understand that - which is why I patiently explained how passive sonar tracking and listening works so that you'd grasp that the problem is much more difficult than you assume.  You don't seem to realize that passive sonar is the primary tracking method, and that it works by "looking" (via beamforming) down a bearing.  If your source of interference (that hologram) isn't down that bearing...  passive sonar will ignore it.

It will not. If you learn the physics of how it "looks" in a specific direction, you will know that it picks up the waves coming down from all directions, but only ones that come from specific bearing interfere constructively, producing signal only from that direction. This is true if your sources are not coherent, which is the case for any natural source or uncoordinated jammers.

If you have multiple synchronized, coherent sources, this no longer works. And I can produce a false source at a bearing I chose relative to your passive sonar, at location where no real source exists. Again, wave optics.

My background is ten years of quantum physics. That is explicitly physics and mathematics behind wave propagation. I don't know exact engineering that goes into acoustic pickups on a sub, because I'm not a naval engineer. I certainly don't know anything about operation procedures. But I don't need to. I know how to construct an incoming sound wave that is indistinguishable from the wave reaching the sonar from a specified direction where no real source is located. And if the incoming waveform is identical there are no means to distinguish the source. You cannot get information that's not there, no matter how sophisticated the hardware. It's not magic, after all.

I can write out the equations, including a mathematical model of a perfect passive sonar, that has ability to select sources by bearing. And I can show that even this perfect, ideal, mathematically precise sonar will be fooled, let alone any actual physical implementation that will do worse. I just don't know if it makes any sense for me to write out equations that are going to involve Fourier transforms and convolutions, or if it's going to bounce right off.

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44 minutes ago, K^2 said:

It will not. If you learn the physics of how it "looks" in a specific direction, you will know that it picks up the waves coming down from all directions, but only ones that come from specific bearing interfere constructively, producing signal only from that direction.


It's a lot more complicated than that, because you're missing the intervening signal processing steps - particularly the delay lines (done via software nowadays) that actually produce the beam.  (And there's also post processing of the resulting beam, and that's all I'm gonna say about that.  I don't care for summers in Kansas.)

 

50 minutes ago, K^2 said:

And I can produce a false source at a bearing I chose relative to your passive sonar, at location where no real source exists.


I never said you couldn't - I said passive sonar will ignore a source (false or real) that's not on the bearing it's looking down.  If the sonar is looking at 45 degrees and your decoy target isn't at 45 degrees...  it won't be heard until they look down the bearing your decoy is down.  Then...  well, unless you can create an accurate and complex decoy signal that sounds like a ship (a very tall order and there's more to it than you think), the operator will mark that sound source as a decoy and ignore it from then on.  (This is old hat, we could do it in the 80's with 70's (and older) gear.)

Even if you can match a ship's complete signature, you've added (at great expense and difficulty) what, a single decoy to an entire formation?  (The precise directional emitters you'll need aren't cheap to build, install, or maintain.)

And meanwhile, the active emitters are making it easier for the submarine to track the actual targets...

And I haven't even gotten into the problem of resolving the relative positions of the emitters and predicting relative motions with sufficient precision to enable the creation of the decoy in the first place.  (Ships underway are moving in three dimensions and changing attitude about all axes - they aren't theoretical equations.)

(And I'll note in passing that you've moved the goalposts from jamming to creating a decoy...)
 

1 hour ago, K^2 said:

I don't know exact engineering that goes into acoustic pickups on a sub, because I'm not a naval engineer. I certainly don't know anything about operation procedures. But I don't need to.


I see.  You know you don't know stuff, and you dismiss the stuff you don't know as irrelevant.  Whatever.

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1 minute ago, DerekL1963 said:

It's a lot more complicated than that, because you're missing the intervening signal processing steps - particularly the delay lines (done via software nowadays) that actually produce the beam.  (And there's also post processing of the resulting beam, and that's all I'm gonna say about that.  I don't care for summers in Kansas.)

Yeah, and delay lines are precisely what allowed you to select a phase adjustment to signal received at each pickup, which lets you exclude everything but the beam you're interested in. It's like having a lens in front of the light detector, and rather than moving light detector, you change thickness of the lens to look in different directions. Interferometer telescopes work in exactly the same way, and they aren't classified. The advantage of working with sound or radio frequencies is that you can throw away the delay lines, record the signal with phase information intact, and then do any phase shifts you need in software. And that really gets us back to a phased array, with the difference that you need to correct for sonar dome shape, while giving you the signal strength of the full dome, rather than that of the array.

I know you're probably read-in, so you can't talk about details regardless, but it's the kind of secret that isn't. At least, in broad strokes. I'm sure there are plenty of reasons to keep the details classified.

1 minute ago, DerekL1963 said:

I never said you couldn't - I said passive sonar will ignore a source (false or real) that's not on the bearing it's looking down.

I see where you're going with this, but still no. If you tune this to a bearing of a true source, you won't get any signal that's distinct from background noise, because you'll be getting noise from all the other sources hitting your pickups at just the right timings to travel down these delay lines and cancel out the actual signal from the source you're staring at.

I could probably come up with a way to punch through this if we were looking for something very specific, like engine noise, while several sources produce fake engine noise, trying to project it to a false location. Alternatively, if there were at least a few subs that shared their raw acoustics data in real time, you could probably resolve true sources. But if we're staring at a bunch of jammers, your signal processing is already busy filtering out the noise, so you can try and locate sources of jamming signal. So the only place where the sonar's going to give you a signal that's distinct from background noise is if your beam is pointing at the false source. Looking at a true source will give you the same kind of noise as pointing in any other direction.

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3 hours ago, K^2 said:

I see where you're going with this, but still no. If you tune this to a bearing of a true source, you won't get any signal that's distinct from background noise, because you'll be getting noise from all the other sources hitting your pickups at just the right timings to travel down these delay lines and cancel out the actual signal from the source you're staring at.


o.0  That sentence makes no sense whatsoever - if you tune what to the bearing of a true source?  The passive sonar?  You're saying you can completely blind a passive sonar regardless of the bearing it's focused on?  Not buying it.  That requires precise knowledge of the submarine's position and what the submarine should be hearing and how it's processed in order to produce the required precise waveforms (at the precise time) to cancel it.

And you're going to do this in an environment where the emitters are constantly moving in relationship to each other and to the submarine.

Not happening in the real world no matter what your abstract equations say is possible.  (That you ignored my comments about mechanizing the system is telling.) 

 

4 hours ago, K^2 said:

I could probably come up with a way to punch through this if we were looking for something very specific, like engine noise


I already told you we're looking for specific things in the sound.  You're not even reading what I wrote (for at least the second time).

I'm done conversing with you on this topic.  I'm trying to learn what I don't know, but you've already dismissed the things you don't know as irrelevant.

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17 hours ago, DerekL1963 said:

If the sonar is looking at 45 degrees and your decoy target isn't at 45 degrees...  it won't be heard until they look down the bearing your decoy is down. 

This implies that the SONAR operator is a critical link in the passive SONAR operation (I'll buy that).  Otherwise any Nvidia Titan (put in a suitable rugged box for MIL-STD qualification) can pretty much compute every single direction effectively at once.  There are only so many operations you can do on the limited numbers of audio samples you can get (no, it still doesn't matter how many microphones you have, you aren't going to get much beyond 1Mb/s out of any one microphone, and GPUs do TFLOPS).

On 10/5/2018 at 5:23 PM, Gargamel said:

@wumpus "But that "original signal" is still buried underneath all  that noise.  Too constant, and it becomes easier to subtract out the jamming noise as the jamming noise and target sound change relative position.  Too (pseudo) random a jamming noise, and you can average the signal out over time and hear the target signal."

And yeah, that takes a lot of time, but that's what subs are really good at, slowly tracking targets over time.   Given various environmental conditions, they might be able to track a target hundreds of miles away, and over the time it takes to get close enough to shoot, they can eventually filter out the noise.  

On second thought what you do is create an array of FFT data, each "aging out" after being repeated for some prime number (so everything doesn't change all at once).  Add up all the numbers from each array and the "too random/too constant" problem goes away.

13 hours ago, DerekL1963 said:

o.0  That sentence makes no sense whatsoever - if you tune what to the bearing of a true source?  The passive sonar?  You're saying you can completely blind a passive sonar regardless of the bearing it's focused on?  Not buying it.  That requires precise knowledge of the submarine's position and what the submarine should be hearing and how it's processed in order to produce the required precise waveforms (at the precise time) to cancel it.


 Never mind how impossible it is to know his exact location, think about what it means to jam it (in such a way to create a false image).  In peacetime you are effectively stating "I know exactly where your subs are (to within millimeters, and speed to millimeters per second)" (think how much damage the Walker family did when they told the USSR exactly this).  In wartime you simply hit them with a torpedo, no jamming required.  There's simply no reason to do this type of thing.

I don't think the US Navy ships running aground have much to do with SONAR (or even GPS meddling, although that likely has been used by Iran to capture a drone).  More likely Fat Leonard has screwed up the Pacific Naval officer corps far worse than publicly known.  Exact SONAR fakes are basically impossible (RADAR probably works, especially for airborne RADARs.  I'd expect ground based stuff often has more receiving antennas than you expect).

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17 hours ago, DerekL1963 said:

You're saying you can completely blind a passive sonar regardless of the bearing it's focused on?  Not buying it.  That requires precise knowledge of the submarine's position and what the submarine should be hearing and how it's processed in order to produce the required precise waveforms (at the precise time) to cancel it.
 

That's like saying, I need to know where the eyes are going to be located to produce holographic image in front of the screen, hovering where no physical object exists. Yet a hologram certainly works, I hope you're not going to deny it. A phased array produces a signal that matches any desired pattern of waves, including these that match perfectly with any non-existent source within the area spanned by array, to within error permitted by density of an array. A carrier group has sufficient density to fool a single sub, regardless of where it is locating, to perceive false sources only and be blind to true sources of interference. This is fairly heavy math on top of very basic wave physics, and this has been known for well over a hundred years.

I'm telling you that I can reproduce the exact sound that would be coming from an object at desired location, projected in all directions, with nothing at that location. This is tried and tested tech. You are telling me it's not good enough, because you believe in some magical ability of the sonar to know that there is nothing there, despite the actual sound wave reaching it being absolutely identical.

17 hours ago, DerekL1963 said:

I already told you we're looking for specific things in the sound.  You're not even reading what I wrote (for at least the second time).

I have read it. I'm sorry if my response wasn't sufficiently clear. We're talking about two completely different scenarios here.

1) I want to mask the fleet, hiding it entirely. I employ noise-canceling with an active array. You want to cut through it. You're looking for very specific, repetitive sound of an engine, impeller, or any other periodic noise, really, that you can lock onto. Given a slow scan of the beam, you'll eventually succeed, no matter how good my noise-canceling is. This is what I mean when you're looking for specific target in otherwise quiet background.

2) I want to mask locations of individual ships within a group, without giving you anything concrete to lock onto, under assumptions that you already know where the group is overall. I deploy jammers instead of noise-canceling, and network them to produce patches of high intensity in areas where no ship is located. You do not have a pattern to lock onto, because noise is inherently non-periodic. Any known sources of sounds coming from ships are greatly overwhelmed by omnidirectional background of noise. And yes, even if you have a beam, you will pick up a lot of noise from all directions when jammers are used. I hope you at least know that much. The reason you can still normally lock onto a jammer is because the beam will generally cut back some of the noise from directions other than directly from jammer. So while being jammed, what a sonar sees is noise and patches of more noise. Hence use of an array of jammers to create false sources of high intensity. So as you scan your beam, you'll see noise everywhere, with patches of it, that you believe to be jammers, at some locations within the group. These, however, do not correspond to any physical target. At this point you've already exhausted ability to steer the beam and to filter the signal, and they produce absolutely nothing. Short of employing active sonar, you're not going to get anything useful in this scenario.

17 hours ago, DerekL1963 said:

I'm trying to learn what I don't know, but you've already dismissed the things you don't know as irrelevant.

You don't understand the things you are claiming are relevant. I'm sure you know the specs. But if you don't understand how a phased array produces a signal, what kind of signal it can produce, and how specifically any number of beams can be produced from a single array starting at any point within the array, then I'm sorry to say that you don't understand how the sonar works either. Because a modern sonar is a phased array attached to a dome and any number of additional resonators with lots of additional processing on top. I don't know the specs of the dome. I don't know the arrangement of pickups or their relevant resonances. I don't know the software suit that goes on top of it. But none of that changes how it works. Only the quality of the signal you get and how narrow a beam you could make. And I'm telling you that an ideal device, with perfect reception, and beam as tight as physical dimensions of the dome can possibly allow, is insufficient to cut through this. So yes, that makes any technical details of an actual physical sonar, which will perform worse than this idealized sonar, absolutely irrelevant. It can't perform better because math. And if it performs worse, my argument is only stronger.

If you feel that's good enough reason for you to smugly dismiss the whole argument, I won't stop you.

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18 hours ago, DerekL1963 said:

And you're going to do this in an environment where the emitters are constantly moving in relationship to each other and to the submarine.

Not to mention the environment itself, where due to salinity and temperature changes, acoustics can do different things at different times. 

 

23 minutes ago, K^2 said:

2) I want to mask locations of individual ships within a group, without giving you anything concrete to lock onto, under assumptions that you already know where the group is overall.  [SNIP]

Logistics logistics logistics.    This is assuming a perfect world.

Subs are made to hide.   They are, for all practical purposes, invisible.     Deploying such a system would require knowledge of the subs location.   Even if you don't need the exact location, you need to know where they are generally.    If you know the location of sub, it is practically trivial to kill it.   ASW Helicopters would be deployed and they would drop torpedoes onto it.  At this point, even if they don't get the kill, they can harass it enough so it has to run away.   

Data on various ships noises are already known.  They can be tracked upon leaving port, or even just crossing over a SOSUS line.   In peace time, there would be little advantage to deploying such a jamming system, even if it is possible (I'm not arguing yes/no here).   You would be giving up data on your jamming capabilities, and then the sub would know they were found, and just pop up to scope depth and track the group that way.    And if they can pop up to scope depth, they can accurately fire a torpedo, the same way they've been doing since WWI, with math. 

But once a sub has been located, it's pretty much a sitting duck.  Helicopters and ASW Aircraft are significantly faster than a sub running flat out, and a torpedo is roughly twice as fast.   They only thing deploying a jamming system does is give away the location of the group to every sub within a couple hundred miles.   

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24 minutes ago, Gargamel said:

Subs are made to hide.   They are, for all practical purposes, invisible.     Deploying such a system would require knowledge of the subs location.   Even if you don't need the exact location, you need to know where they are generally.


That's a huge problem - because your alternative is to pump enormous quantities of energy into the water to produce an omnidirectional blanket through hundreds or thousands of square miles of ocean around your fleet in order to ensure the sub is inside the blanket.  The submarine won't need sonar to find the fleet, they won't even need to put a glass against the hull...  In fact, the crew will probably require hearing protection.
 

31 minutes ago, Gargamel said:

And if they can pop up to scope depth, they can accurately fire a torpedo, the same way they've been doing since WWI, with math. 


Fun fact, TMA (Target Motion Analysis) doesn't care about the source of the data - visual via the periscope, electronically via the radar, or aural data via the sonar...  If you can get a decently clean bearing, and make reasonable guesses as to range, speed, and course...  You can generate a trial solution and then refine it by comparing the calculated bearing to the actual bearing.  (The computing devices the USN deployed in WWII to mechanize this was the sub force's real secret weapon.)

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9 hours ago, Gargamel said:

Subs are made to hide.  

This. There is a lot of guesswork being passed off as military fact up in here. A lot of operational assumptions being made on individual technical facts, without any consideration to physical/military reality.

 

Edited by p1t1o
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Now, while the argument about jamming sonar tracking systems in reality is pretty much settled here IMO, there is the question of jamming a weapon.

Torpedoes generally have two modes of guidance.  Wired and unwired.   In the wired mode, they are literally unspooling a long wire back to the sub.  This wire can be many km's long.  During that time, the weapons officer on the sub, with data from the sonar operators, steers and controls the torpedo.   The wire leads back into the torpedo tubes, so while they are driving the fish, they cannot reload that tube, as the outer doors have to remain open.    But once they cut the wire, the doors can be closed and the tubes reloaded. 

Once the wire is cut, the fish usually goes into active acquisition.  It starts using it's own active sonar system to locate and hit a target.   These systems are far less complex than what is found on a sub, and are completely automated. 

Since the target vessel would now be able to hear the exact sonar pings the torpedo is emitting, would it be possible to emit a "white noise" or wave cancelling or whatever you want to call it, to negate the pings from the torpedo?   This would fall more under 'active stealth' than jamming, but... .   As the emitter would cancel out the sound waves of the ping, could we keep the ship from generating a return to the fish? 

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2 hours ago, Gargamel said:

Since the target vessel would now be able to hear the exact sonar pings the torpedo is emitting, would it be possible to emit a "white noise" or wave cancelling or whatever you want to call it, to negate the pings from the torpedo?   This would fall more under 'active stealth' than jamming, but... .   As the emitter would cancel out the sound waves of the ping, could we keep the ship from generating a return to the fish? 


In theory, yes...  But isn't going to be simple.

Cancelling requires precise, and ever changing timing as the intercept geometry changes.  And it requires precise (or fairly precise) replication of the signal.  A fairly tricky processing problem.

It also depends on how sophisticated the signal processing gear on the torpedo is.  Modern electronics can pack a lot of power in not very much space.  The MK48 MOD7 CBASS has a pretty sophisticated sonar and specific anti-countermeasure features.  (The MOD7 came out long after I got out, I'm just relaying what's publicly known.)

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I want low-tech options to store large amounts of energy in a way which can be released rapidly and recharged.

By low-tech, I mean: No electrics, no composite flywheels, and absolutely no atomics or—kraken forbid—antimatter. Relatively modern metallurgy, without the exotic stuff like amorphous metals, not much in the way of polymers or composites. Detailed understanding of oxidation, though I would prefer a non-chemical solution.

By large amounts, I mean: Somewhere on the order of megajoules per kilogram, and megajoules per liter.

By rapid release, I mean: Somewhere on the order of megawatts to gigawatts, or less than a tenth of a second, whichever is a smaller amount of power.

By recharged, I mean: Reliant upon an easily-reversible process. Only certain chemical processes are applicable, and I'd prefer to find a more interesting solution than a hydrogen fuel cell. Something like a flywheel qualifies.

Outside the scope of the question are: Actual retrieval/regeneration of the energy; what will be done with the energy; acquisition of the energy in the first place.

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21 minutes ago, 0111narwhalz said:

I want low-tech options to store large amounts of energy in a way which can be released rapidly and recharged.

By low-tech, I mean: No electrics, no composite flywheels, and absolutely no atomics or—kraken forbid—antimatter. Relatively modern metallurgy, without the exotic stuff like amorphous metals, not much in the way of polymers or composites. Detailed understanding of oxidation, though I would prefer a non-chemical solution.

Welcome Sysyphus, the inventor and famous patron of the gravitational energetics.

Spoiler

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and his little friends inspiring the human engineers.

Spoiler

images?q=tbn:ANd9GcR510grUZ7ygqs5OSwnTiFjpg

 

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11 hours ago, 0111narwhalz said:

I want low-tech options to store large amounts of energy in a way which can be released rapidly and recharged.

You and the rest of the universe. 

11 hours ago, 0111narwhalz said:

no composite flywheels

It really doesn't get much more low tech than a fly wheel......

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11 hours ago, 0111narwhalz said:

I want low-tech options to store large amounts of energy in a way which can be released rapidly and recharged.

By low-tech, I mean: No electrics, no composite flywheels, and absolutely no atomics or—kraken forbid—antimatter. Relatively modern metallurgy, without the exotic stuff like amorphous metals, not much in the way of polymers or composites. Detailed understanding of oxidation, though I would prefer a non-chemical solution.

By large amounts, I mean: Somewhere on the order of megajoules per kilogram, and megajoules per liter.

By rapid release, I mean: Somewhere on the order of megawatts to gigawatts, or less than a tenth of a second, whichever is a smaller amount of power.

By recharged, I mean: Reliant upon an easily-reversible process. Only certain chemical processes are applicable, and I'd prefer to find a more interesting solution than a hydrogen fuel cell. Something like a flywheel qualifies.

Outside the scope of the question are: Actual retrieval/regeneration of the energy; what will be done with the energy; acquisition of the energy in the first place.

First idea was water yes you need an good fall height but if you have an good height difference I would go for that hard to get all the energy out at once unless you have some serious engineering.

Compressed air should work well, bonus in energy release, you could make an compressed air cannon who would work as well as an black-powder one so both power density and high peak power is satisfied. 
Buildable with 19th century tech, you could both power an turbine or use it for pneumatic. 

Why do you want an very high energy release? Ask because various systems has strengths and weaknesses. 

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