XB-70Um…intermittent funding, the drawdown in engineers (which might bounce back), trouble acquiring needed technology…
Granted, not every article paints an accurate picture. But if this one does, and it doesn’t straighten out quick, then it’s going to be a long road.
XB-70Sounds like the program is a complete mess. No way is 2026 realistic if that is the state of the program. Not even for a prototype flight.
XB-70[USER=”71228″]garryA[/USER]
Deceptive jamming is not the same as noise jamming in the sense that they attempt to inject false information that can be interpreted as real return instead of only simply blank out the real return like noise jamming.
Yes, but that is like comparing an apple to an apple (which may have different sizes and hues but are both apples). With either approach, the aircraft scanning with radar will get a return from the aircraft employing jamming. With active cancellation there will be no return. (Now we are talking apples to oranges!)
1) That correct, but while the signal the threat radar received will be weaker, the pulse length is the same.
But what I’m getting at is that at a great enough distance, it may not matter. Every electronic device has a natural noise floor, and a signal has to be above that floor to be registered. The Rafale can register the pulses from a targeting radar at a greater distance than that from which the targeting aircraft can get a proper pulse – because it has to attenuate by 1/d^2 again. (The converse is also true though, and the capabilities of both aircraft’s RWRs would have to be assessed here. My point was only that it may not matter!) And, again, if it does show up for a mere display frame or two it likely won’t matter then either.
2) That assumption is only correct, if the radar use a constant frequency/ PRF rate, because after the initial delay, your jammer can adjust to completely silent enemy radar (since you now know exact frequency and phase of reflected signal in the future). However, if adversary radar constantly frequency hopping and jitters their PRF randomly, then there will be a part of each individual pulse (or sub-pulse in case of pulse compression) that you can’t “cancel”…
Nope! Rather your counter argument is only true if the French tried a strictly real time approach. If you look back at my older posts you will see that I have said a few times that I do not believe that the French technology would work against an unknown radar system. This is because I do not believe that they are using a fully real time approach, and I don’t believe they can.
US stealth technology is strictly a real time approach. It is based off of shaping and absorbent properties of materials. The RF energy emitted by a radar system is a form of electromagnetic energy. It has an electric field component and a magnetic field component. With conductive absorbers the electric part of the field interacts with the electric field within the absorber material, altering it, which imparts kinetic energy to the conductive particles which is then dissipated as heat. With magnetic absorbers it is the same thing, only interactions between the magnetic fields. Since it is electric field-electric field or magnetic field-magnetic field interactions they happen at the speed of light and so are instantaneous – real time. And there is a particular type of absorber that the French are trying to mimic – one which reflects the non-absorbed portion with a 180 degrees phase shift.
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But the French have a problem since they are trying to use *electronic warfare*. Electrons in a conductor travel very fast, but they do not travel at the speed of light. Thus, the electronic processing is not instantaneous. And thus you cannot use a full real time approach to achieve full cancellation (you would always be reacting to events with lag). But engineers know how to cheat!! A phase shift is the same thing as a time delay. To cancel the reflected signal all you have to do is calculate a good time to start emitting the exact same signal! The time you choose will be such that the two signals (reflected and yours) are 180 degrees out of phase and thus cancel one another. So their system simply needs to first analyze the incident radar signal and determine what it is, pull characteristics of it out of memory, and then do some final processing to account for attenuation of the reflected wave, doppler effect and such (the time needed for these calculations are also precalculated and used for the final phase shift). Then you start transmitting. A proper radar return is sent back while the upfront analysis is being done but after that – practically nothing. And if it shows up for a frame or two it won’t really matter.
So there are some differences between US and French technologies.
1) Theirs is only as good as the intelligence put into the mission file. If you guess wrong on what threats you might find then they might not have the proper characteristics stored in memory.
2) Electronics still takes time to process information. If you light up a US stealth aircraft with 20 radars it doesn’t matter. The shaping and absorbers instantaneously reacts with all of them. The French system will have to process them a little at a time and will (at some point) be overwhelmed.
3) US tech is fine against unknown radars; the French tech isn’t.
BTW, this actually isn’t a revolutionary thing. If you want to look into an application of where a hybrid approach like this is used (and has been for a long time), read about 3D graphics. You have the problem of determining how light emitted from various sources interacts with the environment and finally registers in your eye. Some of this you calculate real time with ray tracing. Some of this you precalculate – before runtime – and you simply fetch the resulting lightmaps, specular maps, etc. from memory as needed to touch up brightness, glossiness and such where you need it. You don’t have infinite processing speed nor infinite memory – and so you find a finite combination of both that works!
You might think, this part is small and negligible but
leading-edge-tracking…
After the upfront work is done there won’t be any leading edges to trigger on.
Anyways, this has gotten OT for the Rafale thread and so I am leaving it. I don’t mind discussing it further on a dedicated thread.
XB-70Tomcat is referring to self protection jamming (normally deceptive jamming) which is quite different from support jamming (normally noise jamming).
[USER=”71228″]garryA[/USER] – Well, I looked into several of these and they aren’t really different at all.
They even say as much. “Any practical jammer must radiate sufficient power to over-ride, or pre-dominate in its effect over, the natural target skin echo.” So, these methods still use the same principle where a larger ‘noise’ signal outweighs and masks the true signal (which is still there). That’s why they call it jamming. (It does appear to be more localized over geographical area but no other difference.)
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.507.516&rep=rep1&type=pdf
https://apps.dtic.mil/dtic/tr/fulltext/u2/336943.pdf
…because there will be a delay from when adversary signal hit your airframe and when the jammer can produce a 180 degree out of phase wave, in other words, there is a part of the pulse that you can’t cancel.
Yes and no. Sure, it ain’t like US stealth technology. The technology they have appears to require the characteristics of the ‘threat’ radar to be known to the system (and it can probably only work against one or two at a time). It also depends on how well they have characterized the rafale from all aspects with all loadout configurations (and certainly that will sometimes be just a rough estimate). But the time to reproduce shouldn’t usually be critical. When it first detects a scan it will need some time to first analyze the threat radar before it can send out a mimicked signal 180 degrees out of phase. But there are two points you need to consider. 1) The power from a radar signal attenuates under a 1/(d^2) characteristic – both ways. So the Rafale can capture a signal at a threat power level before that threat can capture the (even further attenuated) reflected signal. Usually. 2) Humans need a lot of time (in comparison with electronics) to capture and process information. A cockpit display refreshes at say 60fps (or 1 frame every 0.0167 seconds). If it takes the system 0.25-.03 seconds to capture pulses and process the info then it still might only show up on one frame. That’s not enough for a person to notice; it would be there and gone in the blink of an eye. And that’s assuming the radar’s processing doesn’t write it off as a noise spike and discard the info.
XB-70[USER=”39911″]TomcatViP[/USER] – What do you mean by self-jamming? You would never want to degrade your own sensory capability. Dassault’s technology is a form of electronic warfare, yes, but it is not jamming. Jamming is about degrading SNR with broad area noise. That’s been the case ever since the RAF first started dropping chaff over Germany back in WWII – resulting in the valid radar signals from their bombers being lost and hidden in the noise and so the German guns couldn’t locate them. Active cancellation takes a different and more precise approach. The addition of two sinusoidal signals of the same frequency and amplitude, but 180 degrees out of phase is always zero – for all time. So, when the Rafale uses it, the sum of the enemy’s reflected radar signal and its own active cancellation signal is zero – as if there were no radar return and the aircraft had a RCS of zero. (Now there is always some time jitter/phase noise in both signals so it will never be exactly zero – but close.) It only covers yourself. EW platforms traditionally cover others and so do not use this approach. But any EW platform with the correct precision in amplitude and phase (and also had a comprehensive RCS database to work with) could do it. It’s not magic.
XB-70Thanks for the link, halloweene! OK, it looks like the processors have been (certainly) upgraded to 733MHz PowerPCs, and it suggests that they are currently 1GHz+. But nothing was mentioned about replacing that STANAG 3910 bus. I’ve heard the F-35 is also PowerPC based (an architecture that is known to be particularly environmentally hardened and so has been used on Mars rovers and such) but I’ve never found anything definite. The increase in processing power would suggest they replaced the STANAG 3910 bus but it isn’t certain. Replacing it would be a far greater task than swapping out a device (processor or sensor) on that bus.
[USER=”77048″]St. John[/USER] – You’ve got to do that anyways to be effective. Although you want to degrade your adversary’s use of the spectrum while jamming you do not want to degrade your own use of it. So you have to know a bit about your adversary’s capabilities. The X-band, for instance, is defined as 8-12GHz. An X-band radar though only outputs a 100MHz or so pulse which sweeps/hops across that 8-12GHz over a period of time (microseconds). So you can jam by outputting broadband noise across 8-12 GHz which will do very well at keeping your adversary from using the X-band but it also does just as well at keeping your own forces from using it. Or you can try to follow your adversary’s transmitter, and just corrupt what it is scanning at. (This will still cause some collateral damage for your own forces, but far, far less.)
The differences with Dassault’s active cancellation and traditional jamming is 1) precision. For jamming, you really only want to follow frequency very well. Phase is not so important, and power you want to be high. For active cancellation, you do want to be exactly 180 degrees out of phase and you want your power to be precisely equal to the power of the reflected wave from your aircraft. Now, if a particular jamming system has the precision for each property then it could try to use active cancellation. But 2) the mission requirements come into play. A USN Growler is often the support aircraft on strike missions. It is just there to degrade hostile’s use of the spectrum with EW so that other assets can deploy weapons safely. If you need to cover for someone else then you aren’t going to try active cancellation. That only works for covering your own tail. Usually jamming assets are there to cover others!
XB-70I thought most modern jamming systems did that.
Nope. Most jammers are used for denying/degrading an adversary’s use of parts of the RF spectrum over large areas. So they are geared for transmitting at high power levels over a wide frequency band (or a rapidly shifting one). They also attempt to create false targets through the exploitation of vulnerable sidelobes. They try to cover and shield several assets over a wide area. Dassault’s “active stealth” is an attempt to shield just the fighter.
XB-70The little loop on the LM doc shows exactly that. There are no IR or Radar feed in teh fusion process.
It’s a closed loop and so it actually does show that. The Lockmart slide is just a generalization of previous sensor fusion schemes anyways.
Here’s a link with some detailed info on the Rafale’s microelectronics hardware. http://adsabs.harvard.edu/full/1996ESASP.375..111N
Basic capabilities:
2 SPARC processors @ 33MHz
STANAG 3910 avionics standard (just like Typhoon)
Max bus bandwidth – 20Mbit/s
Coded in Ada
It’s built for devices to talk together – they simply have to comply with STANAG 3910 (or MIL-STD-1553). I really don’t know what it is that you read that’s got you thinking otherwise.
2nd the lack of a coherent planing in system upgrade that led all sensor (apart from from the SPECTRA suite) to be removed/replaced.
STANAG 3910 is plug and play. You can replace components on that bus just like how you can swap out devices plugged in with Ethernet or USB. You just have to obey the transfer protocol and physical layer requirements. The French would have had to have been grossly incompetent to mess that up. What did you read that makes you think this?
XB-70
Is there a difference between active stealth and ordinary suppression jamming?
Yes there is. You have to know a lot more about the capabilities of the threat transmitter to use “active stealth” because you have to transmit your own signal at exactly the same frequency and 180 degrees out of phase. Your transmission power also has to be properly scaled to match the predicted reflected signal from your own aircraft. You don’t have to be that precise with normal suppression.
XB-70Sensor fusion is about maximizing situational awareness. Part of that is de-cluttering. You don’t want the pilot to be confused. But it goes farther than that because, with sensor fusion, your various sensors can talk to one another to coordinate so as to get the pilot more information. Please allow me to pimp some of Lockmart’s marketing. (Since a picture is worth a thousand words)
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As can be seen, you have a process loop. The various sensor data is analyzed and correctly correlated, and then the best fit solution is fed to the pilot. But the pilot is also able to feed that best fit information back. If the best information is being held on radar, but the pilot needs a visual image for his mission, then he can feed that info to the OLS/IRST and get an infrared picture once it comes into range. So there are two functions: 1) correlation, and 2) feedback to sensors. Now, with the F-35, Lockmart is going a bit further.
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If you look at the process loop on the left hand side you will see the big difference is that the pilot has been taken out of it. There is a separate branch showing that he is fed fused information but all tasking of sensors is being done by the F-35’s computers using intelligent algorithms. Lockmart is trying to increase situational awareness even further by making it so that the pilot isn’t burdened with system management functions and can devote his/her full attention to the mission. So it is not true to say that the Rafale doesn’t have sensor fusion. It does – every bit as much as the Raptor or Typhoon. However, it is fair to say that it is being taken to the next level with the F-35. And it can do this because it is a much newer combat platform and has gobs more processing power and system bandwidth than Raptor or Rafale.
XB-70They are all somewhat different, and some are very different. Very generally speaking…
A traditional radar system uses radio waves for scanning. It uses electronic means to mix various waveforms to do the necessary upconversion, downconversion, filtering, modulation and such.
ROFAR also uses radio waves for scanning. But it generates them through optical methods. A laser is used to excite the “photonic” (optical) system to generate the needed RF signals for scanning. All upconversion, downconverison, filtering, and modulation is done optically.
LIDAR uses the laser directly for scanning. Amplification, filtering, and such is all done optically. (Both LIDAR and ROFAR may use a final electronic filter in between the photodiode receiver and the ADC)
A quantum radar doesn’t use electromagnetic energy at all; it uses entangled particles instead.
XB-70What is, if I may ask, a 6G platform?
That’s just it, it is so early in the design process for 6G that I don’t think anyone can fully answer that question yet. That’s why it is a bold statement. They are promising for it to do something when they aren’t even sure what that “thing” is yet. They certainly have some idea as it is clear that they are headed toward integrating new capabilities (that have been floated around as part of 6G). Self-diagnosis is the start of self-repair. Having DIRCMs means it has readily available apertures for installing more dangerous energy based weapons. The advancement of Russia’s drone capabilities (Tango posted an update on Okhotnik-B) can unlock the door for a “system of systems approach”. The questions are how well the Su-57 design can integrate such capabilities as well as how well can it integrate capabilities that might not even have been considered yet? (This won’t always be physical integration; it might sometimes be a separate platform which is integrated virtually in a “combat cloud”.)
I’ll just wait and see.
XB-70[USER=”31611″]Blitzo[/USER] – Her claim was ridiculous to begin with. She said that it both was ready for mass production and that it had “minor problems.” You aren’t going to mass produce an engine with known “minor problems” – nor will you fly it on a fighter. You fix them and verify the fix with testing first.
XB-70I’m going to keep this reply quick and reference back to your https://www.nature.com/articles/s41598-017-14306-y#Fig5 We are definitely talking about two different things. Specifically, there is selectable bandwidth and there is instantaneous bandwidth.
On the first read, It thought the 4.5-6.5GHz signal from the diode was its instantaneous pulse frequency band – which yields a 8GHz instantaneous bandwidth after the multiplier. Turns out it is its selectable band. Figure 3b or 3d (one is carrier the other is modulated signal) shows the full story, and it is really good for explaining your question. On 3b, you see 8GHz available bandwidth (selectable). The red line denote the instantaneous bandwidth as it sweeps over a period of 1 microsecond. For instance, at .5 microseconds it is centered at 22GHz and the instantaneous bandwidth (just eyeballing) is only around 200MHz.
I don’t know what state of the art currently is but you do want instantaneous bandwidth to be small – particularly for a stealth aircraft like Su-57. A RWR behaves similarly to the primary radar – its sweep performance would look very similar. It only looks through a narrow window in frequency (instantaneous bandwidth) as it sweeps over its selectable bandwidth. However, a RWR needs to be able to identify multiple potential threats and so it typically sweeps slower – but it can sweep/hop fast to try to keep track of a lock. So, since the trick is to prevent counterdetection while transmitting with radar, you have try to make it so that the opponent’s RWR sweep plot never overlaps with yours. And, although it is impossible to make this always true, you can maximize the odds by sweeping/hopping fast to try to prevent it from getting a proper track on your signal and also keeping instantaneous bandwidth low to lower the odds of overlap to begin with.
So, with proper growth and development, a ROFAR system could see use on a stealth fighter. But I would expect several years of work to be needed to address SNR concerns and also to develop ways to avoid high multipliers. (If they would have used a multiple of 18 then their instantaneous bandwidth would be 4.5 times as large and thus much easier to detect.) We’ll see what happens within the next 5-6 years.
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XB-70…they keep talking about the prospects of creating a 6G plane out of Su-57.
I think that is partly wishful thinking. I’m certain that they’ve got a good upgrade path lined up for it just like they had/have with the Flanker. And it seems to be an upgradable platform…it is likely only matter of time before the DIRCM dazzlers can actually do damage. And the brand new engine should be able to both provide upgrades in thrust as well as power generation for such luxuries over the span of its design life. But it will likely prove difficult, if not impossible, to produce a complete 6th gen platform from something that wasn’t designed from the ground up as such. The self-diagnostics system they have though is pretty creative. OTDR has been around a while but I don’t know if anyone has tapped it for this application before. It should reduce downtime a good bit.
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