Sure
BOTH of you did. You guys may not have used the exact word 'rigged', but you pretty much implied the same with comments like the exercise 'fed' the F-35 known signals or such nonsense. Like I said, I went away for one week, waiting for someone to post comments from foreign pilots who would corroborate what you guys asserted and --
ZILCH.
It is now two weeks and not a single witness.
And you are wrong.
BOTH of you
.
All this time, I have been waiting for something technically 'meatier' from anyone. And nothing came. You criticized the F-35 as 'flawed' or having a 'weakness' for its dependency on a threat library. As it turned out, your vaunted Rafale with the SPECTRA system also uses a threat library, which, by the way, I doubt you knew until I showed it to you. But never mind that for now.
All this time, %99.999 likely you do not know
WHY there is such a system of a 'threat library'. Sure, you can do an Internet search for it, but you will find nothing revealing other than the most shallow comments from journalists who barely know how to turn on a light switch.
To understand
WHY there
MUST be a 'threat library', you must, like the Matrix movies said, return to The Source. In this case, it is the foundation of radar detection principles.
So here we go, and once I am done, people will see that the Rafale with its SPECTRA system is not so vaunted, after all.
The foundation of radar detection and tracking is the pulse. Not the carrier frequency, but the
PULSE. With the pulse, we have two physical points in order to perform the necessary calculations: leading edge and trailing edge.
The two points are not just mere mathematical points but actual physical locations.
But here lies the
START of many problems...
See that little bump labeled ' Target Return' ? That is from a
'NON-STEALTH' body. Any 'non-stealth' body. That is a house next to a tall business building. Atmospheric attenuation -- losses -- works both ways. From the seeking ( threat ) radar to the target and from the target echo. The result is that small signal that are magnitudes less than the original pulse strength and
MOST of the time, got lost in background clutter.
Say what...??? A 'non-stealth' body was actually 'stealthy' ? Yes. All the way from WW II when radar first came.
What made the target echo signal usually lost in background clutter was because it was usually ignored. So it was not 'lost' in the truest sense of the word but 'lost' thru
FAILURE OF DEFINITION.
Then what the radar designers resorted to was defining the pulse to something that even a human operator could recognized. They did it by manipulating the three main characteristics of the pulse: amplitude, freq, and duration ( length ).
As radar operations gets more complex and widespread, pulse definition became inadequate and targets often got lost by both failures from the human operators and the radar computer to recognize unique definitions. So came the concept of the 'pulse train'. As each pulse can be made unique, so can a series -- or a train -- of pulses can be made unique.
Fig 2 from above is an example of a simplified pulse train and each pulse is unique. Just like a pulse, a pulse train has a leading edge and a trailing edge, except that the edges are actually points, physical and mathematical, of where a
PATTERN of unique pulses begins and ends.
Q: Why is there a pattern of pulses ?
A: Because of the potential of the seeking radar operating in an EM dense environment.
A
REPETITIVE pattern helps the radar computer recognizes its own signals as the signals echo-ed off a body.
There need not be any time gap between trains. As long as there is a recognizable pattern, the radar computer can 'see' its own signals from other signals in the area.
This is where the countermeasure concept of the 'threat library' came to be.
If the threat radar needs a pattern to recognize its unique signals, then that need can be used against it. A SIGINT mission must record a threat signals source over as much time as possible precisely because of the potential complexity of the pulse trains. The signals are analyzed to pick out the leading/trailing edges of a pattern train, then analyzed to pick out the leading/trailing edges of the individual pulses. There are separate circuits, software and hardware, for each task.
So in using the above pulse train example, for ease of simplicity for visualization, let us say that each pulse is one sec in duration and one sec of separation from each other inside that train. Total time is ten secs per train.
The SIGINT analysis would reveal this pattern over one hr, for example. In cataloging this pattern, we can say something to the effects of: 'If you see this pattern after 2 secs of duration, you are looking at the Binford X1R radar system.' Then we program this instructions into our threat library.
Now we compress the entire concept into millions of pulses in milliseconds of operations. But essentially, the concept is the same regardless.
What happens if we encounter a signal that is not in our library ?
I said 'signal'. Not any type of class of signals. Just 'signal'.
A Katy Perry song has repeating patterns, does it not ? So how would you recognize 'Roar' from a genuine threat radar signal ?
Let us return to this source for a moment...
https://www.darpa.mil/program/adaptive-radar-countermeasures
'Isolate unknown radar signals in the presence of other hostile, friendly and neutral signals.'
Implicitly, there are four types of signals encountered: known, hostile, neutral, and unknown.
If you are in a combat zone, not likely you would encounter Katy Perry's 'Roar' song. So we can reasonably assume that the unknown signal is either a radar signal or something relating to communication, for example.
What is this 'neutral' signal ? Is it 'unknown' ? No. It is known as defined in the threat library but is considered to be not directly supportive of a weapons system. An Identification Friend or Foe ( IFF ) signal is considered 'neutral' since all it does is query you of your status. Whether you are a 'friend' or 'foe' is up to the operator to decide. An IFF reply is often neither 'friend' nor 'foe' and confirmation must be thru other means, such as visual or radio conversation. In this case, the target is suspect in both 'friend' and 'foe' status. An automatic response of shooting at this target could have negative consequences like shooting at a civilian airliner. So an IFF query signal is classified as a 'neutral' signal.
Now we come to the over-hyped SPECTRA system as it encounters an 'unknown' signal.
SPECTRA samples a signal
BEFORE it comes to a conclusion...
https://en.wikipedia.org/wiki/Thales_Spectra
But sample the signal in what way ?
Let us return to this example of a pulse train...
There are five unique pulses in this train. Does SPECTRA sample 2 or 3 pulses before it make a conclusion ? If so, then SPECTRA is indeed a shitty execution of a sound concept. Since it does not know how long is that pulse train, its sampling
MUST BE OVER TIME in order to discern out a repeating pattern of five unique pulses.
How long is that sampling duration before it queries its own threat library ? Thales is not going to reveal that secret because that factor is core of the system. But the logic of statistics and the history of radar technology %99.999 expect that sampling mode to be time dependent instead of quantity dependent. Come to a conclusion after sampling of 3 pulses could have SPECTRA jamming a friendly or neutral signal.
So just because the Rafale's sales brochure tooted this horn of capability, that does not automatically make the Rafale a superior to the F-35 or even a 'more capable' fighter.
Let us look at this IEEE source...
http://ieeexplore.ieee.org/abstract/document/6159516/
Note the authors' names. I do not want to be accused of bias by using American/Western authors from a paywalled source.
Inter-pulses frequency agility (IPFA) often occurs in contaminated signals, whether the signal is music radio or threat radar. In this situation, that agility is accidental, not intentional like what the authors proposed.
This is a simplified example of what such a signal would look like...
There is no discernible pattern over time. SPECTRA must have a sampling time limit. That means SPECTRA could be jamming a signal that is 'unknown' but is a non-threat, thereby, the Rafale just gave itself away.
But let us say that the signal that has
DELIBERATE signal agility, not just in freq but also in other pulse characteristics, what will happens is that as SPECTRA stops its sampling and begins to create a countermeasure, the threat radar could be jumping to the next signature, making SPECTRA at least one signal behind. In other words, the Rafale would be painted by every other pulse, if not by every pulse.
SPECTRA cannot sample a signal in the way and the time duration that a dedicated SIGINT platform does it. The jet is in a combat zone being bombarded with all kinds of signals.
Here is what the Chinese authors of that paper said...
Note the highlighted.
The phrase 'parameter measurement function' means sampling. Radar detection has statistics as its core function and sampling is a core function of statistics. Ask any economist or financier or insurance actuary.
So against an 'unknown' signal, SPECTRA could be jamming a non-threat signal or being constantly behind the genuine threat radar. Sure, since the signal has no discernible pattern, that would put the threat radar at some disadvantages as well because it could not remember what it emits, but as long as it can sense some kind of return over time, it would be just 'good enough' for that adversary.
What does this means for the Rafale ?
It means that the Raffle is good against Tier 2 and 3 adversaries, but not against Tier One, like US. Second and Third tiers adversaries relies on threat radars that has repeating characteristics. The F-22 and F-35 with their AESA systems can generate radar signals that is both recognizable by the emitters and extremely difficult -- if not outright impossible -- for any ECM to classify.
China is working hard to become a Tier One opponent on her own. The Raffle is not going to cut it, no matter what the Frenchies says.
This is the longest explanation I posted regarding the Raffle and its SPECTRA system. It is long because in the past, people with common sense and intelligence quite understood what I said. You and the other guy seems to be the exceptions. And not in a good way.
We are not looking at the Raffle as example.
Let us return to this example...
In every radar system, there are two ranges: maximum and usable. The usable range is usually %75 of max. But let us be generous and say %80 for the sake of argument.
If a jet is inside the max but NOT YET inside usable, that does not mean its 'Target Return' signal is not detectable. The seeking radar does sees it but only as an inconsistent signal.
What we want for the F-22/35 is to be able to recognize an unknown signal as a legitimate radar signal even though it does not exists in the threat library. Not as a neutral signal even if that signal does not exists as 'neutral' in the threat library. We want to recognize the signal as a legitimate radar signal. SPECTRA assumes -- as radar -- by default of the signal being unknown in its threat library. We do not want to assume. We want to be %99.999 statistically certain that the unknown signal is a radar signal.
Totally different.
I have a few ideas on how but I ain't saying...
Ultimately, what this means is that the F-22/35 will be able to stay between that max and usable ranges with near impunity of being detected by any unknown/unclassified radar signals.
Someone will just have to be foolish enough to be the first test example. Any takers ?
That was no 'attack' against you.
Paywalled sources usually have more technical details than non pay sources. I usually do not use paywalled sources because I believe it is unfair to the readers because not everyone has the money, or the allowance by others such as an employer, to access such sources.
But in your case, your stubbornness made it an exception to my rule.
Based upon what I posted above regarding SPECTRA's need to sample, the higher the pulse count, the worse it is for the Raffle if the signal has any kind of signal characteristics agility.
The bottom line is this...
You have an emotional investment in denigrating the American 'stealth' fighters. I get that. And I even enjoy seeing that as I debunk your criticisms.
The differences between you and I are breadth and scope.
You focus on the jet. I focus on 'stealth'.
You focus on the Indian Air Force. I look at military aviation.
You focus on sales brochures. I stand upon the foundation of technical issues, like how I explained things above.
The Raffle is no match for the as-is F-35 and the F-35 has yet to come to its full potential.
