Low power means short distance. If you broadcast at low power then you won’t see very far, because your signal won’t be strong enough. Noise isn’t magic.

low power in each frequency but total power still high

The necessity for L.O aircraft to have an AESA is they can control their emissions no matter their relative distance to an object/target. A F-35’s radar will be stronger at close range only if the pilot want it to be so.

read what i wrote careful again :confused: , iam not talking about the radar of F-35 , i was explain why it be easier for F-22 and F-35 ( compared to gen 4 , 4.5 aircraft ) to detect enemy’s AESA by RWR before they get detected themselves ( because they are stealth so the distance that the enemy can see them by radar be shorter => stronger signal => easier for them to distinguish between noise and the real signal from enemy radar by contrast non stealth aircraft dont have that advantages , so they may be detected , track by AESA radar at long distance before their RWR know that )

Electromagnetic waves properties will change depending on the medium they’re travelling in. That’s the reason why RADAR aren’t used for submarines. Depending on the frequency used (and we’re talking about slight variation whiting a given frequency, a X band will remain a X band) the electromagnetic waves won’t behave the same way. Just travelling through air will affect a wave depending on temperature, moisture, density etc. which mean the wave itself doesn’t travel in straight line… but in a wave lol. If you take into account the dispertion, the refractive index of the object being reflected on and the absortion, you’ll get very different measurements.

this is true but doesnot mean much here , i will explain why below

RAM will play mostly on the refractive index of materials as well as their absortive prioprieties in order to either trap, redirect or slow down as much as possible radar waves. Refraction occurs when a radio wave hits an object of a higher density than its current medium (in this case air). The radio wave now travels at a different angle—for example, waves propagating through clouds, as well as at a different speed.

1-refraction have nothing to do here ( i now what you mean but it simply will not going to make DRFM work better or your aircraft be more stealth )
2-“Electromagnetic waves properties will change depending on the medium they’re travelling in.”
even if the speed of the wave affected by RAM it will only be slow down when it traveling in the RAM material , in the other word once the wave coming back in air it will go with original speed
what you said before :

In any case due to the use of RAM on any modern aircraft and the laws of science that say the radar waves bouncing on an object will travel back much slower and with less strenght. If you add the RAM into effect, the waves will travel back even slower and with even less strenght meaning the ESM system will have plenty of time to calculate and emit a signal with the once bouncing back

this is completely wrong because
1-yes the wave speed affected by the medium it traveling in , if it travel in vacuum it be faster than in air , if it travel in air it be faster than in water …etc but that doesnot mean the wave keep the speed from the medium that it was traveling before ( read it carefully before you reply)
2- let me make an example :
+ speed of radio wave in air is about 299704644.53915 metres per second it is about 3*10^8 meter per second
+let assume the RAM of rafale can slow down the wave by 100 times the the speed of the wave is now 3*10^6 meter per second ( quite unrealistic as normally you can only slow the wave down by half )
+let assume the RAM thickness of rafale is 1 meter ( also unrealistic unless the rafale is as big as a destroyer this never going to happened )
+ so the time that the wave spend inside the RAM layer before coming back to air medium will be : 2/(3*10^6 ) = 6.6*10^(-7 ) = 0.0000006 seconds
=> even with super RAM , and unrealistic thick RAM layer there is no way that you can slow down the enemy’s radar wave enough to give ” ESM system plenty of time to calculate and emit a signal ” ;):D
Remember that RAM on aircraft are very very thin 1-2 mm thick , and radar wave will not travel through them but either get absorb or coming back so your theory about using RAM to slow down radar wave to give ESM system enough time to calculate is quite nonsense :p

DRFM can affect the medium around a aircraft as well as how the wave behave once they reach the aircraft by creating interferences. A very simplified exemple would be the larsen effect that can happen when you’re trying to sing to impress your date.

1-DRFM will not going to affect the medium around the aircraft
2-yes DRFM can create interference however unless your whole aircraft is a giant antenna that transmit signal from all over place then it will be effective , otherwise even destructive interference will not mean much because the amount of wave you can interfere by that method is too little :rolleyes:

Lol happy to see that we agree. So a EA-18G (a 4th gen BTW) can pose a serious threat to L.O platform, because L.O or not you still need to use you’re radar to engage your enemy. That’s the reason why IR systems are becoming so popular, and why the US is putting so much money into the F-35 ESM suite.

not really because broadcast noise jamming also make yourself a targets for ELINTS system they dont see you by radar but see , track you by RWR

Key word here is “less” leakage. Any active system can be detected and will be detected. One of the reason why high threat environnement will almost exclusively be treated with GPS guided munition rather than laser guided one (i.e B-2).

like i said many time before , it not really important whether enemy detected them or not , the important thing is at how far

Unless the pilot is using a special mode where the AESA broadcast in multi frequencies all at once, which I doubt is very useful, the Radar is more likely to use an unique frequency in each burst.

because the AESA made up from many T/R modules can work individually that why they more likely to broadcast at different frequency to maximize LPI , if they all at same frequency then it no different from normal frequency hopping radar ( which the AESA isnot exactly the same )

Your assemption are false. The F-22/F-35 won’t use an higher output unless they’ve already detected something, and a ESM system will likely detect a radar at least twice the useful range of the radar itself due to wave propagation.

what i mean is the RWR can see the signal from AESA radar but they will see it as noise because the signal is very low in power and spread over wide frequency , and because the F-22 , F-35 are stealth so the distance at which enemy radars can detect them will be much shorter than the distance the enemy radar can see a Rafale or EF-2000 , as a result the signal coming to F-35 , F-22 will be stronger (due to shorter range ) => harder to hide in background noise => easier to be detect by ELINT , RWR

DRFM uses many techniques to reduce the effectiveness of the enemy’s radar depending on its nature. Trying to fool an radar into thinking that no objects were detected might be pretty hard and require extensive intelligence on the radar’s specs.
In any case due to the use of RAM on any modern aircraft and the laws of science that say the radar waves bouncing on an object will travel back much slower and with less strenght. If you add the RAM into effect, the waves will travel back even slower and with even less strenght meaning the ESM system will have plenty of time to calculate and emit a signal with the once bouncing back. Of course it’ll not be that easy if it’s a radar you know nothing about. But few airforces will engage an enemy they know nothing about. That’s why modern airforces spend so much money on AEW&C/AWACS and other ELINT systems.

i really dont know any law that say ” the radar waves bouncing on an object will travel back much slower ” it impossible to make the wave travel back much slower

Even shaping and RAM don’t prevent the radar’s waves from coming back, they simply reduce their strenght by redirecting and absorbing most of it. DRFM won’t prevent the radar waves from going back either, but they’ll try to broadcast on the same frequencies used by the radar to make it much harder to process its own waves.

what i mean is the RAM , shaping prevent most off the signal from coming back to it’s radar either by redirecting or absorbing , by contrast for DRFM it will only send extra signal

Unless the emitting radar is using very low burst, and in which case limiting its own ability to see far, LPI or not any AESA based ESM system will get you eventually, especially if your adversary has been able to listen to you using satellites, ELINT aircraft (and I’m sure drones play and will play an increasing role here).

the problem is will it be able to see the enemy before they see you , and jamming can also be added to prevent ELINT system from seeing AESA radar
EX : adding EA-18G or MALD-J will make it almost impossible to see the AESA signal

Passive ranging using EODAS is listed as a feature of the F-35, but details of how it’s done or whether it requires 2 or more F-35s is not known.

:confused: havenot heard about this , can you give some link ? , btw how good is the resolution of DAS , how sensitive it is compared to the IR sensor of EOTS , does the DAS sensor have more resolution , more sensitive than sensor on missile like aim-9x , mica ,or A2G missiles likeSLAM-ER , NSM ?
, i think about triangulation using DAS as there are more 1 IR sensor so it seem possible

BTW the F-35 have like 5- 6 DAS sensor and 1 EOTS , does that mean that it can do passive ranging using those sensor :confused: ( triangulation just like what RWR do to calculate the range to ground radar )

the DAS hostile fire detection capability seem quite nice :p
http://www.f-16.net/f-16_forum_viewtopic-t-22377.html

There are different ways to market the RCS.

Russians go for a more average approach and while th US goes the other way in the marketing. Probably because the US (LM) can achieve lower minimum RCS while the russians can show a smaller difference by going for the average.

Alexander Davidenko: The F22 is in the 0,3-0,4 sqm range.

http://www.inosmi.ru/army/20100313/158588233.html

Either way I think the averages are a better measurement (just think about it as two AWACS 50-100km apart, one of them will get a good reading…).

If Sukhois numbers are somewhat accurate then an Su35 with Iris could track an F22 at over 100nm in a jam free environment.

They also claimed the Su27 to be a 12sqm target. That would be the right side on this diagram with the average frontal RCS.

(Yes, Sukhoi have the competence to judge competitors RCS figures since they have all materials, ll simulation models etc needed to do so. And since the PAK FA is made to counter the F22 they probably have made extensive research about it. So don’t just throw it away because its not from LM Spudman)

no support for these 3 assumptions i afraid
and to be far head on RCS is more useful to see if one aircraft is more survivable for attack , i mean if you look at an aircraft directly 90 degree from top of it or strange behind then it will have huge RCS ( even for sth like B-2 , F-22 ) but in real life there be little or no situations when the enemy do that ( unless they are dogfight when stealth are no longer useful )

Moon_light :

And by Spectra , by another Rafale or by any other fighter equipped with Link-16 , etc … BTW, Rafale demonstrated a 180* kill with a MICA using Link-16 target datas froim another Rafale in June 2007 :

“” complex combat scenario was created with a Rafale pilot being chased and threatened by an enemy aircraft (actually a C22 drone) approaching at a distance of several nautical miles from its rear sector. A second Rafale, acting as wingman, acquired the target and provided target designation information to the first aircraft via the Link 16 data link.

On being launched, MICA carried out an extremely sharp 180° manoeuvre in its inertial guidance phase, a manoeuvre made possible by the missiles exceptional agility provided by its thrust vector control feature. MICA then advanced towards the designated target which it destroyed. The MICA missile used during this training session was the RF variant, featuring an electromagnetic active seeker.””

That was a World first , 6 years ago .

i dont think this ability too special , F-35 can also do a 180* kill with it’s JHMCS and DAS even if there is only 1 F-35 , this ability of rafale is not quite useful , i mean if there is a second rafale he can simply attack the enemy with his missiles right :confused:

Moon , you said :

No . Google instantaneous frequency measurement :

“”Most radar warning (RW), electronic countermeasures (ECM) and electronic intelligence (ELINT) systems employ instantaneous frequency measurement (IFM) to identify threats, map the electronic battlefield and eventually implement deceptive countermeasures. “”
“”An instantaneous frequency measurement receiver is capable of measuring the frequency of each individual pulse in real time.“”

To put it simply , when the radar signal bounces on the aircraft , it can be manipulated in real time . This is what is called real time deceptive jamming .
Very few ECM systems have this capability .

frequency is manipulated in real time , doesnot mean there is no delay , no matter how fast is the computer it always take time to measure sth ( understand what i mean ? )
an AESA radar have 1000-1200 T/R modules , try to detect and jam them will not be easy ( like try to jam 1000 different radars) especially if there is background noise or jamming from other asset like MALD-J or EA-18G ..etc

How would you explain this :

The CATbird avionics testbed for the F-35 program has proved capable of detecting and jamming F-22 radars.

that only show that F-35 can detect and jam AESA radar , has nothing to do with system on rafale , and even this have not show at what distance F-35 can detect the AESA signal and jam it , how long does the computer take to measure and create jamming signal , not to mention in this situation there only F-22 and F-35 and no jamming asset so it will be easier to detect AESA signal (remember because the F-35 have much lower RCS compared to rafale so it always need stronger radar wave to detect it at the same distance => harder for the AESA to hide in background noise => easier for the F-35 to detect enemy’s AESA radar before it get detected 😀 )

Spectra also shows clever real time deceptive jamming , its using special DRFM techniques to lower Rafale ‘s RCS and do signal manipulation to fool the adverse radar into thinking that the echo is not its own original train pulse , so it ‘s not taken into account : no detection .

i havenot heard of any DRFM that can lower aircraft RCS , it will be useful if you can provide link for that , most DRFM sending false signals to make enemy radar believe there is many others targets either ahead or behind , slower or faster , have higher or lower RCS than the aircraft it self but it dont make the aircraft disappear , noise jamming by contrast overload the radar with it’s very strong signal so the aircraft disappear in the white screen

the line in red= :p i think you are wrong with this one , DRFM (or deceptive jamming ) actually try to look like enemy signal to fool their radar 😉 because if it dont it will be rejected
Example : the radar wave from F-35 go to rafale , it will bounces on the aircraft and come back , at the same time Spectra will analyze the signal and create false signal , send back to the F-35’s radar but no matter how fast is the computer on rafale it still need time to measure and create the signal , even if it only take 0.01 second ,the signal sent by Spectra still arrive to the F-35 radar slower than the real Apg-81 waves that bounces from the rafale airfame ( because they not start at the same time ), so the APG-81 will only reject the Spectra signal

=> this

do signal manipulation to fool the adverse radar into thinking that the echo is not its own original train pulse , so it ‘s not taken into account : no detection

is impossible 😎 , no matter what you do the signal create by APG-81 still comming back , you can try to over load the radar by noise jamming or create additional targets by deceptive (DRFM ) jamming but there is no way to stop the origin radar wave from coming back by electronic jamming ( by shaping or RAM then yes 😀 )
P/s :stealth using active wave canceled may be possible ( in future ) based on destructive interference however to be able to do it you have to make the rafale become a huge antenna that transmission come from all over the place at all frequency , however in that situation the Rafale will then have trouble with enemy’s RWR , ELINT ..etc

But , some clever AESA radars use encryption to code their signals and the echoes must be recognized as “true” . If not , it ‘s jamming and it is discarded by the radar : the jamming doesn ‘t work .
That means that the ECM system , to be able to jam such radars , has to work much harder . Obviously , cracking the code in real time is often impossible so the trick lies elsewhere . The ECM suite goes around the code , it simply doesn ‘t mind the code . It understands where the spikes across various frequencies are and it manipulates the coded echoes to make them “unreadable” by the radar . The AESA radar knows that something is around there but it can ‘t compute a firing solution .
The F-22 uses coded radar signals but the F-35 can jam it .

Cheers .

you can simply do this with barrage noise jamming 😎

in conclusion : iam not saying that LPI can’t be detect or jamming by RWR , ELINT system however the range at which they can be detect , jam will not likely be quite useful ( just like all radar can detect stealth fighter but not quite at useful range )

@ Moon_light ,

Your post #267 is good .
Now , the way the defeat LPI radar is to combine few techniques : a clever antenna array , a lot of processing power (number crushing) , ultra fast memory and a lot of it , Digital radio frequency memory (DRFM) and strong Fast Fourrier Transform algorithms (FFT) .
You try to lower the threshold but in doing so , you get tons of data , most of them being noise . A lot of processing power and strong FFT sort out the real echoes from the noise . Keep in mind that the RWR must listen on multiple bands at the same time , so you imagine the sheer amount of data the system has to process . Dedicated processors working in chain take care of it .
DRFM is used to :
-1) recognise the pulse train signal across various frequencies and memorize the “hops” .
-2) tell the system what to send back (and how) for jamming purpose .

Remember that the radar signal is stronger before to “hit” the aircraft than after the “bounce” . A LPI radar doesn ‘t use brute force because its goal is to be … LPI , so the power used to emit the pulse trains is low . This is important .
If the signal bounces onto RAM , the return is even weaker or can be inexistant . When the LPI radar listen for its pulse trains returns , these can be too low to be workable , its lost in the noise and can ‘t be retrieved .

the problem is how to know which echo is noise , which one is enemy’s radar wave , the radar know exactly which frequency it just transmitted so only wait for return from these frequency , by contrast RWR have to listen to all , echos above normal noise level are not always enemy radar it will have very hard time to solve this problem and even harder to measure range to target , doing such job RWR will required longer processing time than the radar because the job of Radar is easier ( assume that it can even do it :cool:)
EX : if the radar take 5 sec to give firing solution , then it may take RWR 15 – 20 sec to do that , not to mention F-35 can turn on- off it’s radar in interval to prevent enemy’s RWR from having enough time to detected or measure the range

You ask :

No . You need a special antenna equipped with multiple “listening connectors” , usualy 5 (or more) often disposed in a cross shape (like the “5” on a dice roll) . By mesuring the difference in phase of the incoming signal in beween connectors , I know with great precision where the signal comes from and I can do ranging as well if the system is top notch .

M2000 , Rafale , Typhoon , Gripen NG have 3 antennas of this type . The F-35 uses 10 antennas (!) over the leading and trailing edges of the wing leading and trailing edges of the horizontal tail.

can it measure enemy speed like radar ? ( new info 😀 )

Aurcov :

You forget that BVR , it ‘s the missile who does the killing , not the fighter . Replace the F-22 by a X-Wing if you want , it is still the Amraam who will try to do the killing . Jam the missile(s) and you survive the BVR combat , whoever the launcher is . Then , it is WVR combat with IR missiles and canon and this is a very different story .

Cheers .

you are right about this , but at least stealth aircraft have advantage in BVR , while super agile aircraft and normal aircraft quite equal due to JHMCs and dogfight missiles

I believe that only the TV channel of the FSO is limited to about 50km

Then trying to compare a engagement like Rafale/Typhoon against F-35 is most likely useless since any countries with enough money to buy these aircraft will also likely spend on AWACs or AEW&Cs making any advantage from a fighter aircraft’s radar rather moot. If you add all the other assets a modern army will deploy like ELINT/SINGINT aircraft, satellites, etc. you get a picture where if L.O does increase survivability indeed, it isn’t enough for you to hide very long.

If however that capability is so costly that you have to reduce other programs, reduce aircraft availability and reliability, then you end up with a very bad deal as it will in the end reduce your pilots survivability.

1-no i mean the range of the laser on the FSO , not the detection range
( actually it is 30 km rather than 50 km )
2- even AWACs can only see f-22 , f-35 at quite short range:cool: