F22 vs. IRST and radar jammers

Anything goes, as long as it is about the Lockheed Martin F-22 Raptor
  • Author
  • Message
Offline

mrbsct

Active Member

Active Member

  • Posts: 153
  • Joined: 27 May 2015, 00:26

Unread post27 May 2015, 00:30

I read on Defense issues by Picard578(a ridiculous avionic "expert" who shows a bunch of stats to make him look smart, then comes up with random numbers to support his own agenda against Lockheed Martin and the "military industrial complex", basically an internet Pierre Sprey), say that IRST is so effective now systems like the PIRATE can pretty much nullify stealth at 100 km on a frontal target to the point that IR stealth such as IR Paint makes zero difference and the F22's nozzles only increase rear stealth. Also I head ridiculous claims that modern ECMs can jam radar(even LPI AESAs) to the point they are only 1/3 their range(some number he pulled out with no support)

How effective is IRST? I know it is very stealthy since it cannot be detected or jammed, but the range comes into question. How effective are IR panels? Can ECMs really be that effective on modern radar like AESAs?
Online
User avatar

sferrin

Elite 5K

Elite 5K

  • Posts: 5333
  • Joined: 22 Jul 2005, 03:23

Unread post27 May 2015, 02:10

"LowObservable" get a new handle or something? :lmao:
"There I was. . ."
Offline

thomonkey

Enthusiast

Enthusiast

  • Posts: 74
  • Joined: 26 Dec 2014, 21:11

Unread post27 May 2015, 02:51

The f22 and f35 will get a radar lock on any non stealthy jet a long time before any irst is within range. I don't really think much has to be said besides that.
Offline

hornetfinn

Elite 2K

Elite 2K

  • Posts: 2769
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post27 May 2015, 08:22

Modern IRST systems are very good and can see targets long distances away. They can see very small heat differences and I'm sure that they can see F-22 or F-35 at fairly substantial distances away. However they are definitely affected by design features like nozzles, airframe and exhaust cooling and other IR reduction features. Any reduction in heat peaks is going to reduce detection and tracking range. It's impossible to tell how different heat signature F-22 or F-35 has compared to designs with minor IR reduction measures like almost any pre-5th gen fighter. IMO, it's likely that both have much lower IR signature but that's just a guess. Of course lighting up AB is going to make very bright heat source no matter what the aircraft in question is (although IR reduction measures would still have some effect).

IRST currently has some limitations like poor range resolution. Most IRSTs have quite poor magnification capabilities and thus can do target ID only at relatively short ranges. That also affects range resolution as range can be determined more accurately if there are more pixels available from the target. F-35 EOTS is an exception as it has similar magnification capabilities to targeting pods which have 5 to 20 times higher magnification capabilities to IRST systems.

One thing to notice is that most capable IR sensor cores (which set the performance of the IRST systems) are produced by USA, then folled by France, UK, Japan, Israel and Germany. Possibly include South Korea and maybe Taiwan in the list as well. After that there is huge gap before China and Russia in producing IR sensor cores. So the threat of IRST systems is rather low currently as potentially hostile countries don't have technology to produce really modern IRST systems. For example OLS-35 in Su-35 is still nowhere as good as AN/AAS-42 produced for F-14D over 20 years ago.
Offline
User avatar

KamenRiderBlade

Elite 2K

Elite 2K

  • Posts: 2635
  • Joined: 24 Nov 2012, 02:20
  • Location: USA

Unread post27 May 2015, 08:56

sferrin wrote:"LowObservable" get a new handle or something? :lmao:


No, he had a kid with a foreign lover to train to follow his footsteps.
Offline

hornetfinn

Elite 2K

Elite 2K

  • Posts: 2769
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post27 May 2015, 09:19

Any radar can be jammed totally given enough power. If one could jam AESA to the point that it could only see 1/3 of the non-jammed range would mean that non-AESA radar would not see anything but noise and false targets. Besides, the effective jamming range depends heavily on the RCS of the target protected by the jamming.

Let's assume that advanced 4th gen fighter with AESA confronts 5th gen fighter with AESA. Both have identical radar performance and identical jamming system. Since 5th gen fighter will have say 100 times lower RCS, it can be detected it can be detected/tracked about 1/3 the range 4th gen fighter can be detected/tracked when no jamming is present. With jamming employed have the same comparative jamming performance (still maintain 1:3 range advantage) using 1/100 of the power required to protect advanced 4th gen fighter. Alternatively it can jam the 4th gen fighter radar so much that it can detect or track the 5th gen fighter at less than 1/10th the range 5th gen fighter can detect/track 4th gen fighter (assuming both use all the jamming power in their jamming systems).

Of course 5th gen fighters have much more jamming power available due to integration of AESA antenna and EW suite. For example F-35 is said to have 10 times more jamming power any legacy fighter has ever had:
https://www.f35.com/about/capabilities/electronicwarfare

While F-35 is capable of stand-off jamming for other aircraft — providing 10 times the effective radiated power of any legacy fighter — F-35s can also operate in closer proximity to the threat (‘stand-in’) to provide jamming power many multiples that of any legacy fighter.


It could be argued that F-22 and F-35 have better than 100 times lower RCS than advanced 4th gen fighters and along with much more jamming power, the net effect is something unbelievable. Even AESA radar which seems impervious to jamming against 4th gen fighters might be severely affected when trying to detect F-22 or F-35 due to combination of very low RCS and high jamming power.
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1705
  • Joined: 27 Mar 2015, 16:05

Unread post27 May 2015, 14:46

Due to the principles that they work, deceptive jamming are quite useless against AESA radar

The deceptive jammer received enemy incoming RF signal , it analyse , and then re transmitted that signal with different characteristic , like different doppler , pulse width . In contrast to noise jamming, deception jammer tries to mimic the radar echo so that the radar will respond as if it is receiving an echo from another aircraft or ship.


So deceptive jamming have to receive and process signal before they can send out jamming signal
Here are some characteristics of AESA radar that make them very resistance to jamming : frequency agility , and random PFR , random scan pattern
Jamming is likewise much more difficult against an AESA. Traditionally, jammers have operated by determining the operating frequency of the radar and then broadcasting a signal on it to confuse the receiver as to which is the "real" pulse and which is the jammer's. This technique works as long as the radar system cannot easily change its operating frequency. When the transmitters were based on klystron tubes this was generally true, and radars, especially airborne ones, had only a few frequencies to choose among. A jammer could listen to those possible frequencies and select the one to be used to jam.
Most radars using modern electronics are capable of changing their operating frequency with every pulse. An AESA has the additional capability of spreading its frequencies across a wide band even in a single pulse, which equates to lowering the emission power, making jammers much less effective. Although it is possible to send out broadband white noise against all the possible frequencies, this means the amount of energy being sent at any one frequency is much lower, reducing its effectiveness

http://self.gutenberg.org/articles/aesa_radar


In general, high PRF radars are more resistant to ECM because their average power is greater. Changing the PRF in a random fashion is an effective counter to deception because deception ECM depends on predictability of the radar. However, because PRF is related to the basic timing of the radar, this technique results in additional complexity and expense. Random PRF has been employed as a very effective ECCM feature in some radars for many years and has the additional benefit of elimination of MTI radar blind speeds.

Scan pattern. The radar scan pattern can influence ECCM capability because it influences the amount of energy directed toward the radar target. An active tracking phased-array radar is quite ECM resistant because of its ability to rapidly scan its radar beam in a random fashion than in the regular circular or sector scan pattern of conventional radars. This irregular beam positioning would give the opposing ECM system little or no warning and make it impossible to predict where and when to transmit false signals. In systems where scanning is performed in the receiver rather than in the transmitted beam, such as those mentioned in the section on angle deception, ECM has no direct access to the radar scan pattern and thus has difficulty using that information to interfere with the radar system operation.

Frequency. Frequency agility is a significant ECCM design feature. Using components such as frequency synthesizers (something like those employed in radio scanners) instead of conventional crystal-controlled oscillators, some radars are able to change frequency within one pulse repetition time (PRT). This makes deception and jamming very difficult. The radar can be designed to change frequency automatically within a certain range, or this can be done manually.

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

To effectively jam an AESA radar, you would need to use noise jamming. For a noise jammer to be effective , the signal to noise ratio that enemy received must be less than 1. To achieve that you either have to increase your jamming power or reduce your reflected signal , or both. F-35 use APG-81 to jam, AESA have very narrow beam, as a result jamming power are more focused at enemy's place. It's also have a tiny RCS, thus reducing the reflected signal significantly
Even if we assume both side use the same kind of jammer, it still much easier for a stealth fighter to jam a normal fighter's radar than the other way round. Here is why :

Image
not only that lower RCS reduce burn through distance , jamming power required will decrease in the same rate as RCS reduction ,50% reduction in RCS = 50% less power required to overwhelm real radar reflection with noise ( you can work it out for yourself , 99.9% reduction in RCS= 99.9% less power required to achieve same level of effectiveness , and so on )
now let take example of 4 aircraft :
1) B-52 : RCS = 100 m2
2) Mig-31 : RCS = 10 m2
3) Mig-35 : RCS = 1 m2
4) F-35 : RCS = 0.001 m2
now compared them :
from B-52 to F-35 then RCS is reduced by 99.999% =>99.999% less power require
from Mig-31 to F-35 then RCS is reduced by 99.99%=>99.99% less power require
from Mig-35 to F-35 then RCS is reduced by 99.9% =>99.9% less power require
( if you not good at math then use this http://www.percentagecalculator.net/ the lowest row )

so again a very powerful enemy radar : if F-35 need 5 kW jammer to shield it's radar reflection with noise signals then Mig-35 will need a 5 MW jammer , Mig-31 will need 50 MW jammer , B-52 will required 500 MW jammer , you can argue that bigger aircraft can carry more powerful jammer but remember even the SPY-1 only have power of 5 MW
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1705
  • Joined: 27 Mar 2015, 16:05

Unread post27 May 2015, 15:23

Picard and many people in anti F-35 group wrongly believed that fighter will be detected, lock and shot down the instant they turn on their radar thus lead to their conclusion that Radar and low RCS have little use and Optic sensor along with low IR signature are the more important
However, they are wrong because :
RWR doesn't always help aircraft detect enemy's radar before themselves get detected ( even though they have the advantage that the signal only have to travel one way)
Firstly, modern AESA implement several method to make their signal appear like background noise to enemy's RWR ( due to the fact that they change frequently every second , have random scanning pattern,compress their pulse .. etc)
Image
http://www.mar.mil.br/caaml/Revista/2007/Ingles/10-Pag40.pdf
Image
http://www.emrsdtc.com/conferences/2004/downloads/pdf/tech_conf_papers/A14.pdf

Secondly, even though RWR only have to listen to signal that travel one way, thus giving them 80 dB advantage compared to radar that have to detect reflected signal that travelling 2 ways, because of that in theory aircraft carry RWR should be able to detect Radar twice the range the radar can detect them if 2 side have equal sensitivity . In real life radar could be alot more sensitive than RWR because they have better gain . Here are reason why radar antenna have better gain :
1. RWR antenna typically has a gain of about 0 dB due to wide angular coverage. Fighter AESA radar has a gain of roughly 40 dB. This means instant 40 dB advantage to the radar.

2. Radar can operate at much narrower bandwidth as it knows the frequencies it uses and RWR does not and has to operate at much wider bandwidth. RWR receivers have a sensitivity in the region of -40 to -60 dB while radar receivers have a sensitivity is roughly about -100 dB with digital receivers achieving even better sensitivity like -120 dB.

This can give additional 50 to 80 dB advantage to radar depending on exact design of the systems involved. As AESA has a very wide total bandwidth, RWR must cover that very wide bandwidth leading to much less sensitivity. As the radar signal has a quite narrow bandwidth and radar can process only very narrow bandwidth giving large advantage in sensitivity. For AESA the advantage can be for example in the 60 to 80 dB range.

3. Radar can code or modulate the signal so that it achieves significant processing gain over RWR. Either phase or frequency modulation/coding can be used. As radar knows the coding, it can filter out the signal from noise using matched filters. The RWR can’t know the coding and this gives the radar another big advantage in total gain. This is called Processing gain and it can be tens of decibels. The more complex the coding the larger the processing gain of radar is. Modern AESA radar using Digital Beamforming can use very complex coding schemes and basically only processing power and software is the limit here. A simple calculation about processing gain is dividing the spreading bandwidth (bandwidth where the signal is spread) with actual signal bandwidth.

4. When the radar main beam is not directly pointing towards the RWR, then it will only be seen through sidelobes. Given that sidelobe level can be lower than -50 dB in AESA radars (about -20 to -30 dB in fighter MSA/PESA radars), this gives the radar a healthy advantage against RWR/ESM systems which it’s not painting. This means RWR will only see very short flashes of main beam and makes it more difficult for the RWR to work effectively.

Calculated together, radar can suddenly have well over 100 dB advantage over RWR system through mainlobe and over 150 dB advantage otherwise. There are ways for RWR/ESM systems to get some of that back and of course the race is never ending. RWR/ESM system can use more directional antenna, more sensitive receivers and higher processing power.[code][/code]


---------------
It also important to remember that even if your RWR, ESM system managed to detect enemy fighter's AESA radar, the only thing you know is bearing, it very hard to measure range for a missiles launch solution . Geolocated enemy aircraft by ESM, RWR is alot harder than geolocated ground target
First let see how a modern RWR, ELINT can geolocate a ground radar to generate fire solution for anti radar missiles :
there are 6 ways:
Image
Image
however you cant really use most of them to geolocated an aircraft
here is why :
1- triangulation method required target to be stationary , and take very long time
2- Azimuth / Elevation method will not work because you dont know enemy fighter altitude ( for a ground target you know the altitude is 0 ) thus cant use the Sine and Cosine function to work out the distance to target
3 - Time different arrival method required at least 3 aircraft stay at significant distance from the other ,but doesnt work well again AESA radar due to it very small side lobe , and thin beam, it also required many aircraft working together
4- determine distance by signal strength : required to threat radar characteristic to be known , and still doesnt work again modern AESA radar because they can managed transmitting power at short range to reduce probably of detection

there are some 2 additional methods to determine distance by RWR included :
5- phase rate change
6- RF doppler processing
they can be used again enemy's aircraft, using quite similar principles, will be discussed in the paper bellow :

http://subs.emis.de/LNI/Proceedings/Pro ... 54-222.pdf
http://users.isy.liu.se/en/rt/fredrik/r ... gsonly.pdf

Image
As you can see the method have many requirements such as
1) enemy's fighter fly at constant speed the whole time
2) enemy's fighter doesn't change heading the whole time ( the method measures range by calculate the changing of bearing between enemy fighter and ELINT aircraft when ELINT aircraft fly side to side " zic zack pattern" , thus it wouldn't be possible to apply the method if enemy fighter change heading and point their nose to ELINT aircraft direction all the time)
3)enemy's fighter will constantly emitting for the whole time needed for ELINT aircraft to measure range :
4) ELINT aircraft have to perform specific maneuver for a period of times to measure range
5) Accuracy is terrible , 20-40% error in range is very significant, at 100 km distance that is 20 - 40 km error, at 50 km distance that still 10-20 km error, that is even worse than long wave VHF radar thus not very useful for long range BVR engagement again enemy's fighter

How to counter RWR passive ranging :
let call the aircraft carry RWR sensor : ELINT aircraft

Method 1:
Image
To collect data for range measurement the ELINT aircraft must fly zigzag side to side to measure change in bearing , thus showing it's side aspect RCS to enemy's radar. And the S maneuver will only work if the enemy fighter fly straight and doesn't change their heading, fly at constant speed.
remember that side aspect RCS of any aircraft is very high (often in the range 20-30 dBsm or 100-1000 m2) , so the ELINT aircraft if wasn't detected by enemy radar earlier will be detected the moment it perform the S shape maneuver. Since most aircraft radar nowadays have no trouble tracking airborne target with RCS =100-1000 m2 from 300-400 km
So after detecting the ELINT aircraft, all enemy pilot have to do is changing their heading according to the heading of ELINT aircraft ( if the ELINT aircraft turn left, you turn left, if the ELINT aircraft turn right, you turn right, accelerate or decelerate to make your speed not constant)
that action will neutralise ELINT aircraft passive ranging ability


Method 2 :
Image
alot more simple, since the ELINT aircraft take at least 15 seconds of constant receiving enemy's radar signal to measure range with error about 25-40%, if enemy's pilot turn their radar on and off constantly, the ELINT aircraft wont be able to measure range in that case
modern AESA take 2-3 sec to scan it's whole FoV so you can turn radar on for 2 seconds and then off for 10 seconds then on again
and still have good tracking of target
Image


=> to sum up, RWR cannot replace Radar in air to air BVR engagement because they are alot more time consuming, less accurate, easily be neutralise by enemy tactics
Offline

mrbsct

Active Member

Active Member

  • Posts: 153
  • Joined: 27 May 2015, 00:26

Unread post27 May 2015, 16:33

^Doesn't F22 RWR ALR-94 have 360 coverage? A read by Military Expert and Aviation magazine editor Bill Sweetman, the ALR-94 can not only passively receive but cue the APG-77 to make it even more LPI, and even lock on to targets whether they are generating radar or not.

eloise wrote:
To effectively jam an AESA radar, you would need to use noise jamming. For a noise jammer to be effective , the signal to noise ratio that enemy received must be less than 1. To achieve that you either have to increase your jamming power or reduce your reflected signal , or both. F-35 use APG-81 to jam, AESA have very narrow beam, as a result jamming power are more focused at enemy's place. It's also have a tiny RCS, thus reducing the reflected signal significantly
Even if we assume both side use the same kind of jammer, it still much easier for a stealth fighter to jam a normal fighter's radar than the other way round. Here is why :

So stealth fighters not having dedicated jammers but use their own radar to jam are more effective than dedicated jamming systems like the SPECTRA?
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1705
  • Joined: 27 Mar 2015, 16:05

Unread post27 May 2015, 17:06

mrbsct wrote:^Doesn't F22 RWR ALR-94 have 360 coverage? A read by Military Expert and Aviation magazine editor Bill Sweetman, the ALR-94 can not only passively receive but cue the APG-77 to make it even more LPI, and even lock on to targets whether they are generating radar or not.

RWR of any fighter in general have 360 coverage , and yes they can be used to cue the radar or IRST sensor to focus at a specific angle, bearing thus allow them to have longer detection, tracking range

however in most case RWR cant generate fire solution again enemy's fighter by themselves due to the lack of ability to measure range to moving air target
( i have stated the way RWR can be used to passively measure range and the counter measures above)
the reason why the ELINT aircraft in my example have to fly zic zack left and right to measure range isnot because it's RWR dont cover 360 degree, but because it need to know the changing in closure rate in respect the change in bearing to measure range ( sorry if it still sound a bit confusing )
mrbsct wrote:So stealth fighters not having dedicated jammers but use their own radar to jam are more effective than dedicated jamming systems like the SPECTRA?

Delicated jammer is a really vague term . Aircraft ESM systems consist of receiving antenna , the central processor, and the transmitting antenna. The receive components on Rafale is SPECTRA, on F-35 is Asq-239. They both have central processor to detect, classify, generate jamming technique. however the transmitting part is a bit different, on Rafale the jamming signal is transmitting through the antenna spread through the aircraft airframe. On F-35 the jamming signal is transmitting through the radar T/R modules or towed decoy such as ALE-70. The advantage of SPECTRA is that jamming signal can be transmitted to any direction, the advantage of using APG-81 as a jammer is that jamming signal will be more powerful and focused due to better gain of radar. Also, the main reason that make stealth fighter's jamming more effective is their tiny RCS compared to legacy fighter
hope that clear up
Offline

mrbsct

Active Member

Active Member

  • Posts: 153
  • Joined: 27 May 2015, 00:26

Unread post27 May 2015, 23:21

I believe the F22's RWR the ALR-94 can provide accurate data for attack.

Journal of Electronic Defense; Bill Sweetman

The F-22 represents a radical departure from the traditional approach to EW. Passive systems, once considered to be defensive in nature, are now critical to detecting, tracking and even attacking the target.

High-priority emitters -- such as fighter aircraft at close range -- can be tracked in real time by the ALR-94. In this mode, called narrowband interleaved search and track (NBILST), the radar is used only to provide precise range and velocity data to set up a missile attack. If a hostile aircraft is injudicious in its use of radar, the ALR-94 may provide nearly all the information necessary to launch an AIM-120 AMRAAM air-to-air missile (AAM)

But aren't radar based jamming more prone to be detected by RWR and can risk an attack from anti-radiation missile?

Here is a quote from Air Power Australia:
Currently classified capabilities such as the use of the APG-79 or APG-81 AESA radar as an X-band high power jammer against the Russian BARS or Irbis E radar are not a panacea, and may actually hasten the demise of the F/A-18E/F or F-35 JSF in a BVR shootout. This is for the simple reason that to jam the Russian radar, the APG-79 or APG-81 AESA radar must jam the frequencies being used by the Russian radar, and this then turns the APG-79 or APG-81 AESA radar into a wholly electronically predictable X-band high power beacon for an anti-radiation seeker equipped Russian BVR missile such as the R-27EP or R-77P. The act of jamming the Russian radar effectively surrenders the frequency hopping agility in the emissions of the APG-79 or APG-81 AESA radar, denying it the only defence it has against the anti-radiation missile. A smart Russian radar software designer will include a "seduction mode" to this effect, with narrowband emissions to make it very easy even for an early model 9B-1032 anti-radiation seeker.
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1705
  • Joined: 27 Mar 2015, 16:05

Unread post28 May 2015, 04:39

mrbsct wrote:I believe the F22's RWR the ALR-94 can provide accurate data for attack.

If you read the article more careful , it does say ALR-94 provide nearly all but not all information required for missiles launch , radar still needed for velocity and distance measure


Journal of Electronic Defense; Bill Sweetman

The F-22 represents a radical departure from the traditional approach to EW. Passive systems, once considered to be defensive in nature, are now critical to detecting, tracking and even attacking the target.

High-priority emitters -- such as fighter aircraft at close range -- can be tracked in real time by the ALR-94. In this mode, called narrowband interleaved search and track (NBILST), the radar is used only to provide precise range and velocity data to set up a missile attack. If a hostile aircraft is injudicious in its use of radar, the ALR-94 may provide nearly all the information necessary to launch an AIM-120 AMRAAM air-to-air missile (AAM)

( it very easy for a RWR to geolocate a stationary ground target , again a moving air target that is a whole different story)

mrbsct wrote:But aren't radar based jamming more prone to be detected by RWR and can risk an attack from anti-radiation missile?

Here is a quote from Air Power Australia:
Currently classified capabilities such as the use of the APG-79 or APG-81 AESA radar as an X-band high power jammer against the Russian BARS or Irbis E radar are not a panacea, and may actually hasten the demise of the F/A-18E/F or F-35 JSF in a BVR shootout. This is for the simple reason that to jam the Russian radar, the APG-79 or APG-81 AESA radar must jam the frequencies being used by the Russian radar, and this then turns the APG-79 or APG-81 AESA radar into a wholly electronically predictable X-band high power beacon for an anti-radiation seeker equipped Russian BVR missile such as the R-27EP or R-77P. The act of jamming the Russian radar effectively surrenders the frequency hopping agility in the emissions of the APG-79 or APG-81 AESA radar, denying it the only defence it has against the anti-radiation missile. A smart Russian radar software designer will include a "seduction mode" to this effect, with narrowband emissions to make it very easy even for an early model 9B-1032 anti-radiation seeker.

No radar based jamming are not anymore prone to be detected by RWR than a normal jammer like ALG-184 or Spectra .
However , you are right about the part that when you use jamming , you are at risk get attacked by anti radiation or HOJ missiles .
That being said however : noise jamming to denied enemy ability to attack you by over saturate their receiver with noise signal , what does that mean : it mean enemy will know your direction , but they wont know the distance to your aircraft or your velocity , aspect angle .If they still decided to launch missiles anyway without knowing the range, speed then their missiles will have to fly a direct path rather than an arcs like they normally do thus reducing their range and terminal velocity significantly , moreover missiles in HOJ mode ( or anti radiation missiles ) will home at the radiated source without knowing direction the enemy going , aspect angle or speed of target thus they are unable to do a lead intercept and that will further reducing their PK again maneuver targets .
the threat from anti-radiation missiles could also be solve by using a FOTD . For example : ALE-55, TRD, X-Guard, ALE-70.. etc or an automous jamming UAV such as MALD-J to do the jamming work .

Anti-radiation missiles can also be defeated very easy by a simple tactic : jamming in turn ( not sure if i remember the tactics name correctly but it have been used since Vietnam war again anti radar and HOJ missiles )
As we know missiles in HOJ mode doesn't know the speed or range to target, it just home at the radiated signal ( basically like an anti radar missiles)
As long as there are 2 jamming asset fly at a certain distance from the other , they can turn their jammer on and off , in turn to attract and defeat the enemy's missiles,
For example : Imagine this : 2 fighter get in detection range of a SAM site. Fighter A start jamming to neutralise enemy radar. SAM crew decided to launch missiles in HOJ mode to counter that. When the enemy missiles home on the fighter A direction, the pilot of it will turn off his jammer, fighter B will turn jamming on , missiles will now steer to the direction of fighter B , now the fighter B turn off jamming and the fighter A turn on jamming again... etc very quickly after 1-2 time the SAM or AAM will run out of fuel and fall down the sky
P/s: the same thing can be done by 2 f-35 or 1 F-35 carry a MALD-J
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1705
  • Joined: 27 Mar 2015, 16:05

Unread post28 May 2015, 04:57

Also , while radar guide air to air missiles often have HOJ mode to deal with the situation when jamming is too heavy , a delicate anti radiation missiles ( something like R-27P , R-27EP ) are very close to useless again fighter because :
1) unlike an AWACs , fighter's radar only have FoV of about 60 degree , which mean the missiles will fly unguided the moment enemy fighter turn it's nose to other direction
2) unlike a ground radar , a fighter is moving very fast , when the ground radar turn off while the anti radar missiles still in mid fly ,the anti radiation missiles can use INS to guide itself to fly into the last known location if the radar , because ground radar are either stationary or moving very slow so that tactic would work. But again a moving aircraft , that tactic is close to useles.
Last edited by eloise on 28 May 2015, 10:09, edited 1 time in total.
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1705
  • Joined: 27 Mar 2015, 16:05

Unread post28 May 2015, 05:55

optical sensor ( IR, EO) also have a few weakness that stop them from replacing radar as the main sensor :
1) optical sensor may have very long detection range ( aas-42, private can reach out 200 km) but their targeting range ( where they can give firing solution) are very short because it is limited by the range of LRF, often about 20-30 km
2) Optical sensor have to zoom ( focused) when they want to look at target far away, when zooming they have very narrow FoV, and the scan rate of optical sensor are significantly slower than an AESA / PESA radar
3) optical sensor are heavily affected by weather, cloud, smoke, enemy can fly near cloud to hide from them
Offline

hornetfinn

Elite 2K

Elite 2K

  • Posts: 2769
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post28 May 2015, 09:21

mrbsct wrote:I
But aren't radar based jamming more prone to be detected by RWR and can risk an attack from anti-radiation missile?

Here is a quote from Air Power Australia:
Currently classified capabilities such as the use of the APG-79 or APG-81 AESA radar as an X-band high power jammer against the Russian BARS or Irbis E radar are not a panacea, and may actually hasten the demise of the F/A-18E/F or F-35 JSF in a BVR shootout. This is for the simple reason that to jam the Russian radar, the APG-79 or APG-81 AESA radar must jam the frequencies being used by the Russian radar, and this then turns the APG-79 or APG-81 AESA radar into a wholly electronically predictable X-band high power beacon for an anti-radiation seeker equipped Russian BVR missile such as the R-27EP or R-77P. The act of jamming the Russian radar effectively surrenders the frequency hopping agility in the emissions of the APG-79 or APG-81 AESA radar, denying it the only defence it has against the anti-radiation missile. A smart Russian radar software designer will include a "seduction mode" to this effect, with narrowband emissions to make it very easy even for an early model 9B-1032 anti-radiation seeker.


That would not work very well if at all for many reasons:

1. Russian radar would totally surrender the main reason it is designed, detect and track targets. It would be obsessed with one target (the jamming APG-79/81) and would not be able to see anything else. As fighter aircraft usually operate in formations, this would make the Russian fighters dead meat. The jamming aircraft could be flying well behind the rest or use totally different flight path.

2. This tactic would be so easily countered, it's not even funny. The jamming aircraft could just alter the heading every 20 to 30 seconds and the missile range and pK would drop like a rock. Just refer to what eloise here has said.

3. F/A-18 or F-35 could sling AMRAAM far further with precise targeting info they'd get from their AESA radars than Russian aircraft could effectively fire their anti-radiation missiles with heading only information. Like eloise described, AMRAAM could be using lofting profile going for determined collision point. Anti-radiation missile would have to fly in straight line and always go directly towards target heading. This would mean AMRAAM has huge advantage in range, end-game maneuverability and probability of kill.

4. This proposed tactic seems to assume that the jammer would use huge amount of power right away and it's easy to detect. That's not how modern jamming systems work. Much more likely is that the jamming power is small (F/A-18) to extremely small (F-35) at longer ranges and power is increased as range decreases (as radar returns get stronger). Especially F-35 would need only minuscule amount of power to hide it or any accompanying F-35 from the radar. This very small amount of jamming power would be very difficult to detect from the background noise. Very likely the radar would decrease sensitivity as the noise is increased as it would not be able to differentiate jamming from background noise as they'd be very close to each other. Every radar does this as background noise is not static but varies a lot depending on many factors like day/night, weather, background (sea, ground, vegetation), clouds, birds etc.

5. Another tactic to overcome this easily would be using co-operative jamming where each aircraft in the flight would take turns to jam the target radar. As the aircraft would fly in formations that can be even tens on miles/kilometers, it would be impossible to engage any one of them with anti-radiation missiles.

All in all, this proposed tactic is extremely poor idea and I'm sure Russian professionals are not stupid enough to believe it would work. I think the Russian missiles are intended against larger stand-off jamming aircraft which would be relatively easy targets as they do not maneuver and emit a lot of jamming power. I doubt their effectiveness against more modern jamming systems (like Growler) which work much smarter.
Next

Return to General F-22A Raptor forum

Who is online

Users browsing this forum: sferrin and 6 guests