DRFM it`s the newst must hvae gadget

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13 years

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More and more voices say DRFM makes it harder to kill enemy aircrafts.

Although adding one to a MiG-21 will hardly make the fishbed an F-22, there is no discussion this added capability seriously complicates the calculus of the aggressor.

http://www.nationalinterest.org/blog/the-buzz/the-us-militarys-top-guns-the-air-have-big-weakness-14065

http://aviationweek.com/awin/us-navy-aims-curb-enemy-jamming

Whats your take on this ?

How can one defend against this ? To me it looks trickier then even the most stealth shapes

Original post

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4 years 3 months

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Well.. is DRFM a new form of jamming technique ?

Looking from what it stands (Digital Radio Frequency Memory) It's more like part of the ESM... So it samples enemy radar signal.. in much better fidelity than older technique Thus allow self protection or Standoff jammer to emit better "replica" of enemy radar signal. Thus it might be more difficult to distinguish from real signal at the radar's side.

As far as i know.. jamming techniques haven't evolved much.. counter monopulse technique such as Cross eye and some deception modes like gate stealting (RGPO or VGPO) are still pretty much valid technique and so on repeater jammer (smart noise etc)

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6 years 1 month

Posts: 2,014

More and more voices say DRFM makes it harder to kill enemy aircrafts.

Although adding one to a MiG-21 will hardly make the fishbed an F-22, there is no discussion this added capability seriously complicates the calculus of the aggressor.

http://www.nationalinterest.org/blog/the-buzz/the-us-militarys-top-guns-the-air-have-big-weakness-14065

http://aviationweek.com/awin/us-navy-aims-curb-enemy-jamming

Whats your take on this ?

How can one defend against this ? To me it looks trickier then even the most stealth shapes

DRFM isn't anything new, many jammer ( for exampleALQ -165, ALQ-211, ALQ-99, ALQ-131.. etc) have it, again radar with frequency hopping and random waveform, PRF characteristics , DRFM jamming is really really hard

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

Air Marshal Brown: I think if you have a look around on an F16 sometimes that is not wonderful either. But getting back to the situational awareness, the ability to actually have that data fusion that the aeroplane has makes an incredible difference to how you perform in combat. I saw it first hand on a Red Flag mission in an F15D against a series of fifth-generation F22s. We were actually in the red air. In five engagements we never knew who had hit us and we never even saw the other aeroplane at any one particular time. That is a current fourth-generation aeroplane.
The data fusion in the stealth makes such a difference to your overall situational awareness it is quite incredible. After that particular mission I went back and had a look at the tapes on the F22, and the difference in the situational awareness in our two cockpits was just so fundamentally different. That is the key to fifth-generation. That is where I have trouble with the APA analysis. They tend to go down particular paths in the aeroplane, whether it is turn rate performance or acceleration. These are all important factors, but it is a combination of what you have actually got in the jet and the situational awareness that is resident in the cockpit of a fifth-generation aeroplane that makes the fundamental difference…

To me that is key: it is not only stealth; it is the combination of the EOS and the radar to be able to build a comprehensive picture. In that engagement I talked about at Nellis, in Red Flag, the ability to be in a cockpit with a God's-eye view of what is going on in the world was such an advantage over a fourth-generation fighter—and arguably one of the best fourth-generation fighters in existence, the F15. But even with a DRFM jamming pipe, we still had no chance in those particular engagements. And at no time did any of the performance characteristics that you are talking about have any relevance to those five engagements .


http://parlinfo.aph.gov.au/parlInfo/search/display/display.w3p;query=Id%3A%22committees%2Fcommjnt%2Ffb49a6a2-5080-4c72-a379-e4fd10cc710a%2F0002%22

the passive targeting method mentioned in the article is also well known for age
http://forum.keypublishing.com/attachment.php?attachmentid=234423&d=1410232946
http://forum.keypublishing.com/attachment.php?attachmentid=233753&d=1410232995

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7 years 10 months

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Antiquated links...
Basics are for sure interesting, but author forgets more recent techniques allowed by calculation power like interferometry etc.

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6 years 1 month

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Antiquated links...
Basics are for sure interesting, but author forgets more recent techniques allowed by calculation power like interferometry etc.

measures the signal power to determine range would required you to know the exact kind of radar ( which is really hard again something that change frequency all the time) , and most modern radar can manage their power as well
p/s : if i remember correctly, interferometry measures phase rather than power

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7 years 10 months

Posts: 4,168

measures the signal power to determine range would required you to know the exact kind of radar ( which is really hard again something that change frequency all the time) , and most modern radar can manage their power as well
p/s : if i remember correctly, interferometry measures phase rather than power

Absolutely, but phase shift can allow time difference of arrival and azimth aswell as triangulation... I everything works perfectly well of course.

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19 years 11 months

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DFRM works by injecting memorized transmitter waveform into the large sidelobes of older radar systems. This "fills the sky" with false targets for older systems.

Sidelobes are minimal for new radar systems.

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6 years 1 month

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Absolutely, but phase shift can allow time difference of arrival and azimth aswell as triangulation....

phase rate change is basically triangulation, you still need 2 or more aircraft.
i find elevation method better

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4 years 3 months

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DFRM works by injecting memorized transmitter waveform into the large sidelobes of older radar systems. This "fills the sky" with false targets for older systems.

Sidelobes are minimal for new radar systems.

Source ?

Your description is much closer to a simple noise jamming rather than DRFM.

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13 years

Posts: 151

DFRM works by injecting memorized transmitter waveform into the large sidelobes of older radar systems. This "fills the sky" with false targets for older systems.

Sidelobes are minimal for new radar systems.

orly, so then why is this gentleman more than concerned about it ?

“We—the U.S. [Department of Defense]—haven’t been pursuing appropriate methods to counter EA [electronic attack] for years,” a senior Air Force official with extensive experience on the F-22 told The Daily Beast. “So, while we are stealthy, we will have a hard time working our way through the EA to target [an enemy aircraft such as a Russian-built Sukhoi] Su-35s and our missiles will have a hard time killing them.”

http://www.thedailybeast.com/articles/2014/12/04/pentagon-worries-that-russia-can-now-outshoot-u-s-stealth-jets.html

The an/apg-77 is no toy for sure

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6 years 1 month

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orly, so then why is this gentleman more than concerned about it ?

“We—the U.S. [Department of Defense]—haven’t been pursuing appropriate methods to counter EA [electronic attack] for years,” a senior Air Force official with extensive experience on the F-22 told The Daily Beast. “So, while we are stealthy, we will have a hard time working our way through the EA to target [an enemy aircraft such as a Russian-built Sukhoi] Su-35s and our missiles will have a hard time killing them.”

http://www.thedailybeast.com/articles/2014/12/04/pentagon-worries-that-russia-can-now-outshoot-u-s-stealth-jets.html

The an/apg-77 is no toy for sure


mikoyan if you pay attention , dailybeast always quoted some unnamed pilot or unnamed senior official :rolleyes: , do you know why ?, because they made thing up .If they made an actual interview , there wouldn't be any reason for them to leave out the name ,because that just reduced their credibility ( and if the news were classified then they wouldnt get it in the first place )
read the quoted text carefully ,you see it quite obvious that they make things up , basically state their opinion and put that in a quoted text

DRFM isn't new ,not at all , For DRFM to work, it has to detect a signal (radar pulse or pulses) to memorize and to generate the false targets. LPI radar on the other hand tries to hide the real radar signal in noise to counter that. The problem for jammer is that it doesn't know what kind of signal the radar is sending (mismatched filtering), but the radar of course does (matched filtering). This is not a problem with relatively simple radars as the signals they send are also simple and do not change. So once the signal is detected, it can be stored and easily used against the radar.

Modern LPI radar on the other hand does a lot of things to make things very difficult for EW systems. They send complex waveforms that is like noise and can only be made sense with filtering. The radar uses matched filtering as it knows exactly the characteristics of the radar signals it has sent (like frequency, PRF, modulation, pulse width). The EW receiver of course does not and must only guess the parameters and thus uses mismatched filtering. Even if the LPI signal is detected and stored, it is not that useful as the radar has already changed the signal parameters and the stored signal will not even give the radar extra work as it would not match the changed filters. AESA sets add the challenge of being able to quickly switch between every parameter at a moment's notice and very randomly, which will put the jammer behind the 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

and here is the quoted from an actual Marshall :


Parliamentary Joint Committee on Foreign Affairs, Defence and Trade - 16/05/2013 - Department of Defence annual report 2011-12

Air Marshal Brown:
But getting back to the situational awareness, the ability to actually have that data fusion that the aeroplane has makes an incredible difference to how you perform in combat. I saw it first hand on a Red Flag mission in an F15D against a series of fifth-generation F22s. We were actually in the red air. In five engagements we never knew who had hit us and we never even saw the other aeroplane at any one particular time
....
even with a DRFM jamming pipe, we still had no chance in those particular engagements. And at no time did any of the performance characteristics that you are talking about have any relevance to those five engagements .


http://parlinfo.aph.gov.au/parlInfo/search/display/display.w3p;query=Id%3A%22committees%2Fcommjnt%2Ffb49a6a2-5080-4c72-a379-e4fd10cc710a%2F0002%22

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9 years

Posts: 300

Drfm might not fool the latest generation fighters, but right now it is very effective in fooling current western fire and forget bvr missiles like the amraam. They might detect the hostile aircraft, but to shoot it down rather than having 1 missile to destroy it, 3-4 missiles would be needed. That is the current issue in countering Drfm jammers.

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9 years

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One of the event that triggered the drfm worry among the us forces (us navy especially) is when a planned fly by above uss George Washington by royal malaysian air force su-30mkm was spotted with sap-518 jammer pods.