I tried to find something regarding output signal Power of thos SAP-518, couldn’t find them.
But it says Field of signal is 60deg by 60deg, i’m not sure if this mean you can steer the jamming signal direction just like you can With ESA radar or if it means something entirely different.
AESA/PESA steer and focused their beam by delaying the wave between transmitting antennas (to cause destructive/constructive interference ) , phase different will be controlled to reinforce the signal in certain directions, and mute it in all others
unless SAP-518 was designed the same way as NGJ ( aka AESA jammer with many T/R modules ), i have to say it can only steer it’s beam mechanically ,and have wide jamming beam
from outer appearance SAP-518 have much smaller aperture compared to a APG-81 , Irbis-e (you can see that SAP-518 can be put on wing tip of fighter ) , it also able to transmitting in wide range of frequency (2-18 Ghz ) so not all the aperture are used for X band transmitter , Thus , it obvious that it have much much lower gain than a radar (smaller aperture = lower gain = wider beam = less focused power , just so you know for a radar , gain is more important than transmitting power)
60* 60 degree beam is very wide actually ,AESA radar of similar size to APG-81 , working in X band can easily have 1-2 degree scanning beam
If you suspect that there is an fighter out there, which uses X-band radar in a confined Ghz range, then it would automatical tune in to these Ghz.
Although the SAP-518 is not fully Integrated in the the Flanker Radar, the SAP-518 is fully digital, and does a wide number ig different tasks.
well , X band is from 8-12 Ghz , the SAP-518 could be tune to only jam frequency from 8-12 Ghz , but it wont be able to jam MADL or Link -16 in that case , the benefit is that since bandwidth is much narrower , the jamming power in each frequency is much higher ,
that being said , the radar still have advantage that it can transmitting wave in a single or a few exact frequency while the barrage noise jammer still have to spread it’s power over a range of frequency
For example : jammer will have to cover the whole bandwidth from 8-12 Ghz ( because we taking about barrage noise jamming ) , thus it’s power will be divided over a range of 4000 Mhz
by contrast a radar can choose to transmitting all it’s power in exact frequency , it can send first pulse in 8.12 Ghz , then jump to 10.33 Ghz , then back to 9.45 Ghz ..etc you know the catch , the point is it dont have to spreading it’s power
The Pilot do not have to micromanage what kind of band or spessific Ghz it want operate in.
The SAP-518 detects incoming signals through the radar and procede accordingly.
.
what you describe isnt barrage noise jamming ,but more resemble DRFM deceptive jamming
Besides standard noise jamming, one method used to decoy missiles is deceptive jamming (or DRFM) which have been used widely on many jammer such as ALQ-211, ALQ-184, ALQ-214. Some people (I.e. Kopp and Goon) see as the end-all in air-air warfare. However, repeater jamming depends on picking up the radar emissions of the missile/aircraft – if the ESM doesn’t detect the radar and recognize it (such as if the radar is AESA LPI set, APG-79, APG-80, APG-81.. etc ), it doesn’t have any signal to repeat back to the receiver, and so it can’t create false targets.
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
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
AESA radar characteristics such as random scan pattern, random frequency, random PRF all make it very resistance to DFRM deceptive jamming.
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
it was revealed by the RAAF a few months back in testimony to the Australian Parliament that DRFM jammers can be defeated easily by 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
Sign In
