YJ-27 anti-stealth radar

planeman

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Just some pics I found on another forum:
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5_JY-27_antistealth2.jpg

1_JY-27_antistealth3.jpg

3_JY-27_antistealth4.jpg

1_JY-27_antistealth5.jpg


Personally I don't quite get how these things really work, the theory is cool to a point but it sounds like looking for a needle in a haystack.

Internet research:
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the land-based YJ27 meter-wave radar system and to establish a sea-air integrated anti stealthy aircraft earlier warning network.
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the detection range of the land-based YJ27 radar system is 330km. The latter has a measurement accuracy of 150m, azimuth approximately 1 degree, resolution range 600m and azimuth 5 degrees.
 
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crobato

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When you are looking for a needle in a haystack, you need a big magnet. That's precisely what this radar is for. Big, long wavelengths, that paint a huge brush over the sky.

Think of radars like paint brushes. Fighter radars with high frequency X and Ku bands, they're meant for precise work, like small brushes making very precise touch ups, working on hard to get corners and trim.

Big AEW radars with long wavelengths are like big roller covers, designed to spread out and cover area but not as precise.

Stealth is designed mainly to beat X band radar which is what fighters and many SAMs use, because of its precise tracking. But like with light and all electromagnetic radiation, wavelengths don't bend all in the same way. If you try to bend for X bend radar, it will not get the same result with a lower or higher wavelength. Thus "stealth' is always a compromise, you're making a design bet.

A metric wave early warning radar like this can detect VLO targets, unfortunately, its tracking won't be as precise. That will be the job of another radar, the fire control set, and that task will be much harder.
 

tphuang

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actually, this JY-27 is pretty old. YLC-20 is the newer anti-stealth radar that they developed (or cloned, since it looks similar to Vera-E). You can find all of this in the anti-stealth thread in this forum.
 

SinoForce

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A metric wave early warning radar like this can detect VLO targets, unfortunately, its tracking won't be as precise. That will be the job of another radar, the fire control set, and that task will be much harder.
Then you add bird migrations, clouds, lightning, solar radiation, civilian traffic, jamming, decoys, lousy training/budget, and you end up with a system that warns you of an attack by stealth planes every day of the week.
 

tphuang

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Then you add bird migrations, clouds, lightning, solar radiation, civilian traffic, jamming, decoys, lousy training/budget, and you end up with a system that warns you of an attack by stealth planes every day of the week.

not really, there are certain characteristics of a fighter jet that really can't be hidden either way. For example, how many birds or decoys or clouds can travel at supersonic speed?
 

SinoForce

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not really, there are certain characteristics of a fighter jet that really can't be hidden either way. For example, how many birds or decoys or clouds can travel at supersonic speed?
It's a long-wave radar. They are ludicrously inaccurate at figuring out the speed of individual targets in the clutter. That's why police try to get the radar guns with the shortest waves at the highest frequency they can in order to get a better measure of speed. BTW, supersonic (or at least jet-speed) decoys are commonplace - even china has them!

I'm sure the attacking stealth aircraft will change their speed, altitude, direction once they detect the radar (or already have a flight plan to evade it beforehand). The attack aircraft can "see" the radar at much longer ranges than the radar can "see" the aircraft because the radar wave has to bounce back to the radar antenna while the aircraft does not require a bounce to detect the outgoing radar signal.
 

tphuang

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It's a long-wave radar. They are ludicrously inaccurate at figuring out the speed of individual targets in the clutter. That's why police try to get the radar guns with the shortest waves at the highest frequency they can in order to get a better measure of speed. BTW, supersonic (or at least jet-speed) decoys are commonplace - even china has them!

I'm sure the attacking stealth aircraft will change their speed, altitude, direction once they detect the radar (or already have a flight plan to evade it beforehand). The attack aircraft can "see" the radar at much longer ranges than the radar can "see" the aircraft because the radar wave has to bounce back to the radar antenna while the aircraft does not require a bounce to detect the outgoing radar signal.
who told you JY-27 is the only anti-stealth platform they have? It's an entire network, including YLC-20 and some of the other YLC radars they have working on different bands. As for supersonic decoys, how many of them do you think the Americans can carry on their aircraft carrier? And how many of them do you think have the RCS of a F-22?
 

SinoForce

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who told you JY-27 is the only anti-stealth platform they have? It's an entire network, including YLC-20 and some of the other YLC radars they have working on different bands. As for supersonic decoys, how many of them do you think the Americans can carry on their aircraft carrier? And how many of them do you think have the RCS of a F-22?
Carrier groups can carry a lot of them because they use them for target practice. The decoys are basically cheap cruise missiles that can be made to fly an attack flight plan. None of them have an RCS of an F-22 because they are meant to force the PLAAF to scramble aircraft and activate defense systems because they can't afford not to. Imagine the radio talk between the chinese operators?

"Are those real air-launched cruise missiles or decoys?"
"Which/how many are the decoys?"
"Is that an F-22 that hasn't dropped external tanks or a decoy?"
"How come none of the targets so far are going supersonic?"
"Hey, I think our target# 69 is also target 96 in your system. Let's not double up on the same plane(s)."
"Oh my god. They are going supersonic and subsonic at random!"
"Several of our targets just dropped from the scope. Has anyone picked up anything new in this area, re-adjust settings now!"
"Send our fighters here. No, send them there. Oh my god, two just got shot down over here."
 

planeman

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As for supersonic decoys, how many of them do you think the Americans can carry on their aircraft carrier? And how many of them do you think have the RCS of a F-22?
Quite a few I imagine. Radar decoys were used to massive effect by the Israelis in 1982 and in a towed form by NATO in the Balkans.
 

Gollevainen

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I'm sure the attacking stealth aircraft will change their speed, altitude, direction once they detect the radar (or already have a flight plan to evade it beforehand)

So F-22 features a emergy shift which brakes the airspeed down to the level of bird flocks:eek: :eek: Wow!!!!! So that was the "brake this class in case of emergy" button:rolleyes: :rolleyes: ;)
 
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