it depends, if flare rejection is a processing rather than an optics thing then ASRAAM might have the advantage, or so i hear
Let face it, IIR is just gunna be IRCCM+. But probably still 1 flare defeat half the time
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The whole debate started due to missiles spesific purposes.
Since ASRAAM designed to be medium range missile like R27ET we made a debate about how easily it will get flared on long range shots like ET does.
Clearly you didn’t bother to read from the start.
I kinda fail to see why a focal-plane array which can be overblended should be more resistant to flares than a line scan seeker.
We’re getting both it doesn’t matter
I have not followed the entire discussion, I’m only responding to this comment.
In game, they would probably behave identically seeker wise. IRL, the ASRAAM has a significantly better seeker on paper, since it’s used a full 2D array instead of 2 1D array as on the IRIS-T. That’s kinda understandable has the ASRAAM needs to lock (and keep lock) at much greater distances than the IRIS-T
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from a recent greece pilot podcast, apparantly they prefer the IRIS-T over the amraam and basicaly stopped using the asraam after they got the IRIS-T.
THat being said i dont speak greece, that is what we have been told from a native
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Greece has ASRAAMs?
Genuine question, as I dont remember them having it.
i have no idea about the specifics,
Youtube auto translates sucks ass, and that is what we have been told
He says AMRAAM, doesnt he?
They also use the MICA on their mirage and rafales. There’s a probability they considered the MICA sufficient for long range, while the IRIS-T short range performance and cost effectiveness on their other airframes does not warrant the use of the ASRAAM
again, dont speak greece, that what we have been told
You can hear him say it. You can compare what he says to when he says IRIS later.
Also it lines up with the topic, of him talking about the Viper, That they use IRIS-T and AMRAAM on.
Greece never got ASRAAM (afaik), so it would be weird if he was talking about it.
ok wait i am an idiot, i checked again, yeah amraam not asraam, i confuised the context
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I still have yet to find something that backs the statement that a 2D focal plane array is better than a line scan device. AFAIK they decided against a 2D focal plane array because it had not enough flare resistancy in their opinion (overblending of neighboring lines, suspectible to LDIRCM because of the continous exposure to the source, etc.). The optical part should be idenpendent from the used CCD type (except for the needed actuated micro-mirror for line scan devices) so lock-on/view range (magnification) can be identical.
The only disadvantages a line-scan device as a seeker CCD has, is the more complex mechanics (actuated mirror) and the limited refresh rate, caused by the actuation and minimum duration charge-discharge cycle of the CCD pixels, which causes the IRIS-T to have a refresh rate of 80 Hertz → 80 times per second 64 lines are scanned, so 5120 mirror (or prisma, whatever was used) movements and charge-discharge cycles per second for the CCD.
Neat part: The two lines of the 128x2 CCD are shifted, so targets can’t fall between the pixels during the scan, especially small targets at great distance.
Thing is, you can also easily simulate a 1D array using a 2D array, so I struggle to understand how you could argue that it’s worse when it comes to flare resistancy, by just using certain parts of the seeker in the compute. The more « sensor » you have, the more complex the compute you can have in general imo.
I think where the IRIS-T might actually have better flare resistance than the ASRAAM is due to using 2 arrays of different wavelengths, while the ASRAAM only has a singular array (correct me if I’m wrong I’m not 100% certain actually of this) and thus is limited in that aspect.
The MICA has 2 2D arrays for example, and some French papers do discuss the advantages of looking through several wavelengths to discriminate countermeasures. This would combine both seekers advantages, but also come at a steeper cost
The problem is, that it’s virtual with no mechanical component. Yeah you can scan line per line with a focal plane array, but the optics are made so that the incoming light always hits the whole array and not a small line. So you will always have the overblending even if scanning line per line which is not the case of the IRIS-T as the optics move there and shift the focus. It’s a mechanical limitation of the optics and not the seeker CCD itself in this case (different types of CCDs need different optics).
That the IRIS-T uses two wavelengths would be news to me. AFAIK it only uses Indium antimonide as the CCD material with 1000 nm to 5500 nm sensitivity (near infrared).
Even a mechanical scan would still see some bleeding when not totally in focus tho, meaning that it would still see similar abherations as fixed 2D array in the « vertical » scan, and it would see identical abherations on the horizontal axis by virtue of being 2D (so, why didn’t they go with a single point scan then ?)
This is more a case of the optic itself creating abherations, not the sensor.
The argument that a 1D array can be better than a 2D array, all other things equal seems a bit silly to me. Kinda like arguing that a mechanical radar is better than an electronically scanned array radar (wink)
I think, like the radar argument, it’s mostly a question of how economical it is compared to the advantages this brings to the missiles (ie, for a missile of the cartegory of the IRIS-T, either tech would basically be identical, so it end up making more sense going for the 1D tech, which was most likely way cheaper despite using mechanical parts for late 90s tech)
Of course you will have some bleed but it would only affect one line + its neighboring two lines, not more or even the whole seeker as the focus is moved.
Single Point scan would be unfeasably slow so you compromise to a line scan and are able to ignore or shut off a few lines instead of the whole seeker. Of course ignoring just a single point would be better but it also would be slower by a magintude (Instead of 5120 scans per second with 128x2 it would have to do 327680 scans wit 2x2 pixel and four times that with only a single pixel) and uncomparably more complex to implement technically.
Apples and Oranges. This comparison would be valid if we would talk about LIDARs which today are only line scan with a single laser source or a future developement where every LIDAR pixel has its own laser source, but we’re currently talking about completely passive receivers without active components ^^
Technically both are 2D, just one is stepped while the other is all at once. A 2D line scan also has other advantages as the much smaller array (1/64 the size of a focal plane array with the same resolution) is much better coolable. Other stuff like the exposure time to LDIRCM of only a few microseconds per scan instead of being exposed constantly is also advantageous.
Yup ASRAAM is a MWIR seeker, atleast it was, we cant be sure because Block 6 changed the seeker.