Well, there is quite a lot of contradiction between stealth and performance, no argument here.
For supersonic missiles, compromises are simply that much larger, and achieving operationally measurable stealth performance is that much harder. On a single-use airframe, where overly expensive solutions are tricky - this is multiplied yet again.
Point is, reducing signatures(all of them) for a subsonic sea skimmer is not just doable, it plays into their strengths, comes cheap, and is absorbed pretty well by the efficiency of their air-breathing engines and lift.
Examples?
Datalinks can be picked up in principle, no doubt here, but they may be directional(as well as simply hidden behind ECM). Having your assets in the air allows these updates to be pretty hard to intercept.
Higher flying search is indeed unstealthy - and this is where modern(2010s) search algorithms and flight tame play in hand. A LRASM-like missile can simply search down low (which it is actually designed to do) - this is, assuming that there is something wrong with midcourse updates.
More like their navy is designed to perform as such - which is reasonable for their . Note, that regardless of that, parts of PLAN, PLANAF strike arm, and JASDF are specifically designed to perform no matter the situation. And, due to a change in situation - ROCAF now transforms into much more of a sea denial force, as opposed to sea control. Curious lil navy.
Examples?
Before that happened, early front aspect locks by heatseekers were made against supersonic targets: their plume "nimbus" is a good, hot target, which can really be only hidden by airframe(doesn't work well with supersonic missiles - too much to hide). Furthermore, cooling surfaces at supersonic flight at ranges important for ASCMs is very difficult, and I don't remember any examples.
Finally - all the same is true to a significant degree in radar spectrum as well - shock cones and plume reflect quite a lot. Even frontally.
Sort of. But for the 2020s, wast majority of ASCMs are subsonic - either fully or mostly(YJ-18). Only 3 navies in the world consciously embrace supersonic missiles as their primary ship-to-ship strike weapon - Russian, Indian, and now ROC navies. There is also a mixed case of Indonesia - and this is it.
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When we're talking about a weapon for a general purpose frigate of a navy aimed at equal fights (navy as a whole) - I, frankly, view the new YJ-83 as a "good enough" solution. Especially when many of its targets are actually quite small and nimble.
As for how PLAN views it - we'll see in a few years, I guess.
I don't know what you mean by 'operational strengths'. Frankly it sounds baloney to me. If stealth is tied to being subsonic, stealthy supersonic fighters won't be possible. Furthermore I can go on and say that sharper radomes, typical of supersonic fighters, along with swept back wings, the more extreme the angle, the greater is the collateral benefit in RCS reduction, even though the primary intention is to reduce drag.
The first jet fighter to exhibit low RCS qualities, like in not appearing in radar until it is close enough, was the MiG-21 during the Vietnam War. This discovery was put down by a scientist in the Soviet Union, is the first ever paper to describe the use of shaping to reduce radar reflection.
If you want examples, just compare the shape of the Oniks and the YJ-12 to things like the Harpoon, YJ-83, Tomahawk or the YJ-62.
It kind of dawns on me that you are not familiar with the idea of how shaping works to reduce RCS.
As for datalinks, if you are directional you would have to be using a phase array at least on the missile and the ground station. However, even as the missile is hit by the datalink beam, over a distance the beam is wide enough that the missile will only block a small part of the beam and the rest of the beam will extend to eternity until they get bounce back to the surface by atmospheric layers, in which case they can get picked up by something else. Even if you have a beam between A and B, if an atmospheric layer is between A and B, some of the RF might get reflected or scattered in all sorts of direction, even if most of the RF will be received by the target. Some of the communication RF can get bounced off the missile itself and becomes scatter.
I don't understand what you mean by an LRASM like missile searching down low. Searching down low with any drone or missile is straight out inefficient and requires far greater time and fuel to accomplish. Stealth is a zero factor to this.
I don't even know why you keep bringing in the LRASM in the first place, when the original premise is a conventional subsonic missile, like the YJ-83, versus a supersonic missile like the YJ-12. Or to be precise, the YJ-83 vs. the YJ-12. What's the advantage of using the YJ-83 over the YJ-12? You keep introducing the LRASM and its qualities to the YJ-83 as if the YJ-83 possesses them inherently. It does not. Not to mention that an LRASM missile is nearly twice as big as the YJ-83, and if you do so, it would require its own canister. If you want to use LRASM as a point of comparison, don't compare it to a Cold War era supersonic or a late '90s supersonic. You might as well compare it to a hypothetical supersonic missile designed in 2015 to 2020 using the latest electronics and metamaterials including composites and radar absorbent materials.
As for shock cones they are also highly angled, and if they did reflect as much as you say, then you would achieve even lower RCS since no radar wave would fall upon the fighter or the missile itself. The faster you go the more angled the cone gets. Again, the concept of directional shaping. As you get even faster the air begins to ionize and that will start absorbing radio waves on its own.
