SinoDefence Forum

Ambivalent

The Mk-99 illuminator can illuminate up to four targets at once if the targets are close enough together in azimuth and altitude, through a multiplexing technique. This has been the case since the first Ticonderoga went to sea. In a saturation attack it would be expected there to be sufficient targets inbound on the same azimuth at roughly the same altitude to make this technique workable. Target illumination is only for the final second of the engagement or less, not more. Mid course updates transmitted to each missile's inertial nav via the AN/SPY-1 antennas can bring the missile close enough to the target to make longer time illumination unnecessary.
Wolvie, the strap on IR sensor on SM-2 is not so effective, or necessary, for use against subsonic sea skimmers. It is there for tracking sea skimming supersonic missiles, who's heat signature will often give them away before they emerge over the horizon. Such missiles have extremely high airframe temperatures that make IR homing very accurate and reliable. We fly these successfully against Vandal and Coyote targets, both of which exceed Mach 2 at 15 foot altitudes in calm sea states. SM-2 and RAM are both very effective against such targets.
Btw, we fly stream raids of multiple targets against ships as part of their training.

Wolverine

Let's see a source. BTW, you are not a source. No offense, but I don't care what you claim that you've seen or done in the military. The Naval Institute Guide does not make ANY of the claims above, including how many targets the SPG-62 can illuminate or how long a target requires illumination. The only possibly relevant information it gives is for the SPG-62's predecessor, the SPG-51 (on pp. 320-322 of the 5th Edition), which has an illumination angle of "0.9 degrees" and a range of "200kyd", which I will assume is similar to the SPG-62. Any enemy missiles within that narrow arc and within range will be lit up, be it 1,2 or 100 quadrillion missiles. In real life 1 or perhaps a few missiles could be simultaneously lit up, but stating a specific number like "4" betrays an improper understanding of what an illuminator does. Especially a radar that is mechanically slewed both vertically and horizontally like the SPG-62, there is no way in hell you could possibly make 4 targets that cannot all fit inside that narrow illumination cone to be lit up even nearly simultaneously, like what a time-sharing PESA does. That illuminator will have to stay on target until interception occurs before it can slew over to cover any additional targets outside of its initial illumination cone. Perhaps you're confusing "illumination" with "tracking", which would also be wrong because the SPG-62 doesn't have the ability to track either.

Again, let's see a source.

Try attacking OTH targets without the IR sensor. For targets within radar coverage, the missile can choose between the IR sensor or the radar illumination and decide which to use, but for OTH targets, there is no radar illumination, leaving the IR sensor the only thing an SM-2 has to go by (and it would have to be updated and sent to its target basket by the SPY-1 based on information gathered from AWACS), and that's been the whole point of talking about the IR sensor in the current carrier debate.

Ambivalent

Wolvie, are you familiar with what is called Interrupted Continuous Wave Illumination? The AN/SPG-62 Illuminator is an ICWR illuminator. The principal with CW radars is they measure doppler shift in a moving target. They don't measure range. If frequency modulation is introduced, range can be measured.
With interrupted CW, the idea is that a missile doesn't need a continuous homing signal to generate an intercept course that will bring close enough to the target to put it within the blast radius of the missile's warhead. Remember, these missiles home using what is called proportional navigation. They are not line of sight homing, the guidance system calculates an intercept course to the target by trying to achieve a constant N value, the navigational constant in the proportional homing equation. Now, if this N value can be calculated from a less than continuous signal, say only 25% of the time, then the illuminator can provide a homing signal to other missiles. The number I quoted, four targets per illuminator, comes out of the 1981/82 edition of Combat Fleets of the World, in the US Navy section where the Aegis system is described. On the same pages the then proposed Burke Class DDG's are described.
Page 30 of this older document describes the principle of ICWI. This is how the AN/SPG-62 operates.

http://www.cbo.gov/ftpdocs/51xx/doc5175/doc15-Part4.pdf

This file from Raytheon describing ESSM supports this:

http://www.raytheon.com/capabilities...s01_055809.pdf

Now lets look at the geometry of an anti-ship missile attack. If a single DD fires four to eight missiles at a target, say a Sovremenny firing a half or full salvo at the notional CVN, all the missiles would originate from a very small point in space defined by the movement of the ship during the time between the launch of the first and last missile. The defending ship will see a stream raid of incoming missiles all on roughly the same azimuth. Some might go high, and some might stay low, but until terminal maneuvers are attempted. there will almost always be more than one missile on a single azimuth. The beam of the AN/SPG-62 can illuminate more than one missile under these circumstances. The maximum number depends on the geometry of the engagement and is apparently limited to four.
If you want to read further, there are documents on line describing the development of ESSM that mention having to change the guidance algorithms to accommodate ICWI and mid course inertial guidance when used with Aegis.

Ambivalent

Oh, by the way Wolvie, Thales is advertising it's latest ICWI having the ability to illuminate 32 targets similtaneously.
All of this becomes moot in about two years when SM-6 enters service with active terminal homing ( basically an AMRAAM seeker modified for the control algorithms of a Standard missile ).

Wolverine

OMG this is funny. Please explain to me how you did not just completely shoot yourself in the foot by providing this reference. Metaphorically speaking, this is more like blowing off your own head. Did you even really understand what p. 30 is saying?

(my bold)

This is EXACTLY what I just said in a previous post, and it is clearly in reference to the mechanically skewed SPG-62 that is CURRENTLY present on all Aegis warships. You clearly understand neither ICWI, nor agile beam steering, nor even the general principles of target illumination. Read further along that first reference. The capabilities of ICWI and agile beam steering are capabilities to be achieved on the DDX ("DDGX" in that reference), and only possible with ESA type radars. The relatively slow mechanical steering of the SPG-62 in comparison to what SPY-1, SPY-3 and APAR can do electronically means, as I already said, that there is no way in hell it can slew between 2 targets in a near continuous manner to allow for sufficient target illumination to occur, to speak nothing of 4. OTOH if that narrow illumination cone, which at "200kyd" range is actually about 3.1km in diameter (based on a 0.9 degree spread), encompasses more than 1 incoming missile, then that pencil beam will be illuminating multiple targets simultaneously, but certainly not because it has any kind of ability to employ ICWI by means of agile beam steering.

The fact that ESSM is compatible with both CWI (SPG-62 type radars) and ICWI (APAR, SPY-3, and other ESA's) is another shot in your own foot, and certainly does not in any way imply that the SPG-62 itself uses ICWI. In fact The Naval Institute Guide EXPLICITLY states that both the SPG-51 (p. 320) and the SPG-62 (p. 322) use CWI. You can't get more wrong than that kind of direct and authoritative contradiction of your claims.

That's right, Ambie. That's because it's an ESA, and they can do things like that.

LOL

crobato

That is correct. Pulse, CW, ICW, FMCW, forms are irrelevant to tracking ability.

A mechanical parabolic antenna, which only has a single point of focus, can only illuminate one single target at real time.

__________________
"Lets do a thermal sweep."

Ambivalent

Wolvie, the illuminator does not move physically between targets. The geometry of the targets has to be such that more than one falls inside the beam, which is a parabolic shape. Geometry is important, but in saturation attacks, or stream raids for a single azimuth, this is possible. The guidance signal is altered for each missile being directed. This was the first application of ICWI in operational use and was introduced with the Ticonderoga class.
ICWI capability was introduced to the Standard Missile family with RIM-66K-L, more often known as SM-2 Block IIIA. This is the Aegis variant that has been around for decades. Aegis uses ICWI for terminal guidance.

Raytheon’s Standard Missile Naval Defense Family (updated)

Wolverine

OMG I can't believe you are still arguing about this. You are so blatantly wrong it's getting more embarassing for you with every post and has all but completely shattered any credibility you may have had as some kind of military 'insider'. NOWHERE in that link does it state that Aegis uses ICWI for terminal guidance. It states that SM-2 Block III is capable of ICWI (just as the ESSM is), and it should be, because many countries which use the SM-2 have been moving toward ESA's, the only types of radars with this capability. The US itself will have this capability with the Dual Band Radar, specifically the X-band one. Your ridiculous refusal to accept the plain statement of your OWN source as well as the plain statement of the Naval Institute Guide now has you flying in the face of reality. Incidentally Googlebooks has the 5th edition online, so you can actually physically read the print yourself if you still want to front like you know what you're talking about. Here, let me help you:

The Naval Institute guide to world ... - Google Books

One more time, since it seems to be a slow process for you: only CWI illumination is possible for mechanically steered radars like the SPG-62 because it is physically incapable of the agile beam steering that is required to time-share 2 different targets and provide targeting information via ICWI. The SPY-1 actually tracks its targets via this method, but since it is S-band it is not capable of the resolution required to directly provide illumination for the SM-2, which is why it has to hand off target information over to the slaved X-band SPG-62 for terminal illumination. Other ESA's like the Dutch APAR, an X-band AESA radar, can provide both tracking and illumination for their SM-2's, and do not require any dedicated FCR's to do this. Consequently..... they don't have any on their ships.

Incidentally AESA's DON'T actually HAVE to use ICWI, but do so probably for reasons of efficiency. The reason is because AESA's can form multiple simultaneous independent beams assigned to different missions (volume search, surface search, low-speed tracking, high-speed tracking, low RCS tracking, illumination, etc.), whereas a PESA like the SPY-1 can only form one single beam (per panel) which is used to track hundreds of targets nearly simultaneously via a time-sharing manner. If the SPY-1 were X-band and intended to be used in both tracking and illumination, time-sharing (ICWI) is how it would illuminate its targets. Unfortunately for you, the SPY-1 hands off targeting data to the SPG-62, which is a mechanically skewed, CWI radar.

Ambivalent

Wolverine, ICWI capability in SM-2 pre-dates any shipboard AESA. It dates to the 1980's when SPY-1 was state of the art and no other navy had even a passive electronically scanned radar, much less an AESA.
Again, you do not need agile beam steering or an AESA to achieve the early form of ICWI used by AN/SPG-62. Yes, the geometry is very narrow, you have to have the incoming targets in the same fairly narrow beam, but the USN knew that in a saturation missile attack by the Soviets there was a very high probability this geometry would be realized. ICWI is achieved by using different freqs for each SM-2, and dividing the time assigned to each missile. The resulting information each SM-2 receives is adequate to get the missile close enough to the target ( sufficiently accurate N calculation ) that the target will be inside the blast radius of the SM-2's warhead.

crobato

There is no reason why you need ICW on the missile guidance itself. It is the main radar unit itself that needs it, and ICW is plainly redundant because you already have a pulse radar (SPY-1). Missile guidance doesn't rely on range information, it relies on unambiguous speed information which is provided already by CW.

The reason why APAR needs ICW---and it is the APAR that needs it, not the missile---is because APAR is not a pulse radar and therefore needs a system to obtain range. ICWI is intended to kill two birds with one stone---provide speed information for the missile guidance, while providing range information for the home radar set.

Having ICW on SPG-62 is possible but it is redundant and useless because SPY-1 is already a pulse radar and gets range info from the pulses. Putting ICW compatibility with SM-2 was intended for use from the beginning with non pulse search & tracking radars. AESA is not needed for ICW creation, but it still requires a specialized radar set with separate transmitters and receivers. If you put ICW on SPG-62, who is going to receive and process the range information? Not the missile itself, which only needs to recognize the signal, but not process the range information.

Again I repeat, ICWI is a shortcut between Pulse + CW. You don't need ICWI when you have already have pre-existing Pulse + CW sets. You want ICWI only when you consolidate two radar set functions into a single set, mainly tracking and illumination.

__________________
"Lets do a thermal sweep."

Wolverine

Ambivalent, you don't have ANY support of any kind for your now obviously fallacious claim that the SPG-62 is an ICWI illuminator. The main source that YOU yourself provided CONTRADICTS you. The Naval Institute Guide's section on the SPG-62 which I conveniently linked for you, CONTRADICTS you. BLUNTLY, might I add. At this point you have zero credibility and your pretense of insider military knowledge is all but completely shot. One rarely has evidence so unambiguous or so conclusive during internet debates, but this is very clearly a case where you are just dead wrong and yet have decided not to quit while you're behind.

It is physically impossible for a mechancally steered radar to achieve ICWI on even just two targets. The source that Ambie conveniently provided for SDF's benefit also CLEARLY states so, and it's not hard to see why. A mechanically steered radar would have to achieve spot targeting on two different targets nearly simultaneously, meaning it has to alternate between one target and the other over time intervals on the order of microseconds. This cannot be achieved by the SPG-62 or any other non-ESA radar. Only electronically steered radar beams have the agility to rapidly shift back and forth from one target to another to achieve an interrupted illumination that is still useful to an SARH missile homing in on the reflected radar beams.

Incidentally, the Naval Institute Guide also says APAR is a pulse radar. Not only that, you can also find this on Google. Here is an unambiguous statement that APAR is monopulse like the SPY-1, and like essentially every other ESA:

https://www.astron.nl/documents/conf...gy/tech03w.pdf

APAR doesn't use ICWI because it has to, it does so to increase the number of targets it can illuminate nearly simultaneously because the dwell time on each target is reduced with ICWI compared to CWI. A PESA illuminator, incidentally, would HAVE to use ICWI because as I said earlier the entire panel has only a single transmitter which is assigned to an entire quadrant of the sky. This transmitter would have to rapidly alternate between dozens to hundreds of targets in its quadrant to either track them or illuminate them. An AESA on the other hand could use CWI on many targets simultaneously because each panel contains thousands of individual transmitters which can then be further subgrouped by the computer and permanently assigned to different targets. Of course, this is wasteful since you don't need CWI on targets if your missile is capable of making due with ICWI. Actually theoretically each of the several thousand T/R modules on a given AESA panel could be individually and permanently assigned to a different target, though I'm certain there would be software/computing power limitations to such an approach.

Edit: I'm assuming a PESA with only a single TWT. PESA's with multiple TWT's controlling subgroups of transmitting elements on a PAR panel can result in a panel being able to send out multiple beams simultaneously, like an AESA. The PAC-3's radar for example is upgraded with an additional TWT compared to PAC-2, allowing an additional simultaneous beam to be generated for improved tracking and illumination. I reread the SPY-1D section in the Naval Institute Guide, and it looks like each of 4 panels on a Ticonderoga or Arleigh Burke has 8 transmitters, each controlling a subgroup of elements on a 4,096 element SPY-1D panel. Of course, each of these 8 transmitters on a side can track dozens of targets by time-sharing its beam over those targets, analogous to the way an ESA illuminator lights up multiple targets via ICWI.

crobato

Being an ICWI has nothing to do with the ability to steer multiple beams at once. An SPG-62 can in paper, send one beam of ICWI (which is possible for testing purposes to be used with a true ICW set on another end product), but SPG-69 can only send one beam. At the same time, an AESA can send multiple beams of CW. Being CW or ICW has nothing to do multiple beam scanning. Wave form and beam scanning are two unrelated issues. Being parabolic, cassegrain, inverse cassegrain, slotted planar, passive phase array, or AESA is also unrelated to being pulse, FMCW, ICW or CW. You can create an old school parabolic antenna and still use ICW.

Oh, APAR is not pulse. Its monopulse. Monopulse and pulse have different meanings. An ICW imitates the conditions of a pulse by creating an interruption in the CW. By monopulse it means it can take four angular readings within one signal, instead of having to send a signal each for each reading. Meaning it only takes one scan to determine its position rather than the antenna having to move back and forth and do multiple scans to get the position. Your posted article says APAR is a monopulse is correct. Even a CW transmitter and receiver can be a monopulse. But a monopulse does not mean its a pulse radar. Monopulse is just a scanning technique to obtain angular position; its really a different topic from pulse-CW-ICW-FMCW discussions. We discuss monopulse in the context with helical scan (where the antenna spins) and conical scan (where the antenna rotates).

People are arguing over different areas of radar technologies as if they are related when are in fact, unrelated.

__________________
"Lets do a thermal sweep."

Wolverine

Now you're starting to say the same thing Ambie is, which means both his source and Naval Institute Guide flatly and unambiguously say you're wrong. I don't know why the both of you keep talking like these sources either don't exist or have no weight compared to what you are posting, especially as neither of you have supporting sources to back yourselves up. The Naval Institute Guide flat out says that the SPG-62 is a CWI radar, and Ambie's source flat out says that Aegis illuminators are mechanical and employ CWI, and that they are too physically slow to employ ICWI. I believe too much "inertia" was the concept they were getting across.

And you're right about ICWI having nothing to do with multiple beams at once. I don't know what made you say that. I know I didn't say it. What I did say was that a PESA illuminator with only a single transmitter MUST use ICWI to illuminate mulitiple targets, and that an AESA illuminator CAN but does not HAVE TO use ICWI to illuminate multiple targets. I also said that mechanically steered illuminators CANNOT use ICWI, and this is supported by multiple sources, as I have stated multiple times.

You also seem to be confusing illumination with tracking, which are not equivalent concepts. ICWI is NOT "in between" CWI and pulse. Pulse has nothing to do with either ICWI or CWI. Illumination is just that, illumination. It neither provides any tracking information nor is the reflected illumination received or processed by the sending ship. All it does is paint the target for the SARH missile to home in on. Thus the SPG-62 provides the sending ship neither range, bearing, altitude or velocity, and it doesn't have to. Because that's not its job.

ICWI isn't pulsed or semi-pulsed, or pseudo-pulsed. ICWI is a CONTINUOUSLY emitted beam of radar that is rapidly cycled between different targets (which a mechanically steered radar is totally INCAPABLE of achieving). The "interrupted" part of it is not because the illuminator sends out beams in pulses, it's because the illumination is interrupted from the SARH missile's point of view in that it doesn't receive a constant paint on its target; instead it's like a sailor looking for a boat's progress by the light of a rotating lighthouse lamp, except that this lamp is able to light up the boat a few dozen times a second. This beam is CONTINUOUS from the lighthouse's point of view, not interrupted.

No, you can't. What you probably mean is that an old school parabolic antenna can be pulsed, which is correct. ICWI has nothing to do with pulsing. The 'interruption' in "Interrupted Continuous Wave Illumination" is not from the emitter's POV, it's from the homing SARH missile's POV. It's still continuous, meaning it's a flashlight that's on all the time, except that you are just rapidly flicking it between several different targets (ICWI). You are not rapidly turning it on and off as you cycle between those targets (pulse). It does not, and does not have to, provide any form of tracking information.

Oh, but it is. It is pulse and monopulse. Page 265 of the Naval Institute Guide says this about APAR:

You don't talk about pulsed repetition frequency with non-pulsed radars.

crobato

I don't care what guide you are using. ICW has nothing to do with antenna. That's the result of the backend circuitry and TWT. ICW can be produced by anything capable of phase and frequency modulation, which are actually old technologies dated back to the fifties. A mechanical antenna can produce ICW, the means to produce the ICW are separate from the antenna.


If its pulsed, its not continuous wave. If its continuous wave, its not pulsed.

Pulse radars cannot be illuminators, because pulses gives ambiguous speed readings. If APAR is used for end guidance illumination, then that end guidance illumination is continuous wave, albeit modulated, and therefore cannot be pulse. Another thing, the backend circuitry of pulse and CW are quite different, so a pulse radar cannot produce CW and a CW radar cannot produce pulse. Furthermore, a CW radar is also structurally different because a CW radar requires a separate receiver, while a pulse radar uses the same antenna for both reception and emission, dividing them into timed cycles.

Put to you in another way, pulse and CW are a contradiction.

If Naval Institute Guide is saying APAR is pulse, I believe they're flat out wrong.

I really think both of you don't know what Interrupted Continuous Wave is. Who told you it has something to do about being recycled rapidly between different targets?

The concept of ICW HAS NOTHING to do with targeting at all.

interrupted continuous wave definition of interrupted continuous wave in the Free Online Encyclopedia.

"A continuous wave that is interrupted at a constant audio-frequency rate high enough to give several interruptions for each keyed code dot. Abbreviated ICW."

In other words, you got a continuous wave that is being frequency and phase modulated to create regular interruptions. The reason for this interruptions is because you are getting your range readings based on those interruptions. Those range readings are used by the base radar set, not by the missile itself.

A mechanical parabolic like the SPG-69 has only one beam and can light one target, period. That beam is CW. Even if that beam is made ICW, it will still only light one target. The only purpose that ICW gives is to provide range information to a radar set, which the SPG-69 is not equipped with.

And no, it does not work like a lighthouse. Rather, something like APAR projects several beams at once. each beam lighting the target. It does not interrupt the beam to light one target at a time in time sharing fashion, as that is really no different from pulse and would give ambiguous readings. It also defeats the purpose of continuous wave as the reflection from the target is what is needed to be continuous, not from the source.

__________________
"Lets do a thermal sweep."

Wolverine

Clearly you know neither the noted expert Norman Friedman nor his 843 page Naval Institute Guide, the Bible of naval combat systems, a new edition of which appears every few years. We are now on the 5th edition. His writing gets as close to Final Word as open literature can get. Disagreeing with him is like disagreeing with Stephen Hawking on the details of quantum mechanics. Then there's you, a random internet poster. And I'm going to take your opinion over his? I think not. Not to mention you have no sources at all stating that the SPG-62 can employ ICWI. NONE. Not a single one. Or you would have produced it by now. I have two sources that say it's CWI, one of which is Norman Friedman himself, the other of which is provided, humorously enough, by Ambie. I could list more, but let's face it, I don't need any more. You on the other hand are just giving your incorrect opinion. You can continue to give your incorrect opinion in face of all reality and in the face of unambiguous and reliable evidence, and I suspect you will keep doing so, but that's all it will be. It doesn't matter how many times you say it or how many ways you say it. It would still be wrong.

No, it simply can't. See above. End of story.

That's right. So what? A pulsed beam is not a CW beam. That is self-evident.

Wrong. Pulse radars CAN be illuminators. RADARS CAN HAVE DIFFERENT MODES. This basic piece of knowledge is so basic that the fact that you do not know this does not bode well for your credibility. Aircraft radars for example, even the older pulse ones, have both CW and pulse functions. The AN/AWG-9 of the F-14 for example, can perform both TWS with pulse (for its Phoenixes) and illumination with CW (for its Sparrows). In fact it has many pulse modes. It has 2 TWTs, one assigned to CWI emission and one assigned to pulse emission.

AWG-9 Radar

Similarly, the APAR panel
Naval Institute Guide, p. 265

I have already demonstrated that you were incorrect in claiming that the APAR is not a pulse radar. Now I have also provided evidence that as a pulse radar it can provide terminal illumination, and that the two modes are not mutually exclusive in the same radar. Since we already have multiple other sources that states that APAR missile guidance is via ICWI, it is clear the APAR can both track by pulse and illuminate by ICWI.

Clearly your understanding of pulse and CW are in error, including all that stuff that you just said about hardware. The only hardware required is a TWT. The structure of the radar is unchanged. And actually, a CW illuminator like the SPG-62 doesn't need ANY receiver at all. It's an emitter pure and simple. The only thing that "receives" its emissions is the SM-2.

You can believe whatever you like, but you're still incorrect. If not, I invite you to provide a link which says that the same radar CANNOT emit both pulse and CW. In fact I invite you to provide links for all of those other claims that you have left unsupported so far and which are flat out contradicted by respected sources which I HAVE provided, like the claim that the SPG-62 can employ ICWI, that APAR is not a pulse radar, or that the physical structure of radars that emit CWI and those that emit pulses are different.

I really think you don't have the qualifications to make that statement.

No. This statement does not say that there is any ANY frequency or phase "modulation", rather that the signal is interrupted at a constant rate. This is your attempt to read your own misconception into this statement. And why does an illumination beam have any need of range readings, especially from a radar that is completely slaved to another radar that provides all the tracking information already, including range information? The answer is that it doesn't need range information, it doesn't do any pulsing of any kind, and it doesn't do any ICWI, which has nothing to do with ranging or pulsing.

Another unsupported claim. Provide a link that states ICWI provides any range information at all. Provide a link that states the SPG-69 can even be made ICWI.

Again, you do not understand ICWI. Let me repeat Ambie's source:

http://www.cbo.gov/ftpdocs/51xx/doc5175/doc15-Part4.pdf

This is lifted straight from the text. What does inertia have to do with pulsing? NOTHING. What does inertia have to do with ICWI? EVERYTHING. A mechanically steered radar like the SPG-62 cannot physically perform the rapid beam shifting from one target to another that "multi-targeting" ICWI requires, and is, again, something only an electronically steered, agile beam can accomplish.

It goes on to say this:
The meaning of these passages is clear enough. You are simply refusing to acknowledge the obvious conclusion that you do not have a correct understanding of what ICWI is.