Naval missile guidance thread - SAM systems

[Tam]

A monostatic radar on its own doing multitask , using the same antenna as transmitter and receiver.
Compared to this to use the antenna as a super high speed directional data transmitter and receiver is a trivial task..

View attachment 57657
The above mans that if the radar operator cut into half the aperture to use parts of it for communication, 4k movie download and so on then range of radar will decrease by square(2), the scanned surface to half, the scanned volume to quarter.

The aperture loss is more sever than the power loss.

So even if spiting the aperture trivial on the AESA, no sane operator will sacrifice the range of the radar .

And from communication standpoint, the whole aperture can communicate several magnitude faster and with way higher jam resistance than a small portion of it.

The radar being referred to isn't an AESA but a PESA, referring to the SPY-1 in particular, multitasking between communication and radar. That basically requires an all or nothing approach between going from radar to communication.

Anyway, my apologies to Max. The missiles do communicate with the array, and later Standard missile stocks have a dual S and X-band datalink that lets them work with AEGIS S-band and APAR X-band radars. The exact method isn't clear though it won't be the same the way an AESA would do it.

If the missile updates are only periodic and done only a few limited times, you can afford to split the aperture for a quick moment to send the communication. You can also afford to use the entire aperture just for that short moment.

 

[Anlsvrthng]

The radar being referred to isn't an AESA but a PESA, referring to the SPY-1 in particular, multitasking between communication and radar. That basically requires an all or nothing approach between going from radar to communication.

Anyway, my apologies to Max. The missiles do communicate with the array, and later Standard missile stocks have a dual S and X-band datalink that lets them work with AEGIS S-band and APAR X-band radars. The exact method isn't clear though it won't be the same the way an AESA would do it.

If the missile updates are only periodic and done only a few limited times, you can afford to split the aperture for a quick moment to send the communication. You can also afford to use the entire aperture just for that short moment.

It doesn't matter if it is AESA or PESA.

Say the radar has 400 MHz bandwith , that is at least 400 mbyte/sec.
Say the radar transmit 1000 pulse / sec.
Say the duty is 10%, so each pulse is 100 microsec.
After that the radar in receiver mode for 900 microsec.
Now, if the radar transmit instructions to the missile then it can choose to stop to transmit for 1000 microsec , and make 10 , 100 microsec command to the missile direction.

IT will be very high power, narrow beam, steered like the radar.

Each command can be 4 kbyte, if the data throughput is 400 mbyte/sec .


However I think a radar can afford to push out way more data, it is the data rate of a standard, consumer grade radio transmitter with a cheap sdr receiver.


If the missile transmit back data then the radar can switch to listening mode, and mop up the very weak signal of the missile, doing the hard work with the extremely big aperture.


If the radar is a dedicated tracking , and not in search mode then the equations are different, the duty cycle higher (up to 50%), and the radar can track lot of target AND doing the missile command / data receiving .

Say the radar doing 50% of the time tracking, and the leftover time communication, with 200 mbyte up/down combined bandwidth .

Regardless of the type, PESA, AESA is the same.

The main difference between the two is the manufacturing of PESA needs skilled, highly trained operators/technicians , and the manufacturer can not fire them if there is a gap in the government orders, and they cost way more .


The above equation is the reason why the SPY-1 needs active radar homing missiles, the S band search/tracking/illumination ect. radar hasn't got enough time to do all job that the S-300 doing with (at least) 3 different radar.

It boiling down affordability , the USA said that the NAVY doesn't have money for multi band radars, so they bought that they can, and to compensate the lack of funds they have to buy expensive munition.

 

[Max Demian]

The above equation is the reason why the SPY-1 needs active radar homing missiles, the S band search/tracking/illumination ect. radar hasn't got enough time to do all job that the S-300 doing with (at least) 3 different radar.

It boiling down affordability , the USA said that the NAVY doesn't have money for multi band radars, so they bought that they can, and to compensate the lack of funds they have to buy expensive munition.

Your post made perfect sense until the conclusion. SPY-1 was designed to counter saturation attacks at a time when the Standard missiles did not have ARH capability. Maybe the saturation threshold was lower back then, but the original design went with SARH missiles and dedicated end game illuminators. AEGIS and SM-2 have secondary midcourse guidance capability via the X-band 2T uplinks. In the 2T mode the missiles use their INS to fly to communicated PIPs and SPY-1 does not track the missiles. The downside is that the terminal mode needs to be engaged earlier compared to AEGIS due to larger uncertainty in the missile position.

Finally, I think even the MBR version of Flight III retains the dedicated X-band illuminators. Perhaps the improved capability of SPY-6 (+20dB) was sufficient to meet the new firepower requirements?

 

[Anlsvrthng]

Your post made perfect sense until the conclusion. SPY-1 was designed to counter saturation attacks at a time when the Standard missiles did not have ARH capability. Maybe the saturation threshold was lower back then, but the original design went with SARH missiles and dedicated end game illuminators. AEGIS and SM-2 have secondary midcourse guidance capability via the X-band 2T uplinks. In the 2T mode the missiles use their INS to fly to communicated PIPs and SPY-1 does not track the missiles. The downside is that the terminal mode needs to be engaged earlier compared to AEGIS due to larger uncertainty in the missile position.

Finally, I think even the MBR version of Flight III retains the dedicated X-band illuminators. Perhaps the improved capability of SPY-6 (+20dB) was sufficient to meet the new firepower requirements?

The Burke class has only 4 pcs of mechanically steered X band illumination, so any saturation attack it designed against can't have more than 4 incoming missile.

So to have more missile in the air than 4 they need active radar homing.

It going back to the cost vs capability decisions about the design of the Burke class.
And that going back to the Ticonderoga class, that has only 4 missile launcher .

So as later the number of expected incoming missiles increased the need for the ARH missiles born .

 

[Max Demian]

The Burke class has only 4 pcs of mechanically steered X band illumination, so any saturation attack it designed against can't have more than 4 incoming missile.

So to have more missile in the air than 4 they need active radar homing.

It going back to the cost vs capability decisions about the design of the Burke class.
And that going back to the Ticonderoga class, that has only 4 missile launcher .

So as later the number of expected incoming missiles increased the need for the ARH missiles born .

Hmm. The Burkes carry 3 mechanically steered X-band illuminators. Ticonderogas have 4.

SM-2 SARH in AEGIS mode is command guided almost all the way to the target. The X-band illuminators are needed for just the last few seconds in the endgame. What the limit of the system in terms of engaged targets is, is classified, but it is certainly more than 3
The number of in flight missiles should not be limited by the number of illuminators, but rather by the capability of the fire control system to guide them to targets.

But I get your point. Superior firepower (in excess of original AEGIS requirements) can be achieved with autonomous missile endgame guidance ( ARH or IR) or a dedicated MFR X-band ESA, like SPY-3 or APAR.

 

[Max Demian]

Curiously, the MBR equipped Flight III Burke appears to retain the mechanical illuminators.

Source:

Please, Log in or Register to view URLs content!

 

[Anlsvrthng]

Hmm. The Burkes carry 3 mechanically steered X-band illuminators. Ticonderogas have 4.

SM-2 SARH in AEGIS mode is command guided almost all the way to the target. The X-band illuminators are needed for just the last few seconds in the endgame. What the limit of the system in terms of engaged targets is, is classified, but it is certainly more than 3
The number of in flight missiles should not be limited by the number of illuminators, but rather by the capability of the fire control system to guide them to targets.

But I get your point. Superior firepower (in excess of original AEGIS requirements) can be achieved with autonomous missile endgame guidance ( ARH or IR) or a dedicated MFR X-band ESA, like SPY-3 or APAR.

Sorry , you are right, there is only 3 on the Burke.

The design of the Burkes still retaining of the Ticonderogas , only replacing the original missile system with vertical launchers.

The system configuration hasn't changed in the past 40 years ,only the missiles replaced, and the mains S band radar improved, but the design is the same - the re-evaluation and improvement of the system design started only now.

The mechanical illuminators has serious restriction about the targets engaged at the same time, and about the maximum usable distance.
An 10 000 elements ESA radar superior in range , number of targets illuminated at the same time, in bidirectional data throughput ,and provide endgame for more missile at the same time.

 

[Tam]

It doesn't matter if it is AESA or PESA.

Say the radar has 400 MHz bandwith , that is at least 400 mbyte/sec.
Say the radar transmit 1000 pulse / sec.
Say the duty is 10%, so each pulse is 100 microsec.
After that the radar in receiver mode for 900 microsec.
Now, if the radar transmit instructions to the missile then it can choose to stop to transmit for 1000 microsec , and make 10 , 100 microsec command to the missile direction.

IT will be very high power, narrow beam, steered like the radar.

Each command can be 4 kbyte, if the data throughput is 400 mbyte/sec .


However I think a radar can afford to push out way more data, it is the data rate of a standard, consumer grade radio transmitter with a cheap sdr receiver.


If the missile transmit back data then the radar can switch to listening mode, and mop up the very weak signal of the missile, doing the hard work with the extremely big aperture.


If the radar is a dedicated tracking , and not in search mode then the equations are different, the duty cycle higher (up to 50%), and the radar can track lot of target AND doing the missile command / data receiving .

Say the radar doing 50% of the time tracking, and the leftover time communication, with 200 mbyte up/down combined bandwidth .

Regardless of the type, PESA, AESA is the same.

The main difference between the two is the manufacturing of PESA needs skilled, highly trained operators/technicians , and the manufacturer can not fire them if there is a gap in the government orders, and they cost way more .


The above equation is the reason why the SPY-1 needs active radar homing missiles, the S band search/tracking/illumination ect. radar hasn't got enough time to do all job that the S-300 doing with (at least) 3 different radar.

It boiling down affordability , the USA said that the NAVY doesn't have money for multi band radars, so they bought that they can, and to compensate the lack of funds they have to buy expensive munition.

PESA with Yttrium shifters like SPY-1 have a dead time. During this period, antenna cannot receive or transmit. Dead time is when the shifters are reset to prepare for the next transmission. After transmit, a large part of the time between transmit and receive are placed into dead time. So the window of receive time during the pulse interval is small.

SPY-1B has a cycle time of 6.4, 12.7, 25 and 51 microseconds. If you transmit 10 microsecond packet within the receive time of the pulse interval, you are sending out when the echo is coming in. This results in interference in both the transmitted message and on the incoming echo. You would have to split aperture during receive, where for example, 90% of the elements are set in receive, and 10% of the elements or the number of elements equal to one subarray, would be transmitting the datalink signal.

 

[Tam]

Curiously, the MBR equipped Flight III Burke appears to retain the mechanical illuminators.

Source:

Please, Log in or Register to view URLs content!

View attachment 57659

That's already explained in previous post. The MBR is supplied with S-band by the SPY-6 and the X-band by SPQ-9B radar. SPQ-9B is a air and surface search and gunnery fire control radar only, and this is a small PESA that is placed high on the mast to detect sea skimmers. This radar isn't designed to provide missile target illumination. With SPQ-9B being a stopgap, Its possible the next generation X-band AESA won't bother with any CWI illumination mode. Saves money that way in terms of development cost and time. Your Standard and ESSM will be of the block that uses ARH, and SPG-62 is only kept for older missiles, gradually decreasing as they are in inventory as they are expended or expired. Again, just because you have X-band radar does not presume that the X-band radar is capable of SARH target illumination.

SPY-3 should note, is capable of missile target illumination and does that on the Gerald Ford, using ESSM for firing trials. However future Ford class would eliminate it both it and SPY-4, in favor of SPY-6 and using SPQ-9B, and should use ESSM Block 2 with the ARH seekers. Despite being an AESA, SPY-3 appears to be in a dead end, is being skipped, and intended to be replaced by a next generation X-band AESA (SPY-5?). They're not even bothering to currently pair SPY-3 with SPY-6 for a DBR, and choosing to use the cheaper and older SPQ-9B. Maybe its all for cost reasons.

An X-band radar of that size in the illustration would cost like hell and would require a very huge number of elements. In a more practical design, the X-band would have to be much smaller.

 

[Tam]

The C in C-band stands for "compromise". As you answered your own question , it enables a MFR with search/track/engage capability.

Concerning target engagement. As you pointed out, TVM is not without advantages. It is a multistatic radar system. The fire control system gets to process two reflections from the target: I suspect this is enough to overcome the weaker angular resolution compared to X-band.

Coming back to the question of Type 346 and HHQ-9.

The fact that everything points to HHQ-9 being derived from HQ-9, a C-band TVM guided missile, is what led me hypothesize that HHQ-9 introduced on Type 052C maintained the same guidance system. This would most elegantly be supported by a MFR radar with search/track/engage and TVM missile quidance, just like what is provided by Patriot and HQ-9 SAM systems from which it is ostensibly derived. Let's call this hypothesis A.

As far as I know, there is no shot of the Type 346 phase array. There is however that of the Type 346A on 052D, showing two narrow strips at the upper and lower edge of the array.

One hypothesis is that these are C-band arrays sandwiched around the central S-band array. Given their geometry, it is unlikely that these would serve an illumination purpose. Rather, it seems that they may be used for high data rate communication with HHQ-9s. This would be consistent with TVM. But in absence of any other candidate for an illumination radar we are lead to conclude that HHQ-9s on 052D must have some form of autonomous guidance in the terminal phase. Let's call this hypothesis B1.

Another hypothesis is that the two strips are an extension of the same S-band array. The communication with the missiles would then be carried out in S-band, like it is on SPY-1. Or that function may be fulfilled by the antennae that sit on top of the superstructure, above the Type 346 panels. Let's call this hypothesis B2.

In either of hypothesis B, the HHQ-9s have autonomous terminal guidance. This could be ARH or IR.

Lets go back to this again, in particular if the communication strip on the Type 346 is a C-band, which therefore, the HQ-9 communicates with the array via C-band.

By the time you get to the Type 346A, the array is now perfectly symmetrical, and there is no strip on the bottom. This means either two things:

A.) The HHQ-9 is now communicating with the Type 346A array directly, using the S-band. This means the new batch of HHQ-9 for the 052D destroyer uses an S-band datalink, or a dual S and C-band datalink, with the C-band for use with the 052C destroyers.

B.) The Type 346A has dedicated communication arrays, with their own independent transmitters and frequency band set along the corners of the Type 346A array. This means these corner arrays work on C-band and the HHQ-9 still communicates on C-band.

In order to prove or disprove one or the other, you need to have a photo of the Type 346A array itself without its cover, a kind of picture that has never been publicly available for years however.