PLAN Sovremenny DDG 136, 137, 138 & 139 Thread

[Tam]

I examined a bit more the various photos of the Top Plate radar and I think misjudged the size of the smaller antenna. From this angle the observed difference is much less:
View attachment 70400
So these must be the two 2 different S-band antennas: the smaller one at the lower frequency part of S-band and the bigger one at the upper frequency part of S-band. If Friedman is right, the smaller one is not a true 3D antenna, so it's still not a simple matter of multiplying the update rate by 2.

That's what I figured. Its using two different frequencies in the S-band range.

Its still a 3D antenna however as it is still frequency scanning on elevation. Its that obvious when you can see the snake shaped feed on the side of the array. So yes its still 3D, and regardless whether its 2D or 3D, you are still updating twice the tick in terms of the horizontal. 2D radars can still obtain elevation data via height multipathing, and radiating a stack of beams and determine which of these beams are reflected. With a planar array, elevation can be determined by the difference of the signals striking at different elements in the array and comparing the signals from each element. But in this case, the second array has S shaped frequency scan feeds, so that is definitely frequency scanning on the vertical.

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There are many frescans that are wider than they are taller. However, do note that beams are orthogonal from the array. So if the array is wide and short, the beam is turned around 90 degrees, and is taller than wide. So the beam produced here would be shaped like the array but turned around 90 degrees.





Addendum: I rechecked, Mk 26 should be firing the ASROCs.

Addendum 2: There are Soviet radars that are dual backed, but they are dual backed not because they are dual band, but because one array is active and the other is passive. Because of this, the "standard mechanical antenna" at the back may not be what it seems.

 

[nlalyst]

That's what I figured. Its using two different frequencies in the S-band range.

Its still a 3D antenna however as it is still frequency scanning on elevation. Its that obvious when you can see the snake shaped feed on the side of the array. So yes its still 3D, and regardless whether its 2D or 3D, you are still updating twice the tick in terms of the horizontal.

I think what Friedman was trying to say is that its 3D performance is inferior to the larger antenna, for two reasons:
- is much shorter in vertical dimension
- radiates at up to double the wavelength compared to the larger antenna
Two two combined, result in a significantly wider beam (vertically) and hence less resolution in elevation.

You don't have "three times" the range. SPG-51 is meant to engage up to the range of the Tartar missile, and that's only up to 30km

The Kee Lung class have the most up to date version (D) of the SPG-51. Compare that to the French Cassard class frigate which has 2 older SPG-51Cs and carries only SM-1 missiles. Even with that setup, the SM-1 MR can reach out to 46km. In the most pessimistic case, the Kee Lung would be limited to SM-1MR ranges with its organic capability.

The SPG-51D dish is slightly bigger than the SPG-62 on the AEGIS ships and has 4kW average power illumination vs 10kW for the SPG-62. For illumination, the SPG-62 would have about 50% more range for SARH missiles close to target. The main limitation would likely be the tracking range. However, SM-2 missiles can follow a designated sequence of setpoints purely on autopilot, but this results with greater uncertainty in their proximity to target in the endgame and requires turning the illumination on at an earlier point in time to give the missiles sufficient time to correct the deviation.

 

[Tam]

I think what Friedman was trying to say is that its 3D performance is inferior to the larger antenna, for two reasons:
- is much shorter in vertical dimension
- radiates at up to double the wavelength compared to the larger antenna
Two two combined, result in a significantly wider beam (vertically) and hence less resolution in elevation.


The Kee Lung class have the most up to date version (D) of the SPG-51. Compare that to the French Cassard class frigate which has 2 older SPG-51Cs and carries only SM-1 missiles. Even with that setup, the SM-1 MR can reach out to 46km. In the most pessimistic case, the Kee Lung would be limited to SM-1MR ranges with its organic capability.

The SPG-51D dish is slightly bigger than the SPG-62 on the AEGIS ships and has 4kW average power illumination vs 10kW for the SPG-62. For illumination, the SPG-62 would have about 50% more range for SARH missiles close to target. The main limitation would likely be the tracking range. However, SM-2 missiles can follow a designated sequence of setpoints purely on autopilot, but this results with greater uncertainty in their proximity to target in the endgame and requires turning the illumination on at an earlier point in time to give the missiles sufficient time to correct the deviation.

It does not look to me that it is shorter in the vertical dimension compared to other search radars, like say, the TRS-3D. Being shorter does not make it inferior in its 3D performance, you would need to count the number of vertical rows or elements, and having a slightly shorter band would increase the number of rows and the element density. There is no lack of either of those in the secondary array.

Having a higher frequency does not make its 3D performance inferior, rather it should improve it with better angular resolution and discrimination against clutter. It would be like higher res against the lower res on the SPS-48. It would also have better anti-clutter when scanning near the surface.

Friedman got wrong intel here straight out, as there is no Fregat in service that has S band in one side and X band in another. There might have been a proposal for one such, as there was a proposal for a dual S and H band, much like combining the older model with the array from the 4K model, but none of these were in sold or in service.

I won't call it pessimistic, but rather optimistic, when it comes to the engagement range, even if SM-2 is paired with SPG-51. If you're going to deal with antiship missiles which typically has an RCS below 0.5, its all going to be lower. SM-2 only changes the seeker from the SM-1 from a conical scan to a monopulse and slotted array, its still semi active and the source radar remains the same. Your gain is in ECM resistance. You're also comparing the average power of the C-band pulse doppler radar of the SPG-51 vs. the SPG-62, and that's two very different things, as the X-band illuminator on the SPG-51 is separate. So there are two separate beams. Range isn't important here, but its PK against antiship missiles.

When it comes to illumination, the MR90 Orekh works much differently. Instead of a C-band tracker with the X-band illuminator fixed to it, the unit is both tracking radar and illuminator at once. This means the very waveform it is using to track the target is the same as the one illuminating the target. For that it works on FMCW instead of a pure CW. That's in line with other Soviet SAM radars, and if it is in line with typical Soviet SAM radars, it may also feature a spaced phase array.

 

[nlalyst]

It does not look to me that it is shorter in the vertical dimension compared to other search radars, like say, the TRS-3D. Being shorter does not make it inferior in its 3D performance, you would need to count the number of vertical rows or elements, and having a slightly shorter band would increase the number of rows and the element density. There is no lack of either of those in the secondary array.

Inferiror compared to the the big array on Top Plate. It is has about 2/3 of the height and works on a lower frequency (higher wavelength). One reason he mentions for having the two arrays operate in two distinct frequency bands is to provide frequency diversity for ECCM (this was in reference to the Plate Steer).

Friedman got wrong intel here straight out, as there is no Fregat in service that has S band in one side and X band in another. There might have been a proposal for one such, as there was a proposal for a dual S and H band, much like combining the older model with the array from the 4K model, but none of these were in sold or in service.

I think he was quoting marketing material. For the single face variants of Fregat-MA, like the MAE-4K, he explicitly mentioned Abu Dhabi, 1993 as the source. But OK, this is slowly becoming ancient stuff by now.

I won't call it pessimistic, but rather optimistic, when it comes to the engagement range, even if SM-2 is paired with SPG-51. If you're going to deal with antiship missiles which typically has an RCS below 0.5, its all going to be lower. SM-2 only changes the seeker from the SM-1 from a conical scan to a monopulse and slotted array, its still semi active and the source radar remains the same. Your gain is in ECM resistance.

SM-2 also added automatic inertial navigation, which was a big thing back then. This way the missile can follow a designated path of setpoints even after the tracking radar can no longer "see" it. Because such a "blind" missile might increasingly deviate from target as time goes by, the terminal illumination needs to be started earlier compared to AEGIS which uses the SPY-1 to guide the missile until it is only a few seconds away from hitting the target.

You're also comparing the average power of the C-band pulse doppler radar of the SPG-51 vs. the SPG-62, and that's two very different things, as the X-band illuminator on the SPG-51 is separate. So there are two separate beams. Range isn't important here, but its PK against antiship missiles.

I was comparing only the X-band CWI components. The 4kW average power on SPG-51 is solely for the X-band CWI. The C-band tracking radar has a separate feed, but shares the same antenna.

The Mk 74 Mod 15 which was installed on the Kidds before they were transferred to ROC, has an addtional X-band CWAT (continuous wave acquisition and track) radar via a secondary antenna. Friedman included a photo of the setup in his book, but I cannot find it in photos available online. Wikipedia page for SPG-51 claims the same:

The MK 74 MOD 15 configuration includes

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tracking in addition to pulse-Doppler tracking. It provides illumination for

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operation associated with missile guidance in all configurations. Older systems rely on

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rather than monopulse.

 

[Tam]

Inferiror compared to the the big array on Top Plate. It is has about 2/3 of the height and works on a lower frequency (higher wavelength). One reason he mentions for having the two arrays operate in two distinct frequency bands is to provide frequency diversity for ECCM (this was in reference to the Plate Steer).

I think he was quoting marketing material. For the single face variants of Fregat-MA, like the MAE-4K, he explicitly mentioned Abu Dhabi, 1993 as the source. But OK, this is slowly becoming ancient stuff by now.

SM-2 also added automatic inertial navigation, which was a big thing back then. This way the missile can follow a designated path of setpoints even after the tracking radar can no longer "see" it. Because such a "blind" missile might increasingly deviate from target as time goes by, the terminal illumination needs to be started earlier compared to AEGIS which uses the SPY-1 to guide the missile until it is only a few seconds away from hitting the target.

I was comparing only the X-band CWI components. The 4kW average power on SPG-51 is solely for the X-band CWI. The C-band tracking radar has a separate feed, but shares the same antenna.

The Mk 74 Mod 15 which was installed on the Kidds before they were transferred to ROC, has an addtional X-band CWAT (continuous wave acquisition and track) radar via a secondary antenna. Friedman included a photo of the setup in his book, but I cannot find it in photos available online. Wikipedia page for SPG-51 claims the same:

You got it backwards. The bigger array on the Top Plate has the lower frequency and the smaller array has the higher frequency, as often arrays are because a lower frequency means a larger waveform requires proportional separation between the elements resulting in a bigger, less dense array. So bigger array, lower frequency, smaller array, higher frequency. Whatever is lost with the smaller array is gained back with the higher frequency. This has nothing to do with ECCM. The higher frequency is for less clutter for scanning flying targets near the water's surface. The use of two array faces and a higher frequency on one array face also improves on the track quality of the target. If we were to go with NATO instead of IEEE on the wave bands, one array on the Top Plate might be on E band and the other might be on F-band.

You can see from the picture below that the smaller array has a finer grate, with smaller but more rows. That's a higher frequency with less separation between the elements for a more dense array.

MAE-4K is still being marketed but has never found a buyer since it was offered. It has zero relevance when it comes to the Sovremenny as the ship never used this. See also below.

Even if inertial navigation is used, you need high quality track on the target, and against a high maneuvering target, automatic set point inertial navigation can quickly find its given path obsolete and can be far off from the target when it needs to go terminal. That's the same point you made. So you have to go terminal earlier and light up the target sooner. If the target receives an X-band CWI alert from its RWR, it will perform evasions and countermeasures, so your odds of PK gets lower. The target would already be in an alert state when it receives the C-band pulse so it knows its already under weapons quality track. This scheme of using an inertial navigation system sounds more effective in closer ranges than it is far.

The way the MR90 or any other Soviet SAM radar works, like Tombstone, is that it uses FMCW on TWS, and at this point, the target does not know if a missile is fired or not, only that a fire control radar has already illuminated it.

In addition to Top Plate, what the other two PLAN Sovremenny is using the Pozitiv ME radar at the rear. This is the X-band radar also used for surveillance and air defense. None of the Soviet or 'generic' Sovremenny have this radar.

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It has three different versions, and appears to be a phase array with frequency scanning.

I don't know if Friedman might be mixing this up.




While it is said to be meant for servicing the Kashtans, it might as well be servicing the MR90 Orekhs with weapon quality track and queuing them to their targets, leaving the Fregat free for search mode only. This will do a better job for anti-clutter in surface scanning with its X-band, so the dual band on the Fregat becomes moot. The advantage of using this over the Fregat for queuing the MR90s is because the Fregat might give a more loose track, and the MR90 will have to compensate with additional scans. If this is the queuing radar, the MR90s can be silent but already accurately aimed at the targets, and less time is needed for compensating for a faster reaction time against the target. The target itself will not be illuminated by the MR90s, but by this, which give an X-band pulse instead of a CW.

 

[Tam]

To add to the above, with regards to Top Steer vs. Top Plate on ECCM, the use of frequency scanning limits your frequency band options, and having a second array that's also frescan only doubles your limited options.





But with Top Steer, the other array isn't a frescan, but a parabolic. You get more frequency band options with this, and also includes the ability to use pulse compression which is not something the frescan can do.

 

[nlalyst]

You got it backwards. The bigger array on the Top Plate has the lower frequency and the smaller array has the higher frequency, as often arrays are because a lower frequency means a larger waveform requires proportional separation between the elements resulting in a bigger, less dense array. So bigger array, lower frequency, smaller array, higher frequency.

According to Friedman, it's the other way around. What's your source?

Even if inertial navigation is used, you need high quality track on the target, and against a high maneuvering target, automatic set point inertial navigation can quickly find its given path obsolete and can be far off from the target when it needs to go terminal. That's the same point you made. So you have to go terminal earlier and light up the target sooner. If the target receives an X-band CWI alert from its RWR, it will perform evasions and countermeasures, so your odds of PK gets lower. The target would already be in an alert state when it receives the C-band pulse so it knows its already under weapons quality track. This scheme of using an inertial navigation system sounds more effective in closer ranges than it is far.

Can't the same argument be made against aircraft launched ARH missiles? The relatively small and underpowered aircraft radars are unable to track the missiles as far out as ship-borne radars can, so the missiles have to rely on properly adjusted setpoints to arrive close enough so that the target falls within their homing basket.

A missile in mid-course could still receive updated setpoints, even if the tracking radar can no longer detect it, relying that the inertial guidance of the missile is good enough to figure out its position.

The way the MR90 or any other Soviet SAM radar works, like Tombstone, is that it uses FMCW on TWS, and at this point, the target does not know if a missile is fired or not, only that a fire control radar has already illuminated it.

Same could be said of other command guidance systems or TVMs.

You don't have "three times" the range. SPG-51 is meant to engage up to the range of the Tartar missile, and that's only up to 30km. ... That becomes a problem if your missile has a lower tail and mid section RCS, and the Standard is a much smaller missile than the Tartar. You can do this with SPY-1 because of the brute strength of the phase array, but not an oldie like the SPG-51 which is likely to be continuous wave illumination all the way from start to finish. Older Standards, pre-AEGIS work with continuous illumination all the way.

Not quite. The early Tartar and Terrier missiles were beamriders. They were upgraded to semi-active homers in the 1959/1960. Both missiles were upgraded to the Standard missile in mid 60s. Terrier became SM-1 ER and Tartar SM-1 MR. SM-1/SM-2 is not any smaller than Tartar. In fact, later variants are larger. Are you mixing up Tartar with Talos? Second, many missiles have a beacon emitter at their tail, so only a receiver would be needed onboard.

SPG-51 was installed on Virginia class nuclear cruisers, that were armed with SM-2 MRs. These missiles have a range of 90nm. Therefore, I think it's safe to assume that ROC's Kidd destoyers have the same capability, which gets us to about 3x the 956 EM that PLAN has.

 

[nlalyst]

I wanted to add, but ran out of time, that in addition to radar tracking corrections from the ship, the SAMs can also get GPS corrections. The benefit of GPS correction is that its velocity and position errors remain constant throughout flight, unlike the ship radar corrections whose errors increase the further away the missile is from the ship.

 

[Intrepid]

The benefit of GPS correction is that its velocity and position errors remain constant throughout flight ...

GPS signals can easily be disturbed or falsified. I think GPS will become a purely civilian peacetime-application.

 

[nlalyst]

GPS signals can easily be disturbed or falsified. I think GPS will become a purely civilian peacetime-application.

Yes, if the device has no anti-jamming capability.

Spatial Temporal techniques can be used to defeat jammers, by maximizing the signal level in the direction of the satellite and ignoring jammer interference from other directions. This is accomplished with digital beam-forming and digital processing techniques, like it was done with G-STAR for JASSM.