PLAN Type 052C/052D Class Destroyers

Discussion in 'Navy' started by Jeff Head, Mar 14, 2014.

  1. taxiya
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    taxiya Major
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    They really don't. From this link that you posted earlier https://mostlymissiledefense.com/20...-defense-the-aegis-spy-1-radar-august-3-2012/, I quote
    The author suspected that loss. That loss includes "insertion loss" introduced by the phase shifter, plus any other loss due to the wires or wave guides in between. The actual insertion loss of SPY-1B (Lockheed Martin 2006) according to this report "Total Ownership Cost Reduction Case Study:AEGIS Radar Phase Shifters" (PDF file) by USN, is from -1.45 to -1.35 dB which is 77% to 71% loss. If the 77kw figure is right, and is the transmitter power as the quote above, that means less than 58kw to 59kw is emitted out from the antenna.

    When talking about AESA, the transmitter is the antenna, nothing between it and the space, so what ever number is listed is the power emitted. And that 125kw even if true, is from 1990s, while the number of SPY-1B is 2006.
     
  2. taxiya
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    taxiya Major
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    Don't play dumb.

    Wiki is mostly accurate IF and WHEN the article and subject does NOT involve Country/People's pride, that is when the subject is about pure science, such as PHASE ARRAY.

    On the other hand, subject involving countries are full of BS, and constantly being updated by rival users. Such as subject of tech from some are constantly being down played to the ground while others are bloated to the sky.
     
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  3. taxiya
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    taxiya Major
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    continue from #3101
    Another factor of loss vs. performance of SPY-1 and PESA in general is number of bits of the phase shifter. The more bits the narrower beam (smaller sidelobe). SPY-1B uses 4-bits as a compromise between loss and performance. This 4-bits is the base of the quoted insertion loss.
    On the other hand AESA does not use phase shifter, the beam is digitally coded and stored in a chip (digital beam forming), number of bits is not a compromise.
     
  4. Tam
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    Tam Senior Member
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    Scaffolding around the Kunming indicates work on the mast and the main radars. How will a maintenance refit, or update go with an 052D, compared to a potential mid life update?

    Update and maintenance
    1. Software and back end updates.
    2. Replacement of failed or worn out modules in the radar's face, or minor version change.
    3. Replacement and update on ESM, ECM, navigation, and communications equipment.

    I think what's happening on the Kunming, which so happens to be the first of the 052Ds, is the above, not the below. The Liaoning underwent its own recently. In this scenario, the ship will only be berthed for months, not years.

    MLU is going to be a much more severe and radical update. For now this is going to be hard to imagine on the 052D, unless we finally see an 052E to see where the direction of the changes are going. Such radical changes include:
    1. Complete change of the radars or major version change. Switching from the GaAs based to a GaN based radar for example. Replacement of the legacy mechanical radars to AESA as another example as the 052D still has a number of them.
    2. Change in armament, like the railgun although that may require boosting the ship's available power, which would require upgrading the ship's electrical generation and infrastructure.

    MLU is typically reserved for projects like the complete refit of the 053H3, the 052, the 051B and the Sovs, and what might be happening to the 054 frigates, as we have seen with the 525 Ma'anshan, completely stripped down of the old to make way for the new. Some 'dream' changes may not be implemented however, due to reasons of cost effectiveness, or reasons of ship balance, weight, electrical infrastructure, etc,.. It may involve years and virtually transforms the ship.
     
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  5. Max Demian
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    Max Demian Junior Member
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    Thanks for linking the article. I'm going to read it in more detail over the weekend. However, just by glancing through, I see that you have the bit number wrong. Per article, the 4 bit figure is for the original SPY-1A. The subsequent SPY-1B uses 6 bits. Increasing the number of phase shifters increased the insertion loss but improved the antenna gain (sidelobe performance) over the SPY-1A.

    Can you clarify your statement about AESA's not using phase shifters? This is the first time I hear this.

    I thought you meant that the phase shifters are replaced by true time delays? But that's not necessarily a property of AESA radars.
     
  6. Max Demian
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    Max Demian Junior Member
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    A few paragraphs before, you will find this:
    "
    According to a 2004 Defense Science Board Report, “the average radiated power aperture for the Aegis System is 485 kwm2.”[19] Assuming that statement applies to the SPY-1D (since the SPY-1D(V) version was not yet operational) and an antenna area of 12 m2, this would give an average emitted power of about 40 kW. "

    Multiplying that by 1.3 gives an imputed average radiated power of 53.2 kW per face for SPY-1D(V). However, the instantaneous power per pulse can be much higher that this, given that the combined amplifier power reaches 6MW. Of course, there are system losses until that power gets converted to radiated RF. I wouldn't hazard to guess what they amount to.

    For long range detection with low duty cycles, like ABMD, the power per pulse is quite important. That's one domain where vacuum tube powered ESAs still have an edge over solid state powered ESAs. That might explain why the US Navy decided not to replace the SPY-1D with AESA until high power GaN antennas matured.

    This Quora page has some answers on the topic: https://www.quora.com/Why-do-solid-...d-PESA-radars-like-SPY-1-and-does-that-matter

    I am not sure about that. I guess it depends on semantics. Yes, the antenna is part of the T/R element, but so is the power amplifier. From this article: http://www.ausairpower.net/aesa-intro.html
    "The first item of interest is power dissipation. Due to the behaviour of microwave transistor amplifiers, the power efficiency of a TR module transmitter is typically less than 45%. As a result, an AESA will dissipate a lot of heat which must be extracted to prevent the transmitter chips becoming molten pools of Gallium Arsenide - reliability of GaAs MMIC chips improves the cooler they are run. Traditional air cooling used in most established avionic hardware is ill suited to the high packaging density of an AESA, as a result of which modern AESAs are liquid cooled."

    All the numbers in the Wiki article on type 346 are to be taken with a grain of salt. We should compare the 25W peak power per element to other 2000s generation solid-state AESAs. Right now I don't have any sources for comparison, but would appreciate if someone does.
     
    #3106 Max Demian, Mar 14, 2019
    Last edited: Mar 14, 2019
  7. taxiya
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    taxiya Major
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    You are right regarding the bits. I was too quick reading it.

    I was not totally right on the phase shifter. AESA can be using either analog or digital beamforming. In analog beamforming AESA such as AN/APG-77, phase shifter is used on each T/R element. In digital beamforming, different phase of each element is pre-coded and fed to each T/R element.

    PESA has to use analog beamforming, as in SPY-1s. As we don't know any details about Type 346 except it is AESA, one can not tell for sure. I was not careful with my post.

    Here is a article I find, see page two. http://www.mptcorp.com/uploads/2/6/...igitalbeamforming_genericforpublicrelease.pdf
     
  8. taxiya
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    taxiya Major
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    It is indeed "semantics". Efficiency has to be strictly defined as what and where is the input, assuming the output is the power out to space. Since different implementations have different blocks, it is almost impossible to draw a fair comparison.

    Actually, IMO, the advantage of digital beamforming AESA over analog beamforming AESA over PESA is not much about raw output power, but rather the simplicity in realizing certain favourable tasks that is impossible for PESA, for example, freedom of creating multiple beams aiming at different directions simultaneously for multiple target tracking, or switching beam direction almost instantaneously (digital beamforming vs. analog regardless PESA or AESA).

    PS. the 45% figure is a surprise to me, but I can not say anything about it as I only know the theory but not the detail of semiconductor performance.
     
  9. Max Demian
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    Max Demian Junior Member
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    Continuing post #3106

    I did a bit more digging about solid state T/R element peak powers. This article goes into great details about X-band AESA radar T/R elements; https://mostlymissiledefense.com/20...e-defense-power-of-x-band-radars-june-4-2012/

    It would appear that in the early to mid 2000s, the state-of-the-art for X-band was about 10w peak power per TR element, and about 2w average power. Third generation in late 2000s has reportedly 16w peak power, as featured in the AN/TPY-2 radar.

    There are a few figures at the end of the article. One (fig 8) shows scaling of phased array radar element power as function of frequency and implementation technology, for 2007 state-of-art. Resolution is kind of crap, so it's not easy to tell what the ratio is for S-band to X-band. Looks something on the order of 2x or 3x more per element?
     
  10. Tam
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    Tam Senior Member
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    Actually they tried, with the SPY-3 and SPY-4 radars, intended for a new generation of warships, the CG(X) and the DD(X), Zumwalt, Ford class. Then they ran into issues, including both the radars. Then the quick advent of GaN made both radars obsolete. One has to consider the long list of advantages an AESA has, over one potential advantage that a PESA might have. If you look at many of these long range OTH stealth detecting radars, they are UHF and VHF AESAs. And not just that, but also radars used on AEW aircraft.

    High power per pulse is just a great way to be detected by ESM, also known as passive or covert radars, which can even obtain your ship's position to allow for a long range OTH antiship missile attack. You have to prefer detection using the lowest possible power to allow for LPI, or to make your own radar less detectable. Hence sensitivity is really what you are after with GaN.

    With an AESA, you can modulate the waveform to "peak" and create a similar phenomenon as a high power pulse. Furthermore, the agility of AESA can make the waveform look pseudo random that it can be construed as static, and not trigger off threat ESM.

    Range determines the length of your duty cycle, since you have to wait for the echo before you can transmit again, which is determined by the time it takes to travel by the speed of light / 2, and no less. So for long range you cannot have short PRF anyway, and short PRF will not allow for long range.

    Another thing that favors AESAs is that they work with pulse doppler techniques. With PESA, the shifters have to be reset after each transmission and that somehow affects creates noise that affects the use of pulse doppler techniques. That is why for so long, fighter jets use slotted array antennas, that these radars become synonymous with Pulse Doppler, and which is why, it is preferable to bypass PESA and straight into AESA for the next generation of fighter radars. For PESA you would have to use MTD to detect moving targets.

    Then because of the central transmitter, only two of the four array faces can be used to beam simultaneously (from the sources you quoted). In contrast the AESA can light up all four faces, even have different frequencies among them, or even across the face. With a PESA, all the four arrays will have to be of the same frequency and pulse.

    One thing for sure about the wiki articles, is that the Type 346 arrays would have to use S-band due to their size. If you were to using C-band elements, the number of elements needed to cover such an area may hit over 10,000, far more than the SPY-1's 4500 elements or the MPQ-53's over 5,000. And each of those C-band elements are AESA. You are going to run into issues with the sheer cost of each array and how you can cool those things.
     
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