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052C/052D Class Destroyers
- Thread starter Jeff Head
- Start date
Yeah the graph is wrong, I thought it was transmit frequencies, not elements.
Please, go ahead, define the difference between AESA and PESA for us then?
Have you taken a physics course before? Amplifiers simply apply gain to a system, they can't magically output a different frequency. Literally 1 page down from your source:
"For example, APL identified a way to reduce the number of transmitters from four to two, while maintaining performance, by developing high-power wave-guide switch technology that allowed a single transmitter to be time-shared between two arrays."
Please, go ahead, define the difference between AESA and PESA for us then?
Have you taken a physics course before? Amplifiers simply apply gain to a system, they can't magically output a different frequency. Literally 1 page down from your source:
"For example, APL identified a way to reduce the number of transmitters from four to two, while maintaining performance, by developing high-power wave-guide switch technology that allowed a single transmitter to be time-shared between two arrays."
I don’t remember talking about the South China Sea and DF-17. Just for the sake of argument. AN/TPY-2 has a range of 2000+ km vs ballistic missiles. If placed in southern Taiwan, it can easily cover the Paracel and Spratly islands. Or gaze as deep as Chengdu into China.
Then there's the floating SBX radar. Or the Cobra King onboard USNS Howard O. Lorenzen.
However, all of the above is irrelevant to the discussion about 052D.
This is not the right thread for this kind of discussion. There is a thread about Naval misille guidance theory that goes into lots of detail on this topic: Naval missile guidance thread
A picture I extracted from the thread, nicely highlighting the main difference between AESA/PESA
Key difference is the location of the HPAs and LNAs. Also note that in above picture, both PESA and AESA have one receiver/exciter. Therefore, both would be able to transmit at only one frequency simultaneously. So yes, such an AESA is possible.
Yes, I took the course. However, I don't remember saying anything about amplifiers outputting different frequencies. Transmitter != amplifier. A transmitter consists of a high power and low power sections. The lower power transmit section is responsible for waveform generation:
Yes, so? The original SPY-1A had 8 transmitters. Admittedly, I extrapolated from there the capability to transmit at 8 different frequencies. I don't have proof for that. Actually, I still struggle to understand why that would be so critical.
Perhaps you would be so kind to finally explain what is gained by concurrent radiation at multiple frequencies, and why only an AESA is capable of that?
Here, another example of a PESA radar with multiple (12) transmitter groups:
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A lot of that range is traveling through empty space, not through an atmosphere.
If placed in southern Taiwan, there is a YJ-91 ARM with its name on it. You shine radar up high, there is bound to have some reflection down due to the backscatter from the ionosphere. That's going to be picked up by ESM/EW assets. That's a large flashlight that is saying 'shoot me'.
Actually you brought up the whole suggestion about the need for ever larger or more powerful radars for future proofing. This is kind of ironic that if you had assumed that the 052D was using C-band like you and CMANO supposed some time ago, an AESA this large with the density format of C-band elements would have resulted in an even more terrific amount of heat and power generation.
Granted, let's forget that. Given the ship has a whole bunch of other radars --- Type 517M, Type 366, Type 364, Type 344, Type 347, plus two navigation radars, while carrying a full EW package and a plethora of SATCOMs, this ship's power generation is in no way, slight. Its already unusual to have a ship weighing only 7000 to 8000 tons to have AESAs this large and still carry a whole bunch of other radars, EW and communication equipment, while packing 64 VLS that has a large cell size. Try to compare that with a similar sized warship in service today.
Finally, as for LPI, there is always that risk, that LPI won't be so LPI, if you can break it with a signal analyzing algorithm.
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So why did you bring up the amplifiers in your post? What contribution to the argument were you trying to make?
So the point is the SPY-1 doesn't have the ability to transmit at 8 frequencies simultaneously. You made a false statement, I refuted it, that is how arguments work.
By your very own slide a PESA is defined as SINGLE large transmitter, if a radar set has multiple transmitters it is no longer a true PESA system.
Concurrent radiation at multiple frequencies is how you make more than one beam to track more than one target at a time without flickering between them. A PESA cannot do this since it has 1 transmitter.
I actually had to go back a few pages to see whether I actually said that or not. This is what I think you are referring to:
"Vacuum tube based PESA can actually fire shorter/narrower pulses than AESAs, which for technical reasons have much lower peak powers." This I said in response to:
AndrewS said:
Then you came and confused the ability to concurrently emit at multiple frequencies as having something to do with antenna gain.
I admitted that I don't have proof for that. To be honest, you didn't provide proof that it cannot do this. If each transmitter includes a waveform generator, then theoretically it should be able to do that.
I read somewhere before, that the early SPY-1 could emit only one beam at the same time, despite having 4 arrays (and 8 transmitters).
Even though I spelled it out for you, you still missed the key difference between PESA and AESA, because of your false preconceptions. What matters is where the HPA/LNA are located, not how many beams can be transmitted at the same time. Transmitting multiple beams lowers both antenna gain and transmit power. That may only be justified at close ranges. There is no technical hurdle for a PESA radar to do the same, if it has multiple waveform generators and HPAs controlling subarrays.
Cobra Dane is a PESA radar with 12 transmitters.
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If you are too thickheaded to see that as you add more and more sub-arrays and transmitters to a system you are effectively creating an AESA radar, I think we should discuss no longer as clearly neither of us has anything more to gain.
Nope.
I understand the 2 are distinct.
AESA simultaneously sending out many tighter beams at multiple frequencies results in better accuracy than using a single PESA frequency.
AESA also allows for more targets to be tracked at the same time.
PESA doesn't allow for this.
OK. Then explain this.
Assume we have two equal size phase arrays with a same number of elements. One AESA and one PESA. How can an AESA generate multiple beams (each of which is generated by a subset of array elements) which are tighter than a single beam emmited by PESA (generated by all array elements)?