Naval missile guidance thread


Anlsvrthng

Senior Member
Registered Member
This is digital beamforming in the Ku band range, which is 12 to 18Ghz. You got digital beamformer in 8 FPGA serving a 256 element array.


It is NOT digital beamforming.
As simple as that.

And yes, the AESA vs PEASE is defined by the per element amplification of the signal.

By your definition if we swap the traweling wave tube on a PAC-1 to a solid state GaN amplifier network then it become AESA .
 

Anlsvrthng

Senior Member
Registered Member
The problem is that you are saying stuff without any technical reference in support of your assertions.

The main reason why the technology is still at sub array level currently and not at the element level is the enormous amount of digital processing needed. Digital beamforming is all about digital processing power.

The following AWST article written in 2015 is clear that the technology has progressed to the sub array level at that time based on the work by DARPA .



Source : Darpa’s ACT Program Digitizes Active Arrays. Mar 12, 2015
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| Aviation Week & Space Technology
My support is simply the math : )

With max 4-5GHz transistors how can you digitally generate at least 1/100 precision 10GHz signal ?

Answer : you can't. All that can be do is to generate the digital IF signal, and mix it onto the analogue carrier signal with analogue beam forming.
 

Brumby

Major
My support is simply the math : )

With max 4-5GHz transistors how can you digitally generate at least 1/100 precision 10GHz signal ?

Answer : you can't. All that can be do is to generate the digital IF signal, and mix it onto the analogue carrier signal with analogue beam forming.
So your whole argument is based on the limitation of your own knowledge on the subject.
 

Tam

Captain
Registered Member
It is NOT digital beamforming.
As simple as that.
Not according to the creators.

And yes, the AESA vs PEASE is defined by the per element amplification of the signal.
No its not. Find me a reference please.

By your definition if we swap the traweling wave tube on a PAC-1 to a solid state GaN amplifier network then it become AESA .
Bull. Nope. Complete depends on the location of the amplifier network.

If the Gan amplifiers are in a parallel cluster to form a single massive amplifier, and still situated underneath the optical feed, its would still be a PESA.

If the GaN amplifiers are set each set below a transmitting element, its becomes an AESA. The new radar for Patriot has its amps set inside the array itself with each element. The modules are like bricks.

unnamed (2).jpg

And you cannot swap a PAC-1 with an amplifier network because you don't seem to know sh*t what kind of a PESA type this is. You cannot do this because the amplifier is in the truck while the array is lifted up in the air.

mpq53.jpg

The array is really nothing but a lens consisting of phase shifters that act as refracting polarizing filter. There is a box on the back of the array that is an optical space feed that projects the radar signal to the back of the array, which then "lenses" the signal into a beam.

S-300 Flaplid and Tombstone works the same way. You can see the feed horn there extended. This type of PESA is common with SAM radars.

30N6E.jpg


Reflective Spaced Phase array principle. Here you see the feed facing down at the array so it can bounce the signals off from it. The array steers the beam via phase shifters that are polarizers.


S-300PMU2-Favorit-64N6E2-Big-Bird-VPVO-Deployed-2S.jpg
 

nlalyst

New Member
Registered Member
So your whole argument is based on the limitation of your own knowledge on the subject.
Perhaps then you would be so kind to explain to us how the digital beamforming at the sub-array level on the F-35 works?

The quotation from the 2015 article by Aviation Week had nothing in particular to say about the F-35. In fact, the following may be indicative of the state-of-the-art:
Some of the latest AESAs now in development are digital at the subarray level, but ACT is pushing the technology all the way to the array element.
If the technology was still in development in 2015 how did it find its way onto the F-35 already well into LRIP?
 

Tam

Captain
Registered Member
I'd say it's still pretty advanced compared against the early AESA systems of the late 1970s. However, the point was to demonstrate that radar
There isn't a lot of early AESA systems, and for the most part the foundation technology is lacking to make it successful. Case in point is this ship.

longbeach.jpg

First ship to have an AESA in the world. But the technological foundation at that time could not meet the ambition. So the radars were scrapped, the ship was converted to using an SPS-48 --- rotating scanning only in elevation PAR --- and lessons learned applied on SPY-1.

designers indeed did build AESA systems similar to that NXP design with analog beamforming. And the F-22 is still flying around, so we can't just ignore it because it's not the future.
There are two things facing the F-22 radar and whether other designs would follow it or not depends.

First, the radar is in uncharted territory. Someone has to do it, like that ship above. Being a pioneer, it may not be trouble free and the lessons learned will be applied to future radar systems and that will result in changes.

Second, the radar was built with the foundation technologies at that time. New systems are going to be built using the foundation technologies of this time. So if you design a system now, you use the technologies on hand, like FPGA, GaN, chip sized amps instead of brick sized amps. There is a huge difference between the techs available before the year 2000 and in 2020. There seems to be already a large gap between the radar systems of the F-22 vs. the F-35.

Sorry, but you brought the Telecom into the discussion. I showed you that indeed, they still do substantial analog processing/computing, besides the obvious front-end RF with tuners, switches, amplifiers and ADCs. An important advantage of analog beamforming over digital is that it is more energy efficient. Further efficiency can be gained by not doing the computation electronically, but optically. This makes sense in presence of substantial optical backbones. The SOWICI project of the Netherlands is an example of this.
Not going to argue this. Still the trend is going digital in order to handle larger volumes of connections. The importance of digital is low noise, even though analog offers high gain, low loss. In anything else below mmwave, its all moving to digital, and probably already all digital with L and S-band frequencies.

Yeah, but that's not a Digital Array Radar. Since the AMDR-S was advertised as a DAR, I think it is fair to assume that the AMDR-X (or is it SPY-5 now?) will be one too, once/if the technology is ready.
Are you sure they are aspiring to have digital beamforming per element rather than per array? The subdivision of MRAs or subarrays in the SPY-6 suggest to me that digital beamforming is in the subarray level. I don't see the point of them trying to go digital beamforming per element versus per subarray if they want to reduce cost, and with a more realistic delivery time. I get the feeling the USN is fed up with engineering experimentation and wants to rush less ambitious but affordable and working technologies into the front.
 

nlalyst

New Member
Registered Member
Are you sure they are aspiring to have digital beamforming per element rather than per array? The subdivision of MRAs or subarrays in the SPY-6 suggest to me that digital beamforming is in the subarray level. I don't see the point of them trying to go digital beamforming per element versus per subarray if they want to reduce cost, and with a more realistic delivery time. I get the feeling the USN is fed up with engineering experimentation and wants to rush less ambitious but affordable and working technologies into the front.
I am not sure. Perhaps there is digital beamforming at a subarray level. You then have analog beamforming closest to the antenna, and digital further away. But a subarray per RMA may be too simplistic, I think. That would reduce a 5500-6000 element radar to a 37 element digital radar, with the elements now separated far more than lambda/2 introducing grating lobes while scanning. They would have to be a bit more clever than that.

Promo video from Raytheon (with SM-6 taking out a 052D):

I liked the LockMart video on AMDR-S better. At least it had something educational about it.
 
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nlalyst

New Member
Registered Member
I get the feeling the USN is fed up with engineering experimentation and wants to rush less ambitious but affordable and working technologies into the front.
I wonder if that's actually the case here. Lockheed Martin lost the competition to Raytheon for AMDR-S way back in 2013. The first SPY-6 delivery is aimed for 2023. Clients are choosing LM's S-band SSR Aegis ashore architecture over SPY-6 on the grounds of the former being ready sooner. However, Raytheon's AMDR-S managed to significantly exceed the original requirement of +15dB in sensitivity over SPY-1. The latest claim is that it is +20dB more sensitive. Maybe that's what sold it to the Navy.
 

Brumby

Major
Perhaps then you would be so kind to explain to us how the digital beamforming at the sub-array level on the F-35 works?
Do you seriously think that LM would disclose proprietary information on the F-35?

The following is the technical reference that configuration exist at the sub array level with the F-35.
1584078094414.png

1584078159033.png

Source :
1584078185495.png

At least there is evidence to sufficiently debunked your view that it cannot possibly happen at the sub array level.
 

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