Naval missile guidance thread - SAM systems

[Anlsvrthng]

I try to simplify the question to Brunby and Tam.

These are my PMR446 radios.
Two identical.
What modifications I need to make on them to have a 2db amplification Tam defined phased array antenna ?
Two important point :
-it needs to be relatively cheap, so the cost of it can not be more than few thousand pounds/unit
-it needs to have small version, to fit the X band element of the AESA, the suggested modificatio doesn't need to be small however.



So, what I need to buy and how to install to have two independent, but perfectly phase aligned signal ?

 

[nlalyst]

Can be doesn't me They Do. Theoretical doesn't mean the Practical.

Go ahead and find me an AESA design that has long feed lines between the TRMs to the signal generators.

In reference to the above quote, you claimed that all AESAs come with an ADC in the module, because no radar designer would do something as stupid as not to put it there. On top of that, you also insist that there is a signal generator in the TRM. Despite the teaching slides and diagrams of an NXP radar design showing that there also exist analog AESA designs, that have none of the above in the TRMs, you still refuse to accept that because I haven't shown you an actual product that's built like this. How about this for an example:


Source:

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Oh, now you will say cannot be true. F-22 AESA analog !!?? Give me a signed letter from the CEO of Northrop Grumman or I don't believe it. ROFL.

Yes, Digital > Analog. Digital is binary, it is either 0 or 1. There is no distortion between the two. You honestly think that modern Telecom still uses any analog?

Why would I ever think that. Oh wait, except for the reason that's exactly what they are doing for 5G:


Source Qualcomm:

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The article Digital Beamforming Accelerates the Evolution to Next-Generation Radar, from Microwave Journal, dated 2017 had the following to say on the subject:
"It is desirable to eliminate the analog beamformer and produce an every-element digital beamforming system. With today’s technology, this is possible at L- and S-Band ... However, the quest remains to approach every-element digital beamforming, which places significant demands on the waveform generator and receivers ... Digital beamforming relies on the coherent addition of the distributed waveform generator and receiver channels, placing additional challenges on the synchronization of the many channels and system allocations of noise contributions."

Here is something you will like. The AMDR-S radar now known as AN/SPY-6 coming to a Flight III Burke near you is a Digital Array Radar with all the bells and whistles of a radar of that kind. A promo video from Lockheed Martin:

In light of the above quote, I think it is understandable why the new X-band radar for the Flight III is still under development.

 

[Anlsvrthng]

"It is desirable to eliminate the analog beamformer and produce an every-element digital beamforming system. With today’s technology, this is possible at L- and S-Band ... However, the quest remains to approach every-element digital beamforming, which places significant demands on the waveform generator and receivers ... Digital beamforming relies on the coherent addition of the distributed waveform generator and receiver channels, placing additional challenges on the synchronization of the many channels and system allocations of noise contributions."

And here is the problem , if the Intel can deliver the 7 GHz pentium in 2007, and the 200 GHz in 2020 then the X band digital beamforming would be easy job.

But the semiconductor technology can't make fast enough circuit. Bye bye SDR X band radar on the F-35.

 

[Brumby]

And here is the problem , if the Intel can deliver the 7 GHz pentium in 2007, and the 200 GHz in 2020 then the X band digital beamforming would be easy job.

But the semiconductor technology can't make fast enough circuit. Bye bye SDR X band radar on the F-35.

The F-35 to my knowledge is the only fighter platform with true digital beamforming capability - at sub array level. Such capability is provided by FGPAs and not GPUs. It is rumored that the F-35 uses six of it.

 

[Tam]

In reference to the above quote, you claimed that all AESAs come with an ADC in the module, because no radar designer would do something as stupid as not to put it there. On top of that, you also insist that there is a signal generator in the TRM. Despite the teaching slides and diagrams of an NXP radar design showing that there also exist analog AESA designs, that have none of the above in the TRMs, you still refuse to accept that because I haven't shown you an actual product that's built like this. How about this for an example:

View attachment 58246
Source:

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Oh, now you will say cannot be true. F-22 AESA analog !!?? Give me a signed letter from the CEO of Northrop Grumman or I don't believe it. ROFL.

F-22's AESA radar started development in the 1990s. By today's standards in AESA advancement, its already an antique.

Even those brick like AESA arrangements I have been showing you about is already getting old.

This is how the future looks like. Note the FPGA digital beamformers all arranged at the sides of the PCB that contains all the elements.

Why would I ever think that. Oh wait, except for the reason that's exactly what they are doing for 5G:

View attachment 58247
Source Qualcomm:

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You forgot to mark the entire sentence. Nice of you to take things out of context since you forgot about the path loss above 24Ghz.

Off the subject since you apparently don't know what is going on, and why analog beamforming is being used above 24Ghz.

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Digital beamforming (aka. Baseband beamforming, aka precoding)
The signal is pre-coded (amplitude and phase modifications) in baseband processing before RF transmission. Multiple beams (one per each user) can be formed simultaneously from the same set of antenna elements. In the context of LTE/5G, MU-MIMO equals to digital beamforming. Multiple TRX chains, one per each simultaneous MU-MIMO user, are needed in the base station. Digital beamforming (MU-MIMO) is used in LTE Advanced Pro (transmission modes 7,8, and 9) and in 5G NR. Digital beamforming improves the cell capacity as the same PRBs (frequency/time resources) can be used to transmit data simultaneously for multiple users.

Analog beamforming
The signal phases of individual antenna signals are adjusted in RF domain. Analog beamforming impacts the radiation pattern and gain of the antenna array, thus improves coverage. Unlike in digital beamforming, only one beam per set of antenna elements can be formed. The antenna gain boost provided by the analog beamforming overcomes partly the impact of high pathloss in mmWave. Therefore analog beamforming is considered mandatory for the mmWave frequency range 5G NR.

The article Digital Beamforming Accelerates the Evolution to Next-Generation Radar, from Microwave Journal, dated 2017 had the following to say on the subject:
"It is desirable to eliminate the analog beamformer and produce an every-element digital beamforming system. With today’s technology, this is possible at L- and S-Band ... However, the quest remains to approach every-element digital beamforming, which places significant demands on the waveform generator and receivers ... Digital beamforming relies on the coherent addition of the distributed waveform generator and receiver channels, placing additional challenges on the synchronization of the many channels and system allocations of noise contributions."

Here is something you will like. The AMDR-S radar now known as AN/SPY-6 coming to a Flight III Burke near you is a Digital Array Radar with all the bells and whistles of a radar of that kind. A promo video from Lockheed Martin:

In light of the above quote, I think it is understandable why the new X-band radar for the Flight III is still under development.

The abstract of that article reads:

Digital beamforming phased arrays are becoming increasingly common, with rapid development expected to cover a wide range of applications and frequencies from L- through W-Band. The objective of a digital beamforming phased array is the simultaneous generation of many antenna patterns for a single set of receiver data. Digital beamforming relies on the coherent addition of the distributed waveform generator and receiver channels, placing additional challenges on the synchronization of the many channels and system allocations of noise contributions. At high frequencies or for low power systems, every-element digital beamforming is challenged by size and power requirements. The use of analog beamforming reduces the number of waveform generator and receiver channels required to be digitized. Analog beamforming is accomplished by adjusting the phase and amplitude of the signal at the individual antenna element to steer the direction of the radiation pattern. The semiconductor industry is enabling new system developments with high speed converters, SiGe beamformers, microwave frequency conversion and front-end modules.

Bold face is mine.

Since you omitted the important part which is about Size. High frequency antenna on a phase array means the distance between the elements are much shorter to around 1/2 of the wavelength. Figure out how tiny is the spacing between elements of an mmWave array.

mmWave however has zilch to do with current naval and military radar systems, which are mostly on the S-band to the X-band, with long range surveillance on the L-band, OTH scan on the metric, and CIWS gun fire control ranging from the X-band to the Ku-band. All of them considerably much longer than mmWave, and should not be a problem with current IC manufacturing technologies.

USA already has a naval X-band AESA radar and that is the SPY-3 on the Zumwalt and the Ford class. The designation SPY-5 is reserved for a Raytheon X-band naval radar.

Delay in SPY-5 maybe more political and budget concerned rather than technical. Do you have to insist on doing digital beamforming per element and not on a subarray level?

How many other countries already have naval X-band AESA radar?

Thales Nederland --- APAR : Germany, Netherlands, Denmark. Thales is now offering GaN based Block II APAR for customers.
Russia --- Poliment for Admiral Gorshkov; Zaslon M for Gremyasaschy class corvettes.
China --- Type 055; also on new radar for Type 075
Japan --- Akizuki and Asahi class destroyers. In addition they also have C-band naval AESA.

As in the case of Thales, Russia and Japan, they already have gone to the second generation, with Block II APAR for Thales, Zaslon M for Russia and Japan with the Asahi class.

 

[Anlsvrthng]

The F-35 to my knowledge is the only fighter platform with true digital beamforming capability - at sub array level. Such capability is provided by FGPAs and not GPUs. It is rumored that the F-35 uses six of it.

That doesn't make sense, are you aware ?
Beamforming happens at the element level, with per element phase shifter.

So there is no "sub array digital beamforming".

And, again, how can I synchronise on 446MHz my two radios , to emit 2db amplified beamformed signal ?

 

[Anlsvrthng]

F-22's AESA radar started development in the 1990s. By today's standards in AESA advancement, its already an antique.

Even those brick like AESA arrangements I have been showing you about is already getting old.

This is how the future looks like. Note the FPGA digital beamformers all arranged at the sides of the PCB that contains all the elements.

That is analogue beamformer.
There are the 4 bit analogue phase shifter lines to each element, if you check the tracing .

The four line leading to each element doing it.
And by your definition this is a PESA, not an AESA, because the amplification happens prior of the phase shifter.

The phase shifters controlled digitally, like done on the the majority of the AESA and PESA radars.

Digital beamforing means there is no phase shifter, only per element Tr/Rx modules, with a shared reference clock .
It is NOT that.

Again, there is no 200 GHz CPU/GPU/DSP/FPGA to do digital beamforming in the 10 GHz domain.

 

[nlalyst]

F-22's AESA radar started development in the 1990s. By today's standards in AESA advancement, its already an antique.

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 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.

You honestly think that modern Telecom still uses any analog?

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.

USA already has a naval X-band AESA radar and that is the SPY-3 on the Zumwalt and the Ford class.

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.

 

[Tam]

That is analogue beamformer.
There are the 4 bit analogue phase shifter lines to each element, if you check the tracing .

The four line leading to each element doing it.
And by your definition this is a PESA, not an AESA, because the amplification happens prior of the phase shifter.

PESA is not defined by amplification happening prior to the phase shifter. That is utter invention that no one agrees with.

Amplification happens under each element, regardless of the phase shifter is before the amplifer, or after the amplifier. Definition of AESA is that the amplification takes place, in distributed form, with each element on the array itself, and not on a centralized amplifier well back in the array.

The phase shifters controlled digitally, like done on the the majority of the AESA and PESA radars.

Digital beamforing means there is no phase shifter, only per element Tr/Rx modules, with a shared reference clock .
It is NOT that.

AESAs also adopt hybrid Digital and Analog beamforming.

This particular example is for mmwave MIMO for 5G.

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Again, there is no 200 GHz CPU/GPU/DSP/FPGA to do digital beamforming in the 10 GHz domain.

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.

 

[Brumby]

That doesn't make sense, are you aware ?
Beamforming happens at the element level, with per element phase shifter.

So there is no "sub array digital beamforming".

And, again, how can I synchronise on 446MHz my two radios , to emit 2db amplified beamformed signal ?

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 .

“Moving to digital arrays gives us the ability to have a software-defined RF [radio-frequency] sensor where we can digitally control every radiating element,” says Bill Phillips, director of advanced technology at

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Electronic Systems. “For many years, the vision of elemental digital arrays was unachievable; the device technology was not ready. Commercial investment in system-on-chip technology has made wide-band digital elemental AESAs feasible.”

AESAs form and steer beams electronically by shifting the phase at each radiating element in the array. Conventional phased arrays can form and steer only one beam at a time, but can switch between beams so quickly, it seems almost instantaneous. This allows multiple modes to be time-interleaved. With ACT, an AESA could digitally generate multiple simultaneous beams for different purposes, from different parts of the array.

“Arrays will be capable of more things because of digital beam-forming,” says Olsson. “A digital array can form as many beams as the digital signal processing allows. It can simultaneously point many beams in multiple directions, and also point holes in certain directions. That is not our reason for pursuing ACT, but it is a benefit of the architecture.”

While most operational AESAs have analog beam-forming, there is a trend to move digital processing closer to the face of the array to reduce cost and increase flexibility. 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.

Source : Darpa’s ACT Program Digitizes Active Arrays. Mar 12, 2015

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