Almaz S-300: China's "Offensive" Air Defense

crobato

Colonel
VIP Professional
All radars have the same practical purpose, but just because they do doesn't make them intechangeable. It's surprising that you'd still try to spin your way out of this one, but I guess as a mod you are free to do as you wish. Feel free to everlook the differences which make them 2 similar but distinct waveforms.

Those distinctions don't make one "lower power" than the other. In fact, those distinctions don't lower the peak power for either. There might even be a better case for Interrupted CW because the interruptions are blanks that don't have waves at all, while FMCW puts higher frequencies in segments which raises the energy for such. And by the way, even under the FMCW classification, there are different wave forms, e.g. triangular, sawtooth, etc,.

I'm disappointed in you. If you are unable to interpret clearly what I say because you are not well versed enough, that is not my fault. Please don't accuse me of saying things I didn't, and ridiculing me based on that. It's offensive.

You don't have the right, or position, or stature to claim you are "disappointed" with me.

It's quite hard to fathom that you'd actually acknowlege FMCW decreases peak power but deny that it's a LPI technique, despite many texts on LPI radars listing it as one. Perhaps what's stopping you from admiting it is because you have claimed outright earlier that FMCW is not a LPI technique?

Did I ever acknowledge that FMCW decreases peak power? I don't see it in the text and in the form.

What I see in most texts is that they list FMCW not as an LPI, but as way of getting range with CWI.

It only means that FMCW cannot generate the same kind of peak power as pulsed systems do, which means it won't be able to emit in range or the power to detect smaller objects. To put it simply, that's the general disadvantage of CW radars, and this lack of power is what caused pulsed radars to replace them in the first place.

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"FMCW systems are often used for radar altimeters, or in radar proximity fuzes for warheads. These systems do not have a minimum range like a pulsed system. However, they are not suitable for long range detection, because the continuous power level they transmit at must be considerably lower than the peak power of a pulsed system. You may recall that the peak and average power in a pulse system were related by the duty cycle,"

Spin it whatever you want. Your interpretation is faulty. For a radar to do its job, it requires it needs to reflect the target with some power.
 

crobato

Colonel
VIP Professional
Again, goes to show how much you do not know. Try picking up Jane's Radar and electronic systems or some other radar textbooks. Most search radars are pulse doppler radars. Those radars which use uninterrupted continuous waves are comparatively fewer, and FMCW is only common among those which have ranging as a function. Which in the end means that FMCW radars are very few, limited to Scout, Pilot, Page and a few others.

Really, want to read some text books?

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"CW radars have the disadvantage that they cannot measure distance, because there are no pulses to time. In order to correct for this problem, frequency shifting methods can be used. In the frequency shifting method, a signal that constantly changes in frequency around a fixed reference is used to detect stationary objects. When a reflection is received the frequencies can be examined, and by knowing when in the past that particular frequency was sent out, you can do a range calculation similar to using a pulse. It is generally not easy to make a broadcaster that can send out random frequencies cleanly, so instead these Frequency-Modulated Continuous Wave radars (FMCW), use a smoothly varying „ramp” of frequencies up and down."

This site has a lot of military radars and goes about explaining them, but I don't see here any explanation how FMCW lowers the average power over CW or how it is for LPI applications.

Rather its very different.

Unique?

"This kind of radar is used as „radar altimeter” often. The radar altimeter is used to measure the exact height during the landing procedure of aircraft. Radar altimeters are also a component of terrain avoidance warning systems, telling the pilot that the aircraft is flying too low or that terrain is rising to meet the aircraft."

Oh I see that's unique eh?
 

crobato

Colonel
VIP Professional
Detection range increases exponentially with increases in power transmitted. Because the FMCW radar's sidelobes are so low, this is at the very low end of the curve, hence the increase in ESM sensitivity isn't enough to compensate. In pulse doppler radars which form the majority of military radars however, to achieve the same range would require a much higher peak power output and a correspondingly higher sidelobe power output.

Oh please. You are so wrong here.

You really need to study the basics of pulse radar, why in the first place, they are superior over longer ranges than CW radar.

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Short range target Detection= "Better for longer ranges"

Target range Discrimination = Superior due to narrow pulse width and other techniques

Sure, emit nothing and you will be undetectable by any intercept receiver. Any fool knows that. What FMCW offers is much lower average power required than pulse doppler radars to achieve the ranges against a target (assuming all other factors remain equal) it can. That, you don't know.

Against the same longer ranges, you are wrong.

And if its really low power for long ranges you want, you're barking up the wrong tree. The right tree is pulse compression.
 

Kongo

Junior Member
Those distinctions don't make one "lower power" than the other. In fact, those distinctions don't lower the peak power for either. There might even be a better case for Interrupted CW because the interruptions are blanks that don't have waves at all, while FMCW puts higher frequencies in segments which raises the energy for such. And by the way, even under the FMCW classification, there are different wave forms, e.g. triangular, sawtooth, etc

Why are you shifting the goalposts now? I have been comparing the FMCW to normal pulse doppler, or if you prefer, pulse compression radars all along. Perhaps you finally saw that your position was untenable?

You don't have the right, or position, or stature to claim you are "disappointed" with me.

Well, as a mod I thought you would have the honesty to admit when you made a false accusation. Seems like I'm wrong.

Did I ever acknowledge that FMCW decreases peak power? I don't see it in the text and in the form.

CW decreases peak power because it spreads out the energy over time. FM is there to provide the ranging component. After all this time, you still couldn't get the basics. What's the point of spilling out links to textbooks if you don't understand them?

What I see in most texts is that they list FMCW not as an LPI, but as way of getting range with CWI.

FMCW is indeed a method to get range out of a CW waveform, however it is also an inherently LPI waveform, hence it's a LPI technique.

This site has a lot of military radars and goes about explaining them, but I don't see here any explanation how FMCW lowers the average power over CW or how it is for LPI applications

Again you display your ignorance, or is it your inability to read? FMCW, or any other waveform with a 100% duty cycle allows for the peak power to equal average power. That is how peak power is reduced. If you truly understood that, you won't need any textbook to state it explicitly. That you require me to explicitly show you such a statement shows clearly you don't understand what you are posting. Again, peak power is what ESM looks out for, average power is what radars use to detect targets.

It only means that FMCW cannot generate the same kind of peak power as pulsed systems do, which means it won't be able to emit in range or the power to detect smaller objects. To put it simply, that's the general disadvantage of CW radars, and this lack of power is what caused pulsed radars to replace them in the first place.

Exactly. So why are you using a FMCW radar to back yourself up when the majority of search radars, which is what ESM aircraft like Rivet Joint go about searching for, use pulse doppler radars!?

Rather its very different.

Unique?

As I have repeatedly said, unique in comparison to other search radars. Why are you bringing in altimeters and fuses when iwe are obviously talking about bigger radars which is what Rivet Joint etc are there for? As I've said earlier, "Most search radars are pulse doppler radars."

Against the same longer ranges, you are wrong.

And if its really low power for long ranges you want, you're barking up the wrong tree. The right tree is pulse compression.

:rofl: This is totally ironical. That's the basis of what I've been trying to tell you all this while. Since search radars are what the Rivet Joint is looking for, then FMCW radars cannot be used to back yourself up, since FMCW only form a small number of search radars. It simply is the wrong example.
 

crobato

Colonel
VIP Professional
Eh? What untenable? The only one that has been switching goal posts is you.

The reason why FMCW doesn't work well at range is that its lousy at it. You do need peak power and you do need pulse width to get the range and discrimination.

CW decreases peak power because it spreads out the energy over time. FM is there to provide the ranging component. After all this time, you still couldn't get the basics. What's the point of spilling out links to textbooks if you don't understand them?

Go learn some radar basics. You spread out energy over time, you lose range due ot energy attrition via attenuation. Hence why most long range radars are Pulse Doppler. For a given the farther it goes, you're going to need higher energy for CW than you do with a pulse. You want to package the energy into a pulse because for the same amount of energy, it can travel much farther.

Again you display your ignorance, or is it your inability to read? FMCW, or any other waveform with a 100% duty cycle allows for the peak power to equal average power. That is how peak power is reduced. If you truly understood that, you won't need any textbook to state it explicitly. That you require me to explicitly show you such a statement shows clearly you don't understand what you are posting. Again, peak power is what ESM looks out for, average power is what radars use to detect targets.

Read it if you please.

"For a continuous wave system, the duty cycle is one, or alternatively, the peak power is the same as the average power. In pulsed systems the peak power is many times greater than the average."

Who is the fool here? What it means is that the peak power cannot be greater than the average power.

Its not "FMCW, or any other waveform with a 100% duty cycle allows for the peak power to equal average power. " It just means your peak power cannot be greater than the average power, while pulsed systems can generate peak power many times in excess of their average power. Its a limitation not an advantage.

Exactly. So why are you using a FMCW radar to back yourself up when the majority of search radars, which is what ESM aircraft like Rivet Joint go about searching for, use pulse doppler radars!?

LOL. They are also looking for fire control radars which will use CWI.

Again, peak power is what ESM looks out for, average power is what radars use to detect targets.

Late eighties ESM you mean. I don't see why its only peak power from here on. You need to look for the total amount of energy. You are already contradicting yourself---

"AL Hume and CJ Baker co-authored titled "Low probability of intercept radar strategies", it was clearly stated that "any free-space detection range is possible, given a sufficiently sensitive receiver."

FMCW is indeed a method to get range out of a CW waveform, however it is also an inherently LPI waveform, hence it's a LPI technique.

No. CW is the inherently LPI waveform, only when its low power. FMCW is just one of the many modulation techniques for CW.

This is totally ironical. That's the basis of what I've been trying to tell you all this while. Since search radars are what the Rivet Joint is looking for, then FMCW radars cannot be used to back yourself up, since FMCW only form a small number of search radars. It simply is the wrong example.

And suddenly its just search radars eh? What about fire control radars that use CW?
 

crobato

Colonel
VIP Professional
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# LEMZ 76N6 Clam Shell FMCW acquisition radar

Low flying aircraft equipped with many models of older and established radar warning receivers and trackbreaking deception jammers may be vulnerable to attack by the S-300PMU/PMU-1 (SA-10c & -10d "Grumble") SAM system. Such equipment may not be able to detect and jam the 76N6 "Clam Shell" low-altitude search and acquisition radar used by the S-300PMU & PMU-1 series. Currently being marketed ... [+]

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"The Clam Shell is a low altitude FMCW (frequency modulated continuous wave) search and acquisition radar designed to detect and track approaching and receding low radar cross section (RCS) targets, particularly cruise missiles. The system will detect targets at extremely low altitudes in ground clutter under intense ECM conditions. This system is described as fully automatic and provides target track information for the fire control system of the static SA-10A or mobile SA-10B Grumble area defence SAM. Approaching and receding target velocity, range and bearing are provided, with selectable 1 or 6 degree vertical beamwidths, and selectable beam polarisation."

Something that has to be read in particular.

" The Clam Shell transmitter, embedded in the FA52MU Receiver/Transmitter Module, produces a high purity CW signal for search mode operation, with imposed low frequency FM modulation for ranging to targets. "


Something more about the Scout from Janes. Looks like it has a pulse option.

"SCOUT Mk 2 is an LPI surveillance/navigation radar that makes use of the Frequency Modulated Continuous Wave (FMCW) technique to 'see without being seen'. As such, the radar is claimed to be 'virtually impossible' to intercept by means of electronic support systems and/or anti-radiation missile seekers. Physically, SCOUT Mk 2 is a solid-state equipment that incorporates an antenna/FMCW transceiver assembly and a processor unit. Of these, the antenna used is a dual array that features 'optimal' isolation between its transmit and receive elements in order to maximise range performance. The system's above- and below-decks elements are connected via a single 'thin' cable and the radar can be operated as a stand-alone entity or as part of a fully integrated navigation and LPI radar architecture. Here, SCOUT Mk 2 can be integrated with a pulsed I-band navigation radar (with the SCOUT Mk 2 antenna being used (with the addition of a waveguide) for both pulse and FMCW functionality) and its video data with a command and control system. Other system features include: 'extremely high' range resolutionan optional pulse transceiver (for facilitate pulse/FMCW radar functionality)use of a display processor/automatic radar plotting aid display combination when employed in a combined pulse/FMCW radar application."
 

Kongo

Junior Member
The reason why FMCW doesn't work well at range is that its lousy at it.

You know, posting what i said earlier doesn't really gain you points at all. :rofl: Let's go to the very first post I made on this subject. "But if FMCW was so good, why isn't every radar utilising it? The flipside is that FMCW severely restricts range. "

Read it if you please.

"For a continuous wave system, the duty cycle is one, or alternatively, the peak power is the same as the average power. In pulsed systems the peak power is many times greater than the average."

Who is the fool here? What it means is that the peak power cannot be greater than the average power.

Its not "FMCW, or any other waveform with a 100% duty cycle allows for the peak power to equal average power. " It just means your peak power cannot be greater than the average power, while pulsed systems can generate peak power many times in excess of their average power. Its a limitation not an advantage.

In a pulsed doppler radar which has a duty cycle is less than one, peak power will be more than average average power, but peak power will decrease towards average power the higher the duty cycle. Since reducing peak power is a LPI measure, FMCW is a LPI measure. Depending on the characteristic you are looking for, it may be either a limitation or advantage. I have clearly stated this in my very first post. Why are you repeating it back to me now? Are you so happy over your new found knowledge that you have to share it with us even though it is just a repeat of what i've said in the beginning?

LOL. They are also looking for fire control radars which will use CWI.

Yes, an careless omission on my part there. But surely you are not trying to use the "ICW, CW and FMCW all interchangeably usable" spin which has been fully debunked again?

Late eighties ESM you mean. I don't see why its only peak power from here on. You need to look for the total amount of energy. You are already contradicting yourself---

"AL Hume and CJ Baker co-authored titled "Low probability of intercept radar strategies", it was clearly stated that "any free-space detection range is possible, given a sufficiently sensitive receiver."

Nothing contradictory there, if you understand what it means. Clearly you don't.

No. CW is the inherently LPI waveform, only when its low power. FMCW is just one of the many modulation techniques for CW.

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"Frequency-modulated CW, or FMCW, is the oldest LPI approach" Well, at least now you do know much more than you did 2 days ago. Let's have a blooper review. Crobato - "FMCW does not improve low probability of interception..."

And suddenly its just search radars eh? What about fire control radars that use CW?

Again, displaying more of what you don't know than what you do. Illuminators use pure CW. These cannot get range and thus don't qualify as radars. I hope you know what the acronym RADAR stands for.

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# LEMZ 76N6 Clam Shell FMCW acquisition radar

Low flying aircraft equipped with many models of older and established radar warning receivers and trackbreaking deception jammers may be vulnerable to attack by the S-300PMU/PMU-1 (SA-10c & -10d "Grumble") SAM system. Such equipment may not be able to detect and jam the 76N6 "Clam Shell" low-altitude search and acquisition radar used by the S-300PMU & PMU-1 series. Currently being marketed ... [+]

Really, I hope that by posting one more example of a FMCW radar you don't mean I should give a list of all the radars that use pulse dopplers here? That'll really flood the place long after you finish with FMCW radars used for search. I said Scout is fairly unique because it uses FMCW. I didn't say it is unique and one and only. I've got to make this clear because I see that you have a tendency to put words in my mouth when you are getting... shall we say.. cornered?
 

crobato

Colonel
VIP Professional
Cornered, don't make me laugh. You just got the internet equivalent of a knocked down.

Let us review what you said.

"Since search radars are what the Rivet Joint is looking for, then FMCW radars cannot be used to back yourself up, since FMCW only form a small number of search radars. It simply is the wrong example."

LOL.

And so this is not important?


# LEMZ 76N6 Clam Shell FMCW acquisition radar

Low flying aircraft equipped with many models of older and established radar warning receivers and trackbreaking deception jammers may be vulnerable to attack by the S-300PMU/PMU-1 (SA-10c & -10d "Grumble") SAM system. Such equipment may not be able to detect and jam the 76N6 "Clam Shell" low-altitude search and acquisition radar used by the S-300PMU & PMU-1 series. Currently being marketed ... [+]


This is not relevant?

Yes, an careless omission on my part there. But surely you are not trying to use the "ICW, CW and FMCW all interchangeably usable" spin which has been fully debunked again?

And how did you debunk that? By stating dogmatically---without proper explanation---that FMCW is LPI?

Since reducing peak power is a LPI measure,

LOL so is every modulation form of CW, ICW, FM-ICW, and what about the different forms of FMCW, e.g. linear, non linear, triangular, etc,.

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"Frequency-modulated CW, or FMCW, is the oldest LPI approach" Well, at least now you do know much more than you did 2 days ago. Let's have a blooper review. Crobato - "FMCW does not improve low probability of interception..."

You got a problem with language. CW is the LPI approach. FM is just modulation.

And nice showing the link because

"Although simple to implement, FMCW creates high side lobe peaks, which creates many problems, and led to its replacement by phase shift keying (PSK), frequency shift keying (FSK), and frequency hopping. "

LOL.

Let's put it in bold what you said.

Because the FMCW radar's sidelobes are so low, this is at the very low end of the curve, hence the increase in ESM sensitivity isn't enough to compensate.

I didn't say it is unique and one and only.

Wow what a spin. the whole point of you saying its unique or few is to make it look its irrelevant.

Does the S-300's Clamshell irrelevant then?

The number of FMCW search radars known is only in proportion to those who are willing to admit it. That's also good reason to be relevant. And don't forget the fire control radars too? Suddenly its not Rivet Joint's job to look for them too?
 

crobato

Colonel
VIP Professional
Again, displaying more of what you don't know than what you do. Illuminators use pure CW. These cannot get range and thus don't qualify as radars. I hope you know what the acronym RADAR stands for.

Yeah, and I showed you examples of Standards and ESSM using ICWI.

And because they're not radar, RWRs are not supposed to pick them their illumination signals right?

Your link.

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Page 1057, last sentence.

"All these modulated CW radars are able to measure range."
 

Kongo

Junior Member
Cornered, don't make me laugh. You just got the internet equivalent of a knocked down.

Let us review what you said.

"Since search radars are what the Rivet Joint is looking for, then FMCW radars cannot be used to back yourself up, since FMCW only form a small number of search radars. It simply is the wrong example."

LOL.

And so this is not important?


# LEMZ 76N6 Clam Shell FMCW acquisition radar

Low flying aircraft equipped with many models of older and established radar warning receivers and trackbreaking deception jammers may be vulnerable to attack by the S-300PMU/PMU-1 (SA-10c & -10d "Grumble") SAM system. Such equipment may not be able to detect and jam the 76N6 "Clam Shell" low-altitude search and acquisition radar used by the S-300PMU & PMU-1 series. Currently being marketed ... [+]


This is not relevant?

Does the S-300's Clamshell irrelevant then?

The number of FMCW search radars known is only in proportion to those who are willing to admit it. That's also good reason to be relevant.

Again, twisting my words to cover your deficiencies? I never thought that as behavior as fitting for a mod. Where did I say 'not relevant'? By 'wrong example' I meant that you were using a radar which was in the minority as an example to back yourself up. Certainly it is hoped that the Rivet Joint would be effective against all, but life is never perfect. So long as most of the systems can be intercpeted that would still be very good, with the signals from the ones not being able to be intercepted by the Rivet Joint solved through other means. Since you finally agree that most of the search radars use pulse doppler since FMCW is range limited, then you using a FMCW radar as an example to back yourself up is inherently wrong.

And don't forget the fire control radars too? Suddenly its not Rivet Joint's job to look for them too?

Fire control illuminators, you mean? Yes, these would pose some constraints in terms of detection, but as I recall you and manoverbored were talking about search radars, so why play shift the goalposts again?

And how did you debunk that?

By showing with clear illustration that FMCW was distinct from ICW. Similar but distinct, and only those who didn't know the difference would call the terms as interchangeable in usage.

LOL so is every modulation form of CW, ICW, FM-ICW, and what about the different forms of FMCW, e.g. linear, non linear, triangular, etc,.

Yes, quite right. Increasing the duty cycle to 100% thus making a waveform continuous is a LPI measure. This is what I have been stressing since the first post, and I never claimed that other CW types were not LPI in nature. I don't get why you are so concerned with other CW waveforms? Is it a way to redeem yourself or something?

You got a problem with language. CW is the LPI approach. FM is just modulation.

Repeating to people what people told you won't make you look better. :roll:

And nice showing the link because

"Although simple to implement, FMCW creates high side lobe peaks, which creates many problems, and led to its replacement by phase shift keying (PSK), frequency shift keying (FSK), and frequency hopping. "

LOL.

Let's put it in bold what you said.


Quote:
Because the FMCW radar's sidelobes are so low, this is at the very low end of the curve, hence the increase in ESM sensitivity isn't enough to compensate.

Sad that you are unable to understand things in context. That's the problem with you and the result is you relying on wrong info ass proof. When I say "FMCW radar sidelobes are so low", I meant it in absolute terms, whereas the quote above is relative to other radars. Please try to understand in proper context what you are posting.
 
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