F-22 Raptor pilots practice simulated combat against Pakistan, UK & France Pilots

[gambit]

++
http://www.defence.pk/forums/1131582-post139.html

Here you go...

What all that stuff you posted basically boils down to is the assumption that the F-22s radar return on high frequency X band radar, which is the radar frequency traditionally used for detection, tracking and terminal homing (because of its precision) that to track an F-22 requires the radar to track everything insect size and larger, which is too much. To categorise the insects and other things floating around like Clouds as noise is to also categorise the F-22 as noise so it becomes invisible.

Effectively...Yes...But clarifications to follow...

There was a similar problem a few decades ago with the An-2 biplane that the Soviets used as a light transport and also for dropping small teams of paratroopers.

When flying low and slow a modern radar looking down would detect the plane but the plane would be hidden in the enormous radar reflection of the ground. To remove the ground as a reflector they simply used the doppler effect so anything that was not moving at 120km/h was removed from the radar display so that cars did not appear as targets. This meant that the An-2 flying at 90km/h also disappeared and so it was the first stealth aircraft!

Sure...If the goal is to credit who has the first 'stealth' aircraft, then you can speciously claim said credit. But no one is going to take said claim seriously.

The difference in this case is that instead of looking down into a huge reflection of the ground looking for an insect sized target you are looking up and let me tell you there are no insects above 10,000m let alone the 20,000m operating ceiling of the F-22. Another thing is that few insects fly at anywhere near the speed of the F-22 so actual insects and clouds and other things that might be mistaken for F-22s can be removed as noise if they are moving at less than 50km/h which should remove everything except for those super cruising F-22s.

There is a grossly flawed understanding of 'clutter' in general. To start...No one knows what the Earth itself look like from a radar perspective because the Earth is covered with 'stuff', from flora to fauna and everything in between. A bird may have the same reflectivity as a rock that is smaller than itself. A shrub may have the same radar reflectivity even though its volume is ten times larger than both bird and rock. Cumulatively, we have 'ground clutter'. To filter out 'ground clutter' is to filter out anything that falls within a certain reflectivity range that made up 'ground clutter', including the Doppler components of any object within that range. It is not difficult to understand the argument that: No movement, no Doppler component, and in order to exploit the Doppler component of a moving object, you must be focused on that object in the first place, and in order to focus on one or more objects you must be able to distinguish them based upon some criteria.

Moving on...A 'decibel' is a base 10 difference between two power levels.

HowStuffWorks "What is a decibel and how is it measured?"

On the decibel scale, the smallest audible sound (near total silence) is 0 dB. A sound 10 times more powerful is 10 dB. A sound 100 times more powerful than near total silence is 20 dB. A sound 1,000 times more powerful than near total silence is 30 dB.

So we should see this scaling:

http://upload.wikimedia.org/wikipedia/en/a/a0/X_and_log_x.svg

If the bird has a .05db difference over the rock and this difference falls within the rejection threshold because the radar equipment is not capable of separating out objects with this difference level, then it does not matter if the bird is flying, hence having a Doppler component, and the rock is on the ground, hence having no Doppler component, because both will be classified as 'clutter' and rejected. If the radar equipment is capable of separating out objects down to .0000000000005db difference, which would make it a really outstanding piece, then we can have different levels of rejection thresholds. We can filter out individual leaves, one leaf that is swaying in the wind and one that is still. We can see bird's Doppler component when it is moving on the ground next to the rock and certainly when it is in flight.

Often, when biologists 'sees' insects on their radar scopes, they do not see distinct units but rather the swarm itself, be it locust or the annual Monarch butterfly migration. This is only a reinforcement of basic radar reflective behavior. The radar signal, as a conical beam that expands with distance, reflect off individual insect (or bird) and this reflection in turn reflect off another insect (or bird) in the mass and so on. The effect is also called 'reverberation'. The result is that for insect swarms or flocks of birds, radar detection is usually volumetric, meaning the detection is based upon the cumulative effect from all the reflections inside the insect swarm or the flock of birds. Same idea for a tree. The radar signal will have multiple reflections off the individual leaves and the result is an electronic 'tree'. If a single insect drop out of the swarm, a single bird drop out of the flock, or a single leaf fall off the tree, each will NOT be seen by the radar. This type of clutter is called 'volume clutter': insect swarms, flocks of birds, flora, or various meteorological phenomenon such as rain/snow fall.

General Dynamics F-111 Aardvark / EF-111 Raven

The F-111's automatic terrain-following radar system flies the craft at a constant altitude following the Earth's contours. It allows the aircraft to fly in valleys and over mountains, day or night, regardless of weather conditions. Should any of the system's circuits fail, the aircraft automatically initiates a climb.

There were many F-111 sorties that came back with green evidences on an aircraft's underside. What happened was that even though the hill itself is full of trees and they contributed to a volumetric RCS that follows the hill's contour, one tree stands alone, or it was tall enough to stand out from the rest, so it was not detected and the aircraft clipped it as it flew over the hill top. This was rare but not unknown in the F-111 community. When such 'accidents' did occurred, it was always at very low altitudes and under TF 'Hard' setting.

A volumetric RCS can have two Doppler components: from itself as a moving volume, and from the individual units. But if any unit is detached from the volume, its Doppler component will be lost to the seeking radar unless the radar is capable of distinguishing this unit in the first place.

Centimetric freqs can distinguish individual insects, even within a swarm, BUT only at a few hundred meters.

THE FEASIBILITY OF USING VERTICAL-LOOKING RADAR TO MONITOR THE MIGRATION OF BROWN PLANTHOPPER AND OTHER INSECT PESTS OF RICE IN CHINA - Riley - 2008 - Insect Science - Wiley Online Library

The recent development of automatically operating, inexpensive vertical-looking radar (VLR) for entomological purposes has made it practical to carry out routine, automated monitoring of insect aerial migration throughout the year. In this paper we investigate whether such radars might have a role in monitoring and forecasting schemes designed to improve the management of the Brown Planthopper (BPH), Nilaparvata lugens, and of associated rice pest species in China. A survey of the literature revealed that these insects typically migrate at altitudes between 300 to 2 000 m above ground level, but calculations based on BPH radar scattering cross-sections indicated that the maximum altitude at which they individually produce signals analysable by current VLRs is only ˜ 240 m. We also show that coverage over most of the flight altitudes of BPH could be achieved by building a VLR using a wavelength of 8.8 mm instead of the 3.2 cm of existing VLR, but that such a radar would be expensive to build and to operate. We suggest that a more practical solution would be to use a 3.2 cm VLR as a monitor of the aerial movement of the larger species, from which the migration of rice pests in general might be inferred.

Translation: We can use cm and mm wavelengths to detect individual insects but only out (or up) to 240 meters. For the Brown Planthopper (BPH), each bugger weighs about 1-2mg and 2-3mm in body length. Using wavelength 3.2cm of the standard X band radar...

Radar - Wikipedia, the free encyclopedia

X 8–12 GHz 2.5–3.75 cm Missile guidance, marine radar, weather, medium-resolution mapping and ground surveillance; in the USA the narrow range 10.525 GHz ±25 MHz is used for airport radar; short range tracking. Named X band because the frequency was a secret during WW2

...We have an estimated RCS of 2x10-4 cm/squared at 200-300 meters distance PER BUG. Beyond this distance and the radar will have to rely upon the volumetric density of a BPH swarm to know if there are any BPH aflight. Millimetric freqs are better but this wavelength matches the diameter of individual rain drops. The result is that a mm wavelength signal will be intercepted by rain drops or anything similar before the signal can pick up any bug. This is why the mm wavelengths are usually confined to laboratory and/or highly specialized detection schemes outside of military applications.

The X band is centimetric but it does not matter the radar perspective, up or down looking, the distance involve between radar and aircraft renders the F-22 extremely difficult to create any statistical analysis by the seeking radar. As if looking up is not bad enough, there is the proverbial 'double whammy' if the radar is in a 'look down' perspective in that: Not only must the radar deal with a volumetric density that could be dismissed by itself but also that this volume's RCS is part of the 'ground clutter' rejection threshold.

Clutter is from radar echoes. Noise is NOT clutter, is independent of clutter, can exist without clutter, is hardware related, and is usually affected by time and temperature. Clutter + Noise = Interference. The F-22's RCS signal level is well within the clutter rejection threshold OR internally generated noise. So even if there are no flock of birds or swarms of insects around, odds are excellent that a radar system's own noise already blanket the F-22. The argument that the F-22's Doppler component will give it away despite its 'insect' or 'bird' level RCS came from a flawed understanding of radar detection, clutter types, and noise.

Still think you can detect the F-22?

Another issue is of course that the shape of an aircraft only matters to radar that can actually detect shape like X band radar. L and N band radar resonates of the aircraft as a single pulse and detection range is not effected by shaping at all so a wing mounted L band radar that can detect an Su-27 at 400km can detect a T-50 or an F-22 at 400km too.

No radar signals detect any 'shape'. The entire paragraph is absolutely nonsensical.

That is why they haven't wasted billions making the T-50 super stealthy... there will be no point in 20 years.

They did not waste any billions because they did not know how to build a 'stealthy' one.

Regarding the shooting down of the F-117 lets put it in perspective.

Yes...We should.

It was NATO vs Serbia. NATO that looks on paper to be the most powerful military force the world has ever seen vs Serbia.

Does not matter if it was NATO. An irrelevant argument.

The F-117 was claimed to be completely invisible, undetectable.

No one claimed so.

It was going to go into the Soviet Union in the 1980s completely undetected but an enormous range of radars large and small and evade S-300 and S-300V SAM sites and Mig-31 interceptors and Su-27 fighters (note both with IRST sensors) and drop laser guided bombs on very high priority targets and then fly home in safety despite thousands of enemy fighters patrolling the skies etc etc etc.

If the shoot down was luck then why didn't the Iraqis get some too?

Because the Iraqi air defense was not so fortunate? Fortune and probability are not the same thing.

If you can base an air defence around luck why waste money on guided SAMs when unguided Grad rockets are much cheaper... just fit them with airpresure fuses so they explode at certain heights and fire barrages everytime you hear an aircraft engine?

Who said anything about using fortune as a basis for defense? Again...Fortune and probability are not the same thing. This argument is based upon a flawed understanding of fortune versus probability.

Try this.
Get a digital camera and go out into the middle of nowhere that is under the flight path of an airport but far enough away from any airport so that all the aircraft are at 10,000m or so (ie 30,000ft would be a normal operating height for an airliner) so you can't hear its engines.
Close your eyes and get your map out and look up the flight schedule and work out, based on airspeed and time when the next aircraft flys over.
Using that fly over time you can take 30 shots of the sky but only planes caught in the dead centre of the picture count.
You have to take the photos with your eyes closed and you are not allowed to look for aircraft before or even after you take the photos.
Now do it again... at night.
Luck my a$$.
They wouldn't have been able to mass large numbers of SAMs to fire at the F-117 simply because a large group of SAMs would be detected and destroyed.

Nonsense. Currently, once a SAM is in flight, all an aircraft can do is evade, not try to shoot the missile. Perhaps what you mean is that the launchers would be destroyed? This argument ignored history, particularly the North Vietnamese air defense networks.

They probably only had one or maybe two launchers so that means about 6 shots maximum at the target... and if you can't see the target your chances of hitting it with even 6 shots is so close to zero it is not worth the effort.

By this logic, all soldiers should be superb marksmen, one-shot-one-kill. After all, if a soldier need to shoot off several rounds to increase his odds of hitting his target and with no guarantees to boot, it is not worth the effort of shooting.

The reality is that the F-117 was not invisible,...

The US never claimed it was. This is a weak argument in trying to downplay the its effectiveness.

...what they probably did was illuminate the target with the radar of another battery from behind where the F-117 was coming from and so the radar emissions scattered from the target away from the emitting antenna would be reflected towards other batteries based in other places.

Probably...??? This is called a 'bi-static' radar configuration. Some air defense training call it 'electronic bracketing'. Your usage of the word 'behind' is indicative of a highly speculative argument. In a bi-static configuration, the reflection off a body that is from another transmitter is used by a physically and geographically distinct receiver to determine if the target produced a valid return. There is no 'behind', only approach direction. The catch for an effective bi-static radar attack, or bracketing, is that both stations must be in sync with each other as to when the transmitter will go active, its transmit freq, and the direction of the transmit.

The radar cross section (RCS) valuation of any body is essentially a 'fictitious' argument. This valuation is a 'fiction' in the sense that if no radar then no RCS. If the distance changes, then the RCS value changes. Same for freq employed, or transmit mode, such as pulsed or continuous wave (CW). The bi-static RCS of any object is always greater than its mono-static RCS but this assume that the F-117 was ALREADY under radar capture and its bi-static RCS is being used for greater odds of a successful SAM intercept. This is too much of an assumption that we cannot take it at face value.

This means several things... first it means they knew what the target was going to be... not rocket science... they were there to defend something so they knew what the target of any plane in that area was.

You need to clarify the context of the word 'target' here. From an air defense perspective, the 'target' is an attacking aircraft. From the attacking aircraft's perspective, the 'target' is whatever on the ground that has some value. Lack of proper context rendered this argument worthless.

Second it means they knew the direction it was coming from, which again is a no brainer because I am sure they would have taken steps to determine where NATO deployed its aircraft to and which were where.

After several attacks it would be a 'no brainer'. Nothing spectacular from the Serbian air defense here.

Third it means that there was a spy at the NATO base who watched the F-117s take off to pass that information on to the Serbian air defences... not really a surprise.

This has been established. Still no 'Wow' factor here.

Fourth... and most importantly they would need to aim the guidance beam at the F-117 and keep it on it for the missiles to guide.

Guidance beam? This is still under the assumption that the F-117 was detectable in the first place. Too speculative.

These SA-3s are not vanilla old models they have had upgrades and those upgrades probably included optical backup guidance which was probably used by the first unit to mark the aircraft with a pencil radar beam.

Probably? We need something more concrete. Else the default position is -- no.

I rather doubt luck is why the F-117 was brought down, that would take a lot of organisation and coordination.

The 'luck' here is not about how the Serbian air defense was able to exploit NATO's predictability, although it is commendable that they did. The 'luck' here is that several missiles were launched and one of them successfully damaged the aircraft. The tactic is not new and is called 'spray and pray'.

The reason the Serbs didn't seem to do very well with only two confirmed kills is simply because NATO was so scared it operated above the effective altitude of most Serbian systems. Another factor often ignored in the west is that the west used a lot of unmanned platforms and they lost something like 50 of those during the campaign.

Utter BS. Wild Weasels continued to harass the Serbian air defense at within SAM range. If whatever it was that Zoltan Dani did to make it so effective against the F-117, it should have been a hundred times more effective against these Wild Weasels fighters. The UAV combat loss is nothing more than red herring argument.

If the Serbian Air Defence Force failed because it only brought down 2 manned aircraft then the all powerful NATO force failed because after 74 odd days of total air superiority and air domination it completely failed in its mission to defeat the Serbian armed forces, and the Serbian air defence forces were as dangerous to NATO aircraft on day 74 as they were on day 1.

The air campaign did what it was supposed to do -- control the air space. To defeat the Serbian military it would have required a ground campaign. The dispute is not about whether the Serbian air defense was successful or not. The dispute is about the ridiculous claim that the F-117 was effectively detected, tracked, and targeted.

Sounds like a fail fail fail for NATO to me.

Sounds like a fail fail fail argument for the Serbian air defense to me.

In the end NATO had to resort to lying to Russia to make it think it would have a role in the peacekeeping afterwards to get the Serbs to sign and when the Russians found they had been double crossed they raced forces to Pristina.
The US General in charge reacted by ordering the local British forces to take Pristina, by force if necessary... to which the British General Michael Jackson (no joke... look it up) told him to get stuffed, that he would have to work with the Russians and he wasn't going to start WWIII over this.
Sensible chap IMHO. (The brit, not the yank).

This is a political argument.

 

[amalakas]

Here you go...


Effectively...Yes...But clarifications to follow...


Sure...If the goal is to credit who has the first 'stealth' aircraft, then you can speciously claim said credit. But no one is going to take said claim seriously.


There is a grossly flawed understanding of 'clutter' in general. To start...No one knows what the Earth itself look like from a radar perspective because the Earth is covered with 'stuff', from flora to fauna and everything in between. A bird may have the same reflectivity as a rock that is smaller than itself. A shrub may have the same radar reflectivity even though its volume is ten times larger than both bird and rock. Cumulatively, we have 'ground clutter'. To filter out 'ground clutter' is to filter out anything that falls within a certain reflectivity range that made up 'ground clutter', including the Doppler components of any object within that range. It is not difficult to understand the argument that: No movement, no Doppler component, and in order to exploit the Doppler component of a moving object, you must be focused on that object in the first place, and in order to focus on one or more objects you must be able to distinguish them based upon some criteria.

Moving on...A 'decibel' is a base 10 difference between two power levels.

HowStuffWorks "What is a decibel and how is it measured?"

So we should see this scaling:

http://upload.wikimedia.org/wikipedia/en/a/a0/X_and_log_x.svg

If the bird has a .05db difference over the rock and this difference falls within the rejection threshold because the radar equipment is not capable of separating out objects with this difference level, then it does not matter if the bird is flying, hence having a Doppler component, and the rock is on the ground, hence having no Doppler component, because both will be classified as 'clutter' and rejected. If the radar equipment is capable of separating out objects down to .0000000000005db difference, which would make it a really outstanding piece, then we can have different levels of rejection thresholds. We can filter out individual leaves, one leaf that is swaying in the wind and one that is still. We can see bird's Doppler component when it is moving on the ground next to the rock and certainly when it is in flight.

Often, when biologists 'sees' insects on their radar scopes, they do not see distinct units but rather the swarm itself, be it locust or the annual Monarch butterfly migration. This is only a reinforcement of basic radar reflective behavior. The radar signal, as a conical beam that expands with distance, reflect off individual insect (or bird) and this reflection in turn reflect off another insect (or bird) in the mass and so on. The effect is also called 'reverberation'. The result is that for insect swarms or flocks of birds, radar detection is usually volumetric, meaning the detection is based upon the cumulative effect from all the reflections inside the insect swarm or the flock of birds. Same idea for a tree. The radar signal will have multiple reflections off the individual leaves and the result is an electronic 'tree'. If a single insect drop out of the swarm, a single bird drop out of the flock, or a single leaf fall off the tree, each will NOT be seen by the radar. This type of clutter is called 'volume clutter': insect swarms, flocks of birds, flora, or various meteorological phenomenon such as rain/snow fall.

General Dynamics F-111 Aardvark / EF-111 Raven

There were many F-111 sorties that came back with green evidences on an aircraft's underside. What happened was that even though the hill itself is full of trees and they contributed to a volumetric RCS that follows the hill's contour, one tree stands alone, or it was tall enough to stand out from the rest, so it was not detected and the aircraft clipped it as it flew over the hill top. This was rare but not unknown in the F-111 community. When such 'accidents' did occurred, it was always at very low altitudes and under TF 'Hard' setting.

A volumetric RCS can have two Doppler components: from itself as a moving volume, and from the individual units. But if any unit is detached from the volume, its Doppler component will be lost to the seeking radar unless the radar is capable of distinguishing this unit in the first place.

Centimetric freqs can distinguish individual insects, even within a swarm, BUT only at a few hundred meters.

THE FEASIBILITY OF USING VERTICAL-LOOKING RADAR TO MONITOR THE MIGRATION OF BROWN PLANTHOPPER AND OTHER INSECT PESTS OF RICE IN CHINA - Riley - 2008 - Insect Science - Wiley Online Library

Translation: We can use cm and mm wavelengths to detect individual insects but only out (or up) to 240 meters. For the Brown Planthopper (BPH), each bugger weighs about 1-2mg and 2-3mm in body length. Using wavelength 3.2cm of the standard X band radar...

Radar - Wikipedia, the free encyclopedia

...We have an estimated RCS of 2x10-4 cm/squared at 200-300 meters distance PER BUG. Beyond this distance and the radar will have to rely upon the volumetric density of a BPH swarm to know if there are any BPH aflight. Millimetric freqs are better but this wavelength matches the diameter of individual rain drops. The result is that a mm wavelength signal will be intercepted by rain drops or anything similar before the signal can pick up any bug. This is why the mm wavelengths are usually confined to laboratory and/or highly specialized detection schemes outside of military applications.

The X band is centimetric but it does not matter the radar perspective, up or down looking, the distance involve between radar and aircraft renders the F-22 extremely difficult to create any statistical analysis by the seeking radar. As if looking up is not bad enough, there is the proverbial 'double whammy' if the radar is in a 'look down' perspective in that: Not only must the radar deal with a volumetric density that could be dismissed by itself but also that this volume's RCS is part of the 'ground clutter' rejection threshold.

Clutter is from radar echoes. Noise is NOT clutter, is independent of clutter, can exist without clutter, is hardware related, and is usually affected by time and temperature. Clutter + Noise = Interference. The F-22's RCS signal level is well within the clutter rejection threshold OR internally generated noise. So even if there are no flock of birds or swarms of insects around, odds are excellent that a radar system's own noise already blanket the F-22. The argument that the F-22's Doppler component will give it away despite its 'insect' or 'bird' level RCS came from a flawed understanding of radar detection, clutter types, and noise.

Still think you can detect the F-22?


No radar signals detect any 'shape'. The entire paragraph is absolutely nonsensical.


They did not waste any billions because they did not know how to build a 'stealthy' one.


Yes...We should.


Does not matter if it was NATO. An irrelevant argument.


No one claimed so.


Because the Iraqi air defense was not so fortunate? Fortune and probability are not the same thing.


Who said anything about using fortune as a basis for defense? Again...Fortune and probability are not the same thing. This argument is based upon a flawed understanding of fortune versus probability.


Nonsense. Currently, once a SAM is in flight, all an aircraft can do is evade, not try to shoot the missile. Perhaps what you mean is that the launchers would be destroyed? This argument ignored history, particularly the North Vietnamese air defense networks.


By this logic, all soldiers should be superb marksmen, one-shot-one-kill. After all, if a soldier need to shoot off several rounds to increase his odds of hitting his target and with no guarantees to boot, it is not worth the effort of shooting.


The US never claimed it was. This is a weak argument in trying to downplay the its effectiveness.


Probably...??? This is called a 'bi-static' radar configuration. Some air defense training call it 'electronic bracketing'. Your usage of the word 'behind' is indicative of a highly speculative argument. In a bi-static configuration, the reflection off a body that is from another transmitter is used by a physically and geographically distinct receiver to determine if the target produced a valid return. There is no 'behind', only approach direction. The catch for an effective bi-static radar attack, or bracketing, is that both stations must be in sync with each other as to when the transmitter will go active, its transmit freq, and the direction of the transmit.

The radar cross section (RCS) valuation of any body is essentially a 'fictitious' argument. This valuation is a 'fiction' in the sense that if no radar then no RCS. If the distance changes, then the RCS value changes. Same for freq employed, or transmit mode, such as pulsed or continuous wave (CW). The bi-static RCS of any object is always greater than its mono-static RCS but this assume that the F-117 was ALREADY under radar capture and its bi-static RCS is being used for greater odds of a successful SAM intercept. This is too much of an assumption that we cannot take it at face value.


You need to clarify the context of the word 'target' here. From an air defense perspective, the 'target' is an attacking aircraft. From the attacking aircraft's perspective, the 'target' is whatever on the ground that has some value. Lack of proper context rendered this argument worthless.


After several attacks it would be a 'no brainer'. Nothing spectacular from the Serbian air defense here.


This has been established. Still no 'Wow' factor here.


Guidance beam? This is still under the assumption that the F-117 was detectable in the first place. Too speculative.


Probably? We need something more concrete. Else the default position is -- no.


The 'luck' here is not about how the Serbian air defense was able to exploit NATO's predictability, although it is commendable that they did. The 'luck' here is that several missiles were launched and one of them successfully damaged the aircraft. The tactic is not new and is called 'spray and pray'.


Utter BS. Wild Weasels continued to harass the Serbian air defense at within SAM range. If whatever it was that Zoltan Dani did to make it so effective against the F-117, it should have been a hundred times more effective against these Wild Weasels fighters. The UAV combat loss is nothing more than red herring argument.


The air campaign did what it was supposed to do -- control the air space. To defeat the Serbian military it would have required a ground campaign. The dispute is not about whether the Serbian air defense was successful or not. The dispute is about the ridiculous claim that the F-117 was effectively detected, tracked, and targeted.


Sounds like a fail fail fail argument for the Serbian air defense to me.


This is a political argument.

You do ofcourse know that in Academia, we conduct statistical analyses of noise in communication systems to detect kryptography right?

 

[gambit]

You do ofcourse know that in Academia, we conduct statistical analyses of noise in communication systems to detect kryptography right?

Let us try this again...

Clutter is not noise and noise is not clutter. Clutter is external. Noise is internal. Clutter is a product of radar echoes (external). Noise is from hardware imperfections (internal). Clutter + Noise = Interference.

Next...

We know that corner reflectors are bad for any body that need to avoid radar detection. Corner reflectors amplify a body's RCS...

Corner reflector - Wikipedia, the free encyclopedia

Such devices are often used as radar targets or markers and are often employed on ships and, especially, lifeboats. These normally consist of three conducting metallic surfaces or screens perpendicular to one another.

Corner reflectors can also occur accidentally. Tower blocks with balconies are often accidental corner reflectors for sound and return a distinctive echo to an observer making a sharp noise, such as a hand clap, nearby. Similarly, in radar interpretation, an object that has multiple reflections from smooth surfaces produces a radar return of greater magnitude than might be expected from the physical size of the object.

This effect occurs regardless of object's physical dimensions and impinging wavelength. What we call 'ground clutter' is actually quite more from the many corner reflectors accidentally created by flora than from the Earth itself and this statistical distribution is not uniform. Now all one has to do is imagine and substitute, from the above images, leaves for flight control surfaces. Can any computer model guesstimate how many corner reflectors are there in a shrub from the many angles of the leaves in relation to each other? How about a forest in a storm? Now we have corner reflectors appearing and disappearing according to the wind.

Since noise is usually hardware related it can be controlled and factored in because we built the hardware and that we know its weaknesses and flaws, therefore noise can be seen as characteristic of a closed loop system. But not so with clutter. Statistical clutter modeling can be done but its complexity and outliers increases with sampling size. The sample here is the beamwidth and we know that beamwidth increases with distance between the radar and the ground, assuming we are in a 'look down' perspective.

I have never failed to illustrate this point with a variable focus beam flashlight analogy, like the type that made Maglite famous. Take a Maglite flashlight and position yourself atop a flight of stairs. Create the tightest focus you can at one meter altitude. Remain in place but slowly 'walk' that point of light down the stairs one step at a time. You will see the circle of light widens and the light become more diffused with each descent, or increasing distance (altitude) between the light and each step. That circle of light is a clutter sample. The smaller that sample, the more uniform the radar ground clutter echoes, the better we can discriminate and isolate a spike that could come from a metallic surface. Widen this sample and we will -- not may -- see a decrease in uniformity. The problem is obvious -- dynamic range. Not only of the unknown and accidentally created corner reflectors but also of their distribution as the sample size increases. Or as altitude increases as the seeker want volume search in lieu of resolution. Bad idea when he knows there is a hostile and low radar reflective enemy down there somewhere.

The F-22's RCS put it well into the dynamic range of most clutter rejection thresholds of most portable radars in the world. In a 'look down' perspective, we know that most fighter radars already have difficulties discriminating cooperative targets but they simply do not have the processing power and memory to model hundreds or thousands km/square of ground to look for a non-cooperative target. Bad weather will be the F-22's best friend for hiding it amidst the variable ground clutter.

You can control and filter out noise. But do you really want to filter out clutter when you know there is a flight of F-35s on the way? Does it really matter? Is your will up to date?

 

[CAPTAIN AMERICA]

Sorry for barging in like this but the fact remains clear that" America has never been a trust worthy ally" No grandiloquence based on personal affiliations or views is going to alter the history or mold present & future accordingly as one desires. "Disenchated Allies" by Seth Seifman is worth reading for those who are interested in the history of US-PAK relations.

I am sorry to say this and it will most likely get me banned again, but as an american being an allie over the years with Pakistan has been hard to stomach. Religious Extremism , honor killings, sharia law, Extremism, blasphemy laws, does this ring a bell ("Kill three million of them," said President Yahya Khan ), dictators, human rights issues, Pakistan is considered on of the top ten worse in the world.
Observer human rights index | Special reports | guardian.co.uk

Two other things, the F22 is not meant to be in a dog fight, if it does its job right, it will never be seen and never close enought to another plane to be in a dog fight. The second is the Chinese Anti ship Missile the Dong Feng 21D is a present missile that the Chinese have that armed with a nuclear war head could sink an aircraft carrier or would be as useful and accurate as any other missile, but as of this date has never been tested against a moving target.
http://www.foxnews.com/scitech/2010/08/06/chinese-carrier-killer-missile-game-changer-expert-says/

 

[muse]

Thank you captain - thanks for the truth - alliance between US and Pakistan is simply a lie.

 

[amalakas]

Let us try this again...

Clutter is not noise and noise is not clutter. Clutter is external. Noise is internal. Clutter is a product of radar echoes (external). Noise is from hardware imperfections (internal). Clutter + Noise = Interference.

Next...

We know that corner reflectors are bad for any body that need to avoid radar detection. Corner reflectors amplify a body's RCS...

Corner reflector - Wikipedia, the free encyclopedia

This effect occurs regardless of object's physical dimensions and impinging wavelength. What we call 'ground clutter' is actually quite more from the many corner reflectors accidentally created by flora than from the Earth itself and this statistical distribution is not uniform. Now all one has to do is imagine and substitute, from the above images, leaves for flight control surfaces. Can any computer model guesstimate how many corner reflectors are there in a shrub from the many angles of the leaves in relation to each other? How about a forest in a storm? Now we have corner reflectors appearing and disappearing according to the wind.

Since noise is usually hardware related it can be controlled and factored in because we built the hardware and that we know its weaknesses and flaws, therefore noise can be seen as characteristic of a closed loop system. But not so with clutter. Statistical clutter modeling can be done but its complexity and outliers increases with sampling size. The sample here is the beamwidth and we know that beamwidth increases with distance between the radar and the ground, assuming we are in a 'look down' perspective.

I have never failed to illustrate this point with a variable focus beam flashlight analogy, like the type that made Maglite famous. Take a Maglite flashlight and position yourself atop a flight of stairs. Create the tightest focus you can at one meter altitude. Remain in place but slowly 'walk' that point of light down the stairs one step at a time. You will see the circle of light widens and the light become more diffused with each descent, or increasing distance (altitude) between the light and each step. That circle of light is a clutter sample. The smaller that sample, the more uniform the radar ground clutter echoes, the better we can discriminate and isolate a spike that could come from a metallic surface. Widen this sample and we will -- not may -- see a decrease in uniformity. The problem is obvious -- dynamic range. Not only of the unknown and accidentally created corner reflectors but also of their distribution as the sample size increases. Or as altitude increases as the seeker want volume search in lieu of resolution. Bad idea when he knows there is a hostile and low radar reflective enemy down there somewhere.

The F-22's RCS put it well into the dynamic range of most clutter rejection thresholds of most portable radars in the world. In a 'look down' perspective, we know that most fighter radars already have difficulties discriminating cooperative targets but they simply do not have the processing power and memory to model hundreds or thousands km/square of ground to look for a non-cooperative target. Bad weather will be the F-22's best friend for hiding it amidst the variable ground clutter.

You can control and filter out noise. But do you really want to filter out clutter when you know there is a flight of F-35s on the way? Does it really matter? Is your will up to date?

I didn't say that, I said that it is possible to hide a signal within and well below noise thresholds, and by conducting an analysis on the noise, it is possible to pick it up.
I was merely suggesting that there is a way to pick up a "non-cooperative source" of reflection if it is hiding below a given threshold.

I never suggested that there is a working system that can do that, all I am saying is that the mathematics that can do it sort of exist...

 

[amalakas]

I am sorry to say this and it will most likely get me banned again, but as an american being an allie over the years with Pakistan has been hard to stomach. Religious Extremism , honor killings, sharia law, Extremism, blasphemy laws, does this ring a bell ("Kill three million of them," said President Yahya Khan ), dictators, human rights issues, Pakistan is considered on of the top ten worse in the world.
Observer human rights index | Special reports | guardian.co.uk

I am sorry to have to ask that Captain, but I find this a rare occasion..

Greece has none of the above, and is officially an "ally" and to be honest one that has "bent over" for the US a large number of times...

why oh why has the US never really supported Greece in anything in a real and meaningful way? Cyprus, Aegean, FYROM, just come to mind....

just a question ....

 

[Myth_buster_1]

I am sorry to say this and it will most likely get me banned again, but as an american being an allie over the years with Pakistan has been hard to stomach. Religious Extremism , honor killings, sharia law, Extremism, blasphemy laws, does this ring a bell ("Kill three million of them," said President Yahya Khan ), dictators, human rights issues, Pakistan is considered on of the top ten worse in the world.
Observer human rights index | Special reports | guardian.co.uk

Hypocrisy at its best.
So tell me what you have mentioned does not happens in India? Religious Extremism = Hindus killing muslims, christens.... Honor killings seriously i dont even hav time to mention what kind of world's biggest democracy india is... You need to be enlightened how women in india are treated like trash.
Btw, extremism did not exist back in 90s when f-16s were embargoed. So does america only supply f-16s to pak for supporting extremism? lol
killed three million? ooo found any mass graves or ????
And do you want to know how many innocent civilians in millions have been killed by american unjustified wars?

 

[INDIAN007]

u been to INDIA ???????

 

[CAPTAIN AMERICA]

I am sorry to have to ask that Captain, but I find this a rare occasion..

Greece has none of the above, and is officially an "ally" and to be honest one that has "bent over" for the US a large number of times...

why oh why has the US never really supported Greece in anything in a real and meaningful way? Cyprus, Aegean, FYROM, just come to mind....

just a question ....

So you think the USA should go to war with Turkey over Greece, I am not sure of the point.

 

[CAPTAIN AMERICA]

Thank you captain - thanks for the truth - alliance between US and Pakistan is simply a lie.

More like a necessary evil.

 

[amalakas]

So you think the USA should go to war with Turkey over Greece, I am not sure of the point.

Not at all..

How about equal treatment between Turkey-Greece when it comes to international law..

How about not lobbying in support of FYROM (which by the way have completely ridiculous and unfounded claims) just to promote US foreign "hidden agendas" in the balkans since that lobbying is hurting a "traditional ally" such as Greece..


How about offering the same FMS funds for the same piece of equipment as to other countries (e.g. UAE, Turkey)
i.e. Turkey and UAE pays less for the same equipment than we do....
and yet when we try to choose non-american equipment, we are then blocked and lobbyied off of it, so we end up buy american for more...

How about not issuing Warnings for Greece being an "unsafe" place for american tourists every single year for the last 30 or so years while the surrounding to Greece countries are equally or more dangerous (if at all)

see, there is a bunch of things that can be done for an ally instead of going to war..

and to be honest, Greeks have always fought their own battles at terrible cost.. terrible... we don't need someone else to fight our battles when these come up.. we usually fight to the man.. as we have always done...

but we like our friends to be friends... and not pimps...

clearly none of this is your fault, or you should be knowledgable about them, but since you spoke about PK, I thought I'd ask...

 

[Muhammad-Bin-Qasim]

I am sorry to say this and it will most likely get me banned again, but as an american being an allie over the years with Pakistan has been hard to stomach. Religious Extremism , honor killings, sharia law, Extremism, blasphemy laws, does this ring a bell ("Kill three million of them," said President Yahya Khan ), dictators, human rights issues, Pakistan is considered on of the top ten worse in the world.
Observer human rights index | Special reports | guardian.co.uk

Two other things, the F22 is not meant to be in a dog fight, if it does its job right, it will never be seen and never close enought to another plane to be in a dog fight. The second is the Chinese Anti ship Missile the Dong Feng 21D is a present missile that the Chinese have that armed with a nuclear war head could sink an aircraft carrier or would be as useful and accurate as any other missile, but as of this date has never been tested against a moving target.
FOXNews.com - Chinese 'Carrier-Killer' Missile Could Reshape Sea Combat

Not commenting on the rant part of the above post... I would say that once America fails to pay the Chinese the billions of dollars it owes to that country and tries to go to war with it... we may just find out if that missile works or not...

 

[mehboobkz]

I would say that once America fails to pay the Chinese the billions of dollars it owes to that country

What is that money? those billions that US owes?

 

[Chogy]

I would say that once America fails to pay the Chinese the billions of dollars it owes to that country

What is that money? those billions that US owes?

The Chinese own a large number of U.S. Treasury bills - think savings bonds, or similar. They can be purchased on the open, international monetary market.