Nop, it measures the difference in Phase on the incident signal at an instant between 2 elements distant of a fraction of the wave lenght. AESA radar actually use that very technic to resovle the bearing. the phase difference is resulting from the signal delayed arrival between the 2 elements, hence having an instaneouss difference in phase measured between the 2 elements. this is 101 phase interferometry.

Phase interferometry makes, amongst other , the assumption that the signal wave are paralell and emitter at infinite .That assumption create calculation error that get worse as distance to emitter decrease, where signal waves get less and less paralell like. Anyhow the error in calculation from both assumption and other aspect has been demonstrated to be proportional to the inverse of range . so the longer the range the lesser it corrupt the result of calculated AOA.

Given AESA radar and RWR inferometer use the same technic , same magnitude in precision should be expected .Advantage to the radar though who controls the emission and thus the wave lenght and is specifically tunes to that on the receiveing side.

A2G does not change anything in term of bearing accuracy or not , it change all in term of range as the AOA intersected with a ground map will give you the coordinate and range. Fact the target is static or not does not change anything to the measured bearing, not even to its incertitude. The bearing still allows to cue a presision weapon ( metric ) at distance .

I’m aware of that but at the actual sensor level, how is phase measured? It’s measured based on signal amplitude difference between the two elements because there is no way to directly measure phase. A radar has way more elements and is larger, which greatly reduces error. See page 5-8.8, last few paragraphs.

http://www.phys.hawaii.edu/~anita/new/papers/militaryHandbook/sig-sort.pdf

Ah yes, it actually does, because you need a right angle to use the trig. My apologies. However, I would argue that at ranges of 20+km the error of that approximation is continually small, because the distances are huge compared to element separation. And hence, in absolute terms, whilst the % error may be marginally smaller at distance, the absolute error will be larger in terms of offset distance of actual target relative to that measured. Interestingly the Typhoon’s DAS claims 1deg accuracy at 100km.

Nope, see above. The radar has more elements a greater distance apart and has a measure bearing accuracy of circa 1 milliradian. The same thing that allows larger radars to make a narrower beam, also makes bearing detection more accurate.

Err no, but it does make the whole issue of range and velocity calculation way easier. It’s also a much easier target, especially if your missile has a passive radar seeker. So hitting a SAM radar is really nothing remotely like intercepting an aircraft doing 600mph.

No-one signs to the Official Secrets Act. What you sign is an acknowledgement that you have been informed of the provisions of the Act.

And the provisions of the Act apply to everybody. That is why the journalists involved in the ‘ABC’ case found themselves in dock and facing the prospect of going to jail. They had gathered classified information with the intention of passing it on the persons not cleared to receive it, i.e. their readers.

In practice, modern juries are most reluctant to convict under the Official Secrets Act. In the last case that I can recall, the jury returned a Not Guilty verdict against an MoD employee who had leaked the deployment date of the GLCM system.

How’s that for a sweeping generalisation!

I would rephrase it thus:

The old ‘classified’ ruse is sometimes used by people who wish to claim capabilities that don’t to the best of their knowledge actually exist. That doesn’t mean the capabilities don’t exist, it only means that the poster doesn’t have any evidence one way or the other.

But I would also postulate:

A forum poster who is in possession of facts that are classified, rated ‘unclassified sensitive’, are covered by other restrictions such as the Chatham House Rule, or which the poster feels should not be in the public domain, can either not post on subjects on which this knowledge is relevant, or post only carefully-worded and limited information.

Of course, the problem for forum readers is having to work out into which category a specific forum member falls. Track record is the only answer, I think.

Given that I have never (to the best of my knowledge) posted such a claim, and having no opinion on the matter, I can only suggest that you pass that question to the Society for Psychical Research.

Semantics…

You can only be prosecuted if you’ve been made aware that the information you’ve received is classified, and then only way to prove that is with a signature.

Well that argument fails too, given the journalist who mentioned it.:highly_amused:

Well my premise is as follows: Using a fundamentally less accurate form of geolocation and velocity measurement for the sake of remaining passive, only to transmit said measurement non-passively seems somewhat futile.

the 11.5 tn might refer to the two seats configuration. Regarding speed I believe that 20 or 30 years ago they would state something like 2.2-2.4 maybe even 2.5, but nowadays it doesn´t make much sense. the RAF 1.8 figure probably refers to very specific RAF configuration for peace time to reduce airframe and engines fatigue. Most sources states 2+ which basically means it has power to fly at a speed in excess of mach 2 but its not recommended to surpass such speed as doing so would be very demanding for the airframe (composite materials and speed…), I think that mig25/31 was similarly limited to 2.8 and even F22 is probably limited to 2.2-2.4 to preserve its RAM coatings…

MiG-31 is limited to M1.5 right now.

Obviously speed depends on config. and there are recommended limits but also emergency limits (real limits), which are certainly over M2.0 and probably near the M2.35 figure given two AFs have stated that and the maths works out to that based on DA2 achieving >M2 with RB199s.

This suggests M2.35 at 36,000ft.

http://www.bundesheer.at/waffen/waf_eurofighter.shtml

Yes. Of course but he was mentioning relative precision.

If e is the precision over A then e will be also the precision over A/10 (sensor characteristic)

Let’s say that e/A=r then e/(A/10)=10*(e/A)=10r
Relatively,the precision affects 10 times more a measured distance at 1/10th the range.

Are we still talking about range or bearing measurement using phase interferometry?

The basic calculation is:

Now as the point moves closer to the Rx, d becomes larger relative to the distance and the phase difference also becomes larger, hence the scope for inaccuracy given the same measurement errors is mathematically lower. This can easily be seen by taking a point on the rightmost line and moving it to and from the antenna and approximating it as a right angled triangle. If d = 1 (arbitrary units) and length along second line equals 5, then the hypotenuse is 5.1 (0.1 longer). If length is 10, then hypotenuse is 10.05 (0.05 longer), so phase difference is smaller and measurement accuracy is more crucial. The angle between the length and the hypotenuse is also getting smaller with distance, so range calculation becomes more difficult. As the length moves to infinity, the phase difference will indeed tend towards zero (as the lines will be parallel) and the calculation will become impossible.

This is also borne out to some degree because the AN/ALR-94, widely believed to be the best RWR (at least prior to the ASQ-239 maybe) is only accurate to 2deg at 450km.

https://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor#Avionics

Any methods include error . DF via phase interferometry AOA resolution is actually far more accurate than TDOA method and as mentioned said to give a bearing with less than 1 deg incertitude with the most basic setup. I guess the important thing here is in the less than 1 deg . As mentioned earlier the calculation error being inverse to the range the longer the range the less the error weigh on the results so 1 deg would be the maximum incertitude at useful range . Note that the method is used to extract target coordinates for A2G precision weapons, so the bearing is not too shabby. Here the range being easier to compute since target is static and on the ground.
I am not too sure why your are talking about amplitude and TDOA here along phase interferometry.
Anyway comparing on bearing measurement performance , one would have to know the incertitude associated with IRST bearing measurements according range too.
So I am not sure how you can conclude the IRST being much more effective in absolute ( no range notion) ,this not only on bearing , but on geolocation altogether .

Yes but phase interferometry is still attempting to measure the phas of a wave at two points. There is no way to do that directly, so it has to use the amplitude at those two points vs the pk-pk value. The latter can only be based on the last peaks and the signal strength is changing as the aircraft move. You also have the issue of pulse compression algorithms and AM thrown into the mix.

At long range the accuracy will be worse in absolute magnitude not better, because you have the same error applied to a smaller extended angle.

A2G is different, since the target is static and the ground is in a much more well defined position, therefore the angle pretty much gives the range away.

How do you measure the phase at two points? That’s why I mention it. No such thing as a phase-o-meter.

Well radar gives accuracy to a milliradian (0.057deg) and IRST is more accurate. So that makes it at least an entire order of magnitude better on bearing than RWR, even if range is slightly less accurate, which it may or may not be.

Remind me again who formed an alliance with Nazi Germany and launched an unprovoked invasion of Poland and the Baltic States. :confused:

Let me guess, another chapter that somehow got misplaced for your history books as a child?

[ATTACH=CONFIG]248505[/ATTACH]
Some of the 22,000 victims of the Katyn massacre, murdered by the “never brutal” Russians.

https://en.wikipedia.org/wiki/Katyn_massacre

:rolleyes: This is obviously becoming pointless. Czechoslovakia, Hungary, Poland, the Baltics, the South Caucasus, how many states on Russia’s periphery have experienced the “not brutality” of a military invasion by Russia?

Let me know next time you see American tanks rolling down the street in Ottawa because we didn’t like their last election.

Let me know next time you see the US building walls to keep people from fleeing or murdering people trying to escape our “not brutality.”

Etc etc

It’s been argued that NKVD massacres actually started WWII.

Certainly the only person to have killed more than Stalin was Mao.

As I explained in posting #98, to provide such a capability in a Standard-sized missile would require near-impossible levels of missile performance, a fact that at least one Russian high-level official has admitted “off the record” to his US counterpart. So it only becomes an issue if the Russians believe that the US defence industry is capable of producing near-magical increases in rocket-motor performance.

But would the SM-3-IIB fit the existing launcher? What was its diameter? Even if it was secretly revived, how many years would be needed to go from first flight (the first public acknowledgement of its existence) to deployment?

You could equally well argue that Russia might be developing a new mobile Pioner-class IRBM under a black programme.

The diameter was 27 inches, which doesn’t currently fit a Mk41 naval VLS, but I can’t speak for the land-based system, assuming it isn’t the same, which it may be.

The IIA is capable of 1500km altitude, so a 27 inch version with 65% more fuel probably could reach 2500km altitude.

Indeed you could, difficult to know. I personally think the Iskander-M offers more than the stated 500km range but that’s just a personal assessment and nothing more.