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Subject: Rafale Proves Itself
SYSOP    8/7/2011 7:59:23 AM
 
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BWisBack       12/14/2011 11:29:47 AM
Herald :
""Can a French DRFM jammer operate on multiple frequencies simultaneously first? ""
 
Yes , definitely yes .
 
""Can it copy and replicate the multiple frequencies and clockmatch in real time?""
 
Yes , definitely yes .
 
""NO if it is SPECTRA""
 
? ... You know of a better system ? I don 't .
Now , if you want to go back years ago , I already nailed you on this matter . Wanna start all over again Herald ?
 
Cheers .
 
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heraldabc    Ah the sound of crickets...   12/14/2011 12:25:47 PM
Isn't it lovely?
 
H.
 
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Reactive       12/14/2011 1:11:40 PM
 For goodness sake BW, you don't post scientific articles that you even HALF understand, I posted one public domain article that discussed in broad terms the sorts of capabilities needed to DETECT a generic LPI broadcast, you didn't understand the article.
 
If you were clever you'd notice that nearly all the articles in the PD that talk about LPI countermeasures are actually only talking about statistical probabilities of DETECTING, not JAMMING the radar, and by detecting they don't EVER mean detecting the entire signal, only that there is one.
 
It is the processing advantage that really matters with LPI, I know you won't understand what that means.
 
Again, if you think SPECTRA is capable of doing this then you are simply using blind-faith or the power of the unknown, i.e. it can have any property so long as you refuse to understand anything. "If SPECTRA can't do active cancellation then surely it can detect and jam every radar in the world including those that are generations ahead of the latest french technology..." 
 
And that's not to say LPI is a magic cure-all, you still need a minimum energy return to generate a signal, which is why 5th generation craft without exception seek to reduce their RCS to an absolute minimum rather than trying to stay on the losing side of the energy battle.
 
 
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halloweene       12/14/2011 4:52:56 PM
@ reactive
I have no clue that spectra use -or not - AC. Jamming LPI radars seem a bit complicated, but what about missile radars?
 
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heraldabc       12/14/2011 5:34:04 PM


@ reactive

I have no clue that spectra use -or not - AC. Jamming LPI radars seem a bit complicated, but what about missile radars?

That would be okay if SPECTRA uses the appropriate radio bands to deceive; BUT.
 
 
Note the AMERICAN contribution?
 
H.
 
H.\
 
 
 
 
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BWisBack    @Reactive   12/14/2011 5:48:19 PM
You greatly underestimate me but never mind .
 
You said :
""If you were clever you'd notice that nearly all the articles in the PD that talk about LPI countermeasures are actually only talking about statistical probabilities of DETECTING, not JAMMING the radar, and by detecting they don't EVER mean detecting the entire signal, only that there is one. ""
 
You need to update your knowledge . Old ES receivers did not have the needed sensitivity to detect LPI signals as they were stuck to about -40dbmi when a minimal of -90/-100dbmi was requested . Now , we have multiple designs who goes below -100dbmi .
For example , chanellized receivers are far more sensitive than IFM receivers but there is other very capable systems like superheterodyne receivers or the acousto-optic receivers (Bragg cell) . These when coupled to digital receivers (using mainly FFT : Fast Fourier Transform) can not even detect LPI signal but can also do "finger printing" of the LPI signals .
There is a rather good number of receivers who can : detect , identify , classify and finger print LPI radars .
Some are based on HSMR or on the acousto-optic module (AOM) version with 2 GHz Bragg cells . A good number of these receivers are designed by Thalès .
I could go a bit more technical but it would get boring for most of us . Suffice to say that top notch RWRs are perfectly capable to detect , identify , classify and finger print LPI radars like the APG-77 . It is the reason why the USAF has always been very reluctant to use the F-22 against the Rafale BVR and never did so far . I can understand and I would have done the same . No need to give away to Spectra some of the techniques used by the -77 .
 
That is enough for now wrt detection , now what about jamming ?
C =W log2 (1+ SNR)
C is the channel capacity in bits/second, W is its bandwidth, and SNR is the signal to noise ratio. In this case, if W is set to 1 then C becomes the capacity in bits per interception . (Shannon 's theorem)
Starting from there , we can extract bits of informations from the LPI signal and play with it in real time . Some radars (like the FMCWs) are using "chaotic" waveforms and can be difficult to deal with but things are moving fast .
Here , one has to remember that the LPI radar wait for only a small portion of the emited signals to come back and build a picture from it . Well , that small portion WILL BE the jammed part ! Clever , isn 't it ?
 
So Reactive , as I said few years ago , LPI is not very much LPI nowadays ...
 
Cheers .
 
 
 
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heraldabc    Stolen from here by the way.   12/14/2011 5:57:36 PM
Source....

He still got it WRONG.

 

H.

 
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heraldabc    Stolen from here by the way.   12/14/2011 5:58:41 PM
Source....

He still got it WRONG.

 

H.

 
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heraldabc    Stolen from here by the way.   12/14/2011 5:59:08 PM
Source....

He still got it WRONG.

 

H.

 
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BWisBack       12/14/2011 6:03:45 PM
Yes Herald , as I said before it is better to use US papers on SP since no-one would beleive a French study .
I do what I said I was going to do .
And no Herald , I am not wrong .  Stop complaining and try to discuss in an adult manner please .
So , what YOUR view on the subject ?
 
Cheers .
 
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