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Will LPI radar be used to guide SAMs?



 
 
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  #1  
Old December 31st 03, 09:47 AM
Chad Irby
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Default Will LPI radar be used to guide SAMs?

In article ,
Hobo wrote:

This NG loves to talk about whether or not stealth aircraft can be
detected. What about the issue of detecting SAM radar? If LPI, or Quiet
Radar techniques are used on the ground radars guiding SAMs this will
make it difficult to find and destroy the radars.


The problem with LPI is that most of them are just very low power,
continuous-wave radars with a huge chunk of signal processing gear
tacked on. Smaller output, harder detection, right?

Except that defensive measures are getting better, too, for the same
reasons, and with that low power, jamming becomes much easier. And if
you get the power low enough, a cheap, disposable white-noise jammer
takes the whole thing out of the equation (most LPI sets are pretty
darned close to the noise threshold to begin with, which is what makes
them hard to detect).

Even with frequency hopping or broadband techniques, you're still
broadcasting a signal of *some* sort, and the smarter ECM systems will
still find you.

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.
  #2  
Old January 2nd 04, 03:19 AM
The Enlightenment
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"Hobo" wrote in message
...

I tried asking this question before and got zero responses;(


This NG loves to talk about whether or not stealth aircraft can be
detected. What about the issue of detecting SAM radar? If LPI, or

Quiet
Radar techniques are used on the ground radars guiding SAMs this

will
make it difficult to find and destroy the radars. Similarly, if the

same
pseudo-random noise techniques are used for the datalink the SAMs
guidance will be harder to jam.

If one cannot bomb SAM radar or jam the datalink than flying in

enemy
airspace becomes vastly more difficult. The basic ideas behind LPI

radar
seem to come from the same information theory behind much of the

cell
phone industry so the knowledge base is widespread.



Most modern SAM guidance techniques are heading towards an active
homing system. The French have a common active hommer on the AAM
mica and the SAM aster. The SAM is launched preloaded with the
co-ordinates and velocity of the target and the missile guides itself
using an inertial guidance system to the vicinity of the target at
which point the radar lights up. Usually a data link is also
available for midcourse corrections. In the case of AMRAAM there is I
believe only 1 midcourse update provided if at all.

In this way:
1 The command link can be of low bandwidth and is easily given the
characteristics of security and LPI. It is not neccesary to provide
feedback to the missile since it has an inertial guidance system.
2 Little warning is given since there is no tracking and illuminating
radar 'spiking' the target.
3 Jamming and stealth against the missile is less effective as the
radar's illuminating power increases as the missile active radar
approaches.
4 Multiple missiles can be launched.

The next stage of radar appears to be impulse radar. This AFAIKS
requires cryogenics. It consists of sequences of impulses of around 1
wavelength that contain broad spectrums of frequencies that can excite
any resonance's within a stealth structure. It also is extremely
capable of resolving chaff or terrain like ocean waves and ripples.


  #3  
Old January 2nd 04, 06:19 AM
Denyav
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The problem with LPI is that most of them are just very low power,
continuous-wave radars with a huge chunk of signal processing gear
tacked on. Smaller output, harder detection, right?


As long as you use radar,or any kind of EM energy as a binary detection
method,right.
But if you start processing,for example, polarimetric data,you can easily
seperate signals reflected by man made objects from the others.
  #5  
Old January 3rd 04, 02:41 AM
Denyav
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And signals of any polarization are easy enough to generate with jamming
equipment, so if you're relying on that, you've got to worry about being
spoofed.


So,ECM,predicted to be dead after arrival of stealth platforms are "in" again.
  #7  
Old January 4th 04, 09:02 PM
Chad Irby
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In article ,
Hobo wrote:

Great. Now what if the SAM radar is undetectable?


No such thing.

If it emits, it's detectable.

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.
 




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