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JDAM + AESA radar = radar guided bomb

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posted on Nov, 4 2005 @ 10:47 AM
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The JDAM "Smart Weapon" uses the APG-79 AESA radar to provide precise targeting coordinates. The pilot uses a high resolution SAR (synthetic aperture radar) image to identify the intended target. The target is designated from the image; the target coordinates are passed to the JDAM weapon; the weapon is released and flies under GPS navigation to impact, thus completing the kill chain. Prior to the introduction of the APG-79 radar, it has only been possible for pre-mission planned ground targets to be attacked. Now, with the Active Electronically Scanned Array (AESA) APG-79, real time, time sensitive ground targets can be identified and engaged.


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Wow, sounds pretty cool. I read that Space Radar will also have SAR, so not only will it be able to provide radar coverage over most of Earth but also imaging.




posted on Nov, 6 2005 @ 12:02 PM
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This would indeed speed up things.

I take it this is how jdam was able to hit a moving target recently?



posted on Nov, 6 2005 @ 08:23 PM
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Utter BS,

Any jet with a 1760A/B capable databus (1553B plus conditioned power) can 'talk to' a JDAM based weapon on the pylon.

Nor is the APG-79 (which is restricted to the later Lot-II Super Bugs) necessary for it's use to hit planned or unplanned targets.

What the AESA does, as part of the 'HART' or Hornet Autonomous Radar Targeting system is two things:

1. With a new radar data processor and onboard gyro, it allows the fighter to perform SAR mapping in a way that the APG-73 on all but the F/A-18D(RC) cannot match. In fact, the AESA's ability to act as a series of phase adaptive miniarrays improves the normal doppler based imaging resolution of fighter-SAR quite a bit.

2. Again thanks to it's ability to split array functions, the radar can /likely/ communicate with the GBU-38 HART bomb, 'on the fly'. This is almost certainly as a function of an upgraded (2-way) GPS transceiver on the weapon which functions in a manner similar to that of the AMSTE testbed bombs to improve weapon tracking of point/mobile targets.

Essentially then, the APG-79 is able to use ISAR or InSAR techniques to 'tune' the baseline large array behavior of the mapping function. Probably down to sub-1m levels. Overlay that capability with MTI if need be. And further track the bombs, in flight, to the target through a sideband datalink similar to that of the AMRAAM and other 'tethered' missiles.

So that the bombs fall to corrected coordinates with superior accuracy to that which is normally available thanks to 'stereo error' in the atmospheric anaprop transmission skews of the various GPS constellation feeds.

The sadness being that the original HART program was designed to integrate multiple sensors including the ATFLIR which would have /really/ improved targeting (angular errors of sub-milliradian levels with an on-pod gyro) but as I understand it, the USN cheaped their way out of it.

And this inhibits it's use in the CAS/OBAS scenarios for which small bombs dropped from close in are most useful.

CONCLUSION:
HART/GBU-38 has likely been superceded as a functional but not paradigm alterang weapons system by equivalent USAF efforts. Indeed, without the diamond back kit of the GBU-39 Small Diameter Weapon; the bomb just doesn't have the reachout to exploit any kind of standoff radar targeting advantage in avoiding multiple threat MEZ overlaps or defeating cross/head/ wind or coordinate elevation variables in complex targeting scenarios. At the same time, the JCM (Big Hellfire based on the AGM-114K) has superior multi-target/multi-designation capability to engage targets regardless of target folder source. And both are inferior in their carriage numbers (X2 each on the CVER or JCRL) to the USAF SMER with it's four-per-hardpoint capability that brings upwards of 16 weapons to the F-15E and probably 80+ to the B-2.

They will also likely be inferior on costs.

Basic GBU-38 (as recently employed by ANG F-16's) is a decent enough weapon. As a function of weaponeering it is simple to upload and removes the 80 flight hour limit on the GBU-12 between complete GCS tear down inspections. Even as it also throws out the weather factor on 2 eys on target and CBase effects.

Similarly, the APG-79 is the /only/ thing which makes the Bug-Deux worthwhile in the 'fighter mission', even if the use of a 2-seat airframe for what is now termed 'the Tomcat mission' (FADF), so close inshore, is just shy of hilarious.

But the fact remains that neither the weapon nor the sensor is unique in it's presented capabilities so much as 'convenient' in what they do to exploit existing, transitional, airframe systems. And both of them will be rapidly superceded once fighter-AESA becomes standardized in the JSF and JUCAS.

And multi-impact standoff point strike is the norm with SDB and Fast Hawk aeroballistics.


KPl.



posted on Nov, 6 2005 @ 10:56 PM
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Thanks for the explanation, ch1466!



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