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The F-111 Aardvark at Website is proud to host:

The GPS Guided Weapons Page

Incorporating the SAR/GMTI Radar Page

(c) 1996, 1997 Carlo Kopp (Background Profile)


Last Updated 7 June 1997

We are currently about to enter a new era in air power, as significant in its impact as the deployment of the laser guided bomb and the thermal imaging laser designator. The central technology in this paradigm shift is GPS, which confers all weather accuracy in wholly autonomous weapons.

While the use of GPS for bomb guidance has won wide acceptance in the US, with the USAF and USN intending to replace the Laser Guided Bomb with GPS guided bombs and glidebombs, the technology has yet to gain wider acceptance in other Western countries, Australia being no exception.

To fully exploit the potential of GPS guided bombs, a sensor is required with matching all weather capability and standoff range. This sensor is the high resolution imaging Synthetic Aperture Radar (SAR), often also capable of Ground Moving Target Indication (GMTI). We are now beginning to see the second generation of attack radars with such a capability. These are typified by the B-2A's Hughes APQ-181, the Norden APG-76 used in the Israeli F-4E upgrade, the Hughes APG-73 used in the F/A-18C and late models of the APG-70 used in the F-15E Beagle. The current state of the art in this technology indicates that SAR spot imaging can be performed with resolutions as fine as 1 ft at tens of nautical miles, cutting through any weather. GMTI capabilities in such radars range from the detection of vehicles, up to the recognition of rotating radar antennas, vehicle types and hovering helos.

The way of the future are strike aircraft equipped with such radars, dropping GPS inertial guided gravity and glide bombs. This capability confers the ability to attack multiple separate targets with LGB like accuracy in all weather single pass attacks. There is no need to wait around to lase the target, as the weapons are completely autonomous once pickled off.

In the context of the F-111, if fitted with such a radar and carrying up to six JDAM or AGW weapons (4 x external, 2 x internal) it could engage four to six aimpoints on a single pass with an arbitrary cloudbase. Once the weapons are released, the aircraft can immediately egress the target area.

This web page is intended to stimulate professional debate on this subject. To that effect, it will gradually accumulate trade journal features on this and related subjects, as well as other related links of interest. Please enjoy the ride !

Articles hosted at the Web Site

GPS Guided Weapons Part I (AA August 1996)

GPS Guided Weapons Part II (AA September 1996)

GPS Guided Weapons Part III (AA October 1996)

GPS Guided Weapons Part IV (AA December 1996)

The Agile Gliding Weapon (Aussie Glidebomb) (AA June 1996)

More of Carlo's published articles can be found here.

SAR/GMTI Imagery (Northrop-Grumman (Norden) APG-76 MMRS)

APG-76 Image #1 The APG-76 MultiMode Radar System was designed and produced by Norden, now a division of Northrop-Grumman. It is operationally deployed as an attack radar on the F-4E of the IAF, and under evaluation in the US. This series of pictures depicts shipping which is being imaged by the APG-76 in spotlight SAR mode. This first frame shows a surface vessel detected at 40.1 NMI, the resolution of the 0.8x0.8 NMI box is 10 ft (photo Northrop-Grumman).
Closing in on the target, at 32.3 NMI the radar mode is selected to 3 ft resolution spotlight SAR. Note the shape and fine features of the target are far more pronounced (photo Northrop-Grumman). APG-76 Image #2
APG-76 Image #3 At 29.6 NMI the radar mode is selected to 1 ft resolution spotlight SAR. At this resolution you could select a specific aimpoint on the target for weapon delivery. Or identify the target precisely (photo Northrop-Grumman).
This image of a coastline was taken by an APG-76 running in SAR 2.5 mode from 28.9 NMI, with a 30 ft resolution. The white rectangles are an LCAC landing craft and amphibious vehicles detected by the GMTI mode of the radar. The combination of SAR and GMTI strips away the cover of darkness and foul weather which would otherwise allow surface targets to evade air attack (photo Northrop-Grumman). APG-76 Image #4

Related Links

McDonnell Douglas Joint Direct Attack Munition

Texas Instruments Joint Stand Off Weapon

USAF Miniaturized Munition Technology Demonstration Branch (Small Bomb)

USAF EDGE DGPS Guided GBU-15 Tests


USAF JDAM Program Office

USAF Wide Area GPS Enhancement (WAGE)

Boeing AGM-86C CALCM

Rockwell GPS for JDAM

Rockwell GPS Receivers

Hughes (formerly Magnavox) GPS Receivers


Northrop B-2A GAM/GATS Weapon System

Hughes APQ-181 Multimode LPI Radar

Hughes APG-70 Multimode Fire Control Radar

Hughes APG-73 Multimode Fire Control Radar

Hughes ASARS 2 (Advanced Synthetic Aperture Radar System)

Hughes HiSAR


JSTARS Ground Station Module

DASA Airborne SAR

Sandia National Laboratories SAR (Excellent Imagery)

AMPS Synthetic Aperture Radar


SAR Remote Sensing


Synthetic Aperture Radar (SAR) Web Page


Navstar GPS Internet Connections (Many Good Links)

Links to GPS sites (UCSD)

DGPS Technical Papers (Differential Corrections, Inc.)

Wide Area DGPS (WADGPS) at Racal

GPS World Online Magazine

Halting the Advance: The Synergistic Effects of Heavy Bombers and Carrier Air LOGO


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