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)
 |
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). |
 |
 |
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). |
 |
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
WADGPS and JDAM at SRI
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
USN JSOW Page
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
JSTARS Ground Station Module
DASA Airborne SAR
Sandia National Laboratories SAR (Excellent Imagery)
AMPS Synthetic Aperture Radar
NASA TOPSAR Imaging SAR
SAR Remote Sensing
DREO CSAR Project
Synthetic
Aperture Radar (SAR) Web Page
NAVSTAR GLOBAL POSITIONING SYSTEM
(www.spacecom.af.mil)
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
