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Sensor characteristics include grazing angle of 12 degrees (6 degrees for ground moving target indication -GMTI), slope angle of 70 degrees, and squint angle of 45 degrees (no squint angle for GMTI). SAR collection can only occur in one "wing" of the "butterfly" ground coverage area at a time, antenna slewing is required to image in the other "wing." Synthetic aperture radar was selected to provide day/night all weather collection capability. In strip map SAR mode, DISCOVERER II provides 3 meter impulse response (IPR) imagery at a collection rate of 700,000 km2 per hour. Such collection would typically be used for object detection, to cue collection in other modes or using other sensors for classification and/or identification.
· In scan SAR mode, DISCOVERER II provides 1 meter IPR imagery at a collection rate of up to 100,000 km2 per hour. Such collection would typically be used for object classification.
· In spot SAR mode, DISCOVERER II provides up to 160 images per hour at 0.3 meter IPR of 4 km x 4km target areas. Such collection would typically be used for object identification
In GMTI mode, DISCOVERER II provides 3 meter target location error at a collection rate of 2,000,000 km2 per hour for object detectable velocities between 1.3 and 58 knots.
DISCOVERER II SAR imagery taken over a period of several hours or days of a particular assembly area, when subjected to Coherent Change Detection processing, may show changes in levels of activity for forces based in that general locale. GMTI data will also indicate relevant military activity through indications of traffic flow and movement into and out of known or suspected areas of operation. This data would be used to cue unmanned aerial vehicles (UAVs) or other airborne and national sensors for vehicle/target identification and classification, for purposes of interpreting the opposing commander's intent. The DISCOVERER II high-revisit-rate feature, wide area coverage, and on demand assured access SAR capability could reduce the tasking on national and theater assets, to increase their effectiveness in collecting targets of a strategic nature.
Signals Intelligence (SIGINT) platforms may indicate a potential for vehicle movement into or out of a certain garrison location, or for the presence of high value assets. This information would be used to task DISCOVERER II GMTI coverage in the vicinity of the site to confirm or deny such movement, or to task DISCOVERER II SAR coverage to attempt to identify the characteristics of the hostile forces gathered at that location.
The Enhanced Tactical Radar Correlator (ETRAC) was planned by DARPA to support the demo as the ground processing segment, responsible for tasking, receiving the direct down link, processing, and exploiting the data. DARPA planned to cover the costs to include modifications to the ETRAC. The Government desires to leverage the migration path of the CIG/SS infrastructure, which employs the Common Imagery Processor (CIP) and Modular Interoperable Surface Terminal (MIST). The ground interface for the Phase II operational demonstrations will use CIG/SS compliant infrastructure resident in the Tactical Exploitation System (TES), and disseminated using existing infrastructure. It is anticipated the Phase II SI(s) will establish a relationship with the CIP prime contractor, Northrop-Grumman
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