Geomagnetic Reference Sensor System (GRSS) for Air Anti-Submarine Warfare (ASW) Navy SBIR FY2008.1 Sol No.: Navy SBIR FY2008.1 Topic No.: N08-009 Topic Title: Geomagnetic Reference Sensor System (GRSS) for Air Anti-Submarine Warfare (ASW) Proposal No.: N081-009-0067 Firm: Arete Associates P.O. Box 2607 Winnetka, California 91396-2607 Contact: John Derderian Phone: (818) 885-2200 Web Site: www.arete.com Abstract: A principal limiter of airborne MAD systems is geomagnetic noise. The long coherence length of geomagnetic noise recommends the use of correlation processing against a reference sensor outside the search area for noise mitigation, and an air-deployed buoy-mounted geomagnetic reference sensor system (GRSS) is a convenient operational configuration. This requires small, light, expendable vector magnetometers with sensitivity comparable to the larger, more expensive intrinsic scalar magnetometers used in airborne MAD detection. Sensitivity will be primarily limited by vertical surface motion noise and rotations of the vector magnetometer. Aret� Associates and Ultra USSI propose to develop an air-deployable GRSS employing a fluxgate vector magnetometer that will meet or exceed the desired sensitivity of 10 pT per root-Hz over the MAD signal band. Surface motion noise will be minimized by isolating the magnetometer from surface wave motion with a mid-water drogue designed to attenuate mid-frequency surface wave motion, and further mitigated by correlation analysis referenced to surface and sub-surface motion sensors. Rotation noise will be mitigated by configuring the vector instrument as a virtual scalar magnetometer (VSM), employing a coordinated combination of motion compensation, advanced processing, and real-time in-sensor calibration compensation. Benefits: The development of a cheap, expendable, air-deployable magnetometer system benefits a number of Navy magnetics efforts in MAD and ELFE detection. The VSM device demonstrated here can be employed in a variety of military applications requiring small, moving platform magnetic systems, particularly on small UAVs. UAV-mounted and ground vehicle-mounted detectors for IEDs and buried land mines benefit. Additionally, with cheap VSM devices, it becomes feasible to field swarms of UAVs for mine or underground facility detection, something that is prohibitively expensive with current intrinsic scalar magnetometers. Commercially, many moving platform magnetometer applications-mineral and petroleum surveys, detection of underground pipelines and buried hazards, etc.-could be done using cheaper VSM devices, or could be mounted on smaller, cheaper UAV platforms. Finally, the small vector magnetometers employed by the VSM are the subject of considerable research and development today and are expected to greatly in sensitivity; VSMs based on these improved vector devices may ultimately outperform the larger, more expensive intrinsic scalar systems. Return