A New Sensor Based Upon a Rotating-Coil Electromagnetic Induction Concept

Abstract

Abstract : The research described in this report was conducted in support of SERDP SEED Broad Agency Announcement (BAA) dated November 7, 2003, Statement of Need UXSEED-05-01, which specifically called for development of new UXO sensors at the proof-of-concept level that will allow development of new or improved discrimination techniques for distinguishing intact ordnance from metallic scrap items. Modern UXO geophysical surveys are normally conducted under GPS control using arrays of magnetometers and/or EMI sensors. Typical vehicular towed arrays produce high density maps of 200,000 2,000,000 data points per acre when using EMI and magnetometer sensor arrays. Target analyses typically involve fitting of perceived magnetic anomalies to dipole signature models. To improve the ability to distinguish intact UXO from metallic scrap, statistical analysis approaches often are applied to the output parameters of the physics-based target-fitting algorithms to improve the classification ability. Although we can approach the 100% detection of UXO threats on fairly uncomplicated ranges, clearing the ranges still requires digging 5-25 non-UXO targets to recover each intact UXO. We have recently concluded that, using currently available magnetic and EMI sensors, little or no further performance gain is likely to be achieved using only the physics-based fitting parameters to make decisions about ordnance classification. Frequency-domain EMI sensors such as the GEM-3(TM) from Geophex Ltd. can operate at frequencies as low as 30 Hz. However, the signal-to-noise ratio of measurements at frequencies below 100 Hz is significantly degraded.