The Value Of Multi-Component Tem Data For The Estimation Of Uxo Target Parameters

Two multi-component multi-gate data sets from the Naval Research Laboratory’s Baseline<br>Ordnance Classification Test Site at Blossom Point, one acquired statically with a Geonics EM61-3D-<br>3C and the other acquired dynamically with a Zonge NanoTEM system (DNT), are analyzed to<br>determine the relative classification performance of the two systems. Not surprisingly, our classification<br>performance is better with 3-component static data than it is with the 3-component dynamic data.<br>Confirming published work by Grimm [4], classification is significantly improved when it is applied to<br>the 3-component static data than when it is applied to a decimated data set consisting of only a single (z)<br>component. However, early analyses of the dynamic data indicated that horizontal components provide<br>marginal, if any, improvements in classification. Noise analyses of data from the two systems show that<br>noise levels in the EM61-3D data set are approximately 40dB lower than those in the DNT system and<br>that noise levels in the horizontal components at late times are 2-5 times higher in the vertical<br>component. Noise reduction in statically acquired data can be attributed to stacking (~20dB) and the<br>elimination of microphonic noise from antenna cart movements. With dynamically acquired data, the<br>higher noise levels in the horizontal components together with uncertainties in antenna position and<br>attitude are most likely the reason that the horizontal components do not unequivocally improve<br>classification performance in the dynamic data.