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Figure 22. Ringdown for different TEMTADS receiver coilsFigure 23. Observed TEMTADS background variation at several sites.At early times the signal due to a target’s EMI response is decaying algebraically with a powerlaw somewhere between -1/2 and -3/2, more slowly than the noise. At late times the decay variesfrom t -3/2 to exponential, more rapidly than the noise. Thus it is likely that for at least sometargets the signal will be obscured by noise at early and/or late times. Figure 24 shows signal andnoise histograms for targets and background shots at 0.1, 1.0 and 10 ms. The data were collectedwith the man-portable TEMTADS at the 2011 Camp Beale classification demonstration. Thedistributions are fairly well separated at 0.1 ms, overlap a bit more at 1 ms and overlapconsiderably at 10 ms. Clearly the late time response data can be significantly corrupted bynoise. The question is how important this effect is for classification performance.29
Figure 24. Signal and noise histograms at 0.1, 1.0 and 10 ms for the man-portableTEMTADS at Camp Beale.We used the signature library to address this question. We used the standard library matchingclassification procedure [13, §6.4] on polarizabilities calculated from all of the former Camp SanLuis Obispo munitions and clutter signatures (Table 3 and Table 4), varying the decay timerange. These data were collected in air with the targets in on a test stand below the TEMTADSarray, with target/sensor separations chosen to give good strong signals. We should be seeing theeffects of decay time range on how similar the munitions and clutter signatures appear ratherthan the effect of noise on the comparison. Figure 25 shows the results in the form of ReceiverOperating Characteristic (ROC) curves. The ROC curve traces performance in terms ofmunitions items correctly classified vs clutter items as a classification threshold is varied. Thestandard decay range is 0.04-25 ms. The plot on the left shows how performance varies as thelower limit is increased from 0.04 ms to 2 ms. The plot on the right shows how performancevaries as the upper limit is decreased from 25 ms to 1 ms. At the low end performance degradeswith >0.1 ms early time cutoff, while at the high end performance degrades with
Page 1 and 2: FINAL REPORTMagnetic Surface Modes
Page 3 and 4: AbstractThis research project conce
Page 5 and 6: List of TablesTable 1. MR-1595 targ
Page 7 and 8: List of AcronymsBUDDARPAEMIESTCPGEM
Page 9 and 10: AcknowledgementsThis project was a
Page 11 and 12: BackgroundIntroductionOver the past
Page 14 and 15: (11)V(t) = −μ 0 n R n T C R (r 0
Page 16 and 17: in blue. Finely spaced gray lines a
Page 18 and 19: Figure 5. Comparison of quadrature
Page 20 and 21: Although useful, these EMI signatur
Page 22 and 23: Materials and MethodsData Collectio
Page 24 and 25: Figure 9. (a) EMI response curves m
Page 26 and 27: have used the site for testing and
Page 28 and 29: ProjectilesMunition Type Variants M
Page 30 and 31: Figure 14. Principal axis polarizab
Page 32 and 33: transfer coefficient h according to
Page 34 and 35: around ½ depending on the object [
Page 36 and 37: We have considered the utility of u
Page 40 and 41: Figure 25. Classification performan
Page 42 and 43: Conclusions and Implications for Fu
Page 44: 13. James B. Kingdon, Bruce J. Barr

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