Detection of land-mines using ultra-wideband radar data and time-frequency signal analysis

The authors present a study of the backscattered signatures from various types of land-mines placed either on the Earth´s surface or buried underground, and their time-frequency (t-ν) distributions. A BoomSAR designed by the Army Research Laboratory (ARL) transmits ultra-wideband (UWB) signals to a test area to be inspected. The backscattered signals are used to form synthetic aperture radar (SAR) imagery and also the corresponding time-frequency distributions. The t-ν plots are generated of the distributions of several mines and ´confusers´ (i.e. undesirable debris that are similar to mines in terms of amplitude and shape). For both metal and plastic mines, SAR images are generated and the t-ν distributions are obtained using the backscattered signals generated by an electromagnetic (EM) numerical model and are compared against the measured data. Time-frequency characteristics of mines and confusers that may be useful for demining purposes are investigated. Although measurements and EM predictions show good agreement in most cases, the main purpose of the work is to obtain the characteristics of the t-ν distributions of the actual (dielectric and conducting) mines used, as well as those of the ´confusers´ so that they can be distinguished from the true mines. This has been achieved in all cases shown, and many distinctive features of each have been identified. These could later be used for the development of automated algorithms for in-situ mine detection and could be combined with alternative approaches that have also shown promise for classification purposes, as planned for future research.