Based on the success of the 5x5 time-domain electromagnetic MTADS (TEMTADS) under ESTCP project MR-200601, the Naval Research Laboratory (NRL) undertook efforts to transition this technology to smaller, man-portable (MP) and hand-held (HH) systems for deployment in more confined terrains.  The MP system was constructed as a 2x2 array of the sensors developed for the original TEMTADS.  For the HH sensor, a single, coaxial transmitter (Tx)/receiver (Rx) coil pair was developed to capture the performance of the original sensor while made rugged enough for handheld use in the field.  The required data diversity for the HH sensor comes from making a series of measurements over the target using a physical template for precise relative geolocation.  Both systems are designed to be deployable in increasingly inaccessible areas where vehicle-towed sensor arrays cannot be used.

The objective of these demonstrations was to validate the performance of the two TEMTADS adjunct platforms through blind testing at prepared and live sites.  The systems were evaluated in terms of both classification performance (e.g., false alarm rejection) and appropriateness for fielding (i.e., production rate, usability, etc.).

Demonstration Results

Demonstrations of these systems have been conducted at the test facility at Blossom Point, MD; at the unexploded ordnance (UXO) Standardized Test Site at Aberdeen Proving Ground (APG), MD; and at live sites in Bridgeport, CT and Washington, DC.  These sites offer a range of UXO sizes and types along with a selection of munitions-related scrap and cultural clutter.  The results of these demonstrations are discussed in terms of classification performance and production rate.

For the MP system, the APG results indicated that the inversion performance of the system was not comparable to that of the full TEMTADS 5x5 array for lower signal-to-noise ratio (SNR) targets due to the limits of the smaller data set (fewer looks at the target).  The results of the live site demonstrations supported the conclusions drawn after the APG demonstration. 

Revision of the sensor technology was indicated for the MP system to collect sufficient data over an anomaly.  A modified version of the TEMTADS electromagnetic induction (EMI) sensor was designed and built, replacing the single, vertical-axes receiver loops of the original coils with three-axis receiver cubes.  The new sensor elements were designed to have the same form factor as the originals, aiding in system integration.

The HH sensor was designed for use in extremely limiting terrain and for integration with unique positioning technologies.  The APG results for the HH sensor indicated that the inversion performance of the system using a 36-point observation grid was comparable to that of the full TEMTADS 5x5 array.

Implementation Issues

The goal of these projects was to design and field units more amenable to operation in more confined terrain and topography.  This was to be accomplished by implementing MP and HH configurations with the same UXO classification performance as the larger, vehicle-towed NRL TEMTADS.  The MP configurations could also be adapted for vehicle-towed configurations using smaller, simpler tow vehicles.  A second goal was to transition these technologies from being research prototypes to use in the industrial community where appropriate.  The mechanics of collecting classification-grade EMI data with these systems have been shown to be fairly routine in the research community.  As part of the ESTCP Munitions Response Live Site Demonstrations, industrial partners will be exposed to the MP system and the associated data collection and processing procedures.  The success of this effort will be evaluated as an ongoing part of the Live Site Demonstrations.  Analysis of data from these systems remains somewhat of a specialty, requiring specific software and knowledge to proficiently conduct.  The successful transition of the TEMTADS 5x5 array data quality control/analysis process to the Geosoft Oasis montaj environment provides a clear pathway for resolving these issues.  A final implementation issue is that a clear path to making the TEMTADS adjuncts commercially available has not been identified yet.  Discussions with various groups along these lines are ongoing.