<title>Multiple-resolution study of Ka-band HRR polarimetric signature data</title>

Abstract

SAR resolution and polarization performance studies for ATR algorithms have been the source of recent attention. Thorough investigations are often hindered by the lack of rigorously consistent high-resolution full-polarimetric signature data for a sufficient number of targets across requisite viewing angles, articulations and environmental conditions. While some evaluative performance studies of high-value structures and conceptual radar systems may be effectively studied with limited field radar data, to minimize signature acquisition costs, pose-independent studies of ATR algorithms are best served by signature libraries fashioned to encompass the complexity of the collection scenario 1 .In response to the above requirements, the U.S. Army's National Ground Intelligence Center and Targets Management Office originated, sponsored, and directed a signature project plan to acquire multiple target signature data at Eglin, AFB using a high resolution full-polarimetric Ka-band radar 2 . TMO and NGIC have sponsored researchers at both the Submillimeter-Wave Technology Laboratory and SimulationTechnologies to analyze the trade-off between signature resolution and polarimetric features (ongoing research) of this turntable data. The signature data was acquired at five elevations spanning 5° to 60° for a T-72M1, T-72B, M1, M60-A3 and one classified vehicle. Using signal processing software established in an NGIC/STL-based signature study 3 , researchers executed an HRR and ISAR cross-correlation study involving multiple resolutions to evaluate peak performance levels and to effectively understand signature requirements through the variability of multiple target RCS characteristics.The signature-to-signature variability quantified on the four unclassified MBTs is presented in this report, along with a description and examples of the signature analysis techniques exploited. This signature data is available from NGIC/TMO on request for Government Agencies and Government Contractors with an established need-to-know.

A Study of Target Variability and Exact Signature Reproduction Requirements for Ka-Band Radar Data

“…Initially, the arithmetic mean and median of the azimuth averaged RCS turntable data were calculated for each signature measured using ERADS' compact range (CR) radar as shown in Tables To evaluate the impact of these differences on the signature-to-signature RCS variability of high-resolution field and scale-model imagery, an averaged percent difference (APD) algorithm, developed and detailed by STL researchers in prior signature investigations 5 was executed. The APD algorithm was implemented on the high resolution ISAR imagery at 1°a spect increments for the entire spin of the target (360 images) and angular adjustments were performed to minimize the APD, thus eliminating azimuth misalignment between signature sets.…”

A comparison of fully polarimetric x-band ISAR imagery of scaled model tactical targets

“…1 Therefore, only a brief description will be given here. The ISAR images that result from the threshold method described in Step 2 are overlapped with each other using the location of the maximum correlation amplitude calculated in Step 4.…”

“…Several test data collections were then performed on the 1/35 th scale model T72 in several different operational configurations, and in a complex two-target scene wherein it was mounted to the back of a much larger vehicle. A comparison of the ISAR images was performed similar to the correlation studies done in previous works 1,2,3 where ISAR images are correlated against each other to determine the quality of the match. It will be shown that the T72 data sets correlate very well even across different radar platforms.…”

A Study of the X-Band Radar Signature Characteristics for Main Battle Tanks in Operational Environments

“…The comparative methodology used to quantify the signature-to-signature conditions and environments RCS variability was originally developed by STL researchers for evaluating (and establishing similitude between) MMW and scaled submillimeter-wave radar measurements (5) . To quantify the impact of these differences, independently measured images were cross-correlated using an averaged percent difference (APD) algorithm (7) .…”

“…(1,3,5,7) The program has concentrated on analyzing radar signatures from multiple main battle tanks (MBTs) in order to quantify the differences in Ka-band signatures of vehicles due to intraclass and interclass target variations. The metrics and model building procedures now provide the foundation for executing an analysis of target structures in operational environments.…”