Expendable Trihedral Corner Reflectors for Target Enhancement and Position Control in RADARSAT-1 Fine Beam Mode SAR Imagery: Results from an Exercise Narwhal Pre-Trial Deployment.

摘要

In August 2004 Defence Research and Development Canada (DRDC) Ottawa will participate in Exercise Narwhal, which will be held on Baffin Island. The objectives of Exercise Narwhal are to exercise the Canadian Forces? (CF) role in supporting the Nunavut territorial government's response to a crisis within the Canadian Forces Northern Area (CFNA), to exercise Headquarters CFNA, and to exercise Canadian sovereignty by projecting a CF presence within the North. One activity within Exercise Narwhal is simulation of the recovery of a crashed rocket and satellite payload. For this activity, expendable trihedral Corner Reflectors (CRs) will be distributed over an area of approximately 3200 km2 to increase the radar reflectivity of the crash site. In preparation, DRDC Ottawa conducted a mini trial in May 2004. The objective of the mini trial was to validate the methodology of determining the pointing angles of the trihedral CRs, to assess the visibility of trihedral CRs of different sizes in RADARSAT-1 fine beam mode imagery, and to obtain a coincident Synthetic Aperture Radar (SAR) dataset with Ground Control Points (GCPs). Trihedral CRs of various sizes were deployed at Connaught Range and other trihedral CRs were deployed throughout the National Capital Region (NCR); three fine beam mode RADARSAT-1 passes were acquired. All deployed CRs were visible with the exception of the smallest, which had a 30 cm back spine dimension, thus validating the deployment methodology. The visibility of trihedral CRs depends upon the normalized RCS of the background against which they are deployed. The smallest CR visible had a back spine dimension of 45 cm. A problem with the RADARSAT-1 orbit resulted in only two of the three images containing all of the GCPs; however, two coincident SAR images with GCPs were produced and are available for SAR geometry studies. Prior to this exercise SAR imagery with ground control was not readily available.