<title>Foliage penetration data collections and investigations utilizing the P-3 UWB SAR</title>

Abstract

To quantif' the ability of a synthetic aperture radar (SAR) system using an automatic target recognition (ATR) system to detect targets obscured by foliage, an ultra-wideband, UHF-band, polarimetric SAR was constructed by ERIM under ARPA funding and installed on a Navy P-3 aircraft controlled by the Naval Air Warfare Center (NAWC). The system was implemented as an upgrade to the existing X-, L-, and C-band SAR system already on this aircraft. A series of experiments funded by ARPA and Wright Laboratory were undertaken in 1995 to investigate foliage penetration (FOPEN).In this paper, the data and ground truth collected and their utility for investigations ofFOPEN phenomenology and AiR algorithms will be presented. These data are being placed into a database for distribution to AiR algorithm developers.The characteristics ofthe P-3 UWB SAR will be discussed. The image formation technique used (which is based on the omega-k technique for wide-band, wide-integration-angle data) will be presented, along with the RFI suppression techniques used. Ofparticular interest will be the technique used for the required motion compensation. Results from recent investigations using the P-3 UWB SAR data will be discussed.

<title>Distortion-invariant filters for foliage-penetration (FOPEN) synthetic aperture radar</title>

“…We combined these to produce Polarimetric Whitening Filter (PWF) imagery using whitening filter concepts detailed earlier [6,7,8,9]. The whitening process combines the three complex-valued channels into a single real-valued image by the formula x=yt(E_l)*y (1) where y ={hh hv vv]T j the vector containing the elements from the three complex-valued channels, and E is the 3x3 Hermitian covariance matrix of the clutter data. No zero cross-correlation assumptions were made.…”

“…The processing of such data to produce imagery is detailed elsewhere [1]. Prior work on object detection in FOPEN data has used contrast box methods [2], split aperture techniques [3J, use of polarization information [4,5], and other techniques.…”

“…One flight collected target signature data from targets deployed in the open, while the other flights were devoted to collecting data with the vehicles hidden in the trees and along tree lines. The SAR used was the ERIM/NAWC UWB (215 MHz-724 MHz) P-3 SAR, a fully-polarimetric sensor flown on a Navy P-3 aircraft [1]. The data was collected in three polarizations (1111, HV, VV).…”

<title>Parallel processing technology for large-scale production of synthetic aperature radar imagery</title>

“…Over the past few years, the Ultra-Wideband (UWB) P-3 sensor [2] has been used to collect data on stationary vehicles under foliage and camouflage over a variety of backgrounds [4,5]. MITLincoln Laboratory was in charge of conducting the data collections, and was responsible for generating wellfocused radiometrically and polarimetrically calibrated SAR imagery from the UWB P-3 data.…”

Demonstration of reduced false alarm rates using simulated L-band polarimetric SAR imagery of concealed targets

“…X-band). Deep penetration into foliage can only be achieved at lower frequencies, for example at VHF or UHF [1][2][3][4]. The move to lower frequencies has a number of important consequences for SAR operation: lower frequency means that longer apertures are required to maintain resolution.…”