Recovery of badly motion-degraded SAR imagery by the use of frequency-randomized waveforms
Keith Morrison - Cranfield University
Tue, 27 April 2004, 1:30 PM - 3:20 PM
The use of SAR imaging is an important tool in the laboratory RCS characterization of signature critical platforms. Despite measures to the contrary, air turbulence and mechanical vibration can produce complex perturbations of the target during the imaging process. Model code was written to provide simulations over a wide range of representative target motions and imaging schemes. The slow swept-frequency data collection schemes of many laboratory radars means that the target can undergo significant motion during and between pulses, leading to substantial and time-varying defocusing of range profiles. Conventional motion-correction schemes cannot be used as they rely on the presence of clearly defined range profiles over the imaging process. It was found that replacement of a monotonically increasing waveform with one in which the frequency sampling order was repeatedly randomized could produce a significant recovery of the range profiles. In combination with data averaging, this can provide a significant recovery of the imagery. The pattern of the image degradation was found to have a complex dependence on the radar waveform scheme and target motion characteristics.
Dr Keith Morrison - Cranfield University
Keith Morrison received the B.Sc. in physics with astrophysics from the University of Leicester, Leicester, U.K. in 1983, and the Ph.D. in astronomy and astrophysics from the University of St.Andrews, St.Andrews, U.K. in 1987.
From 1987-1994 he was with the British Antarctic Survey, Cambridge, carrying out research in space plasma physics. Between 1994 and 2000 he was at the University of Sheffield, which included a three-year role as programme manager of the GB-SAR project. From 2000 to 2002 he was with the UK?s Defence and Evaluation Research Agency at Malvern, involved in the RCS measurement of radar stealthy platforms. Since 2002 he has been a senior lecturer at Cranfield University within the Royal Military College of Science. Research interests include the development, application and modelling of ground-based synthetic aperture radar techniques applied to environmental remote sensing. Of particular interest is the problem of imaging wind-blown vegetation, and 3-D SAR tomography.
In 1998 he was awarded NASA?s Group Achievement Award, and in 2002 the Taylor and Francis and Remote Sensing and Photogrammetry Society?s Best Letter Award for the publication ?Three-dimensional X-band SAR Imaging of a small conifer tree?.