COAT/Target-Signature Interactions
Abstract
Target speckle modulation effects have been investigated experimentally using a number of scaled realistic targets with different shapes and surface textures, and analytically using theoretical target signature models (some generated by General Research Corporation (GRC)) in a computer simulation model of a multidither COAT system. The experimental results have shown that maximum contrast ratios of 0.79 can occasionally be obtained, but that the average is much lower. Significant receiver aperture integration effects cause reduction of the contrast ratio. Temporal frequency spectra obtained by rotation of the targets agree with spatial frequency data obtained by fast Fourier transform processing of the target signature data. Preliminary computer simulation results using high contrast ratio speckle data from GRC show degraded COAT system performance. The severity of the degradation has been attributed in part to: (1) unrealistically harsh assumptions in the GRC speckle model including assumption of a point receiver, and an inadequate sampling of the speckle waveform; (2) several discrepancies between the real COAT system and the computer simulation model, especially in the automatic gain control portion of the system. A preliminary adjustment of the COAT simulation model has led to reduced susceptibility to high contrast speckle modulation. In addition, theoretical arguments, corroborated by our experimental results, indicate that such high contrast ratios are not realistic at visible wavelengths.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1975
- Accession Number
- ADA345012
Entities
People
- J. E. Pearson
- M. E. Pedinoff
- S. A. Kokorowski
Organizations
- HRL Laboratories