Airborne FLIR Detection of Surface Targets,
NAVAL OCEAN SYSTEMS CENTER SAN DIEGO CA
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An algorithm is presented for predicting the detection ranges of a surface target by an airborne Forward Looking Infrared FLIR system. The total infrared background radiance scene under cloud-free skies is modeled to include the atmospheric path emissions between the target and sensor and the effects of a wind ruffled sea on the surface emissions and sky radiance reflections. A model is also introduced of the average temperature of a ship based upon the solar heating effects throughout a specified course, the ambient meteorological conditions, and the viewing angle. Together, these two models allow the range to be determined where the difference between the apparent ships temperature i.e., the actual ship temperature degraded by the atmospheric transmittance and the effective background temperature of the sea surface as viewed from the sensor altitude is equal to the minimum detectable temperature difference of the FLIR. A case study is presented to demonstrate the vulnerability of a Frigate class ship to detection by an airborne common module FLIR during a five hour period where the ships course changed allowing solar heating of different sides of the ship. The results of this study show considerable increases in predicted detection ranges with altitude using the present algorithm over those based on a fixed temperature difference between a target and its background.
- Infrared Detection and Detectors