The ultraviolet (UV) band of the electromagnetic spectrum has the potential to be used as the host medium for the operation of guided weapons. Unlike in the infrared (IR) band, a target propelled by an air-breathing jet engine produces no detectable radiation in the UV band and is opaque to the background UV produced by the sun. Successful engineering of spectral airborne IR countermeasures (CMs) against existing two-color IR seekers has encouraged missile counter-countermeasure designers to utilize the silhouette signature of an aircraft in the UV as a means of distinguishing between a true target and a flare CM. We describe the modeling process of a dual-band IR and UV rosette scan seeker using CounterSim, a missile engagement, and countermeasure simulation software package developed by Chemring Countermeasures Ltd. Results are shown from various simulated engagements of the dual-band man-portable air defence (MANPAD) system with a C-130 Hercules. These results have been used to estimate the aircraft’s baseline vulnerability to this MANPAD threat and to develop a model flare countermeasure that is successful in greatly improving the survivability of the aircraft.
The Ultraviolet (UV) band of the electromagnetic (EM) spectrum has the potential to be used as the host medium for the
operation of guided weapons. Unlike in the Infrared (IR), a target propelled by an air breathing jet engine produces no
detectable radiation in the UV band, and is opaque to the background UV produced by the Sun.
Successful engineering of spectral airborne IR countermeasures (CM) against existing two colour IR seekers has
encouraged missile counter-countermeasure (CCM) designers to utilise the silhouette signature of an aircraft in the UV
as a means of distinguishing between a true target and a flare CM. In this paper we describe the modelling process of a
dual band IR and UV rosette scan seeker using CounterSim, a missile engagement and countermeasure simulation
software package developed by Chemring Countermeasures Ltd. Results are shown from various simulated engagements
of the dual band MANPAD with a C-130 Hercules modelled by Chemring Countermeasures. These results have been
used to estimate the aircrafts’ vulnerability to this MANPAD threat. A discussion on possible future optical
countermeasures against dual band IR-UV seekers is given in conclusion to the simulation results.
The ability to accurately model background radiation from the sun is important in understanding the operation of missile
systems with ultraviolet (UV) guard channels. In theory a missile system’s UV channel detects a target’s silhouette,
caused by its ‘negative contrast’ with respect to background UV radiation. The variation in background levels of UV will
therefore have an effect on the operability of a missile system that utilises a UV channel.
In this paper an update on the measurement and comparison of background UV-A radiation to data produced by
Moderate Resolution Atmospheric Transmission 5 (MODTRAN®5) is given. In the past surface flux and radiance data
calculated using MODTRAN®5 has been compared to data from the World Ozone and Ultraviolet Data Centre
(WOUDC) archive, and measurements taken by the author at the Defence Academy of the UK. With the aid of spectral
measurement equipment, new measurements have been made and compared with the radiance profiles produced by
MODTRAN®5, including measurements made throughout both winter and summer months. Also discussed are the
effects of scattering and absorption by different cloud types on the amount of radiation observed at the Earth’s surface.
The ultraviolet (UV) band of the electromagnetic spectrum has potential as a host medium for the operation of guided weapons. Unlike in the infrared (IR), a target which is propelled by an air breathing jet engine generates no detectable radiation in the UV band, and is opaque to the background UV produced by the Sun. In theory the blocking of UV radiation from the sun causes a detectable ‘negative contrast’ between the target and the background. In order to determine the outcome of engagement scenarios between airborne platforms and guided weapon systems that utilise a guard channel operating in the UV, it is necessary to accurately model background UV levels. This paper presents a comparison between the atmospheric modelling code moderate resolution atmospheric transmission (MODTRAN®5) and measured data. The spectral irradiance levels generated by the MODTRAN®5 code are compared to those of the World Ozone and Ultraviolet Data Centre (WOUDC ) database, for various global positions and times of year. Radiance data collected at the Defence Academy of the United Kingdom (Shrivenham, England) for various observer geometries is also compared to that generated by the MODTRAN®5 code.
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