Steward, BJ; Gross, KC; Perram, GP (2012). Characterization and Discrimination of Large Caliber Gun Blast and Flash Signatures. AIRBORNE INTELLIGENCE, SURVEILLANCE, RECONNAISSANCE (ISR) SYSTEMS AND APPLICATIONS IX, 8360, 836006.
Two hundred and one firings of three 152 mm howitzer munitions were observed to characterize firing signatures of a large caliber gun. Muzzle blast expansion was observed with high-speed (1600 Hz) optical imagery. The trajectory of the blast front was well approximated by a modified point-blast model described by constant rate of energy deposition. Visible and near-infrared (450 - 850 nm) spectra of secondary combustion were acquired at similar to 0.75 nm spectral resolution and depict strong contaminant emissions including Li, Na, K, Cu, and Ca. The O-2 (X -> b) absorption band is evident in the blue wing of the potassium D lines and was used for monocular passive ranging accurate to within 4 - 9%. Time-resolved midwave infrared (1800 - 6000 cm(-1)) spectra were collected at 100 Hz and 32 cm(-1) resolution. A low dimensional radiative transfer model was used to characterize plume emissions in terms of area, temperature, soot emissivity, and species concentrations. Combustion emissions have similar to 100 ms duration, 1200 - 1600 K temperature, and are dominated by H2O and CO2. Non-combusting plume emissions last similar to 20 ms, are 850 - 1050 K, and show significant continuum (emissivity similar to 0.36) and CO structure. Munitions were discriminated with 92 - 96% classification accuracy using only 1 - 3 firing signature features.