Aerosol Discrimination by Electronic High- and Low-Pass Filtering

Abstract : Two electronic techniques are investigated for discriminating between aerosol and rigid-target (such as aircraft and terrain) return signals in pulsed active optical sensors (proximity fuzes). Short transmitter pulses approximately 5 to 10 ns full width at half maximum are considered in systems with pencil-beam influence patterns. Relative pulse stretching of aerosol returns is exploited for discrimination by using either a differentiating circuit or a low-pass filter to bring out pulse-speed or pulse-width differences. The investigations involve modeling and analysis, as well as testing the discrimination schemes with measured aerosol-return signals from cumulus clouds. Both techniques are found to be potentially effective for designing proximity fuzes that reject aerosol signals. (Author)