Potential terrorists/adversaries can exploit a wide range of airborne threats against civilian and military targets. Currently there is no effective, low-cost solution to robustly and reliably detect and identify low observable airborne vehicles such as small, low-flying aircraft or cruise missiles that might be carrying chemical, biological or even nuclear weapons in realistic environments. This paper describes the development of a forward-based fence that contains a multi-modal mix of various low cost, low power, netted sensors including unsophisticated radar, acoustic and optical (Infrared and visible) cameras to detect, track and discriminate such threats. Candidate target (Cessna, Beech Craft, crop duster, and cruise missile) signature phenomenologies are studied in detail through either theoretical, numerical simulation or field experiment. Assessments for all three modalities (Radar, acoustic and IR) indicate reasonable detectability and detection range. A multi-modal kinematic tracker is employed to predict the location, the speed and the heading of the target. Results from a notional, template based classification approach reveal reasonable discrimination between different aircraft tested in the field experiments.
A user friendly modular computer code is described for CW coherent laser radar which includes all relevant physical effects needed to evaluate the probability of detection versus time after launch for ballistic missiles or other targets of interest. The beginning point of the code is the conventional laser radar range equation. Atmospheric attenuation is determined from an integral FASCODE calculation, and the laser radar range equation is solved for a curved-earth geometry including free air turbulence induced beam spreading. Several different atmospheric turbulence models are selectable. Target cross-sections can be input into the code as a function of aspect angle Coherence time and transverse coherence length limits are included in the code. Beam jitter effects are also calculated. The carrier-to-noise ratio is calculated including all of these (complicated) variables and degradations. The code then calculates the probability of detection of the target as a function of time using incoherent integration of coherent sub-pulses. The governing equations and practical results are presented for detection and tracking of long range theater ballistic missiles from airborne surveillance platforms. The use of CW lasers requires increased measurement times compared to pulsed lasers and results in an averaging of the target fading statistics.
Range information from a laser radar can be used to rapidly converge target track files for theater missile defense from an airborne sensor platform. This paper examines the application of laser radar technology to this mission. Eyesafe lasers including carbon dioxide, holmium/thulium, and YAG shifted by optical parametric oscillators or Raman cells are considered. Performance analyses include the effects of wavelength dependent target cross sections, atmospheric attenuation and background radiation, and either direct or heterodyne detection processes on the received signal to noise ratio. Signal processing analyses include the effects of noise statistics, target fading for either direct or heterodyne detection, and the optical wavelength dependent effects of atmospheric turbulence on system false alarm and detection probabilities.
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