Abstract: A Doppler radar system includes a Doppler radar processor, a memory in communication with radar processor and a transmit/receive controller. The memory includes computer readable instructions that cause the Doppler radar processor to transmit a radar signal toward the airborne object at a frequency; receive reflected radar signals off of the airborne object, including frequencies produced as a result of Doppler effect due to relative motion between features of the airborne object and the radar system; and Fourier transform the received signals into the frequency domain. Peak frequencies and their harmonic frequency families are sorted and identified. The logarithm of the Fourier transform is calculated to generate a quefrency cepstrum. To identify features producing cyclic, periodic Doppler frequency patterns, peak quefrencies and rahmonic families associated with a quefrency peak are sorted and identified. The rotational state of the airborne object based on the identified quefrency families is determined.

Abstract: A Doppler radar system includes a Doppler radar processor, a memory in communication with radar processor and a transmit/receive controller. The memory includes computer readable instructions that cause the Doppler radar processor to transmit a radar signal toward the airborne object at a frequency; receive reflected radar signals off of the airborne object, including frequencies produced as a result of Doppler effect due to relative motion between features of the airborne object and the radar system; and Fourier transform the received signals into the frequency domain. Peak frequencies and their harmonic frequency families are sorted and identified. The logarithm of the Fourier transform is calculated to generate a quefrency cepstrum. To identify features producing cyclic, periodic Doppler frequency patterns, peak quefrencies and rahmonic families associated with a quefrency peak are sorted and identified. The rotational state of the airborne object based on the identified quefrency families is determined.

Abstract: A Doppler radar system includes a Doppler radar processor, a memory in communication with radar processor and a transmit/receive controller. The memory includes computer readable instructions that cause the Doppler radar processor to transmit a radar signal toward the airborne object at a frequency; receive reflected radar signals off of the airborne object, including frequencies produced as a result of Doppler effect due to relative motion between features of the airborne object and the radar system; and Fourier transform the received signals into the frequency domain. Peak frequencies and their harmonic frequency families are sorted and identified. The logarithm of the Fourier transform is calculated to generate a quefrency cepstrum. To identify features producing cyclic, periodic Doppler frequency patterns, peak quefrencies and rahmonic families associated with a quefrency peak are sorted and identified. The rotational state of the airborne object based on the identified quefrency families is determined.

Abstract: A method for constructing a solar heat collector comprises applying a bit array to a sheet of reflective material to create a sheet of solar reflectors, each bit in the bit array creating a solar reflector having a known focal point; and mating the sheet of solar reflectors to a heat absorbing layer such that at least a portion of the heat absorbing layer passes through a focal point of at least some of the solar reflectors.

Abstract: A simple and portable solar heat collector has a sheet of solar reflectors, each of the solar reflectors having a focal point, and tubing for routing heat absorbing fluid through the focal point of at least some of the solar reflectors. The tubing has an input tube for receiving heat absorbing fluid and an output tube for outputting heated heat absorbing fluid. The sheet of solar reflectors may have a sun-facing side and a non-sun-facing side. A first part of the tubing is adjacent to the non-sun-facing side of the sheet of solar reflectors, and a second part of the tubing extends from the first part of the tubing through holes in the sheet of solar reflectors to the focal point of at least some of the solar reflectors.

Abstract: A Doppler radar system includes a Doppler radar processor, a memory in communication with radar processor and a transmit/receive controller. The memory includes computer readable instructions that cause the Doppler radar processor to transmit a radar signal toward the airborne object at a frequency; receive reflected radar signals off of the airborne object, including frequencies produced as a result of Doppler effect due to relative motion between features of the airborne object and the radar system; and Fourier transform the received signals into the frequency domain. Peak frequencies and their harmonic frequency families are sorted and identified. The logarithm of the Fourier transform is calculated to generate a quefrency cepstrum. To identify features producing cyclic, periodic Doppler frequency patterns, peak quefrencies and rahmonic families associated with a quefrency peak are sorted and identified. The rotational state of the airborne object based on the identified quefrency families is determined.

Abstract: A method for classifying an airborne object detected by a radar system is disclosed. The method includes the steps of identifying quefrency peaks in a quefrency cepstrum generated from a received radar return signal, the quefrency peaks indicative of a rotating physical feature of the airborne object. A rotational velocity of the physical feature is determined based on the quefrency peaks. The method further includes determining at least one parameter or characteristic of a physical feature of the airborne object. The at least one characteristic is compared to a known physical feature stored in a classifier database, wherein a classification decision is made upon identifying a match between the at least one characteristic and a known physical feature stored in the database.

Abstract: An active state estimation system comprises radar systems for obtaining sensor measurements, data storage devices for storing the sensor measurements, and computer processors in communication with the data storage devices. A memory stores program instructions which cause the computer processors to initialize a system having state variables and also having unknown, multidimensional, arbitrarily time-varying parameters, but which are subject to known bounded values. Sensor measurements for the object being tracked are then received, and applied to an estimating filter that explicitly uses a mean square optimization criterion that separately accounts for measurement errors and said bounding values, to produce estimates of the true state of the system. The system also determines whether a regime change has occurred based on the estimates of the true state of the system, and if so, determines updated known bounded values that are used to update the boundaries used by the system.

Abstract: A system for testing the covariance fidelity of an optimal reduced state estimator comprises data storage devices for storing testing data, computer processors in communication with the data storage devices, and a memory storing program instructions for execution by the computer processors. Execution of the program instructions may cause the computer processors to provide an optimal reduced state estimator having state variables and unknown, multidimensional, arbitrarily time-varying parameters, subject to known bounded values. A random component and a bias component of the optimal reduced state estimator may be identified, and then separate evaluations of the components may be performed to determine a fidelity of the optimal reduced state estimator. The random component may be evaluated at a selected epoch and a Mahalanobis Distance Value determined for the random component. The bias component may be evaluated at the selected epoch and a probability of containment determined at a selected MDV.

Abstract: A computerized classifier system that forms convex hulls containing all training experiences for each target class (e.g. threat/non-threat) is disclosed. The intersection of convex hulls for each pair of classes defines a region of ambiguity in feature space. Measurement of feature vector(s) outside an ambiguous region of feature space leads to a class decision while measurement of feature vector(s) within an ambiguous region of feature space defined by convex hulls causes a transition to a new feature space with new features. In particular embodiments, measured feature data includes estimated motion states and electrical lengths of a given object, and range, velocity and acceleration image data from second phase differences for debris mitigation.

Abstract: A method and system is disclosed for tracking object clusters that reduces the complexity of isotropic scaling and conformal transformations that are used with current methods of tracking clusters. The method and system comprise obtaining a first sensor image and a second sensor image. Then, angular measurements between objects of the first sensor image are determined. Next, the second sensor image is rotated to align it with the first sensor image, and then angular measurements between objects of the second sensor image are determined. Then angular measurements from the first sensor image are compared to angular measurements of the second image, and correlated object clusters are identified.

Abstract: A method for suppressing clutter when detecting objects of interest in a radar system is provided. The method includes defining a plurality of scatterer classes corresponding to a plurality of predetermined scatterer motion types, at least one of the classes corresponding to ballistic acceleration, and at least one of the classes corresponding to non-ballistic acceleration. A plurality of sensor pulses are transmitted, and reflected return pulses are received. Scatterers identified in the radar return signal are associated with one of the scatterer classes. A set of complex weights is generated and applied to the radar return signal data to null scatterers associated with the class corresponding to ballistic acceleration.

Abstract: A computerized classifier system that forms convex hulls containing all training experiences for each target class (e.g. threat/non-threat) is disclosed. The intersection of convex hulls for each pair of classes defines a region of ambiguity in feature space. Measurement of feature vector(s) outside an ambiguous region of feature space leads to a class decision while measurement of feature vector(s) within an ambiguous region of feature space defined by convex hulls causes a transition to a new feature space with new features. In particular embodiments, measured feature data includes estimated motion states and electrical lengths of a given object, and range, velocity and acceleration image data from second phase differences for debris mitigation.

Abstract: An apparatus for capture of an unmanned aerial vehicle (UAV) comprises a wind tunnel including at least one fan for generating airflow in the wind tunnel; sensors for sensing characteristics of the UAV; and a control system coupled to said sensors and said at least one fan. The control system is configured to cause the at least one fan to generate airflow based on the sensed characteristics of the UAV to bring the UAV that is in the wind tunnel to a low or zero airspeed above a floor of the wind tunnel, thereby allowing the UAV to be dropped onto the floor of the wind tunnel when the airflow and a motive force of the UAV are stopped.

Abstract: A simple and portable solar heat collector comprises a sheet of lenses, the sheet of lenses receiving light on a first side and focusing the light at focal points on a second side; and tubing on the second side. The tubing comprises an input tube for receiving heat absorbing fluid, internal tubing for routing heat absorbing fluid through at least some of the focal points of the sheet of lenses, and an output tube for outputting heated heat absorbing fluid.

Abstract: An acoustic system is disclosed to help conceal the location of a shooter. The system comprises one or more acoustic decoys and an activating module for sending one or more triggering signals from a weapon to the acoustic decoys. The acoustic decoy comprises a processor, a sound generating module capable of producing a weapon discharge sound, and a receiver connected to an antenna. The decoy processor causes the sound generating module to produce a weapon discharge sound when the receiver receives a triggering signal through the antenna. The activation module comprises an activation processor, an imminent discharge sensor for sensing motion indicative of an imminent weapon discharge, a signal generator, and a transmitter. The activation processor causes the signal generator to generate a triggering signal when the imminent discharge sensor senses an imminent weapon discharge and causes the transmitter to send the triggering signal to the acoustic decoy.

Abstract: A method for identification of one or more launched objects obscured by debris objects within a debris field comprises: directing one or more sensor pulses at the debris field to obtain a plurality of sensor images; identifying objects within the debris field based on the sensor images; determining acceleration characteristics for each of the identified objects within the debris field based on the sensor images; identifying objects exhibiting free fall acceleration characteristics as debris objects; and identifying objects exhibiting centripetal acceleration characteristics as the one or more launched objects.

Abstract: A radar installation searches a limited volume within view, such as a covariance ellipsoid where a target is expected to be found based on a cue from a remote radar. The radar activates beams selected from an angularly diverging array of beams spanning the azimuth and elevation of an acquisition face whose area increases with range from the radar. A controller projects the search volume relative to the acquisition face, for selecting beam positions intersecting the search volume, and activates beams for a time interval that determines maximum range. A coordinate transformation is effected, so that with decreasing range, the angular divergence between projected points of the search volume is correspondingly increased, including points tangent to outer edges of the ellipsoid. The search volume accurately corresponds to the covariance ellipsoid by accounting for perspective in this way, reducing the time needed to examine the search volume for the target.

Abstract: A method and system is disclosed for tracking object clusters. The method comprises obtaining a first sensor image and a second sensor image. Angular measurements between objects of the first sensor image are determined. Angular measurements between objects of the second sensor image are also determined. Angular measurements from the first sensor image are compared to angular measurements of the second image, and correlated object clusters are identified. The sensor system includes a command and decision unit that receives a first sensor image and a second sensor image. The command and decision unit determines angular measurements for the first sensor image, and determines angular measurements for the second sensor image. The command and decision unit compares the angular measurements for the first sensor image to the angular measurements for the second sensor image, and identifies correlated object clusters based on the comparison.

Abstract: Methods are disclosed for obtaining a cued radar acquisition volume. The method employs uncertainties (i.e., errors) represented by a covariance, and a method of finding the minimum volume defined by range, azimuth, and elevation limits that enclose the covariance, and uses a perspective projection of the errors to provide an accurate calculation of the cued acquisition volume. The three-dimensional problem is first reduced to two dimensions by parallel projection onto the range-transverse and range-elevation planes. Then perspective projection of the two dimensional parallel projections is performed. The disclosed method reduces the complexity of three dimensional perspective projection by preceding perspective projection with parallel projection, which greatly simplifies the problem and allows a simple and easily calculated solution.