Hughes Aircraft Company

Other

Raytheon Company

Wilbur W Eaton

Kirk K Kohnen

Ben R Breed

Allen K Lo

Eric K Slater

Harold C Gilbert

James W Casalegno

A system for passively sensing low frequency (5 Hz to 50 kHz) EM emanations from vehicles and classifying them on that basis. A temporal frequency response is computed for the sensed EM emanations. Harmonic, non-harmonic and temporal features are extracted from the response and used to classify the vehicle. In the preferred embodiment, the temporal frequency response is displayed as a time, frequency and intensity plot, from which a technician visually extracts these features. The features can then be used either to determine a 'signature' for classifying the vehicle or to determine specific characteristics which, in turn, can be used to classify the vehicle. Alternately, the feature extraction and classification can be performed by an automated classifier.

Passive vehicle classification using low frequency electro-magnetic

A target's magnetic dipole includes both a permanent component and an induced component that is caused by the interaction of the target at a given heading with the ambient magnetic field. In order to accurately classify targets, a library of characterization matrices is built for a plurality of candidate targets. The matrices characterize what the magnetic dipoles would be in a given ambient magnetic field at a particular heading. In practice, some localization algorithm is used to provide a target's magnetic dipole and heading. Magnetic dipoles for each of the candidate targets are predicted using the target's heading, the ambient magnetic field, and the characterization matrices. The target is then classified as the candidate target(s) providing the best match to the target's measured magnetic dipole.

Magnetic dipole target classifier and method

Self leveling apparatus that includes a frame, a device that is to be leveled, and a leveling mechanism such as a double ring gimbal having an inner gimbal ring and an outer gimbal ring. The outer gimbal ring is secured to the frame and the inner gimbal ring is secured to the device and to the outer ring. The inner ring comprises a viscous or preloaded bearing that allows the device to swing around an inner ring axle to thereby level itself in that axis and prevent spurious movement of the device. The outer gimbal ring and inner gimbal ring are attached by outer axles that comprise a viscous or preloaded bearing that allow the inner gimbal ring to swing around the outer axles thereby level the inner gimbal ring in that axis and prevent spurious movement of the device. A disclosed embodiment of the invention includes a magnetometer sensor that is coupled to signal processing and telemetry electronics and a power source that are leveled to keep axes of the sensor oriented along horizontal and vertical axes.

Self leveling sensor/device package

A synthetic array comprising a moving magnetic sensor that provides a signal representative of an array of magnetic sensors is coupled to a digital signal processor is used to break a magnetic dipole field into its components, and a magnetic signature of the present magnetic field is created. Predicted dipole signatures are precomputed for multiple magnetic orientations of the dipole at each of a plurality of range locations, expressed in terms of Anderson functions, which are a set of equations that decompose the magnetic field in each of the magnetic response locations, and are stored in a lookup table for reference. Input data measured by the moving synthetic array are processed and each magnetic value is predicted to process against background noise. A long term time average consistent with the relative motion of the dipole is computed using bandpass filtering of the signals from the synthetic array. The bandpass filtered data is used to update the predicted data so that anomalies and other non-dipole data is removed from the signals that are processed. The data are then expressed in terms of Anderson functions. The data are matched faltered, wherein it is correlated with the stored precomputed predicted dipole signatures. The correlation yields a set of values that is then thresholded. If a dipole is present at any of the locations, then the correlated normalized value computed as stated above will be higher than the chosen threshold. The dipole locations that are above the threshold are then displayed on a monitor showing the relative location and dipole orientation.

Synthetic aperture array dipole moment detector and localizer

A dipole moment detection and localization process and apparatus in which the processing is applied to a single linear array adapted to sense magnetic dipoles, and wherein data from the sensors are processed as if it were derived from sets of subarrays of sensors. The apparatus comprises a linear sensor array whose output is processed by separate dipole moment detection and location processors, or a single processor that provides for parallel processing operation. Data from the plurality of subarrays of sensors are processed in terms of Anderson functions and are correlated. The individual outputs of each processor, or parallel processing portion, is coupled to a multiplier that is adapted to correlate the signals. The dot product of these two correlated output signals is then formed to yield data that is thresholded and displayed.

Split array dipole moment detection and localization

An array of magnetic sensors and a digital signal processor are used to break a target magnetic dipole field into its components, and a magnetic signature of the present magnetic field is created. Predicted target signatures are precomputed for multiple magnetic orientations of the dipole at each of a plurality of range locations, expressed in terms of Anderson functions, which are a set of equations that decompose the magnetic field in each of the magnetic response locations, and are stored in a lookup table for reference. Input data measured by the sensors are processed and each sensor's magnetic value is predicted to process against background noise using the other sensors of the array. A long term time average consistent with the relative motion of the target is computed using bandpass filtering of the signals from the sensor array. The bandpass filtered data is used to update the predicted data so that anomalies and other non-target data is removed from the signals that are processed. The data are then expressed in terms of Anderson functions. The data are matched filtered, wherein it is correlated with the stored precomputed predicted target signatures. The correlation yields a set of values that is then thresholded. If a target is present at any of the locations, then the correlated normalized value computed as stated above will be higher than the chosen threshold. The target locations that are above the threshold are then displayed on a monitor showing the relative location and dipole of orientation.

Dipole moment detection and localization

An alignment process is applied to each sensor of an array of three axis magnetic sensors to electronically align the three axes of each sensor after the array has been deployed. The alignment process compensates for each sensor not being aligned perfectly with the earth's N-S, E-W and vertical magnetic field components. A field registration process is applied to each sensor of the array that uses a dipole moment detection and localization process and the alignment process combined with a known calibrated dipole source to define the shape of the array. The present invention improves the performance of the array of sensors in detecting magnetic anomalies by digitally compensating for sensor-to-sensor nonalignment and magnetic interferers within interfering range. The alignment process electronically aligns the three axes of each of the sensors to gain maximum performance from the sensor array. Using digital signal processing techniques reduces the physical deployment requirements on the sensors and their relative positions. The alignment process allows the use of three axis vector magnetometers in a distributed field with out having to lay each sensor in perfect alignment with the earth's three magnetic axis. This simplifies the deployment requirements and allows for maximizing the system performance.

Growing community of inventors

Placentia, CA, United States of America

Wilbur W Eaton