Abstract: Systems, methods, and apparatus for processing a signal using a non-uniform antenna array are disclosed. In one aspect, a receiver apparatus for processing high frequency signals is provided. The receiver apparatus may comprise an antenna array including a plurality of antenna elements. The plurality of antenna elements may include a first antenna element and a remainder of the plurality of antenna elements. The remainder of the plurality of antenna elements may be uniformly spaced apart from one another by a first distance and arranged in a substantially linear orientation. The remainder of the plurality of antenna elements may include a second antenna element spaced apart from the first antenna element by a second distance. The second distance may be different than the first distance.

Abstract: Methods for improving multiple signal reception using receiver diversity in the context of a wideband radar and communications receiver. The method allows for improved signal reception as well as improved angle of arrival estimation. A first approach uses a method that improves angle of arrival estimation while using the standard diversity technique of selection combining. A second approach uses a method of equalization of the signal rather than equalization of the channel to both improve the signal SNR over standard selection combining and further improve the angle of arrival estimate over the first approach.

Abstract: Systems and methods which use adjunct signals from a remote highly stable clock to enhance performance of a digital wideband receiver equipped with a less stable local clock system. The digital wideband receiver includes an analog-to-digital converter (ADC) and an adjunct receiver system connected to the output of the ADC. The adjunct receiver system includes matched filters and circuitry configured to generate an interpolation coefficient vector based on the matched filter outputs. The adjunct receiver system further includes an interpolating filter which is configured to remove jitter from the digitized samples output by the ADC using the interpolation coefficient vector.

Abstract: A computer-implemented method for processing radar information comprises receiving synthetic aperture radar (SAR) data that specifics a sequence of radar acquisitions of a target area taken over a particular acquisition time. The method comprises forming a plurality of sub-aperture images, wherein each sub-aperture image is associated with radar acquisitions of the target area taken over a particular interval of the acquisition time. The method further comprises determining, based on the plurality of sub-aperture images, velocities associated with one or more target objects moving within the target area; and generating an image associated with the SAR data that depicts the one or more target objects and the velocities associated with one or more target objects.

Abstract: Systems and methods for direct signal down-conversion and decimation in a digital receiver. The digital receiver produces a decimated passband version of the signal without the problems associated with use of digital mixers. The digital receiver includes a passband-to-passband decimator/down-converter that implements an algorithm which takes the signal band (frequency and bandwidth or lower and upper frequencies) where a signal is present and produces a decimation rate and phase for use by a low-pass mixer-free down-conversion. The digital receiver technology may be efficiently implemented on a digital signal processor or field-programmable gate array.

Abstract: A collision avoidance system includes a monopulse radar antenna array of monopulse radar antenna segments mounted to a vehicle with respective fixed fields of view. Each monopulse radar antenna segment comprises a comparator network configured to form a sum signal representing a summation of return signals and a first difference signal representing a first difference of the return signals. The system further includes a user interface configured to present information in a form perceptible to a person operating the vehicle and a radar antenna array controller configured to calculate a range of the object and a first (azimuth) angle of arrival of the return signal from the object. The comparator network is further configured to form a second difference signal which the radar antenna array controller uses to calculate a second (elevation) angle of arrival.

Abstract: Systems and methods for estimating frequency and bandwidth of unknown signals using learned features of a filter pair for the purpose of detecting, separating and tracking these signals in an electronic receiver. The techniques could be part of a signal cueing system that initiates signal detection, separation and tracking or a signal separation and tracking system which is initialized by the cueing system and adaptively updates frequency and bandwidth estimates so as to continuously separate and track signals after initial detection. The methodology is to train the filter responses using machine learning by creating a grid of training data based on signal examples that cover a span of frequencies and bandwidths. The system estimates frequency and bandwidth in real time, inputs those estimates into interpolating lookup tables to retrieve filter coefficients, and provides those filter coefficients to a tunable tracking filter.

Abstract: Methods for improving multiple signal reception using receiver diversity in the context of a wideband radar and communications receiver. The method allows for improved signal reception as well as improved angle of arrival estimation. A first approach uses a method that improves angle of arrival estimation while using the standard diversity technique of selection combining A second approach uses a method of equalization of the signal rather than equalization of the channel to both improve the signal SNR over standard selection combining and further improve the angle of arrival estimate over the first approach.

Abstract: A receiver includes an antenna block configured to transduce impinging electromagnetic signals into electrical signals; a signal conditioning block configured to condition electrical signals received from the antenna block; and a down-converter block configured to down-convert conditioned electrical signals received from the signal conditioning block. The down-converter block comprises a plurality of signal channels. The receiver further includes a plurality of analog-to-digital converters (ADCs) respectively connected to the signal channels of the down-converter block; and a field-programmable gate array (FPGA). The FPGA is configured to program the down-converter block by selecting a set of mixer frequencies and a set of bandwidths designed to remove interference signals in each signal channel. The selections are calculated to mitigate reductions in dynamic range in the ADCs due to interference.

Abstract: A method and apparatus for generating a frequency comb. A sine wave comprising samples is generated at a selected sampling rate and a selected increment corresponding to a number of samples for a period of the sine wave using a lookup table or a CORDIC algorithm. The sine wave is processed by a universal differential equation to generate the frequency comb. Characteristics of the frequency comb generated from the sine wave are controlled by changing the sampling rate and the increment.

Abstract: A method and apparatus for generating a frequency comb. A sine wave comprising samples is generated at a selected sampling rate and a selected increment corresponding to a number of samples for a period of the sine wave using a lookup table or a CORDIC algorithm. The sine wave is processed by a universal differential equation to generate the frequency comb. Characteristics of the frequency comb generated from the sine wave are controlled by changing the sampling rate and the increment.

Abstract: A method, apparatus, and system for counting events. a set of quantum registers is reset. A Hadamard operator is applied to the set of quantum registers. A quantum instruction is executed on the set of quantum registers, wherein the quantum instruction incorporates a function for an event vector comprising events identified by bits. The Hadamard operator is applied to the set of quantum registers after executing the quantum instruction. The set of quantum registers is measured to form a measurement of the set of quantum registers. An approximate count of the events is determined using the measurement of the set of quantum registers.

Abstract: An air cleaner arrangement or assembly is provided. The air cleaner arrangement includes a serviceable filter cartridge. The air cleaner assembly also includes an arrangement for positioning the filter cartridge into a preferred, sealing, orientation and for securing the filter cartridge in that location. Preferred serviceable filter cartridges are provided, as well as methods of assembly and use.

Abstract: Systems and methods for direct signal down-conversion and decimation in a digital receiver. The digital receiver produces a decimated passband version of the signal without the problems associated with use of digital mixers. The digital receiver includes a passband-to-passband decimator/down-converter that implements an algorithm which takes the signal band (frequency and bandwidth or lower and upper frequencies) where a signal is present and produces a decimation rate and phase for use by a low-pass mixer-free down-conversion. The digital receiver technology may be efficiently implemented on a digital signal processor or field-programmable gate array.

Abstract: Systems and methods which use adjunct signals from a remote highly stable clock to enhance performance of a digital wideband receiver equipped with a less stable local clock system. The digital wideband receiver includes an analog-to-digital converter (ADC) and an adjunct receiver system connected to the output of the ADC. The adjunct receiver system includes matched filters and circuitry configured to generate an interpolation coefficient vector based on the matched filter outputs. The adjunct receiver system further includes an interpolating filter which is configured to remove jitter from the digitized samples output by the ADC using the interpolation coefficient vector.

Abstract: Systems and methods for tracking swarms of flying objects for collision avoidance using area-scanning optical systems. Images of the volume of space forward of an aircraft in flight are captured using one or more cameras and then the images are processed to determine whether the image data indicates the presence of a swarm. The camera-based collision avoidance system is configured to detect and angularly track small objects flying in a swarm at sufficiently far ranges to cue or alert the flight control system onboard an autonomous or piloted aircraft to avoid the swarm. A swarm angle tracking algorithm is used to recognize swarms of flying objects that move in unison in a certain direction by detecting a consistent characteristic of the pixel values in captured images which is indicative of swarm motion.

Abstract: Systems and methods for tracking swarms of flying objects for collision avoidance using area-scanning optical systems. Images of the volume of space forward of an aircraft in flight are captured using one or more cameras and then the images are processed to determine whether the image data indicates the presence of a swarm. The camera-based collision avoidance system is configured to detect and angularly track small objects flying in a swarm at sufficiently far ranges to cue or alert the flight control system onboard an autonomous or piloted aircraft to avoid the swarm. A swarm angle tracking algorithm is used to recognize swarms of flying objects that move in unison in a certain direction by detecting a consistent characteristic of the pixel values in captured images which is indicative of swarm motion.

Abstract: Systems and methods for forming optimized transmit or receive beams using an array antenna. A parallelized beam forming algorithm is employed that allows the beam to be optimized to increase performance over typical time-delay beam steering. The parallelized beam forming optimization algorithm is based on a limited-memory Broyden-Fletcher-Goldfarb-Shanno algorithm with bound constraints. Using a matrix form of both the beam and beam gradient functions allows parallel optimization through beam matching against a designed target beam. Because the optimization is both efficient and parallelizable, beams may be optimized beams in real time. Hence the optimization technique may be implemented directly as part of a beam steering controller.

Abstract: An aircraft includes a fuselage, a first wing coupled to the fuselage and including a first wingtip that is movable relative to the fuselage during flight, and a second wing coupled to the fuselage, opposite the first wing, and including a second wingtip that is movable relative to the fuselage and relative to the first wingtip during flight. The aircraft also includes a first camera mounted to the first wingtip of the first wing and a second camera mounted to the second wingtip of the second wing. The aircraft further includes a processing unit configured to determine a real-time distance between the first camera and the second camera as the first camera and the second camera move relative to each other and relative to the fuselage during flight.

Abstract: Systems and methods for estimating frequency and bandwidth of unknown signals using learned features of a filter pair for the purpose of detecting, separating and tracking these signals in an electronic receiver. The techniques could be part of a signal cueing system that initiates signal detection, separation and tracking or a signal separation and tracking system which is initialized by the cueing system and adaptively updates frequency and bandwidth estimates so as to continuously separate and track signals after initial detection. The methodology is to train the filter responses using machine learning by creating a grid of training data based on signal examples that cover a span of frequencies and bandwidths. The system estimates frequency and bandwidth in real time, inputs those estimates into interpolating lookup tables to retrieve filter coefficients, and provides those filter coefficients to a tunable tracking filter.