Abstract: A method and apparatus for providing a standalone anti-jamming (AJ) nuller-beamformer. Signals from an antenna array include a sum of Global Navigation Satellite System (GNSS) signals and jamming signals from a plurality of spatial sources. A front end is configured to amplify, filter, down-convert, and sample the input signals which are then filtered, downconverted, and decimated prior to frequency-domain and time-domain partitioning. Weights are computed and applied for spatial nulling of jamming signals in each frequency bin for the partitioned signals. Frequency and time-domain reconstruction generates a reconstructed signal with suppressed jamming.

Abstract: A technology is described for mitigating global positioning system (GPS) spoofer signals. A potentially spoofed GPS signal received via an antenna coupled to a GPS receiver can be identified. The potentially spoofed GPS signal can be applied to a spoofer signal nulling loop to generate a set of spoofer nulling weights. The set of spoofer nulling weights can produce a direction vector associated with the potentially spoofed GPS signal. The direction vector can be compared to a beamsteering vector. The potentially spoofed GPS signal can be determined as being a spoofer GPS signal when a misalignment between the direction vector and the beamsteering vector is above a defined threshold. The spoofer GPS signal can be converted to a spoofer mitigation signal that is applied to satellite track channels of the GPS receiver. The spoofer mitigation signal can produce a spatial null in a direction of the spoofer GPS signal.

Abstract: A system for multi-ship geolocation of a signal emitter of interest uses differential GPS (DGPS) to determine the relative positions of two or more receivers in order to determine baseline vectors between them. The geolocation of the signal emitter is then determined as a function of the baseline vectors. The use of DGPS allows for more efficient and useful geometries between the receivers as two receivers can both be in a mainlobe of an emitted signal and still provide increased geolocation accuracy.

Abstract: A technology is described for mitigating global positioning system (GPS) spoofer signals. A potentially spoofed GPS signal received via an antenna coupled to a GPS receiver can be identified. The potentially spoofed GPS signal can be applied to a spoofer signal nulling loop to generate a set of spoofer nulling weights. The set of spoofer nulling weights can produce a direction vector associated with the potentially spoofed GPS signal. The direction vector can be compared to a beamsteering vector. The potentially spoofed GPS signal can be determined as being a spoofer GPS signal when a misalignment between the direction vector and the beamsteering vector is above a defined threshold. The spoofer GPS signal can be converted to a spoofer mitigation signal that is applied to satellite track channels of the GPS receiver. The spoofer mitigation signal can produce a spatial null in a direction of the spoofer GPS signal.

Abstract: GPS aided precision timing uses GPS to generate synchronized timing pulses by various nodes. One of the nodes is designated as a master node and the remaining nodes are designated as auxiliary nodes. Each node tracks the carrier phases of satellite signals transmitted by a plurality of GPS satellites relative to a carrier phase of a reference oscillator in the respective node. The master node provides the tracked phase measurements along with its position information to all of the auxiliary nodes. Each auxiliary node determines the phase offset of its reference oscillator relative to the reference oscillator of the master node to “align” its phase to the phase of the master node. The phase of a time pulse signal generator in each node is then aligned to the phase of its reference oscillator for generating synchronized timing pulses based on the aligned phases.

Abstract: GPS aided precision timing uses GPS to generate synchronized timing pulses by various nodes. One of the nodes is designated as a master node and the remaining nodes are designated as auxiliary nodes. Each node tracks the carrier phases of satellite signals transmitted by a plurality of GPS satellites relative to a carrier phase of a reference oscillator in the respective node. The master node provides the tracked phase measurements along with its position information to all of the auxiliary nodes. Each auxiliary node determines the phase offset of its reference oscillator relative to the reference oscillator of the master node to “align” its phase to the phase of the master node. The phase of a time pulse signal generator in each node is then aligned to the phase of its reference oscillator for generating synchronized timing pulses based on the aligned phases.

Abstract: Precision surgical jamming of a target located at a distance uses GPS to coherently focus the jamming energy transmitted from a plurality of nodes. One of the nodes is designated as a master node and the remaining nodes are designated as auxiliary nodes. Each node tracks the carrier phases of satellite signals transmitted by a plurality of GPS satellites relative to a carrier phase of a reference oscillator in the respective node. The master node provides the tracked phase measurements along with its position information to all of the auxiliary nodes. The auxiliary nodes determine the phase offset of its reference oscillator relative to the reference oscillator of the master node based on the transmitted data. The transmit phase of a jammer transmitter in each of the nodes is then aligned to the phase of the reference oscillator to transmit a coherent focused beam to a distant target.

Abstract: A dynamic weight processing system. The inventive system includes a first circuit for receiving an input signal and a second circuit for filtering the input signal with dynamic weights to provide a weighted signal. In an illustrative embodiment, the dynamic weights are finite impulse response filter correlation coefficients that are dynamically generated based on a pseudo-noise code. The system may also include a dynamic weight generator that generates the dynamic weights by combining weight values stored in a lookup table in a manner dependent on the pseudo-noise code. The weighted signal may be further processed to generate nulling and beamsteering weights for the input signal. In a more specific implementation for a GPS (Global Positioning System) application, the received signal is partitioned into space frequency adaptive processing (SFAP) bands and space time adaptive processing (STAP) is performed within the SFAP bands.

Abstract: Precision surgical jamming of a target located at a distance uses GPS to coherently focus the jamming energy transmitted from a plurality of nodes. One of the nodes is designated as a master node and the remaining nodes are designated as auxiliary nodes. Each node tracks the carrier phases of satellite signals transmitted by a plurality of GPS satellites relative to a carrier phase of a reference oscillator in the respective node. The master node provides the tracked phase measurements along with its position information to all of the auxiliary nodes. The auxiliary nodes determine the phase offset of its reference oscillator relative to the reference oscillator of the master node based on the transmitted data. The transmit phase of a jammer transmitter in each of the nodes is then aligned to the phase of the reference oscillator to transmit a coherent focused beam to a distant target.

Abstract: A dynamic weight processing system. The inventive system includes a first circuit for receiving an input signal and a second circuit for filtering the input signal with dynamic weights to provide a weighted signal. In an illustrative embodiment, the dynamic weights are finite impulse response filter correlation coefficients that are dynamically generated based on a pseudo-noise code. The system may also include a dynamic weight generator that generates the dynamic weights by combining weight values stored in a lookup table in a manner dependent on the pseudo-noise code. The weighted signal may be further processed to generate nulling and beamsteering weights for the input signal. In a more specific implementation for a GPS (Global Positioning System) application, the received signal is partitioned into space frequency adaptive processing (SFAP) bands and space time adaptive processing (STAP) is performed within the SFAP bands.

Abstract: A dynamic weight generator. The inventive generator includes a first memory for storing a PN code; a second memory for storing a plurality of weights, the second memory being coupled to the first memory whereby data output by the first memory is used to address data stored in the second memory; and a correlator for multiplying an input signal by data output by the second memory. In the illustrative embodiment, the weights are finite impulse response filter correlation coefficients. The correlator includes two multipliers. The first of the multipliers is coupled to a source of an in-phase component of the input signal. The second of the multipliers is coupled to a source of a quadrature component of the input signal. The outputs of the multipliers are summed. In the illustrative application, the input signal is a GPS signal. For this application, the inventive teachings are implemented in a signal processing system adapted to receive a GPS signal and provide in-phase and quadrature signals in response thereto.

Abstract: A post-correlation nulling circuit (10) derives from a narrowband jammer a replica of the baseband jammer noise which is used to adaptively cancel the jammer noise waveform in the receiver baseband after PN processing, thus allowing the adaptive antenna spatial nulling to concentrate on canceling wideband jammers.

Abstract: A system for processing modulated signals received, together with at least one interference signal, by an array of antenna elements in a communications receiver. The method of the invention includes demodulating the received signals, and processing the demodulated signals to produce an output signal that is substantially free of any interference signals, while at the same time effectively steering the antenna pattern produced by the array of elements, to move any spurious nulls in the pattern away from a source of information signals. This results in avoidance of any cycle slipping problems that might otherwise arise in receiver tracking control loops, and has the added benefit of significantly improving performance as measured by the signal-to-noise ratio.

Abstract: A null processing receiver apparatus that receives and combines together a number of modulated information signals in such a fashion that an interference or jamming signal superimposed on each received signal is substantially eliminated from the combined signal. The apparatus first demodulates each received signal to baseband, to produce a primary demodulated signal and one or more auxiliary demodulated signals. The apparatus then appropriately weights the one or more auxiliary signals and sums together the weighted signals with the primary signal to produce a sum signal in which the interference is substantially nulled out. The weighting is based on a cross-correlation of the sum signal with the baseband signals themselves.

Abstract: An apparatus and method for providing pointing information in accordance with a reference signal produced by at least one GPS satellite, including a pair of antenna elements for individually receiving the reference signal produced by at least one GPS satellite and for producing output signal in accordance with the received reference signal, the pair of antenna elements spaced from each other a fixed distance along a line to provide for a difference in phase between the reference signal as received at one antenna relative to the other antenna in accordance with the pointing angle of the pair of antennas along the line relative to the direction of the GPS satellite, means responsive to the output signals produced by the pair of antenna elements for producing a phase difference signal in accordance with the difference in phase between the reference signal as received at the one antenna relative to the other antenna, and means responsive to the phase difference signal produced by the last mentioned means for calc