Abstract: Methods and systems for suppressing clutter, for example, ground clutter, in radar systems are provided. The methods and systems can be employed in radar systems having an antenna system and at least two receive beams, for example, a main beam and an auxiliary beam. The methods include receiving data streams from each of the at least two receive beams, where each data stream is associated with range bins and include data representing clutter, and, before or after Doppler filtering, generating an adaptive weight from summations of the data streams for each of the range bins, and applying the generated weight to at least one of the data streams to provide Doppler filtered and spatially nulled data streams that can be used to more accurately identify targets, such as, aircraft.

Abstract: An adaptive finite impulse response (FIR) filter for filtering an I/Q data stream having a sample period. The FIR filter comprises at least one sample-period tap delay configured to delay the I/Q data stream by an integer multiple of the sample period of the I/Q data stream, and at least one sub-sample-period tap delay configured to delay the I/Q data stream by a non-integer multiple of the sample period of the I/Q data stream. A set of adaptive weights is provided and configured to weight samples of the delayed I/Q data stream. An adder is responsive to the weighted samples and configured to combine the weighted samples of the delayed I/Q data streams to generate a filtered I/Q data stream.

Abstract: An auxiliary receiver implemented method of providing to a host RF system one or more frequency and bandwidth recommendation for a minimal electromagnetic interference (EMI) near-future transmission, the method including the steps of receiving signals on an antenna such as an omni-directional antenna in a band of operation of the host system 360 degrees in azimuth; analyzing the received signals in the auxiliary receiver; performing a statistical analysis in the auxiliary receiver to predict the one or more frequency and bandwidth recommendation for a minimal EMI near-future transmission; and providing one or more frequency and bandwidth recommendations to the host system.

Abstract: A method of canceling sinusoidal interference from a received signal includes identifying a block of signal-free data containing sinusoidal interference. A model of the significant interference in the selected data block is constructed, scaled to subsequent data blocks and used to remove sinusoidal interference signals from the overall received signal.

Abstract: A method for adaptively matching the frequency response of two channels of a received signal includes the steps of receiving a main RF signal on a main antenna, sampling the main RF signal at a sample rate, delaying the sampled main RF signal by a multiple of a sample period, wherein the sample period is the inverse of the sample rate, receiving at least one other RF signal on at least one other auxiliary antenna, sampling each of the at least one other RF signal at the sample rate, filtering each of the at least one other sampled RF signal utilizing an adaptive finite impulse response (FIR) filter having at least one sub-sample-period time delay, and combining the sampled main RF signal with each of the filtered at least one other sampled RF signals.

Abstract: A system and method of providing to a beamformer a modified complex beam steering vector includes collecting subarray I/Q samples from a plurality of subarrays receiving clutter, performing coherent integration of the subarray I/Q samples to increase the CNR, adaptively modifying a complex beam steering vector to form a null in the direction of the received clutter, and outputting to a beamformer the modified complex beam steering vector. The beamformer receives complex I/Q data samples representing a radar signal containing near-horizon clutter and applies the modified beam steering vector to generate a beamformed signal having an elevated mainlobe and a spatial sidelobe null in the direction of the received clutter.

Abstract: A method of canceling impulsive interference from a communications signal is provided. The method includes identifying an impulse interference contained in the communications signal, generating a model of impulse interference, matching the model in at least one of amplitude, phase and envelope time delay to the identified impulse interference, and cancelling the identified impulse interference by subtracting the matched model from the identified impulse interference.

Abstract: A system and method for enhancing a magnetic communication signal is provided. A multi-element receiver is used to generate a plurality of input signals. A set of weights is generated using, for example, a calculated covariance of the plurality of input signals, and applied to the signals. The weights are used to generate a single output signal representing a weighted sum of the input signals.

Abstract: A method of canceling sinusoidal interference from a received signal includes identifying a block of signal-free data containing sinusoidal interference. A model of the significant interference in the selected data block is constructed, scaled to subsequent data blocks and used to remove sinusoidal interference signals from the overall received signal.

Abstract: A system and method for enhancing a magnetic communication signal is provided. A multi-element receiver is used to generate a plurality of input signals. A set of weights is generated using, for example, a calculated covariance of the plurality of input signals, and applied to the signals. The weights are used to generate a single output signal representing a weighted sum of the input signals.

Abstract: A method of canceling impulsive interference from a communications signal is provided. The method includes identifying an impulse interference contained in the communications signal, generating a model of impulse interference, matching the model in at least one of amplitude, phase and envelope time delay to the identified impulse interference, and cancelling the identified impulse interference by subtracting the matched model from the identified impulse interference.

Abstract: A polygonal cylindrically shaped phased array antenna forming a radar has an active aperture that focuses in any of one or more angular azimuth directions without inertia. It further includes adjacent multiple similar polygonal staves joined along their vertical edges to form a right regular polygonal cylinder. Each stave is further decomposed into flat panels, wherein each panel has a plurality of antenna elements positioned in a regular rectangular or triangular lattice. Each panel contains a beam forming network that electronically forms and steers an electromagnetic beam for purposes of transmission and subsequent reception. The panels optionally may operate as autonomous radars which when coherently combined form multiple larger antenna apertures, each capable of operating autonomously. A switching network allows transmit power and all requisite radar and control signals to be sent to and received from a selected set of panels anywhere on the polygonal cylinder.

Abstract: A method for reducing the interference between a source transmitting pulses and equipments having nominal bandwidths which are outside the nominal bandwidth of the transmitted pulses, but which respond to sideband energy of the pulses. Phase perturbations are applied to the edges of the pulses produced by the source, to thereby tend to null the sideband energy lying in the nominal bandwidth of the equipments occupying the adjacent nominal bandwidths.

Abstract: A method for reducing the interference between a source transmitting pulses and equipments having nominal bandwidths which are outside the nominal bandwidth of the transmitted pulses, but which respond to sideband energy of the pulses. Phase perturbations are applied to the edges of the pulses produced by the source, to thereby tend to null the sideband energy lying in the nominal bandwidth of the equipments occupying the adjacent nominal bandwidths.

Abstract: A monopulse precision landing or other land-based radar system uses an array antenna and a beamformer to produce sum, azimuth difference and elevation difference beams relative to the array. The rows and columns of the array are skewed relative to the horizontal for tending to reduce the effects of multipath propagation on altitude estimates. A coordinate converter converts target information from the skewed antenna coordinates to ordinary vertical and horizontal coordinates.

Abstract: A method for reducing the interference between a source transmitting pulses and equipments having nominal bandwidths which are outside the nominal bandwidth of the transmitted pulses, but which respond to sideband energy of the pulses. Phase perturbations are applied to the edges of the pulses produced by the source, to thereby tend to null the sideband energy lying in the nominal bandwidth of the equipments occupying the adjacent nominal bandwidths.

Abstract: A method for reducing the interference between a source transmitting pulses and equipments having nominal bandwidths which are outside the nominal bandwidth of the transmitted pulses, but which respond to sideband energy of the pulses. Phase perturbations are applied to the edges of the pulses produced by the source, to thereby tend to null the sideband energy lying in the nominal bandwidth of the equipments occupying the adjacent nominal bandwidths.

Abstract: A monopulse precision landing or other land-based radar system uses an array antenna and a beamformer to produce sum, azimuth difference and elevation difference beams relative to the array. The rows and columns of the array are skewed relative to the horizontal for tending to reduce the effects of multipath propagation on altitude estimates. A coordinate converter converts target information from the skewed antenna coordinates to ordinary vertical and horizontal coordinates.

Abstract: A monopulse radar system generates elevation and azimuth difference monopulse estimates of the location of targets in each range cell, where the target may be either a single or plural target, each of which is made up of multiple scattering sources. Each azimuth-elevation estimate is based on a transmitted pulse or burst at a given frequency, different from other frequencies in a set of pulses or bursts. A test statistic is generated for each set. The statistic relates to the shape in an azimuth-elevation plane of the cluster of estimates. The test statistic is compared with a threshold to decide whether a single target or plural targets exist in the range cell.