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: A method of operating a pulse-Doppler radar system includes the steps of generating a plurality waveforms, with each waveform comprising a plurality of pulses generated with a staggered pulse repetition frequency (PRF) from pulse to pulse. Received reflected return signals from the generated plurality of waveforms are filtered by a plurality of Doppler filters that span an entire required Doppler visibility range.

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 compensating for transmitter instability of a radar system is provided. The method includes the steps of transmitting at least one electromagnetic pulse and directly measuring at least one characteristic of the transmitted pulse. A comparison is made between the at least one measured characteristic of the transmitted pulse to a reference pulse characteristic. The results of this comparison are used to generate a complex weight for the at least one electromagnetic pulse. The weight is applied to the received return of the at least one electromagnetic pulse.

Abstract: A system for suppressing clutter in a radar system is provided. The system includes an antenna configured to receive radar signals containing clutter and a digital receiver adapted to convert the radar signals received by the radar arrays to complex I/Q samples. These I/Q samples are provided to a Doppler filter bank comprising a plurality of Doppler filters for filtering the pulse compressed data into Doppler bins representative of range values according to Doppler frequency. The system further includes at least one processor for comparing the output of each of the plurality of Doppler filters types to respective background clutter maps, and identifying the Doppler filter which outputs the radar return signal with the greatest magnitude over the clutter map. Once identified, target detection operations may be performed on the output of the identified Doppler filter.

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 and system for suppressing unwanted signals when detecting objects of interest in a detection system comprising an antenna system and two or more receive beams. A background map is created by range, azimuth and Doppler. Locations within the residual clutter in the moving Doppler bins are selected for nulling. Adaptive nulling is performed independently on each Doppler bin of the selected location to enable Doppler-specific spatial nulling for the same range and azimuth bin.

Abstract: In a radar system using a radar clutter map comprising a plurality of range-azimuth cells containing parameter data values indicative of time averaged echo returns for affecting alarm threshold levels at range-azimuth locations scanned by the radar system antenna, a method for detecting comprising the steps of obtaining from the radar clutter map a first parameter data value associated with a given cell under test (CUT); determining a second parameter data value using parameter data values of other cells from the plurality of range-azimuth cells from the radar clutter map; comparing the first parameter data value associated with the CUT with the second parameter data value; and generating a signal indicative of a target detection when the first parameter data value exceeds the second parameter data value by a given threshold corresponding to a target false alarm rate.

Abstract: A T/R module utilizes a low noise amplifier in both the transmit and receive modes. In this manner the low noise amplifier enables one to provide a T/R module which has reduced prime power and lower weight and particularly useful in airship radar systems and spaced based radar systems. The low noise amplifier is switched between a receive and a transmit mode by switching mechanism which in the receive mode enables the antenna to be directed to the input of the low noise amplifier with the output of the low noise amplifier directed to a phase shifter and attenuator. The switching operates in a transmit mode where the output of the low noise amplifier is connected to the input of the antenna while the input of the low noise amplifier is now connected to the phase shifter and attenuator for providing a transmit signal. The invention has an additional benefit of enabling linear Class A operation in the transmit mode in both radar and communication systems supporting beam shaping and waveform shaping capabilities.

Abstract: In a radar system that detects relatively fast moving targets using a radar clutter map comprising a plurality of range-azimuth cells containing parameter data values indicative of time averaged echo returns for affecting alarm threshold levels at range-azimuth locations scanned by the radar system antenna, a method for detecting relatively slow moving targets in a substantially homogeneous surveillance region, the method comprising the steps of obtaining from the radar clutter map a value corresponding to parameter data of a given cell under test (CUT); determining a second parameter data value using parameter data values of other cells from the plurality of range-azimuth cells from the radar clutter map; comparing the parameter data value of the CUT with the second parameter data value; and generating a signal indicative of a target detection when the CUT parameter data value exceeds the second parameter data value by a given threshold corresponding to a target false alarm rate.

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.