Northrop Grumman Systems Corporation

Northrop Grumman Guidance and Electronics Company, Inc.

Litton Systems, Inc.

Exelis Inc.

Yair Alon

Mark H Jacobs

Mostafa A Karam

Fred W Erickson

Joseph H Geiger

Gregory Medlin

Kyle Bailey

Garth Ernest Weals

A technique for estimating the closest point of approach (CPA) of an object includes: tracking a range rate of the object based on Doppler measurements of the object; computing a first CPA estimate based on the tracked range rate; separately tracking a position of the object based on position measurements of the object; computing a second CPA estimate based on the tracked position; and computing a fused CPA estimate based on the first and second CPA estimates.

Technique for determining closest point of approach

A method for registering a radar system. The method includes obtaining first values for a location of a target relative to the radar system using radar system initiated signals, obtaining geo-referenced location data for and from the target, obtaining second values for the location of the target relative to the radar system using the geo-referenced location data, computing location registration bias errors for the radar system using the first and second values, and registering the radar system using the computed location registration bias errors.

Radar registration using targets of opportunity

A receiver in a mode 5 air traffic control system provides amplitude and phase signal outputs a digital data stream containing preamble and flight information from data transmitted from an aircraft. A signal splitter divides the amplitude and phase signal outputs between an odd channel and an even channel that carry odd-numbered pulses and even-numbered pulses, respectively. An odd channel data decoder connected to the signal splitter extracts signals encoded in the odd channel and forms an odd data stream and an even channel data decoder connected to the signal splitter extracts signals encoded in the even channel and forming an even data stream. A preamble correlator correlates the odd and even data streams with a predefined preamble mask to detect potential valid preambles, and preamble decision logic processes signals output from the preamble correlator to identify which of the preambles actually are actually valid.

Mode 5 detection process using phase and amplitude correlation

A method for mitigating multipath impacts on azimuth accuracy in a monopulse interrogator is accomplished by calculating samples of monopulse ratio for samples of antenna boresight angles based on data received from an interrogation of a target. Samples of traditional target azimuth from the samples of monopulse ratio are calculated. A mean of the samples of traditional target azimuth is calculated. An alternative target azimuth from the samples of monopulse ratio is calculated. Whether a multipath signal exists is determined from observing a standard deviation of the samples of traditional target azimuth, and using the mean of the traditional target azimuth if a multipath signal does not exist and using the alternative target azimuth if a multipath signal does exist.

Technique for mitigating multipath impacts on azimuth accuracy in a monopulse interrogator

In a radar system, a monopulse calibration table is constructed from live targets of opportunity. A center of gravity or weighted average of normalized signals &#x394;V received at SUM and DIFF channels from a live target are used to determine the target's actual azimuth. Off bore sight angles (OBA) of the target are then determined from the target's actual azimuth. Normalized received signal values of &#x394;V are converted to nearest-valued integers. The OBA s that correspond to each integer-valued normalized received signal are averaged and can then be plotted as a function of normalized received signal value &#x394;V. Different tables or plots can be constructed for elevation angles. An equation of a best-fit line the matches or at least closely approximates the plotted data is determined to smooth the actual data.

Using radar targets of opportunity to build a monopulse calibration table

An exemplary radar system includes a waveform generator that generates a control waveform. An in-phase and quadrature modulator receives the control waveform from the waveform generator and in turn generates a waveform output that is amplified by a power amplifier before being transmitted from an antenna.

Radar based application programmable waveform generator component

A method for eliminating signals from false targets in a secondary surveillance radar system includes the steps of obtaining plots of radar data for the same target. The range from the radar system to the targets is determined, and the target plot having smallest range of all target plots that indicate reflection of radar signals from the same target is accepted as being a real target. Other target data is rejected as being from a radar reflector. The coordinates of radar reflectors may be stored in a database to form a map of reflectors in the vicinity of the radar.

False reflected target elimination and automatic reflector mapping in secondary surveillance radar

The invention is a method for radar registration by determining initially unknown azimuth and range biases (errors) in a system of multiple, overlapping coverage radars. Track data from multiple radar systems corresponding to a common target are associated into track pairs. Track pair data is then used to calculate state vectors in a multi-dimensional vector space (preferably six-dimensional), with state vector components corresponding to both position and velocity information. From these state vectors an average normalized statistical distance is calculated, where the averaging is over multiple track pairs. An azimuthal bias parameter (and preferably also a range bias parameter) are then varied to minimize the average normalized statistical distance, thereby finding the best estimates of the corrections required to register the multiple radars.

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Thousand Oaks, CA, United States of America

Yair Alon