Clutter Elimination Patents (Class 342/159)
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Patent number: 6847324Abstract: Systems and methods for automated detection and removal of solar interference in real time from NEXRAD or other similar radar products. The radar site latitude and longitude and scan elevation time are extracted from the radar data and a position of the Sun is determined for the extracted latitude and longitude and scan time. A radial that has been contaminated with solar interference is determined and the solar interference is removed from that radial; The removal process does not impact the timeliness of critical products, and conservatively removes solar interference. In addition inaccuracies with NEXRAD clock time synchronization are accounted for to ensure accurate results.Type: GrantFiled: September 29, 2003Date of Patent: January 25, 2005Assignee: WSI CorporationInventors: Steven John Honey, Dennis Andrew Lang
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Patent number: 6847921Abstract: The invention is a method for analyzing spatially-varying noise in seismic data. Transitions between data values at adjacent data locations in a seismic data set are represented by Markov chains. Transition probability matrices are constructed from the Markov chains. Data values are predicted from the calculated transition probabilities. Noise values are determined from the predicted data values.Type: GrantFiled: April 7, 2003Date of Patent: January 25, 2005Assignee: ExxonMobil Upstream Research CompanyInventors: Alex Woronow, John F. Schuette, Chrysanthe S. Munn
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Publication number: 20040257270Abstract: The invention concerns a passive radar receiver with an array of antennas for a OFDM received signal comprising frames of symbols each emitted on coded orthogonal carriers. After formatting received signals into digital symbols, dummy signals from dummy OFDM emitters at different distances from and in different directions relative to the receiver are generated and added to the signals picked up by the antennas. The modified received signals are filtered by means of inverse covariance matrices in order to eliminate at least unwanted zero Doppler effect signals and to provide an isotropic reception diagram without blind sector of direct path being generated and by detecting mobile targets along the direct path.Type: ApplicationFiled: August 26, 2003Publication date: December 23, 2004Inventor: Dominique Poullin
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Patent number: 6833808Abstract: A method and apparatus for processing of a signal in which a variation in phase between a transmitted and reflected pulse is modeled, as is the amplitude of the pulse. The modeled phase and amplitude are used to smooth the data by reducing phase noise present on the signal thereby enhancing the signal to noise ratio.Type: GrantFiled: February 5, 2003Date of Patent: December 21, 2004Assignee: QinetiQ LimitedInventors: Huw D Rees, William N Dawber
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Patent number: 6831592Abstract: An HF radar system comprises a transmitting system, a receiving system, a signal processing system and a frequency management/ionospheric sounding system. The transmitting system comprises a transmitting antenna array configured to transmit a beam in a near vertical direction and a transmitting device arranged to drive the transmitting antenna array at frequencies suitable for downward refraction by the ionosphere. The receiving system comprises a receiving antenna array configured to receive returning signals from a target area returning to the receiving antenna array via refraction at the ionosphere. The signal processing system comprises a digital data processing system. The frequency management/sounding system comprises cooperating transmitting and receiving systems sending HF signals to the ionosphere and analysing the returning signals. Alternatively, the system may have a duplexed antenna array.Type: GrantFiled: January 7, 2003Date of Patent: December 14, 2004Assignee: Alenia Marconi Systems LimitedInventor: Kenneth H Perry
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Publication number: 20040239554Abstract: In order to create a method for eliminating dummy objects in short-range pulse radar sensors, in which radar pulses are transmitted at a defined frequency, and the time until they are reflected by an object and received again is measured, and besides the transmitted pulse (TX pulse), a delayed second pulse (RX pulse) is generated, which avoids the known disadvantages of the prior art and with which the elimination of dummy objects in short-range pulse radar sensors can be assured, it is provided that the transmitted pulses (TX pulses) and the additionally generated second pulses (RX pulses) delayed relative to them are modulated by a binary phase-shift keying process.Type: ApplicationFiled: March 8, 2004Publication date: December 2, 2004Inventors: Matthias Eckel, Juergen Hoetzel
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Patent number: 6822606Abstract: This invention relates to a spectral generator and a spectral generation method for receiving pre-processed range-doppler-sensor data and generating at least one noise-reduced high-resolution spectrum therefrom. The spectral generator comprises a window generator that generates a window which defines a plurality of range-doppler cells. The spectral generator further comprises a covariance matrix calculator that is in communication with the window generator to receive the range-doppler-sensor data within the window and calculate a covariance matrix estimate for a range-doppler cell of interest in the window. The spectral generator also includes a spectral calculator that is in communication with the covariance matrix calculator to calculate a high-resolution spectral vector based on a location matrix and a noise subspace matrix estimate.Type: GrantFiled: March 7, 2003Date of Patent: November 23, 2004Assignee: Raytheon Canada LimitedInventors: Tony Ponsford, Reza Dizaji
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Patent number: 6816109Abstract: A method for automatic association of moving target indications from at least one entity traveling along a route. A moving target indicator radar is used to detect a plurality of moving target indication data. The moving target indication data proximate to the identified route is selected and presented in a distance-time graph, such that each selected moving target indication data has a unique distance along route and a unique observation-time value. The selected moving target indication data are then transformed from the distance-time coordinate to a slope-intercept coordinate, such that co-linear moving target indication data in the distance-time coordinate are transformed into a plurality of points superposed together with nearly identical slope values and nearly identical distance intercept value. The superposed points are mapped back to the distance-time coordinate, and the moving target indication data corresponding to the superposed points are thus associated.Type: GrantFiled: August 4, 2003Date of Patent: November 9, 2004Assignee: Northrop Grumman CorporationInventor: Steven A. Schwartz
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Patent number: 6812886Abstract: Described herein are frequency-domain back-projection processes for forming spotlight synthetic aperture radar (“SAR”) images that are not corrupted by the effects of multiple-bounce ghosting artifacts. These processes give an approximately exact reconstruction of the multiple bounce reflectivity function (MBRF) ƒ(x,y,&ggr;). Specifically, the evaluation of ƒ(x,y,&ggr;) in the &ggr;=0 plane gives an approximately exact reconstruction of the true object scattering centers which is uncorrupted by multiple-bounce contributions to the phase history data G(&xgr;, &thgr;). In addition, the non-zero dependence of ƒ(x,y,&ggr;) upon the MB coordinate &ggr; can be used to facilitate the identification of features-interest within the imaged region.Type: GrantFiled: August 1, 2003Date of Patent: November 2, 2004Assignee: Science Applications International CorporationInventor: David Alan Garren
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Patent number: 6809681Abstract: An uncorrelated clutter noise cancellation method and apparatus employing a measured ambiguity function sample for each randomly-modulated transmission pulse in a randomly-modulated pulsed Doppler radar system. The ambiguity function samples are calculated from a stored copy of the randomly-modulated transmission signal. Estimates of the uncorrelated clutter backscatter are first developed by calculating the amplitude and phase of the radar returns detected in target range and velocity cells corresponding to stationary scatterers. The stationary scatterer contribution to each target cell, computed according to the sample ambiguity function, is then subtracted to eliminate the uncorrelated noise component in the return signal for the target cell. This clutter cancellation technique does not rely on correlations between the randomly-modulated transmission signal and the clutter return signal.Type: GrantFiled: August 25, 1992Date of Patent: October 26, 2004Assignee: Raytheon CompanyInventor: Alexander Niechayev
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Patent number: 6809682Abstract: A method for discriminating and tracking a target in a clutter cloud includes transmitting a radar signal at a signal bandwidth to: identify a range extent of a clutter cloud; determine a centroid and a velocity growth rate of the clutter cloud; and identify a direction of movement of the centroid of the clutter cloud. The method may also include locking a another radar signal having a greater signal bandwidth onto the centroid of the clutter cloud whereby the centroid is tracked within one radar range resolution bin; providing a delay line that includes at least two Doppler filters and is configured to cover a Doppler frequency range corresponding to a velocity growth rate of the clutter cloud; and processing a reflected radar signal corresponding to the greater signal bandwidth. The processing of the reflected radar signal may comprise passing the reflected radar signal through the delay line to mitigate a portion of the reflected signal that is reflected by the clutter cloud.Type: GrantFiled: January 16, 2003Date of Patent: October 26, 2004Assignee: The United States of America as represented by the Secretary of the ArmyInventor: J. Michael Madewell
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Publication number: 20040201517Abstract: A radar detector (10) includes a first period detector (76, 122), a second period detector (96, 120) and a third period detector (86, 124) within a multi-period periodicity validator 38. The first period detector (76, 122) detects radar pulses exhibiting one-half of an expected pulse period (48), the second period detector (96, 120) detects radar pulses exhibiting the expected pulse period (48), and the third period detector (86, 124) detects radar pulses exhibiting twice the expected pulse period (48). A plurality of pulse-train records (40) can simultaneously track a plurality of possible pulse trains. A control element (84, 136, 138) accounts for missing pulses and corrects the expected pulse period when missing pulses have caused the expected pulse period to be inaccurate.Type: ApplicationFiled: March 24, 2004Publication date: October 14, 2004Applicant: GlobespanVirata, Inc.Inventor: Daniel Davidson MacFarlane Shearer
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Patent number: 6803876Abstract: This invention relates to radar signal processing. In particular, this invention concerns Doppler processing and clutter filtering on irregular Pulse Repetition Time (PRT) sampled signal. This invention solves the above-mentioned drawbacks, in particular solving the velocity ambiguity and filtering any type of clutter, providing a deconvolution method which filter any kind of clutter even varying clutter like sea clutter, rain clutter . . .Type: GrantFiled: June 4, 2003Date of Patent: October 12, 2004Assignee: Thales Nederland B.V.Inventor: Radmila Erkocevic-Pribic
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Patent number: 6798375Abstract: A radar device includes elements for generating a carrier signal having a carrier frequency fT, elements for generating pulses with a pulse repetition frequency fPW, elements for distributing the carrier signal to a transmission branch and a receiving branch, elements for modulate the carrier signal in the transmission path using the undelayed pulses, elements for modulating the carrier signal in the receiving branch using the delayed pulses and for generating a reference signal, elements for mixing the reference signal in the receiving branch with a received signal and elements for integrating the mixed signal. Elements are provided for binary phase shift keying (BPSK) modulation of the carrier signal and elements are provided for switching the polarity of the received signal. A method for suppressing interference in a radar device is also described.Type: GrantFiled: December 18, 2002Date of Patent: September 28, 2004Assignee: Robert Bosch GmbHInventor: Thomas Brosche
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Publication number: 20040183713Abstract: A vehicle radar system extracts peak frequencies fbu and fbd of respective beat signals B1 to B9 representing the frequency difference between a transmission signal fs and a plurality of received signals fr1 to fr9. The phase difference of respective beat signals B1 to B9 at the peak frequencies fbu and fbd is converted into a frequency signal. In the case of reflection from a close range road surface or raindrops, the phase difference of each beat signal is irregular. The peak frequency intensity of a converted frequency signal is small. This system compares the peak frequency intensity of the converted frequency signal with predetermined criterion intensity. Then, the system identifies an objective with a close range road surface or raindrops when the peak frequency intensity of the converted frequency signal is not larger than the predetermined criterion intensity.Type: ApplicationFiled: January 27, 2004Publication date: September 23, 2004Applicant: DENSO CORPORATIONInventors: Hiroaki Kumon, Yukimasa Tamatsu
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Publication number: 20040178951Abstract: This invention relates to a spectral generator and a spectral generation method for receiving pre-processed range-doppler-sensor data and generating at least one noise-reduced high-resolution spectrum therefrom. The spectral generator comprises a window generator that generates a window which defines a plurality of range-doppler cells. The spectral generator further comprises a covariance matrix calculator that is in communication with the window generator to receive the range-doppler-sensor data within the window and calculate a covariance matrix estimate for a range-doppler cell of interest in the window. The spectral generator also includes a spectral calculator that is in communication with the covariance matrix calculator to calculate a high-resolution spectral vector based on a location matrix and a noise subspace matrix estimate.Type: ApplicationFiled: March 7, 2003Publication date: September 16, 2004Inventors: Tony Ponsford, Reza Dizaji
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Publication number: 20040178944Abstract: An RFID system using encoded digital information utilizing pulsed linear frequency modulation (LFM). The LFM waveform is sent from an24 aircraft or satellite and is received by a transponder. The LFM waveform is demodulated using both, an AM and an FM receiver. The demodulated data is compared to preprogrammed criteria tables, and after validation is decoded and utilized. Algorithms in the transponder are used to determine the frequency deviation and for calculating the direction of the slope of the LFM input signal. The valid RF signal is stored in a delay element, encoded with the transponder data using phase modulation (PM), and frequency modulation (FM). The tag transmission is synchronized to the input LFM waveform. The transmit/receive chopping signal prevents unwanted oscillations and is capable of randomization.Type: ApplicationFiled: March 12, 2001Publication date: September 16, 2004Inventors: David L. Richardson, Andrzej Sobski, Kenneth D. Gorham, Scott A. Stratmoen
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Patent number: 6791489Abstract: An RFID system using encoded digital information utilizing pulsed linear frequency modulation (LFM). The LFM waveform is sent from an aircraft or satellite and is received by a transponder. The LFM waveform is demodulated using both, an AM and an FM receiver. The demodulated data is compared to preprogrammed criteria tables, and after validation is decoded and utilized. Algorithms in the transponder are used to determine the frequency deviation and for calculating the direction of the slope of the LFM input signal. The valid RF signal is stored in a delay element, encoded with the transponder data using phase modulation (PM), and frequency modulation (FM). The tag transmission is synchronized to the input LFM waveform. The transmit/receive chopping signal prevents unwanted oscillations and is capable of randomization.Type: GrantFiled: March 12, 2001Date of Patent: September 14, 2004Assignee: Northrop Grumman CorporationInventors: David L. Richardson, Andrzej Sobski, Kenneth D. Gorham, Scott A. Stratmoen
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Patent number: 6791491Abstract: The invention relates to a method for attenuating interference in a positioning receiver of an electronic device, in which method a signal transmitted by satellites of a positioning system is received through a second antenna. The electronic device further comprises at least a mobile station and a first antenna to be used at least as a transmission antenna of the mobile station. In the method the strength of at least one interference signal generated in the electronic device is determined, a compensation signal corresponding to the strength of the determined interference signal is produced, and said compensation signal is combined to a signal received through a second antenna. The combined signal is directed to the positioning receiver.Type: GrantFiled: April 23, 2002Date of Patent: September 14, 2004Assignee: Nokia CorporationInventor: Olli Talvitie
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Publication number: 20040150555Abstract: A radar system that utilizes predetermined, pseudorandom, or random waveforms that may be substantially matched to the impulse response of the radar and any surrounding clutter such that the signal-to-clutter ratio may be optimized and/or such that specific targets may be identified and/or classified.Type: ApplicationFiled: January 31, 2003Publication date: August 5, 2004Applicant: The Ohio State UniversityInventor: Eric K. Walton
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Patent number: 6771207Abstract: Radar coverage maps having blockage, coverage and clutter features available for ease of interpretation are provided using terrain data to establish such features in data sets. The data sets provide a basis for the modified display. Multiple tilts of the radar scan may be represented. Multiple radar zones may be overlapped to provide a mosaic of a region showing areas of no coverage despite overlap.Type: GrantFiled: June 25, 2003Date of Patent: August 3, 2004Assignee: Unisys CorporationInventor: Joseph C. Lang
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Patent number: 6765525Abstract: A method for reducing the false alarm rate, i.e. the number of alarms of fixed targets erroneously declared as moving targets in the radar images of two- or multi-channel MTI radar devices, wherein the suppression of fixed target echoes over the moving target echoes within the main antenna lobe occurs through a space time adaptive processing—STAP—filter. The method uses a comparison of the amplitude amounts or power values of the range Doppler frequency cells with a threshold that can be specified in constant terms and summary of the resulting alarms. A target function is compared with defined test functions and selection criteria are determined from suitable combined calculation methods that are applied to the test and target functions for the purpose of classifying a respective target alarm as a moving or fixed target alarm.Type: GrantFiled: February 21, 2003Date of Patent: July 20, 2004Assignee: Eads Deutschland GmbHInventors: Bernhard Bickert, Jochen Meyer-Hilberg
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Patent number: 6750804Abstract: A system and method for detecting a target. The inventive method includes the steps of receiving a complex return signal of an electromagnetic pulse having a real and an imaginary component; extracting from the imaginary component information representative of the phase component of the return signal; and utilizing the phase component to detect the target. Specifically, the phase components are those found from the complex range-Doppler map. More specific embodiments further include the steps of determining a power spectral density of the phase component of the return signal; performing a cross-correlation of power spectral density of the phase component of the return signal between different antenna-subarray (quadrant channels); and averaging the cross-correlated power spectral density of the low frequency components. In an alternative embodiment, the cross-correlation is performed on the phase component of the range-Doppler map directly.Type: GrantFiled: April 4, 2002Date of Patent: June 15, 2004Assignee: Raytheon CompanyInventors: Hai-Wai Chen, Harry A. Schmitt, George T. David, Dennis C. Braunreiter, Alphonso A. Samuel
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Patent number: 6747593Abstract: A system and method for controlling clutter Doppler spread in a bistatic radar system is developed resulting in enhanced detection of low-Doppler targets or improved SAR mode performance. In an illustrative embodiment, a bistatic radar system (10) includes a transmitter (12) for transmitting electromagnetic energy (106) towards a target (16), a receiver (14) adapted to receive the electromagnetic energy (116) reflected from the target (16), and a processor (122) for optimizing a parameter or parameters of the system such that the directional derivative of the bistatic Doppler field along the isorange contour is near a desired value. The parameters to be optimized may include the transmitter velocity vector, the receiver velocity vector, or the receiver azimuth flight direction. The desired value is the minimal absolute value of the directional derivative in order to minimize the clutter Doppler spread, or the maximum absolute value of the directional derivative in order to maximize the clutter Doppler spread.Type: GrantFiled: June 26, 2003Date of Patent: June 8, 2004Assignee: Raytheon CompanyInventor: Amin G. Jaffer
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Publication number: 20040095269Abstract: To provide a radar system mounted on a vehicle that reliably detects the reception of the interference wave with high-performance and inexpensively. There is provided a radar system mounted on a vehicle for detecting a target object, including a transmitter for transmitting an electromagnetic wave, a receiver for receiving the electromagnetic wave reflected by the target object, a signal processor for measuring a distance between a vehicle of his/her own and the target object and a relative velocity on the basis of the transmitting electromagnetic wave and the receiving electromagnetic wave, and an interference detector for suspending a transmit operation of the transmitter under a control of the signal processor to detect an interference signal from another external device.Type: ApplicationFiled: November 4, 2003Publication date: May 20, 2004Applicant: MITSUBISHI DENKI KABUSHIKI KAISHAInventors: Naohisa Uehara, Koichi Kai
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Publication number: 20040090361Abstract: A radar device is described having means (10) for generating a carrier signal having a carrier frequency fT, means (12, 13, 15, 17) for generating pulses having a pulse repetition rate fPW, means (16) for splitting the carrier signal between a transmission branch and a reception branch, means (18, 19, 21, 27, 29) for delaying the pulses, means (24) for mixing the carrier signal in the reception branch with a reception signal and means (26) for integrating the mixed signal, whereby means (20, 23) for modulating the carrier signal in the transmission branch with the delayed pulses are provided and means for altering the delay in the pulses according to a predetermined code are provided. A method of suppressing interference with the functioning of a radar device is also described.Type: ApplicationFiled: December 16, 2003Publication date: May 13, 2004Inventor: Thomas Brosche
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Patent number: 6731233Abstract: In a method of suppressing jammer signals in the received signal of radar antennas of HPRF applications (such as pulse Doppler radar systems) by means of Fast Fourier Transformation and side lobe cancellation, the receiving radar antenna has a sum channel, a difference channel and an auxiliary channel. The received signal is first transformed in the sum, difference and auxiliary channels from the time domain into the frequency domain using a Fast Fourier Transformation (FFT). Subsequently, the the jammer signal, particularly the side lobe jammer, is suppressed in the frequency domain by means of side lobe cancellation.Type: GrantFiled: August 16, 2002Date of Patent: May 4, 2004Assignee: EADS Deutschland GmbHInventors: Franz-Xaver Hofele, Dieter Nagel, Klaus-Peter Schmitt, Markus Rothmaier
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Publication number: 20040066323Abstract: In a pulse-radar method, in particular for motor vehicles, different time slots (21, . . . , 24) of a time frame (20) are predefined. During one time slot, a radar sensor (1) emits at least one radar pulse and receives the echo signal(s). During the remaining time slots (22, 23, 24) the radar sensor (1) monitors whether interference signals occur. On the basis of the interference signals occurring per time slot (21, . . . , 24), a decision is made whether the radar sensor (1) should continue its transmitting and receiving operation in the predefined time slot (21) or should switch to one of the remaining time slots (22, 23, 24) of the time frame (20). The method is suited for the concurrent operation of a plurality of radar sensors, without this causing interference.Type: ApplicationFiled: November 5, 2003Publication date: April 8, 2004Inventor: Karl-Heinz Richter
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Publication number: 20040066331Abstract: The invention concerns a passive radar receiver for a received orthogonal frequency division multiplex-type signal consisting of symbol frames each emitted on coded orthogonal carriers. After formatting the received signals into digital symbols (S1 S1), a filtering circuit (2) eliminates by subtraction or using a covariance matrix, in the symbol signal at least unwanted signals with null Doppler effect so as to apply a filtered signal (X′) including essentially signals backscattered by mobile targets to a Doppler-distance correlator (4).Type: ApplicationFiled: July 30, 2003Publication date: April 8, 2004Inventor: Dominique Poullin
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Patent number: 6717545Abstract: This invention relates to an adaptive detection system and method for analyzing range-doppler-azimuth data for target detection. The detection system has a threshold calculator for calculating a threshold value that is based on the standard deviation of the range-doppler-azimuth data and a predetermined probability of detection. The detection system also has a detection module in communication with the threshold calculator to receive the threshold value. The detection module calculates an estimated target amplitude and an estimated noise floor amplitude based on the range-doppler data that is located in a detection window. The detection module detects a target when the difference between the estimated target amplitude and the estimated noise floor amplitude is larger than the threshold value.Type: GrantFiled: March 7, 2003Date of Patent: April 6, 2004Assignee: Raytheon Canada LimitedInventors: Reza Dizaji, Tony Ponsford
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Publication number: 20040056793Abstract: In an automotive radio wave radar, a center frequency of a transmitted wave is shifted at a certain cycle, and position information of an obstacle detected at three or more center frequencies is subjected to decision by majority to determine whether detection results of the obstacle are erroneous with the occurrence of jamming. If any of the detection results is determined to be abnormal, the abnormal result is discarded. An automotive radio wave radar is realized which can correctly perform the obstacle detection even in the event of jamming without causing erroneous obstacle detection or omission of the detection.Type: ApplicationFiled: September 22, 2003Publication date: March 25, 2004Applicant: HITACHI, LTD.Inventors: Shigeaki Matsubara, Kazuaki Takano, Hiroshi Kuroda
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Publication number: 20040056794Abstract: This invention relates to radar signal processing. In particular, this invention concerns Doppler processing and clutter filtering on irregular Pulse Repetition Time (PRT) sampled signal.Type: ApplicationFiled: June 4, 2003Publication date: March 25, 2004Inventor: Radmila Erkocevic-Pribic
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Publication number: 20040051658Abstract: In a method of suppressing jammer signals in the received signal of radar antennas of HPRF applications (such as pulse Doppler radar systems) by means of Fast Fourier Transformation and side lobe cancellation, the receiving radar antenna has a sum channel, a difference channel and an auxiliary channel. The received signal is first transformed in the sum, difference and auxiliary channels from the time domain into the frequency domain using a Fast Fourier Transoformation (FFT). Subsequently, the the jammer signal, particularly the side lobe jammer, is suppressed in the frequency domain by means of side lobe cancellation.Type: ApplicationFiled: August 16, 2002Publication date: March 18, 2004Inventors: Franz-Xaver Hofele, Dieter Nagel, Klaus-Peter Schmitt, Markus Rothmaier
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Patent number: 6707415Abstract: A method, system, and computer program product for storing weather radar return data into a three-dimensional buffer. The system includes a radar system that transmits a radar signal and generates a radar measurement as a result of radar return of the transmitted radar signal. A three-dimensional buffer includes a plurality of storage locations. A processor is coupled to the radar system and the buffer. The processor generates or updates a reflectivity value in storage locations in the three-dimensional buffer based on the generated radar measurement, a previously stored reflectivity value for the storage location, and at least one of an uncertainty value for the storage location. The generated reflectivity value is stored in the three-dimensional buffer according to the storage location.Type: GrantFiled: December 20, 2002Date of Patent: March 16, 2004Assignee: Honeywell International Inc.Inventor: Paul E. Christianson
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Publication number: 20040046689Abstract: A method and apparatus for processing of a signal in which a variation in phase between a transmitted and reflected pulse is modelled, as is the amplitude of the pulse. The modelled phase and amplitude are used to smooth the data by reducing phase noise present on the signal thereby enhancing the signal to noise ratio.Type: ApplicationFiled: February 5, 2003Publication date: March 11, 2004Inventors: Huw D Rees, William N Dawber
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Publication number: 20040041725Abstract: A radar signal processing unit comprises a Fourier transform section 1 for executing Fourier transform of the received signal to a frequency signal, a frequency domain power calculation section 2 for calculating a power spectrum of electric power for each frequency from the frequency signal, an abnormal echo removal section 3 for determining the abnormal echo based on the power value of the power spectrum and outputting only the power spectrum not corresponding to the abnormal echo, an incoherent processing section 4 for performing incoherent integration of only the power spectrum not corresponding to the abnormal echo and averaging, and a signal detection section 5 for calculating the physical quantity of the atmosphere from the incoherent-integrated power spectrum.Type: ApplicationFiled: March 26, 2003Publication date: March 4, 2004Applicant: MITSUBISHI DENKI KABUSHIKI KAISHAInventors: Tomoya Matsuda, Toshio Wakayama
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Patent number: 6697013Abstract: A system for detecting and avoiding interference with radar signals in wireless network devices is described. The receiver circuit of the device receives incoming 5 GHz traffic. Such traffic could comprise both WLAN traffic as well as radar signals from radar systems. The incoming packets are treated as an input event, and are screened to be examined as radar pulses. Radar pulses are identified using the length of the detected event. The radar pulses are examined using frequency domain analysis, and the packet train is examined to find gaps between radar pulses. The periodic nature of the packet is determined using frequency domain and time domain analysis to calculate the period of the pulse train. Particular intervals within the pulse train are analyzed using threshold numbers of periodic pulses within the interval and threshold power levels for the pulses. The calculated period information is used to identify the radar source and screen non-radar traffic.Type: GrantFiled: December 31, 2001Date of Patent: February 24, 2004Assignee: Atheros Communications, Inc.Inventors: William McFarland, Chaohuang Zeng, Deepak Dhamdhere
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Patent number: 6697009Abstract: A system and method for detecting a radar target of interest in the presence of radar jamming interference include a sub-array beamformer, a sum and difference beamformer, a weight calculator, a composite beamformer, and a monopulse ratio calculator. A plurality of sub-arrays is formed from antenna array element data. Respective sum and difference beams are formed for each of the plurality of sub-arrays. A single weight is formulated from the sum and difference beams, respectively. Composite sum beams are formed in accordance with the sum weights and the sum beams, and composite difference beams are formed in accordance with the difference weights and the difference beams. Composite beams are formed such that at least one null of each of the composite beams is steered toward an interference and a boresight gain of each of the composite beams is maintained.Type: GrantFiled: July 3, 2002Date of Patent: February 24, 2004Assignee: Lockheed Martin CorporationInventor: Kai Bor Yu
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Patent number: 6691947Abstract: The present invention includes a system and method for accurately locating moving targets. The system includes a targeting aircraft that has a radar system with a simultaneous SAR radar/moving target mode that generates an image and identifies moving targets in the generated image. The targeting aircraft also includes a mapping component that matches the generated image to a stored digital map, and generates moving target location information based on the matched image and map and the identified moving targets.Type: GrantFiled: March 12, 2002Date of Patent: February 17, 2004Assignee: The Boeing CompanyInventor: Christopher M. La Fata
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Publication number: 20040027270Abstract: A system and method for highly selective intrusion detection using a sparse array of time modulated ultra wideband (TM-UWB) radars. Two or more TM-UWB radars are arranged in a sparse array around the perimeter of a building. Each TM-UWB radar transmits ultra wideband pulses that illuminate the building and the surrounding area. Signal return data is processed to determine, among other things, whether an alarm condition has been triggered. High resolution radar images are formed that give an accurate picture of the inside of the building and the surrounding area. This image is used to detect motion in a highly selective manner and to track moving objects within the building and the surrounding area. Motion can be distinguished based on criteria appropriate to the environment in which the intrusion detection system operates.Type: ApplicationFiled: June 2, 2003Publication date: February 12, 2004Inventors: Larry W. Fullerton, James L. Richards
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Patent number: 6690317Abstract: The present invention comprises a system, method, and computer program product for suppressing terrain returns in weather radar images. A weather radar display system includes a memory, a terrain database, a display, and a display processor coupled to the memory, terrain database, and the display. The display processor includes a first component configured to extract radar return data stored in the memory based on aircraft position, a second component configured to extract data stored in the terrain database based on aircraft position, and a third component configured to selectively accept or discards or otherwise segregates data for display based upon the data extracted from memory and the data extracted from the terrain database.Type: GrantFiled: February 19, 2002Date of Patent: February 10, 2004Assignee: Honeywell International Inc.Inventors: Roland Y. Szeto, Bill G. Cornell
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Patent number: 6683559Abstract: An unwanted peak occurring due to an antenna sidelobe and an unwanted peak occurring due to a harmonic are eliminated in a radar apparatus. A peak from a target that can cause an unwanted peak is found based on the intensity of the peak, and a search is made for a peak having a predetermined positional relationship with the thus found peak. If such a peak is located, then it is determined whether the peak is a candidate for an unwanted peak, based on the difference between the intensity of the peak and the intensity of the main peak. If both of the paired peaks are determined as being candidates for unwanted peaks, it is determined that the peaks are unwanted peaks.Type: GrantFiled: November 22, 2002Date of Patent: January 27, 2004Assignee: Fujitsu Ten LimitedInventors: Sadanori Matsui, Hisateru Asanuma
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Patent number: 6677886Abstract: A method of determining the presence of a weather or other airborne (non-aircraft) clutter in a radar detection system is disclosed. The method includes feature calculations of a cluster of detections, and characterizing the cluster. Confidence factors are determined from the characterization of a cluster and a determination is made from the confidence factors whether the cluster represents a real aircraft or a false target.Type: GrantFiled: October 28, 2002Date of Patent: January 13, 2004Assignee: Raytheon CompanyInventor: Yuchoi Francis Lok
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Patent number: 6674397Abstract: A filter, includes a first order band pass filter configured to process non-zero amplitude gated radar return samples and process a portion of received zero amplitude return samples. The filter also calculates past filter outputs based on filter outputs generated during previous non-zero gated radar return samples.Type: GrantFiled: May 13, 2002Date of Patent: January 6, 2004Assignee: Honeywell International Inc.Inventors: James R. Hager, Lavell Jordan, Todd R. Burlet, Curtis J. Petrich
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Patent number: 6664916Abstract: A system containing a navigational marker, the navigational marker having the ability to reflect radar in such a manner that the navigational marker is identified. In one embodiment, a polarized radar-reflective material is affixed to the navigational marker. A radar signal is reflected by the polarized radar-reflective material, causing the reflected radar signal to be polarized. The reflected radar signal is received and the navigational marker is identified. The radar system contains a detector/decoder capable of distinguishing the type of navigational marker based on the reflected radar signal. The detector/decoder relays information about the navigational marker to a display. In another embodiment, a navigational marker contains a radio responder. When a radar signal illuminates the navigational marker, the radio responder transmits a signal containing encoded data. A receiver detects the signal from the responder and decodes the encoded data. The decoded data is relayed to a display.Type: GrantFiled: August 9, 2002Date of Patent: December 16, 2003Inventors: Todd R. Stafford, Dennis C. Higgins
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Patent number: 6661366Abstract: A radar system and technique provide the capability to detect a target of interest and maintain the detection in the presence of multiple mainlobe and sidelobe jamming interference. The system and technique utilize digital beamforming to form sub-arrays for canceling jamming interference. Jamming is adaptively suppressed in the sub-arrays prior to using conventional deterministic methods to form the sum, &Sgr;, and difference, &Dgr;, beams for monopulse processing. The system and technique provide the ability to detect a target of interest, provide an undistorted monopulse ratio, m, and maintain target angle estimation, in the presence of multiple mainlobe and multiple sidelobe jammers.Type: GrantFiled: June 15, 2001Date of Patent: December 9, 2003Assignee: Lockheed Martin CorporationInventor: Kai-Bor Yu
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Patent number: 6661367Abstract: A signal processor includes a unit for forming designated groups from radar reflection signals, a memory unit for storing the designated groups of radar reflection signals individually, a first calculator for calculating a standard background signal SB from each of the designated groups of radar reflection signals stored individually. The signal processor further includes a second calculator for calculating differential signals between the individual radar reflection signals and the standard background signal SB separately for each of the designated groups and a unit for identifying the signal reflected from a search object out of the differential signal.Type: GrantFiled: March 14, 2002Date of Patent: December 9, 2003Assignee: International Business Machines CorporationInventors: Kentaro Sugiyama, Atsushi Abe
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Patent number: 6661370Abstract: The invention detects a ghost occurring due to mispairing, reflections from a wall, or the like, and improves the ability of a radar to track targets when actual relative velocity changes by more than a certain value. If a stationary target is present within a prescribed region centered about a moving target, the stationary target is excluded from output data by determining it as being a target resulting from mispairing due to the detection of guardrail posts or similar structures. Further, a moving target that is expected to collide with an eligible target is also excluded from the output data by determining it as being a target resulting from mispairing due to the detection of a target having many reflecting points. For a moving target showing an unlikely relative velocity, pairing with some other peak is attempted by determining the moving target as being a target resulting from mispairing due to the detection of a plurality of moving targets moving in the same direction.Type: GrantFiled: December 9, 2002Date of Patent: December 9, 2003Assignee: Fujitsu Ten LimitedInventors: Masayuki Kishida, Sadanori Matsui, Yasuhiro Sekiguchi, Tokio Shinagawa, Daisaku Ono
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Publication number: 20030222813Abstract: The present invention is a system and method for detecting a jamming signal. The signal is detected by analyzing a spectrum of PCS, wireless network and pager wavebands (or, in other words, any wireless network) and by looking for unusual patterns. If unusual patterns are found, it is considered that a jammer is present. In a preferred embodiment of the invention, the system can be aboard a recovery vehicle, or be an integral part of an on-board unit on a vehicle.Type: ApplicationFiled: May 16, 2003Publication date: December 4, 2003Applicant: Boomerang Tracking Inc.Inventors: Andre Eric Boulay, Robert Nelson
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Publication number: 20030218565Abstract: An adaptive broadcast radar system for tracking targets is disclosed, the radar system includes a transmitter having sub-apertures and a receiver having sub-apertures. The transmitter sub-apertures generate and code a signal waveform. The signal waveform is coded with data about the transmitter, including the degrees of freedom. The receiver receives signals comprising direct path signals and scattered signals correlating to the signal waveforms from the transmitter. The receiver includes a signal processor that regenerates a transmit beam for the coded data, delay, and doppler information from the received signals. The signal processor generates data quads encapsulating the information.Type: ApplicationFiled: November 28, 2001Publication date: November 27, 2003Applicant: Lockheed Martin Mission SystemsInventor: Robert D. Budic