The removal of ground clutter from a Doppler shifted radar echo is examined from a non-traditional point of view that is particularly apt for an agile beam radar and digital signal processing. The observation in such a radar is, for each range sample, a finite duration sequence of complex envelope values. Thus, the observation is a complex vector. Clutter removal is the act of operating upon the observation vector to produce another vector that has its clutter component eliminated or substantially reduced. The operation is a matrix transformation that is, essentially, the inverse of the covariance matrix of the interference-noise plus clutter. The resulting vector is then applied to a bank of Doppler processes to produce: (a) test statistics for target detection; (b) spectral analysis to get the spectral moments of meteorological echo. The matrix processing approach removes the necessity for such things as initialization of the clutter filter. Spectral analysis is emphasized. The frequency response, clutter attenuation, and clutter improvement factor are defined in view of the matrix processing approach. In addition, the bias to be expected because of the clutter and its removal are analyzed and graphs are presented showing the bias to be expected for various spectral widths of clutter versus the frequency "notch" width of the matrix processor.
{"title":"A matrix clutter processor for agile beam radars","authors":"H. Urkowitz, H. Owen","doi":"10.1109/NRC.1998.677993","DOIUrl":"https://doi.org/10.1109/NRC.1998.677993","url":null,"abstract":"The removal of ground clutter from a Doppler shifted radar echo is examined from a non-traditional point of view that is particularly apt for an agile beam radar and digital signal processing. The observation in such a radar is, for each range sample, a finite duration sequence of complex envelope values. Thus, the observation is a complex vector. Clutter removal is the act of operating upon the observation vector to produce another vector that has its clutter component eliminated or substantially reduced. The operation is a matrix transformation that is, essentially, the inverse of the covariance matrix of the interference-noise plus clutter. The resulting vector is then applied to a bank of Doppler processes to produce: (a) test statistics for target detection; (b) spectral analysis to get the spectral moments of meteorological echo. The matrix processing approach removes the necessity for such things as initialization of the clutter filter. Spectral analysis is emphasized. The frequency response, clutter attenuation, and clutter improvement factor are defined in view of the matrix processing approach. In addition, the bias to be expected because of the clutter and its removal are analyzed and graphs are presented showing the bias to be expected for various spectral widths of clutter versus the frequency \"notch\" width of the matrix processor.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132777467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper derives the Neyman-Pearson discrete-time detector for phase/amplitude coded radar signals in the presence of spatially-white distributed Rayleigh clutter. We consider processing of data records which are long relative to the pulse duration. A measure of the optimum detector's performance gain over that of a standard correlator is derived and calculated for several waveforms of practical interest. It is also shown that for the clutter-limited case that the detection performance in spatially-distributed Rayleigh clutter is virtually independent of waveform coding. This last result allows one to use this detector with a non-coded pulse radar and achieve similar detection performance to that of a pulse coded radar when all other parameters are held constant provided as the clutter dominates the noise.
{"title":"Detection in distributed Rayleigh clutter","authors":"T. Foreman, S. G. Wilson","doi":"10.1109/NRC.1998.677999","DOIUrl":"https://doi.org/10.1109/NRC.1998.677999","url":null,"abstract":"This paper derives the Neyman-Pearson discrete-time detector for phase/amplitude coded radar signals in the presence of spatially-white distributed Rayleigh clutter. We consider processing of data records which are long relative to the pulse duration. A measure of the optimum detector's performance gain over that of a standard correlator is derived and calculated for several waveforms of practical interest. It is also shown that for the clutter-limited case that the detection performance in spatially-distributed Rayleigh clutter is virtually independent of waveform coding. This last result allows one to use this detector with a non-coded pulse radar and achieve similar detection performance to that of a pulse coded radar when all other parameters are held constant provided as the clutter dominates the noise.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124304431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is well known that detection of moving targets using an airborne radar is complicated by platform-induced spectral spreading of clutter returns. As a result, conventional pulse Doppler radars require a target to have a minimum detectable velocity (MDV) to be clear of mainbeam (and sidelobe) clutter. Extensive research into side-looking, multi-channel (i.e. multi-aperture) radars employing space-time adaptive processing (STAP) and displaced phase centre antenna (DPCA) processing techniques has been conducted, in order to reduce the requirement on MDV for airborne early warning (AEW) radar applications. GMTI (ground moving target indication) radars like JSTARS also employ similar techniques to detect slow ground moving targets such as tanks and jeeps. Most of the literature deals with side-looking airborne radars (SLAR), which is the case when the aperture phase centres lie along a line parallel to the flight path. This paper considers the design and performance of GMTI radars for the general, non-SLAR case, where the array is oriented away from the side, the extreme case being a forward-looking airborne radar (FLAR). A non-SLAR GMTI radar is attractive because it is applicable to mechanically rotated antenna arrays, often used for wide-angle surveillance; and, as a result, can be considered as an upgrade to existing surveillance radars.
{"title":"Airborne ground moving target indication using non-side-looking antennas","authors":"T. Nohara, P. Weber, A. Premji, T. Bhattacharya","doi":"10.1109/NRC.1998.678013","DOIUrl":"https://doi.org/10.1109/NRC.1998.678013","url":null,"abstract":"It is well known that detection of moving targets using an airborne radar is complicated by platform-induced spectral spreading of clutter returns. As a result, conventional pulse Doppler radars require a target to have a minimum detectable velocity (MDV) to be clear of mainbeam (and sidelobe) clutter. Extensive research into side-looking, multi-channel (i.e. multi-aperture) radars employing space-time adaptive processing (STAP) and displaced phase centre antenna (DPCA) processing techniques has been conducted, in order to reduce the requirement on MDV for airborne early warning (AEW) radar applications. GMTI (ground moving target indication) radars like JSTARS also employ similar techniques to detect slow ground moving targets such as tanks and jeeps. Most of the literature deals with side-looking airborne radars (SLAR), which is the case when the aperture phase centres lie along a line parallel to the flight path. This paper considers the design and performance of GMTI radars for the general, non-SLAR case, where the array is oriented away from the side, the extreme case being a forward-looking airborne radar (FLAR). A non-SLAR GMTI radar is attractive because it is applicable to mechanically rotated antenna arrays, often used for wide-angle surveillance; and, as a result, can be considered as an upgrade to existing surveillance radars.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114434320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Autofocus is critical for inverse synthetic aperture radar (ISAR) imaging. This paper develops two new approaches of autofocus for ISAR imaging based on beamforming. The ISAR observation model is established and the proposed approaches are described in detail. The relationships of the two approaches are identified and their statistical performance analysed. The results of processing simulated and real data confirm the validity of proposed approaches.
{"title":"Autofocus for inverse synthetic aperture radar (ISAR) imaging by beamforming","authors":"Z. She, R. Bogner, D. Gray","doi":"10.1109/NRC.1998.678006","DOIUrl":"https://doi.org/10.1109/NRC.1998.678006","url":null,"abstract":"Autofocus is critical for inverse synthetic aperture radar (ISAR) imaging. This paper develops two new approaches of autofocus for ISAR imaging based on beamforming. The ISAR observation model is established and the proposed approaches are described in detail. The relationships of the two approaches are identified and their statistical performance analysed. The results of processing simulated and real data confirm the validity of proposed approaches.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114995639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The present paper deals with the selection of the echoes received by modern airborne early warning radar (AEW) systems. It is shown that the proper selection of the radar echoes to be processed can give some useful guidelines for the reduction of the degrees of freedom (DOF) of the space-time processors. This is shown to be have the potentiality of a significant impact on the detection performance. Moreover, different data selection strategies imply different trade-offs between the number of spatial and temporal DOF to achieve the best detection performance.
{"title":"Data selection strategies for radar space time adaptive processing","authors":"P. Lombardo","doi":"10.1109/NRC.1998.678001","DOIUrl":"https://doi.org/10.1109/NRC.1998.678001","url":null,"abstract":"The present paper deals with the selection of the echoes received by modern airborne early warning radar (AEW) systems. It is shown that the proper selection of the radar echoes to be processed can give some useful guidelines for the reduction of the degrees of freedom (DOF) of the space-time processors. This is shown to be have the potentiality of a significant impact on the detection performance. Moreover, different data selection strategies imply different trade-offs between the number of spatial and temporal DOF to achieve the best detection performance.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122319434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A phased array antenna used in conjunction with a mechanically scanned or rotating radar can provide enhanced target tracking capability. The use of a single electronically-scanned aperture mounted on a rotating pedestal to obtain 360 degree coverage represents a cost-effective solution when compared with multiple-aperture approaches. The agile beam affords both flexibility and robustness with regard to radar resource management and multiple-target tracking capability. The key to realizing these benefits is the scheduling of additional electronic scans per revisit to achieve higher effective tracking rates than with conventional track-while-scan (TWS) operation. Frequency agility is employed to de-correlate the target echoes for the close temporal spacing of radar measurements which can occur. The paper describes the approach and derives performance bounds relative to uniform tracking-rate systems. Applications include air-traffic control radar as well as precision tracking and fire control systems.
{"title":"Phased array radar tracking with non-uniformly spaced measurements","authors":"T. W. Jeffrey","doi":"10.1109/NRC.1998.677975","DOIUrl":"https://doi.org/10.1109/NRC.1998.677975","url":null,"abstract":"A phased array antenna used in conjunction with a mechanically scanned or rotating radar can provide enhanced target tracking capability. The use of a single electronically-scanned aperture mounted on a rotating pedestal to obtain 360 degree coverage represents a cost-effective solution when compared with multiple-aperture approaches. The agile beam affords both flexibility and robustness with regard to radar resource management and multiple-target tracking capability. The key to realizing these benefits is the scheduling of additional electronic scans per revisit to achieve higher effective tracking rates than with conventional track-while-scan (TWS) operation. Frequency agility is employed to de-correlate the target echoes for the close temporal spacing of radar measurements which can occur. The paper describes the approach and derives performance bounds relative to uniform tracking-rate systems. Applications include air-traffic control radar as well as precision tracking and fire control systems.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127992509","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper investigates the model order selection problem for use with the multidimensional autoregressive (MAR) process in airborne radar detection processing which uses an innovations based detection algorithm (IBDA). Results indicate that a low order model should be used to accurately portray the return signal spectrum. Specifically, this paper investigates the use of the Akaike (1971) information criterion for model order selection. Examples are included for physically modeled data sets as well as actual radar data sets.
{"title":"Model order selection for multidimensional innovations based detection in airborne radar","authors":"J. Castro, J. LeBlanc","doi":"10.1109/NRC.1998.677991","DOIUrl":"https://doi.org/10.1109/NRC.1998.677991","url":null,"abstract":"This paper investigates the model order selection problem for use with the multidimensional autoregressive (MAR) process in airborne radar detection processing which uses an innovations based detection algorithm (IBDA). Results indicate that a low order model should be used to accurately portray the return signal spectrum. Specifically, this paper investigates the use of the Akaike (1971) information criterion for model order selection. Examples are included for physically modeled data sets as well as actual radar data sets.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"128 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133105668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present airborne experimental observations at UHF and VHF of electromagnetic scattering from terrain and demonstrate how such a signal can be used to determine target height. We describe the time difference of arrival (TDOA) processing and then go on to discuss how Doppler information can be used to supplement or replace TDOA processing. We describe two such methods. The first entails observing the Doppler separation between the target and its image and inverting to recover height. The second method uses the Doppler domain to filter out-of-plane energy and improve the performance of TDOA processing.
{"title":"Experimental observation and modeling of overland height finding","authors":"L. Zurk, B. Geddes","doi":"10.1109/NRC.1998.678037","DOIUrl":"https://doi.org/10.1109/NRC.1998.678037","url":null,"abstract":"We present airborne experimental observations at UHF and VHF of electromagnetic scattering from terrain and demonstrate how such a signal can be used to determine target height. We describe the time difference of arrival (TDOA) processing and then go on to discuss how Doppler information can be used to supplement or replace TDOA processing. We describe two such methods. The first entails observing the Doppler separation between the target and its image and inverting to recover height. The second method uses the Doppler domain to filter out-of-plane energy and improve the performance of TDOA processing.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129270180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents several techniques for mitigating the effects of an inclined linear array on STAP algorithms. A new technique, termed Doppler Warping is shown to completely mitigate the effects of the array inclination on the STAP algorithm by shifting the Doppler filters to track the Doppler frequency variation of clutter over range. After establishing the effects of array inclination on STAP algorithms, several techniques are presented to reduce the array inclination effects. Doppler Warping is shown to be computationally very inexpensive and to completely mitigate the effects of array inclination. Covariance analysis results are presented.
{"title":"Mitigating effects on STAP processing caused by an inclined array","authors":"G.K. Borsari","doi":"10.1109/NRC.1998.677990","DOIUrl":"https://doi.org/10.1109/NRC.1998.677990","url":null,"abstract":"This paper presents several techniques for mitigating the effects of an inclined linear array on STAP algorithms. A new technique, termed Doppler Warping is shown to completely mitigate the effects of the array inclination on the STAP algorithm by shifting the Doppler filters to track the Doppler frequency variation of clutter over range. After establishing the effects of array inclination on STAP algorithms, several techniques are presented to reduce the array inclination effects. Doppler Warping is shown to be computationally very inexpensive and to completely mitigate the effects of array inclination. Covariance analysis results are presented.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129467052","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One aspect of naval defence involves surveillance of the airspace in the vicinity of one's vessel. Both high-altitude and low-altitude missiles must be detected, tracked and targeted. A multi-function radar (MFR) that uses an electrically steerable pencil beam (phased array) to search the volume around the ship can provide the required capability. Monopulse sum and difference beams (azimuth and elevation) are provided to yield high resolution direction of arrival (DOA) estimates for detected targets, improving ship defence capabilities against modern threats. This paper is concerned with robust estimation of low-altitude targets such as sea skimming missiles for the challenging case where horizon-based jammers are present in the antenna's mainbeam. By exploiting the properties of the monopulse beams, spatially adaptive algorithms are developed that provide simultaneous mainbeam nulling and high-resolution target DOA estimation. Simulation results demonstrate the detection and estimation performance achievable. DOA estimates using suitably derived MUSIC (multiple signal classification), ML (maximum likelihood) and corrected adaptive monopulse (CAM) algorithms are compared.
{"title":"Adaptive mainbeam jamming suppression for multi-function radars","authors":"T. Nohara, P. Weber, A. Premji","doi":"10.1109/NRC.1998.678002","DOIUrl":"https://doi.org/10.1109/NRC.1998.678002","url":null,"abstract":"One aspect of naval defence involves surveillance of the airspace in the vicinity of one's vessel. Both high-altitude and low-altitude missiles must be detected, tracked and targeted. A multi-function radar (MFR) that uses an electrically steerable pencil beam (phased array) to search the volume around the ship can provide the required capability. Monopulse sum and difference beams (azimuth and elevation) are provided to yield high resolution direction of arrival (DOA) estimates for detected targets, improving ship defence capabilities against modern threats. This paper is concerned with robust estimation of low-altitude targets such as sea skimming missiles for the challenging case where horizon-based jammers are present in the antenna's mainbeam. By exploiting the properties of the monopulse beams, spatially adaptive algorithms are developed that provide simultaneous mainbeam nulling and high-resolution target DOA estimation. Simulation results demonstrate the detection and estimation performance achievable. DOA estimates using suitably derived MUSIC (multiple signal classification), ML (maximum likelihood) and corrected adaptive monopulse (CAM) algorithms are compared.","PeriodicalId":432418,"journal":{"name":"Proceedings of the 1998 IEEE Radar Conference, RADARCON'98. Challenges in Radar Systems and Solutions (Cat. No.98CH36197)","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1998-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130984507","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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