Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851848
S. Berger, B. Welsh
Recently, we proposed a dual channel matched filtering system as a replacement for a single channel matched filtering system that requires a transformation that block diagonalizes the correlation matrix. In this paper, we analyze a suboptimal dual channel system that uses a non-block diagonalizing transformation. We provide a lower bound for the efficiency of the suboptimal dual channel system relative to the optimal system. We also propose a criterion for selecting the non-block diagonalizing transformation that appears to provide a reliable indication of the average efficiency.
{"title":"Dual channel matched filter performance bound","authors":"S. Berger, B. Welsh","doi":"10.1109/RADAR.2000.851848","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851848","url":null,"abstract":"Recently, we proposed a dual channel matched filtering system as a replacement for a single channel matched filtering system that requires a transformation that block diagonalizes the correlation matrix. In this paper, we analyze a suboptimal dual channel system that uses a non-block diagonalizing transformation. We provide a lower bound for the efficiency of the suboptimal dual channel system relative to the optimal system. We also propose a criterion for selecting the non-block diagonalizing transformation that appears to provide a reliable indication of the average efficiency.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127891925","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}
Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851837
D. Arnaud, C. Brousseau, A. Bourdillon
A perspective in future radar systems is to perform target recognition to better control air traffic. In a military context, new technologies lead to the development of stealth targets, especially in conventional radar bands, which are additional difficulties for recognition. The use of the low frequency band, particularly near the resonance range for the considered targets, is a promising way to fight against radar cross section (RCS) reduction because stealth techniques are then difficult to implement. Indeed, the backscattered field induced by the target is the result of interactions between its different parts and it is less directive at lower frequency. It can then be assumed that the RCS signature of a given target is less sensitive to small aspect angle changes. Nevertheless, observations made with the monostatic multifrequency and multipolarization HF-VHF radar MOSAR show that small changes in aircraft flight route sometimes result in important RCS signature changes. The aim of this paper is to evaluate the influence of flight route on the RCS signature of commercial aircraft at low frequencies by means of computational models. First of all, the modeling of several aircraft is described and the accuracy of the modeling is discussed. Then, the models are used to evaluate the flight route effects in the low frequency band by studying different cases which take into account the flying height and spatial position of the aircraft. It is shown that an accurate knowledge of the aircraft flight route is required for aircraft identification.
{"title":"Study of flight route effects on aircraft RCS signature at VHF frequencies by means of wire grid models","authors":"D. Arnaud, C. Brousseau, A. Bourdillon","doi":"10.1109/RADAR.2000.851837","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851837","url":null,"abstract":"A perspective in future radar systems is to perform target recognition to better control air traffic. In a military context, new technologies lead to the development of stealth targets, especially in conventional radar bands, which are additional difficulties for recognition. The use of the low frequency band, particularly near the resonance range for the considered targets, is a promising way to fight against radar cross section (RCS) reduction because stealth techniques are then difficult to implement. Indeed, the backscattered field induced by the target is the result of interactions between its different parts and it is less directive at lower frequency. It can then be assumed that the RCS signature of a given target is less sensitive to small aspect angle changes. Nevertheless, observations made with the monostatic multifrequency and multipolarization HF-VHF radar MOSAR show that small changes in aircraft flight route sometimes result in important RCS signature changes. The aim of this paper is to evaluate the influence of flight route on the RCS signature of commercial aircraft at low frequencies by means of computational models. First of all, the modeling of several aircraft is described and the accuracy of the modeling is discussed. Then, the models are used to evaluate the flight route effects in the low frequency band by studying different cases which take into account the flying height and spatial position of the aircraft. It is shown that an accurate knowledge of the aircraft flight route is required for aircraft identification.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126098716","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}
Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851916
N. Levanon
A multifrequency radar signal is considered. It employs M subcarriers simultaneously. The subcarriers are phase modulated by different sequences that constitute a complementary set. Such a set can be constructed, for example, from the M cyclic shifts of a perfect phase-coded sequence of length M (e.g., P4). The subcarriers are separated by the inverse of the duration of a phase element by yielding orthogonal frequency division multiplexing (OFDM), well known in communications. The signal exhibits a thumbtack ambiguity function with delay resolution of t/sub h//M. The power spectrum is relatively flat, with width of M/t/sub h/. The signal can be constructed by power combining M fixed-amplitude signals. The resulting signal, however, is of variable amplitude.
{"title":"Multifrequency radar signals","authors":"N. Levanon","doi":"10.1109/RADAR.2000.851916","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851916","url":null,"abstract":"A multifrequency radar signal is considered. It employs M subcarriers simultaneously. The subcarriers are phase modulated by different sequences that constitute a complementary set. Such a set can be constructed, for example, from the M cyclic shifts of a perfect phase-coded sequence of length M (e.g., P4). The subcarriers are separated by the inverse of the duration of a phase element by yielding orthogonal frequency division multiplexing (OFDM), well known in communications. The signal exhibits a thumbtack ambiguity function with delay resolution of t/sub h//M. The power spectrum is relatively flat, with width of M/t/sub h/. The signal can be constructed by power combining M fixed-amplitude signals. The resulting signal, however, is of variable amplitude.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127616042","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}
Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851913
V. Vannicola, T. Hale, M. Wicks, P. Antonik
We evaluate the radar performance for chirp pulse (linear FM) trains in which the chirp rate is diverse from pulse to pulse. The evaluation consists of deriving the ambiguity function in generalized form for any number of pulses, pulse repetition rate, time bandwidth product, and diversity spread across the pulse train. Since each pulse has a different chirp rate, convolution and factorization cannot provide closed form expressions for the ambiguity functions of interest. However, numerical integration, programmed in MatLab, reveals the effects of the degree of chirp diversity and time bandwidth product on the waveform's ambiguity diagram. The recurrent lobe structure of the three-dimensional ambiguity diagram is of special interest. We present a simple formula for selecting the different chirp rates for particular diversity spreads. We conclude that a dramatic decrease in the range recurrent lobe level occurs as we increase the time bandwidth product and/or degree of chirp diversity.
{"title":"Ambiguity function analysis for the chirp diverse waveform (CDW)","authors":"V. Vannicola, T. Hale, M. Wicks, P. Antonik","doi":"10.1109/RADAR.2000.851913","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851913","url":null,"abstract":"We evaluate the radar performance for chirp pulse (linear FM) trains in which the chirp rate is diverse from pulse to pulse. The evaluation consists of deriving the ambiguity function in generalized form for any number of pulses, pulse repetition rate, time bandwidth product, and diversity spread across the pulse train. Since each pulse has a different chirp rate, convolution and factorization cannot provide closed form expressions for the ambiguity functions of interest. However, numerical integration, programmed in MatLab, reveals the effects of the degree of chirp diversity and time bandwidth product on the waveform's ambiguity diagram. The recurrent lobe structure of the three-dimensional ambiguity diagram is of special interest. We present a simple formula for selecting the different chirp rates for particular diversity spreads. We conclude that a dramatic decrease in the range recurrent lobe level occurs as we increase the time bandwidth product and/or degree of chirp diversity.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122833337","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}
Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851856
B. Spaulding, C. Nunn, M. Levitas
Certain models of sea clutter reflectivity establish a relationship between reflectivity and grazing angle in standard propagation conditions. This paper assumes that grazing angle maps uniquely to phase slope at the surface. A parabolic equation model is used to calculate the surface phase slope for both standard and nonstandard conditions. Lookup tables are calculated which relate phase shape to standard propagation grazing angle and this grazing angle is related to clutter reflectivity. The resulting clutter reflectivity is compared to reflectivity calculated by various empirical and non-empirical models.
{"title":"Sea clutter reflectivity in ducted propagation","authors":"B. Spaulding, C. Nunn, M. Levitas","doi":"10.1109/RADAR.2000.851856","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851856","url":null,"abstract":"Certain models of sea clutter reflectivity establish a relationship between reflectivity and grazing angle in standard propagation conditions. This paper assumes that grazing angle maps uniquely to phase slope at the surface. A parabolic equation model is used to calculate the surface phase slope for both standard and nonstandard conditions. Lookup tables are calculated which relate phase shape to standard propagation grazing angle and this grazing angle is related to clutter reflectivity. The resulting clutter reflectivity is compared to reflectivity calculated by various empirical and non-empirical models.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125061581","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}
Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851886
Liu Weixian, J. Fu
The Weibull clutter model offers the potential to accurately represent the real clutter distribution over a much wider range of conditions than other models. Schleher introduced a method to analyze the performance of radar detection in a Weibull background, but when considering M-pulses, the joint probability density function (PDF) becomes tediously long even as the samples are independent and identically distributed (IID). In this paper, a new way for estimation of the performance of CA-CFAR is developed as well as some other important results are provided.
{"title":"A new method for analysis of M-pulses CA-CFAR in Weibull background","authors":"Liu Weixian, J. Fu","doi":"10.1109/RADAR.2000.851886","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851886","url":null,"abstract":"The Weibull clutter model offers the potential to accurately represent the real clutter distribution over a much wider range of conditions than other models. Schleher introduced a method to analyze the performance of radar detection in a Weibull background, but when considering M-pulses, the joint probability density function (PDF) becomes tediously long even as the samples are independent and identically distributed (IID). In this paper, a new way for estimation of the performance of CA-CFAR is developed as well as some other important results are provided.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125143820","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}
Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851920
J. Guerci, S. Pillai
Recent advances in linear amplifier and arbitrary waveform generation technology have spawned interest in adaptive transmitter systems as a means for both optimizing target signal gain and enhancing ID. In this paper rigorous theoretical performance bounds are constructively established for the joint transmitter-target-channel-receiver optimization problem in the presence of additive colored noise (ACN), (e.g., interference multipath). For the ACN case, an analytical solution is obtained as an eigenvector (with associated maximum eigenvalue) of a homogeneous Fredholm integral equation of the second type. The kernel function is Hermitian and is obtained from the cascade of the target impulse response with the ACN whitening filter. The theoretical performance gains achievable over conventional transmitter strategies (e.g., chirp) are presented for various simulation scenarios including interference multipath mitigation. Also discussed is the potential effectiveness of an optimal discriminating pulse solution for the N-target ID problem that arises naturally from the theory.
{"title":"Theory and application of optimum transmit-receive radar","authors":"J. Guerci, S. Pillai","doi":"10.1109/RADAR.2000.851920","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851920","url":null,"abstract":"Recent advances in linear amplifier and arbitrary waveform generation technology have spawned interest in adaptive transmitter systems as a means for both optimizing target signal gain and enhancing ID. In this paper rigorous theoretical performance bounds are constructively established for the joint transmitter-target-channel-receiver optimization problem in the presence of additive colored noise (ACN), (e.g., interference multipath). For the ACN case, an analytical solution is obtained as an eigenvector (with associated maximum eigenvalue) of a homogeneous Fredholm integral equation of the second type. The kernel function is Hermitian and is obtained from the cascade of the target impulse response with the ACN whitening filter. The theoretical performance gains achievable over conventional transmitter strategies (e.g., chirp) are presented for various simulation scenarios including interference multipath mitigation. Also discussed is the potential effectiveness of an optimal discriminating pulse solution for the N-target ID problem that arises naturally from the theory.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125677259","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}
Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851904
E. Conte, A. De Maio, G. Ricci
This paper deals with radar detection of spatially distributed targets embedded in Gaussian noise with unknown covariance matrix. Precisely, noise returns are modeled as Gaussian vectors independent from range gate to range gate; they share the structure of the covariance matrix, but have possibly different power levels. A set of secondary data, free of signal components, is used to estimate the correlation properties of the disturbance. No a priori knowledge about the spatial distribution of the target scatterers is assumed. An adaptive detector is conceived and its performance is evaluated also in comparison with a previously proposed detection structure. Remarkably, the proposed receiver ensures CFAR-ness with respect to either the structure of the covariance matrix and the power backscattered from each cell. A performance assessment confirms its validity to operate in a heterogeneous environment.
{"title":"Space-time adaptive radar detection of distributed targets","authors":"E. Conte, A. De Maio, G. Ricci","doi":"10.1109/RADAR.2000.851904","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851904","url":null,"abstract":"This paper deals with radar detection of spatially distributed targets embedded in Gaussian noise with unknown covariance matrix. Precisely, noise returns are modeled as Gaussian vectors independent from range gate to range gate; they share the structure of the covariance matrix, but have possibly different power levels. A set of secondary data, free of signal components, is used to estimate the correlation properties of the disturbance. No a priori knowledge about the spatial distribution of the target scatterers is assumed. An adaptive detector is conceived and its performance is evaluated also in comparison with a previously proposed detection structure. Remarkably, the proposed receiver ensures CFAR-ness with respect to either the structure of the covariance matrix and the power backscattered from each cell. A performance assessment confirms its validity to operate in a heterogeneous environment.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129926305","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}
Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851853
B. Zheng, S. Changyin, Xing Mengdao
Inverse synthetic aperture radar (ISAR) imaging of a non-cooperative manoeuvring target is a challenging task due to its time-varying orientation and rotation velocity which denies accurate measurement. This paper investigates the general principles of ISAR imaging of manoeuvring targets, and proposes an algorithm for application in situations when the manoeuvrability is not too serious and the Doppler variation of sub-echoes from scatterers can be approximated as a first order polynomial. The imaging results using real data show the effectiveness of the new method.
{"title":"Principles and algorithms for inverse synthetic aperture radar imaging of manoeuvring targets","authors":"B. Zheng, S. Changyin, Xing Mengdao","doi":"10.1109/RADAR.2000.851853","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851853","url":null,"abstract":"Inverse synthetic aperture radar (ISAR) imaging of a non-cooperative manoeuvring target is a challenging task due to its time-varying orientation and rotation velocity which denies accurate measurement. This paper investigates the general principles of ISAR imaging of manoeuvring targets, and proposes an algorithm for application in situations when the manoeuvrability is not too serious and the Doppler variation of sub-echoes from scatterers can be approximated as a first order polynomial. The imaging results using real data show the effectiveness of the new method.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133851319","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}
Pub Date : 2000-05-07DOI: 10.1109/RADAR.2000.851894
M. Denny
In this paper, we present results on the consequences of refracted propagation for airborne radar mathematical modeling. That is, given an atmosphere of varying refractive index, the path of EM radiation is curved in general; we look at the effects this has upon radar performance, and at how such effects are to be modeled. An effective Earth radius factor k is derived that is valid for all airborne radar altitudes, and which reduces to the familiar k=4/3 value at low altitudes. Horizon ranges are calculated numerically and analytically. Radius of curvature is determined, and the consequences of curved paths for elevation beamshape loss and range gating is discussed. Loss calculations are presented, and modeling implementation considerations are summarized.
{"title":"Refracted propagation effects for airborne radar","authors":"M. Denny","doi":"10.1109/RADAR.2000.851894","DOIUrl":"https://doi.org/10.1109/RADAR.2000.851894","url":null,"abstract":"In this paper, we present results on the consequences of refracted propagation for airborne radar mathematical modeling. That is, given an atmosphere of varying refractive index, the path of EM radiation is curved in general; we look at the effects this has upon radar performance, and at how such effects are to be modeled. An effective Earth radius factor k is derived that is valid for all airborne radar altitudes, and which reduces to the familiar k=4/3 value at low altitudes. Horizon ranges are calculated numerically and analytically. Radius of curvature is determined, and the consequences of curved paths for elevation beamshape loss and range gating is discussed. Loss calculations are presented, and modeling implementation considerations are summarized.","PeriodicalId":286281,"journal":{"name":"Record of the IEEE 2000 International Radar Conference [Cat. No. 00CH37037]","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2000-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132658376","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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