Clutter rejection limitations from ambiguous range clutter
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Limitations on achievable clutter rejection due to ambiguous range clutter are described. The profile of clutter power versus range is shown to limit achievable clutter rejection. Ambiguous range effects are discussed in the context of sea clutter, using a model that includes propagation conditions, and rain clutter. Limitations in moving target indication systems are illustrated for sea clutter, where propagation is subject to evaporation ducts. Benefits of fill pulses are illustrated for rain and sea clutter.< Keywords:
Radar horizon
Traditional constant false alarm rate (CFAR) methods have shown their potential for foreign object debris (FOD) indication. However, the performance of these methods would deteriorate under the complex clutter background in airport scenes. This paper presents a threshold-improved approach based on the cell-averaging clutter-map (CA-CM-) CFAR and tests it on a millimeter-wave (MMW) radar system. Clutter cases are first classified with variability indexes (VIs). In homogeneous background, the threshold is calculated by the student-t-distributed test statistic; under the discontinuous clutter conditions, the threshold is modified according to current VI conditions, in order to address the performance decrease caused by extended clutter edges. Experimental results verify that the chosen targets can be indicated by the t-distributed threshold in homogeneous background. Moreover, effective detection of the obscured targets could also be achieved with significant detectability improvement at extended clutter edges.
Extremely high frequency
Statistic
Detection threshold
False alarm
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Abstract In this paper, attention is devoted to the analysis of the detection threshold based on the multi‐frame integration in heavy‐tailed clutter for the radar with high resolution and even smaller grazing angle. The closed‐form expressions of both the probability of the detection and the probability of false alarm for the heavy‐tailed clutter background, which can be used for the theoretical analysis of constant false alarm rate (CFAR) detectors, are derived with the multi‐frame integration technique. Accordingly, an improved CFAR detector is designed to work well with the presence of target‐like outliers in the heavy‐tailed clutter. In addition, the proposed CFAR detector is capable to alleviate the masking‐effect resorting to the additive feedback operation when a target is large enough to cross several cells in multi‐target case. The theoretical analysis and numerical simulations demonstrate that the proposed CFAR detector based on multi‐frame integration can improve the signal‐to‐clutter rate of the targets exhibiting better performance than ones based on single frame in heavy‐tailed clutter background. It is validated from the simulations that the proposed CFAR detector with additive feedback operation can deal with masking‐effect for large target occupying several cells.
False alarm
Moving target indication
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This paper studies the performance of a cell-averaging constant false alarm rate (CA-CFAR) receiver that operates in a nonhomogeneous clutter environment with impulsive, heavy-tailed statistics. The clutter distribution is modeled by a positive alpha-stable distribution, which is described by the characteristic exponent α, where 0 <; α <; 1. Analytical expressions for the false alarm and detection probabilities are derived for arbitrary values of α assuming a nonhomogeneous clutter background. The analytical results are validated with computer simulation.
False alarm
Shape parameter
K-distribution
Radar detection
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Mitigation of clutter due to sidelobe and mainlobe of antenna in airborne radars is of paramount importance for detection of moving targets. In this paper, an algorithm based on mathematical morphology is proposed to remove clutter from range - Doppler image. Clutter spread in range as well as Doppler due to motion of platform and clutter characteristics are dependent on range. The proposed algorithm extracts the clutter region without training or prior knowledge of the clutter spectrum. Morphological processing is applied on range-Doppler image to find the connected components of detections from constant false alarm rate (CFAR) processing. The identified connected components form the clutter image which is then used to remove false detections due to clutter. The proposed algorithm is compared with conventional sidelobe blanking algorithm and has shown better performance.
Stationary target indication
Moving target indication
Radar horizon
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Automatic detection radars require some method of adapting to variations in the background clutter in order to control their false-alarm rate. Conventional cell-averaging techniques designed to maintain a constant false-alarm rate in Rayleigh clutter will fail to control the false-alarm rate in more severe clutter environments such as log-normal or Weibull clutter. A processor is described which is capable of maintaining false-alarm regulation in log-normal clutter and in Weibull clutter (and, under certain conditions, over the entire family of log-normal and Weibull distributions).
Rayleigh distribution
Shape parameter
False alarm
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A feasible Constant False Alarm Rate(CFAR) detector based on Anderson-Darling(AD) test for multiple interfering targets and clutter edge scenarios is proposed and referred as AD-CFAR,which chooses reference cell length and detection strategy adaptively according to characteristic of input clutter serials. AD-CFAR exploits K-sample Anderson-Darling hypothesis test to censor clutter blocks needed for clutter power estimation,and then Anderson-Darling test is employed for distribution test of the resultant homogenous clutter to select the proper detection algorithm from the strategy library. Theoretical analysis indicates that the proposed AD-CFAR maintains similar performance in homogeneous clutter to CA-CFAR and achieves excellent detection and false alarm performance in multiple interfering targets or clutter edge situation even when both are present.
Anderson–Darling test
Statistical power
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This work deals with a target detection algorithm for multistatic and multiple input - multiple output radars. The adopted algorithm is able to keep the false alarm rate constant, if the disturbance samples associated to each receiver-transmitter pair are distributed according to a Compound-Gaussian model. In particular, we analyze the performance of the adopted detection algorithm, in order to evaluate the impact of clutter diversity on the detection performance. To this aim, we simulated the clutter samples by varying the shape parameter of the clutter distribution associated to each receiver-transmitter pair. The results highlight that clutter diversity has a strong impact on the detection performance. In the case of two channels, i.e. two receiver-transmitter pairs, a significant result is that the same value of the probability of the detection is obtained for different couples of the shape parameters associated to the two channels.
False alarm
Stationary target indication
Statistical power
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A statistical model for the complex data of high range resolution surface radars is proposed that incorporates range coherence in both the clutter and target. The clutter is modeled using two distributions: a background clutter distribution and wave clutter distribution. The model is then used to develop a multi-hypothesis detector that discriminates between targets, wave clutter, and background clutter. Performance on real surface radar data shows that this technique reduces false alarms due to wave clutter spikes more effectively than the cell-averaging constant false alarm rate (CA-CFAR) detector that operates on the amplitude data using a composite clutter model.
Radar horizon
Stationary target indication
Moving target indication
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AbstrcatA novel biparametric OS-CFAR(BOS-CFAR) detection method for AEW radar in the sea clutter is proposed.The performance is discussed and analyzed for multiple-pulse noncoherent integration when this method operates in the multiple-target environment in the non-Gaussian sea clutter background. Theoretical analysis and simulation result show that the proposed method can enhance the CFAR detection performance for AEW radar in the sea clutter background effectively.
Radar detection
Radar horizon
Stationary target indication
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The problem of constant false alarm rate(CFAR) detection under Pearson distribution clutter is studied in this paper.We derive the exact elementary expressions of probability of false alarm for cell averaging(CA)-CFAR,greatest of(GO)-CFAR and smallest of(SO)-CFAR in homogenous background,and prove that these detectors are also of CFAR.The performance of these detectors are evaluated both in homogeneous and non-homogeneous clutter.The results show that the SO-CFAR has the best detection performance against uniform clutter background and multiple target environments,while the GO-CFAR has the best control ability of false alarm against clutter edges.
Statistical power
False alarm
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