This paper studies GPS receiver anti-spoofing jamming problems. Unlike blanket jamming, spoofing jamming is hidden because its power level below noise floor. Besides, spoofing jamming has the same format with satellit...
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ISBN:
(纸本)9783642547362
This paper studies GPS receiver anti-spoofing jamming problems. Unlike blanket jamming, spoofing jamming is hidden because its power level below noise floor. Besides, spoofing jamming has the same format with satellite signals. A designed spoofing jamming can guide GPS receiver positioning errors occurred and change its navigation line. The existing jamming suppression methods of satellite navigation systems are more suitable for blanket jamming suppression, while for spoofing jamming suppression, these methods are almost invalid. The current published literature make the spoofing jamming detection technology as the major research direction, and rarely involve how to suppress spoofing jamming. This paper analyzes the characteristics of repeater spoofing jamming. For one and multiple of repeater spoofing jamming scenarios, beam forming and RELAX algorithm are proposed to estimate the DOA (Direction of Arrival) of spoofing jamming respectively. After detecting the DOA of spoofing jamming, GPS receiver can steer nulling to the direction of spoofing jamming and suppress spoofing jamming by constructing the projection matrix of spoofing jamming. Simulation experiments prove the correctness and the effectiveness of the two methods.
Multipath effect of signals is one of the main causes of the global positioning system positioning error. Although the differential technology can improve the positioning accuracy of navigation system. However, due to...
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ISBN:
(纸本)9783642547362
Multipath effect of signals is one of the main causes of the global positioning system positioning error. Although the differential technology can improve the positioning accuracy of navigation system. However, due to the reference station and the user's geographical location is different;Differential GPS (DGPS) system still does not eliminate multipath effects of the satellite signal. The conventional narrow correlator method can reduce positioning error. But it assumes that the bandwidth of channel is unlimited. It can not be met in practice. That is its limitations. In this paper, we consider the characteristics of GPS signal model and the multipath effect In GPS system. We introduce a least-squares iterative multipath super-resolution (LIMS) delay estimation algorithm and propose a multipath signal delay estimation algorithm based on correlation model on this basis. The algorithm takes the correlation output of received signal correlates and the local C /A code as the model, estimates the direct signal and the multipath signal delay accurately in the condition of signal delay is unknown. As can be seen from the simulation results, the multipath interference suppression algorithm we propose outperforms the traditional narrow correlator method and LIMS algorithms.
In the complex electromagnetic environment, the Global Navigation Satellite System(GNSS) wasseriously influenced by the interference. The anti-jammingalgorithm based on the uniform array have been widely used in GNSS ...
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In the complex electromagnetic environment, the Global Navigation Satellite System(GNSS) wasseriously influenced by the interference. The anti-jammingalgorithm based on the uniform array have been widely used in GNSS interference suppression technology, but the number of the interference is limited by the number of the antenna sensor. This paper proposed an interference suppression algorithm based on the extended array, the algorithm could suppress more interference than the number of antenna sensor. Firstly, the covariance matrix of the non-uniform array is vectorized. After that, the spatial smoothing is used to build up the rank of the covariance matrix. With the smoothed covariance matrix, power inversion algorithm is used to estimate the directions of the interference. Then, forming an overdetermined equation based on the interference subspace and an arbitrary signal's steering vector, whose direction is different form the interference. Finally, solving its least-squares solution to get the optimal weight, which can form nulls in the direction of interference without affecting the useful signal. The simulation results verify the effectiveness of the proposed algorithm.
Tropical cyclone(TC) center location or eye fix is the first and inevitable procedure in TC forecasting,but mostly done manually in *** we present a novel and objective method to locate TC center by compensating conve...
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Tropical cyclone(TC) center location or eye fix is the first and inevitable procedure in TC forecasting,but mostly done manually in *** we present a novel and objective method to locate TC center by compensating conventional pattern matching and vector field analysis methods *** experimental results show satisfactory results in comparison with the best track data from the China Meteorological Administration especially when the spiral patterns of TC are well *** method being introduced,TC forecasters can fix TC eye objectively and easily from data of all kinds of meteorological satellites.
In this paper,a blind adaptive beamforming algorithm for Global Positioning System(GPS) is proposed,which combines the cyclic adaptive beamforming(CAB) algorithm with subspace *** with the CAB algorithm,the new algori...
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In this paper,a blind adaptive beamforming algorithm for Global Positioning System(GPS) is proposed,which combines the cyclic adaptive beamforming(CAB) algorithm with subspace *** with the CAB algorithm,the new algorithm can generate high gain toward the satellite direction and form the nulls in the directions of jammers by constraining both the weight vector and control vector of the CAB algorithm to the orthogonal space of the steering vectors of *** proposed algorithm has the advantages such as no requirement of any knowledge of the transmitted signals and the satellite locations,fast convergence speed,and low computation *** results are provided to demonstrate the performance of the proposed algorithm.
Space-Time Adaptive processing(STAP) is an effectivemethod to suppress interference in Global Navigation Satellite System(GNSS).But in high-dynamic environment, conventional adaptive anti-jamming algorithms are invali...
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Space-Time Adaptive processing(STAP) is an effectivemethod to suppress interference in Global Navigation Satellite System(GNSS).But in high-dynamic environment, conventional adaptive anti-jamming algorithms are invalid since jammers may easily move out of the array pattern nulls. To solve this problem, a new null-widen method based on the Laplace distribution model is deduced in this paper, the method can get wider null at direction of *** this method is computationally intensive by using STAP, thus a new null-widen method based on reduced-dimension multistage wiener filters(MWF) is deduced here. It has proved in simulation section that the new method can get better performance in few snapshots.
Airborne weather radars are used by pilots to identify areas containing significant precipitation, turbulence, and wind shear on the flight path. The different atmospheric hazards can be determined by airborne weather...
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ISBN:
(纸本)9781509021505
Airborne weather radars are used by pilots to identify areas containing significant precipitation, turbulence, and wind shear on the flight path. The different atmospheric hazards can be determined by airborne weather radar using the spectral moments of radar echoes. The pulse pair processing method and the FFT based method are the most widely used spectral moments estimators. However, the performance of these method is poor under low SNR conditions as it is a nonparametric method. A parametric spectral moments estimation method is proposed based on subspace analysis of the covariance matrix of the echoes with Gaussian-shaped spectrum. A fast algorithm for this method is also implemented for demonstration, in which the 2D-search problem is decomposed into two 1D-search routines. The numerical analysis verifies that the presented method functions effectively in low SNR scenario.
In Global navigation satellite systems(GNSS),when the receiver carrier is in the situation of attitude high dynamic,the directions of arrival(DOA)of signal and interference will change rapidly over *** this point,conv...
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ISBN:
(纸本)9789811009334
In Global navigation satellite systems(GNSS),when the receiver carrier is in the situation of attitude high dynamic,the directions of arrival(DOA)of signal and interference will change rapidly over *** this point,conventional adaptive anti-jamming algorithms become *** this paper,According to the structure shape of practical attitude high dynamic carrier,the DOAs changes of signal and interference in the case of uniform circular array are analyzed,and the Capon-Laplace algorithm based on uniform circular array(UCA)was provided to suppress the *** effectiveness of the algorithm is verified by simulation *** the analysis of attitude high-dynamic parameter,the paper compared the feasibility of the algorithm in different degrees’attitude highdynamic circumstances,giving a further verification on the effectiveness of the algorithm.
This paper proposes a novel lightweight SAR aircraft detection network (Lightweight SAR-Aircraft Network LSAN) based on YOLOv8n. In the backbone and neck part of the network, we design a lightweight feature extraction...
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ISBN:
(数字)9798350360325
ISBN:
(纸本)9798350360332
This paper proposes a novel lightweight SAR aircraft detection network (Lightweight SAR-Aircraft Network LSAN) based on YOLOv8n. In the backbone and neck part of the network, we design a lightweight feature extraction module with Efficient Multiscale Attention Module (EMA) to reduce the network parameters and computation cost. A multiscale Discrete semantic Feature Enhancement Module (DFEM) is added in the neck to enhance the capability of feature extraction. Experimental results on the China GF-3 SAR datasets demonstrate that the proposed algorithm achieves 98.1% mAP
50
and 82.1% mAP
50-95
at a speed of 122 FPS. Compared to the YOLOv8n model, LSAN shows an improvement of 1.4% in mAP
50
and 4.8% in mAP
50-95
. In particular, there is a reduction of 68.6% in the parameters and 30.8% of FLOPs. Also, experiments on other public SAR datasets demonstrate the generalization and effectiveness of our method.
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