- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Significant Wave Height Retrieval from Gaofen-3 Wave Mode Images
摘要： Significant wave height (Hs), is an important parameter, represented as the integration of directional wave spectra. Although many researchers have directly extracted Hs from SAR images and got a great accuracy of retrieval, those approaches are not suitable for GF-3 SAR data. In this paper, we propose an empirical approach for SAR Hs retrieval, using λc estimated from the real part of image cross spectra obtain from VV-polarized Gaofen-3 (GF-3) wave mode data acquired in different radar beams (called wave-code). Results using GF-3 wave mode data from January to February 2017 indicate that the bias and RMSE errors are: 189 wave-code, -0.13 m and 0.57 m; 190 wave-code, -0.07 m and 0.34 m; 193 wave-code, -0.3 m and 0.59 m; 199 wave-code, 0.16 m and 0.68 m; 215 wave-code, 0.2 m and 0.87 m. they show a relative behavior between the retrieved Hs and the Hs extracted from WAVEWATCH-III (WW3). However, there is a significant error when WW3-extracted Hs exceed 4 m. It seems that the model is not suitable for Hs retrieval on high sea conditions.
关键词： wave empirical retrieval,GF-3,cutoff wavelength estimation,synthetic aperture radar,wave mode
更新于2025-09-23 15:22:29
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Compact Real-Time Inter-Frame Histogram Builder for 15Bits High-Speed ToF-Imagers based on Single-Photon Detection
摘要： Time-of-flight image sensors based on single-photon detection, i.e. SPADs, require some filtering of pixel readings. Accurate depth measurements are only possible if the jitter of the detector is mitigated. Moreover, the time stamp needs to be effectively separated from uncorrelated noise such as dark counts and background illumination. A powerful tool for this is building a histogram of a number of pixel readings. Future generation of ToF imagers are seeking to increase spatial and temporal resolution along with the dynamic range and frame rate. Under these circumstances, storing the complete histogram for every pixel becomes practically impossible. Considering that most of the information contained by the histogram represents noise, we propose a highly efficient method to store just the relevant data required for ToF computation. This method makes use of the shifted inter-frame histogram (SifH). It requires a memory as low as 128 times smaller than storing the complete histogram if the pixel values are coded on up to 15 bits. Moreover, a fixed 28 words memory is enough to process histograms containing up to 215 bins. In exchange, the overall frame rate only decreases to one half. The hardware implementation of this algorithm is presented. Its remarkable robustness for a low SNR of the ToF estimation is demonstrated by Matlab simulations and FPGA implementation using input data from a SPAD camera prototype.
关键词： shifted inter-frame histogram (SifH),single-photon avalanche-diode (SPAD),real-time time-of-flight (ToF) estimation,ToF image sensor
更新于2025-09-23 15:22:29
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Deformation Estimation for Time Series InSAR Using Simulated Annealing Algorithm
摘要： Time series interferometric synthetic aperture radar SAR (TSInSAR) is one of the most important surface deformation monitoring techniques, and has been widely used in geodesy. Deformation estimation is one of the main steps of TSInSAR processing, so an effective and efficient algorithm is necessary. Present algorithms have some limitations such as computing costs or errors caused by local extremums. In this work, a novel deformation estimation method based on the simulated annealing (SA) algorithm is proposed to handle this problem. The SA algorithm uses a random search to avoid local extremums and thus can be more likely to get the global optimal solution of deformation. By adopting a better annealing method, this algorithm gets high precision deformation results in less time than most present algorithms. In addition, it can estimate complex nonlinear deformation without adding any computing costs. The results, tested on the real SAR data, confirm the reliability and effectiveness of the SA-based deformation estimation algorithm.
关键词： InSAR,deformation parameter estimation,simulated annealing,TSInSAR
更新于2025-09-23 15:22:29
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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe, Japan (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - Parameter Estimation for Rayleigh-Pearson Mixture Model Based on Expectation-Maximization Algorithm
摘要： In this paper I propose a mixture distribution model with Rayleigh and Pearson distributions in order to represent the statistics of the reverberation. In addition the paper studies a parameter estimation method for the mixture distribution. As a preliminary step the parameter estimation of Pearson distribution is studied. Then the method of the parameter estimation is derived in the Rayleigh-Pearson mixture model based on the expectation-maximization (EM) technique. Simulation results have demonstrated that the parameter estimation method provides adequate performance.
关键词： Pearson distribution,parameter estimation,EM algorithm,mixture distribution
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - Sheffield (2018.7.8-2018.7.11)] 2018 IEEE 10th Sensor Array and Multichannel Signal Processing Workshop (SAM) - Super-Resolution Pulse-Doppler Radar Sensing via One-Bit Sampling
摘要： This paper investigates the delay-Doppler estimation problem of a pulse-Doppler radar which samples and quantizes the noisy echo signals to one-bit measurements. By applying a multichannel one-bit sampling scheme, we formulate the delay-Doppler estimation as a structured low-rank matrix recovery problem. Then the one-bit atomic norm soft-thresholding method is proposed to recover the low-rank matrix, in which a surrogate matrix is properly designed to evaluate the proximity of the recovered data to the sampled one. With the recovered low-rank matrix, the delays and Doppler frequencies can be determined and paired. Numerical experiments are performed to demonstrate the effectiveness of our method compared with the one-bit sparse signal recovery method based on discrete dictionary.
关键词： Delay-Doppler estimation,atomic norm,compressive sensing,1-bit quantization
更新于2025-09-23 15:22:29
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[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - A High Frequency Vibration Compensation Approach in Terahertz SAR Based on Wavelet Multi-Resolution Analysis
摘要： The use of terahertz wave in SAR imaging can solve the difficulties of frame rate and detection of slow moving targets in conventional SAR imaging. The most important difference between terahertz SAR (THz-SAR) and conventional SAR is the treatment on motion compensation. For reason that the wavelength of terahertz SAR is much shorter than that of conventional microwave SAR, the tiny vibration of SAR platform will blur SAR images, especially high frequency components. The high frequency vibration will result in paired echoes in SAR imaging, which can't be focused with traditional SAR imaging algorithms. Thus the vibration parameters can't be estimated precisely enough to construct the reference function to compensate the sinusoidal modulation phase. So we first get focused paired echoes in terahertz SAR imaging through Doppler keystone transform (DKT), then we propose a frequency estimation method based on wavelet multi-resolution analysis, along with parametric space projection method, to complete the high frequency vibration estimation of terahertz SAR. At last, the numerical tests using the point target echoes validate the proposed method.
关键词： synthetic aperture radar,high frequency vibration error,Terahertz,wavelet multi-resolution analysis,vibration estimation
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Radar (RADAR) - Brisbane, Australia (2018.8.27-2018.8.31)] 2018 International Conference on Radar (RADAR) - Fast Direction-of-Arrival Estimation in Coprime Arrays
摘要： We present a fast direction-of-arrival (DOA) estimation algorithm for coprime array structures. In many practical applications of radar signals processing, reducing the redundancy inherent in linear arrays is advantageous. Arrays employing a coprime-pair configuration offer an increased number of degrees of freedom and permit the detection of more sources than sensors. Traditionally, this is achieved using conventional subspace-based methods. While these methods, such as MUltiple Signal Classification (MUSIC), are capable of high-resolution, the computational complexity of these algorithms is a significant hindrance to their practical implementation as the number of sensors increases. Furthermore, they must resort to spatial smoothing in order to calculate the covariance matrix. We, on the other hand, propose a fast iterative interpolated beamforming algorithm that has a computational complexity of the same order as the fast Fourier transform (FFT). The proposed approach is capable of delivering high fidelity DOA estimates that outperform the traditional high resolution methods. Simulation results demonstrate the DOA estimation performance of the technique.
关键词： SNR,coprime arrays,FIIB,DOA estimation,MUSIC
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Chongqing (2018.6.27-2018.6.29)] 2018 IEEE 3rd International Conference on Image, Vision and Computing (ICIVC) - Vision-Based Simultaneous Localization and Mapping on Lunar Rover
摘要： With the development of lunar exploration technology, vision-based navigation technology has become a research focus in the field of lunar rover. This paper proposes an image-based method for localization and mapping with a lunar rover. The motion of the camera represents the movement of the lunar rover. Based on the images acquired by the camera, the relative pose of the camera and 3D landmarks are obtained using the multi-view geometry and the bundle adjustment optimization methods. The prior knowledge of the lunar rover movement is not required. In addition, this paper also proposes a grid-based feature extraction method to solve the problem of uneven feature extraction and mis-matching. The algorithm in this paper has been tested in real time in a large image dataset. Finally, the error analysis of the estimated pose obtained from the experiment and the real trajectory proves the excellent performance of the algorithm.
关键词： localization and mapping,lunar exploration,lunar rover,feature extraction,pose estimation
更新于2025-09-23 15:22:29
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Beam-Doppler Unitary ESPRIT for Multitarget DOA Estimation
摘要： High-resolution direction of arrival (DOA) estimation is a critical issue for mainbeam multitarget tracking in ground-based or airborne early warning radar system. A beam-Doppler unitary ESPRIT (BD-UESPRIT) algorithm is proposed to deal with this problem. Firstly, multiple snapshots without spatial aperture loss are obtained by using the technique of time-smoothing. Then the conjugate centrosymmetric discrete Fourier transform (DFT) matrix is used to transform the extracted data into beam-Doppler domain. Finally, the rotational invariance property of the space-time beam is exploited to estimate DOA of the target. The DOA estimation accuracy is improved greatly because the proposed algorithm takes full advantage of temporal information of the signal. Furthermore, the computational complexity of the presented algorithm is reduced dramatically, because the degree of freedom after beam transformation is very small and most of the operations are implemented in real-number domain. Numerical examples are given to verify the effectiveness of the proposed algorithm.
关键词： computational complexity,DOA estimation,time-smoothing,ESPRIT,beam-Doppler domain
更新于2025-09-23 15:22:29
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Optical Wireless Communication Based Indoor Positioning Algorithms: Performance Optimisation and Mathematical Modelling
摘要： In this paper, the performance of the optimal beam radius indoor positioning (OBRIP) and two-receiver indoor positioning (TRIP) algorithms are analysed by varying system parameters in the presence of an indoor optical wireless channel modelled in line of sight configuration. From all the conducted simulations, the minimum average error value obtained for TRIP is 0.61 m against 0.81 m obtained for OBRIP for room dimensions of 10 m × 10 m × 3 m. In addition, for each simulated condition, TRIP, which uses two receivers, outperforms OBRIP and reduces position estimation error up to 30%. To get a better understanding of error in position estimation for different combinations of beam radius and separation between light emitting diodes, the 90th percentile error is determined using a cumulative distribution frequency (CDF) plot, which gives an error value of 0.94 m for TRIP as compared to 1.20 m obtained for OBRIP. Both algorithms also prove to be robust towards change in receiver tilting angle, thus providing flexibility in the selection of the parameters to adapt to any indoor environment. In addition, in this paper, a mathematical model based on the concept of raw moments is used to confirm the findings of the simulation results for the proposed algorithms. Using this mathematical model, closed-form expressions are derived for standard deviation of uniformly distributed points in an optical wireless communication based indoor positioning system with circular and rectangular beam shapes.
关键词： position estimation,channel modelling,raw moments,optical wireless communication,indoor positioning system,cumulative distribution frequency,standard deviation
更新于2025-09-23 15:22:29