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Improved spectrum reconstruction technique based on chirp rate modulation in stepped-frequency SAR

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Science China(Information Sciences) 2015年第10期58卷 148-158页

作者： GAO WenBin DING ZeGang ZHU DongLin ZENG Tao LONG Teng Radar Research Laboratory School of Information and Electronics

To improve the efficiencies of the traditional spectrum reconstruction techniques, an improved spectrum reconstruction technique(ISRT) based on chirp rate modulation(CRM) is proposed. With the help of a CRM operation, a reconstructed wideband signal with a narrow pulse width can be obtained. Compared with the traditional time domain spectrum reconstruction technique(TSRT), ISRT is less time-consuming since much less samples are needed. Compared with the traditional frequency domain spectrum reconstruction technique(FSRT), the reconstructed signal is a chirp signal, which has no limitation on the subsequent imaging *** is more, processing steps of ISRT are optimized, and the computational burden is less than that of TSRT and FSRT. Both simulation results and real data processing have verified the validity of ISRT.

关键词： chirp rate modulation(CRM) spectral efficiency improved spectrum reconstruction technique(ISRT) spectrum reconstruction stepped-

spectrum reconstruction and the performance analysis for multichannel bidirectional SAR

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Science China(Information Sciences) 2015年第8期 25-37页

作者： MA XiLe DONG Zhen HE Feng SUN ZaoYu LIANG DianNong School of Electronic Science and Engineering National University of Defense Technology

Single-channel bidirectional synthetic aperture radar(Bi Di-SAR) systems require the pulse repetition frequency(PRF) to be cautiously designed. Firstly, it should be higher than the total bandwidth of the two Doppler subbands; secondly, it should be carefully selected so that the two Doppler subbands are properly located. We introduce multichannel Bi Di-SAR imaging mode to realize bidirectional high resolution wide swath(HRWS) imaging. Acquisition geometry of multichannel Bi Di-SAR is interpreted. Doppler spectrum of Bi DiSAR consists of two subbands with limited bandwidth. Based on a prior knowledge about the location of the Doppler subbands, we derive the method for separating the aliased Doppler spectra for general PRFs. Then,we analyze the reconstruction performance in terms of azimuth ambiguity to signal ratio(AASR) and signal to noise ratio(SNR). Besides, we propose to use a properly designed sparse array antenna to improve the azimuth ambiguity performance. Validity of the signal processing method is verified by simulation results.

关键词： bidirectional synthetic aperture radar(Bi Di-SAR) multichannel sparse array antenna spectrum reconstruction performance analysis

Efficient DPCA SAR imaging with fast iterative spectrum reconstruction method

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Science China(Information Sciences) 2012年第8期55卷 1838-1851页

作者： FANG Jian1,ZENG JinShan1,XU ZongBen1&ZHAO Yao2 1M inistry of Education Key Lab for Intelligent Networks and Network Security Xi'an Jiaotong University,Xi'an 710049,China 2N ational Key Laboratory of Science and Technology on Microwave Imaging&Institute of Electronics,Chinese Academy of Sciences,Beijing 100049,China 1. Ministry of Education Key Lab for Intelligent Networks and Network Security Xi’an Jiaotong University Xi’an 710049 China2. National Key Laboratory of Science and Technology on Microwave Imaging & Institute of Electronics Chinese Academy of Sciences Beijing 100049 China

The displaced phase center antenna(DPCA)technique is an effective strategy to achieve wide-swath synthetic aperture radar(SAR)imaging with high azimuth ***,traditionally,it requires strict limitation of the pulse repetition frequency(PRF)to avoid non-uniform ***,any deviation could bring serious ambiguity if the data are directly processed using a matched *** break this limitation,a recently proposed spectrum reconstruction method is capable of recovering the true spectrum from the nonuniform ***,the performance is sensitive to the selection of the *** regularization based imaging may provide a way to overcome this *** existing time-domain method,however,requires a large-scale observation matrix to be built,which brings a high computational *** this paper,we propose a frequency domain method,called the iterative spectrum reconstruction method,through integration of the sparse regularization technique with spectrum analysis of the DPCA *** approximately expressing the observation in the frequency domain,which is realized via a series of decoupled linear operations,the method performs SAR imaging which is then not directly based on the observation matrix,which reduces the computational cost from O(N2)to O(N log N)(where N is the number of range cells),and is therefore more efficient than the time domain *** sparse regularization scheme,realized via a fast thresholding iteration,has been adopted in this method,which brings the robustness of the imaging process to the PRF *** provide a series of simulations and ground based experiments to demonstrate the high efficiency and robustness of the *** simulations show that the new method is almost as fast as the traditional mono-channel algorithm,and works well almost independently of the PRF ***,the suggested method can be accepted as a practical and efficient wide-swath SAR imaging technique.

关键词： displaced phase center antenna sparse regularization iterative thresholding spectrum reconstruction

Symmetrical Processing of Interferogram and spectrum reconstruction in Interference Spectrometer

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Journal of Beijing Institute of Technology 2003年第1期12卷 1-5页

作者：楚建军赵达尊 National Laboratory of Color Science and Engineering Beijing Institute of Technology Beijing100081China

Because of its all-reflective layout based on the Fresnel double-mirror interference system, the newly developed Fourier transform imaging spectrometer has a very large spectral bandwidth ranged from a cut-off wavelength (related to the cut-off wave number σ max ) to far infrared. According to the signal's symmetry and wide-band characteristics, a simple method that can efficiently weaken the low frequency noise in the reconstructed spectrum is presented. Also, according to the symmetry, the eigenvector method is applied to the reconstruction of the spectrum.

关键词： Fourier transform interferential imaging spectrometer spectrum reconstruction power spectrum estimation

FAST ALGORITHM FOR NON-UNIFORMLY SAMPLED SIGNAL spectrum reconstruction

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Journal of Electronics(China) 2013年第3期30卷 231-236页

作者： Zhu Zhenqian Zhang Zhimin Wang Yu Institute of Electronics Chinese Academy of Sciences University of Chinese Academy of Sciences (UCAS)

In this paper, a fast algorithm to reconstruct the spectrum of non-uniformly sampled signals is proposed. Compared with the original algorithm, the fast algorithm has a higher computational efficiency, especially when sampling sequence is long. Particularly, a transformation matrix is built, and the reconstructed spectrum is perfectly synthesized from the spectrum of every sampling channel. The fast algorithm has solved efficiency issues of spectrum reconstruction algorithm, and making it possible for the actual application of spectrum reconstruction algorithm in multi-channel Synthetic Aperture Radar (SAR).

关键词： Synthetic Aperture Radar (SAR) Non-uniform sampling Multi-channel SAR spectrum reconstruction High-resolution and wide-swath

Visible-to-near-infrared spectrum reconstruction with dielectric metasurfaces

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Chinese Optics Letters 2024年第9期22卷 137-141页

作者： Kaikai Gao Peiyang Li Jiayi Wang Sheng Liu Peng Li Dexing Yang Jianlin Zhao Dandan Wen Key Laboratory of Light Field Manipulation and Information Acquisition Ministry of Industry and Information Technologyand Shaanxi Key Laboratory of Optical Information TechnologySchool of Physical Science and TechnologyNorthwestern Polytechnical UniversityXi’an 710129China

The miniaturization of spectrometers has received much attention in recent *** rapid development of metasurfaces has provided a new avenue for creating more compact and lightweight ***,most metasurface-based spectrometers operate in the visible light region,with much less research on near-infrared *** is possibly caused by the lack of effective metasurface filters for the near-infrared *** design and fabricate a polarizationinsensitive amorphous silicon metasurface that exhibits unique transmission spectra in parts of the visible and nearinfrared *** passing the light to be measured through a metasurface filter array and measuring the transmitted power,we achieve the precise reconstruction of unknown spectra in the visible and near-infrared range(450-950 nm)using an algorithm matched to the filter *** approach is a step towards miniaturized spectrometers within the visible-to-near-infrared range based on metasurface filter arrays.

关键词： metasurfaces filters spectrum reconstruction algorithm.

ICA METHOD IN spectrum reconstruction

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ICA METHOD IN SPECTRUM RECONSTRUCTION

reconstruction of energy spectrum of runaway electrons in nanosecond-pulse discharges in atmospheric air

26th Session of the CIE

作者： Zhang xiaoyan Beijing Polytechnic College Beijing China 100042

＜正＞A dataset of colour spectra can be represented as a linear combination of few principal spectra. The principal components of a spectral dataset are usually generated by the method of Principal Component Analysis（PCA）.The independent Component Analysis（ICA）has been used to abstract the independent components of the spectral dataset by some researchers in recent years and enables data *** this paper,the feature spectra of spectral reflectance of 50 cases Munsell colour cards and 50 cases birch leaves are abstracted by ICA *** reflectance of 150 cases Munsell colour cards and 150 cases birch leaves are reconstructed with the multi-spectral imaging and the algorithm of spectral reconstruction,and with three sets of filters,each compose of two,three,and four filters,and three to fifteen dimensions *** reconstruction results are evaluated by the CLE1976 colour difference and the spectrum reconstruction *** to the results of reconstruction,the relationship between the subspace dimensions,the number of filters and the reconstruction colour differences,spectral error are analyzed in this paper.

关键词： Independent Component Analysis ICA spectrum reconstruction

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Plasma Science and Technology 2021年第6期23卷 89-96页

作者： Jintao QIU Cheng ZHANG Zehui LIU Bangdou HUANG Tao SHAO Beijing International S&T Cooperation Base for Plasma Science and Energy Conversion Institute of Electrical EngineeringChinese Academy of SciencesBeijing 100190People's Republic of China University of Chinese Academy of Sciences Beijing 100049People's Republic of China

This paper presents an experimental investigation into the runaway electron spectrum with a gas diode composed of a rough spherical cathode and plane anode under the excitation of a nanosecond-pulse generator in atmospheric *** runaway electron beams are measured by a collector covered with aluminum foil with a thickness from 0μm(mesh grid)to 50μ*** energy spectrum is calculated by an improved Tikhonov regularization called the maximum entropy *** experimental results show that the transition state of the discharge consisted of multiple streamer channels stretched from the cathode with glow-like plasma uniformly distributed over the *** number of runaway electrons measured by the collector is in the order of 1010 in atmospheric pressure air with a gap spacing of 5 mm and applied voltages of70–130 *** cathode with a rough surface creates a more inhomogeneous electric field and larger emission site for the runaway electrons around the cathode,providing conditions for the coexistence of filamentary streamer and diffuse *** reconstructed spectra show that the energy distribution of the runaway electrons presents a single-peak profile with energies from eU_(m/2)–2 eU_(m/3)(U_(m)is maximal voltage across the gap).

关键词： runaway electrons diffuse discharge nanosecond-pulse discharge spectrum reconstruction