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A comprehensive error calibration method based on dual uniform circular array Research Article

Jia-jia Zhang, Hui Chen, Song Xiao, Meng-yu Ni,zjj2015wuhan@163.com

Frontiers of Information Technology & Electronic Engineering 2019, Volume 20, Issue 10,   Pages 1415-1428 doi: 10.1631/FITEE.1800240

Abstract: Based on the , a novel method is proposed to estimate the direction-of-arrival (DOA) and jointly calibrate , , and . In this paper, only one auxiliary source is required to generate three time-disjoint sources with the help of the rotation platform. Subsequently, according to the principle that the signal subspace is orthogonal to the noise subspace, the cost function is constructed. The alternating iteration method is used to estimate the coefficients of the three kinds of errors. During the process, the proposed algorithm makes full use of the structural characteristics of the array when estimating , while the signal phase matrix is used to eliminate the phase influence caused by the delay in signal arrival at the antenna array when estimating and . Compared with the algorithm using multidimensional nonlinear search, the proposed algorithm has lower computational complexity. Moreover, our algorithm does not require additional auxiliary sensors. Simulation results demonstrate that the proposed algorithm is effective and can precisely and comprehensively calibrate the errors in a .

Keywords： 双圈均匀圆阵；幅相误差；位置误差；互耦误差；校正    

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Research on HJ-1A/B satellites data automatic geometric precision correction design

Xiong Wencheng,Shen Wenming,Wang Qiao,Shi Yuanli,Xiao Rulin and Fu Zhuo

Strategic Study of CAE 2014, Volume 16, Issue 3,   Pages 37-42

Abstract:

HJ-1A/B satellites were developed independently by China，have operated well on-orbit for five years and acquired a large number of high-quality observation data. The realization of the observation data geometric precision correction is of great significance for macro and dynamic ecological environment monitoring. The paper analyzed the parameter characteristics of HJ-1satellite and geometric features of HJ-1satellite level2data（systematic geo-corrected data）. Based on this，the overall HJ-1multi- sensor geometric correction flow and charge-coupled device（CCD）automatic geometric precision correction method were designed.Actual operating data showed that the method could achieve good result for automatic geometric precision correction of HJ-1satellite data，automatic HJ-1CCD image geometric precision correction accuracy could be achieved within two pixels and automatic matching accuracy between the images of same satellite could be obtained less than one pixel.

Keywords： HJ-1satellite     automatic     geometric precision correction     CCD    

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Research and Development of Highly Immersive Multi-projection Virtual Environment Systems

Jia Qingxuan,Xong Jingzhou,Sun Hanxu,Gao Xin,Yao Fusheng

Strategic Study of CAE 2006, Volume 8, Issue 8,   Pages 33-38

Abstract:

This paper presents a framework for a highly immersive multi-projection virtual environment system, and addresses the key problems for building the system such as stereo display., graphics partition, render synchronization, geometric calibration, color calibration, etc. . Using networked PCs, low cost projectors and low capability network equipment, a five-channel 220 degree view field multi-projection virtual environment application system is built. Its coherent and highly immersive display effect validates the method.

Keywords： multi-projection     render synchronization     stereo display     geometric calibration     color calibration    

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HY-2A satellite radar altimeter error correction algorithm and verification

Zhang Youguan,Jia Yongjun,Fan Chenqing,Zhang Jie and Lin Mingsen

Strategic Study of CAE 2013, Volume 15, Issue 7,   Pages 53-61

Abstract:

There are many factors affecting the height accuracy of satillite radar altimeter. The dry troposphere delays, wet troposphere delays, invert barometer delays, ionosphere delays, and sea state bias influence the computational accuracy directly. The error correction algorithms for the HY-2A satellite radar altimeter were conducted in this research. And, these algorithms were vertified using the more mature foreign satellite data such as Jason-1/2 and T/P. The results show that the HY-2A error correction algorithms can meet the accuracy requirements.

Keywords： altimeter error correction     HY-2A satellite radar altimeter    

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High efficiency spreading spectrum modulation based on double orthogonal complex sequences

Shi Xiaohong

Strategic Study of CAE 2012, Volume 14, Issue 3,   Pages 108-112

Abstract:

This paper presents a kind of high efficiency spreading spectrum modulation scheme using double orthogonal complex sequences (DoCS). In this scheme, input data bit-stream is split into many groups with length M. Each group is then mapped into a word of width M and then utilized to select one sequence from 2M-2 DoCS sequences each with length L. After that, the selected sequence is modulated on carrier in QPSK(quadrature phase shift keying) mode. In addition, a novel method named forward phase correction (FPC) is put forward for carrier recovery.

Keywords： modulation and demodulation     high efficiency spreading spectrum modulation     forward phase correction     double orthogonal complex sequences    

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Dual-Comb Ranging Review

Zebin Zhu, Guanhao Wu

Engineering 2018, Volume 4, Issue 6,   Pages 772-778 doi: 10.1016/j.eng.2018.10.002

Abstract:

Absolute distance measurement is a fundamental technique in mobile and large-scale dimensional metrology. Dual-comb ranging is emerging as a powerful tool that exploits phase resolution and frequency accuracy for high-precision and fast-rate distance measurement. Using two coherent frequency combs, dual-comb ranging allows time and phase response to be measured rapidly. It breaks through the limitations related to the responsive bandwidth, ambiguity range, and dynamic measurement characteristics of conventional ranging tools. This review introduces dual-comb ranging and summarizes the key techniques for realizing this ranging tool. As optical frequency comb technology progresses, dualcomb ranging shows promise for various professional applications.

Keywords： Ranging     Dual-comb interferometer     Phase noise     Timing jitter     Tight-locking     Post-correction    

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A performance analysis of multi-satellite joint geolocation Article

Ding WANG,Shuai WEI,Ying WU

Frontiers of Information Technology & Electronic Engineering 2016, Volume 17, Issue 12,   Pages 1360-1387 doi: 10.1631/FITEE.1500285

Abstract: Determining the position of an emitter on Earth by using a satellite cluster has many important applications, such as in navigation, surveillance, and remote sensing. However, in realistic situations, a number of factors, such as errors in the meas-urement of signal parameters, uncertainties regarding the position of satellites, and errors in the location of calibration sources, are known to degrade the accuracy of target localization in satellite geolocation systems. We systematically analyze the performance of multi-satellite joint geolocation based on time difference of arrival (TDOA) measurements. The theoretical analysis starts with Cramér–Rao bound (CRB) derivations for four localization scenarios under an altitude constraint and Gaussian noise assumption. In scenario 1, only the TDOA measurement errors of the emitting source are considered and the satellite positions are assumed to be perfectly estimated. In scenario 2, both the TDOA measurement errors and satellite position uncertainties are taken into account. Scenario 3 assumes that some calibration sources with accurate position information are used to mitigate the influence of satellite position perturbations. In scenario 4, several calibration sources at inaccurate locations are used to alleviate satellite position errors in target localization. Through comparing the CRBs of the four localization scenarios, some valuable’s insights are gained into the effects of various error sources on the estimation performance. Two kinds of location mean-square errors (MSE) expressions under the altitude constraint are derived through first-order perturbation analysis and the Lagrange method. The first location MSE provides the theoretical prediction when an estimator assumes that the satellite locations are accurate but in fact have errors. The second location MSE provides the localization accuracy if an estimator assumes that the known calibration source locations are precise while in fact erroneous. Simulation results are included to verify the theoretical analysis.

Keywords： Satellite geolocation     Time difference of arrival (TDOA)     Cramer-Rao bound (CRB)     Calibration sources     Performance analysis    

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In-orbit calibration and validation of atmospheric correction microwave radiometer on HY-2A satellite

Wang Zhenzhan,Zhang Dehai,Zhao Jin and Li Yun

Strategic Study of CAE 2013, Volume 15, Issue 7,   Pages 44-52

Abstract:

Atmospheric correction microwave radiometer (ACMR) is one of the main payloads for correcting atmospheric path delay of radar altimeter on HY-2A satellite. After discussion and analysis on thermal vacuum calibration method of ACMR, microwave transfer functions and related coefficients were given, especially nonlinear coefficients derived from the test for correcting nonlinear responds between the input of antenna temperature and the output of voltage at each channel of ACMR. Meanwhile, antenna pattern correction algorithms for removing the effects of side-lobe and cross-polarization were derived and their coefficients were used for in-orbit data processing. The calibrated antenna temperatures were compared with the similar space-borne microwave radiometer on Jason-1 and Jason-2 satellite (JMR), launched by the NASA-French Space Agency Ocean Surface Topography Mission. The results of comparison showed that the data from ACMR were well matched to those from Jason-1 and Jason-2.

Keywords： HY-2A     ACMR     calibration and validation    

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Correction of Left Ventricular Doppler Echocardiographic Measurements for Physiological Variances Using a Novel Optimized Multivariable Allometric Model in Healthy Chinese Han Adults Article

Guihua Yao, Xiangyun Chen, Wenjing Yang, Qing Zhang, Jing Liu, Huan Liang, Hui Sun, Yao Xu, Li Wang, Jinfeng Xu, Cheng Zhang, Fengrong Sun, Mei Zhang, Xueying Zeng, Yun Zhang

Engineering 2022, Volume 16, Issue 9,   Pages 115-122 doi: 10.1016/j.eng.2021.05.007

Abstract:

Most left ventricular (LV) Doppler measurements vary significantly with age and gender, making it necessary to correct them for physiological variances. We aimed to verify the hypothesis that different Doppler measurements correlate nonlinearly with different biometric variables raised to different scaling factors and exponents. In this work, a total of 23 LV Doppler parameters were measured in 1224 healthy Chinese adults. An optimized multivariable allometric model (OMAM) and scaling equations were developed in 70% of the subjects (group A), and the reliability of the model and equations was verified using the remaining 30% of the subjects (group B) as well as 183 overweight subjects (group C). The single-variable isometric model (SVIM) with body surface area (BSA) as a scaling variable was used for comparison. Before correction, all 23 LV Doppler parameters correlated significantly with one or more of the biometric variables. In group B, gender differences were found in 47.8% (11/23) of the parameters and were eliminated in 81.8% (9/11) of the parameters after correction with OMAM. The successful correction rate with OMAM was 100% (23/23) in group B and 82.6% (19/23) in group C. New reference values for corrected Doppler measurements independent of biometric variables were established. The SVIM with BSA successfully corrected none of the 23 parameters. In conclusion, different LV Doppler parameters allometrically correlated with one or more of the biometric variables. The novel OMAM developed in this study successfully corrected the effects of the physiological variances of most biometric variables on Doppler measurements in healthy and overweight subjects, and was found to be far superior to the SVIM. However, whether the OMAM equations can be applied to other ethnicities, obese subjects, and pathological conditions requires further investigation.

Keywords： Doppler echocardiography     Physiological variance     Allometric model     Normal reference values    

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Title Author Date Type Operation

A comprehensive error calibration method based on dual uniform circular array

Jia-jia Zhang, Hui Chen, Song Xiao, Meng-yu Ni,zjj2015wuhan@163.com

Journal Article

Research on HJ-1A/B satellites data automatic geometric precision correction design

Xiong Wencheng,Shen Wenming,Wang Qiao,Shi Yuanli,Xiao Rulin and Fu Zhuo

Journal Article

Research and Development of Highly Immersive Multi-projection Virtual Environment Systems

Jia Qingxuan,Xong Jingzhou,Sun Hanxu,Gao Xin,Yao Fusheng

Journal Article

HY-2A satellite radar altimeter error correction algorithm and verification

Zhang Youguan,Jia Yongjun,Fan Chenqing,Zhang Jie and Lin Mingsen

Journal Article

High efficiency spreading spectrum modulation based on double orthogonal complex sequences

Shi Xiaohong

Journal Article

Dual-Comb Ranging

Zebin Zhu, Guanhao Wu

Journal Article

A performance analysis of multi-satellite joint geolocation

Ding WANG,Shuai WEI,Ying WU

Journal Article

In-orbit calibration and validation of atmospheric correction microwave radiometer on HY-2A satellite

Wang Zhenzhan,Zhang Dehai,Zhao Jin and Li Yun

Journal Article

Correction of Left Ventricular Doppler Echocardiographic Measurements for Physiological Variances Using a Novel Optimized Multivariable Allometric Model in Healthy Chinese Han Adults

Guihua Yao, Xiangyun Chen, Wenjing Yang, Qing Zhang, Jing Liu, Huan Liang, Hui Sun, Yao Xu, Li Wang, Jinfeng Xu, Cheng Zhang, Fengrong Sun, Mei Zhang, Xueying Zeng, Yun Zhang

Journal Article