Yang P.,Chengdu University of Technology |
Yan F.,Chengdu University of Technology |
Yang F.,Chengdu University of Technology |
Dong T.,Space Star Technology
IEEE Transactions on Antennas and Propagation | Year: 2016
The techniques of random antenna element distribution and rotation have been proposed to design a low sidelobe and low cross-polarization phased array or reflect array for a long time. In this communication, we demonstrate that the use of randomly rotated (RR) elements can provide random scattering phases and phase center distributions, which can lead to an in-band radar cross section (RCS) reduction for the array. To illustrate the effectiveness of the proposed method, three 8 × 8 circularly polarized (CP) microstrip arrays, 1) the uniform array without rotation; 2) sequentially rotated (SR) array; and 3) RR array, are compared and analyzed. Results indicate that the RCS of the RR array can be reduced significantly, even in the main beam region, while maintaining its high radiation performance. © 2016 IEEE.
Shen Y.,Xidian University |
Xu L.,Xidian University |
Zhang H.,Xidian University |
Chen S.,Space Star Technology |
Song S.,Xidian University
Advances in Space Research | Year: 2015
Relative orbit determination is widely used in the field of autonomously controlled satellite formation flying (SFF). Currently, some traditional techniques cannot meet the strict requirement of the accuracy of relative orbit determination for certain space missions. Thus, the primary purpose of this study is to design some special type of sensor to increase the accuracy of the distance measurement, which can eventually lead to an improvement in the accuracy of relative orbit determination for SFF. Two types of quantum sensors are proposed, based on the double-points quantum ranging (DPQR) and the triangle quantum ranging (TQR) schemes that utilize the second-order correlation between the entangled photons. Simulation result shows that the ranging accuracy of the TQR-type sensor is more precise than that of the DPQR-type one. Additionally, the unscented Kalman filter (UKF) is used to estimate the relative state of the SFF, which uses the TQR-type sensor as the measurement model compared with a traditional sensor. The simulation results show that the quantum sensor is superior to the traditional one and their estimation errors of the position and velocity remain within 1 cm and 1 mm/s, respectively, at a relative distance of 1 km between the chief and deputy satellites. © 2015 COSPAR.Published by Elsevier Ltd. All rights reserved.
Zhong B.,CAS Institute of Remote Sensing |
Zhang Y.,CAS Institute of Remote Sensing |
Du T.,Space Star Technology |
Yang A.,Chongqing University of Posts and Telecommunications |
And 2 more authors.
IEEE Transactions on Geoscience and Remote Sensing | Year: 2014
The charge-coupled device (CCD) is visible to near-infrared imaging sensors onboard the Chinese Huan Jing 1 satellites. Like many sensors, the CCD lack onboard calibration capabilities, so alternative methods are required, e.g., cross-calibration. The wide field of view of the CCD sensors provides challenges for cross-calibration with narrow field of view sensors. We developed a technique to take advantage of a site with a uniform surface material and a natural topographic variation. Due to the topography, near-nadir Landsat Enhanced Thematic Mapper (TM) Plus (ETM +) observations actually see the material at a wide range of illumination and viewing angles. These observations and Advanced Spaceborne Thermal Emission and Reflection Radiometer global digital elevation model data were used to develop a model of this site's bidirectional reflectance distribution function that covered most of the illumination and view angle range of the CCD data. We validated this model by comparing the simulations to actual ETM + and TM surface reflectances. The validated model was then used to calibrate the CCD instruments. The results were consistent to within 5% of field intensive vicarious calibration data. © 1980-2012 IEEE.
Huang P.,Inner Mongolia University of Technology |
Li S.,Space Star Technology |
Xu W.,CAS Institute of Electronics
IEEE Geoscience and Remote Sensing Letters | Year: 2014
The novel displaced phase center antenna (DPCA) azimuth multichannel technique is well suited to improve the coarser azimuth resolution of the terrain observation by progressive scans (TOPS) mode for a fixed total receive antenna length. However, both the azimuth multichannel nonuniform sampling and the aliased Doppler spectrum in TOPS raise the azimuth data processing difficulty. This letter proposes an innovative full-aperture processing approach, which adds an azimuth derotation step for each azimuth channel before azimuth multichannel data reconstruction and utilizes the prefiltering operation in the two-step focusing technique to resolve both azimuth ambiguity problems caused by the DPCA technique and azimuth beam progressive scanning. In addition to presenting the proposed azimuth preprocessing approach, the impact of the approach on the azimuth ambiguity-to-signal ratio is analyzed in detail. Simulation results validate the proposed multichannel processing approach for the TOPS mode. © 2013 IEEE.
Xiangxiang L.,Space Star Technology
ICEIEC 2015 - Proceedings of 2015 IEEE 5th International Conference on Electronics Information and Emergency Communication | Year: 2015
Based on the summarization of the demands on management services of massive remote sensing images data, the status quo at home and abroad are analyzed from the following two aspects: specification demands of data management and storage organizational structure. The advantages and defects of several typical data storage centers are compared with each other, consequently, the key technologies of the management system of massive remote sensing image data in the ground application system is discussed. © 2015 IEEE.