The establishment of crop yield estimating model based on microwave and optical satellite images can conduct the mutual verification of the accuracy of the reported crop yield and the precision of the estimating model...The establishment of crop yield estimating model based on microwave and optical satellite images can conduct the mutual verification of the accuracy of the reported crop yield and the precision of the estimating model. With Shou County and Huaiyuan County of Anhui Province as the experimental fields of winter wheat producing areas, the linear winter wheat yield estimating models were established by adopting backscattering coefficient and Normalized Difference Vegetation Index（NDVI） based on images from the synthetic aperture radar（SAR）—RDARSAT-2 and HJ satellite photographed in mid-April and early May, 2014, and then comparisons were conducted on the accuracy of the yield estimating models. The accuracies of the yield estimating models established using co-polarized（HH） and cross-polarized（HV） modes of SAR in Jiangou Town, Shou County were 68.37% and 74.01%, respectively, while the accuracies in Longkang Town, Huaiyuan County were 63.10%and 69.10%, respectively. Accuracies of yield estimating models established by HJ satellite data were 69.52% and 66.43% in Shou County and Huaiyuan County, respectively. Accuracies of winter yield estimating model based on HJ satellite data and that based on SAR were closed, and the yield difference of winter wheat in the lodging region was analyzed in detail. The model results laid the foundation and accumulated experience for the verification, parameters correction and promotion of the winter wheat yield estimating model.展开更多
This letter proposes a method for designing a specific formation of satellites where the flying motion only exists in a circle orbit plane of the reference satellite, which means that the orbit eccentricity is zero. T...This letter proposes a method for designing a specific formation of satellites where the flying motion only exists in a circle orbit plane of the reference satellite, which means that the orbit eccentricity is zero. This method combines the Hill equation, the Kepler equation, and the geometrical inea^ing of orbit elements. It creates the redundancy condition to simplify the deducing process, utilizes multiple conditions to solve the orbit elements for the satellite formation, and obtains the analytical relationship of the orbit elements for the formation satellites with the formation parameters and the orbit elements of the reference satellite. Using these formulations, the orbit elements and formation parameters for the formation satellites can be solved for the given orbit elements of the reference satellite. The letter describes the proposed double-ellipse formation for both GMTI and InSAR, and the validity of the formation is demonstrated via simulation.展开更多
Three-dimensional(3D) synthetic aperture radar(SAR)extends the conventional 2D images into 3D features by several acquisitions in different aspects. Compared with 3D techniques via multiple observations in elevation, ...Three-dimensional(3D) synthetic aperture radar(SAR)extends the conventional 2D images into 3D features by several acquisitions in different aspects. Compared with 3D techniques via multiple observations in elevation, e.g. SAR interferometry(InSAR) and SAR tomography(TomoSAR), holographic SAR can retrieve 3D structure by observations in azimuth. This paper focuses on designing a novel type of orbit to achieve SAR regional all-azimuth observation(AAO) for embedded targets detection and holographic 3D reconstruction. The ground tracks of the AAO orbit separate the earth surface into grids. Target in these grids can be accessed with an azimuth angle span of360°, which is similar to the flight path of airborne circular SAR(CSAR). Inspired from the successive coverage orbits of optical sensors, several optimizations are made in the proposed method to ensure favorable grazing angles, the performance of 3D reconstruction, and long-term supervision for SAR sensors. Simulation experiments show the regional AAO can be completed within five hours. In addition, a second AAO of the same area can be duplicated in two days. Finally, an airborne SAR data process result is presented to illustrate the significance of AAO in 3D reconstruction.展开更多
Formation flying orbit design is one of the key technologies for system design and performance analysis of the distributed SAR satellites. The approximately analytic solution of the passive stable formation flying orb...Formation flying orbit design is one of the key technologies for system design and performance analysis of the distributed SAR satellites. The approximately analytic solution of the passive stable formation flying orbit elements is explored based on the expansion form of Kepler's equation. A new method of orbital parameters design for three-dimensional formation flying SAR satellites is presented, and the precision of the orbital elements is analyzed. Formation flying orbit elements are calculated for the L-Band distributed SAR satellites using the formulas deduced in this paper. The accuracy of the orbital elements is validated by the computer simulation results presented in this paper.展开更多
In this paper,in order to improve the accuracy of the Synthetic Aperture Radar (SAR) satellite attitude using Global Positioning System (GPS) wide-band carrier phase,the SAR satellite attitude kinematic vector and Kal...In this paper,in order to improve the accuracy of the Synthetic Aperture Radar (SAR) satellite attitude using Global Positioning System (GPS) wide-band carrier phase,the SAR satellite attitude kinematic vector and Kalman filter are introduced.Introducing the state variable function of GPS attitude determination algorithm in SAR satellite by means of kinematic vector and describing the observation function by the GPS wide-band carrier phase,the paper uses the Kalman filter algorithm to obtian the attitude variables of SAR satellite.Compared the simulation results of Kalman filter algorithm with the least square algorithm and explicit solution,it is indicated that the Kalman filter algorithm is the best.展开更多
Cluster Synthetic Aperture Radar (SAR) system is composed of a group of spaceborne SAR systems. With its agility of combination, this system can work in several different modes. In this letter, the basic configuration...Cluster Synthetic Aperture Radar (SAR) system is composed of a group of spaceborne SAR systems. With its agility of combination, this system can work in several different modes. In this letter, the basic configuration and the working mode of the system are presented.The special performance of the system compared with the conventional SAR system is indicated.展开更多
基金Supported by the National Natural Science Foundation of China(41205126)the Discipline Construction and Macroscopic Agricultural Research Project of Anhui Academy of Agricultural Sciences(13A1424)+2 种基金the Fund for Youth Innovation of Anhui Academy of Agricultural Sciences(14B1460)the Innovative Research Team for Agricultural Disaster Risk Analysis in Anhui ProvinceAnhui Academy of Agricultural Sciences(14C1409)~~
文摘The establishment of crop yield estimating model based on microwave and optical satellite images can conduct the mutual verification of the accuracy of the reported crop yield and the precision of the estimating model. With Shou County and Huaiyuan County of Anhui Province as the experimental fields of winter wheat producing areas, the linear winter wheat yield estimating models were established by adopting backscattering coefficient and Normalized Difference Vegetation Index（NDVI） based on images from the synthetic aperture radar（SAR）—RDARSAT-2 and HJ satellite photographed in mid-April and early May, 2014, and then comparisons were conducted on the accuracy of the yield estimating models. The accuracies of the yield estimating models established using co-polarized（HH） and cross-polarized（HV） modes of SAR in Jiangou Town, Shou County were 68.37% and 74.01%, respectively, while the accuracies in Longkang Town, Huaiyuan County were 63.10%and 69.10%, respectively. Accuracies of yield estimating models established by HJ satellite data were 69.52% and 66.43% in Shou County and Huaiyuan County, respectively. Accuracies of winter yield estimating model based on HJ satellite data and that based on SAR were closed, and the yield difference of winter wheat in the lodging region was analyzed in detail. The model results laid the foundation and accumulated experience for the verification, parameters correction and promotion of the winter wheat yield estimating model.
文摘This letter proposes a method for designing a specific formation of satellites where the flying motion only exists in a circle orbit plane of the reference satellite, which means that the orbit eccentricity is zero. This method combines the Hill equation, the Kepler equation, and the geometrical inea^ing of orbit elements. It creates the redundancy condition to simplify the deducing process, utilizes multiple conditions to solve the orbit elements for the satellite formation, and obtains the analytical relationship of the orbit elements for the formation satellites with the formation parameters and the orbit elements of the reference satellite. Using these formulations, the orbit elements and formation parameters for the formation satellites can be solved for the given orbit elements of the reference satellite. The letter describes the proposed double-ellipse formation for both GMTI and InSAR, and the validity of the formation is demonstrated via simulation.
基金supported by the National Natural Science Foundation of China (62001436)the Natural Science Foundation of Jiangsu Province under (BK 20190143,JSGG20190823094603691)。
文摘Three-dimensional(3D) synthetic aperture radar(SAR)extends the conventional 2D images into 3D features by several acquisitions in different aspects. Compared with 3D techniques via multiple observations in elevation, e.g. SAR interferometry(InSAR) and SAR tomography(TomoSAR), holographic SAR can retrieve 3D structure by observations in azimuth. This paper focuses on designing a novel type of orbit to achieve SAR regional all-azimuth observation(AAO) for embedded targets detection and holographic 3D reconstruction. The ground tracks of the AAO orbit separate the earth surface into grids. Target in these grids can be accessed with an azimuth angle span of360°, which is similar to the flight path of airborne circular SAR(CSAR). Inspired from the successive coverage orbits of optical sensors, several optimizations are made in the proposed method to ensure favorable grazing angles, the performance of 3D reconstruction, and long-term supervision for SAR sensors. Simulation experiments show the regional AAO can be completed within five hours. In addition, a second AAO of the same area can be duplicated in two days. Finally, an airborne SAR data process result is presented to illustrate the significance of AAO in 3D reconstruction.
文摘Formation flying orbit design is one of the key technologies for system design and performance analysis of the distributed SAR satellites. The approximately analytic solution of the passive stable formation flying orbit elements is explored based on the expansion form of Kepler's equation. A new method of orbital parameters design for three-dimensional formation flying SAR satellites is presented, and the precision of the orbital elements is analyzed. Formation flying orbit elements are calculated for the L-Band distributed SAR satellites using the formulas deduced in this paper. The accuracy of the orbital elements is validated by the computer simulation results presented in this paper.
基金Supported by the Alarming System Used in Supervising Geological Disaster of Chongqing Economic Committee(No.042YZDZ109).
文摘In this paper,in order to improve the accuracy of the Synthetic Aperture Radar (SAR) satellite attitude using Global Positioning System (GPS) wide-band carrier phase,the SAR satellite attitude kinematic vector and Kalman filter are introduced.Introducing the state variable function of GPS attitude determination algorithm in SAR satellite by means of kinematic vector and describing the observation function by the GPS wide-band carrier phase,the paper uses the Kalman filter algorithm to obtian the attitude variables of SAR satellite.Compared the simulation results of Kalman filter algorithm with the least square algorithm and explicit solution,it is indicated that the Kalman filter algorithm is the best.
基金Supported by the university doctorate special research fund (No.20030614001)
文摘Cluster Synthetic Aperture Radar (SAR) system is composed of a group of spaceborne SAR systems. With its agility of combination, this system can work in several different modes. In this letter, the basic configuration and the working mode of the system are presented.The special performance of the system compared with the conventional SAR system is indicated.
