This paper proposes a space false alarm target detection method based on star information. The central idea is that if a non-star target coincides with the same projected star for several consecutive frames, it is considered as a false alarm target. The implementation steps are: First, project the stars in the star catalog to the image plane. The ID numbers of stars in the star catalog is placed in the data structure of projected star points. Second, based on the matching results of the projected star points and the image points, the image points matching with the stars is obtained, and the non-star target is identified. Third, compare the non-star target with the matching points in each frame. If the Euclidean distance is less than a certain threshold, then the non-star target will be added to the predetermined false alarm target queue. The ID number is placed in the predetermined false alarm target data structure. Fourth, if the ID number of the predetermined false alarm target is the same in several consecutive frames, the target will be regarded as a confirmed false alarm target, and it will be removed from the non-star target queue. Simulations show that the method can effectively realize the identification and elimination of false alarm targets and reduce the false alarm rate.
Aiming at the problem that the background of deep space is complex and changeable, and the exposure time of CMOS image sensor is limited, the image is overexposed or too dark, an automatic gain adjustment algorithm of CMOS sensor based on image features is proposed. Starting from the characteristics of the sensor itself, the algorithm automatically adjusts the digital gain of the CMOS sensor to adapt to the change of the incident light intensity according to the difference of the captured images, improves the dynamic range of the image, and makes up for the limited exposure time range. Through experiments on specific imaging systems, the algorithm compares the imaging effects before and after using the algorithm, and it is concluded that the algorithm is versatile and easy to implement and can achieve good imaging results in scenes with drastic changes in illumination.
A certain model should be used to predict and track the space objects that may affect the operation of satellites. In this paper, the Two-Line Elements (TLE) and the Simplified General Perturbations 4 (SGP4) models are used to calculate the position and velocity vectors of satellite A/B in the True Equator Mean Equinox (TEME) coordinate system and the Earth-Centered Inertial (ECI) system. Satellite A is selected as the observation platform to carry the camera, and the imaging positions of target satellite B on the camera of satellite A in the TEME and ECI coordinate systems are calculated respectively. The imaging trajectories are superimposed to generate several turns. The difference between the imaging positions in TEME and ECI coordinate systems is calculated, and the influence of the Earth's precession and nutation on the imaging trajectory is analyzed.
KEYWORDS: Digital signal processing, Field programmable gate arrays, Computer programming, Inspection, Reliability, Switches, Signal processing, Switching, Space operations, Reconstruction algorithms
The FPGA+DSP architecture has been widely used in spaceborne digital signal systems. In order to adapt to the complex space environment, reduce the impact of single-event flipping, and meet the on-orbit requirements of intelligence and high reliability, a spaceborne dual-core system is proposed. On-track betting method. Taking Fudan Micro JFM7 series JFM7K325T and TI's TMS320C6678 as examples, the hardware circuit design and software design of FPGA+DSP program on-rail injection are introduced in detail. The ground experiment verification proves that the on-rail injection method is reasonable and feasible, and improves the reliability of the system that can complete the remote fault repair and function expansion of the onboard software.
KEYWORDS: Cameras, Sensors, Field programmable gate arrays, Video, Imaging systems, Data processing, Clocks, Data conversion, Human-machine interfaces, Data acquisition
To obtain the high-resolution and real-time digital image of the monitoring target and meet the requirements of miniaturization, a light and high-resolution video camera system based on FPGA is designed. The camera uses the large array CMOS sensor CMV12000 produced by the CMOSIS company and transfers the output data to the computer through Camlink interface. By using the FPGA as the core of timing control and completing the design of time-driving of CMOS sensor, output data remapping and Camlink interface with Verilog hardware language, the design of the camera is realized and a imaging experiment is carried out. The result shows that the driving sequence of the camera is reasonable and the communication with computer is correct. The camera operates stably and takes high quality images with the image resolution is 4096×3072.
The camera mounted on the satellite two-dimensional tracking platform takes images of the star background, and using the star map recognition method based on triangle matching can eliminate stars and extract non-stellar targets. When the tracking platform is used to track the non-stellar targets and is moving fast, the tracking targets will be lost. To solve this problem, a spatial target tracking method based on stellar background is proposed in this paper. Firstly, the rotation matrix of the camera in the geocentric equatorial inertial coordinate system at the moment of two consecutive image frames is calculated based on triangle matching, and targets of each image frame are extracted. For a certain target, the coordinate position corresponding to the target are calculated based on the transformation of the rotation matrix. And then the motion of the target in the inertial coordinate system is superimposed to derive the predicted coordinate position of the target. Finally, the nearest Euclidean distance from the predicted coordinates is found among the current target points. If the Euclidean distance is less than a certain threshold value, the target tracking is successful. The simulation experiment shows that when the tracking platform is moving fast, the target can be tracked continuously and stably.
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