For detecting exoplanets with high precision,using the angular distance between the two stars to detect the periodic motion of the star will be a better choice.This approach can avoid importing the position error of t...For detecting exoplanets with high precision,using the angular distance between the two stars to detect the periodic motion of the star will be a better choice.This approach can avoid importing the position error of the reference catalog in the process that uses a traditional photographic plate to derive the star position suffers.At the precision level of microarcseconds,the error caused by optical axis deviation is not negligible.In this paper,we evaluate the impact of the stability of the optical axis on the relative angular distance measurement from the aspects of theoretical analysis and numerical simulation.When the angular distance error limit of 1 microarcsecond is given,the upper limit of optical axis deviation is estimated to be 68 milliarcsecond.In addition,when limiting the deviation of the optical axis,we give the corresponding error allowance of angular distance measurement.Moreover,we also discuss the way to resolve the problem of CCD distortion and focal length change on the measurement of angular distance.The work in this paper is of guiding significance to the design of a telescope.展开更多
OCC(Optical Camera Communication)has been proposed in recent years as a new technique for visible light communications.This paper introduces the implementation and experimental demonstration of an OCC system.Phase unc...OCC(Optical Camera Communication)has been proposed in recent years as a new technique for visible light communications.This paper introduces the implementation and experimental demonstration of an OCC system.Phase uncertainty and phase slipping caused by camera sampling are the two major challenges for OCC.In this paper,we propose a novel modulation scheme called undersampled differential phase shift on–off keying to encode binary data bits without exhibiting any flicker to human eyes.The phase difference between two consecutive samples conveys one-bit information,which can be decoded by a low-frame-rate camera receiver.Error detection techniques are introduced to enhance the reliability of the system.We present the hardware and software design of the proposed system,which is implemented with a Xilinx FPGA and a Logitech commercial camera.Experimental results demonstrate that a bit-error rate of 10−5 can be achieved with 7.15 mW received signal power over a link distance of 15 cm.展开更多
基金funded by the National Natural Science Foundation of China(NSFC,Grant No.11833004)funded by the Strategic Priority Research Program on Space Science,the Chinese Academy of Sciences,Grant No.XDA15020800。
文摘For detecting exoplanets with high precision,using the angular distance between the two stars to detect the periodic motion of the star will be a better choice.This approach can avoid importing the position error of the reference catalog in the process that uses a traditional photographic plate to derive the star position suffers.At the precision level of microarcseconds,the error caused by optical axis deviation is not negligible.In this paper,we evaluate the impact of the stability of the optical axis on the relative angular distance measurement from the aspects of theoretical analysis and numerical simulation.When the angular distance error limit of 1 microarcsecond is given,the upper limit of optical axis deviation is estimated to be 68 milliarcsecond.In addition,when limiting the deviation of the optical axis,we give the corresponding error allowance of angular distance measurement.Moreover,we also discuss the way to resolve the problem of CCD distortion and focal length change on the measurement of angular distance.The work in this paper is of guiding significance to the design of a telescope.
文摘OCC(Optical Camera Communication)has been proposed in recent years as a new technique for visible light communications.This paper introduces the implementation and experimental demonstration of an OCC system.Phase uncertainty and phase slipping caused by camera sampling are the two major challenges for OCC.In this paper,we propose a novel modulation scheme called undersampled differential phase shift on–off keying to encode binary data bits without exhibiting any flicker to human eyes.The phase difference between two consecutive samples conveys one-bit information,which can be decoded by a low-frame-rate camera receiver.Error detection techniques are introduced to enhance the reliability of the system.We present the hardware and software design of the proposed system,which is implemented with a Xilinx FPGA and a Logitech commercial camera.Experimental results demonstrate that a bit-error rate of 10−5 can be achieved with 7.15 mW received signal power over a link distance of 15 cm.
