Micro-vibration is an important factor affecting the imaging quality and pointing accu-racy of the in-orbit satellites.To address the problem of micro-vibration compensation,a general summary for modeling,analysis,sup...Micro-vibration is an important factor affecting the imaging quality and pointing accu-racy of the in-orbit satellites.To address the problem of micro-vibration compensation,a general summary for modeling,analysis,suppression,and compensation approach should be outlined.In this review,micro-vibration characteristics and its impacts on the payloads are firstly analyzed.Afterwards,methods for micro-vibration measurement are provided.In detail,the principles and practical applications of these methods are introduced.Then,advanced technologies for micro-vibration suppression are summarized from micro-vibration source attenuation,transfer path opti-mization and sensitive load isolation.Two approaches have been found to be effective for micro-vibration compensation.The one is the Line-of-Sight(LOS)stabilization assisted with Inertial Ref-erence Unit(IRU).The other is using image restoration technology to remove the blur caused by platform jitter.The compensation technique and research status of the two techniques are reviewed.This work will provide researchers with technical guidelines for micro-vibration suppression.展开更多
Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose spac...Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose space power is limited due to the small size of satellite. The pilot channel of CDMA technology is very important for earth mobile station(EMS) in LEO system to recover carrier and code, but the power requirement of pilot channel is very higher than that of other channels. In this paper, a power reduction method for pilot channel is proposed. By the new method, the power of pilot channel transmitted from LEO satellite is reduced to a lower level. For improving the signal to noise ratio(SNR) of pilot channel with lower power, coherent integration is employed in EMS at the pre-processing stage. Considering the high dynamic situation of LEO satellite, the long period of time for integration will deteriorate the receiving performance of EMS, therefore, a dynamic compensation module is added to carrier tracking loop against the high dynamic. Meanwhile, the transfer function of the new tracking loop and the condition for steadystate zero error are deduced. Numerical examples are provided to demonstrate effectiveness of the proposed approach.展开更多
The High Intensity Gamma-ray Source（HIGS） at Duke University is an accelerator-driven Compton gamma-ray source, providing high flux gamma-ray beam from 1 MeV to 100 MeV for photo-nuclear physics research.The HIGS fa...The High Intensity Gamma-ray Source（HIGS） at Duke University is an accelerator-driven Compton gamma-ray source, providing high flux gamma-ray beam from 1 MeV to 100 MeV for photo-nuclear physics research.The HIGS facility operates three accelerators, a linac pre-injector（0.16 GeV）, a booster injector（0.16—1.2 GeV）,and an electron storage ring（0.24—1.2 GeV）. Because of the proximity of the booster injector to the storage ring, the magnetic field of the booster dipoles close to the ring can significantly alter the closed orbit in the storage ring being operated in the low energy region. This type of orbit distortion can be a problem for certain precision experiments which demand a high degree of energy consistency of the gamma-ray beam. This energy consistency can be achieved by maintaining consistent aiming of the gamma-ray beam, and therefore a steady electron beam orbit and angle at the Compton collision point. To overcome the booster leakage field problem, we have developed an orbit compensation scheme. This scheme is developed using two fast orbit correctors and implemented as a feedforward which is operated transparently together with the slow orbit feedback system. In this paper, we will describe the development of this leakage field compensation scheme, and report the measurement results, which demonstrate the effectiveness of the scheme.展开更多
基金supported by the National Natural Science Foundation of China (No.62203322)the China Postdoctoral Science Foundation (No.2022M712372)the Enlisting and Leading Program of the Taihu Laboratory of Deepsea Technological Science,China (No.2022JBGS03001).
文摘Micro-vibration is an important factor affecting the imaging quality and pointing accu-racy of the in-orbit satellites.To address the problem of micro-vibration compensation,a general summary for modeling,analysis,suppression,and compensation approach should be outlined.In this review,micro-vibration characteristics and its impacts on the payloads are firstly analyzed.Afterwards,methods for micro-vibration measurement are provided.In detail,the principles and practical applications of these methods are introduced.Then,advanced technologies for micro-vibration suppression are summarized from micro-vibration source attenuation,transfer path opti-mization and sensitive load isolation.Two approaches have been found to be effective for micro-vibration compensation.The one is the Line-of-Sight(LOS)stabilization assisted with Inertial Ref-erence Unit(IRU).The other is using image restoration technology to remove the blur caused by platform jitter.The compensation technique and research status of the two techniques are reviewed.This work will provide researchers with technical guidelines for micro-vibration suppression.
基金supported by the National High Technology Research and Development Program of China (863 Program) (No.2012AA01A502)the National Natural Science Foundation of China (No.61179006)the Science and Technology Support Program of Sichuan Province (No.2014GZX0004)
文摘Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose space power is limited due to the small size of satellite. The pilot channel of CDMA technology is very important for earth mobile station(EMS) in LEO system to recover carrier and code, but the power requirement of pilot channel is very higher than that of other channels. In this paper, a power reduction method for pilot channel is proposed. By the new method, the power of pilot channel transmitted from LEO satellite is reduced to a lower level. For improving the signal to noise ratio(SNR) of pilot channel with lower power, coherent integration is employed in EMS at the pre-processing stage. Considering the high dynamic situation of LEO satellite, the long period of time for integration will deteriorate the receiving performance of EMS, therefore, a dynamic compensation module is added to carrier tracking loop against the high dynamic. Meanwhile, the transfer function of the new tracking loop and the condition for steadystate zero error are deduced. Numerical examples are provided to demonstrate effectiveness of the proposed approach.
基金Supported by National Natural Science Foundation of China(11175180,11475167)US DOE(DE-FG02-97ER41033)
文摘The High Intensity Gamma-ray Source（HIGS） at Duke University is an accelerator-driven Compton gamma-ray source, providing high flux gamma-ray beam from 1 MeV to 100 MeV for photo-nuclear physics research.The HIGS facility operates three accelerators, a linac pre-injector（0.16 GeV）, a booster injector（0.16—1.2 GeV）,and an electron storage ring（0.24—1.2 GeV）. Because of the proximity of the booster injector to the storage ring, the magnetic field of the booster dipoles close to the ring can significantly alter the closed orbit in the storage ring being operated in the low energy region. This type of orbit distortion can be a problem for certain precision experiments which demand a high degree of energy consistency of the gamma-ray beam. This energy consistency can be achieved by maintaining consistent aiming of the gamma-ray beam, and therefore a steady electron beam orbit and angle at the Compton collision point. To overcome the booster leakage field problem, we have developed an orbit compensation scheme. This scheme is developed using two fast orbit correctors and implemented as a feedforward which is operated transparently together with the slow orbit feedback system. In this paper, we will describe the development of this leakage field compensation scheme, and report the measurement results, which demonstrate the effectiveness of the scheme.
