Ionospheric scintillation behaves as the random fluctuation of amplitude and phase of the traveling electromagnetic wave caused by irregularities of the Earth ionosphere.In the radio waveband,it influences the perform...Ionospheric scintillation behaves as the random fluctuation of amplitude and phase of the traveling electromagnetic wave caused by irregularities of the Earth ionosphere.In the radio waveband,it influences the performance of satellite navigation systems and radio astronomy observations.Here,the 3.2 m radio telescope located at Sun Yat-sen University(SYSU 3.2 m radio telescope)in Zhuhai is used to observe the radio signal from the geosynchronous Earth orbit satellite C0_(3) of the Beidou navigation system at 1561.098±3 MHz.Fluctuations of intensity in the dynamic spectra,i.e.,the standard deviation S_(4)index,are analyzed to study the scintillation of the ionosphere.The results are compared with those from global navigation satellite system(GNSS)receivers and a GPStation-6 scintillation monitor located at the same place.GNSS receiver and GPStation-6 observations confirm the scintillation events observed by the SYSU 3.2 m radio telescope.The radio telescope observations provide insights into the impact of ionospheric scintillation on astronomical observations.展开更多
Active adjustment technology is used to solve the problem of reduced electrical performance of large reflector antennas caused by environmental factors.This technology is crucial for the operation of antennas under hi...Active adjustment technology is used to solve the problem of reduced electrical performance of large reflector antennas caused by environmental factors.This technology is crucial for the operation of antennas under high-frequency working conditions.This paper proposes a full-path active adjustment strategy for dual-reflector antennas.This strategy takes into account the working mode of the adjustment mechanism under comprehensive influencing factors and achieves the optimal receiving performance at the full elevation by changing different adjustment algorithms.First,the relationship between the displacement of reflector and the wavefront phase was established based on geometric optics.Second,three adjustment algorithms of the double reflector antenna were compared and analyzed:based on the standard,the fit and the optimal parabolic surface,the calculation process of the adjustment amount was derived.An adjustment strategy model for multiple working conditions was proposed by introducing the elevation and the complexity coefficient and combining three adjustment algorithms.Finally,a finite element analysis was conducted on the dual-reflector antenna with a diameter of 110 m,and the advantages and disadvantages of different adjustment algorithms were compared.The results show that strategy model not only achieves the optimal state of the antenna at the full elevation,but also shortens the adjustment amount of the adjustment mechanism and improves the working efficiency of the antenna under various working conditions.展开更多
Accurate estimation of Zenith Tropospheric Delay(ZTD)is essential for mitigating atmospheric effects in radio astronomical observations and improving the retrieval of precipitable water vapor(PWV).In this study,we fir...Accurate estimation of Zenith Tropospheric Delay(ZTD)is essential for mitigating atmospheric effects in radio astronomical observations and improving the retrieval of precipitable water vapor(PWV).In this study,we first analyze the periodic characteristics of ZTD at the NanShan Radio Telescope site using Fourier transform,revealing its dominant seasonal variations,and then investigate the correlation between ZTD and local meteorological parameters,to better understand atmospheric influences on tropospheric delay.Based on these analyses,we propose a hybrid deep learning Gated Recurrent Units-Long Short-Term Memory model,incorporating meteorological parameters as external inputs to enhance ZTD forecasting accuracy.Experimental results demonstrate that the proposed approach achieves a Root Mean Squared Error of 7.97 mm and a correlation coefficient R of 96%,significantly outperforming traditional empirical models and standalone deep learning architectures.These findings indicate that the model effectively captures both short-term dynamics and long-term dependencies in ZTD variations.The improved ZTD predictions not only contribute to reducing atmospheric errors in radio astronomical observations but also provide a more reliable basis for PWV retrieval and forecasting.This study highlights the potential of deep learning in tropospheric delay modeling,offering advancements in both atmospheric science and geodetic applications.展开更多
The radio telescope possesses high sensitivity and strong signal collection capabilities.While receiving celestial radiation signals,it also captures Radio Frequency Interferences(RFIs)introduced by human activities.R...The radio telescope possesses high sensitivity and strong signal collection capabilities.While receiving celestial radiation signals,it also captures Radio Frequency Interferences(RFIs)introduced by human activities.RFI,as signals originating from sources other than the astronomical targets,significantly impacts the quality of astronomical data.This paper presents an RFI fast mitigation algorithm based on block Least Mean Square(LMS)algorithm.It enhances the traditional adaptive LMS filter by grouping L adjacent time-sampled points into one block and applying the same filter coefficients for filtering within each block.This transformation reduces multiplication calculations and enhances algorithm efficiency by leveraging the time-domain convolution theorem.The algorithm is tested using baseband data from the Parkes 64 m radio telescope's pulsar observations and simulated data.The results confirm the algorithm's effectiveness,as the pulsar profile after RFI mitigation closely matches the original pulsar profile.展开更多
The Shanghai Tianma 65 m radio telescope(TMRT)is a large,fully rotatable radio telescope with multiple scientific purposes.The main body of the telescope and four low-frequency receiving systems,including L,C,and S/X ...The Shanghai Tianma 65 m radio telescope(TMRT)is a large,fully rotatable radio telescope with multiple scientific purposes.The main body of the telescope and four low-frequency receiving systems,including L,C,and S/X bands,were completed between 2008 and 2012.From 2013 to 2017,four high-frequency receiving systems,including Ku,K,Ka,and Q bands,were constructed and their performance was comprehensively tested.There are three main innovations.(1)A fully movable large radio telescope system with advanced performance and complete functions has been built.(2)An advanced,reliable main reflector adjustment system has been completed,overcoming gravity deformation and creating a large antenna with a main reflective surface accuracy of 0.28 mm(root mean square)for any elevation.(3)Five innovative technologies have been developed to achieve high-precision pointing in any direction within 3″.The TMRT has made a crucial contribution to the orbital measurement and positioning of China’s lunar and deep space probes.Significantly enhancing China's ability to participate in international VLBI observations and radio astronomy,this has facilitated a series of achievements in observational radio astronomical research,in areas such as VLBI,spectral lines,and pulsars.展开更多
The Tianma 65 m radio telescope(TMRT)at Shanghai is a fully steerable single-dish radio telescope in China,operating at centimeter to millimeter wavelengths(1.25 GHz to 50 GHz).This paper presents details on the main ...The Tianma 65 m radio telescope(TMRT)at Shanghai is a fully steerable single-dish radio telescope in China,operating at centimeter to millimeter wavelengths(1.25 GHz to 50 GHz).This paper presents details on the main specifications,design,performance analysis,testing,and construction of the telescope antenna.The measured total efficiency is better than 50%over the whole elevation angle range,first sidelobe levels are less than−20 dB,antenna system noise temperatures are less than 70 K at 30°elevation angle,and pointing accuracy is less than 3″.The measured and calculated results are in good agreement,verifying the effectiveness of the design and analysis.展开更多
【应用背景】快速射电暴(Fast Radio Burst,FRB)搜寻是500米口径球面射电望远镜(FAST)的重要科学目标之一,其计算复杂度高,数据量大,当前算法GPU利用率偏低,数据处理需较多的人工介入操作。【目的】在不修改算法实现的前提下,实现进程级...【应用背景】快速射电暴(Fast Radio Burst,FRB)搜寻是500米口径球面射电望远镜(FAST)的重要科学目标之一,其计算复杂度高,数据量大,当前算法GPU利用率偏低,数据处理需较多的人工介入操作。【目的】在不修改算法实现的前提下,实现进程级GPU并行优化,提高GPU整体资源利用率,简化算法运行调度,支持利用自动化脚本驱动计算过程。【方法】利用容器化封装FRB搜寻算法,结合GPU聚合技术实现多个FRB搜寻计算容器的多进程并行,支持GPU闲时复用。通过容器化封装屏蔽了GPU调用、依赖库管理等技术细节,减少人工介入操作。【结果】算法实验结果表明,在不修改原始算法、不增加GPU资源的前提下,将单GPU绑定6个计算进程,并行优化可实现FRB搜寻算法的加速比达到5.3,并行效率达到0.88,取得良好的并行效果。【结论】基于容器化封装及进程级GPU聚合的并行优化,可实现GPU利用率及计算效率的提升,有效支持自动化处理。该方法还具有良好的通用性,可适用于类似应用的并行优化。展开更多
基金supported by the National Natural Science Foundation of China(NSFC,Nos.42150105,12273062 and12473095)the CAS-JSPS Joint Research Project(No.178GJHZ2023180MI)+1 种基金the National SKA Program of China(grant No.2022SKA0120101)the China Manned Space Project(No.CMS-CSST-2021-B09 and No.CMS-CSST-2021-B12)。
文摘Ionospheric scintillation behaves as the random fluctuation of amplitude and phase of the traveling electromagnetic wave caused by irregularities of the Earth ionosphere.In the radio waveband,it influences the performance of satellite navigation systems and radio astronomy observations.Here,the 3.2 m radio telescope located at Sun Yat-sen University(SYSU 3.2 m radio telescope)in Zhuhai is used to observe the radio signal from the geosynchronous Earth orbit satellite C0_(3) of the Beidou navigation system at 1561.098±3 MHz.Fluctuations of intensity in the dynamic spectra,i.e.,the standard deviation S_(4)index,are analyzed to study the scintillation of the ionosphere.The results are compared with those from global navigation satellite system(GNSS)receivers and a GPStation-6 scintillation monitor located at the same place.GNSS receiver and GPStation-6 observations confirm the scintillation events observed by the SYSU 3.2 m radio telescope.The radio telescope observations provide insights into the impact of ionospheric scintillation on astronomical observations.
基金funded by the National Natural Science Foundation of China(Nos.12363011,52275270,52275269)Natural Science Foundation of Xinjiang Uygur Autonomous Region(No.2023D01C22)+1 种基金the Tianchi Talents Program of Xinjiang,the National Key Basic Research Program of China(No.2021YFC2203501)the Xinjiang Postdoctoral Foundation.
文摘Active adjustment technology is used to solve the problem of reduced electrical performance of large reflector antennas caused by environmental factors.This technology is crucial for the operation of antennas under high-frequency working conditions.This paper proposes a full-path active adjustment strategy for dual-reflector antennas.This strategy takes into account the working mode of the adjustment mechanism under comprehensive influencing factors and achieves the optimal receiving performance at the full elevation by changing different adjustment algorithms.First,the relationship between the displacement of reflector and the wavefront phase was established based on geometric optics.Second,three adjustment algorithms of the double reflector antenna were compared and analyzed:based on the standard,the fit and the optimal parabolic surface,the calculation process of the adjustment amount was derived.An adjustment strategy model for multiple working conditions was proposed by introducing the elevation and the complexity coefficient and combining three adjustment algorithms.Finally,a finite element analysis was conducted on the dual-reflector antenna with a diameter of 110 m,and the advantages and disadvantages of different adjustment algorithms were compared.The results show that strategy model not only achieves the optimal state of the antenna at the full elevation,but also shortens the adjustment amount of the adjustment mechanism and improves the working efficiency of the antenna under various working conditions.
基金funded by the CAS“Light of West China”Program(grant Nos.2021-XBQNXZ-030 and 2021-XBQNXZ-005)the Xinjiang Key Laboratory of Radio Astrophysics(grant No.2023D04064)the National Key R&D Program of China(grant No.2024YFA1611503)。
文摘Accurate estimation of Zenith Tropospheric Delay(ZTD)is essential for mitigating atmospheric effects in radio astronomical observations and improving the retrieval of precipitable water vapor(PWV).In this study,we first analyze the periodic characteristics of ZTD at the NanShan Radio Telescope site using Fourier transform,revealing its dominant seasonal variations,and then investigate the correlation between ZTD and local meteorological parameters,to better understand atmospheric influences on tropospheric delay.Based on these analyses,we propose a hybrid deep learning Gated Recurrent Units-Long Short-Term Memory model,incorporating meteorological parameters as external inputs to enhance ZTD forecasting accuracy.Experimental results demonstrate that the proposed approach achieves a Root Mean Squared Error of 7.97 mm and a correlation coefficient R of 96%,significantly outperforming traditional empirical models and standalone deep learning architectures.These findings indicate that the model effectively captures both short-term dynamics and long-term dependencies in ZTD variations.The improved ZTD predictions not only contribute to reducing atmospheric errors in radio astronomical observations but also provide a more reliable basis for PWV retrieval and forecasting.This study highlights the potential of deep learning in tropospheric delay modeling,offering advancements in both atmospheric science and geodetic applications.
基金supported by the National Key R&D Program of China(Nos.2021YFC2203502 and 2022YFF0711502)the National Natural Science Foundation of China(NSFC)(12173077 and 12073067)+7 种基金the Tianshan Innovation Team Plan of Xinjiang Uygur Autonomous Region(2022D14020)the Tianshan Talent Project of Xinjiang Uygur Autonomous Region(2022TSYCCX0095)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(grant No.PTYQ2022YZZD01)China National Astronomical Data Center(NADC)the Operation,Maintenance and Upgrading Fund for Astronomical Telescopes and Facility Instruments,budgeted from the Ministry of Finance of China(MOF)and administrated by the Chinese Academy of Sciences(CAS)Natural Science Foundation of Xinjiang Uygur AutonomousRegion(2022D01A360)the CAS“Light of West China”program under No.2022-XBQNXZ-012supported by Astronomical Big Data Joint Research Center,cofounded by National Astronomical Observatories,Chinese Academy of Sciences。
文摘The radio telescope possesses high sensitivity and strong signal collection capabilities.While receiving celestial radiation signals,it also captures Radio Frequency Interferences(RFIs)introduced by human activities.RFI,as signals originating from sources other than the astronomical targets,significantly impacts the quality of astronomical data.This paper presents an RFI fast mitigation algorithm based on block Least Mean Square(LMS)algorithm.It enhances the traditional adaptive LMS filter by grouping L adjacent time-sampled points into one block and applying the same filter coefficients for filtering within each block.This transformation reduces multiplication calculations and enhances algorithm efficiency by leveraging the time-domain convolution theorem.The algorithm is tested using baseband data from the Parkes 64 m radio telescope's pulsar observations and simulated data.The results confirm the algorithm's effectiveness,as the pulsar profile after RFI mitigation closely matches the original pulsar profile.
基金supported by National Natural Science Foundation of China(12273098).
文摘The Shanghai Tianma 65 m radio telescope(TMRT)is a large,fully rotatable radio telescope with multiple scientific purposes.The main body of the telescope and four low-frequency receiving systems,including L,C,and S/X bands,were completed between 2008 and 2012.From 2013 to 2017,four high-frequency receiving systems,including Ku,K,Ka,and Q bands,were constructed and their performance was comprehensively tested.There are three main innovations.(1)A fully movable large radio telescope system with advanced performance and complete functions has been built.(2)An advanced,reliable main reflector adjustment system has been completed,overcoming gravity deformation and creating a large antenna with a main reflective surface accuracy of 0.28 mm(root mean square)for any elevation.(3)Five innovative technologies have been developed to achieve high-precision pointing in any direction within 3″.The TMRT has made a crucial contribution to the orbital measurement and positioning of China’s lunar and deep space probes.Significantly enhancing China's ability to participate in international VLBI observations and radio astronomy,this has facilitated a series of achievements in observational radio astronomical research,in areas such as VLBI,spectral lines,and pulsars.
文摘The Tianma 65 m radio telescope(TMRT)at Shanghai is a fully steerable single-dish radio telescope in China,operating at centimeter to millimeter wavelengths(1.25 GHz to 50 GHz).This paper presents details on the main specifications,design,performance analysis,testing,and construction of the telescope antenna.The measured total efficiency is better than 50%over the whole elevation angle range,first sidelobe levels are less than−20 dB,antenna system noise temperatures are less than 70 K at 30°elevation angle,and pointing accuracy is less than 3″.The measured and calculated results are in good agreement,verifying the effectiveness of the design and analysis.
文摘【应用背景】快速射电暴(Fast Radio Burst,FRB)搜寻是500米口径球面射电望远镜(FAST)的重要科学目标之一,其计算复杂度高,数据量大,当前算法GPU利用率偏低,数据处理需较多的人工介入操作。【目的】在不修改算法实现的前提下,实现进程级GPU并行优化,提高GPU整体资源利用率,简化算法运行调度,支持利用自动化脚本驱动计算过程。【方法】利用容器化封装FRB搜寻算法,结合GPU聚合技术实现多个FRB搜寻计算容器的多进程并行,支持GPU闲时复用。通过容器化封装屏蔽了GPU调用、依赖库管理等技术细节,减少人工介入操作。【结果】算法实验结果表明,在不修改原始算法、不增加GPU资源的前提下,将单GPU绑定6个计算进程,并行优化可实现FRB搜寻算法的加速比达到5.3,并行效率达到0.88,取得良好的并行效果。【结论】基于容器化封装及进程级GPU聚合的并行优化,可实现GPU利用率及计算效率的提升,有效支持自动化处理。该方法还具有良好的通用性,可适用于类似应用的并行优化。
