Subjects: Astronomy >> Astrophysical processes submitted time 2023-12-06 Cooperative journals: 《天文研究与技术》
Abstract： Solar eruptions are important manifestations of solar activity, including solar flares and coronal mass ejections (CMEs). They can potentially impact satellite communications and navigation systems, ground power grid systems, and the human living environment. Monitoring and studying solar radio bursts not only enable the prediction of space weather but also serve as a research tool in solar physics. This article introduces a dual-channel high-speed solar radio frequency spectrum observation system designed and developed based on the LabVIEW platform. It aims to monitor solar radio bursts, which are characterized by their randomness, short duration, and rapid changes. The system utilizes a high-speed signal acquisition card with a sampling rate of 1.5GS/s, providing a time resolution of up to 4ms and a frequency resolution of 45.7764 kHz. The acquired signals are processed through FFT power spectrum analysis and displayed as frequency spectra and waterfall plots. The system extracts information such as the frequency, intensity, and duration of solar radio bursts. The observed data is uploaded to a server using the FTP file transfer protocol, optimizing storage resources and facilitating data sharing. This integrated system is specifically applied to analyze signals in the frequency range from 70 MHz to 700 MHz output by the 11-meter solar radio telescope at Chengjiang Fuxian Lake Observatory.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-11-17 Cooperative journals: 《天文研究与技术》
Abstract： In order to complete the monitor of ultra-broadband spectrum for solar radio burst，Yunnan Observatories have designed and developed 4 solar radio spectrometers with the frequency range of 15-80 MHz，100-750 MHz，600-4 200 MHz and 4-15 GHz，which are called decametric, metric, decimetric and resolution centimetric solar radio spectrometer, respectively. For the decametric solar radio spectrometer, the spectral resolution and temporal resolution have reached 7. 6 kHz and 1 ms, respectively. For metric and decametric, the spectral resolution and temporal resolution have reached 9. 5 kHz and 10 ms, respectively. For the centimetric spectrometer, the spectral and temporal resolution have reached 76 kHz and 10 ms, respectively. Each spectrometer includes antenna system, receiver and digital spectrometer. In order to obtain a spectrum with ultra-high spectral resolution, the maximum word length of FFT is 262 144, which cannot be achieved by one-time FFT in FPGA, the parallel FFT algorithm is need. For the large word length of FFT, the data need to be transformed into a FFT with two small word length by doing a row decomposition and then parallel processing. In this paper, the algorithm is studied and simulated by using Matlab, then is applied to digital spectrometer. The test results of the digital spectrometer are good consistency with the simulation, indicating the successful application of the algorithm on the digital spectrometer. This paper introduces the composition of solar radio spectrometer and the method of implementing ultra-high resolution based on FPGA.
Subjects: Astronomy >> Astrophysical processes submitted time 2022-05-30 Cooperative journals: 《天文研究与技术》
Abstract：耀斑和日冕物质抛射（Coronal Mass Ejection，CME）期间产生的非热高能粒子流和激波是产生灾害性空间天气事件的两种主要因素，它们主要观测特征分别是具有快速频率漂移特征的射电Ⅲ型暴和具有较为缓慢频率漂移的射电Ⅱ型暴。本文主要介绍了使用概率霍夫变换(Probabilistic Hough Transform)的方法，在观测数据中自动识别出太阳射电Ⅲ型暴和Ⅱ型射电暴，并提取射电Ⅲ和Ⅱ型暴的特征参数，最后利用识别出的射电Ⅱ型暴的物理参数估计了CME激波的速度。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-05-08 Cooperative journals: 《天文研究与技术》
Abstract：太阳射电爆发是无线通信特别是卫星导航通信的潜在影响因素之一。2015年11月4日的太阳射电爆发事件在1415MHz点频上的流量达到了峰值5800SFU(Solar Flux Unit)，位于日下点的欧洲GPS系统和瑞典的航空导航系统均受到了影响。本文分析了该次事件产生源活动区的X-ray流量变化与射电流量变化之间的时间前后关系；通过比对,X射线的流量抬升时间较之于射电阈值具有30分钟的提前量；随后本文讨论了该提前量之间的物理背景，即软硬X射线分别对应了热电子和非热电子辐射，而非热电子是产生能够造成该类空间天气事件射电爆发的物理条件，X射线由软转硬过程中流量的抬升变化，正好为进一步防控该类空间天气事件提供了一种有效的手段。
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