射电望远镜新型数字多波段观测终端关键技术研究

项目名称： 射电望远镜新型数字多波段观测终端关键技术研究

项目编号： No.U1231122

项目类型： 联合基金项目

立项/批准年度： 2013

项目学科： 天文学、地球科学

项目作者： 柏正尧

作者单位： 云南大学

项目金额： 50万元

中文摘要： 云南天文台四十米射电望远镜即将进行馈源改造和升级，改造后的射电望远镜配合新的频谱分析终端将在谱线轮廓观测、总流量观测中发挥重要作用。射电天文中传统的宽带终端是基于过采样理论设计的，在时间分辨率、频率分辨率以及处理器资源等方面存在矛盾，制约了其在窄带、多线谱、精细结构观测中的性能。基于亚奈奎斯特采样理论并利用ADC的宽输入带宽特性，可用相对较低的采样率同时对多个中频频段进行采集。通过前端的模拟滤波器构建抗混叠滤波器组，既可以实现宽带数据采集，也可以通过单片ADC实现分散的多窄频观测。由于采样率相对较低，数据量大大低于现有的宽带终端。本项目对基于亚奈奎斯特采样的多波段天文观测终端研制中的几个关键问题进行研究，包括抗混叠滤波器拼接实现宽带输入和相关后端数字补偿研究，高速宽带输入ADC性能研究，以及基于FPGA实时控制高速数据采集和信号分析等。该研究将为新型天文观测终端的研制奠定理论和技术基础。

中文关键词： 亚奈奎斯特采样；高动态范围；高频率分辨率；多波段观测；射电望远镜

英文摘要： The feeds of 40-metre radio telescope in Yunnan Observatory will be transformed and improved. The transformed radio telescope with the new feeds and the new spectrum analysis backends will play an important role in spectrum lines profile and flow observations. But the traditional wide-band backends are based on the oversampling theory-the first Nyquist sampling theorem that the sampling rate is more than twice of the highest frequency of the input signal. The time resolution, frequency resolution and processor resources of these instruments limited their applications in the fine structure observations with narrow and multi bands. The sub-Nyquist sampling theory takes advantage of the ADC''s wide input feature, so the new instruments based on sub-Nyquist theory can sample multiple intermediate frequency bands at the same time with comparatively low sampling rate. Through the anti-alias filter bank based on analog filters, we can not only achieve the wide band signal sampling, but also achieve multiple discrete spectrum lines observations with a single ADC chip. Because of the low sampling rate, data in the new backends can be largely reduced compared with traditional ones. This project aims to do the research of the key technologies in development of the multi-band astronomical observation backends based on sub

英文关键词： sub-Nyquist sampling；high dynamic range；high frequency resolution；muti-band observation；radio telescope