射电天文研究组知识库

传统的射电天文观测是一项繁琐且耗时的工作,需要在换源或定标时频繁地更换本振、滤波器等模块,但是大型望远镜的观测时间非常宝贵,因此提高射电望远镜的观测效率具有重要的意义。文中提出的捷变收发方案是软件无线电领域的一种新型设计方案,通过程控可以实现本振、滤波器等参数的快速切换,还可以实现快捷灵活的射电天文观测。在FPGA中实现数字信号处理,并对信号进行FFT处理和频域叠加,其模拟前端电路可以在程控下实现滤波器带宽的改变,达到在6 GHz带宽内对0.2～56 MHz带宽任意选取,从而在较小的采样频率下实现更高的时间分辨率和频谱分辨率。经过实验验证,文中平台在云南天文台40 m射电望远镜上能够取得良好的效果,并将射电天文定标的效率提高4～6倍。

The traditional radio astronomical observation is a tedious and time⁃consuming work, which requires frequent replacement of local oscillator, filter and other modules during source change or calibration. However, the observation time of large telescope is very valuable, so it is of great significance to improve the observation efficiency of radio telescope. The agile transceiver solution proposed in this paper is a new design scheme in the field of software radio. The rapid switching of local oscillator, filter and other parameters, and the fast and flexible radio astronomical observation can be realized by means of the program control. The digital signal processing can be implemented in the FPGA, and the FFT processing and frequency domain superposition for the signals are conducted. The analog front⁃end circuit can change the filter bandwidth under program control to arbitrarily select the 0. 2~56 MHz bandwidth within the 6 GHz bandwidth, so as to achieve higher time resolution and spectrum resolution at a lower sampling frequency. The experimental verification results show that the platform in this paper can achieve good effects on the 40 m radio telescope of Yunnan observatory, and increase the efficiency of radio astronomical calibration by 4~6 times.