用于射电天文数字频谱仪的新进展

New Progress on Digital Spectrometer for Radio Astronomy

根据在射电天文频谱观测中出现的新需求,介绍了近年来数字技术的新进展.达到GHz采样速率的多位高速模数转换器(Analog-to-Digital Converter,ADC)、海量数字处理芯片现场可编程门阵列(Field Programmable Gate Array,FPGA)以及运行在这些芯片上的并行快速傅里叶变换知识产权(Fast Fourier Transform Intellectual Property,FFT IP)内核,结合高性能数据总线的系统集成,为射电天文构建新型FFT频谱仪提供了可能的技术选择.与现有其他类型频谱仪相比,集成了这些新技术的数字型FFT频谱仪有更大的带宽、更高的谱分辨率、更高的动态范围和整体稳定性,此类频谱仪的出现显示了射电频谱技术已经进入了新一代数字技术应用的阶段.

Spectrometers for radio astronomy have provided an important tool for observations of interstellar molecular clouds, star forming regions, supernova remnants and other targets. The new scientific demands on astronomical observation include wider bandwidth, higher spectral resolution and capability for deep integration. These new technical aspects cannot be fulfilled by traditional analog backends such as acousto-optical spectrometer （AOS）, so enhancing performance of backend is highly demanded. A new progress on the key technological features of radio spectroscopy is investigated and summarized in this paper. Based on the system integration of multi-bit ADC （capable of GHz sampling rate）, parallel FFT IP cores running on large capac- ity FPGA, high-performance BUS technology, a novel FFT spectrometer for radio astronomy becomes possible. Digital FFT spectrometer which integrates these new technologies has wider bandwidth, finer spectral resolution, higher dynamic range and system stability in comparison with other types of spectrometer. Limited efforts show that this kind of digital technology may help us in developing sophisticated spectroscopes for radio astronomy. The same architecture can also be used for other applications in radio astronomy, such as the de-dispersion backend in pulsar observation as well as cross correlation in radio interferometers.