CAJ | 학술논문

数字终端技术在射电天文数据处理方面已成为主流，在国内外都有广泛的应用。回顾了滤波的基本原理，多相滤波技术在多通道滤波中的应用，探讨了对通道带通性能的优化方法。使用美国UC Berkeley CASPER团组研发的终端开发平台实现了一个观测带宽为400 MHz，通道数16 k，频谱分辨率约为25 kHz的数字终端，并进行了扫频测试。在设计中，模拟信号首先通过模拟数字转换器转换成数字信号，利用多相滤波器组算法实现多通道输出，并对每个通道内的数据进行取平方运算并累加得到功率谱。累加后的数据可通过10 GbE传输到其他设备存储或继续处理。该终端可在FAST河外中性氢频谱巡天观测中使用。
수자종단기술재사전천문수거처리방면이성위주류，재국내외도유엄범적응용。회고료려파적기본원리，다상려파기술재다통도려파중적응용，탐토료대통도대통성능적우화방법。사용미국UC Berkeley CASPER단조연발적종단개발평태실현료일개관측대관위400 MHz，통도수16 k，빈보분변솔약위25 kHz적수자종단，병진행료소빈측시。재설계중，모의신호수선통과모의수자전환기전환성수자신호，이용다상려파기조산법실현다통도수출，병대매개통도내적수거진행취평방운산병루가득도공솔보。루가후적수거가통과10 GbE전수도기타설비존저혹계속처리。해종단가재FAST하외중성경빈보순천관측중사용。
The digital-backend technique has become the main-stream signal-processing technology of radio astronomy and has been applied in China and abroad.In this paper we review the principles of signal filtering and application of polyphase filter banks ( PFBs) in multi-channel signal filtering.We particularly discuss approaches to optimize the bandpass performance using a PFB.Using the backend-developing platform provided by the CASPER of the UC Berkeley, we have designed and constructed a digital backend with a bandwidth of 400MHz divided into 16k channels ( corresponding to a frequency resolution of 25kHz) .We have also carried out a frequency-sweep test of the backend.The processing of the digital backend has been designed to be as follows.Input analog signals are converted into digital signals by an ADC.The digital signals are filtered by a PFB in multiple frequency channels, and the filtered signals in each channel are transformed by the FFT block to yield a power spectrum.The power spectra in multiple channels are summed and sent to other devices through a 10GbE interface for further processing or storage.The backend as designed can be applied in extragalactic HI surveys using the FAST radio telescope.