基于多相滤波的多通道数字终端设计  

A Design of a Multi-Channel Digital Backend Based on a Polyphase Filter Bank

作　　者：赵欣[1,2] 金乘进[1] 朱岩[1] 岳友岭[1] 吴俊霖[1,2] 

机构地区：[1]中国科学院国家天文台,北京100012 [2]中国科学院大学,北京100049

出　　处：《天文研究与技术》2015年第4期495-502,共8页Astronomical Research & Technology

基　　金：国家重点基础研究发展计划(973计划)(2012CB821800);国家重点基础研究发展计划(973计划)(2013CB837900);国家自然科学基金(11373045);国家自然科学基金国际合作与交流项目(11261140641);中国科学院重点部署项目(KJZD-EW-T01)资助

摘　　要：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 k Hz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。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.

关 键 词：多相滤波 多通道滤波 10GbE 数字终端 

分 类 号：P111.44[天文地球—天文学]