基于ROACH的Zoom-PFB设计与实现

Design and Implementation of a Digital Backend Incorporating a Zoom-PFB Algorithm Based on a ROACH System

简述了基于ROACH和Xilinx System Generator平台的接收机数字后端系统的设计与实现。介绍了Zoom-PFB算法原理,讨论了该算法的核心部分低通滤波和抽取的现场可编程门阵列(Field-Programmable Gate Array,FPGA)实现。针对谱线观测局部高精度分辨率的需要,给出了将400 MHz带宽分为带宽25 MHz的16个通道,对其中任一通道做通道数为6 k、频率分辨率为4 k Hz的频谱细化系统的具体设计方案。在实验室条件下,对该数字后端的性能进行了分析和测试,并以4.5 m口径X/Y结构天线进行银道面中性氢谱线观测检验其应用效果,验证了方案的可行性。

In this paper we describe design and implementation of a digital backend system for a radio-telescope receiver based on a ROACH system and a Xilinx System Generator.The system incorporates a Zoom-PFB algorithm.We first discuss principles of a Zoom-PFB algorithm and approaches to use an FPGA to realize the key parts of a Zoom-PFB, the low-bandpass filtering and decimation.To meet the demand of high-resolution observation of parts of spectra around a spectral line, we have designed the backend system by dividing its 400MHz bandwidth into 16 bands, each of which extends 25MHz and is further divided into 6k channels with a frequency resolution of about 4kHz.We have analyzed the specifications of the system and have carried out tests for its performance under laboratory conditions.We have also verified the feasibility of our design by using the system to observe the 21cm hydrogen line from the Galactic plane.The observation is through a radio telescope of a 4.5m antenna of the X/Y structure.