【摘要】 数字化是目前设备研制发展的趋势,介绍了中国科学院上海天文台利用超大规模集成电路结合软件无线电技术,自主研发的我国新一代VLBI数字基带转换器(Chinese Data Acquisition System,简称CDAS)。文中描述了设备的工作原理及其组成,并以VLBI观测实验数据证明其可行性。与原有的模拟设备(Analog Baseband Convertor,简称ABBC)相比,新设备具有体积小,可靠性高,性能好,可维护性强等优点。该设备作为VLBI台站终端系统的核心部分,安装在上海、北京、昆明和乌鲁木齐等相关台站,为我国VLBI技术用于天文观测、大地测量和航天器测轨服务。更多还原

【Abstract】 With the development of software radio technologies,especially the using of programmable components,more and more equipments can be digitalized for its convenience,efficiency and reliability. The Chinese Data Acquisition System(CDAS) independently designed by Shanghai Astronomical Observatory of CAS is a digitalized base band covertor for VLBI,which can take the place of traditional analogy base band covertor.It consists of two parts.One is responsible for AGC (Automatic Gain Control) and anti-aliasing,which keeps the optimal quantization level for the ADC following.The other is responsible for data acquisition and process,which quantifies 512 MHz wideband signal by a high speed ADC and splits the broadband up to 32 baseband after calculating by FPGAs in real time.It also can be connected with either MK4 or MK5 recorder. This article describes the principle of phase-shifting method applied,framework composed and experiment results obtained by CDAS.Compared to the traditional analog base-band converter, the experiment results obtained in terms of band-pass characteristics,SNR(signal-noise ratio) and delay dispersion for example,show the performance improvement of CDAS. CDAS is not only smaller in size,but also higher performance.It will serve for geodesy, astrometry,and spacecraft orbit determination.更多还原