Subjects: Astronomy >> Astrophysical processes submitted time 2023-12-06 Cooperative journals: 《天文研究与技术》
Abstract： In response to the requirements of high sampling rate, wide bandwidth, multi-channel amplitude-phase consistency as well as high-speed direct sampling and time-domain data storage in current radio observation devices, this paper investigates and analyzes the technical architecture and functionalities of digital processing systems in multiple radio observation devices. It proposes a 4-channel digital receiver system based on ZYNQ SOC and core components such as ADS54J60. This system achieves a maximum sampling rate of 1GSPS per single channel, demonstrating flexibility and scalability, which allows for the addition of expansion cards to increase sampling channels for meeting the fundamental requirements of future large-scale expandable radio interference arrays. The system consists of three parts: a high-speed data acquisition card, an optical communication receiving card, and a server. Currently, the high-speed serial interface technology based on SerDes has achieved direct sampling with a quantization accuracy of 16 bits and a sampling rate of 300 MSPS, providing a full-scale signal-to-noise ratio of 60 dB, a 40 Gbps SFP+ data transmission bandwidth, and a 1.5 GB/ s PCIe communication bandwidth. It can capture analog signals in the intermediate frequency range of 4.5 MHz to 150 MHz. The system has completed both hardware and software design and testing. In our tests, we sampled a 10 MHz sine wave signal with an amplitude of 125 mV, and the amplitude difference between the 4 channels was less than 1 mV, with a phase delay of less than 3.3 ns. The system integrates programmable SFP+ communication interfaces and a multi-machine synchronization mechanism to accommodate the synchronous acquisition needs of multi-element arrays. It can also store the data of the original radio signals, providing more detailed time-domain data for radio research.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-03-13 Cooperative journals: 《天文研究与技术》
Abstract： Low-frequency radio observations on the lunar surface have great potential for scientific discovery and are expected to reveal the secrets of the dark age and cosmic dawn of the Universe. This paper proposes a new design for low-frequency radio lunar observation. The non-Foster matching circuit is used to significantly reduce the physical size of the antenna, making it light and easy to deploy on the moon. First, an electrically small membrane antenna which is light，wide temperature range，malleable，foldable, simple to deploy, and with good omnidirectionality is designed，gain is less than 1.92dB in 4-8Mhz and half-beam width is greater than 83 °. Then, a non-Foster matching circuit is employed to improve impedance performance ，the reactance of the antenna is optimized from about -985.3 Ω to-16.5 Ω, and the noise power level is less than - 150 dBm in most frequency range. Finally, The feasibility of the design is preliminarily confirmed by impedance and noise measurement.
Subjects: Astronomy >> Astrophysical processes submitted time 2017-10-20 Cooperative journals: 《天文研究与技术》
Abstract：随看射电干涉技术的不断提升，干涉阵列规模越来越大，观测能力逐渐增强，但随之而来的是超大数据的实时处理问题。针对该问题，结合射电干涉仪相关器在数据运算和传输等方面的需求以及射电干涉阵列信号的特征，研制了一套基于图形处理器集群的通用相关器并用于“天籁计划”的数据处理:首先根据射电信号的关联计算特性，按频段将计算任务分配到不同图形处理器节点，并合理均衡各节点网络负载;然后由不同图形处理器节点独立完成各自的计算任务并将计算结果实时送往存储节点;最后按图形处理器集群通用相关器的设计方案成功安装部署系统并根据“天籁计划”一期的需求进行了性能测试。该图形处理器集群相关器计算性能约为理论峰值性能的46%;相对于传统方案的相关器，基于图形处理器集群的相关器具有开发周期短、可扩展性强、部署简单等优势。
Subjects: Astronomy >> Astrophysical processes submitted time 2017-09-26 Cooperative journals: 《天文研究与技术》
Abstract：相关器在射电天文中具有重要作用。以往的相关器多采用现场可编程门阵( Field-Programmable Gate Array, FPGA)或者特定用途集成电路(Application Specific Integrated Circuit, ASIC)技术，开发周期长，不便扩展和改进升级。近年来许多新研制的射电干涉阵相关器采用具有通用架构的现场可编程门阵列和图形处理器的相关器。针对暗能量射电探测实验(天籁计划)的需求，开发了一套基于可重构开放架构计算硬件(Reconfigurable Open ArchitectureComputing Hardware, ROACH2)和图形处理器的异构相关器，将相关器的数据采集快速傅里叶变换(Fast Fourier Transform , FFT)等功能与复数乘累加运算功能分开，充分利用了现场可编程门阵列的硬件资源和图形处理器的运算速度。该相关器易于扩展，且运算负载可根据实际运算能力进行不同节点的分配，非常灵活。目前已经应用到天籁计划项目中。
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