高速PCIE总线在核信号实时采集系统中的应用

发布时间：2018-08-26 20:02

【摘要】：在核信号探测领域,核信号采集是获取核辐射场能量信息以及时间信息的重要手段之一。一个简单的核辐射脉冲信号却包含了很多重要信息,其中包括射线能量、种类以及时间等。因此,核信号的准确获取对核辐射能量场的分析具有很重要的意义。通常情况下,核信号的采集是先将数据进行模数转换,然后再对转换后的数字信号进行处理。在高速数字化的今天,模数转换器(ADC)的性能指标不断提升,同时对数据传输速率也产生了一定的要求。本文采用高速ADC和性能强大的FPGA,再配合高速PCIE数据传输总线构建出了一套实时核信号采集系统。该系统不但能获取核脉冲信号幅度信息,还可以实时显示所采集的波形,也可以在PC端完成相关算法的实时验证。目前,针对核辐射场的探测分析通常是采用成谱的方式进行,其中包括:前端信号调理、信号采集、FPGA内部算法处理以及最终成谱并显示。整个过程并未涉及对原始核信号的实时显示或存储,这不利于对信号的实时监控或对原始数据的事后处理。本文针对这一问题设计一套核信号实时显示、采集、存储系统。本论文选题来自于国家863计划课题“高精度能谱探测仪器研发”(课题编号:2012AA061803)。设计出一套基于高性能Xilinx FPGA(XC7K410T)和高速PCIE总线的核信号实时采集系统。其中,采集部分采用200Msps、16位的高速ADC采样芯片,该芯片对于上升时间在纳秒级和脉宽在几百纳秒的核信号具有很好的采样效果,能满足高速采样的要求。采集所得到数据位宽为16位,产生的数据流速为200Msps*16Bit=400MB/s。数据传输采用PCIE Gen2.0标准,实测传输速率达到约3.0GB/s。为满足上述速率,组建了一个RAID磁盘阵列,其写盘速度通过HD Tune Pro测试为800MB/s。对于高速数据传输采用DMA乒乓方式完成,并对每个数据交互过程中每个环节的开销进行分析,并设计出一套合理的DMA交互机制。驱动部分采用WinDriver 12.20进行开发,其us级的中断响应,满足该核信号系统的采集需求。应用软件部分用Qt进行设计,为了满足核信号的实时显示并存储,采用多线程设计,以便程序的顺利运行。最后,利用本系统对实际核信号进行采集,并验证设计的可行性。通过对NaI闪烁体探测输出137Cs的核信号波形进行实时采集,并在应用程序上显示完整的原始波形,并对其进行了讨论。此外,用信号源进行线性度测量,得到线性度为0.9999。采用滑动平均算法验证平台的可行性,也得到良好的效果。实验表明,基于高速PCIE的实时核信号采集系统的方案是成功可行的,且对高速核信号采集和实时传输的研究有重要推动作用,同时具有一定的研究价值和应用前景。
[Abstract]:In the field of nuclear signal detection, nuclear signal acquisition is one of the important means to obtain energy information and time information of nuclear radiation field. A simple nuclear pulse contains a lot of important information, including ray energy, type and time. Therefore, the accurate acquisition of nuclear signals is of great significance to the analysis of nuclear radiation energy field. Usually, the acquisition of nuclear signal is to convert the data into A / D first, and then to process the converted digital signal. With the development of high speed digitization, the performance of ADC (ADC) is improved continuously, and the data transmission rate is also required. In this paper, a real time nuclear signal acquisition system is constructed by using high speed ADC and powerful FPGA, combined with high speed PCIE data transmission bus. The system can not only obtain the amplitude information of the nuclear pulse signal, but also display the collected waveform in real time, and can also complete the real-time verification of the algorithm at the PC end. At present, the detection and analysis of nuclear radiation field is usually carried out in a spectral way, which includes: front end signal conditioning, signal acquisition and FPGA internal algorithm processing, and final spectrum and display. The whole process does not involve the real-time display or storage of the original nuclear signal, which is not conducive to the real-time monitoring of the signal or the post-processing of the original data. In order to solve this problem, this paper designs a real-time nuclear signal display, acquisition and storage system. The topic of this thesis comes from the research and development of high precision energy spectrum detector (project No.: 2012AA061803). A real-time nuclear signal acquisition system based on high performance Xilinx FPGA (XC7K410T) and high speed PCIE bus is designed. Among them, the acquisition part uses a high-speed ADC sampling chip of 200mspsSZ, which has a good sampling effect for the nuclear signal with rising time at nanosecond and pulse width at several hundred nanoseconds, and can meet the requirement of high-speed sampling. The obtained data bit width is 16 bits and the data flow rate is 200 Msps1 / 16 Bitt / s. The data transmission is based on PCIE Gen2.0 standard, and the measured transmission rate is about 3.0 GB / s. To satisfy the above rate, a RAID disk array was constructed, and the write disk speed passed the HD Tune Pro test of 800MB / s. The high-speed data transmission is accomplished by DMA ping-pong mode, and the cost of each link in the process of data exchange is analyzed, and a set of reasonable DMA interaction mechanism is designed. The driver part is developed with WinDriver 12.20, and its us level interrupt response can meet the acquisition requirement of the nuclear signal system. The application software is designed with Qt. In order to meet the real-time display and storage of the nuclear signal, multithread design is adopted so that the program can run smoothly. Finally, the system is used to collect the actual nuclear signals and verify the feasibility of the design. The nuclear signal waveform of NaI scintillator detection output 137Cs is collected in real time, and the complete original waveform is displayed in the application program and discussed. In addition, the linearity is measured by signal source, and the linearity is 0.9999. The feasibility of the platform is verified by moving average algorithm, and good results are obtained. The experimental results show that the scheme of real-time nuclear signal acquisition system based on high-speed PCIE is successful and feasible, and it plays an important role in the research of high-speed nuclear signal acquisition and real-time transmission, and has certain research value and application prospect.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP274.2

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