核信号数字滤波处理技术的研究

发布时间：2018-03-27 18:30

本文选题：核脉冲信号　切入点：数字滤波器　出处：《成都理工大学》2015年硕士论文

【摘要】：随着高速ADC各种数字化高集成度的可编程器件(FPGA和CPLD)、实时操作系统和微处理器的快速发展,数字信号处理技术在核物理领域也得到了极大的发展。粒子探测器将入射粒子的能量转变成电信号,经过前置放大电路和主放大电路将微弱信号放大至ADC能采样的信号,在这个过程中不可避免地会产生噪声。由于环境中本底的影响及电子学系统的噪声影响,使得采样的脉冲数据有很大的统计涨落。正是噪声的存在,为后续电路对脉冲幅度甄别中,加宽了能谱曲线,影响系统的能量分辨率,降低了测量精度。而数字滤波处理技术是当前数字信号处理的热点及难点,如何有效正确的处理噪声而保留有用信号,是本论文的主要研究内容。核脉冲信号的基本参数有3个分别是：幅值、衰减常数和时间间隔。核脉冲信号的幅值服从正态分布—围绕某个值上下波动,而核信号的时间间隔服从指数分布,核脉冲信号本身服从负指数分布,任何情况下噪声总是叠加在有用信号上,论文详尽阐述了利用上述统计分布产生了理想核脉冲信号及带噪声的核脉冲信号,为后续数字滤波算法的研究提供了原始数据。在此基础上,论文对构建的FIR数字滤波器及S-K数字滤波器的原理进行了介绍,并对滤波参数的选择进行了实验,初步确定了参数选择原则。通过研究FIR数字滤波器和S-K数字滤波器对模拟核脉冲信号的处理效果研究,得出S-K数字滤波器的滤波能力较FIR数字滤波能力高。通过模拟大量核信号并生成谱图研究两种方法对谱线能量分辨率和计数率的影响,得出S-K数字滤波器能有效改善能量分辨率。但是经过S-K数字滤波器的核脉冲信号的脉冲宽度会增加,在高计数率情况下,经过S-K数字滤波器得到谱线的计数率较FIR数字滤波器得到谱线的计数率偏低。最后,通过搭建实际硬件测试平台,对FIR数字滤波器在保证了能量分辨率的前提下,提高了系统的脉冲通过率,更适用于高放射性的测量环境。
[Abstract]:With the rapid development of high speed ADC digital and high integration programmable devices, real time operating system and microprocessor, The technology of digital signal processing has also been greatly developed in nuclear physics. Particle detectors convert the energy of incident particles into electrical signals, and amplify the weak signals to the signals that ADC can sample through the preamplifier circuit and the main amplifier circuit. It is inevitable to produce noise in this process. Because of the background influence in the environment and the noise effect of the electronic system, the sampled pulse data have great statistical fluctuation. It is the noise that exists. In order to distinguish the pulse amplitude in the subsequent circuit, the energy spectrum curve is widened, the energy resolution of the system is affected, and the measurement accuracy is reduced. The digital filter processing technology is the hot and difficult point in the digital signal processing at present. How to deal with noise and retain useful signals effectively and correctly is the main research content in this paper. Attenuation constant and time interval. The amplitude of a nuclear pulse signal fluctuates from normal distribution-up and down around a certain value, while the time interval of a nuclear signal is distributed exponentially, and the nuclear pulse signal itself takes a negative exponential distribution. In any case, noise is always superimposed on the useful signal. In this paper, the ideal nuclear pulse signal and the nuclear pulse signal with noise are generated by using the above statistical distribution in detail. On the basis of this, the principle of FIR digital filter and S-K digital filter are introduced, and the selection of filter parameters is experimented. The principle of parameter selection is preliminarily determined. By studying the processing effect of FIR digital filter and S-K digital filter on analogue nuclear pulse signal, It is concluded that the filtering ability of S-K digital filter is higher than that of FIR digital filter. The influence of two methods on the energy resolution and counting rate of spectral lines is studied by simulating a large number of nuclear signals and generating spectrum diagrams. It is concluded that S-K digital filter can effectively improve the energy resolution, but the pulse width of the nuclear pulse signal passing through S-K digital filter will increase, in the case of high counting rate, The counting rate of the spectrum line obtained by S-K digital filter is lower than that by FIR digital filter. Finally, through building the actual hardware test platform, the FIR digital filter can guarantee the energy resolution. The pulse pass rate of the system is improved, which is more suitable for high radioactivity measurement environment.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN713

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