本文選題：核脈沖信號　切入點：數(shù)字濾波器　出處：《成都理工大學》2015年碩士論文

【摘要】：隨著高速ADC各種數(shù)字化高集成度的可編程器件(FPGA和CPLD)、實時操作系統(tǒng)和微處理器的快速發(fā)展,數(shù)字信號處理技術(shù)在核物理領(lǐng)域也得到了極大的發(fā)展。粒子探測器將入射粒子的能量轉(zhuǎn)變成電信號,經(jīng)過前置放大電路和主放大電路將微弱信號放大至ADC能采樣的信號,在這個過程中不可避免地會產(chǎn)生噪聲。由于環(huán)境中本底的影響及電子學系統(tǒng)的噪聲影響,使得采樣的脈沖數(shù)據(jù)有很大的統(tǒng)計漲落。正是噪聲的存在,為后續(xù)電路對脈沖幅度甄別中,加寬了能譜曲線,影響系統(tǒng)的能量分辨率,降低了測量精度。而數(shù)字濾波處理技術(shù)是當前數(shù)字信號處理的熱點及難點,如何有效正確的處理噪聲而保留有用信號,是本論文的主要研究內(nèi)容。核脈沖信號的基本參數(shù)有3個分別是：幅值、衰減常數(shù)和時間間隔。核脈沖信號的幅值服從正態(tài)分布—圍繞某個值上下波動,而核信號的時間間隔服從指數(shù)分布,核脈沖信號本身服從負指數(shù)分布,任何情況下噪聲總是疊加在有用信號上,論文詳盡闡述了利用上述統(tǒng)計分布產(chǎn)生了理想核脈沖信號及帶噪聲的核脈沖信號,為后續(xù)數(shù)字濾波算法的研究提供了原始數(shù)據(jù)。在此基礎(chǔ)上,論文對構(gòu)建的FIR數(shù)字濾波器及S-K數(shù)字濾波器的原理進行了介紹,并對濾波參數(shù)的選擇進行了實驗,初步確定了參數(shù)選擇原則。通過研究FIR數(shù)字濾波器和S-K數(shù)字濾波器對模擬核脈沖信號的處理效果研究,得出S-K數(shù)字濾波器的濾波能力較FIR數(shù)字濾波能力高。通過模擬大量核信號并生成譜圖研究兩種方法對譜線能量分辨率和計數(shù)率的影響,得出S-K數(shù)字濾波器能有效改善能量分辨率。但是經(jīng)過S-K數(shù)字濾波器的核脈沖信號的脈沖寬度會增加,在高計數(shù)率情況下,經(jīng)過S-K數(shù)字濾波器得到譜線的計數(shù)率較FIR數(shù)字濾波器得到譜線的計數(shù)率偏低。最后,通過搭建實際硬件測試平臺,對FIR數(shù)字濾波器在保證了能量分辨率的前提下,提高了系統(tǒng)的脈沖通過率,更適用于高放射性的測量環(huán)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.
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN713

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本文編號：1672719