共查询到20条相似文献,搜索用时 23 毫秒
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With the development on high-speed integrated circuit,fast high resolution sampling ADC and digital signal processors are replacing analog shaping amplifier circuit.This paper firstly presents the numerical analysis and simulation on R-C shaping circuit model and C-R shaping circuit model.Mathematic models are established based on 1st order digital differential method and Kirchhoff Current Law in time domain,and a simulation and error evaluation experiment on an ideal digital signal are carried out with Excel VBA.A digital shaping test for a semiconductor X-ray detector in real time is also presented.Then a numerical analysis for Sallen-Key(S-K) low-pass filter circuit model is implemented based on the analysis of digital R-C and digital C-R shaping methods.By applying the 2nd order non-homogeneous differential equation,the authors implement a digital Gaussian filter model for a standard exponential-decaying signal and a nuclear pulse signal.Finally,computer simulations and experimental tests are carried out and the results show the possibility of the digital pulse processing algorithms. 相似文献
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本文提出一种基于80 MHz ADC的数字化γ能谱系统。系统由探测器、前端电路、ADC和数字处理单元组成。数字处理在FPGA中完成,主要包括FIR数字滤波、脉冲梯形成形、幅度甄别、数据通讯。为减小高速ADC在采集过程中引入的噪声信号,在数字处理单元实现FIR数字滤波,对数字脉冲信号先进行滤波处理,再进行脉冲梯形成形,得到高分辨率的能谱数据。测量系统中模拟信号全部采用直流耦合,数字脉冲宽度为1.6μs,对137 Cs的能量分辨率达6.88%。 相似文献
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核脉冲信号成形前的指数信号往往含有较为丰富的高频信号并叠加有噪音,使指数信号的参数识别变得困难,对此,本文提出一种通过成形后的信号反推成形前参数的方法。采用S-K高斯数字成形算法和种群技术,由高斯信号搜寻指数信号的参数。结果表明,该方法得到的指数脉冲参数精度高:幅值和产生时间误差在1%以内,时间常数误差为2%左右,是一种性能良好的脉冲识别方法。 相似文献
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Identification of nuclear pulse signal is of importance in radioactive measurements,especially in recognizing adjacent overlapping nuclear pulses.In this article,we propose an estimation method for parameters of typical overlapping nuclear pulse signals.First,the nuclear pulses are regarded as individual genes and the norm is set as the fitness function.Second,the global optimal solution is found by searching the population of genetic algorithm,so as to estimate the parameters of nuclear pulse.With high precision,this method can identify parameters of overlapping nuclear pulses in the Sallen-Key Gaussian signal decomposition experiments.This pulse recognition method is of great significance to improve the precision of radioactive measurement and is suitable for serious overlap of nuclear pluses. 相似文献
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介绍了一种数字化多道脉冲幅度分析器(DMCA),该系统采用数字梯形滤波成形等数字信号处理方法进行核脉冲信号处理,采用NOISII软核处理器进行数据处理,所有数字功能均在单片FPGA中实现。测试表明,该系统转换增益可达4 096道,最大脉冲通过率可达200 kcps以上。 相似文献
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The design of a fast, programmable, stand-alone pulse generator emulating spectroscopy nuclear events is described. The generator is one unit in a system aiming to test the validity of the simulation and theoretical work relating to the shaping, acquisition, and processing of spectroscopy signals in different experimental situations arising from different technical and scientific fields. The generator output, which also includes piled-up shapes, can be used in many different ways. For example, it can be used: (1) as an input to a charge sensitive preamplifier and shaping amplifier system; (2) as an input to a module for real-time digital shaping of spectroscopy pulses; and (3) it can generate a digital sequence emulating a digitally sampled analog pulse. The signals that it can emulate include those from simple charge sensitive preamplifiers, from more refined analog shapers, and the signals generated directly from scintillation detectors. The main element of the generator is the Analog Devices 21060, a fast and flexible digital signal processor (DSP). This paper considers various generator configurations arising from the need to reach a compromise among generator speed, shape resolution, and memory requirements. It is possible to program both the emulated average counting rate and the time interval between two consecutive samples (tns) using a predetermined pulse shape. The minimum tns value is equal to 10 ns in parallel configurations 相似文献
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High-accuracy fit of the poles of spectroscopy amplifiers designedfor mixed analog-digital filtering
Bittanti S. Gatti E. Ripamonti G. Savaresi S.M. 《IEEE transactions on nuclear science》1997,44(2):125-133
In this paper, a method for the identification of the poles' and zeros' position of an analog amplifier for nuclear spectroscopy used as a prefilter for a subsequent digital filter setup is presented. The proposed technique is based upon a subspace-based system state-space identification (4SID) method, which is well suited to a data set constituted by a noisy measurement of the sampled impulse response of the circuit. The algorithm runs unassisted and does not require skills by the operator. The experiments confirm that by using the so-obtained pole values, the shape of the impulse response of the amplifier can be fit with much better than 1% accuracy. Consequently, the overall filtering (analog+digital) can have finite duration and a top with a flatness much better than 1% 相似文献
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Pulse shaping,which improves signal-to-noise ratio excellently,has been extensively used in nuclear signal processing.This paper presents a cusp-like pulse-shaping technique developed through the recursive difference equation in time domain.It can be implemented in field programmable gate array hardware system.Another fiat-topped cusp-like shaper is developed to optimize the time constant of pulse shaping and reduce the influence of ballistic deficit.The methods of both baseline restoration and pile-up rejection are described.The 137Cs energy spectra measured with the digital cusp-like shaper are 6.6% energy resolution,while those by traditional analog pulse shaper are 7.2% energy resolution,under the same conditions.This technique offers flexibility,too,in adjusting the pulse shaper parameters. 相似文献
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多道脉冲幅度分析中的数字基线估计方法 总被引:2,自引:0,他引:2
介绍了用于多道脉冲幅度分析的数字基线估计方法的基本特点,利用泛函变分方法推导了最小噪声基线滤波器的计权函数.利用Fourier变换导出了数字基线估计的频率响应,探讨了参数取值对其幅频特性的影响。还利用MATLAB模拟了电荷灵敏前置放大器输出的噪声电压信号,验证了最小噪声数字基线估计的处理效果。研究结果表明,数字基线估计方法能实现最佳基线估计,特别适于在数字化多道脉冲幅度分析中使用。 相似文献
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慢衰减型闪烁体(NaI(Tl)、CsI(Tl)等)探测器经过前放输出的脉冲信号具有较长的上升时间,造成电荷在收集的过程中出现严重的弹道亏损。在后续脉冲成形中为了降低弹道亏损对能量分辨率的影响,一般采用较宽的成形平顶来增加电荷的收集时间。但在高辐射粒子注量率的场合下,由于慢衰减型闪烁体输出的脉冲堆积严重,采用传统的滤波成形方式获得的脉冲计数率和能量分辨率明显降低。为解决此问题,本文提出了一种以数字反褶积为核心的数字快成形算法。该算法可去掉慢衰减型闪烁体探测系统的衰减电流拖尾,获得一理想的冲激脉冲电流,然后再通过滤波成形为一窄脉冲,并彻底消除弹道亏损的影响。通过对~(137) Csγ源测量,使用传统成形算法的能谱测量系统在成形时间为1.5μs时,其光电峰能量分辨率为6.99%,计数率为68 000s~(-1);而使用数字快成形系统,在相同情况下获得6.37%的能量分辨率,计数率可达102 000s~(-1)。因此数字快成形算法可有效地修复在高辐射粒子注量率下,窄脉冲成形引起的信号变形和拖尾,从而提高了脉冲堆积甄别能力。 相似文献
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单探测器宽量程剂量仪测量范围能超过8个数量级,远大于常规脉冲计数法的剂量仪。在单探测器宽量程剂量仪中,平均等待时间的计算误差直接关系到最终辐射强度或剂量率的计算精度。平均时间求取的实质是采用低通滤波器处理等待时间。信号处理领域中成熟的数字滤波器设计的基础是信号频谱分析,没有考虑核探测中的随机因素,由其设计的滤波器不能同时提高响应速度与测量精度这两个指标。针对单探测器宽量程剂量仪测量等待时间与数字滤波器设计方法的特点,本文提出了基于多目标粒子群优化的滤波器设计方法。理论分析与实验结果均表明:与传统方法所设计的滤波器相比,本文方法所设计的滤波器在相同测量精度条件下具有最快的响应速度;在相同响应速度条件下,具有最高的测量精度。本方法适用于设计宽量程剂量仪或其他类型辐射测量装置的数字滤波器。 相似文献