CN103941280A - Digital nuclear pulse Gauss shaping method based on impulse response invariance method - Google Patents

Abstract

The invention discloses a digital nuclear pulse Gauss shaping method based on an impulse response invariance method. The digital nuclear pulse Gauss shaping method comprises that: according to a circuit of a simulation Gauss shaping system, a differential equation of a system circuit input signal and an output signal is obtained, and the differential equation is deduced via frequency domain analysis so that unit impulse response of the simulation Gauss system is acquired; frequency response of the simulation Gauss shaping system is analyzed, and frequency for performing sampling of the simulation Gauss shaping system is confirmed according to the spectral range of the frequency response; the simulation Gauss shaping system is converted from a simulation domain to a digital domain by using the impulse response invariance method so that the unit impulse response of a digital Gauss shaping system is obtained, and the impulse response comprises shaping parameters capable of adjusting waveform width; the shaping parameters in the impulse response are selected, and the unit impulse response of the corresponding digital Gauss shaping system is confirmed according to the selected shaping parameters; and convolution and operation are performed on a nuclear pulse signal inputted to the digital Gauss shaping system and the unit impulse response of the digital Gauss shaping system so that digital nuclear pulse Gauss shaping is realized.

Description

Digital core pulse Gauss manufacturing process based on Impulse invariance procedure

Technical field

The Gauss who the present invention relates to digital core pulse in radioactivity survey is shaped, and relates in particular to a kind of digital core pulse Gauss manufacturing process based on Impulse invariance procedure.

Background technology

In nuclear spectrum measurement system, for convenience of subsequent conditioning circuit, process and analyze and reduce pulse pile-up and improve signal to noise ratio (S/N ratio), need be suitable waveform by the signal shaping of detector output.The signal to noise ratio (S/N ratio) of Gaussian waveform is high, top is more smooth, ballistic deficit is less, by the signal shaping of detector output, is often therefore Gauss or accurate Gaussian waveform.Simulation Gauss is shaped and can uses simulation Sallen-Key wave filter to realize, but the formation system of realizing due to mimic channel, changing over shape parameter must adjust hardware; Digital forming does not need adjustment System hardware, has higher dirigibility and stability, and digital Gauss's shaping Algorithm becomes the focus of Nuclear signal processing research in recent years.

Summary of the invention

For solving the problems of the technologies described above, the object of this invention is to provide a kind of digital core pulse Gauss manufacturing process based on Impulse invariance procedure.The method has overcome the deficiency that core pulse simulation Gauss is shaped, and the digital Gauss who the has solved core pulse demand that is shaped, for the digitizing of nuclear instrument is laid a good foundation.

Object of the present invention realizes by following technical scheme:

Digital core pulse Gauss manufacturing process based on Impulse invariance procedure, comprising:

According to the circuit of simulation Gauss formation system, obtain the differential equation of circuit system input signal and output signal, the differential equation is derived by frequency-domain analysis, obtain the unit impulse response of simulation Gaussian Systems;

The frequency response of analysis mode Gauss formation system, and according to the spectral range of frequency response, determine the frequency that simulation Gauss formation system is sampled;

Simulation Gauss formation system is converted to numeric field with Impulse invariance procedure by analog domain, obtains the unit impulse response of digital Gauss's formation system, in described impulse response, contain the forming parameter that can adjust waveform width;

Select the forming parameter in impulse response, and according to selected forming parameter value, determine the unit impulse response of corresponding digital Gauss's formation system;

To be input to the core pulse signal of digital Gauss's formation system and the unit impulse response of digital Gauss's formation system carries out convolution and computing, realize digital core pulse Gauss and be shaped.

Compared with prior art, one or more embodiment of the present invention can have the following advantages by tool:

Effectively overcome the deficiency of simulation Gauss formation system, by the digital core pulse signal Gaussian waveform that is as the criterion that is shaped, and can be according to shaping waveform needed to flexible parameter value in using, to meet different measurement demands, the energy resolution of raising system, for the real-time implementation that Gauss pulse in digital core energy depressive spectroscopy is shaped is laid a good foundation.

Other features and advantages of the present invention will be set forth in the following description, and, partly from instructions, become apparent, or understand by implementing the present invention.Object of the present invention and other advantages can be realized and be obtained by specifically noted structure in instructions, claims and accompanying drawing.

Accompanying drawing explanation

Accompanying drawing is used to provide a further understanding of the present invention, and forms a part for instructions,, jointly for explaining the present invention, is not construed as limiting the invention with embodiments of the invention.In the accompanying drawings:

Fig. 1 is the be shaped process flow diagram of implementation procedure of digital Gauss;

Fig. 2 is the circuit theory diagrams of simulation Gauss formation system;

Fig. 3 is Gauss corresponding to the different parameters value waveform that is shaped.

Embodiment

Easily understand, according to technical scheme of the present invention, do not changing under connotation of the present invention, one of ordinary skill in the art can propose a plurality of frame mode of the present invention and method for making.Therefore following embodiment and accompanying drawing are only illustrating of technical scheme of the present invention, and should not be considered as of the present invention all or be considered as restriction or the restriction of technical solution of the present invention.

Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail.

As shown in Figure 1, be the digital core pulse Gauss manufacturing process based on Impulse invariance procedure, the method comprises the following steps:

Step 10 is according to the circuit of simulation Gauss formation system, obtain the differential equation of circuit system input signal f (t) and output signal y (t), the differential equation is derived by frequency-domain analysis, obtain the unit impulse response h (t) of simulation Gaussian Systems;

The circuit of above-mentioned simulation Gauss formation system is the circuit of simulation Sallen-Key wave filter, according to the circuit theory (as shown in Figure 2) of simulation Sallen-Key wave filter, the differential equation of listing between input signal f (t) and output signal y (t) is:

R ²C ²y"(t)+RCy′(t)+y(t)＝2f(t) (1)

With frequency domain analysis, derive the unit impulse response of simulation Gaussian Systems

$f\left(\mathrm{\ω}\right)={\∫}_{-\∞}^{\∞}f\left(t\right)e^{-\mathrm{j\ωt}}\mathrm{dt}---\left(2\right)$

$Y\left(\mathrm{\ω}\right)={\∫}_{-\∞}^{\∞}y\left(t\right)e^{-\mathrm{j\ωt}}\mathrm{dt}---\left(3\right)$

$\frac{d^{n}y\left(t\right)}{{\mathrm{dt}}^n}\stackrel{L}{\↔}j{\mathrm{\ω}}^{n}Y\left(\mathrm{\ω}\right)---\left(4\right)$

According to the frequency response function H (ω) that must simulate Gauss's formation system is:

$H\left(\mathrm{\ω}\right)=\frac{Y\left(\mathrm{\ω}\right)}{F\left(\mathrm{\ω}\right)}=\frac{2}{R^2{C}^2{\left(\mathrm{j\ω}\right)}^2+\mathrm{RCj\ω}+1}---\left(5\right)$

It is carried out to inverse Fourier transform obtains:

$h\left(t\right)=\frac{{2e}^{-{\left(\frac{1}{2\mathrm{FC}}\right)}^t}\sin \left(\frac{\sqrt{B}}{2\mathrm{RC}}\right)t}{\sqrt{3}\mathrm{RC}}u\left(t\right)---\left(6\right)$

The frequency response of step 20 analysis mode Gauss formation system, and according to the spectral range of frequency response, determine the frequency that simulation Gauss formation system is sampled;

Guarantee that sample frequency is greater than 2 times of simulation Gauss formation system frequency response bandwidth, to avoid analog domain that spectral aliasing occurs when numeric field is changed.

Step 30 is converted to numeric field by simulation Gauss formation system by analog domain, obtains the unit impulse response h (n) of digital Gauss's formation system, contains the forming parameter that can adjust waveform width in described impulse response;

The unit impulse response h (n) of described digital Gauss's formation system just in time equals the sampled value of the impulse response h (t) of analog filter, i.e. h (n)=h (t) | _t=nT, T is the sampling period.

$h\left(n\right)=\frac{{2\mathrm{ae}}^{-\frac{a}{2}n}\sin \frac{\sqrt{3}a}{2}n}{\sqrt{3}}u\left(n\right)---\left(7\right)$

Wherein, $\frac{T}{\mathrm{RC}}=a$

Suitable forming parameter in the selected impulse response of step 40, determines the value of RC and T, and according to selected forming parameter value, determines the unit impulse response h (n) of corresponding digital Gauss's formation system;

Step 50 is input to the core pulse signal of digital Gauss's formation system and the unit impulse response of digital Gauss's formation system carries out convolution and computing, realizes digital core pulse Gauss and is shaped, that is:

$y\left(n\right)=f\left(n\right)*h\left(n\right)=\underset{k=-\∞}{\overset{\∞}{\mathrm{\Σ}}}f\left(m\right)h(n-m)---\left(8\right)$

Fig. 3 is the parameter waveform that Gauss pulse is shaped while getting different value.As can be seen from the figure parameter value can affect width and the waveform shape of shaped pulse, in practical application, can select according to actual needs suitable parameter value, to meet different measurement demands.

Although the disclosed embodiment of the present invention as above, the embodiment that described content just adopts for the ease of understanding the present invention, not in order to limit the present invention.Technician in any the technical field of the invention; do not departing under the prerequisite of the disclosed spirit and scope of the present invention; can do any modification and variation what implement in form and in details; but scope of patent protection of the present invention, still must be as the criterion with the scope that appending claims was defined.

Claims (5)

1. the digital core pulse Gauss manufacturing process based on Impulse invariance procedure, is characterized in that, described method comprises:

According to the circuit of simulation Gauss formation system, obtain the differential equation of circuit system input signal and output signal, the differential equation is derived by frequency-domain analysis, obtain the unit impulse response of simulation Gaussian Systems;

The frequency response of analysis mode Gauss formation system, and according to the spectral range of frequency response, determine the frequency that simulation Gauss formation system is sampled;

Simulation Gauss formation system is converted to numeric field with Impulse invariance procedure by analog domain, obtains the unit impulse response of digital Gauss's formation system, in described impulse response, contain the forming parameter that can adjust waveform width;

Select the forming parameter in impulse response, and according to selected forming parameter value, determine the unit impulse response of corresponding digital Gauss's formation system;

To be input to the core pulse signal of digital Gauss's formation system and the unit impulse response of digital Gauss's formation system carries out convolution and computing, realize digital core pulse Gauss and be shaped.

2. the digital core pulse Gauss manufacturing process based on Impulse invariance procedure according to claim 1, is characterized in that, solving in frequency domain of described simulation Gaussian Systems unit impulse response carried out.

3. the digital core pulse Gauss manufacturing process based on Impulse invariance procedure according to claim 1, is characterized in that, the described frequency that simulation Gauss formation system is sampled is greater than 2 times of simulation Gauss formation system frequency response bandwidth.

4. the digital core pulse Gauss manufacturing process based on Impulse invariance procedure according to claim 1, is characterized in that, described forming parameter affects width and the waveform shape of shaped pulse, and parameter value is less, and waveform is wider.

5. the digital core pulse Gauss manufacturing process based on Impulse invariance procedure according to claim 1, it is characterized in that, described Impulse invariance procedure is: make the unit impulse response of digital Gauss's formation system equal to simulate the sampled value of Gauss's formation system unit impulse response, thereby obtain the unit impulse response of digital Gauss's formation system.