CN104601143A - Numerical analysis method of anti-aliasing filtering circuit in time domain - Google Patents
Numerical analysis method of anti-aliasing filtering circuit in time domain Download PDFInfo
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- CN104601143A CN104601143A CN201410826106.7A CN201410826106A CN104601143A CN 104601143 A CN104601143 A CN 104601143A CN 201410826106 A CN201410826106 A CN 201410826106A CN 104601143 A CN104601143 A CN 104601143A
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Abstract
The invention discloses a numerical analysis method of an anti-aliasing filtering circuit in a time domain. The method comprises the steps of A, creating a current transfer equation set of nodes according to the kirchhoff current law and based on the anti-aliasing filtering circuit; B, performing formal transformation for the transfer equation set, wherein the function relation between an input signal and an output signal can be shown as a second order differential equation; C, solving the equation by the numerical differentiation method to obtain a numerical model of the anti-aliasing filtering circuit. According to the method, a novel method for studying the numerical model of the anti-aliasing filtering circuit in the time domain is proposed, which can perform filtering, and pulse width and amplitude analysis and control for an output pulse signal of a front end pulse detector within the time domain; therefore, the digital model is of practical guide significance for the design and test of filtering and amplitude and width analyzing circuits of an actual pulse signal; the working efficiency of the actual circuit design can be increased, and the target selectivity of an electronic device is improved.
Description
Technical field
The present invention relates to the treatment technology to front end pulse detector output signal in time domain, the numerical analysis method of especially pulse signal filtering process.
Background technology
The physiological and pathological information extracting human body from pulse wave signal, as the foundation of clinical diagnosis and treatment, is always subject to the attention of China and foreign countries' medical circle.Pulse wave signal contains a large amount of information with clinical medicine reference significance, and collection accurately and efficiently and analyzing and processing pulse wave signal are to observation physiological pathology of human body information important in inhibiting.But, grasp TCM pulse diagnosis skill difficulty comparatively large, not only need the guidance of well-known doctor to teach, more need long experience accumulation.Can see, along with the development of modern biomedical, by instrument and meter Real-time Obtaining pulse information, can not only accurate Drawing pulse wave, can spectrum analysis be carried out simultaneously.
In measuring system data acquisition, inevitably have high-frequency interferencing signal and be mingled in the middle of useful signal.When the frequency of these signals exceedes the scope of nyquist sampling theorem defined, some uncertain signals can be collected and interference is caused to useful signal, be i.e. signal aliasing.In order to farthest suppress or eliminate aliasing to the impact of dynamic measuring control system data acquisition, need to utilize Anti-aliasing Filter Circuits to be carried out decaying and filtering by unwanted signal.Adopt the Anti-aliasing Filter Circuits of discrete component design, be difficult to accurate selection resistance and electric capacity for filtering parameter, cannot sharp cut-off be realized to interference signal, also not reach higher filtering Q factor.Meanwhile, the drift that discrete component self is intrinsic, also causes the uncertain of filtering parameter.And, adopt discrete component design filter circuit, be not easy to parameter and regulate and system upgrade.Therefore, Anti-aliasing Filter Circuits is carried out digitized processing, study its mathematical filtering model, not only can realize the filtering of interference signal flexibly, and more can overcome the parameter drift that brings because of discrete component design and many drawbacks such as uncertain.
Summary of the invention
The object of this invention is to provide the numerical analysis method of Anti-aliasing Filter Circuits in a kind of time domain, the method overcome because of the discrete component design parameter drift that brings of filter circuit and many drawbacks such as uncertain, and then pulse signal is carried out to the process of filtering, analysis & control in time domain, thus instruct and reference for the design of actual pulse signal filter circuit and test provide.
The invention discloses the numerical analysis method of Anti-aliasing Filter Circuits in a kind of time domain, its step: A, based on Anti-aliasing Filter Circuits, use Kirchhoff's current law (KCL) to set up current delivery equation group between node; B, equation of transfer group are after formal argument, and between input signal and output signal, functional relation can be expressed as second order differential equation; C, utilization numerical differentiation solve this equation, thus obtain the numerical model of Anti-aliasing Filter Circuits.
Tool of the present invention has the following advantages: 1. on system approach, establishes the numerical model in Anti-aliasing Filter Circuits time domain; 2. in circuit function, complete the process of pulse signal anti-aliasing filter, and test the filter result of actual pulse signal by side circuit.
Accompanying drawing explanation
Fig. 1 Anti-aliasing Filter Circuits figure.
The oscillogram of the actual test result of Fig. 2 Anti-aliasing Filter Circuits.
The oscillogram of Fig. 3 actual pulse signal testing result.
Embodiment
The digital value analytical method of Anti-aliasing Filter Circuits in a kind of time domain:
In FIG, according to Kirchhoff's current law (KCL), define respectively
v in,
v x,
v p,
v nwith
v o, then can set up following 3 equation group:
⑴
⑵
⑶
(3) formula formal argument will be carried out:
⑷
(4) formula (2) formula will be substituted into,
⑸
According to " empty short " characteristic of operational amplifier, namely
v n=
v p, (5) formula can be converted to:
⑹
(6) formula formal argument will be carried out, after merging similar terms:
⑺
(7), in formula, get
r 1=
r 2=
r,
r 3=
r 4=
r',
c 1=
c 2=
c, and by input signal
v inbe defined as
x, output signal
v obe defined as
y, then can obtain:
⑻
After merging similar terms,
⑼
After arrangement, (9) formula can be converted to:
⑽
Wherein,
xrepresent input variable
v in,
yrepresent output variable
v o.From form, this equation is a nonhomogeneous second differential equation.Resolve this equation, the numerical relationship model that pulse signal outputs signal after frequency overlapped-resistable filter can be drawn.
Consider discrete feature and the randomness feature of pulse signal self, (10) the process solved of formula can not adopt the method for " general solution-particular solution " to carry out.Which is only applicable to solving of the second differential equation of continuous signal.Therefore, solving of (10) formula is needed to adopt differential numerical method, namely adopts the method for solving of the second differential equation of discrete signal to complete.
After using differential numerical method, (10) formula can be transformed to:
⑾
Decompose after merging:
⑿
Order
, be filtering parameter, after (12) formula merges arrangement,
⒀
Then,
⒁
⒂
⒃
⒄
In sum, pulse signal carries out anti-aliasing filter can call realization by (17) formula recursion, wherein
krepresent the adjustment parameter of filtered output signals, adjustment
kcut-off frequency and the filter effect of output waveform can be set.
The oscillogram of test result as actual in Fig. 2 Anti-aliasing Filter Circuits.
As the oscillogram of Fig. 3 actual pulse signal testing result.
Claims (1)
1. the numerical analysis method of Anti-aliasing Filter Circuits in time domain, its step: A, based on Anti-aliasing Filter Circuits, uses Kirchhoff's current law (KCL) to set up current delivery equation group between node; B, equation of transfer group are after formal argument, and between input signal and output signal, functional relation can be expressed as second order differential equation; C, utilization numerical differentiation solve this equation, thus obtain the numerical model of Anti-aliasing Filter Circuits.
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| CN201410826106.7A CN104601143A (en) | 2014-12-26 | 2014-12-26 | Numerical analysis method of anti-aliasing filtering circuit in time domain |
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| CN201410826106.7A Pending CN104601143A (en) | 2014-12-26 | 2014-12-26 | Numerical analysis method of anti-aliasing filtering circuit in time domain |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109602414A (en) * | 2018-11-12 | 2019-04-12 | 安徽心之声医疗科技有限公司 | A kind of ecg signal data Enhancement Method of multi-angle of view conversion |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5233546A (en) * | 1991-08-14 | 1993-08-03 | Hewlett-Packard Company | Anti-alias filtering apparatus for frequency domain measurements |
| CN102970537A (en) * | 2012-11-18 | 2013-03-13 | 成都锐成芯微科技有限责任公司 | Anti-aliasing low pass filter for video signals |
-
2014
- 2014-12-26 CN CN201410826106.7A patent/CN104601143A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5233546A (en) * | 1991-08-14 | 1993-08-03 | Hewlett-Packard Company | Anti-alias filtering apparatus for frequency domain measurements |
| CN102970537A (en) * | 2012-11-18 | 2013-03-13 | 成都锐成芯微科技有限责任公司 | Anti-aliasing low pass filter for video signals |
Non-Patent Citations (3)
| Title |
|---|
| JAMES KARKI等: "全差分放大器（一）", 《国外电子元器件》 * |
| 李鲜等: "PCM语音编码系统抗混叠滤波器设计", 《中国集成电路》 * |
| 王宇野等: "《电子技术（双语版）电工学（下册）》", 31 October 2013 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109602414A (en) * | 2018-11-12 | 2019-04-12 | 安徽心之声医疗科技有限公司 | A kind of ecg signal data Enhancement Method of multi-angle of view conversion |
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Application publication date: 20150506 |