CN106374878B - A kind of digital trapper filtering method reducing high frequency distortion - Google Patents
A kind of digital trapper filtering method reducing high frequency distortion Download PDFInfo
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- CN106374878B CN106374878B CN201610728087.3A CN201610728087A CN106374878B CN 106374878 B CN106374878 B CN 106374878B CN 201610728087 A CN201610728087 A CN 201610728087A CN 106374878 B CN106374878 B CN 106374878B
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H17/00—Networks using digital techniques
- H03H17/02—Frequency selective networks
- H03H17/0248—Filters characterised by a particular frequency response or filtering method
- H03H17/025—Notch filters
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H2222/00—Indexing scheme relating to digital filtering methods
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Abstract
The invention discloses a kind of digital trapper filtering methods for reducing high frequency distortion comprising the steps of: determines the target center frequency of notch filter；According to the target center frequency of notch filter, a digital notch filter model is established；It determines the relationship of notch filter input and output according to digital notch filter model in missile-borne computer, completes the foundation of digital trapper.The present invention directly generates the digital filter model realized convenient for missile-borne computer according to notch filter centre frequency, it avoids being distorted since notch filter centre frequency and missile-borne computer resolve frequency amplitude characteristic caused by, while guaranteeing that filter has certain amplitude attenuation effect in high band.
Description
Technical field
The present invention relates to trapper technical field of filtering, and in particular to a kind of digital trapper filter for reducing high frequency distortion
Wave method.
Application field of the invention is the inhibition of tactical weapon automatic pilot high-frequency noise, it is characterized in that avoiding due to trap
Filter centre frequency and missile-borne computer resolve frequency amplitude characteristic caused by and are distorted, and improve automatic pilot to high frequency
The inhibitory effect of noise.
Background technique
High-frequency noise inhibition is an important content of tactical weapon Autopilot Design, can improve system stability,
And good working environment is provided for the affiliated subsystem of automatic pilot and single machine, guarantee system reliability service.
The source of automatic pilot high-frequency noise is mainly the vibration of aircraft natural resiliency, subsystem and single machine own resonance
Deng having the characteristics that amplitude is big, frequency is high.
Notch filter is generallyd use in Autopilot Design inhibits high-frequency noise.Common notch filter design stream
Journey is to determine notch filter centre frequency according to target frequency, forms analog filter model；Bilinear transformation is used again
Analog filter model is converted into digital filter model, is realized convenient for missile-borne computer.
The major defect of this design method is the process that analog filter model is converted to digital filter model
In, since notch filter centre frequency and missile-borne computer resolve frequency relatively, lead to notch filter amplitude characteristic
Exist in high band and be distorted, influences filter effect.
Summary of the invention
The purpose of the present invention is to provide a kind of digital trapper filtering methods for reducing high frequency distortion, are filtered according to trap
Wave device centre frequency directly generates the digital filter model realized convenient for missile-borne computer, avoids due in notch filter
Frequency of heart and missile-borne computer resolve frequency amplitude characteristic caused by and are distorted, while guaranteeing that filter has one in high band
Tentering value attenuating.
In order to achieve the above object, the invention is realized by the following technical scheme: a kind of to reduce the digital of high frequency distortion
Trapper filtering method, its main feature is that comprising the steps of:
Determine the target center frequency of notch filter；
According to the target center frequency of notch filter, a digital notch filter model is established；
The relationship of notch filter input and output is determined according to digital notch filter model in missile-borne computer,
Complete the foundation of digital trapper.
The digital notch filter model is expressed as:
a1=-2cos (2 π f1T)
a2=-2cos (2 π f2T)
In formula, y indicates notch filter output, and u indicates notch filter input, and ρ indicates notch filter parameter, f1Table
Show notch filter centre frequency, f2Indicate notch filter parameter, T indicates system communication cycle, and the relationship of the domain z and frequency domain is
Z=ejωT, ω is the frequency of input signal, and j is imaginary number, G2(z-1) in ω → 0 gain be the π of 1, ω → 2 f1Shi Zengyi is 0, ω
Gain is less than 1 when → π/T.
The notch filter input and the relationship of output is expressed as:
Y (k)=- A1y(k-1)-A2y(k-2)+B0u(k)+B1u(k-1)+B2u(k-2)
In formula, y (k) indicates the output of kT moment notch filter, and y (k-1) indicates (k-1) T moment notch filter
The output of device, y (k-2) indicate the output of (k-2) T moment notch filter, and u (k) indicates kT moment notch filter
The input of device, u (k-1) indicate the input of (k-1) T moment notch filter, and u (k-2) indicates (k-2) T moment trap
The input of filter, A1, A2, B0, B1, B2Indicate notch filter parameter, A1=(1- ρ) × a2, A2=1-2 ρ, a1=-2cos (2 π f1T), a2=-
2cos(2πf2T), T indicates that system communication cycle, ρ indicate notch filter parameter, f1Indicate notch filter centre frequency, f2
Indicate notch filter parameter.
A kind of digital trapper filtering method for reducing high frequency distortion of the present invention has following excellent compared with prior art
Point: the present invention directly generates digital filter model according to notch filter centre frequency, simplifies according to filter center
The analog filter model of Frequency Design, then be converted to by analog filter model the design cycle of digital model；This hair
It is bright to avoid being distorted since filter centre frequency and missile-borne computer resolve frequency amplitude characteristic caused by；Tradition is solved to fall into
The wave filter problem on the weak side in the high band filter effect for being higher than centre frequency, guarantees that filter has a tentering in high band
It is worth attenuating.
Detailed description of the invention
Fig. 1 is a kind of flow chart for the digital trapper filtering method for reducing high frequency distortion of the present invention；
Before Fig. 2 is the digital notch filter being converted in the prior art using bilinearity changing method and converted
Analog notch filter frequency Character Comparison curve；
Fig. 3 is in the embodiment of the present invention, and centre frequency is the digital notch filter frequency characteristic curve of 120Hz.
Specific embodiment
The present invention is further elaborated by the way that a preferable specific embodiment is described in detail below in conjunction with attached drawing.
As shown in Figure 1, a kind of digital trapper filtering method for reducing high frequency distortion comprising the steps of:
S1, the target center frequency for determining notch filter.
The centre frequency of notch filter directly affects the calculating of digital notch filter parameter, according to notch filter
In the amplitude attenuation demand of high band, the parameter of digital notch filter is selected.
S2, the target center frequency according to notch filter establish a digital notch filter model.
Digital notch filter model is expressed as:
a1=-2cos (2 π f1T)
a2=-2cos (2 π f2T)
In formula, y indicates notch filter output, and u indicates notch filter input, and ρ indicates notch filter parameter, f1Table
Show notch filter centre frequency, f2Indicate notch filter parameter, T indicates system communication cycle, and the relationship of the domain z and frequency domain is
Z=ejωT, ω is the frequency of input signal, and j is imaginary number, G2(z-1) in ω → 0 gain be the π of 1, ω → 2 f1Shi Zengyi is 0, ω
Gain is less than 1 when → π/T.
Notch filter does not decay to low-band signal amplitude, to target frequency signal complete attenuation, believes high band
Number amplitude has certain decaying, has ideal frequency characteristic in whole frequency range.
S3, the pass of notch filter input and output is determined according to digital notch filter model in missile-borne computer
System, completes the foundation of digital trapper.
Notch filter input and the relationship of output are expressed as:
Y (k)=- A1y(k-1)-A2y(k-2)+B0u(k)+B1u(k-1)+B2u(k-2)
In formula, y (k) indicates the output of kT moment notch filter, and y (k-1) indicates the filter of (k-1) T moment trap
The output of wave device, y (k-2) indicate the output of (k-2) T moment notch filter, and u (k) indicates kT moment trap
The input of filter, u (k-1) indicates the input of (k-1) T moment notch filter, when u (k-2) indicates (k-2) T
Carve the input of notch filter, A1, A2, B0, B1, B2Indicate notch filter parameter, A1=(1- ρ) × a2, A2=1-2 ρ, a1=-2cos (2 π f1T), a2=-
2cos(2πf2T), T indicates that system communication cycle, ρ indicate notch filter parameter, f1Indicate notch filter centre frequency, f2
Indicate notch filter parameter.
Concrete application: as shown in Figures 2 and 3, it is 400Hz that missile-borne computer, which resolves frequency, figure it is seen that existing
There is the notch filter centre frequency being converted in technology to become 96.2Hz, is not inconsistent with target center frequency 120Hz, trap filter
Wave device exists in high band to be distorted；From figure 3, it can be seen that notch filter of the invention is in the target at frequency of heart 120Hz
Amplitude attenuation is 140dB, and the amplitude attenuation for being greater than 120Hz high-frequency signal to frequency is not less than 5.56dB, is illustrated of the invention effective
It solves the problems, such as notch filter high frequency distortion, while guaranteeing that notch filter has certain amplitude attenuation effect in high band.
The major parameter for determining notch filter performance is f1、f2And ρ.In notch filter design process, basis first
Notch filter centre frequency determines f1, by taking centre frequency shown in Fig. 3 is the notch filter of 120Hz as an example, f1Take 120；f2
Size determine notch filter in the filter effect of high band, generally take f2<f1, f2Smaller notch filter is in high band
Amplitude attenuation is bigger, the corresponding notch filter f of Fig. 32Take 100；The size of ρ determines the width of notch filter, the bigger trap of ρ
Filter is wider, and the corresponding notch filter ρ of Fig. 3 takes 0.27.
By adjusting f1, f2With the size of ρ, can must have the digital notch filter model of ideal frequency characteristic, and root
It is realized on missile-borne computer according to notch filter input and the relationship of output.
It is discussed in detail although the contents of the present invention have passed through above preferred embodiment, but it should be appreciated that above-mentioned
Description is not considered as limitation of the present invention.After those skilled in the art have read above content, for of the invention
A variety of modifications and substitutions all will be apparent.Therefore, protection scope of the present invention should be limited to the appended claims.
Claims (2)
1. a kind of digital trapper filtering method for reducing high frequency distortion, which is characterized in that comprise the steps of:
Determine the target center frequency of notch filter；
According to the target center frequency of notch filter, a digital notch filter model is established；
The relationship of notch filter input and output is determined according to digital notch filter model in missile-borne computer, is completed
The foundation of digital trapper；
The digital notch filter model is expressed as:
a1=-2cos (2 π f1T)
a2=-2cos (2 π f2T)
In formula, y indicates notch filter output, and u indicates notch filter input, and ρ indicates notch filter parameter, f1It indicates to fall into
Wave filter centre frequency, f2The relationship of expression notch filter parameter, T expression system communication cycle, the domain z and frequency domain is z=ej ωT, ω is the frequency of input signal, and j is imaginary number, G2(z-1) in ω → 0 gain be the π of 1, ω → 2 f1Shi Zengyi is 0, ω → π/T
Shi Zengyi is less than 1.
2. digital trapper filtering method as described in claim 1, which is characterized in that the notch filter input with
The relationship of output is expressed as:
Y (k)=- A1y(k-1)-A2y(k-2)+B0u(k)+B1u(k-1)+B2u(k-2)
In formula, y (k) indicates the output of kT moment notch filter, and y (k-1) indicates the output of (k-1) T moment notch filter,
Y (k-2) indicates the output of (k-2) T moment notch filter, and u (k) indicates the input of kT moment notch filter, u (k-1) table
Show the input of (k-1) T moment notch filter, u (k-2) indicates the input of (k-2) T moment notch filter, A1, A2, B0, B1,
B2Indicate notch filter parameter, A1=(1- ρ) × a2, A2=1-2 ρ, a1=-2cos (2 π f1T), a2=-2cos (2 π f2T), T indicates that system communication cycle, ρ indicate trap
Filter parameter, f1Indicate notch filter centre frequency, f2Indicate notch filter parameter.
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| CN111541437A (en) * | 2020-05-13 | 2020-08-14 | 上海航天控制技术研究所 | Filter algorithm suitable for elastic frequency time-varying characteristic |
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| CN1758536A (en) * | 2004-10-09 | 2006-04-12 | 深圳迈瑞生物医疗电子股份有限公司 | Industry frequency automatic tracking filtering method and device |
| CN102394664A (en) * | 2011-11-04 | 2012-03-28 | 物联微电子(常熟)有限公司 | Frequency modulation reception device capable of automatic interference elimination and method |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1758536A (en) * | 2004-10-09 | 2006-04-12 | 深圳迈瑞生物医疗电子股份有限公司 | Industry frequency automatic tracking filtering method and device |
| CN102394664A (en) * | 2011-11-04 | 2012-03-28 | 物联微电子(常熟)有限公司 | Frequency modulation reception device capable of automatic interference elimination and method |
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| "IIR数字滤波器的设计及FPGA实现";陈晓勇;《中国科技信息》;20061115(第22期);第83-85页 |
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