CN103580646B - A kind of method for estimating analog filter frequency response characteristic - Google Patents

Abstract

The present invention method for estimating analog filter frequency response characteristic, by analog filter is connected with analog-digital converter, input at an analog-digital converter input and analog filter is respectively fed to sinusoidal signal, input at another one analog-digital converter sends into cosine signal, and the sinusoidal signal of feeding is identical with the frequency of cosine signal, signal after again analog-digital converter being quantified carries out cross-correlation and is averaging, by calculating amplitude-frequency response and the phase-frequency response obtaining analog filter, so can be accurate, quickly determine amplitude-frequency characteristic and the phase-frequency characteristic of analog filter.

Description

A kind of method for estimating analog filter frequency response characteristic

Technical field

The invention belongs to wave filter technology field, more specifically say, relate to a kind of method for estimating analog filter frequency response characteristic.

Background technology

Wave filter is a kind of device for eliminating jamming incoherent signal, and through filtration, input or output are obtained pure alternating current, and every device having the ability to carry out signal processing can become wave filter.Modern age telecommunication equipment and all kinds of control system in, wave filter application extremely wide；In all of electronic unit, wave filter employs up to, and technology is the most complicated.The good and bad quality directly determining product of wave filter, therefore, research and production to wave filter are always taken seriously.

Analog filter can be divided into passive and active filter.Passive filter is mainly made up of passive element resistance, inductance and electric capacity.Active filter is mainly made up of integrated transporting discharging, resistance and electric capacity, has without the advantage such as inductance, volume be little, lightweight.In general, the exponent number of analog filter or quality factor are more high, and its design is also more complicated.The hardware of analog filter is constituted, such as resistance, electric capacity, inductance or integrated transporting discharging etc., is all highly prone to aging etc. the impact of environment, manufacturing process and time, thus causing the uncertainty of its parameter.

Filter frequency is estimated to suffer from important application in a lot of fields, as signal processing, communication, control and system model set.It is generally adopted by by tested wave filter is inputted a pumping signal, by output signal sampling and FFT, it is thus achieved that wave filter is corresponding to the frequency response of different frequent points, pumping signal can be broadband signal, such as noise signal, it is also possible to be narrow band signal, such as sinusoidal signal.In practical application, pumping signal specifically includes that tone signal, swept-frequency signal, multi-tone signal and pulse signal etc., and wherein comparatively conventional with tone signal and multi-tone signal, its reason is that generation is fairly simple, and easy property performance period.Pumping signal after over-sampling has needed FFT computing to obtain the amplitude corresponding to different frequent points and phase value.But, FFT computing is typically complex, it is necessary to the consuming regular hour just can complete, and when particularly FFT counts bigger, time loss becomes apparent from, and data processing amount also can substantially increase simultaneously.

Summary of the invention

It is an object of the invention to overcome the deficiencies in the prior art, it is provided that a kind of method for estimating analog filter frequency response characteristic, it is possible to accurately, quickly determine amplitude-frequency characteristic and the phase-frequency characteristic of analog filter.

For achieving the above object, a kind of method for estimating analog filter frequency response characteristic of the present invention, it is characterised in that comprise the following steps:

(1), configure three analog-digital converter ADC, the input of the outfan of analog filter H (s) and an ADC is connected；

(2), sending into frequency at the input of the input of analog filter and the 2nd ADC is f_iSinusoidal signal x_siT (), through analog filter filtered signal x '_siT () is sent to an ADC, it is f that the input at the 3rd ADC sends into frequency_iCosine signal x_ci(t), wherein, i=1,2 ..., N, N is total frequency number；

(3), ADC and the two ADC is quantified after signal carry out cross-correlation, and the result of cross-correlation be averaging obtain signal y_s(f_i), the signal after ADC and the three ADC is quantified carries out cross-correlation, and the result of cross-correlation is averaging obtains signal y_c(f_i)；

(4), by the y in step (3)_s(f_i) and y_c(f_i) calculate the amplitude-frequency response of analog filter respectively | H (f_i) | and phase-frequency response

Wherein, described analog-digital converter ADC adopts same frequency f_s。

The goal of the invention of the present invention is achieved in that

The present invention method for estimating analog filter frequency response characteristic, by analog filter is connected with analog-digital converter, input at an analog-digital converter input and analog filter is respectively fed to sinusoidal signal, input at another one analog-digital converter sends into cosine signal, and the sinusoidal signal of feeding is identical with the frequency of cosine signal, signal after again analog-digital converter being quantified carries out cross-correlation and is averaging, by calculating amplitude-frequency response and the phase-frequency response obtaining analog filter, so can be accurate, quickly determine amplitude-frequency characteristic and the phase-frequency characteristic of analog filter.

Meanwhile, the present invention is for estimating that the method for analog filter frequency response characteristic also has the advantages that

(1), the present invention realize simple in construction, there is low cost performance；

(2), the present invention can accurately, quickly determine amplitude-frequency characteristic and the phase-frequency characteristic of analog filter.

Accompanying drawing explanation

Fig. 1 is that the present invention is for estimating the theory diagram of the method for analog filter frequency response characteristic.

Detailed description of the invention

Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described, in order to those skilled in the art is more fully understood that the present invention.Requiring particular attention is that, in the following description, when perhaps the detailed description of known function and design can desalinate the main contents of the present invention, these descriptions here will be left in the basket.

Embodiment

Fig. 1 is that the present invention is for estimating the theory diagram of the method for analog filter frequency response characteristic.

In the present embodiment, as it is shown in figure 1, the present invention is for the method for estimating analog filter frequency response characteristic, it is characterised in that comprise the following steps:

(1), configure three analog-digital converter ADC, the input of the outfan of analog filter H (s) and an ADC is connected；

(2), sending into frequency at the input of the input of analog filter and the 2nd ADC is f_iSinusoidal signal x_siT (), through analog filter filtered signal x '_siT () is sent to an ADC, it is f that the input at the 3rd ADC sends into frequency_iCosine signal x_ci(t), wherein, i=1,2 ..., N, N is total frequency number.If x_si(t)=sin (2 π f_iT), x_ci(t)=cos (2 π f_iT), the employing rate of three ADC is f_s, then three signals after ADC quantifies are respectively as follows:

x_si(n)=sin (2 π nf_i/fs)(1)

x_ci(n)=cos (2 π nf_i/f_s)(3)

|H(f_i) |,Represent that analog filter H (s) is at frequency f respectively_iThe amplitude at place and phase place, δ (n) represents measurement noise；

(3), ADC and the two ADC is quantified after signal carry out cross-correlation, and the result of cross-correlation be averaging obtain signal y_s(f_i), the signal after ADC and the three ADC is quantified carries out cross-correlation, and the result of cross-correlation is averaging obtains signal y_c(f_i).To in step (2), three signals after ADC quantifies take M sampling sampling point respectively simultaneously and carry out the cross-correlation shown in Fig. 1 and average, obtain following two signals:

$y_s\left(f_i\right)=\frac{1}{M}\underset{n=0}{\overset{M-1}{\mathrm{\Σ}}}{x}_{\mathrm{si}}\left(n\right)x_{\mathrm{si}}^{\′}\left(n\right)---\left(4\right)$

$y_c\left(f_i\right)=\frac{1}{M}\underset{n=0}{\overset{M-1}{\mathrm{\Σ}}}{x}_{\mathrm{ci}}\left(n\right)x_{\mathrm{si}}^{\′}\left(n\right)---\left(5\right)$

Select appropriate M so that for arbitrary f_iValue, all comprises integer x in M sampling sampling point_siIn (n) cycle, assume to measure noise δ (n) all uncorrelated with all of signal, then simultaneously formula (4), two signals in (5) can be reduced to:

$y_s\left(f_i\right)$

In like manner

(4) amplitude-frequency response of analog filter, is calculated respectively by the formula (6) in step (3) and (7) | H (f_i) | and phase-frequency response:

$\left|H\left(f_i\right)\right|=2\sqrt{{y_s}^2\left(f_i\right)+{y_c}^2\left(f_i\right)}---\left(8\right)$

Although above the illustrative detailed description of the invention of the present invention being described; so that those skilled in the art understand the present invention; it is to be understood that; the invention is not restricted to the scope of detailed description of the invention; to those skilled in the art; as long as various changes limit and in the spirit and scope of the present invention determined, these changes are apparent from, and all utilize the innovation and creation of present inventive concept all at the row of protection in appended claim.

Claims (2)

1. the method for estimating analog filter frequency response characteristic, it is characterised in that comprise the following steps:

(1), configure three analog-digital converter ADC, the input of the outfan of analog filter H (s) and an ADC is connected；

(2), sending into frequency at the input of the input of analog filter and the 2nd ADC is f_iSinusoidal signal x_siT (), through the filtered signal x' of analog filter_siT () is sent to an ADC, it is f that the input at the 3rd ADC sends into frequency_iCosine signal x_ci(t), wherein, i=1,2 ..., N, N is total frequency number；Three analog-digital converter ADC all adopt same frequency f_s；

(3), ADC and the two ADC is quantified after signal carry out cross-correlation, and the result of cross-correlation be averaging obtain signal y_s(f_i), the signal after ADC and the three ADC is quantified carries out cross-correlation, and the result of cross-correlation is averaging obtains signal y_c(f_i)；

(4), appropriate M is selected so that for arbitrary f_iValue, all comprises integer x in M sampled point_si(n) cycle, wherein, x_siN () is x_si(t) signal after ADC quantifies；By to the y in step (3)_s(f_i) and y_c(f_i) simplify after calculate the amplitude-frequency response of analog filter respectively | H (f_i) | and phase-frequency response

$\left|H\left(f_i\right)\right|=2\sqrt{{y_s}^2\left(f_i\right)+{y_c}^2\left(f_i\right)}$

2. the method for estimating analog filter frequency response characteristic according to claim 1, it is characterised in that carry out cross-correlation in described step (3) and average method is:

Taking M sampled point, the signal after ADC and the two ADC is quantified carries out cross-correlation and average, obtains signal y_s(f_i):

$y_s\left(f_i\right)=\frac{1}{M}\underset{n=0}{\overset{M-1}{\Σ}}{x}_{si}\left(n\right)x_{si}^{\′}\left(n\right)$

Signal after oneth ADC and the three ADC is quantified carries out cross-correlation and average, obtains signal y_c(f_i):

$y_c\left(f_i\right)=\frac{1}{M}\underset{n=0}{\overset{M-1}{\Σ}}{x}_{ci}\left(n\right)x_{si}^{\′}\left(n\right)$

Wherein, x '_si(n)、x_si(n)、x_ciN () is the signal after three ADC quantify respectively.