CN105277929A - Flapping frequency measurement method based on carrier phase doppler - Google Patents

Abstract

The invention provides an insect flapping frequency measurement method based on microwave. The method comprises the steps that 1, a high-resolution waveform processing technology is used to process radar echo, so as to realize one-dimensional high-resolution imaging; 2, for multi-frame one-dimensional high-resolution imaging, accumulating is carried out to determine the distance unit of an insect; 3, insect echo is extracted along slow time; 4, insect body echo is removed from the insect echo to acquire wing echo; 5, the phase of the wing echo of the insect is extracted; and 6, Fourier analysis is used to acquire the phase spectrum and the difference phase spectrum of the wing echo of the insect, and the flapping frequency of the insect is acquired through comparative analysis. The method can be used to accurately measure the flapping frequency of the insect.

Description

A kind of frequency measurement method of fluttering its wings up and down based on carrier phase micro-doppler

Technical field

The invention belongs to radar high precision vibration measurement technique field, be specifically related to a kind of frequency measurement method of fluttering its wings up and down based on carrier phase micro-doppler.

Background technology

The insect that entomological radar migrates in the air by launching a branch of electromagnetic wave directive, polypide (having the character similar to raindrop) causes electromagnetic signal to reflect to surrounding, part reflected signal is received by radar, utilize the direction finding and ranging function of radar, the orientation of insect communities can be calculated, highly, the parameter such as displacement and population density, can be the behaviouristics parameter obtaining insect high-altitude flight and new research means is provided, Migrating Insects is impelled to develop into quantitative test by qualitative examination, and have more cognitive to the fly way of insect and immigration pattern, expand the breadth and depth of Migrating Insects research field.From confirming that aerial unknown object that radar finds is for after migrating property insect first, entomologists all over the world utilize entomological radar to carry out extensive research to migrating property insect.The development of entomological radar mainly experienced by two stages, the first stage be mainly used in macroscopical worm group migrate phenomenon observation, subordinate phase is then achieve the extraction to behavioral parameters such as worm swarming line height, population density, sense of displacement, rates of displacement.

Migrate be insect in long-term evolution to the adaptive strategy that environmental change is made, to guarantee that its population colonization is maintained.In order to clear and definite aerial insect community structure, caste/kind between species relationship, insect and natural enemy the problem such as coevolution relation, and analyse in depth Migrating Insects Ecology mechanism and set up the early stage precisely pre-alarming system of insect pest, kind identification is a key difficult problem urgently to be resolved hurrily.Want the kind accurately knowing Migrating Insects, the biological parameter of necessary Obtaining Accurate insect high-altitude flight, as frequency etc. of fluttering its wings up and down.Migrating property insect has the features such as small, high-altitude flight at night, and under the state of migrating, traditional research means all cannot the frequency of fluttering its wings up and down of Obtaining Accurate insect, thus can not the structure of community of the aerial worm group of automatic decision.

Summary of the invention

In view of this, the object of this invention is to provide a kind of frequency measurement method of fluttering its wings up and down based on carrier phase micro-doppler, the method uses radar to observe Migrating Insects, then based on carrier phase Doppler modulation theory, radar return is analyzed, thus accurately obtain the frequency of fluttering its wings up and down of targeted insect.

Insect based on microwave flutters its wings up and down the measuring method of frequency, comprises the steps:

Step one, utilizes high-resolution waveform processing technical finesse radar return, realizes one dimension high-resolution imaging, thus insect and other target is distinguished in distance.

Step 2, accumulate for multiframe one dimension high-resolution imaging, improve the SNR (signal to noise ratio (S/N ratio)) of insect target image, then for the result estimation insect of accumulation and the distance of radar, from one-dimensional range profile, find out the peak value of corresponding insect according to described distance, thus determine the range unit at insect place.

Step 3, due within of short duration integration time, insect can not fly a range unit, therefore can extract echo from insect according to the range unit determined in previous step along the slow time.

Step 4, removes the echo of polypide from the echo of insect, obtains the echo of wing, specific as follows:

When the ratio A/ λ of insect wing amplitude and radar wavelength is larger, described echo is deducted the average of echo, obtain the echo of wing;

When the ratio A/ λ of insect wing amplitude and radar wavelength is less, go out the circle at the fan-shaped track place of rotating vector in described echo based on least square fitting, described echo is deducted the vector of the center of circle representative of this circle, obtain the echo of wing.

Step 5, extracts the phase place of insect wing echo.

Step 6, utilize Fourier analysis to obtain phase frequency spectrum and the differential phase frequency spectrum of insect wing echo, comparative analysis obtains the frequency of fluttering its wings up and down of insect.

The present invention has following beneficial effect:

The present invention is that a kind of insect based on microwave flutters its wings up and down frequency measurement method, for the frequency of fluttering its wings up and down accurately measuring high-altitude Migrating Insects provides a kind of effective means.Be conducive to clear and definite aerial insect community structure, caste/kind between species relationship, insect and natural enemy the problem such as coevolution relation, thus analyse in depth Migrating Insects Ecology mechanism and set up the early stage accurate pre-alarming system of insect pest.

Accompanying drawing explanation

Fig. 1 is the vector representation of echo from insect.

Fig. 2 be insect flutter its wings up and down amplitude different from radar wavelength ratio time radar return real part imaginary part represent; Wherein in Fig. 2 (a), ratio is that in 0.5, Fig. 2 (b), ratio is 0.125.

Fig. 3 utilizes this algorithm to extract insect to flutter its wings up and down the flow process of frequency.

Fig. 4 is experiment scene schematic diagram; Wherein Fig. 4 (a) geometrized structure graph, Fig. 4 (b) is for being pasted onto the insect on foam.

Fig. 5 is experiment scene figure.

Fig. 6 is the outward appearance of three-spotted plusia and the spectrogram of radargrammetry gained; Wherein Fig. 6 (a) outward appearance that is three-spotted plusia, Fig. 6 (b) is the phase frequency spectrum of wing echo, the differential phase frequency spectrum that Fig. 6 (c) is wing echo.

Fig. 7 is the outward appearance of triangle glass geometrid moth and the spectrogram of radargrammetry gained; Wherein Fig. 7 (a) is the outward appearance of triangle glass geometrid moth, and Fig. 7 (b) is the phase frequency spectrum of wing echo, the differential phase frequency spectrum that Fig. 7 (c) is wing echo.

Fig. 8 is the outward appearance of withered leaf noctuid and the spectrogram of radargrammetry gained; Wherein Fig. 8 (a) outward appearance that is withered leaf noctuid, Fig. 8 (b) is the phase frequency spectrum of wing echo, the differential phase frequency spectrum that Fig. 8 (c) is wing echo.

Fig. 9 is the outward appearance of black cutworm and the spectrogram of radargrammetry gained; Wherein Fig. 9 (a) outward appearance that is black cutworm, Fig. 9 (b) is the phase frequency spectrum of wing echo, the differential phase frequency spectrum that Fig. 9 (c) is wing echo.

Embodiment

To develop simultaneously embodiment below in conjunction with accompanying drawing, describe the present invention.

For the linear frequency modulation broadband waveform of radar transmitted pulse system, its transmitted waveform can be written as:

s _T(t)＝cos(2πf _ct+πrt ²+φ ₀)(1)

Wherein, f _cfor signal carrier frequency, r is the frequency modulation rate of linear FM signal, φ ₀for the first phase transmitted.Insect through vertically flying over radar beam is modulated and after intermediate frequency process, echoed signal becomes:

s _I(t,n)＝ρ _bexp[-jπr(t-τ′ _n) ²+2πf _cτ′ _n+φ1]+

(2)

ρ _wexp[-jπr(t-τ″ _n) ²+2πf _cτ″ _n+φ ₂]

Wherein, ρ _b, ρ _wbe respectively the scattering amplitude of insect body and wing, the pulse of n representation signal, φ ₁and φ ₂be signal residual phase, τ ' _nwith τ " _nrepresent the echo time delay of insect body and wing:

${\mathrm{\τ}}_n^{\′}=\frac{2}{c}{R}_b\left({\mathrm{\τ}}_n^{\′}\right)---\left(3\right)$

${\mathrm{\τ}}_n^{\′\′}=\frac{2}{c}{R}_w\left({\mathrm{\τ}}_n^{\′\′}\right)---\left(4\right)$

Wherein, c is the light velocity, R _b(τ ' _n), R _w(τ " _n) represent the distance of insect body and wing and radar respectively.Then utilize pulse compression technique to realize high resolution range, the signal after pulse compression can be expressed as:

s _r(t,n)＝ρ _bsinc[πB(t-τ′ _n)]exp[j(2πf _cτ′ _n+φ ₁)]+

(5)

ρ _wsinc[πB(t-τ″ _n)]exp[j(2πf _cτ″ _n+φ2)]

Consider that radar resolution is not enough to tell insect body and wing, and sinc function has impact characteristics, its impact in analysis below, will be ignored, and can by τ ' _nwith τ " _nregard τ as _n, then formula (5) is reintegrated:

$\begin{array}{c}{s}_r\left({\mathrm{\τ}}_n\right)={\mathrm{\ρ}}_b\exp \[{\mathrm{j\φ}}_b\left({\mathrm{\τ}}_n\right)\]+{\mathrm{\ρ}}_w\exp \[{\mathrm{j\φ}}_w\left({\mathrm{\τ}}_n\right)\]\\ ={\mathrm{\ρ}}_b\exp \[j\frac{4\mathrm{\π}}{\mathrm{\λ}}{R}_b\left({\mathrm{\τ}}_n\right)+{\mathrm{j\φ}}_1\]+{\mathrm{\ρ}}_w\exp \[j\frac{4\mathrm{\π}}{\mathrm{\λ}}{R}_w\left({\mathrm{\τ}}_n\right)+{\mathrm{j\φ}}_w\]\end{array}---\left(6\right)$

Wherein, λ is radar wavelength, R _b(τ _n) and R _w(τ _n) can be written as:

R _b(τ _n)＝R _c1+vτ _n＝R _c1+vnT(7)

R _w(τ _n)＝R _c2+vτ _n+Asin(2πf _vτ _n)

(8)

＝R _c2+vτ _n+Asin(2πf _vnT)

Wherein, R _c1, R _c2be respectively the distance in fact of insect body, wing and radar, v is the radial flight speed of insect, and T is pulse-recurrence time, and n is pulse number, A and f _vfor Oscillation Amplitude and the vibration frequency of insect wing.When considering measurement, insect passes perpendicularly through radar beam, and integration time is short, and thus the radial velocity of insect can be ignored, i.e. v ≈ 0.

By formula (6) vector representation, obtain Fig. 1, visible echo s _r(τ _n) superposition of direct current vector sum rotating vector can be regarded as, wherein direct current vector represents the polypide echo of insect, and rotating vector represents the wing echo of insect.Extracting the flutter its wings up and down key of frequency of insect based on carrier phase is from s _r(τ _n) in isolate rotating vector, then its phase place is analyzed, thus extracts the frequency of fluttering its wings up and down of insect.Set forth the embodiment removing insect body echo in two kinds of situation as follows:

1) when insect wing amplitude and radar wavelength ratio A/ λ comparatively large (being more than or equal to 1/2) time, for specific insect, namely, when radar wavelength is less, as shown in Fig. 2 (a), the vector representing insect wing echo can rotate over 1 and enclose even multi-turn.Such as, when A/ λ=0.5, rotating vector can rotate 2 circles.Now the mean approximation of echo equals the direct current vector representing insect body echo, i.e. the center of rotating vector.By deducting the average of echo, the echo of insect body can be removed.

2) as the ratio A/ λ less (being less than 1/2) of insect wing amplitude and radar wavelength, for specific insect, namely, when radar wavelength is larger, as shown in Fig. 2 (b), the rotational trajectory representing the vector of insect wing echo is fan-shaped (being less than 1 circle).Such as, when A/ λ=0.125, rotating vector can half rotation.Mean approximation now cannot be utilized to obtain the direct current vector of insect body echo.Solution is the circle at the fan-shaped track place going out rotating vector based on least square fitting, and the vector of the center of circle representative of this circle can be approximately the echo of insect body, deducts this vector, can remove the echo of insect body.

After removing insect body echo, obtaining signal is:

$s_w\left({\mathrm{\τ}}_n\right)={\mathrm{\ρ}}_w\exp \left\{j\[\frac{4\mathrm{\π}A\sin \left(2{\mathrm{\πf}}_v{\mathrm{\τ}}_n\right)}{\mathrm{\λ}}+\mathrm{\φ}\]\right\}---\left(9\right)$

Wherein, φ is total residual phase.The vibration phase that phase place can obtain insect wing is got to this signal, then Fourier analysis is carried out to phase place, the frequency of fluttering its wings up and down of insect can be obtained.Consider thoroughly, to cause still there is direct current component in phase frequency spectrum when removing the direct current echo of insect, and affect final insect and to flutter its wings up and down the extraction of frequency, difference can be got to phase place, thus removal direct current, be convenient to insect and flutter its wings up and down the extraction of frequency.

Therefore, the invention provides a kind of insect based on microwave and to flutter its wings up and down the measuring method of frequency, as shown in Figure 3, comprise the steps:

Step one, utilizes high-resolution waveform processing technical finesse radar return, realizes one dimension high-resolution imaging, thus insect and other target is distinguished in distance.

Step 2, accumulate for multiframe one dimension high-resolution imaging, improve the SNR (signal to noise ratio (S/N ratio)) of insect target image, then for the result estimation insect of accumulation and the distance of radar, from one-dimensional range profile, find out the peak value of corresponding insect according to described distance, thus determine the range unit at insect place.

Step 3, due within of short duration integration time, insect can not fly a range unit, therefore can extract echo from insect according to the range unit determined in previous step along the slow time.

Step 4, removes the echo of polypide from the echo of insect, obtains the echo of wing, specific as follows:

When insect wing amplitude and radar wavelength ratio A/ λ comparatively large (being more than or equal to 1/2) time, described echo is deducted the average of echo, obtains the echo of wing;

As the ratio A/ λ less (being less than 1/2) of insect wing amplitude and radar wavelength, the circle at the fan-shaped track place of rotating vector in described echo is gone out based on least square fitting, described echo is deducted the vector of the center of circle representative of this circle, obtain the echo of wing.

Step 5, extracts the phase place of insect wing echo.

Step 6, utilize Fourier analysis to obtain phase frequency spectrum and the differential phase frequency spectrum of insect wing echo, comparative analysis obtains the frequency of fluttering its wings up and down of insect.

Embodiment:

In order to verify correctness of the present invention, carried out related experiment, the signal of experiment geometry and experiment scene are respectively as shown in Figure 4 and Figure 5.This experiment is carried out in microwave dark room, and radar adopts observed pattern vertically upward, and insect is pasted onto on the foam of suspension.The correlation parameter of this radar is as follows:

Table 1 radar parameter

Measure the frequency of fluttering its wings up and down of three-spotted plusia, triangle glass geometrid moth, withered leaf noctuid and black cutworm during experiment, insects outward appearance and gained spectrogram are respectively as shown in Fig. 6, Fig. 7, Fig. 8 and Fig. 9.The insect recorded by stroboscope frequency of fluttering its wings up and down contrasts as true value, and statistical measurements is as follows:

By the result that contrast radar and stroboscope record, can see that the frequency of fluttering its wings up and down utilizing radargrammetry vertically to fly over the insect of wave beam is feasible, and precision is higher.

In sum, these are only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (2)

1. a measuring method for frequency of fluttering its wings up and down based on the insect of microwave, is characterized in that, comprise the steps:

Step one, utilizes high-resolution waveform processing technical finesse radar return, realizes one dimension high-resolution imaging;

Step 2, accumulates for multiframe one dimension high-resolution imaging, then for the result estimation insect of accumulation and the distance of radar, finds out the peak value of corresponding insect, determine the range unit at insect place according to described distance from one-dimensional range profile;

Step 3, extracts echo from insect according to the range unit determined in step 2 along the slow time;

Step 4, removes the echo of polypide from the echo of insect, obtains the echo of wing, specific as follows:

When the ratio A/ λ of insect wing amplitude and radar wavelength is larger, described echo is deducted the average of echo, obtain the echo of wing;

When the ratio A/ λ of insect wing amplitude and radar wavelength is less, go out the circle at the fan-shaped track place of rotating vector in described echo based on least square fitting, described echo is deducted the vector of the center of circle representative of this circle, obtain the echo of wing;

Step 5, extracts the phase place of insect wing echo;

Step 6, utilize Fourier analysis to obtain phase frequency spectrum and the differential phase frequency spectrum of insect wing echo, comparative analysis obtains the frequency of fluttering its wings up and down of insect.

2. a kind of insect based on microwave flutters its wings up and down the measuring method of frequency according to claim 1, it is characterized in that, when ratio A/ λ is more than or equal to 1/2, then assert that ratio A/ λ is comparatively large, when ratio A/ λ is less than 1/2, then assert that ratio A/ λ is less.