CN103852595A - Method for low-altitude wind detection - Google Patents

Abstract

The invention discloses a method for low-altitude wind detection. The method comprises the steps of comparing the frequency of a received backscattering echo which is scattered in different directions on a certain layer with the emission frequency f0 of the backscattering echo so as to obtain the frequency shift amount fd of a signal sent in a certain direction on the layer; calculating the wind speed Vd satisfying the equation (please see the equation in the specification) of each direction on the layer according to f0, fd and propagation speed C; combining the wind speeds of the different directions on the layer by using a vector synthesizing algorithm so as to obtain a three-dimensional vector of the wind speeds on the layer. By means of the method, the three-dimensional vector of low-altitude wind can be rapidly and accurately calculated.

Description

The method that a kind of low latitude wind is surveyed

Technical field

The present invention relates to the system for using the meteor oriented acoustic sounding such as wind speed, wind direction, relate in particular to the method that a kind of low latitude wind is surveyed.

Background technology

In the detection of wind speed and direction, conventional means have anemometer tower, wind profile radar, laser radar, acoustic radar etc.Anemometer tower is complicated owing to installing, and is generally used for point of fixity position installation testing, and it is highly subject to the impact of tower height and limited.Wind profile radar belongs to radio radar, and its frequency transmitting is likely subject to the interference of electromagnetic environment, and it reduces be subject to the impact of ground clutter etc. near detection accuracy in the altitude range on ground, and limitation is larger.Laser radar is the detection of carrying out wind speed with laser, and its result of detection is subject to the impact of visibility larger.

In prior art, do not have method comparatively fast and accurately to carry out the detection of low latitude wind (20～500m) trivector.

Summary of the invention

The object of this invention is to provide the method that a kind of low latitude wind is surveyed, can measure accurately low latitude wind (20～500m) trivector.

The method that low latitude wind is surveyed, the method comprises:

By the frequency f during respectively to the frequency of the backscattering echo of scattering and its transmitting on a certain aspect different directions receiving ₀compare, the signal that acquisition is launched towards a direction is at the frequency shift amount f of this aspect _d;

According to f ₀, f _dwith velocity of propagation C calculate each party in this aspect to wind speed V _d:

Utilize vector composition algorithm that the wind speed of different directions in this aspect is merged, obtain the trivector of wind speed in this aspect.

As seen from the above technical solution provided by the invention, the Doppler shift relatively transmitting by the backscattering echo of sound wave in detection atmosphere comes calculation of wind speed and wind direction, and the method can be carried out the calculating of low latitude wind trivector fast and accurately.

Brief description of the drawings

In order to be illustrated more clearly in the technical scheme of the embodiment of the present invention, below the accompanying drawing of required use during embodiment is described is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, do not paying under the prerequisite of creative work, can also obtain other accompanying drawings according to these accompanying drawings.

The schematic diagram of a kind of sodar system that Fig. 1 provides for the embodiment of the present invention;

The schematic diagram of a kind of antenna that Fig. 2 provides for the embodiment of the present invention;

The process flow diagram of the method that a kind of low latitude wind that Fig. 3 provides for the embodiment of the present invention is surveyed;

The schematic diagram that in a kind of antenna that Fig. 4 a embodiment of the present invention provides, transducer is arranged;

The schematic diagram that in the another kind of antenna that Fig. 4 b embodiment of the present invention provides, transducer is arranged;

A kind of multifrequency coding schematic diagram transmitting that Fig. 5 embodiment of the present invention provides;

The cumulative schematic diagram of a kind of multifrequency that Fig. 6 embodiment of the present invention provides;

The process flow diagram of a kind of signal preprocessing that Fig. 7 embodiment of the present invention provides;

A kind of process flow diagram that calculates one party upward direction spectrum data that Fig. 8 embodiment of the present invention provides;

The process flow diagram of a kind of calculation of wind speed trivector that Fig. 9 embodiment of the present invention provides.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiment.Based on embodiments of the invention, those of ordinary skill in the art, not making the every other embodiment obtaining under creative work prerequisite, belong to protection scope of the present invention.

The present invention carries out the detection of low latitude wind by sodar system, as shown in Figure 1, sodar system mainly comprises: phased array antenna and signal processing host.Signal processing host comprises power supply, digital signal processor (DSP), power amplifier and filter amplifier.As shown in Figure 2, phased array antenna is made up of 64 piezoelectric ceramic transducers with transmitting-receiving reciprocal characteristics, 64 transducers are with 8 × 8 mode close-packed arrays, and the half-wavelength that single transducer bore is corresponding with the centre frequency that transmits is suitable, and antenna cross sectional shape is square.Wherein, the transducer phase value of each row or row is identical, and the phase differential amount of moving of the transducer of adjacent two rows or two row equates, be approximately 45 degree, thereby, can form 4 of all directions slant beam, slant beam misalignment vertical axis is approximately 15 degree.

The present embodiment by reference to the accompanying drawings 3, the process of sodar system being carried out to low latitude wind detection is described in detail, and as shown in Figure 2, mainly comprises the steps:

Step 301, signal processing host produce and transmit, and produce multi-direction launching beam launch via antenna.

64 transducers in antenna are divided into two groups, and one group is 3 transducers (as Fig. 4 a as shown in, totally 12 transducers) nearest apart from each summit of antenna, only carries out the reception of signal; 52 remaining transducers, composition octagon (as shown in Figure 4 b) can carry out the transmitting-receiving of signal.

What signal processing host produced transmits (electric signal) after power amplification, be sent to antenna, antenna transmits this to be converted to acoustic signals, and transducer in antenna is according to different assembled arrangement and phase differential, and the launching beam producing on different directions is launched.

Concrete: when acoustic emission, if phase value of each row's transducer is identical, 52 transducers are divided into 8 groups according to the size of phase value, are designated as sig1～sig8, when the phase place that sig1～sig8 transmits leading successively

time, form the wave beam tilting southward; The phase place transmitting as sig1～sig8 lags behind successively

time, form the wave beam tilting toward north.If the phase value of each row is identical, 52 transducers are divided into 8 groups according to the size of phase value, be designated as sig1 '～sig8 ', work as the phase place that sig1 '～sig8 ' transmits leading successively

time, form the wave beam tilting westerly; Working as the phase place that sig1 '～sig8 ' transmits lags behind successively

time, form the wave beam tilting toward east.

Further, this transmits as the form of multifrequency coding, for example, when a certain frequency continues after transmitting some time (, hundreds of millisecond), then launches with another frequency, continues transmitting with this.Concrete, as shown in Figure 5, the echo of L1 height layer, comprise frequency f 4 at the echo of moment t1, frequency f 3 at the echo of moment t2, frequency f 2 at the echo of moment t3, frequency f 1 echo data at moment t4.The echo of L2 height layer, comprise frequency f 5 at the echo of moment t1, frequency f 4 at the echo of moment t2, frequency f 3 at the echo of moment t3, frequency f 2 at the echo data of moment t4, frequency f 1 echo at moment t5.The echo of L3 height layer, comprise frequency f 6 at the echo of moment t1, frequency f 5 at the echo of moment t2, frequency f 4 at the echo of moment t3, frequency f 3 at the echo data of moment t4, frequency f 2 at the echo of moment t5, frequency f 1 echo data at moment t6.By that analogy.When carrying out after signal transmitting in the above described manner, can be in same aspect, receive that different frequency, in echoed signal in the same time not, has improved signal to noise ratio (S/N ratio).As shown in Figure 6, be the data of the corresponding a period of time length Δ t of an aspect Δ H.The initial time range transmission signal time of supposing reception signal is T0, and corresponding minimum reception altitude is H0.On H0 height, comprise the Initial Echo of f1 in the T0 moment; H1 height, comprise f1 at the T0+ Δ echo in t moment, f2 at the Initial Echo in the T0 moment, the echo data corresponding different frequency in sustained height layer is stacked up.H2 height, comprise f1 at the T0+2 Δ echo in t moment, f2 at the T0+ Δ echo in t moment, f3 is at the Initial Echo in T0 moment.H3 height, comprise f1 at the T0+3 Δ echo in t moment, f2 at the T0+2 Δ echo in t moment, f3 is at the T0+ Δ echo in t moment, f4 is at the Initial Echo in T0 moment.H4 height, comprise f1 at the T0+4 Δ echo in t moment, f2 at the T0+3 Δ echo in t moment, f3 is at the T0+2 Δ echo in t moment, f4 is at the T0+ Δ echo in t moment, f5 is at the Initial Echo in T0 moment.H5 height, comprise f1 at the T0+5 Δ echo in t moment, f2 at the T0+4 Δ echo in t moment, f3 is at the T0+3 Δ echo in t moment, f4 is at the T0+2 Δ echo in t moment, f5 is at the T0+ Δ echo in t moment, f6 is at the Initial Echo in T0 moment.By the accumulation of multiple-frequency signal, echoed signal is strengthened, and signal to noise ratio (S/N ratio) improves greatly.

Step 302, antenna reception backscattering echo and carry out pre-service after be sent to described signal processing host.

Sound wave is respectively to scattering in atmosphere, and antenna reception is converted to electric signal after backscattering echo (echoed signal), then carries out pre-service.

Pretreated process can as shown in Figure 7, be converted to echoed signal after electric signal, carries out signal and amplifies and process, recycling local oscillation signal I(sinx), Q(cosx) two-way carries out mixing and filtering and sampling to described backscattering echo respectively; Signal after sampling is divided into two-way: a route transmitting-receiving transducer by wave beam and mode synthesize signals and associated noises SigN, another route receiving transducer is according to the poor mode synthesized reference noise signal NoiseN of wave beam; Calculate respectively spectrum energy value Psig and the Pnoise of signals and associated noises and reference noise signal, obtain spectrum energy coefficient Coef1=Psig/Pnoise; The last noise signal (balanced noise) that deducts same homenergic from signals and associated noises, obtains denoised signal SigS=SigN-Coef1*NoiseN, and denoised signal is sent to signal processing host.

303, signal processing host, by composition algorithm, obtains wind speed trivector.

Need to first obtain the frequency shift amount f of each party to signal in each aspect _d(Doppler shift value), this value is the signal that the receives difference on the frequency during with this signal of transmitting.

Exemplary, for ensureing the accuracy of result of calculation, after can carrying out repeatedly adding up to data, calculate maximum value, concrete: first by the accumulative total of the different travel direction spectrum data of direction, as shown in Figure 8, the signal of described signal processing host after to denoising classified according to direction and distance, obtain different aspects in same direction data (generally according to direction classification, then to each party in data classify according to distance); Use fast Fourier transform fft algorithm to process respectively the data of different aspects in a direction, obtain corresponding signal spectrum; Again different frequency in this signal spectrum is added up in the spectrum data of same aspect and (in step 201, mentioned as strengthening echoed signal, improve signal to noise ratio (S/N ratio), in the time transmitting, continue after the transmitting some time with a certain frequency, launch with another frequency again), obtain spectrum result, using this result as the party to the directional spectrum data that obtain after last Echo Processing, when upwards processing after N time the party, obtain the directional spectrum data (for improving the accuracy of result, generally need accumulate repeatedly data result and carry out again subsequent calculations) after accumulation; Described N is greater than 1 natural number.

Again the wind speed of different directions in same aspect is merged to the trivector that obtains wind speed in this aspect, as shown in Figure 9, when all obtaining after the directional spectrum data after accumulation in each direction, respectively these directional spectrum data are carried out to smoothing processing and curve; Obtain each party to 2 maximum value in each aspect, in described 2 maximum value, have an interference value that is fixed echo, therefore need to remove; Remaining maximum value is the frequency shift amount f for transmitting in a certain aspect of a direction _d(Doppler shift value).

Frequency f during again according to transmitting ₀, frequency shift amount f _dwith velocity of propagation C calculate each party in each aspect to wind speed V _d: $V_d=\frac{C}{2}\frac{f_d}{f_0}.$

For the ease of understanding this wind speed computing formula, below introduce the derivation of this formula.

Suppose that transmitting acoustical signal frequency is f ₀, wavelength X, initial phase is φ ₀, C is the velocity of sound, and target range is L, and receiving signal is f with the difference on the frequency transmitting _d, echoed signal phase place is:

$\mathrm{\φ}={\mathrm{\φ}}_0-2\mathrm{\π}\frac{2L}{\mathrm{\λ}};$

Phase place over time rate is:

$\frac{\mathrm{d\φ}}{\mathrm{dt}}=-\frac{4\mathrm{\π}}{\mathrm{\λ}}\frac{\mathrm{dL}}{\mathrm{dt}};$

If the component motion of the relative beam axis direction of wind speed at distance L place is V _d, and regulation is towards the speed V of object of which movement _dfor on the occasion of, have $V_d=-\frac{\mathrm{dL}}{\mathrm{dt}};$

There is angular frequency simultaneously

so $2\mathrm{\π}\·f_d=\frac{4\mathrm{\π}}{\mathrm{\λ}}\·V_d\⇒f_d=\frac{2V_d}{\mathrm{\λ}};$ F _dit is Doppler shift value.

Again because, $\mathrm{\λ}=\frac{C}{f_0},$ So $f_d=\frac{2V_d}{\mathrm{\λ}}=\frac{2V_d\·f_0}{C}\⇒V_d=\frac{C}{2}\frac{f_d}{f_0}.$

After each party all being calculated to the wind speed in each aspect according to above-mentioned formula, can utilize vector composition algorithm (it is synthetic that for example, vector is carried out in the decomposition of least square method or trigonometric function) that the wind speed of different directions in a certain aspect is merged:

Suppose V _mnorth orientation wind speed, V _refor east orientation wind speed, V _rsfor south orientation wind speed, V _rwfor west is to wind speed, V _rzfor vertical direction wind speed, U, V, W represents that respectively wind vector is in east, north, the component in vertical direction, θ is beam tilt angle (this angle can be set in the time transmitting, and is generally 15 degree), has:

V _m=Vsinθ+Wcosθ

V _re=Usiθ+Wcosθ

V _rs＝-Vsiθ+Wcosθ

V _rw＝-Usiθ+Wcosθ

V _rz=W；

Can draw:

W=V _rz

U=（V _re-V _rw）/2sinθ

V=（V _rn-V _rs）/2sinθ

East and north component are upwards merged, obtain the big or small V of horizontal wind speed _hand offset angle:

$V_H=\sqrt{U^2+V^2},$

Work as V=0, U >=0 o'clock, α=90 °;

Work as V=0, when U < 0, α=270 °;

As V > 0, when U=0, α=0 °;

As V < 0, when U=0, α=180 °;

As V > 0, when U > 0, α=α ₀;

As V < 0, when U > 0, α=180 °-α ₀;

As V < 0, when U < 0, α=180 °+α ₀;

As V > 0, when U < 0, α=360 °-α ₀;

Wherein, ${\mathrm{\&alpha;}}_0={\tan }^{-1}\left|\frac{U}{V}\right|.$

Calculate according to said method after the trivector of every one deck windward speed, utilize data model, the true and false of data judged, if true, direct Output rusults; If false, be null result (for example, data being composed as-9999).

The Doppler shift that the embodiment of the present invention transmits relatively by the backscattering echo of sound wave in detection atmosphere comes calculation of wind speed and wind direction, the method can carry out the calculating of low latitude wind trivector fast and accurately, filled up home market and utilize the blank of acoustic detection low latitude wind.

The above; only for preferably embodiment of the present invention, but protection scope of the present invention is not limited to this, is anyly familiar with in technical scope that those skilled in the art disclose in the present invention; the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.

Claims (8)

1. the method that low latitude wind is surveyed, is characterized in that, the method comprises:

By the frequency f during respectively to the frequency of the backscattering echo of scattering and its transmitting on a certain aspect different directions receiving ₀compare, the signal that acquisition is launched towards a direction is at the frequency shift amount f of this aspect _d;

According to f ₀, f _dwith velocity of propagation C calculate each party in this aspect to wind speed V _d:

Utilize vector composition algorithm that the wind speed of different directions in this aspect is merged, obtain the trivector of wind speed in this aspect.

2. method according to claim 1, is characterized in that, the method also comprises:

Signal processing host produces and transmits and be sent to antenna, and antenna transmits this to be converted to acoustic signals, then by the transducer in antenna according to different assembled arrangement and phase differential, the launching beam producing on different directions is launched;

This acoustic signals respectively after scattering, is sent to described signal processing host by antenna reception backscattering echo and after carrying out pre-service in atmosphere, carries out the calculating of wind speed trivector by this signal processing host.

3. method according to claim 2, is characterized in that, the method also comprises:

Transducer in described antenna rearranges square according to 8 × 8 mode, and 3 transducers nearest apart from each summit in this square are receiving transducer, and all the other transducers are transmitting-receiving transducer;

In the time of antenna reception backscattering echo, by the synthetic signals and associated noises of transmitting-receiving transducer, receiving transducer synthesized reference noise signal; Taking described reference noise signal as benchmark, described signals and associated noises is carried out to denoising, and the denoised signal of acquisition is sent to described processing host.

4. method according to claim 3, is characterized in that, the method also comprises:

After described antenna reception backscattering echo, utilize local oscillation signal I, Q two-way respectively described backscattering echo to be carried out to mixing and filtering and sampling;

By transmitting-receiving transducer press wave beam and mode synthesize signals and associated noises SigN, receiving transducer is according to the poor mode synthesized reference noise signal NoiseN of wave beam;

Calculate respectively spectrum energy value Psig and the Pnoise of signals and associated noises and reference noise signal, obtain spectrum energy coefficient Coef1=Psig/Pnoise;

Obtain denoised signal SigS:SigS=SigN-Coef1*NoiseN according to formula.

5. method according to claim 3, is characterized in that, the method also comprises:

If each row transducer phase value identical, by transmitting-receiving transducer be divided into 8 groups according to the size of phase value, be designated as sig1～sig8, when the phase place that sig1～sig8 transmits leading successively

time, form the wave beam tilting southward; The phase place transmitting as sig1～sig8 lags behind successively

time, form the wave beam tilting toward north;

If the phase value of each row is identical, transmitting-receiving transducer is divided into 8 groups according to the size of phase value, be designated as sig1 '～sig8 ', work as the phase place that sig1 '～sig8 ' transmits leading successively

time, form the wave beam tilting westerly; Working as the phase place that sig1 '～sig8 ' transmits lags behind successively

time, form the wave beam tilting toward east.

6. method according to claim 2, is characterized in that, described in transmit as the form of multifrequency coding, when a certain frequency continues, after the transmitting some time, then to launch with another frequency.

7. method according to claim 1, is characterized in that, the method also comprises:

The signal of described signal processing host after to denoising classified according to direction and distance, obtains the data of different aspects in same direction; Use fast Fourier transform fft algorithm to process respectively the data of different aspects in a direction, obtain corresponding signal spectrum; Again different frequency in this signal spectrum is added up in the spectrum data of same aspect, obtain spectrum result, using this result as the party to the directional spectrum data that obtain after last Echo Processing, when upwards processing after N time the party, obtain the directional spectrum data after accumulation; Described N is greater than 1 natural number;

When all obtaining after the directional spectrum data after accumulation in each direction, respectively these directional spectrum data are carried out to smoothing processing and curve; Obtain each party to the maximum value in each aspect, using this maximum value as the frequency shift amount f transmitting in a certain aspect of a direction _d.

8. method according to claim 1, is characterized in that, the described vector composition algorithm that utilizes merges the wind speed of different directions in this aspect, and the step that obtains the trivector of wind speed in this aspect comprises:

According to the wind speed of a certain aspect different directions calculate wind vector in the Orient to wind speed component U and north wind speed component V upwards, and utilize vector composition algorithm that U and V are merged, the big or small V of acquisition horizontal wind speed _hand offset angle:

$V_H=\sqrt{U^2+V^2};$

Work as V=0, U >=0 o'clock, α=90 °; Work as V=0, when U < 0, α=270 °;

As V > 0, when U=0, α=0 °; As V < 0, when U=0, α=180 °;

As V > 0, when U > 0, α=α ₀; As V < 0, when U > 0, α=180 °-α ₀;

As V < 0, when U < 0, α=180 °+α ₀; As V > 0, when U < 0, α=360 °-α ₀;

Wherein, ${\mathrm{\&alpha;}}_0={\tan }^{-1}\left|\frac{U}{V}\right|.$

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