CN101576618A - Acoustic positioning measurement method based on wavelet transformation and measurement system thereof - Google Patents

Abstract

The invention relates to an acoustic positioning measurement method based on wavelet transformation and a measurement system thereof, which can conduct wavelet transformation to underwater target source signals collected, calculate the movement velocity of and distance from a target source and determine the location parameter of the target source according to a triangulation location method. The measurement method comprises the steps of: collecting a signal of the target source (S1); conducting wavelet transformation to the collected signal of the target source (S2), calculating velocity and distance (S3); estimating the location of the target source with the triangulation location method (S4); and outputting the location parameter (S5). The measurement system comprises a hydrophone array, a signal acquisition module, a signal processing module, a memory device and an output interface device.

Description

Hydrolocation measuring method and measuring system based on wavelet transformation

Technical field

The present invention relates to the hydrolocation measuring technique, particularly relate to the hydrolocation measuring method and the measuring system that adopt wavelet transformation.

Background technology

It all is very important that hydrolocation is measured for marine engineering design, marine environmental monitoring and scientific research of seas etc.

Hydrolocation measuring method commonly used at present comprises direction finding localization method, time delay localization method, Doppler frequency localization method etc., Doppler frequency localization method wherein is a kind of location technology of quick high accuracy, can Doppler frequency be measured by stationary signal time-frequency analysis principle such as Fourier transforms.

But Fourier transform is handled for the non-stationary signal in the actual measurement and is existed limitation.Along with the development of signal processing technology, wavelet transformation becomes a kind of new method that non-stationary signal is handled.

Summary of the invention

Development at signal processing technology, the present invention releases the new hydrolocation measuring method based on wavelet transformation, its purpose is by hydrophone array direct receiving target source signal from water, calculate the frequency variable of source signal according to the wavelet transformation of Doppler's principle, the movement velocity of inverting target source and distance, according to triangulation location, determine the location parameter of target source.Simultaneously, the present invention also releases the measuring system of implementing above-mentioned hydrolocation method based on wavelet transformation.

Measuring principle:

In the hydrolocation measuring process, the signal that directly receives from target source by nautical receiving set (receiver) battle array, can be because the signal projector of receiver or target source or the two relative motion simultaneously, and the different phenomenon of frequency that frequency that receiver receives and transmitter (target source) are sent, be Doppler effect, this principle is called Doppler's principle.

The ψ if transmitter transmits (t), the signal f (t) that receiver receives, v represents the speed of transmitter and receiver relative motion; Distance when establishing t=0 again between receiver and transmitter is R ₀, represent the distance between t receiver and transmitter at any time with R (t), have

R(t)＝R ₀+vt (1)

Work as v=0, this moment, transmitter was relative with receiver static, and the signal f (t) that receiver receives has

f(t)＝aψ(t-d) (2)

Wherein, a is the decay factor of wave source transmission amplitude loss, and d receives the time delay of phase of wave for transmitted wave, i.e. time delay,

d＝R _o/c (3)

Wherein, c representative emission velocity of wave propagation is the velocity of sound for underwater sound wave.

When v ≠ 0, this moment transmitter and receiver relative motion, the signal f (t) that receiver receives has

f(t)＝aψ(t-d(t)) (4)

Time delay d this moment (t) is the function of time,

$d\left(t\right)=\frac{R(t-d\left(t\right))}{c}=\frac{R_o+v(t-d\left(t\right))}{c}---\left(5\right)$

Derive

$d\left(t\right)=\frac{R_0+v\·t}{c+v}---\left(6\right)$

In wushu (6) substitution (4)

$f\left(t\right)=\mathrm{a\ψ}(t-\frac{v}{c+v}t-\frac{R_0}{c+v})---\left(7\right)$

$f\left(t\right)=\mathrm{a\ψ}(\frac{c}{c+v}t-\frac{R_0}{c+v})=\mathrm{a\ψ}\left(\frac{t-\frac{R_0}{c}}{\frac{c+v}{c}}\right)---\left(8\right)$

Order

$s=\frac{c+v}{c},$ Or $\frac{1}{s}=\frac{c}{c+v}---\left(9\right)$

$b=\frac{R_o}{c},---\left(10\right)$

Formula (8) is done variable replace, obtain

$f\left(t\right)=\mathrm{a\ψ}\left(\frac{t-b}{s}\right)---\left(11\right)$

When v＞0, f (t) is the stretching, extension of ψ (t); When v＜0, f (t) is the compression of ψ (t).

A is the factor that reflection receives ripple and transmitted wave relative intensity.In the ideal case, if f (t) equate with the energy of ψ (t), promptly || f|| ²=|| ψ || ², have

∫f ²(t)dt＝∫ψ ²(t)dt (12)

Then can try to achieve

$a=\sqrt{\frac{c}{c+v}}=s^{-\frac{1}{2}}=\frac{1}{\sqrt{s}}---\left(13\right)$

Substitution (12) obtains

$f\left(t\right)=\frac{1}{\sqrt{s}}\mathrm{\ψ}\left(\frac{t-b}{s}\right)---\left(14\right)$

S is a scale factor in the formula, and b is the time shift component, shows that f (t) is that the delay of ψ (t) and yardstick are flexible, just with wavelet transformation in basic small echo do translation and the form of stretching consistent.

The wavelet transformation of arbitrary function or signal x (t) is defined as:

${\mathrm{WT}}_x(a,\mathrm{\&tau;})=<x\left(t\right),{\mathrm{\&psi;}}_{a,\mathrm{\&tau;}}\left(t\right)>=\frac{1}{\sqrt{a}}\&Integral;x\left(t\right){\mathrm{\&psi;}}^{*}\left(\frac{t-\mathrm{\&tau;}}{a}\right)\mathrm{dt}---\left(15\right)$

ψ wherein ^*(t) be the conjugate complex number of ψ (t), ψ (t) is a wavelet mother function, ${\mathrm{\&psi;}}_{a,\mathrm{\&tau;}}\left(t\right)=\frac{1}{\sqrt{a}}\mathrm{\&psi;}\left(\frac{t-\mathrm{\&tau;}}{a}\right)$ Be called wavelet function, WT _x(a τ) is called wavelet coefficient.Wherein

Be normalized factor, a is called yardstick (or flexible) factor, and τ is called shift factor.Wavelet transformation has come down to introduce the thought of flexible and translation, promptly adopt a kind of position can be moved, shape can change " window ", have the T/F window of a flexibility and changeability, thereby satisfied the requirement of non-stationary signal being carried out the signal analysis of time-frequency localization.

Wavelet transformation WT _x(a τ) is exactly function x (t) ∈ L ²(R) at the ψ of respective function family _{A, τ}(t) decomposition on.The prerequisite that this decomposition is set up is that wavelet mother function ψ (t) should satisfy following admissibility condition (admissible condition), promptly

$C_{\mathrm{\&psi;}}=\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}\frac{{\left|\mathrm{\&Psi;}\left(\mathrm{\&omega;}\right)\right|}^2}{\left|\mathrm{\&omega;}\right|}\mathrm{d\&omega;}<\&infin;---\left(16\right)$

Ψ in the formula (ω) is the Fourier conversion of ψ (t).

With the wavelet transformation is that instrument is set up the wavelet analysis model of analyzing Doppler effect.Receive ripple by formula (14) this moment $f\left(t\right)=\frac{1}{\sqrt{s}}\mathrm{\&psi;}\left(\frac{t-b}{s}\right),$ ψ (t) is a transmitted wave.Therefore the logical waveform of band of limited duration always owing to transmit during real work directly makes wavelet transformation as basic small echo to ψ (t) with it, has

${\mathrm{WT}}_{\mathrm{\&psi;}}f(a,\mathrm{\&tau;})=\frac{1}{\sqrt{a}}\&Integral;\frac{1}{\sqrt{s}}\mathrm{\&psi;}\left(\frac{t-b}{s}\right){\mathrm{\&psi;}}^{*}\left(\frac{t-\mathrm{\&tau;}}{a}\right)\mathrm{dt}---\left(17\right)$

Make substitution of variable, order $t^{\&prime;}=\frac{t-b}{s},$ Be t=st '+b, dt=sdt ', substitution (17)

${\mathrm{WT}}_{\mathrm{\&psi;}}f(a,\mathrm{\&tau;})=\frac{1}{\sqrt{a/s}}\&Integral;\mathrm{\&psi;}\left(t^{\&prime;}\right){\mathrm{\&psi;}}^{*}\left(\frac{t^{\&prime;}-(\mathrm{\&tau;}-b)/s}{a/s}\right){\mathrm{dt}}^{\&prime;}---\left(18\right)$

${\mathrm{WT}}_{\mathrm{\&psi;}}f(a,\mathrm{\&tau;})={\mathrm{WT}}_{\mathrm{\&psi;}}\mathrm{\&psi;}(\frac{a}{s},\frac{\mathrm{\&tau;}-b}{s})---\left(19\right)$

As seen the wavelet transformation of received signal in fact reflecting transmit from wavelet transformation, promptly for basic small echo ψ (t) itself is made wavelet transformation with ψ (t).Except that differing from a translation b, also differing from an engineer's scale is scale factor s between the two.The former reflects the target location, and the latter causes that the ratio of wavelet transformation on diaxon is flexible.

According to the characteristic from wavelet transformation, WT _ψ(a, maximal value τ) always appears at a=1 to ψ, τ=0 place.So WT in the formula (19) _ψψ (a, τ) get the maximum value part must for:

$\frac{a}{s}=1,$ Be a=s;

$\frac{\mathrm{\&tau;}-b}{s}=0,$ Be τ=b

So, by WT _ψψ (a τ) gets the maximal value part and just can estimate s, the value of b, and further again through type (9) obtains the speed v of transmitter and receiver relative motion,

v＝(s-1)c (20)

Through type (10) obtains the distance R between receiver and transmitter ₀,

R _o＝cb (21)

Thereby obtain v, R _oEstimation.

When being distributed with n receiver under water,, obtain the speed v of target source and n receiver relative motion according to above-mentioned derivation _n, and the distance R that obtains target source and n receiver _n, according to triangulation location, the position of n receiver and target source space length joint is defined as the locus of target source.

Hydrolocation measuring method based on wavelet transformation involved in the present invention may further comprise the steps:

1, gather the signal of target source with hydrophone array, data transmission is to signal processing system.

2, the signal of gathering target source is carried out the wavelet transformation analysis of Doppler effect, obtain the speed of target source and receiver relative motion, and the distance that obtains target source and receiver.

3,,, estimate the location parameter of target source with the nautical receiving set more than 2 according to triangulation location.

Hydrolocation measuring system based on wavelet transformation involved in the present invention comprises hydrophone array, signal acquisition module, signal processing system, storer and output interface device.

Hydrophone array is a receiving hydrophone, is installed under water the receiving target source signal.

Signal acquisition module is a received signal sampled digital circuit, and the target source signal sampling that receives is digitized as signal data.

Signal processing system is a microprocessor, has the function of implementing above-mentioned hydrolocation measuring method based on wavelet transformation: the wavelet analysis that the signal data of gathering target source is carried out Doppler effect, obtain the speed of target source and receiver relative motion, and the distance that obtains order wave source and receiver.According to triangulation location, estimate the location parameter of target source.

Storer is preserved the computational data of target source signal data and signal processing system.

The output interface device has the data transfer mode of RS-232, USB standard, measurement result can be exported.

Description of drawings

Fig. 1 is the process flow diagram based on the hydrolocation measuring method of wavelet transformation that the present invention relates to.

Fig. 2 is the block diagram based on the hydrolocation measuring system of wavelet transformation that the present invention relates to.

Fig. 3 be the present invention relates to 2 nautical receiving sets, triangulation location estimates the synoptic diagram of target source position.

Embodiment

Now in conjunction with the accompanying drawings the present invention is done further detailed elaboration.

Fig. 1 shows the process flow diagram based on the hydrolocation measuring method of wavelet transformation that the present invention relates to.As shown in Figure 1, the hydrolocation measuring method based on wavelet transformation may further comprise the steps:

S1-gathers the signal of target source

S2-carries out wavelet transformation to the signal of gathering target source

S3-computing velocity and distance

The position of S4-triangulation location estimation target source

S5-outgoing position parameter

Fig. 2 is the block diagram based on the hydrolocation measuring system of wavelet transformation that the present invention relates to.As shown in Figure 2, the ingredient based on the hydrolocation measuring system of wavelet transformation comprises hydrophone array, signal acquisition module, signal processing system, storer and output interface device.

Fig. 3 be the present invention relates to 2 nautical receiving sets, triangulation location estimates the synoptic diagram of target source position.As shown in Figure 3, in that (x is y) in the coordinate plane, towards 2 nautical receiving set h on y axle right side ₁, h ₂, the signal of collection target source S; Carry out wavelet transformation computing velocity and distance, calculate and obtain h ₁, h ₂Be respectively R with the distance of S ₁, R ₂By triangulation location, with h ₁Be center, R ₁For the circle of radius and with h ₂Be center, R ₂For the intersection point of circle on y axle right side of radius is the position of S.

Claims (6)

1, a kind of hydrolocation measuring method based on wavelet transformation, it is characterized in that comprising: the signal (S1) of gathering target source, the signal of gathering target source is carried out wavelet transformation (S2), computing velocity and distance (S3), the position (S4) of triangulation location estimation target source, the location parameter in export target source (S5).

2, the hydrolocation measuring method based on wavelet transformation according to claim 1 is characterized in that, the signal (S1) of gathering target source is the signal with hydrophone array receiving target source, then by signal acquisition module with data transmission to signal processing system.

3, the hydrolocation measuring method based on wavelet transformation according to claim 1 is characterized in that, the signal of gathering target source is carried out the wavelet transformation analysis (S2) of Doppler effect.

4, the hydrolocation measuring method based on wavelet transformation according to claim 1 is characterized in that, calculates the speed of target source and receiver relative motion, and the distance (S3) that obtains target source and receiver.

5, the hydrolocation measuring method based on wavelet transformation according to claim 1 is characterized in that, according to triangulation location, with the nautical receiving set more than 2, estimates the location parameter (S4) of target source.

6, a kind of hydrolocation measuring system of implementing the hydrolocation measuring method based on wavelet transformation according to claim 1 is characterized in that, comprises hydrophone array, signal acquisition module, signal processing system, storer and output interface device; Hydrophone array is a receiving hydrophone, is installed under water the receiving target source signal; Signal acquisition module is a received signal sampled digital circuit, and the target source signal sampling that receives is digitized as signal data; Signal processing system is a microprocessor, have implement above-mentioned based on the signal data analysis of wavelet transformation and the function of hydrolocation measuring method: storer is preserved the computational data of target source signal data and signal processing system; The output interface device has the data transfer mode of RS-232, USB standard, measurement result can be exported.

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