CN202330736U - Electric-method exploration device - Google Patents

Abstract

The utility model relates to an electric-method exploration device, which transmits signals by a transmitter and processes the received signals by a receiver, wherein the transmitter comprises a global positioning system (GPS) module (1), a paseudorandom signal generator (2), a driving and protecting module (3), an intelligent power module (IPM) (5), a temperature control module (4), a power supply module (7) and transmitting electrodes AB (6); and the receiver comprises a GPS module (8), a paseudorandom signal generator (9), receiving electrodes MN (10), a preamplification module (11), a filter and trap module (12), a precise amplification module (13), an autocorrelator (14), a cross correlator (15), a first FFT (fast Fourier transform) converter (16), a second FFT (fast Fourier transform) converter (17), a frequency response generator (18), a complex-resistivity spectrum generator (19), a fitter (20) and an inverter (21).

Description

A kind of resistivity prospecting device

Technical field

The utility model relates to the resistivity prospecting field, in particular to a kind of resistivity prospecting device and system.

Background technology

The application of resistivity prospecting (particularly induced polarization method) is very extensive seeking aspect the mineral metal products, but because production mine and near a large amount of high voltage transmission line and the various electricity consumption facilities of existence thereof, this will produce extremely strong electromagnetic interference signal; A large amount of metallic conduit, stock rail and barren rock slags causes very big difficulty all for the power supply of electrical method and electric field reception in the underground mining tunnel.All these have all influenced the effect of resistivity prospecting method, so there is the severe noise interference problem in resistivity prospecting when solving crisis mine problem.

Although electromagnetic interference (EMI) is very big near the production mine; But generally be the interference of randomness; And the Correlation Identification technology is a kind of system identifying method that can remove random noise disturbance effectively; All obtained using widely in fields such as machinery, robotization, instrument and meter, cognitive science, bioinformatics, but aspect geophysical exploration, but do not obtained enough attention and application.

At present, in the resistivity prospecting generally be through pile up, methods such as filtering, reference far away remove noise, but these methods are used to remove noise and just seem powerless in the resistivity prospecting of mine, so reconnoitre weak effect, directly bring manpower financial capacity's huge waste.And in order to improve signal to noise ratio (S/N ratio), a method commonly used is exactly to improve the power that sends power supply, and this must cause transmitter heavy unusually, and this brings huge difficulty for the investigation and prospecting in mountain area.

On the other hand, induced polarization method is the most effectively means, particularly complex resistivity method that are used to look for the ore deposit in the resistivity prospecting, and more electrical parameter can be provided, and detection accuracy is higher.Complex resistivity method is meant through measuring a kind of resistivity prospecting method of complex resistivity spectrum frequency response just; But the electric field response that needs to measure a plurality of frequencies just can obtain a frequency response curve; And need low frequency the time chronic; Therefore detection efficiency is very low, though this is to cause the good reason that can not find broad application of complex resistivity method effect.

If in resistivity prospecting, adopt the Correlation Identification technology; One-shot measurement just can obtain a frequency response curve so; Can effectively solve the inefficiency problem of complex resistivity method; And have the high advantage of complex resistivity method detection accuracy, so this is the complex resistivity method that a kind of new time domain is measured.

Fig. 1 (a) and (b) show the observation device and the equivalent electrical circuit of complex resistivity method in the prior art.

Traditional complex resistivity method is amplitude spectrum and phase spectrum or the real component and the imaginary component spectrum of looking complex resistivity through observation on quite wide ultralow frequency range, with research underground medium situation.Like Fig. 1 (a) with (b); Send the each sinusoidal wave or square wave that sends a frequency of current source AB; Receive terminal MN and record corresponding voltage signal, repeatedly measure the amplitude and the phase propetry of a plurality of frequencies in the frequency range, obtain complex resistivity spectrum; Utilize Cole-Cole's model to carry out match and inverting again, obtain electrical parameters such as dc resistivity, charge rate, time constant and frequency correlation coefficient and carry out GEOPHYSICAL EXPLANATION.

This method can provide the sharp electrical information of rich, could obtain than the whole spectrum but need on many frequencies, to do observation, so production efficiency is low.

The utility model content

The purpose of the utility model is to utilize the Correlation Identification technology to remove random noise; Thereby once just can obtain a frequency response curve in the time domain measurement and improve detection efficiency; In addition, make an explanation through adopting two Coles-Cole's model, not only can remove the influence of electromagnetic coupling effect, can also obtain electromagnetic parameter, detection accuracy improves.

An aspect according to the utility model; A kind of transmitter that is used for resistivity prospecting is provided; It is characterized in that said transmitter comprises global position system GPS (Global Positioning System) module (1), pseudo random signal generator (2), driving and protection module (3), SPM IPM (Intelligent Power Modules) (5), temperature control modules (4) and supply module (7) and sender electrode AB (6); Wherein, GPS module (1) is transmitted the time service synchronizing information through serial ports to pseudo random signal generator (2), accomplishes the storage of data message, and controlling and driving and protection module (3); Drive and protection module (3) driving IPM (5) work, holding circuit is used to protect the safety of total system; Temperature control system (4) monitoring transmitter temperature inside, machine or closing machine reset after surpassing predetermined value; IPM (5) will export conversion of signals and become to be used for the current signal of resistivity prospecting and carry electric current to sender electrode AB (6); Supply module (7) is for integrated circuit board provides low-tension supply, and for IPM (5) required high pressure is provided.

Preferably, pseudo random signal generator (2) is further exported the m sequence or the contrary Repeated m-Sequences of different rank, different frequency as required, and collocating LCD is used to show transmitter signal type, parameter and state.

According to the utility model on the other hand; A kind of receiver that is used for resistivity prospecting is provided, it is characterized in that said receiver comprises GPS module (8), pseudo random signal generator (9), receiving electrode MN (10), pre-amplifying module (11), filtering and trap module (12), accurate amplification module (13), autocorrelator (14), cross-correlator (15), a FFT transducer (16), the 2nd FFT transducer (17), frequency response maker (18), complex resistivity spectrum maker (19), match device (20) and inverter (21).

Wherein, GPS module (8) is transmitted the time service synchronizing information through serial ports to pseudo random signal generator (9); Realize precisely synchronously and keep accurate homophase that pseudo random signal generator (9) is exported the m sequence of identical exponent number with transmitter, same frequency as required with the pseudo-random sequence of transmitter; Receiving electrode MN (10) receives the potential difference (PD) that transmits through underground medium; Pass through pre-amplifying module (11) then the electromagnetic signal that receives is carried out preliminary amplification; And, through accurate amplification module (13) signal of filtering noise is carried out the accurate amplification of low noise again through the industrial frequency noise of filtering and trap module (12) filter away high frequency noise and system; Autocorrelator (14) is realized the auto-correlation computation of pseudo random signal; Cross-correlator (15) is realized pseudo random signal and the computing cross-correlation that receives signal.

The one FFT transducer (16), the 2nd FFT transducer (17) carry out time-frequency conversion to auto-correlation result and cross correlation results respectively; Frequency response maker (18) computing obtains removing the earth system frequency response after recording geometry influences; The earth system frequency response obtains the complex resistivity spectrum of the earth system through complex resistivity spectrum maker (19); Match device (20) obtains the sight-reading parameter according to two Coles-Cole's model fitting, and inverter (21) carries out joint inversion and obtains true spectrum parameter; Thereby obtain geophysical parameters information, and carry out real time data graphic presentation and storage.

According to the utility model more on the one hand, a kind of resistivity prospecting system is provided, it is characterized in that comprising above-mentioned transmitter and receiver.

Compared with prior art, can bring following technique effect according to the technical scheme of the utility model:

1, can remove the random disturbance that superposes in the reception signal.According to Wei Na-Hough equation, with the pseudo random signal of input the output signal is carried out computing cross-correlation, because the random noise that superposes in input signal and the output signal is uncorrelated, so random noise is eliminated.

2, can remove the influence of recording geometry to measurement result.For a real system, electrode, lead, impedance ground and measurement mechanism all can exert an influence to measurement result and reduce the accuracy of identification, utilize de-convolution operation, and this influence is easy to be removed.Said de-convolution operation can realize at frequency domain.

3, can access the true spectrum parameter and the geometric distributions of target polarization body.What impulse response that single input list output identification obtains and frequency response reflected is the group effect that sends the interior underground medium of exploration volume between the receiving electrode; Adopt the high density geometric sounding method of multipole distance; Can access the true spectrum parameter and the geometric distributions of target polarization body; Have advantages such as level and along track resolution are high, the unusual amplitude of reflection is big, particularly the geologic prospect effect is better under MODEL OVER COMPLEX TOPOGRAPHY.

4, can remove the influence of electromagnetic coupling effect.The influence of how to remove electromagnetic coupling effect in the induced polarization method all is people's problem demanding prompt solution all the time.Utilize the two Coles-complex resistivity method of Cole's model not only can obtain swashing 4 parameters of electrical effect; Can also obtain 3 parameters about electromagnetic coupling effect; Therefore not only can separate galvanomagnetic effect to swashing the influence of electrical quantity; Utilize electromagnetic parameter can also obtain more information, so detection accuracy improve greatly.

Description of drawings

Fig. 1 (a) shows the observation device of complex resistivity method;

Fig. 1 (b) shows the equivalent electrical circuit of complex resistivity method;

Fig. 2 shows the identification model according to the resistivity prospecting method of the utility model;

Fig. 3 shows the impulse response (is example with a typical second-order system) of treating identification system;

Fig. 4 (a) shows the m sequence of one-period;

Fig. 4 (b) shows the contrary Repeated m-Sequences of one-period;

Fig. 4 (c) shows the synoptic diagram of white Gaussian noise;

Fig. 5 shows the impulse response and true impulse response contrast synoptic diagram that utilizes the identification of m sequence to obtain;

Fig. 6 shows the impulse response and true impulse response contrast synoptic diagram that utilizes contrary Repeated m-Sequences identification to obtain;

Fig. 7 shows according to the situation of considering the influence of recording geometry in the identification model of the resistivity prospecting method of the utility model;

Fig. 8 shows the contrast synoptic diagram of treating identification system impulse response deconvolution front and back;

Fig. 9 shows multipole synoptic diagram apart from recording geometry;

Figure 10 shows the contrast synoptic diagram before and after two Coles-Cole's model amplitude spectrum identification;

Figure 11 shows the contrast synoptic diagram before and after two Coles-Cole's model phase spectrum identification;

Figure 12 shows the amplitude/phase synoptic diagram of two Coles-Cole's model fitting;

Figure 13 shows the real part/imaginary part synoptic diagram of two Coles-Cole's model fitting;

Figure 14 shows the synoptic diagram according to transmitter in the resistivity prospecting device of the utility model;

Figure 15 shows the synoptic diagram according to receiver in the resistivity prospecting device of the utility model.

Embodiment

Fig. 2 shows the identification model according to the resistivity prospecting method of the utility model.Its ultimate principle is Wei Na-Hough equation.Its core is to adopt pseudo-random sequence (comprising m sequence and contrary Repeated m-Sequences) that the time series that receives is carried out relevant treatment, obtains impulse response, and changing to frequency domain to impulse response is exactly frequency response.

System is input as v (t); The signal that output u (t) just measures; H (t) is an impulse response of treating identification system, and r (t) is the response behind input v (t) the process system under test (SUT), outside random noise disturbance n (t); It is known wherein importing v (t), exporting u (t), and it is immesurable, unknown disturbing n (t).

The input/output signal v of system (t), u (t) have following relation:

u(t)＝r(t)+n(t)＝v(t)*h(t)+n(t) (1)

H in the formula (t) is the time domain impulse response of system under test (SUT), and * is a convolution algorithm.

Formula (1) both sides use input signal v (t) to carry out computing cross-correlation simultaneously:

R _vu(t)＝R _vv(t)*h(t)+R _vn(t) (2)

R in the formula _Vu(t) simple crosscorrelation of expression input and output, R _Vv(t) auto-correlation of expression input, R _Vn(t) simple crosscorrelation of n (t) and input signal is disturbed in expression.

Because outside random noise disturbance and input signal are uncorrelated, therefore the R in (2) formula _Vn(t) be 0.Can see the interference of random noise that the result of computing cross-correlation has been cancellation.Therefore obtain

R _vu(t)＝R _vv(t)*h(t) (3)

Here it is famous Wei Na-Hough equation.Therefore, as long as we obtain the autocorrelation function R of input _Vv(t) and the simple crosscorrelation R of input and output _Vu(t), just can obtain the time domain impulse response h (t) of system under test (SUT) through the method for deconvolution.Transforming to frequency domain is exactly frequency response.So once send and receive and just obtained a frequency response curve, comprise amplitude-frequency response and phase-frequency response, improved detection efficiency greatly.

If but input is general signal, solving equation (3) is the comparison difficulty so.For this reason we to seek some special signals as input signal to simplify solution procedure.And the autocorrelation function of white noise signal has special form, and its autocorrelation function is a δ function.When by identification system be input as white noise the time, as long as obtain the cross correlation function between the input/output signal, just can be divided by directly obtains the impulse response of system.But white noise be mathematical one abstract, be not easy to realize more do not have repeatability on the engineering.The normal pseudo random signal of using is as input signal in the engineering.It has the character of approximate white noise, thus can guarantee good identification precision, and on engineering, realize easily.

The pseudo random signal that identification is adopted usually is m sequence or contrary Repeated m-Sequences.The m sequence is meant maximum-length shift register sequence.Contrary Repeated m-Sequences is also claimed the L sequence, is to one times of m sequence extension, after the negate of position, produces then, because average is 0 in one-period, therefore when carrying out system's Correlation Identification, has than m sequence excellent characteristic more.Accompanying drawing 3 is impulse response h (t) that treat identification system, is example with a typical second-order system.Accompanying drawing 4 (a) is an one-period, and length is 31 m sequence, and Fig. 4 (b) is the contrary Repeated m-Sequences of one-period, and Fig. 4 (c) is noise superimposed n (t).Accompanying drawing 5 is to utilize the m sequence to carry out the result of Correlation Identification, can see, the real impulse response of impulse response fundamental sum that recovers through Correlation Identification overlaps, and it is very little that The noise becomes.Accompanying drawing 6 is to utilize contrary Repeated m-Sequences to carry out the result of Correlation Identification, and identification effect is better than m sequence.

In addition, in a preferred embodiment of the utility model, in order to remove the influence of electrode, lead, impedance ground and measurement mechanism, in the data handling procedure of receiver, carried out de-convolution operation, its principle is following:

The influence of electrode, lead, impedance ground and measurement mechanism is summed up as a system, and its impulse response is h _s(t), the impulse response of the earth system is designated as h _e(t), shown in accompanying drawing 7.(1) formula becomes so

u(t)＝v(t)*h _e(t)*h _s(t)+n(t) (4)

(4) computing cross-correlation is carried out with the input pseudo-random sequence in the formula both sides, and influence that just can the cancellation random noise obtains

R _vu(t)＝R _vv(t)*h _e(t)*h _s(t) (5)

Therefore, ask the simple crosscorrelation r of input and output signal earlier _Vu(t) and the auto-correlation R of input signal _Vv(t), obtain the total impulse response h of recording geometry and the earth system after the de-convolution operation _e(t) * h _s(t), and then through de-convolution operation remove recording geometry h _s(t) influence obtains the impulse response h of the earth system _e(t).Can find out that from accompanying drawing 8 impulse response after the influence of removal recording geometry is more near the impulse response of treating identification system.

Also can change into the computing of multiplying each other or being divided by to convolution and de-convolution operation at frequency domain or complex frequency domain.Therefore (5) formula becomes:

P _vu(ω)＝P _vv(ω)·H _e(ω)·H _s(ω) (6)

So just obtain treating the frequency response of identification system:

$H_e\left(\mathrm{\ω}\right)=\frac{P_{\mathrm{vu}}\left(\mathrm{\ω}\right)}{P_{\mathrm{vv}}\left(\mathrm{\ω}\right)\·H_s\left(\mathrm{\ω}\right)}---\left(7\right)$

Near the result that Correlation Identification obtains transmitter just thinks the impulse response h of recording geometry _s(t),, can ignore the influence of the earth system, think the influence of having only recording geometry because near transmitter.Change to frequency domain to it and be H _s(ω).

That in geophysics, use is complex resistivity spectrum ρ (ω).It with the relation of frequency response is:

ρ(ω)＝K·H _e(ω) (8)

Here K is called electrode coefficient.Shown in Fig. 1 (a), A, B are a pair of sender electrodes, and M, N are a pair of receiving electrodes, and the size of electrode coefficient depends on the relative position of A, M, N, B four electrodes so:

$K=\frac{2\mathrm{\π}}{\frac{1}{\mathrm{AM}}-\frac{1}{\mathrm{AN}}+\frac{1}{\mathrm{BN}}-\frac{1}{\mathrm{BM}}}---\left(9\right)$

AM, AN, BN, BM are interelectrode distance in the formula.

Obtain after the complex resistivity spectrum, utilize complex resistivity method to carry out GEOPHYSICAL EXPLANATION.Usually complex resistivity method adopts branch that-Cole model to carry out match:

$\mathrm{\ρ}\left(\mathrm{\ω}\right)={\mathrm{\ρ}}_0\{1-m[1-\frac{1}{1+{\left(\mathrm{j\ω\τ}\right)}^c}\left]\right\}---\left(10\right)$

Match obtains 4 sharp electrical quantity ρ like this ₀, m, τ, c.Owing to contain the influence of electromagnetic coupling effect in the complex resistivity spectrum, so the sharp electrical quantity that obtains like this is not accurate enough.

And utilize two Coles-Cole's model (shown in the formula (11)) to carry out match and not only can obtain 4 sharp electrical quantity ρ ₀, m ₁, c ₁, τ ₁, can also obtain 3 parameter m about electromagnetic coupling effect ₂, c ₂, τ ₂

$\mathrm{\ρ}\left(\mathrm{\ω}\right)={\mathrm{\ρ}}_0\{1-m_1[1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_1\right)}^{c_1}}\left]\right\}\{1-m_2[1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_2\right)}^{c_2}}\left]\right\}---\left(11\right)$

What these 7 parameters reflected is the overall information in the electrode spread exploration volume, is called the sight-reading parameter, and their physical significance is:

1. ρ ₀-expression zero-frequency apparent resistivity: the average resistivity in the reflection electrode spread exploration volume.

2. m ₁-swash the apparent chargeability of electrical effect: swash electrical effect intensive parameter (%), with the polarizable material volume content positive correlation in the electrode spread exploration volume.

3. τ ₁-swash constant between the apparent time of electrical effect: swash electrical effect characteristic parameter (second), relevant with the structural informations such as granule size of polarizable material in electrode spread is explored volume.

4. c ₁-swash the video frequency related coefficient of electrical effect: swash electrical effect procedure parameter (dimensionless), relevant with the sharp electrical effect type and the polariton substance mixed distribution homogeneity of polarizable material in the electrode spread exploration volume.

5. m ₂The apparent chargeability of-galvanomagnetic effect.

6. τ ₂Constant between the apparent time of-galvanomagnetic effect.

7. c ₂The video frequency related coefficient of-galvanomagnetic effect.

Therefore this method not only can be separated sharp electricity spectrum and EM coupling spectrum, utilizes the electromagnetic parameter that obtains can also obtain residual electricity magnetic effect (REM) parameter

With electromagnetism apparent resistivity ρ _ωDeng, therefore can improve detection accuracy.

What obtain at a measuring point is the sight-reading parameter; What we needed is true Cole-Cole's parameter of target polarization body (ore body that just need verify or hydrocarbon-bearing pool etc.) and its geometric distributions (comprising information such as the degree of depth, thickness, occurrence), so need the information of the measuring point more than 2.Take multipole distance observation, quantity of information is just greatly abundant.Therefore in a preferred embodiment of the utility model, adopted the method for geometric sounding---multipole apart from observation, can obtain the information of the anomalous body of different depth.

This working method is as shown in Figure 9, and AB is a sender electrode, M ₁N ₁Be first pair of receiving electrode, N ₁M ₃(be M ₂N ₂) be second pair of receiving electrode, M ₃N ₃Be the 3rd pair of receiving electrode.A plurality of receivers of collinear arrangement receive the electric field response that sends electric dipole source simultaneously, and transmitting-receiving is apart from increasing by certain spacing.Because different transmitting-receivings is different apart from the degree of depth of surveying, transmitting-receiving is big more apart from the degree of depth of big more reflection, therefore once supplies power at a supply terminals, just can receive the electric field response of a plurality of frequencies of different depth.Press repeatedly mobile observation system of certain some distance along section, just can observe the radial electric fields response of a plurality of frequencies of different transmitting-receiving distances on the section, obtain abundant electric field information.Can take following two kinds of methods by multipole true spectrum parameter and the geometric distributions that obtains the target polarization body apart from observed result.

1. to the measurement result of multipole distance just the sight-reading of a plurality of measuring points carry out joint inversion, can obtain the geometric distributions and the true spectrum parameter of target polarization body.Earlier the complex resistivity spectrum (comprising amplitude and phase place) of each measuring point is isolated the sight-reading of polarization body and country rock with conventional complex resistivity method inverting, again to the true spectrum parameter and the geometric distributions that the phase spectrum joint inversion obtains the target polarization body of looking of isolated a plurality of different poles distances.

2. utilize the parameter of isolated galvanomagnetic effect can calculate residual electricity magnetic effect (REM) parameter and 2 electromagnetic parameters of electromagnetism apparent resistivity, they can descend electric conductivity unusual than conventional apparent resistivity more delicately corresponsively.The complex resistivity spectrum of each measuring point of inverting can obtain six parameters like this: four sharp electrical quantitys, two electromagnetic parameters.Multipolely represent with the pseudosection map of six parameters, can reflect that ground electricity structure is along section with the variation of the degree of depth apart from observed result.

It will be understood by those of skill in the art that in Fig. 1, Fig. 9, transmitting terminal is not necessarily used electric dipole source, also can use any one resistivity prospecting such as magnetic source coil to use active source.Receiving end also not necessarily receives with dipole, can use any resistivity prospecting such as bar magnet to use receiver.In addition, send receiving and not necessarily to adopt as Fig. 9 multipole apart from observation device, can be this collinear arrangement, also can be axial measurement, can be this one and send out receipts a plurality of, also can one receipts, perhaps a MIMO.In addition, to the frequency response that obtains,, can also explain with dc resistivity, induced polarization method, electromagnetic method except explaining with complex resistivity method.Near 0 o'clock, frequency response curve was exactly the direct current apparent resistivity of this measuring point in the value of this point in frequency, obtained can using the dc resistivity inverting after the value of a plurality of measuring points.At high frequency (for example greater than 10 ⁴Hz), can ask for some electromagnetic parameters, adopt the Data Processing and the inversion method of electromagnetic method.Then can obtain some sharp electrical quantitys in low-frequency range, for example the parameters such as rate of change of low frequency complex resistivity between rate of change, road between apparent rate of frequency spread, apparent rate of frequency spread road.In addition, also can be directly the impulse response of time domain be carried out GEOPHYSICAL EXPLANATION.When considering complex resistivity method, also be not necessarily two Coles-Cole's model of this product form, also can be the two Coles-Cole's model with form, can also be perhaps other models of Dias model, Brown model.

Compared with prior art, the difference according to the technical scheme of the utility model is at least:

1, adopts pseudo-random sequence (comprising m sequence and contrary Repeated m-Sequences) that the time series that the electrical method receiver receives is carried out computing cross-correlation, obtain the impulse response and the frequency response of system;

2, adopt deconvolution to remove the influence of recording geometry;

3, the observed pattern of the multipole distance of employing obtains the true spectrum parameter and the geometric distributions of target polarization body;

4, adopt complex resistivity method to carry out inversion interpretation to the frequency response that obtains.Adopt two Coles-Cole's model can obtain electromagnetic parameter, survey meticulousr.For the technique effect to the utility model technical scheme has a better understanding, below describe through a simulation example.

Because the characteristic of typical second-order system is that we know, identification effect is comparison easily also, thus following be example with identification result to a second-order system.Suppose that one is treated that identification second-order system impulse response is h (t)=ae ^BtSin (ct) gets a=11.547, b=-5, and c=8.66, as shown in Figure 3.This second-order system cutoff frequency is 2Hz, and its impulse response goes to zero behind 1s basically, so be about 1s the transit time of system.Select formula (12) and (13) according to parameter, the chip width of pseudo-random sequence can be selected 0.02s, and the Cycle Length of sequence is 63 to get final product.

$0.443\frac{1}{\mathrm{\Δ}}\≥f_{\max }---\left(12\right)$

$N=(1.2-1.5)\frac{T_s}{\mathrm{\Δ}}---\left(13\right)$

Here Δ is the chip width, f _MaxBe system's cutoff frequency, T _sBe the transit time of system, N is the Cycle Length of sequence.In order to obtain better identification effect, code fetch sheet width is 0.01s, and sequence length is got 100 points.The pseudo-random sequence that in the actual identification process, can send several cycles (for example 3-5 cycle) is to obtain better identification effect.Receiver also can select effect preferably waveform carry out computing.

In process to the underground medium System Discrimination of reality, for take into account the high and low frequency resolution and with the contradiction of shift register number, can be divided into several frequency ranges and carry out.In addition, SF can be improved, in a chip width, a plurality of points can be gathered in order to improve identification precision.

White Gaussian noise is the common noise type, and Fig. 4 (c) is that SF is 1kHz, the white Gaussian noise of 10000 sampled points, and the standard deviation of noise is 1.Fig. 4 (a) is the pseudorandom m sequence current signal that sender electrode sends, and Fig. 4 (b) is the contrary Repeated m-Sequences current signal of pseudorandom that sender electrode sends, and Fig. 5 and Fig. 6 are respectively the results with m sequence and contrary Repeated m-Sequences Correlation Identification.Can see that through after the Correlation Identification, random noise is very little to the impulse response influence that identification obtains, and, adopt contrary Repeated m-Sequences identification effect better.

Consider to remove the influence of recording geometry.Fig. 8 is the actual impulse response of treating the typical second-order system of identification, the contrast of the impulse response before and after the deconvolution; Can see; Utilize deconvolution to remove the later result's (solid line of white) of the influence of recording geometry more near the impulse response of real system (red+word line); Both overlap basically, and the result's (green diamond curve) who does not pass through deconvolution then differs bigger with real system.

The impulse response that obtains like this changes to frequency domain through Fourier transform, is exactly H _e(ω).(8) formula of utilization obtains complex resistivity spectrum ρ (ω).

For two Cole-Cole's model system (is example with the product form), suppose that the parameter of setting is respectively ρ ₀=25, m ₁=0.1, c ₁=0.12, τ ₁=1, m ₂=0.67, c ₂=0.95, τ ₂=0.01, having added standard deviation is the white Gaussian noise of 1V, and Correlation Identification complex resistivity spectrum ρ (ω) as a result can be expressed as amplitude spectrum (see figure 10) and phase spectrum (seeing Figure 11).Result after the identification (white+word line) has only got the positive frequency part.Can see that identification effect is better, fundamental sum real system spectrum overlaps.

Adopt classical inverting approximating method damped least square method that the complex resistivity spectrum that obtains is carried out match, can obtain ρ ₀, m ₁, c ₁, τ ₁, m ₂, c ₂, τ ₂Totally 7 sharp electricity and electromagnetic parameter are referring to formula (11).

Choosing of initial value is very crucial when adopting damped least square method to carry out match, and the initial value selection is improper may to cause not convergent situation, thereby can not get the result of needs.Two Coles-Cole's model is carried out match have 7 undetermined parameters, the many matches of parameter are more difficult to obtain desirable effect, so selects suitable initial value just to seem crucial more.Here specify the system of selection of initial value.

At first, this Several Parameters has span: c ₁Span between 0.1-0.6, c ₂Span be 0.9-1.0, m ₁, m ₂Span between 0-0.98, and m ₁＜m ₂, τ ₁＞＞τ ₂And the value ρ of zero-frequency resistivity ₀It is exactly the value of the low-frequency asymptote of amplitude or real part.

τ ₂Also be easy to obtain.When the high band EM coupling had comparative advantage, imaginary component had individual peak value, and this crest frequency is with regard to the timeconstant of corresponding electromagnetic coupling effect ₂Again according to τ ₁＞＞τ ₂Can estimate τ ₁

m ₁, c ₁And m ₂, c ₂Variation range all little, therefore it is just passable in their span, to get an estimated value, such as m ₁=0.25, c ₁=0.25, m ₂=0.75, c ₂=1.

In addition, to cause last iteration result in order preventing in the iterative process too greatly not in the effective range of parameter because revise step-length, even negative value to occur, in program, can preestablish ρ ₀, m ₁, c ₁, τ ₁, m ₂, c ₂, τ ₂Seven parameter range not only can have been accelerated the speed of iterative fitting but also can guarantee the accuracy of match.

Figure 12 and 13 is that two Cole-(parameter setting is ρ to Cole's model to one ₀=25, m ₁=0.1, c ₁=0.12, τ ₁=0.1, m ₂=0.67, c ₂=0.95, τ ₂=0.003) fitting result, iteration have just reached the error threshold requirement of setting for 8 times.Facts have proved that this method is effective.

Said process is the situation that a measuring point is obtained the sight-reading parameter of this measuring point.In order to obtain the true spectrum parameter and the geometric distributions of target polarization body, need carry out multipoint observation.Multipole is a kind of highdensity geometric sounding mode apart from observed pattern, and this working method is as shown in Figure 9, once supplies power at a supply terminals, just can receive the electric field response of the different frequency of different depth.AB is a sender electrode, M ₁N ₁Be first pair of receiving electrode, N ₁M ₃(be M ₂N ₂) be second pair of receiving electrode, M ₃N ₃Be the 3rd pair of receiving electrode.Utilize (8) formula obtain different measuring points just different poles apart under complex resistivity spectrum; Utilize damped least square method inverting match to obtain 7 sight-reading parameters again; And then utilize joint inversion method really to be composed parameter and geometric distributions; Or obtaining 6 pseudosection maps that swash electricity, electromagnetic parameter by these 7 sight-reading parameters, expression ground electricity structure is along section with the variation of the degree of depth.

Figure 14 and Figure 15 show the synoptic diagram according to transmitter and receiver in the resistivity prospecting device of the utility model respectively.Be noted that this two figure only is that mode through functional module shows main modular wherein, does not represent concrete physical arrangement module.

In Figure 14; GPS module (1) is transmitted the time service synchronizing information through serial ports to pseudo random signal generator (2); Pseudo random signal generator (2) can be exported the m sequence or the contrary Repeated m-Sequences of different rank, different frequency as required; Collocating LCD is used to show transmitter signal type, parameter and state, and pseudo random signal generator (2) is accomplished the storage of data message simultaneously, and controlling and driving and protection module (3).Driving circuit is used for the pseudo-random sequence that produces is driven IPM (5) work in driving and the protection module (3), and holding circuit is used to protect the safety of total system.Temperature control system (4) is monitored the transmitter temperature inside constantly, and machine even closing machine reset after surpassing predetermined value.IPM (5) will export conversion of signals and become to be used for the current signal of resistivity prospecting and carry electric current to sender electrode AB (6).Supply module (7) is for integrated circuit board provides low-tension supply, and for IPM (5) required high pressure is provided.

In Figure 15; Wherein, GPS module (8) is transmitted the time service synchronizing information through serial ports to pseudo random signal generator (9); Realize precisely synchronously and keep accurate homophase that pseudo random signal generator (9) is exported the m sequence of identical exponent number with transmitter, same frequency as required with the pseudo-random sequence of transmitter; Receiving electrode MN (10) receives the potential difference (PD) that transmits through underground medium; Pass through pre-amplifying module (11) then the electromagnetic signal that receives is carried out preliminary amplification; And, through accurate amplification module (13) signal of filtering noise is carried out the accurate amplification of low noise again through the industrial frequency noise of filtering and trap module (12) filter away high frequency noise and system; Autocorrelator (14) is realized the auto-correlation computation of pseudo random signal; Cross-correlator (15) is realized pseudo random signal and the computing cross-correlation that receives signal; The one FFT transducer (16), the 2nd FFT transducer (17) carry out time-frequency conversion to auto-correlation result and cross correlation results respectively; Frequency response maker (18) computing obtains removing the earth system frequency response after recording geometry influences; The earth system frequency response obtains the complex resistivity spectrum of the earth system through complex resistivity spectrum maker (19); Match device (20) can obtain the sight-reading parameter according to two Coles-Cole's model fitting; Inverter (21) carries out joint inversion and obtains true spectrum parameter, thereby obtains the useful parameter information of geophysics.

Claims (2)

1. a receiver that is used for resistivity prospecting is characterized in that said receiver comprises GPS module (8), pseudo random signal generator (9), receiving electrode MN (10), pre-amplifying module (11), filtering and trap module (12), accurate amplification module (13), autocorrelator (14), cross-correlator (15), a FFT transducer (16), the 2nd FFT transducer (17), frequency response maker (18), complex resistivity spectrum maker (19), match device (20) and inverter (21);

Wherein, GPS module (8) is transmitted the time service synchronizing information through serial ports to pseudo random signal generator (9); Realize precisely synchronously and keep accurate homophase that pseudo random signal generator (9) is exported the m sequence of identical exponent number with transmitter, same frequency as required with the pseudo-random sequence of transmitter; Receiving electrode MN (10) receives the potential difference (PD) that transmits through underground medium; Pass through pre-amplifying module (11) then the electromagnetic signal that receives is carried out preliminary amplification; And, through accurate amplification module (13) signal of filtering noise is carried out the accurate amplification of low noise again through the industrial frequency noise of filtering and trap module (12) filter away high frequency noise and system; Autocorrelator (14) is realized the auto-correlation computation of pseudo random signal; Cross-correlator (15) is realized pseudo random signal and the computing cross-correlation that receives signal; The one FFT transducer (16), the 2nd FFT transducer (17) carry out time-frequency conversion to auto-correlation result and cross correlation results respectively; Frequency response maker (18) computing obtains removing the earth system frequency response after recording geometry influences; The earth system frequency response obtains the complex resistivity spectrum of the earth system through complex resistivity spectrum maker (19); Match device (20) obtains the sight-reading parameter according to two Coles-Cole's model fitting, and inverter (21) carries out joint inversion and obtains true spectrum parameter; Thereby obtain geophysical parameters information, and carry out real time data graphic presentation and storage.

2. a resistivity prospecting system is characterized in that handling to the received signal through transmitter transmission signal and receiver,

Said transmitter comprises global position system GPS (Global Positioning System) module (1), pseudo random signal generator (2), driving and protection module (3), SPM IPM (Intelligent Power Modules) (5), temperature control modules (4) and supply module (7) and sender electrode AB (6); Wherein, GPS module (1) is transmitted the time service synchronizing information through serial ports to pseudo random signal generator (2), accomplishes the storage of data message, and controlling and driving and protection module (3); The m sequence of different rank, different clock frequencies exported as required by pseudo random signal generator (2) or against pseudo-random sequences such as Repeated m-Sequences, collocating LCD is used to show transmitter signal type, parameter and state.Drive and protection module (3) driving IPM (5) work, holding circuit is used to protect the safety of total system; Temperature control system (4) monitoring transmitter temperature inside, machine or closing machine reset after surpassing predetermined value; IPM (5) will export conversion of signals and become to be used for the current signal of resistivity prospecting and carry electric current to sender electrode AB (6); Supply module (7) is for integrated circuit board provides low-tension supply, and for IPM (5) required high pressure is provided;

Said receiver comprises GPS module (8), pseudo random signal generator (9), receiving electrode MN (10), pre-amplifying module (11), filtering and trap module (12), accurate amplification module (13), autocorrelator (14), cross-correlator (15), a FFT transducer (16), the 2nd FFT transducer (17), frequency response maker (18), complex resistivity spectrum maker (19), match device (20) and inverter (21); Wherein, GPS module (8) is transmitted the time service synchronizing information through serial ports to pseudo random signal generator (9); Realize precisely synchronously and keep accurate homophase that pseudo random signal generator (9) is exported the m sequence of identical exponent number with transmitter, same frequency as required with the pseudo-random sequence of transmitter; Receiving electrode MN (10) receives the potential difference (PD) that transmits through underground medium; Pass through pre-amplifying module (11) then the electromagnetic signal that receives is carried out preliminary amplification; And, through accurate amplification module (13) signal of filtering noise is carried out the accurate amplification of low noise again through the industrial frequency noise of filtering and trap module (12) filter away high frequency noise and system; Autocorrelator (14) is realized the auto-correlation computation of pseudo random signal; Cross-correlator (15) is realized pseudo random signal and the computing cross-correlation that receives signal; The one FFT transducer (16), the 2nd FFT transducer (17) carry out time-frequency conversion to auto-correlation result and cross correlation results respectively; Frequency response maker (18) computing obtains removing the earth system frequency response after recording geometry influences; The earth system frequency response obtains the complex resistivity spectrum of the earth system through complex resistivity spectrum maker (19); Match device (20) obtains the sight-reading parameter according to two Coles-Cole's model fitting, and inverter (21) carries out joint inversion and obtains true spectrum parameter; Thereby obtain geophysical parameters information, and carry out real time data graphic presentation and storage.

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