CN106125145A - Mt weighting function identification method and system based on broadband LFM driving source - Google Patents

Abstract

The invention discloses a kind of mt weighting function identification method and system based on broadband LFM driving source, the present invention uses broadband LFM driving source, current waveform and the earth response voltage under broadband linear FM signal to the broadband linear FM signal launched carry out real-time synchronization collection, utilize the mt weighting function identification model of foundation afterwards, determine that according to current waveform the response voltage in convolution inverse operator and corresponding moment is calculated mt impulse response, it is achieved the fine identification of mt impulse response.Compared with traditional bipolar square wave driving source and pseudorandomcode driving source, the broadband linear FM signal that the present invention uses has bandwidth, spectrum density is big, frequency energy is uniform, the feature of inverse operator characteristic good, random noise can effectively be suppressed by identification process with organized noise, thus significantly improve the identification precision of mt impulse response, improve detection signal to noise ratio.

Description

Mt weighting function identification method and system based on broadband LFM driving source

Technical field

The present invention relates to field of geophysical exploration, be more particularly to a kind of the earth based on broadband LFM driving source electricity Magnetic field impulse response discrimination method and system.

Background technology

The energy is the lifeblood that a country depends on for existence and development, does not has any modern civilization of the energy all will not know where to begin. China's coal resource enriches, but petroleum resources wretched insufficiency, detectivity is weak, and stable yields difficulty is bigger.On January 26th, 2016 Chinese stone Oil group economy Institute for Research and Technology has issued " domestic and international gas industries development report in 2015 ", and report is pointed out, 2015, China Crude oil consumption sustainable growth, external dependence degree head breaks 60%, reaches 60.6%.Net oil import 3.28 hundred million tons, increases 6.4%, speed increasing ratio is high 0.6 percentage point for last year.

Positive so-called " a workman must first sharpen his tools if he is to do his work well ", improves existing exploration engineering, promotes geology equipment, realization " attack deeply look for blind " becomes the key point reducing China's external oil gas interdependency.As the important means of " attack deeply look for blind ", ground It is many that electromagnetic surveying has available physical parameter, measures key element and enriches, and the feature such as applied range, and its field source device form is many Sample, has broken away from the space constraint of conventional detection, it is possible to obtain the more rich geological information about geoelectric cross section architectural feature.

The most common surface em detection driving source has the bipolar square wave of dutycycle 100%, bipolarity trapezoidal wave, double Polarity triangular wave and bi-polar half sine wave, recently as the development of coded excitation current technique, based on pseudo-random sequence Encoding detection technical research also achieve certain achievement.But driving source is as the input signal of off-line identification, should ensure that can All mode of Persistent Excitation system, i.e. driving source bandwidth are sufficiently large relative to observation system bandwidth, guarantee identification Quality and precision.From this view, the periodic signal such as the most common bipolar square wave is single due to frequency, generally requires and sweeps Taking place frequently and penetrate, man-hour is long, and efficiency is low；Although the power spectral density of the driving source of pseudo-random sequence is approached white in certain frequency band range Noise characteristic, but its in whole frequency band range according to sinc²Function is decayed, and its power spectrum is discrete, and spectrum density is subject to The impact of exponent number, code check is relatively big, wayward.

It addition, in surface em detects, bigger investigation depth often means that reception and transmission range farther out, at driving source In the case of power limited, the amplitude of significant response signal is the lowest, is even flooded by noise.Therefore to ensure big receipts Send out away from time can obtain preferably identification effect, it is necessary to design optimal excitation source and corresponding discrimination method, with in identification Noise is suppressed by journey, improves response signal to noise ratio, improve the identification quality of mt impulse response.From this angle Seeing, if using bipolarity periodic signal as driving source, being then difficult to the noise component(s) launched beyond frequency in identification process Suppress；If using pseudo-random sequence as driving source, then it is difficult to the noise component(s) launched at code check in identification process Suppressing, cause the selection launching code check limited, even occurring in some strong jamming work areas cannot the situation of identification.

Summary of the invention

The technical problem to be solved in the present invention is how to improve degree of accuracy and the efficiency of surface em detection, improves detection Signal to noise ratio.

In order to solve above-mentioned technical problem, on the one hand the invention provides a kind of the earth based on broadband LFM driving source Electromagnetic pulse response discrimination method, said method comprising the steps of:

S1, utilize broadband LFM driving source launch broadband linear FM signal；

The current waveform of broadband linear FM signal described in S2, Real-time Collection, and utilize described current waveform to determine pleat Long-pending inverse operator；

S3, Real-time Collection big response voltage under described broadband linear FM signal；

S4, foundation are based on convolution inverse operator, response voltage and the mt impulse response of mt impulse response Identification model, according to described mt weighting function identification model, utilizes the described convolution inverse operator that described step S2 determines And the response voltage in corresponding moment that described step S3 gathers is calculated described mt impulse response.

Preferably, described method is further comprising the steps of:

S5, repeat described step S2-S4, determine multiple described mt impulse response, and to multiple described greatly Ground electromagnetic pulse response carries out Coherent addition and determines final mt impulse response.

Preferably, utilize formula below to multiple described mt impulse response memory Coherent additions:

$\stackrel{\‾}{g}\left(t\right)=\frac{1}{N}\underset{i=1}{\overset{N}{\Σ}}{g}_i\left(t\right)$

In formula,For described final mt impulse response, g_iT () is described mt impulse response, N table Show the quantity of described mt impulse response.

Preferably, described current waveform is expressed as:

$s\left(t\right)=A\·rect\left(\frac{t-0.5\mathrm{\τ}}{\mathrm{\τ}}\right)\·sin\left({\mathrm{\πkt}}^2\right)$

In formula, s (t) is described current waveform, and A is the modulation amplitude of described broadband LFM driving source, and τ is described wideband With the time width of linear FM signal, k is the modulation slope of described broadband LFM driving source；For rectangular function.

Preferably, described mt weighting function identification model is:

F (t) * r (t)=δ (t) * g (t)+f (t) * n (t)=g (t)+f (t) * n (t)

In formula, f (t) is described convolution inverse operator, and r (t) is described response voltage, and δ (t) is unit impulse signal, g (t) For described mt impulse response, n (t) is interference noise.

Preferably, described convolution inverse operator meets equation below:

F (t) * s (t)=δ (t)

In formula, s (t) is described current waveform.

Preferably, described convolution inverse operator utilizes wiener Deconvolution to solve.

Preferably, described step S1 specifically includes step:

Determine bandwidth and the duration of described broadband LFM driving source, and generate driving signal according to described bandwidth and duration, The broadband linear driving described broadband LFM driving source to launch corresponding bandwidth and duration under the control of described driving signal is adjusted Frequently signal.

On the other hand present invention also offers a kind of system utilizing said method to carry out mt weighting function identification, Described system includes that signal transmitter unit, convolution inverse operator determine unit, response voltage acquisition unit and mt pulse In response to determining that unit；

Described signal transmitter unit is used for utilizing broadband LFM driving source to launch broadband linear FM signal；

Described convolution inverse operator determine unit for the current waveform of broadband linear FM signal described in Real-time Collection, and Described current waveform is utilized to determine convolution inverse operator；

Described response voltage acquisition unit is used for Real-time Collection response under described broadband linear FM signal greatly Voltage；

Described mt impulse response determines that unit is for setting up based on convolution inverse operator, response voltage and the earth electricity The mt weighting function identification model of magnetic field impulse response, and utilize described convolution inverse operator to determine the described pleat that unit determines The response voltage in the corresponding moment of long-pending inverse operator and described response voltage acquisition unit collection is calculated described mt Impulse response.

Preferably, described system also includes Coherent addition unit, and described Coherent addition unit is for by calculated many Individual described mt impulse response carries out Coherent addition and determines final mt impulse response.

The invention provides a kind of mt weighting function identification method and system based on broadband LFM driving source, The present invention uses broadband LFM driving source, and current waveform and the earth to the broadband linear FM signal launched are at wideband Carry out real-time synchronization collection with the response voltage under linear FM signal, utilize the mt weighting function identification of foundation afterwards According to current waveform, model, determines that the response voltage in convolution inverse operator and corresponding moment is calculated mt pulse and rings Should, it is achieved the fine identification of mt impulse response.Encourage with traditional bipolar square wave driving source and pseudorandomcode Source is compared, and the broadband linear FM signal that the present invention uses has bandwidth, spectrum density is big, frequency energy is uniform, inverse operator The feature of characteristic good, can effectively suppress with organized noise random noise in identification process, thus significantly improve The identification precision of mt impulse response, improves detection signal to noise ratio.The technical scheme steps that the present invention provides is simple, meter Calculation amount is little, so being effectively increased the efficiency of detection.It addition, the present invention has carried out secondary compacting by Coherent addition to noise, Further increasing identification precision and the detection signal to noise ratio of mt impulse response.

Accompanying drawing explanation

In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only this Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to Other accompanying drawing is obtained according to these accompanying drawings.

Fig. 1 is the flow chart of the mt weighting function identification method based on broadband LFM driving source of the present invention；

Fig. 2 is that the mt impulse response based on broadband LFM driving source of a preferred embodiment in the present invention is distinguished The flow chart of knowledge method；

Fig. 3 A, 3B are the time-frequency figures of broadband LFM driving source in the present invention；

Fig. 4 is the bipolar square wave oscillogram as convolution inverse operator during driving source；

Fig. 5 is the m stochastic ordering train wave oscillogram as convolution inverse operator during driving source；

Fig. 6 is the oscillogram of the convolution inverse operator of broadband LFM driving source；

Fig. 7 is broadband linear FM signal stepwise schematic views in the present invention；

Fig. 8 is the result schematic diagram utilizing traditional method to carry out mt weighting function identification；

Fig. 9 is the result schematic diagram utilizing the method for the present invention to carry out mt weighting function identification；

Figure 10 is the Identification Errors schematic diagram utilizing traditional method to carry out mt weighting function identification；

Figure 11 is the Identification Errors schematic diagram utilizing the method for the present invention to carry out mt weighting function identification；

Figure 12 is the mt impulse response based on broadband LFM driving source of another preferred embodiment in the present invention Current waveform schematic diagram in discrimination method；

Figure 13 is the mt impulse response based on broadband LFM driving source of another preferred embodiment in the present invention Discrimination method responds the waveform diagram of voltage；

Figure 14 is the mt impulse response based on broadband LFM driving source of another preferred embodiment in the present invention The identification result schematic diagram that discrimination method obtains.

Detailed description of the invention

With embodiment, the present invention is described in further detail below in conjunction with the accompanying drawings.Following example are used for this is described Bright, but can not be used for limiting the scope of the present invention.

A kind of mt weighting function identification method based on broadband LFM driving source, as it is shown in figure 1, described method Comprise the following steps:

S1, utilize broadband LFM driving source launch broadband linear FM signal；

The current waveform of broadband linear FM signal described in S2, Real-time Collection, and utilize described current waveform to determine pleat Long-pending inverse operator；

S3, Real-time Collection big response voltage under described broadband linear FM signal；

S4, foundation are based on convolution inverse operator, response voltage and the mt impulse response of mt impulse response Identification model, utilizes described convolution inverse operator that described step S2 determines and the response in the corresponding moment that described step S3 gathers Voltage is calculated described mt impulse response.

Compared with traditional bipolar square wave driving source and pseudorandomcode driving source, the wideband band wire that the present invention uses Property FM signal have that bandwidth, spectrum density be big, frequency energy uniformly, the feature of inverse operator characteristic good, in identification process Random noise effectively can be suppressed with organized noise, thus significantly improve the identification essence of mt impulse response Degree, improves detection signal to noise ratio.The technical scheme steps that the present invention provides is simple, and amount of calculation is little, so being effectively increased detection Efficiency.

Further, described method is further comprising the steps of:

S5, repeat described step S2-S4, determine multiple described mt impulse response, and to multiple described greatly Ground electromagnetic pulse response carries out Coherent addition and determines final mt impulse response.

Utilize above-mentioned steps S5 that noise has been carried out secondary compacting, further increasing distinguishing of mt impulse response Know precision and detection signal to noise ratio.Preferably, utilize formula below that multiple described mt impulse responses carry out Coherent addition:

$\stackrel{\‾}{g}\left(t\right)=\frac{1}{N}\underset{i=1}{\overset{N}{\Σ}}{g}_i\left(t\right)$

In formula,For described final mt impulse response, g_iT () is described mt impulse response, N table Show the quantity of described mt impulse response.

Below the compacting of above-mentioned secondary is described in detail:

In practical operation, the broadband LFM signal transmitting that single is complete often continues hundreds of milliseconds time to the several seconds, When carrying out field operation, for single group transmitting-receiving point, transmitter often circulates transmitting n times signal, and the value of N is adjusted along with operating mode Whole, general short transmitting-receiving value of N when, high s/n ratio is less than normal, and long transmitting-receiving value of N when, low signal-to-noise ratio is bigger than normal.

Therefore, firstly the need of data being carried out point before utilizing mt weighting function identification model to carry out off-line identification Section, for broadband linear FM signal often with LFM time a width of cycle divide, for the earth response voltage wave Shape, in order to comprise the earth response later stage trend, needs wide when LFM on the basis of carry out a time delay sample, delay time Generally 1～2 second.Fig. 7 is data sectional schematic diagram.Respectively to N to the waveform of broadband linear FM signal and the earth Response voltage waveform carries out identification and i.e. can get N bar mt pulse respond g_iT (), carries out phase to N bar response curve Close superposition, noise can be carried out secondary compacting, obtain the fine identification result of mt impulse responseIts process can Describe with following formula:

$\stackrel{\‾}{g}\left(t\right)=\frac{1}{N}\underset{i=1}{\overset{N}{\Σ}}{g}_i\left(t\right)$

In theory, for white Gaussian noise, n times superposition can make signal to noise ratio improve N times, but generally there are relatively in view of work area Strong human noise, therefore actual signal to noise ratio promotes effect and is often below this level.

Further, the described current waveform in step S2 is expressed as:

$s\left(t\right)=A\·rect\left(\frac{t-0.5\mathrm{\τ}}{\mathrm{\τ}}\right)\·sin\left({\mathrm{\πkt}}^2\right)$

In formula, s (t) is described current waveform, and A is the modulation amplitude of described broadband LFM driving source, and τ is described wideband With the time width of linear FM signal, k is the modulation slope of described broadband LFM driving source.

For rectangular function, and meet

The amplitude-frequency characteristic of band a width of B=k τ, LFM of s (t) current waveform is approximately window function, i.e. in the range of bandwidth B Each frequency energy is uniform, and Fig. 3 A, 3B are A=20；B=5000Hz；The time-frequency figure of the broadband LFM signal of τ=0.1s.From figure The amplitude-frequency characteristic of this LFM signal visible is evenly distributed in bandwidth 0-5000Hz substantially.

Further, the described mt weighting function identification model in step S4 is:

F (t) * r (t)=δ (t) * g (t)+f (t) * n (t)=g (t)+f (t) * n (t)

In formula, f (t) is described convolution inverse operator, and r (t) is described response voltage, and δ (t) is unit impulse signal, g (t) For described mt impulse response, n (t) is interference noise.Described convolution inverse operator meets equation below:

F (t) * s (t)=δ (t)

In formula, s (t) is described current waveform.Described convolution inverse operator utilizes wiener Deconvolution to solve, and its thought is Make the output of f (t) * s (t) and energy error Q of desired output δ (t) minimum under least squares sense.

Building process to mt weighting function identification model carries out message introduction below:

The earth can be equivalent to a linear time-varying LTI system, and the response of its electromagnetic pulse is g (t), then the response electricity of the earth The convolution of current waveform s (t) and electromagnetic pulse response g (t) that pressure r (t) can be expressed as broadband linear FM signal is:

R (t)=s (t) * g (t)

In view of interference noise n (t):

R (t)=s (t) * g (t)+n (t) (1)

Mt weighting function identification process based on convolution model is exactly convolution one inverse operator (1) formula both sides while F (t), f (t) meet f (t) * s (t)=δ (t), and wherein δ (t) is unit impulse signal.

F (t) * r (t)=δ (t) * g (t)+f (t) * n (t)=g (t)+f (t) * n (t) (2)

(2) g (t) on the right side of formula is preferable mt impulse response, and f (t) * n (t) is noise component(s).

F (t) is unsatisfactory, i.e. f (t) * s (t) ≈ δ (t), and this undesirable property can reduce identification essence to a certain extent Degree, therefore (2) formula is rewritable is:

F (t) * r (t)=g (t)+f (t) * n (t)+e (t) (3)

(3) in formula, e (t) characterizes the error noise that the undesirable property of inverse operator introduces.

Therefore, in order to ensure good identification precision, it is desirable to noise component(s) f (t) * n (t)+e (t) is the least, this is just Need:

1) noise can effectively be suppressed by inverse operator f (t)；

2) inverse operator characteristic good, i.e. f (t) * s (t) enough approach unity impulse signals.

So when selecting driving source, can be by comparing convolution result and the ideal unitary impulse of inverse operator and driving source The inverse operator characteristic of each driving source is analyzed by the approximation ratio of signal.Bipolar with 100% conventional dutycycle below As a example by property square wave and m-sequence, carry out inverse operator Character Comparison with broadband LFM signal.

(1) the inverse operator characteristic pair of 100% dutycycle bipolar square wave in broadband LFM signal and conventional driver source Ratio, is illustrated in figure 4 100% dutycycle bipolar square wave as the f (t) * s (t) during driving source, it can be seen that 100% duty More unsatisfactory than the inverse operator characteristic of bipolar square wave, there is obvious secondary lobe.

(2) broadband LFM signal and m-sequence are inverse operator Character Comparison during driving source, and being illustrated in figure 5 m-sequence is F (t) * s (t) during driving source, it can be seen that the inverse operator characteristic relatively bipolar square wave of m-sequence improves to some extent, but still manages not Think.

Fig. 6 is that broadband LFM signal is as the f (t) * s (t) during driving source, it can be seen that the signal conduct of broadband LFM During driving source, the preferable impulse signal of its f (t) * s (t) almost, therefore select broadband LFM signal as driving source, it is possible to Reduce the error noise in identification process.

Further, as in figure 2 it is shown, described step S1 specifically includes step:

Determine bandwidth and the duration of described broadband LFM driving source, and generate driving signal according to described bandwidth and duration, The broadband linear driving described broadband LFM driving source to launch corresponding bandwidth and duration under the control of described driving signal is adjusted Frequently signal.

Broadband linear frequency modulation (LFM) signal that the said method of the present invention uses is a kind of big Timed automata signal, Its frequency presses linear rule change in pulse width, it is ensured that its amplitude-frequency characteristic is a constant in effective bandwidth, therefore LFM signal has that bandwidth, spectrum density be big, the uniform feature of frequency energy, meets broadband excitation source in the electromagnetic surveying of ground Requirement.It addition, its special amplitude-frequency characteristic determines identification process and presents broad stop-band, i.e. can be to each frequency content Noise effectively suppress, it is achieved the high accuracy identification under low signal-to-noise ratio.

For proving that the method for the invention can carry out the identification of higher precision to mt impulse response further, this Invention has carried out one group of contrast test, such as Fig. 8,9 be to use the mt arteries and veins of method as described in traditional method and this patent respectively Punching response identification result.Figure 10,11 it is to use the mt impulse response of method described in traditional method and this patent to distinguish respectively Knowing error, its calculation expression is:

$e=\frac{g^{\′}-g}{g}\×100\%$

Wherein e represents Identification Errors, and g ' represents mt weighting function identification result, g representation theory mt arteries and veins Punching response.Can be clearly seen that, method described in this patent can compacting effective to interference noise, significantly improve mt arteries and veins The identification precision of punching response.

A concrete case is described below, said method and acquirement effect is illustrated:

Test site: Xinghe County, Inner Mongolia Autonomous Region is domestic, specially Xiguo county of village of 50 No. three villages, area just outside a city gate, Xinghe County town Die young south, village of village (binary Jing Cun village east).Survey line north and south end longitude and latitude be respectively 40 ° 48 ' 13.83 " north, 113 ° of 53'56.66 " east and 40 ° of 50'16.55 " north, 113 ° of 51'50.76 " east, total survey line length 4800m.

The implementation case makes operate in aforementioned manners.Launch point coordinate is 0-240, and response receives point coordinates and is 2320-2360, reception and transmission range 2220m, systematic sampling rate 16KHz, emission current 33A, earth resistance 15 Ω, select emission parameter B=5KHz, τ=1s.

Figure 12 Yu Figure 13 is respectively the current waveform of broadband linear FM signal and the waveform diagram of response voltage, figure 14 give and utilize the said method of the present invention to carry out the mt weighting function identification result schematic diagram that identification obtains, and do , wherein there is spike at, referred to as air wave at curve section start in smoothing processing, this is to pass in atmosphere when initial transmitting The electromagnetic wave broadcast causes, and belongs to normal phenomenon.Through contrasting with the response results of other exploitation method, it was demonstrated that the present invention's The identification result accuracy that method determines is high.

The invention also discloses one corresponding to said methods to utilize said method to carry out mt impulse response to distinguish The system known, described system includes that signal transmitter unit, convolution inverse operator determine unit, response voltage acquisition unit and the earth Electromagnetic pulse is in response to determining that unit；Described signal transmitter unit is used for utilizing broadband LFM driving source to launch broadband linear and adjusts Frequently signal；Described convolution inverse operator determine unit for the current waveform of broadband linear FM signal described in Real-time Collection, and Described current waveform is utilized to determine convolution inverse operator；Described response voltage acquisition unit is used for Real-time Collection at described wideband band wire Big response voltage under property FM signal；Described mt impulse response determines that unit is for setting up based on convolution inverse Son, response voltage and the mt weighting function identification model of mt impulse response, and utilize described convolution inverse Son determines described convolution inverse operator that unit determines and the response electricity in the corresponding moment that described response voltage acquisition unit gathers Pressure is calculated described mt impulse response.

Further, described system also includes Coherent addition unit, and described Coherent addition unit is for by calculated Multiple described mt impulse responses carry out Coherent addition and determine final mt impulse response.

Due to process step and the said method one_to_one corresponding of said apparatus, so no longer the part repeated being gone to live in the household of one's in-laws on getting married State.

Said apparatus or method employing broadband LFM signal are as driving source, to transmitted waveform (i.e. broadband linear frequency modulation The current waveform of signal) carry out synchronize with observation signal (i.e. under described broadband linear FM signal response voltage) greatly Gather, based on mt weighting function identification model, mt impulse response is carried out off-line identification afterwards, finally by Coherent addition carries out secondary compacting to noise, it is achieved the fine identification of mt impulse response.With traditional bipolar square wave Driving source and pseudorandomcode driving source are compared, the broadband LFM signal that the present invention uses have bandwidth, spectrum density big, Frequency energy is uniform, the feature of inverse operator characteristic good, can have random noise with organized noise in identification process Effect compacting, thus significantly improve the identification precision of mt impulse response.Said method or device are particularly suited for low noise Than receiving and dispatching away from geophysics electromagnetism exploration system greatly under environment.

Various embodiments above only in order to technical scheme to be described, is not intended to limit；Although with reference to aforementioned each reality Execute example the present invention has been described in detail, it will be understood by those within the art that: its still can to aforementioned respectively Technical scheme described in embodiment is modified, or the most some or all of technical characteristic is carried out equivalent；And These amendments or replacement, do not make the essence of appropriate technical solution depart from the scope of various embodiments of the present invention technical scheme, its All should contain in the middle of the claim of the present invention and the scope of description.

Claims (10)

1. a mt weighting function identification method based on broadband LFM driving source, it is characterised in that described method bag Include following steps:

S1, utilize broadband LFM driving source launch broadband linear FM signal；

The current waveform of broadband linear FM signal described in S2, Real-time Collection, and utilize described current waveform to determine that convolution is anti- Operator；

S3, Real-time Collection big response voltage under described broadband linear FM signal；

S4, foundation are based on convolution inverse operator, response voltage and the mt weighting function identification of mt impulse response Model, according to described mt weighting function identification model, utilize described convolution inverse operator that described step S2 determines and The response voltage in the corresponding moment that described step S3 gathers is calculated described mt impulse response.

Method the most according to claim 1, it is characterised in that described method is further comprising the steps of:

S5, repeat described step S2-S4, determine multiple described mt impulse response, and to multiple described the earth electricity Magnetic field impulse response carries out Coherent addition and determines final mt impulse response.

Method the most according to claim 2, it is characterised in that utilize formula below that multiple described mt pulses are rung Should carry out Coherent addition:

$\stackrel{\‾}{g}\left(t\right)=\frac{1}{N}\underset{i=1}{\overset{N}{\Σ}}{g}_i\left(t\right)$

In formula,For described final mt impulse response, g_iT () is described mt impulse response, N represents described The quantity of mt impulse response.

Method the most according to claim 1 and 2, it is characterised in that described current waveform is expressed as:

$s\left(t\right)=A\·rect\left(\frac{t-0.5\mathrm{\τ}}{\mathrm{\τ}}\right)\·sin\left({\mathrm{\πkt}}^2\right)$

In formula, s (t) is described current waveform, and A is the modulation amplitude of described broadband LFM driving source, and τ is described wideband band wire The time width of property FM signal, k is the modulation slope of described broadband LFM driving source；For rectangular function.

Method the most according to claim 1 and 2, it is characterised in that described mt weighting function identification model is:

F (t) * r (t)=δ (t) * g (t)+f (t) * n (t)=g (t)+f (t) * n (t)

In formula, f (t) is described convolution inverse operator, and r (t) is described response voltage, and δ (t) is unit impulse signal, and g (t) is institute Stating mt impulse response, n (t) is interference noise.

Method the most according to claim 5, it is characterised in that described convolution inverse operator meets equation below:

F (t) * s (t)=δ (t)

In formula, s (t) is described current waveform.

Method the most according to claim 6, it is characterised in that described convolution inverse operator utilizes wiener Deconvolution to solve.

Method the most according to claim 1 and 2, it is characterised in that described step S1 specifically includes step:

Determine bandwidth and the duration of described broadband LFM driving source, and generate driving signal according to described bandwidth and duration, in institute State and drive the described broadband LFM driving source of lower driving that controls of signal to launch the broadband linear frequency modulation letter of corresponding bandwidth and duration Number.

9. utilizing the method described in any one of claim 1 to 8 to carry out a system for mt weighting function identification, it is special Levying and be, described system includes that signal transmitter unit, convolution inverse operator determine unit, response voltage acquisition unit and the earth electricity Magnetic field impulse is in response to determining that unit；

Described signal transmitter unit is used for utilizing broadband LFM driving source to launch broadband linear FM signal；

Described convolution inverse operator determines that unit, for the current waveform of broadband linear FM signal described in Real-time Collection, and utilizes Described current waveform determines convolution inverse operator；

Described response voltage acquisition unit is used for Real-time Collection response voltage under described broadband linear FM signal greatly；

Described mt impulse response determines that unit is for setting up based on convolution inverse operator, response voltage and mt arteries and veins The mt weighting function identification model of punching response, and the described convolution utilizing described convolution inverse operator to determine that unit determines is anti- The response voltage in the corresponding moment of operator and described response voltage acquisition unit collection is calculated described mt pulse Response.

System the most according to claim 9, it is characterised in that described system also includes Coherent addition unit, described relevant Superpositing unit determines final the earth electricity for calculated multiple described mt impulse responses carry out Coherent addition Magnetic field impulse responds.