CN102053278B - Electrical prospecting method and measuring device - Google Patents

Abstract

The invention discloses an electrical prospecting method and a measuring device. The method comprises the following steps of: transmitting a current waveform serving as an excitation signal with pseudo-random code characteristics to the underground through a transmitter; receiving a voltage signal generated by the excitation signal through a receiver; mathematically processing to obtain a pulse transition function; obtaining an amplitude-frequency curve and a phase frequency curve in a corresponding frequency range through fast Fourier transform; obtaining an amplitude value and a phase value of each frequency point; and obtaining apparent resistivity and phase parameters with geophysical meaning through the parameters. The device comprises a transmitter consisting of a computer, a programmable logic device, a transmitter clock synchronization circuit, a logic sequence generator, a self-sampling processing circuit, a direct current power supply, a drive and protection circuit, a self-sampling filtering circuit and a power supply electrode AB, and a receiver consisting of a filtering and protecting circuit, an amplifying and analog/digital sampling circuit, a programmable logic device and a computer. The device has good anti-interference performance, can perform effective measurement at low power and can be matched with a plurality of sets of equipment to perform measurement simultaneously.

Description

Resistivity prospecting method and measurement mechanism

Technical field

The present invention relates to a kind of resistivity prospecting.Particularly relate to a kind of resistivity prospecting method and measurement mechanism with active source frequency field of strong interference immunity.

Background technology

Non-ferrous metal is used wide and the status is important, is to have the important strategic resource in Chinese national economy and the national defense construction.The contradiction of outlet and iron ore, a large amount of dependence on import of high-end product is more and more outstanding at a low price along with the low value-added nonferrous metal product of China, improve the self-supporting degree of protection of resource, aspect such as support the national economic development and even safeguard national security all more and more need deep, production mine or near and corresponding metallogenic province band carry out the investigation and prospecting of ore deposit, deep, buried ore.

Resistivity prospecting mainly utilizes electric conductivity, induced polarization, magnetic conductivity, dielectricity, piezoelectricity and the shake of material electrical etc., can carry out electrical survey in ground, aerial or ocean now, but still based on the ground resistivity prospecting.The method kind of resistivity prospecting is a lot, divide from the formation mechanism one artificial field source and the natural field source of field source, can be divided into active source electrical method and passive source electrical method two big classes, wherein the application of active source electrical method is more, and its representative method has resistivity method, induced polarization method, mise-a-la-masse method, frequency electromagnetic sounding method, controllable source audio-frequency magnetotelluric magnetic sounding, transient electromagnetic method etc.

Along with the develop rapidly of electronic computation technology, resistivity prospecting method and technology and instrument are more and more, and the U.S., France, Canada, Russia, China etc. all produce various electrical measuring instrument,s.After the last century the eighties, V8, SIROTEM, EM67, VIP, instrument and equipments such as GDP32, IPR-12 that China has introduced the U.S., Canada relevant company were in succession carried out and are looked for the miner to do.Nearly hundred electrical method monographic studies by China during the last ten years and reconnoitre the project practice prove that electrical method is reconnoitred in new round geological prospecting field can obtain good effect.

But present informationization society electromagnetic signal is omnipresent, and industry and life electromagnetic interference (EMI) are serious day by day, and existing electrical measuring instrument, all is difficult to overcome well electromagnetic interference (EMI) and obtains satisfied resistivity prospecting data; On the other hand, along with the exhaustion of face of land resource and the raising of mining technique means, wanting the ore deposit to the deep is the inexorable trend of human social development.Some instrument producers are for the anti-strong electromagnetic performance that improves instrument and improve the resolution of deep layer exploration, taked to strengthen the method and technology of supply current, electromagnetic interference (EMI) not too serious area also obtained some gratifying effects really.But, restricted by factors such as safety and technology, supply current can not infinitely improve, and in the mining area that is just producing, along the line, the humane movable frequent area such as high pressure corridor and city, market town etc. of railway, the method that strengthens supply current still is powerless before powerful stray current interference surface.

Need not big electric current, anti-interference, developing direction that high resolving power is following electrical measuring instrument,, also only so, resistivity prospecting could keep great vitality, could realize the resistivity prospecting in strong electromagnetic district, could improve the resolution of deep layer resistivity prospecting.

Summary of the invention

Technical matters to be solved by this invention is, a kind of strong interference immunity is provided, can under miniwatt, effectively measure, and resistivity prospecting method and the measurement mechanism can more than enough complete equipment measured simultaneously.

The technical solution adopted in the present invention is: a kind of resistivity prospecting method and measurement mechanism, wherein, the resistivity prospecting method, comprise by transmitter and have the current waveform of pseudo-random code characteristic as pumping signal to underground transmission, receiver receives the voltage signal that is produced by pumping signal, obtain impulse response by mathematics manipulation, obtain the amplitude frequency curve and the phase frequency curve of corresponding frequencies section again by fast fourier transform, and obtain range value, the phase value of each frequency, obtain apparent resistivity and phase parameter with geophysics meaning by these parameters.

Described transmission has that the code length of pseudo-random code of current waveform of pseudo-random code characteristic is adjustable, the origin polynomial expression can be selected, bit rate is adjustable, start-phase is adjustable, the pumping signal that is sent is from first phase, the current waveform that will have pseudo-random characteristics according to code length, origin polynomial expression, bit rate and the start-phase set sends successively, with 2 ⁿ-1 is the cycle, n be one greater than 0 less than 20 integer.

Described mathematical processes is as follows:

$y\left(t\right)={\∫}_{-\∞}^{+\∞}G(t-\mathrm{\σ})*u\left(\mathrm{\σ}\right)*\mathrm{d\σ}+e\left(t\right)$

Wherein: y (t) is the measuring-signal that instrument obtains, i.e. measuring-signal between the receiving electrode MN, and G (t-σ) is an impulse response, and u (σ) is a power supply signal, is pseudo random signal, and e (t) is a undesired signal;

Measuring-signal convolution power supply signal u (σ) with instrument obtains is reconstructed y (t), obtains:

Because the power supply signal that uses is a pseudo-random code, i.e. pulse signal, therefore

Because the correlativity of undesired signal and pseudo-random code is very little, so can be approximated to:

It is the undesired signal of convolution.

When n was enough big, useful signal with the ratio of the enlargement factor of noise was: (2 like this ⁿ-1)/and 2n, thus enough signal-to-noise characteristic obtained by changing n, thus obtain more to approach the impulse response of true value.

The described parameter that obtains the geophysics meaning is:

The pumping signal that sends is done the impulse response of the pumping signal that auto-correlation processing obtains sending, do the impulse response that cross correlation process obtains received signal to received signal, impulse response to the pumping signal that sends is done fast fourier transform, obtain the real part and the imaginary part of signal under each frequency, thereby obtain the amplitude-frequency characteristic curve and the phase frequency characteristic curve of the pumping signal that sends respectively; In like manner, impulse response is to received signal done fast fourier transform, obtains the amplitude-frequency characteristic curve and the phase frequency characteristic curve of received signal; Deduct the phase frequency characteristic curve respective tones point value of the pumping signal of transmission with each value of frequency point of the phase frequency characteristic curve of received signal, obtain the absolute phase values φ of each frequency _sWith each value of frequency point of amplitude-frequency characteristic curve of received signal value, multiply by electrode coefficient K again and promptly obtain apparent resistivity value ρ divided by the corresponding frequency of amplitude-frequency characteristic curve of the pumping signal that sends _s=K * U/I.

The current waveform minimum frequency of the pumping signal that transmitter sends is 2 ^-10Hz, maximum frequency are 2 ²⁰Hz.

Wherein, the measurement mechanism that is used for the resistivity prospecting method, include transmitter and receiver, described transmitter comprises: the transmitter scale programmable logic device links to each other with the input and output of transmitter control computer, the output of transmitter scale programmable logic device links to each other with the logical sequence generator, the output of described logical sequence generator connects driving and holding circuit, the output of described driving and holding circuit is connected to electrodes of A B, the output of described driving and holding circuit is also successively by reaching the input end that is connected to the transmitter scale programmable logic device from the sampling processing circuit from the sampling filter circuit, described transmitter scale programmable logic device also connects the transmitter clock synchronizing circuit, and described driving and holding circuit are by DC power supply;

Described receiver comprises: will be from the input signal of receiving electrode successively by exporting to the receiver control computer behind filtering and holding circuit, amplification and AD sample circuit and the receiver scale programmable logic device, and described receiver scale programmable logic device also connects the receiver clock synchronizing circuit.

Described transmitter clock synchronizing circuit comprises: the external gps antenna of Chuan Jie transmitter, transmitter GPS module, transmitter buffer circuit and the synchronous output line of transmitter successively, wherein, the output terminal of described transmitter buffer circuit and transmitter scale programmable logic device.

Described logical sequence generator comprises: the control signal level shifting circuit links to each other with the output terminal of transmitter scale programmable logic device; the output terminal of described control signal level shifting circuit connects isolates and positive and negative inverting circuit, and the output of described isolation and positive and negative inverting circuit connects driving and holding circuit.

Described driving and holding circuit comprise: first sample resistance, over-current detection, buffer circuit, high-voltage switch drive circuit, High Speed I GBT circuit, second sample resistance, wherein, described first sample resistance is serially connected in the positive voltage terminal of direct supply, the two ends of sample resistance are connected to the input end of over-current detection circuit, the output terminal of described over-current detection circuit is connected to the input end of buffer circuit, and the output terminal of described buffer circuit is received the circuit input end of transmitter scale programmable logic device; The input end of described high-voltage switch drive circuit connects the circuit output end of logical sequence generator, the output terminal of high-voltage switch drive circuit is received the control end of High Speed I GBT circuit, and the output terminal of High Speed I GBT circuit is connected on the electrodes of A B after by second sample resistance; Two of second sample resistance terminates to from the sampling filter circuit) input end.

Described amplifying circuit, low pass and notch filter circuit and the AD sample circuit that is connected in series successively that comprise from the sampling processing circuit, wherein, the input end of described amplifying circuit connects the output terminal from the sampling filter circuit, and the output terminal of described AD sample circuit connects the input end of transmitter scale programmable logic device.

Described receiver clock synchronizing circuit comprises the external gps antenna of receiver, receiver GPS module, clock synchronization line, receiver buffer circuit, the external gps antenna of described receiver is connected to the input end of receiver GPS module, the output terminal of described receiver GPS module is connected to one tunnel input of receiver buffer circuit, described clock synchronization line is connected to another road input of receiver buffer circuit, and the output signal of described receiver buffer circuit is connected on the receiver scale programmable logic device.

Resistivity prospecting method of the present invention and measurement mechanism, described method is carried out mathematics manipulation with received signal and power supply signal, successfully realized jamproof target, and the characteristic of pseudo-random code also makes this system effectively measure under miniwatt, and can measure simultaneously by more than enough complete equipment.Described measurement mechanism is in high mountain jungle area and the traffic under-developed area is low because of power, equipment is light, mobility strong, can work simultaneously by many instruments, and this just generally investigates fast for large tracts of land and dark limit, production mining area portion resource exploration provides effective means.The present invention has following characteristics:

1. the pseudo-random code waveform of transmitter transmission can be selected arbitrarily to determine according to different code lengths, origin polynomial expression, bit rate and first phase, can select suitable pseudo-random code waveform to obtain satisfactory SN ratio at the disturbed condition of different regions, thereby the fine compacting production of energy mine industrial electro magnetic interference can be carried out exploration in dark limit, production mine portion;

2. many measurement mechanisms of areal work can be selected different code lengths and the work of origin polynomial expression, thereby have solved the electrical measuring instrument, problem that can not work simultaneously of interference source each other;

3. the transmitter and receiver precise synchronization has guaranteed that start-phase is identical under each frequency, can realize amplitude, the absolute phase of a plurality of frequencies, the accurate measurement of relative phase, helps the character of more accurate differentiation anomaly source, looks for the ore deposit;

4. the Anti-interference Design of measurement mechanism effectively reduces the power of active source, realize lighting and can send multimachine reception working method by a machine, can satisfy rapid large-area and reconnoitre, particularly reduce labour intensity, improve work efficiency simultaneously in western desert and high mountain area.

Description of drawings

Fig. 1 is transmitter supply waveform figure of the present invention;

Fig. 2 is a transmitter schematic block diagram of the present invention;

Fig. 3 is a receiver schematic block diagram of the present invention;

Fig. 4 is a transmitter clock synchronizing circuit block diagram;

Fig. 5 is a logical sequence generator circuit block diagram;

Fig. 6 drives and the holding circuit block diagram;

Fig. 7 is from the sampling processing circuit block diagram;

Fig. 8 is a receiver clock synchronizing circuit block diagram.

Embodiment

Below in conjunction with embodiment and accompanying drawing resistivity prospecting method of the present invention and measurement mechanism are made a detailed description.

Resistivity prospecting method of the present invention, comprise by transmitter and have the current waveform of pseudo-random code characteristic as pumping signal to underground transmission, receiver receives the voltage signal that is produced by pumping signal, obtain impulse response by mathematics manipulation, obtain the amplitude frequency curve and the phase frequency curve of corresponding frequencies section again by fast fourier transform, and obtain range value, the phase value of each frequency, thereby obtain apparent resistivity and phase parameter with geophysics meaning by these parameters.

Described transmission has that the code length of pseudo-random code of current waveform of pseudo-random code characteristic is adjustable, the origin polynomial expression can be selected, bit rate is adjustable, start-phase is adjustable, the pumping signal that is sent is from first phase, the current waveform that will have pseudo-random characteristics according to code length, origin polynomial expression, bit rate and the start-phase set sends successively, with 2 ⁿ-1 is the cycle, n be one greater than 0 less than 20 integer.

Described mathematical processes is as follows:

$y\left(t\right)={\∫}_{-\∞}^{+\∞}G(t-\mathrm{\σ})*u\left(\mathrm{\σ}\right)*\mathrm{d\σ}+e\left(t\right)$

Wherein: y (t) is the measuring-signal that instrument obtains, i.e. measuring-signal between the receiving electrode MN, and G (t-σ) is an impulse response, and u (σ) is a power supply signal, is pseudo random signal, and e (t) is a undesired signal;

With measuring the signal convolution power supply signal u (σ) that obtains, y (t) is reconstructed, obtain:

Because the power supply signal that uses is a pseudo-random code, i.e. pulse signal, therefore

Because the correlativity of undesired signal and pseudo-random code is very little, so can be approximated to:

When n was enough big, useful signal with the ratio of the enlargement factor of noise was: (2 like this ⁿ-1)/and 2n, thus enough signal-to-noise characteristic obtained by changing n, thus obtain more to approach the impulse response of true value.Thereby when n is enough big, can with

Divided by (2 ⁿ-1) the approximate impulse response G (T) that obtains.

The described parameter that obtains the geophysics meaning is: the impulse response of the pumping signal that sends being done the pumping signal that auto-correlation processing obtains sending, do the impulse response that cross correlation process obtains received signal to received signal, impulse response to the pumping signal that sends is done fast fourier transform, obtain the real part and the imaginary part of signal under each frequency, thereby obtain the amplitude-frequency characteristic curve and the phase frequency characteristic curve of the pumping signal that sends respectively; In like manner, impulse response is to received signal done fast fourier transform, obtains the amplitude-frequency characteristic curve and the phase frequency characteristic curve of received signal; Deduct the phase frequency characteristic curve respective tones point value of the pumping signal of transmission with each value of frequency point of the phase frequency characteristic curve of received signal, obtain the absolute phase values φ of each frequency _sWith each value of frequency point of amplitude-frequency characteristic curve of received signal value, multiply by electrode coefficient K again and promptly obtain apparent resistivity value ρ divided by the corresponding frequency of amplitude-frequency characteristic curve of the pumping signal that sends _s=K * U/I.Mathematical processes of the present invention verifies that through the MATLAB software emulation used mathematical formulae is public in early stage.

The pumping signal minimum frequency that transmitter sends in the resistivity prospecting method of the present invention is 2 ^-10Hz, maximum frequency are 2 ²⁰Hz.

According to resistivity prospecting method of the present invention,, if use 2～20 pseudorandom m sequence codes, the origin polynomial expression can produce by following table, according to known theory, the origin root of a polynomial can have a variety of according to the n difference, now several characteristic origin polynomial expression is listed as follows:

M sequence figure place (n)	Part origin polynomial expression
		2	f(x)＝x 2+x 1+1
3	f(x)＝x 3+x 2+1
		4	f(x)＝x 4+x 3+1
5	f(x)＝x 5+x 3+1
		6	f(x)＝x 6+x 5+1

7	f(x)＝x 7+x 6+1
		8	f(x)＝x 8+x 6+x 5+x 4+1
9	f(x)＝x 9+x 5+1
		10	f(x)＝x 10+x 7+1
11	f(x)＝x 11+x 9+1
		12	f(x)＝x 12+x 11+x 8+x 6+1
13	f(x)＝x 13+x 12+x 10+x 9+1
		14	f(x)＝x 14+x 13+x 8+x 4+1
15	f(x)＝x 15+x 14+1
		16	f(x)＝x 16+x 15+x 13+x 4+1
17	f(x)＝x 17+x 14+1
		18	f(x)＝x 18+x 11+1
19	f(x)＝x 19+x 18+x 17+x 14+1
		20	f(x)＝x 20+x 17+1

Chip-spaced T is the minimum interval of transmitter power supply, can pass through computer settings, and from 0.1s to 4s, transmitter sends the cycle with (2 ⁿ-1) * T is the cycle.

As shown in Figure 1, be that example describes transmitter power supply feature in detail with 4 bit codes, use the origin polynomial expression to be

F (x)=x ⁴+ x ³+ 1, original state is " 000001 ", and the chip-spaced time is T,

T=500ms, minimum frequency=1/ (16*T)=0.125

Maximum frequency=1/T=2

Transmitter sends the pumping signal of the pseudo-random code of this m sequence four sign indicating number, receiver receives can select for use behind the measuring-signal MATLAB software to carry out measuring-signal after convolutional calculation obtains reconstruct, by fast fourier transform the pumping signal that sends is done the impulse response that auto-correlation calculates the pumping signal of transmission again, do the impulse response that cross-correlation calculation obtains received signal to received signal, impulse response to the pumping signal that sends is done fast fourier transform, obtain the real part and the imaginary part of signal under each frequency, can obtain the amplitude-frequency characteristic curve and the phase frequency characteristic curve of the pumping signal that sends respectively; In like manner, impulse response is to received signal done fast fourier transform, obtains the amplitude-frequency characteristic curve and the phase frequency characteristic curve of received signal.

Deduct the phase frequency characteristic curve respective tones point value of the pumping signal of transmission with each value of frequency point of the phase frequency characteristic curve of received signal, obtain the absolute phase values φ of each frequency _sWith each value of frequency point of amplitude-frequency characteristic curve of received signal value, multiply by electrode coefficient K again and promptly obtain apparent resistivity value ρ divided by the corresponding frequency of amplitude-frequency characteristic curve of the pumping signal that sends _s=K * U/I.

The measurement mechanism that is used for the resistivity prospecting method of the present invention includes transmitter and receiver.

As shown in Figure 2, described transmitter comprises: transmitter scale programmable logic device 1 links to each other with the input and output of transmitter control computer 0, the output of transmitter scale programmable logic device 1 links to each other with logical sequence generator 3, the output of described logical sequence generator 3 connects driving and holding circuit 6, the output of described driving and holding circuit 6 is connected to electrodes of A B8, the output of described driving and holding circuit 6 is also successively by reaching the input end that is connected to transmitter scale programmable logic device 1 from sampling processing circuit 4 from sampling filter circuit 7, described transmitter scale programmable logic device 1 also connects transmitter clock synchronizing circuit 2, and described driving and holding circuit 6 are by direct supply 5 power supplies;

As shown in Figure 3; described receiver comprises: will be from the input signal 9 of receiving electrode successively by exporting to receiver control computer 14 behind filtering and holding circuit 10, amplification and AD sample circuit 11 and the receiver scale programmable logic device 12, and described receiver scale programmable logic device 12 also connects receiver clock synchronizing circuit 13.

Between the Receiver And Transmitter of the present invention by GPS synchronously or by the line locking circuit design, synchronously after between the two clocking error can control and reach 200ns.

As shown in Figure 4, described transmitter clock synchronizing circuit 2 comprises: the external gps antenna 20 of Chuan Jie transmitter, transmitter GPS module 21, transmitter buffer circuit 23 and the synchronous output line 22 of transmitter successively, wherein, the output terminal of described transmitter buffer circuit 23 and transmitter scale programmable logic device 1.

Because the synchronous and synchronous dual mode of GPS of measurement mechanism Support Line that is used for the resistivity prospecting method of the present invention, so when using the GPS method of synchronization, use external GPS module 20 input signals as synchronizing signal, transmitter output synchronizing signal is to synchronous output line when using the line locking mode.

As shown in Figure 5; described logical sequence generator 3 comprises: control signal level shifting circuit 25 links to each other with the output terminal of transmitter scale programmable logic device 1; the output terminal of described control signal level shifting circuit 25 connects isolates and positive and negative inverting circuit 26, and the output of described isolation and positive and negative inverting circuit 26 connects driving and holding circuit 6.

As shown in Figure 6, described driving and holding circuit 6 comprise: first sample resistance 32, over-current detection 31, buffer circuit 30, high-voltage switch drive circuit 34, High Speed I GBT circuit 33, second sample resistance 35, wherein, described first sample resistance 32 is serially connected in the positive voltage terminal of direct supply 5, the two ends of sample resistance 32 are connected to the input end of over-current detection circuit 31, the output terminal of described over-current detection circuit 31 is connected to the input end of buffer circuit 30, and the output terminal of described buffer circuit 30 is received the circuit input end of transmitter scale programmable logic device 1; The input end of described high-voltage switch drive circuit 34 connects the circuit output end of logical sequence generator 3, the output terminal of high-voltage switch drive circuit 34 is received the control end of High Speed I GBT circuit 33, and the output terminal of High Speed I GBT circuit 33 is connected on the electrodes of A B8 after by second sample resistance 35; Two of second sample resistance 35 terminates to the input end from sampling filter circuit 7.

As shown in Figure 7, described amplifying circuit 42, low pass and notch filter circuit 41 and the AD sample circuit 40 that is connected in series successively that comprise from sampling processing circuit 4, wherein, the input end of described amplifying circuit 42 connects the output terminal from sampling filter circuit 7, and the output terminal of described AD sample circuit 40 connects the input end of transmitter scale programmable logic device 1.

As shown in Figure 8, described receiver clock synchronizing circuit 13 comprises the external gps antenna 50 of receiver, receiver GPS module 51, clock synchronization line 52, receiver buffer circuit 53, the external gps antenna 50 of described receiver is connected to the input end of receiver GPS module 51, the output terminal of described receiver GPS module 51 is connected to one tunnel input of receiver buffer circuit 53, described clock synchronization line 52 is connected to another road input of receiver buffer circuit 53, and the output signal of described receiver buffer circuit 53 is connected on the receiver scale programmable logic device 12.

Claims (7)

1. resistivity prospecting method, it is characterized in that, comprise by transmitter and have the current waveform of pseudo-random code characteristic as pumping signal to underground transmission, receiver receives the voltage signal that is produced by pumping signal, obtain impulse response by mathematics manipulation, obtain the amplitude-frequency characteristic curve and the phase frequency characteristic curve of corresponding frequencies section again by fast fourier transform, and obtain range value, the phase value of each frequency, and obtain apparent resistivity and phase parameter with geophysics meaning;

It is as follows that wherein said mathematics manipulation obtains in the impulse response process of mathematics manipulation:

$y\left(t\right)={\∫}_{-\∞}^{+\∞}G(t-\mathrm{\σ})*u\left(\mathrm{\σ}\right)*\mathrm{d\σ}+e\left(t\right)$

Wherein: y (t) is the measuring-signal that instrument obtains, i.e. measuring-signal between the receiving electrode MN, and G (t-σ) is an impulse response, and u (σ) is that power supply signal is a pseudo random signal, and e (t) is a undesired signal;

Measuring-signal convolution power supply signal u (σ) with instrument obtains is reconstructed y (t), obtains:

$\tilde{y}\left(t\right)={\∫}_{-\∞}^{+\∞}y(t-\mathrm{\σ})*u\left(\mathrm{\σ}\right)*\mathrm{d\σ}$

$={\∫}_{-\∞}^{+\∞}G(t-\mathrm{\σ}){\∫}_{-\∞}^{+\∞}u(\mathrm{\σ}-\mathrm{\τ})*u\left(\mathrm{\τ}\right)*\mathrm{d\τ}*\mathrm{d\σ}+{\∫}_{-\∞}^{+\∞}e(t-\mathrm{\σ})*u\left(\mathrm{\σ}\right)*\mathrm{d\σ}$

Because the power supply signal that uses is a pseudo-random code, i.e. pulse signal, therefore

$\tilde{y}\left(t\right)=(2^n-1)G\left(T\right)+{\∫}_{-\∞}^{+\∞}e(t-\mathrm{\σ})*u\left(\mathrm{\σ}\right)*\mathrm{d\σ}$

Because the correlativity of undesired signal and pseudo-random code is very little, so can be approximated to:

$\tilde{y}\left(t\right)=(2^n-1)G\left(t\right)+2n*\tilde{e}$

It is the undesired signal of convolution; When n was enough big, useful signal with the ratio of the enlargement factor of noise was: (2 ⁿ-1)/and 2n, thus enough signal-to-noise characteristic obtained by changing n, thus obtain more to approach the impulse response of true value;

The process that wherein obtains apparent resistivity with geophysics meaning and phase parameter is as follows: the impulse response of the pumping signal that sends being done the pumping signal that auto-correlation processing obtains sending, do the impulse response that cross correlation process obtains received signal to received signal, impulse response to the pumping signal that sends is done fast fourier transform, obtain the real part and the imaginary part of signal under each frequency, thereby obtain the amplitude-frequency characteristic curve and the phase frequency characteristic curve of the pumping signal that sends respectively; In like manner, impulse response is to received signal done fast fourier transform, obtains the amplitude-frequency characteristic curve and the phase frequency characteristic curve of received signal; Deduct the phase frequency characteristic curve respective tones point value of the pumping signal of transmission with each value of frequency point of the phase frequency characteristic curve of received signal, obtain the absolute phase values φ of each frequency _sWith each value of frequency point of amplitude-frequency characteristic curve of received signal value, multiply by electrode coefficient K again and promptly obtain apparent resistivity value ρ divided by the corresponding frequency of amplitude-frequency characteristic curve of the pumping signal that sends _s=K * U/I.

2. resistivity prospecting method according to claim 1, it is characterized in that, described transmission has that the code length of pseudo-random code of current waveform of pseudo-random code characteristic is adjustable, the origin polynomial expression can be selected, bit rate is adjustable, start-phase is adjustable, the pumping signal that is sent is from first phase, the current waveform that will have pseudo-random characteristics according to code length, origin polynomial expression, bit rate and the start-phase set sends successively, with 2 ⁿ-1 is the cycle, n be one greater than 0 less than 20 integer.

3. resistivity prospecting method according to claim 1 is characterized in that, the current waveform minimum frequency of the pumping signal that transmitter sends is 2 ^-10Hz, maximum frequency are 2 ²⁰Hz.

4. measurement mechanism that is used for the described resistivity prospecting method of claim 1, include transmitter and receiver, it is characterized in that, described transmitter comprises: transmitter scale programmable logic device (1) links to each other with the input and output of transmitter control computer (0), the output of transmitter scale programmable logic device (1) links to each other with logical sequence generator (3), the output of described logical sequence generator (3) connects driving and holding circuit (6), the output of described driving and holding circuit (6) is connected to electrodes of A B (8), the output of described driving and holding circuit (6) is also successively by reaching the input end that is connected to transmitter scale programmable logic device (1) from sampling processing circuit (4) from sampling filter circuit (7), described transmitter scale programmable logic device (1) also connects transmitter clock synchronizing circuit (2), and described driving and holding circuit (6) are powered by direct supply (5);

Described receiver comprises: will be from the input signal (9) of receiving electrode successively by filtering and holding circuit (10), amplification and AD sample circuit (11), export to receiver control computer (14) after the data processing after receiver scale programmable logic device (12) is sampled to AD, described receiver scale programmable logic device (12) also connects receiver clock synchronizing circuit (13);

Wherein said driving and holding circuit (6) comprising: first sample resistance (32), over-current detection circuit (31), buffer circuit (30), high-voltage switch drive circuit (34), High Speed I GBT circuit (33), second sample resistance (35), wherein, described first sample resistance (32) is serially connected in the positive voltage terminal of direct supply (5), the two ends of first sample resistance (32) are connected to the input end of over-current detection circuit (31), the output terminal of described over-current detection circuit (31) is connected to the input end of buffer circuit (30), and the output terminal of described buffer circuit (30) is received the circuit input end of transmitter scale programmable logic device (1); The input end of described high-voltage switch drive circuit (34) connects the circuit output end of logical sequence generator (3), the output terminal of high-voltage switch drive circuit (34) is received the control end of High Speed I GBT circuit (33), and the output terminal of High Speed I GBT circuit (33) is connected on the electrodes of A B (8) after by second sample resistance (35); Two input ends that terminate to from sampling filter circuit (7) of second sample resistance (35);

Described amplifying circuit (42), low pass and notch filter circuit (41) and the AD sample circuit (40) that is connected in series successively that comprise from sampling processing circuit (4), wherein, the input end of described amplifying circuit (42) connects the output terminal from sampling filter circuit (7), and the output terminal of described AD sample circuit (40) connects the input end of transmitter scale programmable logic device (1).

5. the measurement mechanism that is used for the resistivity prospecting method according to claim 4, it is characterized in that, described transmitter clock synchronizing circuit (2) comprising: the external gps antenna of Chuan Jie transmitter (20), transmitter GPS module (21), transmitter buffer circuit (23) and the synchronous output line of transmitter (22) successively, wherein the output terminal of transmitter buffer circuit (23) connects transmitter scale programmable logic device (1).

6. the measurement mechanism that is used for the resistivity prospecting method according to claim 4; it is characterized in that; described logical sequence generator (3) comprising: control signal level shifting circuit (25) links to each other with the output terminal of transmitter scale programmable logic device (1); the output terminal of described control signal level shifting circuit (25) connects isolates and positive and negative inverting circuit (26), and the output of described isolation and positive and negative inverting circuit (26) connects driving and holding circuit (6).

7. the measurement mechanism that is used for the resistivity prospecting method according to claim 4, it is characterized in that, described receiver clock synchronizing circuit (13) comprises the external gps antenna of receiver (50), receiver GPS module (51), clock synchronization line (52), receiver buffer circuit (53), the external gps antenna of described receiver (50) is connected to the input end of receiver GPS module (51), the output terminal of described receiver GPS module (51) is connected to one tunnel input of receiver buffer circuit (53), described clock synchronization line (52) is connected to another road input of receiver buffer circuit (53), and the output signal of described receiver buffer circuit (53) is connected on the receiver scale programmable logic device (12).

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