CN104459803B - The natural field source electromagnetic measurement device of intelligent long period and its application method - Google Patents

Abstract

An intelligent long-period natural field source electromagnetic measurement device and its application method are provided. The device includes a sensor component (1), an analog-to-digital conversion module (2), an intelligent control module (3), and a clock module (4 ), the storage module (5), the power conversion module (6), the lead-acid battery (7), the communication module (8) and the portable computer (9). The field source electromagnetic signal is accurately measured. The frequency range of the device is 20S～n*10000S (n is a natural number between 1 and 10), and the measurement amplitude range is n×1uV～n×100mV (n is a natural number between 1 and 10. ), the measurement dynamic range is up to 120dB, the system noise is less than 1μVrms, the operating temperature range is -20℃～+70℃, and the power consumption is <4W. The device has the characteristics of high reliability, multi-channel, large dynamic range, strong anti-interference ability, low power consumption, large storage medium capacity, and intelligence.

Description

Intelligent long-period natural field source electromagnetic measuring device and its application method

Technical field:

The present invention relates to the field of geophysical exploration, in particular to a material exploration device and detection method, that is, an intelligent long-period natural field source electromagnetic measurement device and its use method, which is suitable for long-period natural field source electromagnetic signals on the ground Measurements are performed to study the resistivity distribution of subsurface media and to probe the three-dimensional conductivity structure of the crust-upper mantle.

Background technique:

At present, the major developed countries in the world regard the "crustal exploration" plan as their own scientific and technological development strategy to uncover the mystery of continental crustal evolution, effectively search for resources, mitigate natural disasters, protect the environment, and achieve sustainable development. For example, the "LithoProbe" and "EarthScope" that have been implemented or are being implemented in European and American countries have provided a series of new theories and new perspectives for the formation and evolution of the crust, the theory of ore deposit genesis, and resource prospect evaluation. Technical Support.

In order to change my country's current dilemma of energy and mineral resource shortages, and to further enhance the national disaster early warning capability, my country began to implement the "Deep Detection Technology and Experimental Research (SinoProbe)" special project in 2008, as a cultivation of the "Crustal Exploration Project". research plan. Among them, the "Continental Electromagnetic Parameter 'Standard Network' Experimental Research (SinoProbe-01)" project aims to solve the key technical issues of constructing continental-scale, array-type (Array) magnetotelluric sounding "standard point" observation network. and provide demonstration results; lay the foundation for the final establishment of a "standard" model of the three-dimensional conductive structure of the lithosphere in mainland China; this project will provide an important basis for revealing the characteristics of China's tectonic features and lithosphere structure The theory of tectonics has great significance.

To implement the detection and research of the conductive structure of the crust and upper mantle, it is necessary to collect electromagnetic signals from natural field sources with a period of tens of thousands of seconds. Its basic principle: when the electromagnetic signal of natural field source propagates in the underground medium, due to electromagnetic induction, the observation value of the ground electromagnetic field contains the information of the resistivity distribution of the underground medium, so by observing the mutually orthogonal electromagnetic field components on the ground, we can understand the underground Electrical structure of media at different depths. Electromagnetic field signals with different periods have different skin depths. The longer the period of the magnetic field, the greater the detection depth. When the collected natural field source electromagnetic signal has a period of tens of thousands of seconds, the detection depth can reach the upper mantle.

At present, only the LIMS produced in Canada, the NIMS produced in the United States and the LEMI-417 produced in Ukraine are specially used for the observation of long-period natural field source electromagnetic signals. Among them, the three-component magnetic sensors in LIMS and NIMS use certain military special materials, so the United States and other countries have always banned exports to my country; the natural field source electromagnetic signal measuring instruments used in China in recent years can only be LEMI imported from Ukraine -417, but the price of this type of instrument has been rising, and there are some defects in the technical performance of the instrument, such as when the GPS signal cannot be received or the GPS device fails, the time recorded by the system is confused; no recent reference is provided , Remote reference measurement function; the system can only query and analyze the data collected by one instrument, and cannot flexibly query and intuitively analyze the data files collected by multiple instruments within a time period.

The completed "Continental Electromagnetic Parameter 'Standard Network' Experimental Research (SinoProbe-01)" project has well solved a series of key technical issues and problems in building an array type (Array) magnetotelluric sounding "standard point" observation network. The specific implementation plan and demonstration results are provided; this has laid a good technical foundation for the great engineering task of detecting the three-dimensional conductive structure of the Chinese mainland's crust-upper mantle in the "Crustal Exploration Project" to be launched in my country. Obviously, to complete this huge engineering task, it is necessary to complete a large number of high-quality natural field source electromagnetic signal observations with a period of tens of thousands of seconds across the country, and it is undoubtedly necessary to use a large number of long-period natural field source electromagnetic signal observation devices.

Therefore, it is very necessary to develop a long-period natural field source electromagnetic signal observation device with my country's independent intellectual property rights, excellent technical performance, and high intelligence. It is of great significance to greatly improve the research level of the instrument support conditions in the field of crust-mantle conductivity structure research.

Invention content:

In order to overcome the above-mentioned problems faced by the long-period natural field source electromagnetic signal measurement on the ground, the present invention proposes an intelligent long-period natural field source electromagnetic measurement device and its application method.

According to the first aspect of the present invention, the device for intelligent long-period natural field source electromagnetic measurement includes a sensor component, an analog-to-digital conversion module, an intelligent control module, a clock module, a storage module, a power conversion module, a lead-acid battery, a communication module, Portable computer, described sensor part is made up of long-period electric field sensor, three-component fluxgate sensor and temperature sensor; The output terminal of described long-period electric field sensor, three-component fluxgate sensor and temperature sensor is connected with the voltage of analog-to-digital conversion module The signal input terminal is connected; the output terminal of the analog-to-digital conversion module is connected with the general I/O port of the intelligent control module; the clock pairing module is composed of a GPS module, a GPS antenna, a real-time clock circuit and a rechargeable battery; the The input and output signals of the GPS module and the real-time clock circuit are connected to the general I/O port of the intelligent control module; the storage module is composed of a storage interface, a CF card and a card reader; the I/O bus of the storage interface is connected to the intelligent The bus of the control module is connected, and the conversion result of the analog-digital conversion module is stored in the CF card through the storage interface; the CF card transmits the conversion result of the analog-digital conversion module to the portable computer through the card reader; the communication module has a wireless There are two ways of communication and wired communication; the intelligent control module performs information interaction with the portable computer through the communication module; the power conversion module converts the power provided by the lead-acid battery into the power required by each component, and provides power for each component.

According to the second aspect of the present invention, the measurement method using the above-mentioned intelligent long-period natural field source electromagnetic measurement device includes the following steps:

1) Select a location with relatively little interference in the area to be observed to deploy stations, select a point as the central measuring point, dig a 50CM deep pit and bury a long-period electric field sensor, and connect it to the long-period natural field source electromagnetic signal measuring device through a wire At the "ground" signal end, with the help of the forest compass, dig a cylindrical pit with a diameter of 30 cm and a depth of 50 cm at 50 meters in the north, south, west, and east directions of the central measuring point, and respectively bury two long-period electric fields Sensors, as electric field signals Ex1+, Ex2+, Ex1-, Ex2-, Ey1+, Ey2+, Ey1-, Ey2-, are connected to the analog-to-digital conversion module 2 through a 60-meter wire, and another 50CM (length) × 50CM (width) )×100CM (height) cuboid pit to place the three-component fluxgate sensor and connect it to the analog-to-digital conversion module through a dedicated cable.

2) Set up the GPS antenna, connect the lead-acid storage battery to power on the device of the present invention, complete the initialization of each module after the device of the present invention is powered on, and detect whether each part is normal.

3) The portable computer data interaction software accesses and controls the intelligent control module through the communication module, so that the intelligent control module obtains the GPS information provided by the GPS module, and writes the acquired time into the real-time clock circuit to ensure that multiple long-period natural field source electromagnetic The time synchronization of the signal measurement device is convenient for remote reference observation, and its synchronization accuracy is 10 ^-8 s/s; since the clock source of the real-time clock circuit will not be lost when the power is turned off, if the GPS signal in the observation area is low Poor or GPS components are damaged, the data interaction software of the portable computer commands the intelligent control module through the communication module to adopt the time information provided by the real-time clock circuit.

4) The data interaction software of the portable computer controls the intelligent control module through the communication module, so that the device of the present invention starts trial mining of data, and the data of trial mining is stored in the CF card on the one hand, and stored in the portable computer through the communication module on the one hand, and the data interaction The software decodes, restores and displays the data in a dynamic graphic, guides the user to adjust the position of the three-component fluxgate sensor so that the three directions point to true north, true east, and true downward, and helps users analyze the quality of data collection .

5) The data interaction software of the portable computer controls the intelligent control module through the communication module, so that the trial mining ends. After the trial mining, the intelligent control module calculates better acquisition parameters such as gain according to the trial mining data, and feeds back to the user.

6) The user comprehensively evaluates and sets reasonable acquisition parameters according to the analysis of the test mining data and the acquisition parameters calculated by the intelligent control module, and the data interaction software of the portable computer feeds back to the intelligent control module through the communication module to control the device of the present invention Start to formally collect data. On the one hand, the collected data is stored in the CF card, and on the other hand, it is stored in the portable computer through the communication module. After the instrument starts to collect data, the portable computer can be separated from the device of the present invention at any time, so that the device of the present invention can work independently.

7) During the data collection process, the intelligent control module can display its working status through the LED indicator light, and send the collected data and status information through the communication module, and the portable computer can be connected with the device of the present invention at any time to obtain the above information.

8) after the given data collection time arrives, the portable computer is connected with the device of the present invention, and the data interaction software of the portable computer sends a stop command to the intelligent control module through the communication module, so that the collection work ends; Power supply, read the data in the CF card into the portable computer through the card reader, and obtain the resistivity distribution and three-dimensional conductivity structure of the underground medium through data processing and inversion software.

Using the intelligent long-period natural field source electromagnetic measurement device and its application method of the present invention, the long-period natural field source electromagnetic signals can be measured on the ground, so as to facilitate the study of the resistivity distribution of the underground medium and the detection of the crust-upper mantle Three-dimensional conductive structures. This intelligent long-period natural field source electromagnetic measurement device can obtain natural field source electromagnetic signals (n is a natural number between 1 and 10), and has the characteristics of good usability, high reliability, and low power consumption.

Description of drawings:

Fig. 1 is the structural representation of the device for the electromagnetic measurement of intelligent long-period natural field sources according to the present invention;

Fig. 2 is the operating schematic diagram of the device for the electromagnetic measurement of intelligent long-period natural field sources according to the present invention;

Fig. 3 is the functional block diagram of the analog-to-digital conversion module in the device for intelligent long-period natural field source electromagnetic measurement of the present invention;

4 is a schematic diagram of the storage interface circuit principle of the storage module in the device for intelligent long-period natural field source electromagnetic measurement of the present invention;

5 is a schematic diagram of the circuit principle of the intelligent control module in the device for intelligent long-period natural field source electromagnetic measurement of the present invention;

Fig. 6 is a structural block diagram of the power conversion module in the device for intelligent long-period natural field source electromagnetic measurement of the present invention;

Fig. 7 is a structural block diagram of the communication module based on the wired communication mode in the device for intelligent long-period natural field source electromagnetic measurement of the present invention;

Fig. 8 is a structural block diagram of a communication module based on wireless communication in the device for intelligent long-period natural field source electromagnetic measurement of the present invention.

Specific implementation method:

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Below in conjunction with accompanying drawing, structural principle and working principle of the present invention are specifically described:

Referring to Fig. 1 and Fig. 2, Fig. 1 is a structural schematic diagram of the device for intelligent long-period natural field source electromagnetic measurement of the present invention, and Fig. 2 is a schematic diagram of the operation of the device for intelligent long-period natural field source electromagnetic measurement of the present invention. The device for intelligent long-period natural field source electromagnetic measurement of the present invention includes a sensor component 1, an analog-to-digital conversion module 2, an intelligent control module 3, a clock module 4, a storage module 5, a power conversion module 6, a lead-acid battery 7, and a communication module 8. Portable computer 9, said sensor part 1 is made up of long-period electric field sensor 11, three-component fluxgate sensor 12 and temperature sensor 13; said long-period electric field sensor 11, three-component fluxgate sensor 12 and temperature sensor 13 The output end of the analog-to-digital conversion module 2 is connected to the voltage signal input end; the output end of the analog-to-digital conversion module 2 is connected to the general I/O port of the intelligent control module 3; the clock pair module 4 is connected by a GPS antenna 41, GPS module 42, real-time clock circuit 43 and rechargeable battery 44 are formed; The input and output signals of described GPS module 42 and real-time clock circuit 43 are connected with the general I/O port of intelligent control module 3; Described storage module 5 is made up of Composed of a storage interface 51, a CF card 52 and a card reader 53; the I/O bus of the storage interface 5 is connected to the bus of the intelligent control module 3, and the conversion result of the analog-to-digital conversion module 2 is stored in the CF through the storage interface 51. Card 52; the CF card 52 transmits the conversion result of the analog-to-digital conversion module 2 to the portable computer 9 through the card reader 53; the communication module 8 has two modes of wireless communication and wired communication; the intelligent control module 3 passes through the communication module 8 and the portable computer 9 for information interaction; the power conversion module 6 converts the power provided by the lead-acid battery 7 into the power required by each component, and provides power for each component.

Referring to Fig. 1 and Fig. 2 again, the sensing part 1 comprises: a total of 9 long-period electric field sensors 11, one of which is buried in the center measuring point, connected to the "long-period natural field source electromagnetic signal measuring device" of the long-period natural field source electromagnetic signal measuring device through a wire In addition, two are respectively buried at 50 meters in the north, south, west and east directions of the central measuring point, and are connected to the analog-to-digital conversion module 2 with a 60-meter electrode line to receive natural The electric field signal in the field source is converted and output as an analog signal corresponding to the change of the electric field, and two sets of horizontal and orthogonal electric fields (Ex, Ey) are obtained, which improves the fault tolerance of the system. The long-period electric field sensor adopts a self-developed solid non-polar chemical electrode; three-component fluxgate sensor 12, which is connected with the analog-to-digital conversion module 2 by a special cable, receives the magnetic field signal in the natural field source and converts and outputs an analog signal corresponding to the change of the magnetic field. During trial mining, adjust Its position is such that the three directions point to the true north, the true east, and the true downward respectively, and three mutually orthogonal magnetic field signals (Hx, Hy, Hz) are obtained. The fluxgate sensor is Mag-03MSESL70, and its measurement range is ±7000NT , the accuracy is 0.006NT, the weight is 160g, and the size is 32mm×32mm×166mm; the temperature sensor 13 measures the temperature change of the three-component fluxgate sensor and is used to correct the magnetic field measurement signal. The temperature current source AD590 has a wide temperature range (-55°C to 150°C), high precision, and strong anti-interference ability, and the current flowing through the device is proportional to the thermodynamic temperature, which is easy to correct.

Referring to FIG. 3 , FIG. 3 is a functional block diagram of the analog-to-digital conversion module 2 of the device of the present invention. The analog-to-digital conversion module 2 adopts a new generation of chipset scheme launched by Cirrus Logic. Each chip package consists of 4 pieces of CS3301 operational amplifier 23, 2 pieces of CS5372 modulator 24, and 1 piece of CS5376 filter 25. This system adopts Two chip sets; the first chip set converts the electric field analog signals Ex1, Ey1, Ex2, and Ey2 acquired by the long-period electric field sensor 11 into digital signals, and the second chip set converts the three-component fluxgate sensor 12 to obtain The voltage signals Hx, Hy, Hz corresponding to the magnetic field signal and the voltage signal Tb corresponding to the temperature of the three-component fluxgate sensor acquired by the temperature sensor 13 are converted into digital signals. In order to ensure the synchronization of the two CS5376 filters 25, the two CS5376 filters 25 are externally connected to the same high-precision crystal oscillator 26, and are triggered by the same pin of the intelligent control module 3 to work. The CS3301 operational amplifier 23 in this package solution has seven gain modes: 1×, 2×, 4×, 8×, 16×, 32×, and 64×. The maximum signal measured at 1× gain is ±2.5V, 64 The maximum signal measured under × gain is ±39mV, and the accuracy measured under 64× gain is less than 100nV, so that the measurement dynamic range can reach 120dB. Since the output value of the three-component fluxgate sensor reaches ±10V, the output of the three-component fluxgate sensor can be adjusted to the allowable range of the CS3301 operational amplifier 23 through the preamplifier circuit, but this reduces the measurement accuracy, in order to increase the magnetic field The measurement accuracy is high, the system adopts feedback control, and three pieces of DAC8565 devices 27 of digital/analog converter are added in the circuit, so that the output is offset with the constant part of Hx, Hy, Hz respectively, that is, only the variable part is amplified, Make CS3301 operational amplifier work in 64× gain in the second package plan.

Referring to FIG. 2 again, the clock module 4 shown in the figure is composed of a GPS antenna 41 , a GPS module 42 , a real-time clock circuit 43 , and a rechargeable battery 44 . The GPS information that GPS antenna 41 obtains is handed over to intelligent control module 3 by GPS module 42, and the time of acquisition is written into real-time clock circuit 43, and real-time clock circuit 43 is powered by rechargeable battery 44, and real-time clock circuit 43 is in the situation of power failure The lower clock source will not be lost either. If the GPS signal in the observation area is poor or the GPS components are damaged, the device of the present invention uses the time information provided by the real-time clock circuit 43 . The clock module 2 ensures the time synchronization of multiple long-period natural field source electromagnetic signal measurement devices, which is convenient for remote reference observation, and its synchronization accuracy is 10 ^-8 s/s;

Referring to Fig. 4, Fig. 4 is the schematic diagram of the storage interface 51 circuit principle of the device storage module 5 of the present invention. This device adopts a CF card with low power consumption, strong shock resistance and excellent pluggability as the storage medium, so the storage interface needs to be designed , the present invention adopts the storage interface 51 generated by the bus provided by the intelligent control module 3 to be connected to the CF card. The data in is read to portable computer 9 by card reader 53, and CF card has adopted FAT16 as file system format.

Referring to FIG. 7, FIG. 7 is a structural block diagram of a communication module based on wired communication. The communication module based on wired communication adopts MAX3232 chip 81 to convert the TTL level to RS232 level, and directly connects with the serial port of the portable computer, so that the intelligent control module 3 and the portable computer 9 can exchange information.

Referring to FIG. 8, FIG. 8 is a structural block diagram of a communication module based on a wireless communication mode. The communication module based on wireless communication mode is composed of MAX3232 chip 81, wireless transceiver module A82 and wireless transceiver module B83. The information sent by the intelligent control module 3 is delivered to the wireless transceiver module A82 through the MAX3232 chip 81, and sent out by the wireless transceiver module A82. After the wireless transceiver module B83 receives the information, it is delivered to the portable computer 9 through the serial port of the portable computer 9. vice versa. The wireless transceiver module adopts a high-power module whose signal is controlled by JN5121. The wireless communication method enables users to operate in nearby tents and cars under severe weather conditions.

Referring to FIG. 5 , FIG. 5 is a schematic diagram of the circuit principle of the intelligent control module 3 . The main control device of intelligent control module 3 adopts 8-bit CMOS processor Atmega128. Atmega128 has high performance and low power consumption. It adopts advanced RISC structure and single-cycle instruction execution time. Contradiction between power consumption and processing speed, and rich internal resources (with 128KB FLASH internal memory, 4KB EEPROM and 4KB SRAM data storage space, including 53 programmable multi-function I/O ports, 2 8-bit timer counters , 2 16-bit timing counters, SPI, I2C, USART, 8-way ADC, etc.), with JTAG interface, easy to download and debug.

Atmega128's PB0～PB7, PD4～PD5, PE2～PE5, PG3～PG4, PF1, a total of 17 I/O ports are connected to the analog-to-digital conversion module 2, PB4 selects the CS5376 of the first set of chips, and PD4 selects the second The CS5376 and PD5 of the two chip sets plan select the auxiliary DAC8565, PE4 and PE5 of the second chip set plan to check whether the two chip sets are ready, and PB0 and PB5~PB6 control the data collection of the two chip sets. Synchronization, PB1~PB3 download configuration parameters for two chip sets, PE2~PE3 get the conversion result of the first chip set, PG3~PG4 get the conversion result of the second chip set, PF1 resets DAC8565 by software .

TxD1, TxD1 of Atmega128 and INT7 altogether 3 I/O ports are connected with the GPS module 42 of clock module 4, TxD1, TxD1 provide the serial communication work mode for both, INT7 receives the second interruption that GPS module 42 provides (in when the GPS signal is active). The model selected by the GPS module is iTrax02.

The SCL, SDA and INT6 of Atmega128 have 3 I/O ports in total and the real-time clock circuit 43 of the clock module 4 are connected, SCL and SDA provide the I2C communication working mode, and INT6 receives the interrupt provided by the real-time clock circuit 43 (when the GPS signal is invalid Time). The real-time clock circuit adopts PCF8563.

PA0～PA7, PC0～PC4, ALE, RD, WR, PD6 and PD7 of Atmega128 have a total of 18 I/O ports connected to storage module 5, PA0～PA7 provide data lines for storage module 5, PC0～PC7 are storage modules 5 provides address lines, RD and WR provide read and write control signals for storage module 5, PD7 provides software reset control signals for storage module 5, and PD6 provides feedback signals for detecting whether CF card 52 exists for storage module 5.

TxD0, TxD0 two I/ O ports of Atmega128 are connected with communication module 8, and the communication mode between the two is serial communication.

PF2 of Atmega128 is externally connected to LED to indicate the working status of the device; PF3 is externally connected to buttons to provide a shortcut for the intelligent control module 3 to quickly stop collection; PF0 obtains the power of the lead-acid battery 7 and sends an alarm when it is insufficient.

Referring to FIG. 6 , FIG. 6 is a structural block diagram of the power conversion module 6 . The device of the present invention adopts the lead-acid storage battery 7 to supply power for the whole system. Since the device of the present invention adopts many components and parts, and the working voltages of different components or parts are different, the power conversion module 6 adopts a large number of components with high conversion efficiency and low noise. Low DC/DC (direct current to direct current power supply), specifically includes: lead-acid battery 7 to +12V DC/DC component 61, provides operating voltage for three-component fluxgate sensor 12, the lead-acid battery 7 that the present invention selects The DC/DC component 61 that turns +12V is LT1962; the DC/DC component 62 that the lead-acid battery 7 turns +5V supplies power for the DAC device (DAC8565) 27, and the lead-acid battery that the present invention selects turns 7 +5V DC The /DC component 62 is LT1962; the DC/DC component 64 of the lead-acid storage battery 7 turns +3.3V provides the working voltage for the intelligent control module 3 and the storage module 5, and the lead-acid battery 7 turns +3.3V used in the present invention The DC/DC component 64 is LM2674; the DC/DC component 63 of lead-acid battery 7 to +4V provides intermediate conversion voltage for the system, and the DC/DC component 63 of lead-acid battery 7 to +4V selected in the present invention is LM2674; +4V to +2.5V DC/DC component 65, providing operating voltage for the operational amplifier (CS3301) 23, the +4V to +2.5V DC/DC component 65 selected by the present invention is LT1962; +4V to The DC/DC component 66 of -3V provides an intermediate conversion voltage for the system. The DC/DC component 66 of +4V to -3V selected by the present invention is MAX764; the DC/DC component 67 of -3V to -2.5V, To provide operating voltage for the operational amplifier (CS3301) 23, the -3V to -2.5V DC/DC component 67 selected by the present invention is LT1964; the -3V to -12V DC/DC component 68 is a three-component fluxgate The sensor 12 provides the working voltage, and the -3V to -12V DC/DC component 68 selected in the present invention is LT1964.

Referring to Fig. 2 again, the method for using the device for intelligent long-period natural field source electromagnetic measurement comprises the following steps:

1) Select a place with relatively little interference in the area to be observed to deploy stations, select one point as the central measuring point, dig a 50CM deep pit and bury a long-period electric field sensor 11, and connect it to the long-period natural field source electromagnetic signal measuring device through a wire With the help of the forest compass, dig a cylindrical pit with a diameter of 30 cm and a depth of 50 cm at 50 meters in the north, south, west and east directions of the central measuring point, and lay two long pits for each. The periodic electric field sensor 11, Ex1+, Ex2+, Ex1-, Ex2-, Ey1+, Ey2+, Ey1-, Ey2- as the electric field signal, is connected to the analog-to-digital conversion module 2 through a 60-meter wire, and another 50CM (long) × A cuboid pit of 50CM (width)×100CM (height) is used to place the three-component fluxgate sensor 13, and is connected to the analog-to-digital conversion module 2 through a dedicated cable.

2) Set up the GPS antenna 41, connect the lead-acid battery 7 to power on the device of the present invention, complete the initialization of each module after the device of the present invention is powered on, and detect whether each component is normal.

3) The portable computer 9 data interaction software accesses and controls the intelligent control module 3 through the communication module 8, so that the intelligent control module 3 obtains the GPS information provided by the GPS module 42, and writes the time obtained into the real-time clock circuit 43 to ensure multiple The time synchronization of the station's long-period natural field source electromagnetic signal measurement device is convenient for remote reference observations, and its synchronization accuracy is 10 ^-8 s/s; since the clock source of the RTC will not be lost when the power is turned off, if the observation If the GPS signal in the area is poor or the GPS components are damaged, the data interaction software of the portable computer 9 commands the intelligent control module 3 to adopt the time information provided by the real-time clock circuit 43 through the communication module 8 .

4) The data interactive software of portable computer 9 is controlled intelligent control module 3 by communication module 8, makes the device of the present invention start trial mining data, and the data of trial mining is stored in CF card 52 on the one hand, is stored in by communication module 8 on the one hand. The portable computer 9, the data interaction software decodes and restores the data, and displays it dynamically and graphically, instructs the user to adjust the position of the three-component fluxgate sensor 12 so that its three directions point to true north, true east, and true downward respectively, and Help users analyze the quality of data collection.

5) the data interactive software of portable computer 9 is controlled intelligent control module 3 by communication module 8, and trial mining is ended, and intelligent control module 3 calculates acquisition parameters such as better gain according to the data of trial mining after trial mining, Feedback to users.

6) The user comprehensively evaluates and sets reasonable acquisition parameters according to the analysis of the trial mining data and the acquisition parameters calculated by the intelligent control module 3, and the data interaction software of the portable computer 9 feeds back to the intelligent control module 3 through the communication module 3, The device of the present invention is controlled to start collecting data formally, and the collected data is stored in the CF card 52 on the one hand, and stored in the portable computer 9 through the communication module 8 on the one hand. After the instrument starts to collect data, the portable computer 9 can be separated from the device of the present invention at any time to make the device of the present invention work independently.

7) In the data acquisition process, the intelligent control module 3 can display its working status through the LED indicator light, and send the collected data and status information through the communication module 8, and the portable computer 9 can be connected with the device of the present invention at any time to obtain the above information .

8) after the given data collection time arrives, the portable computer 9 is connected with the device of the present invention, and the data interaction software of the portable computer 9 sends a stop command to the intelligent control module 3 through the communication module 8, so that the collection work is finished; The power supply provided by the acid battery 7 reads the data in the CF card 52 into the portable computer 9 through the card reader 53, and through data processing and inversion software, the resistivity distribution and three-dimensional conductivity structure of the underground medium are obtained.

The device of the present invention and the method of use thereof are technical achievements obtained by the inventor after long-term research and great effort. Specifically, the intelligent long-period natural field source electromagnetic measurement device of the present invention solves the following technical difficulties:

1) How to ensure that the circuit system can collect data for a long time

The instrument works in the field, generally powered by lead-acid batteries, and due to the detection and research of the crust-mantle conductive structure, it is necessary to collect natural field source electromagnetic signals with a frequency range of 20S～n×10000S (n is between 1 and 10 natural number), so the system needs to work continuously for about 10 days, or even 3 to 4 weeks, at each measuring point. Therefore, the system must have the characteristics of low power consumption on the one hand, and on the other hand, it must have strong reliability and stability. Carry out fault self-test and restart after the system crashes.

How to Improve the Anti-interference Capability and Signal-to-Noise Ratio of Circuit System

The electromagnetic signal of natural field sources is generally lower than n×100mV (n is a natural number between 1 and 10), the signal is extremely weak and the amplitude is small, and with the development of the national economy, the electromagnetic noise becomes more and more serious, and the quality of magnetotelluric data is declining. , especially the decline in the quality of electric field data observation is more obvious. The instrument should have high precision and low noise characteristics, and can detect weak useful signals. It is required that the system noise of the instrument should be less than 1uVpp, and the measurement dynamic range should reach 120dB.

2) How to realize multi-channel and intelligent acquisition of electromagnetic signals

The signals measured by the system include three mutually orthogonal magnetic signals Hx, Hy, Hz, electric signals Ex, Ey perpendicular to each other on the horizontal plane, and the working temperature Tb of the instrument. Compared with the observation quality of magnetic field and electric field data, the decline trend of electric field data observation quality is more obvious. In order to improve the reliability and fault tolerance of the measurement, a high-performance long-period electric field sensor is selected, and the electric field signals Ex and Ey are measured in two channels, respectively. They are Ex1, Ex2 and Ey1, Ey2; the magnetic field sensor is a three-component fluxgate sensor, and the temperature sensor is AD590 with strong anti-interference ability and high precision. The above 8 measurement signals should be synchronized during collection. All operations of the instrument should be intelligent, and automatically collect, store, check whether data is lost, and perform interpolation.

3) How to realize the far reference technology

Since the electromagnetic field signal is a weak signal, when the instrument is working, each measurement signal is susceptible to various noise interference, and it may be the same noise interference. When working with multiple instruments, if the distance between the instruments is selected properly, they can avoid the influence of the same noise and ensure that the noise is not correlated, and because the magnetic field is less affected by the unevenness of the ground surface, it is possible to ensure that the signal between the magnetic field There is correlation. At this time, if the magnetic field signal collected by another instrument is used instead of the magnetic field signal collected by this instrument, the influence of irrelevant noise can be eliminated. This technology is called the observation technology with remote reference method, and it is the most advanced electromagnetic sounding data observation technology at present. This technique requires the instruments to be clocked in the same way. The GPS clock alignment method can provide guarantee for the remote reference measurement of multiple instruments. However, when the GPS signal is weak or the GPS component fails, the time record of the instrument is prone to errors; for this reason, this instrument has designed an emergency real-time clock source RTC (Real-Time Clock) with a rechargeable battery. Perform a clock calibration at a place with a strong GPS signal to obtain the international standard time and save it in the RTC. Since the clock source of the RTC will not be lost when the power of the instrument is powered off, when the system is working at the measuring point, when there is no GPS signal When using this high-precision clock source to obtain the time, it can successfully solve the problems of the instrument not working or time recording error when there is no GPS signal.

4) The basis for selecting data storage media and how to store and manage the collected data

Since the instrument takes a long time to collect data in the field, it generally measures continuously for 10 days at each measurement point, sometimes for 3-4 weeks, or even longer, so a large-capacity data storage medium is required, and the storage medium should be shock-resistant , small size, light weight, low power consumption, good pluggability and other characteristics, integrated various storage media, chose the CF card. Since the collected data needs to be read by a card reader and checked, played back, and processed on a PC, the file format of the CF card should be consistent with the file system of the PC, that is, create a file in the CF card with the Windows operating system. system, so that the file system can effectively manage the data in the CF card. At present, the file systems widely used in PCs include FAT (divided into FAT12, FAT16, FAT32) and NTFS. Among them, the FAT (File Allocation Table) file system was produced in the early 1980s and is MS-DOS, WindowsXP The file system supported by the operating system, because most of the long-period magnetotelluric data processing systems are based on DOS and WindowsXP, so this system uses FAT16.

5) How to prevent users from having to work on site in harsh environments

The instrument works in the field, and often encounters severe weather such as heavy snow, strong wind, and cold. In order to prevent the staff from working under harsh conditions such as cold wind, the communication between the portable computer and the instrument adopts two methods: wired communication (serial communication) ) and wireless communication, the former is suitable for on-site operation under normal weather, and the latter is suitable for operation in nearby tents and cars under severe weather conditions. In addition, when the instrument is working, if the working voltage of the lead-acid battery is insufficient, the storage space of the CF card is insufficient, etc., the alarm information can also be transmitted to the staff watching the station in time through wireless operation.

6) Development of host computer data interaction software

The data collected by the acquisition part is uploaded to the portable computer through serial communication or wireless communication, and the data playback software of the host computer performs preprocessing, time series graphical playback and browsing, etc.

The intelligent long-period natural field source electromagnetic measurement device of the present invention has achieved the following technical indicators:

Frequency range: 20S～n*10000S (n is a natural number between 1 and 10);

The measurement circuit includes 8 data acquisition channels, which respectively collect four horizontally orthogonal electric fields (Ex1, Ey1, Ex2, Ey2), three horizontally and vertically orthogonal magnetic fields (Hx, Hy, Hz), one temperature signal;

Measurement amplitude: n×1uV～n×100mV (n is a natural number between 1 and 10);

Adopt high-speed and high-precision 24-bit analog-to-digital conversion;

Using RISC-based low-power 8-bit CMOS processor Atmega128 microcontroller as the control chip to realize intelligent automatic operation, recording and storage;

Measuring dynamic range: 120dB;

System noise is less than 1μVrms;

Storage space 2GB;

"GPS + high-precision temperature compensation crystal oscillator" mode synchronization error is less than 20ns;

The clock stability is better than 10-8s/s;

The self-developed solid non-polarized electric field electrode is used as a long-period electric field sensor;

Using three-component fluxgate sensor;

It can measure the observation position, internal temperature and other parameters of the instrument;

Power consumption of the whole instrument: <4W;

The working temperature range of the instrument is -20℃～+70℃.

The above steps have described the device and method proposed by the present invention in detail. Those skilled in the art can understand that without departing from the spirit and scope of the present invention defined by the appended claims, many changes can be made in the form and details. kind of modification. Therefore, all the various modifications made with reference to the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims (9)

1. A device for intelligent long-period natural field source electromagnetic measurement, which includes a sensor component (1), an analog-to-digital conversion module (2), an intelligent control module (3), a clock module (4), a storage module (5 ), power conversion module (6), lead-acid storage battery (7), communication module (8), portable computer (9), it is characterized in that: Described sensor component (1) is made up of long-period electric field sensor (11), three-component fluxgate sensor (12) and temperature sensor (13); Described long-period electric field sensor (11), three-component fluxgate sensor ( 12) and the output end of the temperature sensor (13) is connected with the voltage signal input end of the analog-digital conversion module (2); the output end of the analog-digital conversion module (2) is connected with the general I/O of the intelligent control module (3) O mouth is connected; Described clock module (4) is made up of GPS antenna (41), GPS module (42), real-time clock circuit (43) and rechargeable battery (44); Described GPS module (42) and real-time clock The input and output signals of the circuit (43) are connected with the general I/O port of the intelligent control module (3); the storage module (5) is composed of a storage interface (51), a CF card (52) and a card reader (53) Composition; the I/O bus of the storage interface ( 51 ) is connected with the bus of the intelligent control module (3), and the conversion result of the analog-to-digital conversion module (2) is stored to the CF card (52) through the storage interface (51) ); the CF card (52) transmits the conversion result of the analog-to-digital conversion module (2) to the portable computer (9) by the card reader (53); the communication module (8) has two kinds of wireless communication and wired communication mode; the intelligent control module (3) performs information interaction with the portable computer (9) through the communication module (8); the power conversion module (6) converts the power provided by the lead-acid battery (7) into the power required by each component Provides power to the various components. 2. The device as claimed in claim 1, wherein said sensor components comprise: 9 long-period electric field sensors (11), wherein one long-period electric field sensor is embedded in the central measuring point, connected to the long-period natural field by wires The "ground" signal end of the source electromagnetic signal measurement device; in addition, two long-period electric field sensors are respectively buried at 50 meters in the north, south, west and east directions of the central measuring point, and a 60-meter electrode line is used to connect the north A total of 8 long-period electric field sensors buried in the four directions of , south, west and east are connected with the analog-to-digital conversion module (2) to receive the electric field signal in the natural field source and convert and output the analog signal corresponding to the change of the electric field. The periodic electric field sensor uses solid non-polarized electrodes; A special cable is used to connect the three-component fluxgate sensor (12) with the analog-to-digital conversion module (2), receive the magnetic field signal in the natural field source and convert and output an analog signal corresponding to the change of the magnetic field, the three-component fluxgate sensor The model is Mag-03MSESL70; The temperature sensor (13) measures the temperature change of the three-component fluxgate sensor and is used for correcting the magnetic field measurement signal. A monolithic integrated two-terminal temperature-sensing current source AD590 is selected. 3. The device according to claim 1, wherein the analog-to-digital conversion module adopts a chip-on-chip solution launched by Cirrus Logic. 4. The apparatus of claim 1, wherein the clock-setting module comprises: The GPS antenna (41) obtains the GPS information provided by the communication satellite, and gives it to the GPS module (42) by a dedicated signal line; GPS module (42), is connected with the serial port 2 of intelligent control module (3), gives the GPS information that GPS antenna (41) obtains to intelligent control module (3), analyzes the position of measuring point by intelligent control module (3) Information and collection time information, the GPS module adopts the model 42iTrax02; The real-time clock circuit (43) is connected with the I2C port of the intelligent control module (3), and the intelligent control module (3) writes the time obtained into the real-time clock circuit (43), and the real-time clock circuit (43) is powered by a rechargeable battery (44) Power supply, the real-time clock circuit (43) model is PCF8563; The rechargeable battery (44) supplies power for the real-time clock circuit, so that the clock source signal is not lost when the real-time clock circuit is powered off. 5. The apparatus of claim 1, wherein the storage module comprises: The storage interface (51) is connected with the bus of the intelligent control module (3), converted into a signal line suitable for the work of the CF card, and connected with the CF card, and receives the acquisition parameters and acquisition data transmitted by the intelligent control module (3) , store to CF card; The CF card (52) is connected with the storage interface (51), and stores the acquisition parameters and the acquisition data transmitted by the intelligent control module (3). The CF card has adopted the general FAT16 file system format of the computer operating system; The card reader (53) transmits the storage data of the CF card (52) to the portable computer (9) in a file format, which is convenient for the portable computer (9) to process. 6. The apparatus of claim 1, wherein the power conversion module comprises: The power conversion module uses a lead-acid battery to supply power to the device for measuring the long-period natural field source electromagnetic signal. The power conversion module uses a DC-to-DC power supply LT1962, LT1964, MAX764 or LM2674. 7. The device according to claim 1, wherein the model of the intelligent control module (3) is Atmega128. 8. The apparatus of claim 1, wherein the communication module comprises: The communication module based on the wired communication mode adopts MAX3232 chip (81) to convert the TTL level into RS232 level, and directly connects with the serial port of the portable computer (9), so that the intelligent control module (3) can communicate with the portable computer (9) Information exchange; The communication module based on wireless communication mode is composed of MAX3232 chip (81), wireless transceiver module A (82) and wireless transceiver module B (83). The transceiver module A (82) is sent out by the wireless transceiver module A (82), and after the wireless transceiver module B (83) receives the information, it is delivered to the portable computer (9) through the serial port of the portable computer (9). 9. use the measuring method of any one of claim 1-8 measuring device, comprise the steps: 1) Select a location with relatively little interference in the area to be observed for station deployment, select a point as the central measuring point, dig a 50CM deep pit and bury a long-period electric field sensor (11), and connect it to an intelligent long-period natural field source electromagnetic sensor (11) through a wire. The "ground" signal end of the measuring device; with the help of the forest compass, dig a cylindrical pit with a diameter of 30 cm and a depth of 50 cm at 50 meters in the north, south, west, and east directions of the central measuring point. A long-period electric field sensor (11), respectively as the electric field signal Ex1+, Ex2+, Ex1-, Ex2-, Ey1+, Ey2+, Ey1-, Ey2-, is connected to the analog-to-digital conversion module (2) by a wire of 60 meters, in addition Dig a cuboid pit with a length of 50CM, a width of 50CM and a height of 100CM, to place the three-component fluxgate sensor (13), and connect to the analog-to-digital conversion module (2) by a dedicated cable; 2) Set up the GPS antenna (41), connect the lead-acid battery (7) to power on the device for intelligent long-period natural field source electromagnetic measurement, and complete each module after the device for intelligent long-period natural field source electromagnetic measurement is powered on Initialization, to detect whether each component of the device that constitutes the intelligent long-period natural field source electromagnetic measurement is normal; 3) The data interaction software of the portable computer (9) accesses and controls the intelligent control module (3) through the communication module (8), so that the intelligent control module (3) obtains the GPS information provided by the GPS module (42), and writes the time into real-time Clock circuit (43), to ensure the time synchronization of multiple intelligent long-period natural field source electromagnetic measurement devices, and the synchronization accuracy is 10-8s/s; 4) The data interaction software of the portable computer (9) controls the intelligent control module (3) through the communication module (8), so that the device for intelligent long-period natural field source electromagnetic measurement starts trial mining data, and the trial mining data on the one hand Stored in the CF card (52), on the one hand, stored in the portable computer (9) through the communication module (8), the data interaction software decodes and restores the data, and dynamically displays it graphically to guide the user to adjust the three-component fluxgate sensor ( 12) so that the three directions point to true north, true east, and direct downward, and help users analyze the quality of data collection; 5) The data interaction software of the portable computer (9) controls the intelligent control module (3) through the communication module (8), so that the trial mining ends. After the trial mining, the intelligent control module (3) calculates according to the data of the trial mining Collect parameters and give feedback to users; 6) According to the analysis of test mining data and the collection parameters calculated by the intelligent control module (3), the user comprehensively evaluates and sets reasonable collection parameters, and the data interaction software of the portable computer (9) feeds back through the communication module (3) For the intelligent control module (3), the device for controlling the intelligent long-period natural field source electromagnetic measurement begins to formally collect data. The collected data is stored in the CF card (52) on the one hand, and stored in the portable computer through the communication module (8) on the other hand. (9); after the device for intelligent long-period natural field source electromagnetic measurement starts to collect data, the portable computer (9) can be separated from the device for intelligent long-period natural field source electromagnetic measurement at any time, so that the intelligent long-period natural field source The device for electromagnetic measurement works alone; 7) During the data collection process, the intelligent control module (3) can display its working status through the LED indicator light, and send the collected data and status information to the outside through the communication module (8), and the portable computer (9) can communicate with the intelligent Device connection for electromagnetic measurement of long-period natural field sources; 8) After the given data collection time arrives, the portable computer (9) is connected with the device for intelligent long-period natural field source electromagnetic measurement, and the data interaction software of the portable computer (9) is sent through the communication module (8) to stop Command to the intelligent control module (3), so that the collection work ends; the power supply provided by the lead-acid storage battery (7) is closed, and the data in the CF card (52) is read into the portable computer (9) by the card reader (53). Data processing and inversion software to obtain the resistivity distribution and three-dimensional conductivity structure of the underground medium.