CN103454688A

CN103454688A - Multi-channel electrical logging device of three-dimensional electrical resistivity imaging system

Info

Publication number: CN103454688A
Application number: CN2013104107516A
Authority: CN
Inventors: 邓居智; 刘庆成; 徐哈宁; 曾正军; 汤洪志; 黎正根; 肖慧; 龚育龄
Original assignee: East China Institute of Technology
Current assignee: East China Institute of Technology
Priority date: 2013-09-11
Filing date: 2013-09-11
Publication date: 2013-12-18

Abstract

The invention provides a multi-channel electrical logging device of a three-dimensional electrical resistivity imaging system. Two 8-channel 24-bit high speed and high precision analog-digital converters are used as the core of an analog circuit part for data acquisition, each channel is provided with an independent front end conditioning circuit which is formed by a sampling holder, a low pass filter, a programmable amplifier, an electric potential translation circuit and a voltage reference circuit. CortexM3 is used as the core of a digital part, data transmission is conducted through two SPI bus control and an analog part, a GPIO interface controls the high precision analog-digital converters to be connected with the front end conditioning circuits to form a feedback circuit to improve measuring precision, and multiple electrical logging devices can be mutually connected through a CAN bus. The 16-path parallel acquisition mode is adopted, the signal of each path is provided with the independent front end conditioning circuit, the high-speed data processing function of LPC 1788 is utilized, data are preprocessed by the adoption of a digital filtering algorithm, and data reliability of the electrical logging device and the whole system performance are improved.

Description

Three-dimensional resistivity imaging system hyperchannel electric probe device

Technical field

The invention belongs to the geophysical exploration technology field, relate to a kind of three-dimensional resistivity imaging system hyperchannel electric probe device.

Background technology

The research work of resistivity prospecting starts from earlier 1800s, and along with the reach of science with look for the needs in ore deposit, the theoretical and instrument of resistivity prospecting becomes better and approaching perfection day by day.Enter the beginning of this century, along with the application of large scale integrated circuit and the further raising of computing velocity, resistivity prospecting has started to the three-dimensional development, and high-density electric instrument developed into for the 4th generation from the first generation.

3 D resistivity acquisition hardware system is comprised of master control system, electric probe device, intelligent electrode system, electric power system, polycore cable, transmission cable (bus) etc.Electric probe device is as the important component part of hardware system, need to meet following some main task: (1) signal condition, the electric probe device input signal is comprised of external noise, system noise and useful signal stack, by signal sampling hold circuit, passive low-pass filter circuit, main discharge able to programme road, the front end input circuit is processed; (2) signal conversion processes, be converted to digital quantity by the analog quantity of modulate circuit output, and input processor carries out digital filtering, and filtered signal is transferred to main frame; (3) show and control, each electric probe device independently has liquid crystal display and 4 * 4 QWERTY keyboard for realizing human-computer interaction function, realizes that parameter input, data show and device is controlled function.(4) synchronizing function, complete in time synchronous of a plurality of electric probe devices by GPS, realizes running simultaneously data acquisition and processing.

Summary of the invention

Purpose of the present invention just is to provide the three-dimensional resistivity imaging system hyperchannel electric probe device of hardware system to the requirement of data electric probe device in a kind of energy capable of meeting requirements on three-dimensional resistivity imaging system.

Three-dimensional resistivity imaging system hyperchannel electric probe device of the present invention, comprise simulation part, preposition modulate circuit, numerical portion, and simulation part divides and comprises two 24 bit A/D converters (U49, U50), each AD converter acquisition process 8 road input signal; Preposition modulate circuit is comprised of sampling hold circuit (U1～U16), low-pass filter circuit (U17～U32), pga circuit (U33～U48), current potential translation circuit and voltage reference circuit, input signal, at first by sampling hold circuit (U1～U16), guarantees the stability of AD converted input signal; The double T low-pass filter network that low-pass filter circuit (U17～U32) resistance and electric capacity form, it has the filtering high-frequency interferencing signal, eliminates the effect of noise, and allows the direct-flow input signal of measuring pass through smoothly; Pga circuit and AD driving circuit (U33～U48), the enlargement factor basis of gain-programmed amplifier power-up period A/D converter output voltage is for the first time set by main control computer, the signal amplitude that makes to be input to A/D converter always, between A/D converter half range and full scale, guarantees the precision of A/D conversion; Numerical portion is Cortex M3-LPC1788(U51) control collection and the transmission of data by spi bus, realize the data transmission between a plurality of electric measuring systems and main frame by the CAN bus, control human-computer interaction interface and 12 figure place weighted-voltage D/A converter DAC8562(U52 by the GPIO mouth) form feedback control circuit with front-end circuit, by the state conversion of 485 total line traffic control intelligent electrodes, by serial ports, control the GPS synchronizing function.

Device is preferably: embedded microprocessor Cortex M3-LPC1788, analog to digital converter DAC8562, digital to analog converter ADS1278, programmable gain amplifier PGA204, fiducial chip REF525, amplifier INA128, CAN buses isolator CTM8251.

Three-dimensional resistivity imaging system hyperchannel electric probe device of the present invention, for picking rate and the stability that improves electric probe device, adopt 16 road parallel acquisition modes, every road signal has independently front end modulate circuit, utilize the high-speed data processing capacity of LPC1788, adopt digital filtering algorithm to carry out pre-service to data, improved data reliability and the whole system performance of electric probe device.

The accompanying drawing explanation

Fig. 1 is configuration diagram of the present invention;

Fig. 2 is simulation part parallel circuit schematic diagram in the embodiment of the present invention;

Fig. 3 is numerical portion circuit diagram in the embodiment of the present invention.

Specific embodiments

By reference to the accompanying drawings example 1 is described further:

In Fig. 1, double T low-pass filter network low-pass filter circuit (U17～U32), pga circuit and AD driving circuit (U33～U48) that input signal forms by sampling hold circuit (U1～U16), resistance and electric capacity, input a/d converter, data are controlled the collection of data and are transferred to the numerical portion core by spi bus is Cortex M3-LPC1788(U51).Numerical portion is realized the data transmission between a plurality of electric measuring systems and main frame by the CAN bus, by the GPIO mouth, controls human-computer interaction interface (serial port liquid crystal screen and 4 * 4 keyboards) and 12 figure place weighted-voltage D/A converter DAC8562(U52) form feedback control circuit with front-end circuit.

The simulation part separation structure as shown in Figure 2.Take INA128(U1～U16) be the amplifier part of the core of analog signal processing sampling holder, cable input plug is connected as input with No. 3 pins 2.According to the formula gain amplifier

Figure 2013104107516100002DEST_PATH_IMAGE002

, 1,8 pins are hung empty enlargement factor and are set to 1, signal are not amplified, and purpose is to make the input impedance of its acquisition system enough large, makes the current potential numerical value measured more approach the actual value in field.In order to prevent that data from aliased distortion occurring after gathering and reduce external noise, need simulation low-pass filter, digital filter and both combinations, the double T low-pass filter network that the analog filter of the present invention's design is comprised of resistance and electric capacity.

In field resistivity measurement process, the voltage signal that potential electrode receives is large 1V～5V, little have a few μ V, and the ADS1278(U49 of rear class, U50) benchmark of 24 A/D converters of high precision is 5V, its conversion range is (2.5V～+ 2.5V), if the input signal of a few μ V is not exaggerated, to change its error of voltage of a few μ V be also very large for U49, U50 so, PGA204(U33～U48) there are the adjustable gains such as 1,10,100,1000.Gain is by microprocessor LPC1788(U51) 11, No. 12 pins of control PGA204 are regulated, and INA128(U1～U16) inner input protection can harmlessly bear the analog input up to ± 40V.The enlargement factor of gain-programmed amplifier is set by main control computer according to power-up period A/D converter output voltage for the first time, and the signal amplitude that makes to be input to A/D converter always, between A/D converter half range and full scale, guarantees the precision of A/D conversion.

ADS1278(U49, U50) allow balance aspect speed, precision, power consumption to select a kind of from following 4 kinds of mode of operations, and model selection is by MODE[1: 0] input state of (33,34) pin determines, seven kinds of data output formats are arranged, and data output format comprises interface protocol, data output and Data Position.It is FORMAT[2:0 that data output format is controlled pin] (30,31, No. 32 pins), this example is by FORMAT[2:0] be set to 001, interface protocol is that SPI, output format are that TDM, Data Position are selected to fix.

The numerical portion structural drawing as shown in Figure 3.U49, U50 data acquisition commencing signal are by its 11 pin (/SYNC) input, when/SYNC input end is low level, U49 ,U50 eight roads stop sampling, inner digital filter resets, subsequently/SYNC input end is for becoming high level, U49 ,U50 eight roads start synchronized sampling, utilize LPC1788(U51) 26, No. 52 pins to U49, U50 /SYNC end controlled.28,29,30,31,54,56,60, No. 66 pins and U50, the U49 of U51 carry out data transmission.

U51 is connected with 1～9,17,18, No. 19 pin of digital to analog converter U52 as the numeral input of U52 by 83～No. 95 pins of GPIO mouth, and No. 13 pins of simulation output of U52 are connected and realize FEEDBACK CONTROL with No. 5 reference pin of U1.

33,35,37,39,41,43,45,47 8 GPIO mouths of U51 are connected with 4 * 4 standard waterproff keyboards, the functions such as the parameter input of controlling electric probe device of being connected with the serial port liquid crystal screen by 18, No. 20 pins, data display and processing, data storage, GPS control.U51 by 1 road CAN bus controller realize with a plurality of electric probe devices and main frame between communicate by letter.

Claims

1. a three-dimensional resistivity imaging system hyperchannel electric probe device, comprise the simulation part, preposition modulate circuit, numerical portion, it is characterized in that: simulation part divides and comprises two 24 analog to digital converter ADS1278(U49, U50), preposition modulate circuit is by sampling hold circuit (U1～U16), low-pass filter circuit (U17～U32), pga circuit (U33～U48), current potential translation circuit and voltage reference circuit form, numerical portion core Cortex M3-LPC1788(U51) control collection and the transmission of data, human-computer interaction interface, 12 figure place weighted-voltage D/A converter DAC8562(U52) form feedback control circuit with front-end circuit, input signal is by take No. 6 pins inputs of the sampling hold circuit (U1～U16) that INA128 is core, by low-pass filter circuit (U17～U32), the forward amplifying signal is inputted 24 analog to digital converter ADS1278(U49 by No. 11 pin outputs of pga circuit (U33～U48) with parallel mode, U50) 3, 1, 63, 61, 51, 49, 47, No. 45 pins, 16 tunnels are inputted and are connected 24 analog to digital converter ADS1278(U49, U50) 4, 2, 64, 62, 52, 50, 48, No. 46 pins, voltage reference circuit connects 24 analog to digital converter ADS1278(U49, U50) No. 10 pins form the AD driving circuit, after signal is digital quantity by analog-converted, by spi bus, be transferred on the two-way SPI controller of numerical portion core (U51), numerical portion core (U51) is transferred to digital to analog converter DAC8562(U52 by digital signal with parallel mode by 12 GPIO mouths after signal is processed) 1～9,17, No. 18 pin, and be connected to form feedback control circuit with No. 5 pins of sampling hold circuit (U1～U16), numerical portion core (U51) is connected with the TFT liquid crystal display by 1 road serial ports, by 8 road GPIO mouths, with 4 * 4 waterproff keyboards, is connected, and by serial ports, connects GPS.

2. three-dimensional resistivity imaging system hyperchannel electric probe device according to claim 1, it is characterized in that: 16 road input signals have independently front end modulate circuit, adopt the differential mode mode to input, and have realized 16 road signal parallel collections.