CN203465429U - Pseudo-random code electrical instrument - Google Patents

Abstract

The utility model discloses a pseudo-random code electrical instrument. The pseudo-random code electrical instrument includes a transmitter and a receiver. The transmitter comprises a FPGA processing module, a constant current source module and an ADC data acquisition module. The FPGA processing module comprises a master control CPU and an FPGA connected with the master control CPU and used for time sequence control. The constant current source module comprises a driving circuit, a constant current power source and a standard resistor, wherein the driving circuit, the constant current power source and the standard resistor are connected in sequence. The ADC data acquisition module comprises an operational amplifier, a differential amplifier, an ADC, a two-port RAM and a DSP and further comprises a CPLD used for algorithm integration, wherein the operational amplifier, the differential amplifier, the ADC, the two-port RAM and the DSP are connected in sequence, and the CPLD is connected with the ADC, the two-port RAM and the DSP. The FPGA is connected with the CPLD through a synchronous interface, and the DSP is connected with the RAM and connected to a PC upper computer through a USB controller. The receiver comprises an SMA connector, an operational amplifier, a differential amplifier, an ADC, an FPGA and a DSP and further comprises a master control CPU connected with the FPGA and the DSP, wherein the SMA connector, the operational amplifier, the differential amplifier, the ADC, the FPGA and the DSP are connected in sequence, and the DSP is connected to the PC upper computer through a USB MCU module. The pseudo-random code electrical instrument is high in anti-interference performance and exploration efficiency and can adapt to complicated environments.

Description

Pseudo-random code electrical prospecting apparatus

Technical field

The utility model relates to geologic prospecting equipment, is specifically related to a kind of pseudo-random code electrical prospecting apparatus.

Background technology

EMP method is one of most widely used and effective method during ore prospecting and engineering and environment are reconnoitred.But for a long time, these class methods are subject to the puzzlement of the following aspects: first, be that its antijamming capability is lower, particularly carry out the work in industrial district or city, be subject to various electrical Interference.Secondly, conventional frequency-domian electromagnetic sounding, need to be in certain band limits, and frequency is observed one by one, and production efficiency is lower.The 3rd, during some electromagnetic exploration method is observed in the wild, need to arrange and to reach several wires to tens kilometers, this not only makes its observation device heavy and further reduce production efficiency, and makes it be difficult in city or carry out the work in the area of other landform, atural object complicated condition.

Middle and later periods in 20th century, method that system identification theory has developed a kind of " system identification of pseudo-random binary input signal ".Pseudo random binary signal sequence (PRBS) is that amplitude is constant, and the periodic square wave spike train of width random variation.It can be produced by specialized equipment, also can be produced simply by digital machine.The ultimate principle of above-mentioned " system identification " is, utilizes pseudo random binary signal source for example, to system to be identified (, geologic prospecting object---the earth) input pseudo random signal (electric current), observes the output signal (voltage) of this system simultaneously.According to the cross correlation function of output signal and input signal, just can identify this system.

The calculating of cross correlation function is a numerical filter calculating process, therefore utilizes cross correlation function recognition system to have very strong antijamming capability.In the situation that suitably selecting pseudo random binary signal sequence (PRBS) correlation parameter, cross correlation function approaches the impulse response of system very much, thus, is easy to calculate to obtain the frequency response of system, and do not need to carry out frequency measurement one by one consuming time, thereby greatly improve observed efficiency.In addition, adopt PRBS as signal source, be also easy to realize the radio contact between input (power supply) device and output (measurement) device, thereby make observation device lighting, not only can enhance productivity, and can expand its range of application.Visible, the EMP method of research and utilization PRBS, is expected to solve three subject matters that perplex current EMP method really.

Utility model content

Technical problem to be solved in the utility model is that existing electromagnetic survey equipment antijamming capability is low, and exploration efficiency is low, is difficult to adapt to the problem of complex environment.

In order to solve the problems of the technologies described above, the technical scheme that the utility model adopts is to provide a kind of pseudo-random code electrical prospecting apparatus, comprises transmitter and receiver: transmitter comprises FPGA processing module, constant-current source module and adc data acquisition module: FPGA processing module comprises master cpu and the FPGA for sequential control being attached thereto; Constant-current source module comprises driving circuit, stabilized current supply and the measuring resistance connecting successively; Adc data acquisition module comprises operational amplifier, differential amplifier, ADC, dual port RAM, the DSP connecting successively, also comprise for the integrated CPLD of algorithm, described CPLD is connected with ADC, dual port RAM and DSP respectively, described FPGA is connected with CPLD by sync cap, described DSP is connected with RAM, and is connected on PC host computer by USB controller; Receiver comprises sub-miniature A connector, operational amplifier, differential amplifier, ADC, FPGA and the DSP connecting successively, also comprises the master cpu being connected with DSP with FPGA respectively, and DSP is connected on PC host computer by USB MCU module; FPGA is field programmable gate array, and ADC is A/D converter, and dual port RAM is first in first out buffer memory, and DSP is digital signal processor, and CPLD is CPLD, and USB MCU is the special-purpose monolithic processor of USB communication.

In above-mentioned pseudo-random code electrical prospecting apparatus, on described FPGA processing module and adc data acquisition module, be also provided with power module, reset circuit and clock frequency synthesizer.

In above-mentioned pseudo-random code electrical prospecting apparatus, on the master cpu of described transmitter and receiver, be also connected with respectively the GPS global positioning system display screen of unifying.

In above-mentioned pseudo-random code electrical prospecting apparatus, on described receiver, be also provided with power module, reset circuit, debug circuit and clock frequency synthesizer.

In above-mentioned pseudo-random code electrical prospecting apparatus, the DSP of described receiver is provided with for storing the SRAM of its data that are disposed.

The pseudo-random code electrical prospecting apparatus antijamming capability that the utility model provides is strong, and exploration efficiency is high, can adapt to complex environment.

Accompanying drawing explanation

The theory structure schematic diagram of the transmitter of the pseudo-random code electrical prospecting apparatus that Fig. 1 provides for the utility model;

The theory structure schematic diagram of the receiver of the pseudo-random code electrical prospecting apparatus that Fig. 2 provides for the utility model;

The pseudo-random code electrical prospecting apparatus that Fig. 3 provides for the utility model is at different time test resistance rate and phase reappearance contrast schematic diagram;

The depth sounding data contrast schematic diagram of the pseudo-random code electrical prospecting apparatus Yu321Lao geologic prospecting party that Fig. 4 provides for the utility model.

Embodiment

Below in conjunction with accompanying drawing, the utility model is described in detail.

As shown in Figure 1 and Figure 2, the pseudo-random code electrical prospecting apparatus that the utility model provides comprises transmitter and receiver.

Transmitter comprises FPGA processing module, constant-current source module and adc data acquisition module.FPGA processing module comprises master cpu and the FPGA for sequential control being attached thereto; Constant-current source module comprises driving circuit, stabilized current supply and the measuring resistance connecting successively; Adc data acquisition module comprises operational amplifier, differential amplifier, ADC, dual port RAM, the DSP connecting successively, also comprise for the integrated CPLD of algorithm, CPLD is connected with ADC, dual port RAM and DSP respectively, FPGA is connected with CPLD by sync cap, DSP is connected with RAM, and is connected on PC host computer by USB controller.On FPGA processing module and adc data acquisition module, be also provided with power module, reset circuit and clock frequency synthesizer.

During transmitter operation, master cpu is controlled FPGA and is produced transmission frequency, via driving circuit and stabilized current supply to emitter, now FPGA produces synchronizing signal simultaneously, pass to closed-loop end CPLD, CPLD transmits ADC collection, transmit and got by the measuring resistance that is connected on transmitting terminal, weak voltage signals in measuring resistance is converted into differential signal by difference amplifier by single-ended signal after via the single-ended amplification of one-level and offers ADC and gather, mass data after collection is coordinated by CPLD, first deposit dual port RAM in, DSP starts to process the data in dual port RAM simultaneously, it is standby that the data of handling well deposit RAM in, while needing, via DSP and USB main control module, reach PC host computer.The logic master cpu of transmitter section is coordinated the cooperation between each module, is responsible for the communication between module, and GUI realizes, the functions such as condition judgment and triggering.

Receiver comprises sub-miniature A connector, operational amplifier, differential amplifier, ADC, FPGA and the DSP connecting successively, also comprise the master cpu being connected with DSP with FPGA respectively, DSP is connected on PC host computer by USB MCU module, and the DSP of receiver is provided with for storing the SRAM of its data that are disposed.On the master cpu of transmitter and receiver, be also connected with respectively the GPS global positioning system display screen of unifying.On receiver, be also provided with power module, reset circuit, debug circuit and clock frequency synthesizer.

Signal is entered by sub-miniature A connector, via single-ended signal being converted into the ADC that differential signal offers by FPGA master control by difference amplifier after the single-ended amplification of one-level, gather, mass data after collection is directly imported DSP into by FPGA and is processed, it is standby that the data of handling well deposit storage SRAM in, while needing, via DSP and USB MCU module, reach PC host computer, the master cpu of receiver is responsible for coordinating the work of FPGA and DSP and is read gps data and GUI realization;

In the foregoing description:

CPU:Central Processing Unit, central processing unit, many acute pyogenic infection of finger tip main control singlechip in native system (as ARM platform);

FPGA:Field-Programmable Gate Array, field programmable gate array, is used for sequential control;

CPLD:Complex Programmable Logic Device, CPLD, is used for algorithm integrated;

GPS:Global Positioning System, GPS, native system middle finger can obtain the communication module of local longitude and latitude and height above sea level via satellite to clock;

RAM:Random Access Memory, random access memory;

DSP:Digital Signal Processor, digital signal processor;

ADC, Analog-to-Digital Converter, A/D converter;

SRAM:Static Random Access Memory, can simply be interpreted as static RAM (SRAM), and function and RAM are basically identical.

The function of above-mentioned module:

GPS module: by the longitude and latitude of Real-time Obtaining present position, show and synchronize and store with sampled data, convenient processing.

FPGA: obtain clock signal by the steady clock source of height, produce specific transmission frequency, through power amplifier access transmitting coil, produce synchronizing signal simultaneously, enable the collection of closed-loop measuring end.

CPLD: initialization AD, and as the data bus between ADC and dual port RAM and DSP, receives transmitting terminal synchronizing signal, enables AD and gathers, and send data to RAM buffer memory and DSP carries out signal processing.

ADC: continually varying simulating signal is converted to discrete digital signal, so that the processing of data and storage.

DSP: the signal being quantized by AD is processed and stored, with the communication of USB controller, the data of storage are reached to host computer.

Dual port RAM: or claim FIFO, first in first out buffer memory, because ADC sample rate is higher, bursty data amount is larger, therefore add a high-speed cache between AD and DSP, data are not lost, and DSP has enough processing times.

Store RAM: speed is slow compared with FIFO, be only connected with DSP, for storing processed data, and when PC retaking of a year or grade, data are spread out of.

SRAM: the data that are disposed for storing DSP.

The special-purpose monolithic processor of USB MCU:USB communication.

Principle of work of the present utility model: the current waveform signal by transmitter to underground transmission pseudorandomcode, receiver receives the pseudorandom voltage signal of launching, and obtains large earth respone function by digital signal processing.Digital signal processing is sequentially: first transmitted signal is done to the large earth respone function that auto-correlation processing obtains transmitted signal, do to received signal the large earth respone function that cross correlation process obtains receiving signal, respectively the large earth respone function of transmitted signal and reception signal is done to fast fourier transform, obtain real part and the imaginary part of signal under each frequency, thereby obtain amplitude-versus-frequency curve and the phase-frequency characteristic curve of transmitted signal and reception signal; Then with the phase-frequency characteristic curve that receives signal, deduct the phase-frequency characteristic curve of transmitted signal, just obtain the absolute phase values of each frequency; With receiving the amplitude-versus-frequency curve of the amplitude-versus-frequency curve of signal divided by transmitted signal, then be multiplied by the electrode coefficient K in physical prospecting, can obtain apparent resistivity.

Pseudo-random code current waveform length is adjustable, origin polynomial expression is optional, bit rate is adjustable, start-phase is adjustable, the signal first phase sending is adjustable, according to code length, origin polynomial expression, bit rate and the initial phase set, the current waveform with pseudo-random characteristics is once sent, with 2 ^n-1for the cycle, n is one and is greater than 0 integer that is less than 20.By adjusting the size of n, can improve measuring accuracy and antijamming capability.

The mathematical procedure of resistivity prospecting image data:

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

Wherein, the signal that y (t) gathers for instrument, i.e. measuring-signal between MN; G (t-σ) is the earth response; U (σ) is power supply signal, i.e. pseudo random signal, and e (t) is undesired signal.

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

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

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

Because the power supply signal using is pseudo-random code, therefore:

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

Due to undesired signal and Pseudo-code Correlation very little, formula can be approximated to:

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

When n is enough large, useful signal with the ratio of the enlargement factor of noise is: (2 ^n-1)/2n, thus by changing n, obtain the signal of enough signal to noise ratio (S/N ratio)s, thus obtain large earth respone function more accurately.

Application case of the present utility model: Tongling Resources Crisis Mines In China

Tongling Dongguashan Copper Mine belongs to the more flourishing mining area of exploitation, and in mining area, house owed by a citizen stands in great numbers, and the exploitation of underground many places is electrically disturbed hugely, and noise amplitudes is 300 millivolts of left and right, and observation voltage is 0.3 millivolt of left and right, signal to noise ratio (S/N ratio) B=-60db left and right, serious interference.Much domestic, international mainstream instrument is all tested in this work, and most instrument different time measuring repeatabilities are very poor, is also difficult to match with four utmost point depth sounding datas the earliest.

The pseudo-random code electrical prospecting apparatus that the utility model provides has been tested resistivity and phase place at different time, and repeatability is very good; The depth sounding data of test result Ye Yu321Lao geologic prospecting party contrasts, and as shown in Figure 3, Figure 4, trend is in full accord.

The utility model is not limited to above-mentioned preferred forms, and anyone should learn the structural change of making under enlightenment of the present utility model, every with the utlity model has identical or close technical scheme, within all falling into protection domain of the present utility model.

Claims (5)

1. pseudo-random code electrical prospecting apparatus, is characterized in that, comprises transmitter and receiver:

Transmitter comprises FPGA processing module, constant-current source module and adc data acquisition module:

FPGA processing module comprises master cpu and the FPGA for sequential control being attached thereto;

Constant-current source module comprises driving circuit, stabilized current supply and the measuring resistance connecting successively;

Adc data acquisition module comprises operational amplifier, differential amplifier, ADC, dual port RAM, the DSP connecting successively, also comprise for the integrated CPLD of algorithm, described CPLD is connected with ADC, dual port RAM and DSP respectively, described FPGA is connected with CPLD by sync cap, described DSP is connected with RAM, and is connected on PC host computer by USB controller;

Receiver comprises sub-miniature A connector, operational amplifier, differential amplifier, ADC, FPGA and the DSP connecting successively, also comprises the master cpu being connected with DSP with FPGA respectively, and DSP is connected on PC host computer by USB MCU module;

FPGA is field programmable gate array, and ADC is A/D converter, and dual port RAM is first in first out buffer memory, and DSP is digital signal processor, and CPLD is CPLD, and USB MCU is the special-purpose monolithic processor of USB communication.

2. pseudo-random code electrical prospecting apparatus as claimed in claim 1, is characterized in that, is also provided with power module, reset circuit and clock frequency synthesizer on described FPGA processing module and adc data acquisition module.

3. pseudo-random code electrical prospecting apparatus as claimed in claim 1, is characterized in that, is also connected with respectively the GPS global positioning system display screen of unifying on the master cpu of described transmitter and receiver.

4. pseudo-random code electrical prospecting apparatus as claimed in claim 1, is characterized in that, is also provided with power module, reset circuit, debug circuit and clock frequency synthesizer on described receiver.

5. pseudo-random code electrical prospecting apparatus as claimed in claim 1, is characterized in that, the DSP of described receiver is provided with for storing the SRAM of its data that are disposed.

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