CN204287509U - Pseudorandom spread spectrum electromagnetic wave tomography instrument - Google Patents
Pseudorandom spread spectrum electromagnetic wave tomography instrument Download PDFInfo
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- CN204287509U CN204287509U CN201420818232.3U CN201420818232U CN204287509U CN 204287509 U CN204287509 U CN 204287509U CN 201420818232 U CN201420818232 U CN 201420818232U CN 204287509 U CN204287509 U CN 204287509U
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Abstract
The utility model relates to a kind of pseudorandom spread spectrum electromagnetic wave tomography instrument, this imager comprises the pseudo-random sequence generator, modulator, power amplifier and the emitting antenna that connect successively, and the signal receiving antenna connected successively, detuner, signal correction device and signal strength estimator, described signal correction device is connected with described pseudo-random sequence generator, described pseudo-random sequence generator is connected with isochronous controller, described isochronous controller is connected with data processing host, and described data processing host is connected with man-machine interface.The utility model when the conditions such as emitted energy, frequency of operation and detected object are substantially identical, can adopt pseudo-random code spread-spectrum technology that system both can have been made to have good anti-interference, can promote again the penetration range of detection to a certain extent.
Description
Technical field
The utility model relates to the chromatographic imaging system between well or between tunnel, refers to a kind of pseudorandom spread spectrum electromagnetic wave tomography instrument particularly and is embodied as the method for picture.
Background technology
At present, the maximum technical barrier that geophysics chromatography imaging technique faces be penetration range not and detection range and the conflicting problem of resolution.Geophysics tomography is roughly divided into two large class, i.e. electromagnetic wave tomography and elastic wave tomographies, and electromagnetic wave tomography has magnetography and absorption coefficient imaging two kinds between well, and the former frequency of operation is 10Hz-10KHz, and imaging parameters is formation resistivity.Current the method is mainly used in reservoir exploration, and in non-metallic casing well, it is thoroughly apart from reaching 400m-500m, typical instrument with U.S.'s XHB2000 type EM imaging measurement system for representative; The latter's frequency of operation is 0.1MHz-35MHz, imaging parameters is that stratum is to electromagnetic absorption coefficient, typical instrument has domestic JW-4, JW-5 type Underground Electromagnetic Waves instrument and WKT-6 type electromagnetic wave underground electromagnetic wave perradiator etc., this instrument is mainly used in engineering investigation and coalfield and the ore explorations etc. such as urban construction, road and rail, water conservancy and hydropower, and it is thoroughly apart from reaching 100m-200m.Report: Electromagnetic CT is when transmission frequency is 0.3 million, and the maximum penetration distance in complete limestone is 500m, but its case history is extremely rare.
In engineering investigation, usually utilize one domestic or import 24 road (there is employing in 12 Dao Huo 48 roads) seismograph mixes detonator, explosive or sparker source and a series of well geophone just can carry out seismic tomography work.In petroleum industry, first to consider High Temperature High Pressure problem and other problem in well, must specialized equipment be adopted.In addition the tomography of petroleum prospecting also relates to large thoroughly apart from problem, and existing electromagnetic wave and elastic wave chromatography imaging technique are had little scope for one's talents.Therefore, petroleum industry mainly uses surface seismic method of exploration.
From current technical research, mainly there is the problem of large distance thoroughly and high resolving power detection thereof in geophysics chromatography imaging technique, and the resolution of geophysics chromatography imaging technique is by the restriction of two aspect factors: one is the frequency transmitted; Two is the density of ray, that is the size of imaging grid.Under the frequency of operation condition of above-mentioned conventional electromagnetic wave tomography instrument at present, resolution is lower, and front existing technology can't overcome the above problems well.
Summary of the invention
In view of above-mentioned the deficiencies in the prior art, the utility model object is overcome above-mentioned the deficiencies in the prior art and provide a kind of pseudorandom spread spectrum electromagnetic wave tomography instrument, the utility model can when the conditions such as emitted energy, frequency of operation and detected object be substantially identical, adopt pseudo-random code spread-spectrum technology that system both can have been made to have good anti-interference, the penetration range of detection can be promoted again to a certain extent.
The technical scheme realizing the employing of the utility model object is a kind of pseudorandom spread spectrum electromagnetic wave tomography instrument, and this imager comprises:
Ground host machine, comprise data processor, described data processor comprises isochronous controller, the first pseudo-random sequence generator, detuner, signal correction device and signal strength estimator, described detuner, signal correction device are connected with signal strength estimator successively electric signal, and described first pseudo-random sequence generator is connected with isochronous controller and signal correction device respectively;
First reel truck, is located at and launches near boring;
First well head pulley, is located at described transmitting boring and is positioned on the shaft mouth side on ground;
First cable, be around in described first reel truck, one end of described first cable is connected with described main frame, and the other end is placed in described transmitting boring by described first well head pulley;
Second reel truck, is located at and receives near boring;
Second well head pulley, is located at described reception boring and is positioned on the shaft mouth side on ground;
Second cable, be around in described second reel truck, one end of described second cable is connected with described main frame, and the other end is placed in described reception boring by described second well head pulley;
Emitter, be located at described first cable and be positioned on one end of transmitting boring, described emitter comprises the second pseudo-random sequence generator, modulator, power amplifier and the signal emitting antenna that electric signal successively connects;
Receiving trap, be located at described second cable and be positioned on one end of reception boring, described receiving trap comprises signal receiving antenna, low noise amplifier, frequency mixer, the intermediate frequency amplifier that electric signal successively connects.
Further, described pseudorandom spread spectrum electromagnetic wave tomography instrument also comprises A/D converter, FIFO memory, dma controller, RAM and the SD card that electric signal successively connects, described A/D converter is connected with intermediate frequency amplifier and data processor respectively, and described RAM with SD card is connected with data processor respectively.
In technique scheme, described data processor is also connected with man-machine interface.
The utility model can when the conditions such as emitted energy, frequency of operation and detected object be substantially identical, adopt pseudo-random code spread-spectrum mode emitting electromagnetic wave, improve the signal to noise ratio (S/N ratio) of Received signal strength, the antijamming capability of raising system, thus increasing penetration range, reach the object of exact inversion underground medium inner structure, deep prospecting and engineering geology, hydrogeology, hazards control etc. can be widely used in and respectively explore industry.
Accompanying drawing explanation
Fig. 1 is the structural representation of the utility model pseudorandom spread spectrum electromagnetic wave tomography instrument.
Fig. 2 is the annexation schematic diagram of each parts in the utility model pseudorandom spread spectrum electromagnetic wave tomography instrument.
Embodiment
Below in conjunction with the drawings and specific embodiments, the utility model is described in further detail.
As shown in Figure 1, the utility model pseudorandom spread spectrum electromagnetic wave tomography instrument comprises the main frame 1 being located at ground, main frame 1 comprises data processor, and data processor comprises isochronous controller, the first pseudo-random sequence generator, detuner, signal correction device, signal strength estimator.Wherein, detuner, signal correction device are connected with signal strength estimator successively electric signal, and the first pseudo-random sequence generator is connected with isochronous controller and signal correction device respectively.The present embodiment data processor used is that DSP, DSP are also connected with man-machine interface.
The utility model also comprises the first reel truck 3, first well head pulley 4, first cable 2, and the second reel truck 6, second well head pulley 7 and the second cable 8, and wherein, the first reel truck 3 is located at transmitting boring 10 and is positioned near the well head on ground; First well head pulley 3 is located at transmitting boring 10 and is positioned on the shaft mouth side on ground; First cable 2 is around on the first reel truck 3, one end 2.1 of first cable 2 is connected with main frame 1, the other end 2.2 is placed in by the first well head pulley 3 to be launched in boring 10, first cable 2 is positioned at the other end 2.2 launching boring 11 and is provided with emitter 5, and emitter 5 comprises pseudo-random sequence generator, modulator, power amplifier and the signal emitting antenna that electric signal successively connects.Second reel truck 7 is located at reception boring 11 and is positioned near the well head on ground; Second well head pulley 7 is located at reception boring 11 and is positioned on the shaft mouth side on ground; Second cable 8 is around on the second reel truck 6, one end 8.1 of second cable 8 is connected with main frame 1, the other end 8.2 is placed in by the second well head pulley 7 and receives in boring 11, second cable 8 is positioned at the other end 8.2 receiving boring 11 and is provided with receiving trap 9, and receiving trap 9 comprises signal receiving antenna, low noise amplifier, frequency mixer, the intermediate frequency amplifier that electric signal successively connects.
The utility model by rotation first well head pulley 3, thus pulls the first cable 2, first cable 2 to drive emitter 5 freely up and down to move in transmitting boring 10; In like manner, by rotating the second well head pulley 7, thus the second cable 8, second cable 8 is pulled to drive receiving trap 9 freely up and down to move in transmitting boring 11.
Described whole system device sends synch command by main frame 1 control synchronization controller by the first cable 2 and the second cable 8, carries out synchro control.
The course of work of the utility model pseudorandom spread spectrum electromagnetic wave tomography instrument is as follows:
The pseudo random signal being controlled by ground host machine 1 to produce is delivered to through cable and is launched in boring 10 in emitter 5, after modulator and power amplifier, by emitting antenna by pseudorandom radiates in stratum.In reception boring 11, received by the electromagnetic wave signal in stratum by receiving antenna 9, being sampled by sampling system keeps, and through cable transfer in ground host machine 1, carries out despreading process, obtains electromagnetic intensity estimated value, carry out imaging processing by CT imaging software.The work of launching in boring 10 and reception boring 11 holes carries out synchro control by ground host machine 1.
In the utility model, pseudo-random sequence is chosen as follows:
Pseudo-random code spread-spectrum technology is utilized to improve the signal to noise ratio (S/N ratio) of Received signal strength, relevant to the code length of pseudo-random sequence.Generally, pseudo-random sequence is long, and the signal to noise ratio (S/N ratio) of Received signal strength is high, but test speed reduces.Choosing of pseudo-random code sequence can choose suitable code sequence according to the signal intensity of test site.
Modulation system and modulation:
Pseudorandom spread spectrum electromagnetic wave tomography instrument, directly using pseudo-random sequence as baseband signal, carries out 2PSK modulation to carrier wave.
The utility model modulation /demodulation used and correlator algorithm as follows:
The signal that receiving antenna receives amplifies through low noise amplifier (LNA), and enter frequency mixer, generating center frequency is f
cintermediate-freuqncy signal, then carry out frequency-selecting amplification by intermediate frequency amplifier, this signal is undertaken after analog to digital conversion stored in data-carrier store (RAM) by high-speed AD.Demodulation and the correlator of signal pass through software simulating by DSP.
If intermediate-freuqncy signal is
Wherein, n (t) is noise signal, a
nfor signal intensity, s
nfor not returning 0 pseudo-random code sequence, g (t) for pulse width be T
ssingle rect.p..
V (t) with
mixing, and obtain restituted signal through low-pass filtering
Wherein n
lt () is that the noise in n (t) midband remains.
Correlator calculates by (3) formula
Wherein, τ=jT
s, j=0, ± 1, ± 2 ...
Signal intensity is estimated:
By (4) formula, the estimation of signal intensity
Wherein, M is pseudo-random code sequence s
ncode length.
The utility model electro-magnetic wave absorption coefficient CT tomographic process is as follows:
A. data processing
Approximate for electromagnetic wave regarding as, is linearly propagated, adopts ray tracing technique, imaging square profile is divided into m × n little square shaped cells (pixel).Assuming that f (x, y) represents the attenuation function of electromagnetic wave unit distance, i.e. absorption coefficient image function M (x, y).Article i-th, ray L
ithrough the ray L in a jth pixel
ijlength be l
ij, then M (x, y) is along L
ijradon transformation for mula be
In formula, M
j(x, y) is the absorption coefficient of a jth image-generating unit, and the mean value in this unit is X
j.
When ray is n bar, then above-mentioned equation (5) can be changed into
l
i1X
1+l
i2X
2+…+l
imX
m＝C
i(6)
Namely
Being write as matrix form is
I.e. LX=C (9)
In above formula, L=(l
ij)
n × mfor matrix of coefficients, be determined by the geometrical factor of radiation profile; X=(X
j)
mfor unknown number matrix, namely absorption coefficient; C=(C
i)
nfor constant matrices, the absorption value of the ray terminal of namely imposing out according to field intensity and the initial fields of receiving antenna.
B. imaging
CT tomography is exactly that the absorption coefficient value corresponding to each pixel is synthesized an absorption coefficient isogram.The absorption coefficient value calculated is considered as the mean absorption coefficient of each pixel, then adopts rational interpolation method to calculate these points, set up a space curved surface V=M (x, y).With V=V
0cut this curved surface, the projection of the curve intercepted on xy face is required absorption coefficient isogram.
Image interpretation:
According to anomaly of wave velocity point or region on tried to achieve electro-magnetic wave absorption coefficient isogram, descend anomalous geologic body size and position definitely.
Claims (3)
1. a pseudorandom spread spectrum electromagnetic wave tomography instrument, is characterized in that, comprising:
Ground host machine, comprise data processor, described data processor comprises isochronous controller, the first pseudo-random sequence generator, detuner, signal correction device and signal strength estimator, described detuner, signal correction device are connected with signal strength estimator successively electric signal, and described first pseudo-random sequence generator is connected with isochronous controller and signal correction device respectively;
First reel truck, is located at and launches near boring;
First well head pulley, is located at described transmitting boring and is positioned on the shaft mouth side on ground;
First cable, be around in described first reel truck, one end of described first cable is connected with described main frame, and the other end is placed in described transmitting boring by described first well head pulley;
Second reel truck, is located at and receives near boring;
Second well head pulley, is located at described reception boring and is positioned on the shaft mouth side on ground;
Second cable, be around in described second reel truck, one end of described second cable is connected with described main frame, and the other end is placed in described reception boring by described second well head pulley;
Emitter, be located at described first cable and be positioned on one end of transmitting boring, described emitter comprises the second pseudo-random sequence generator, modulator, power amplifier and the signal emitting antenna that electric signal successively connects;
Receiving trap, be located at described second cable and be positioned on one end of reception boring, described receiving trap comprises signal receiving antenna, low noise amplifier, frequency mixer, the intermediate frequency amplifier that electric signal successively connects.
2. pseudorandom spread spectrum electromagnetic wave tomography instrument according to claim 1, characterized by further comprising A/D converter, FIFO memory, dma controller, RAM and SD card that electric signal successively connects, described A/D converter is connected with intermediate frequency amplifier and data processor respectively, and described RAM with SD card is connected with data processor respectively.
3. pseudorandom spread spectrum electromagnetic wave tomography instrument according to claim 1, is characterized in that: described data processor is also connected with man-machine interface.
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| CN201420818232.3U CN204287509U (en) | 2014-12-22 | 2014-12-22 | Pseudorandom spread spectrum electromagnetic wave tomography instrument |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104536052A (en) * | 2014-12-22 | 2015-04-22 | 武汉市工程科学技术研究院 | Pseudorandom spectrum-spread electromagnetic wave tomographic imaging instrument and method for achieving imaging |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104536052A (en) * | 2014-12-22 | 2015-04-22 | 武汉市工程科学技术研究院 | Pseudorandom spectrum-spread electromagnetic wave tomographic imaging instrument and method for achieving imaging |
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