Anti-interference engineering transient electromagnetic instrument

Abstract

The utility model discloses an anti-interference engineering transient electromagnetic instrument, which comprises a shell, a transmitting unit, a receiving unit and a control unit, wherein the transmitting unit, the receiving unit and the control unit are arranged in the shell; the transmitting unit comprises a transmitter and a transmitting coil; the receiving unit comprises a shielding assembly and a signal receiving assembly, the shielding assembly is of a multi-layer shielding structure, and each layer of shielding structure correspondingly absorbs interference signals of different frequencies; the control unit comprises a main control board, and the main control board is in signal connection with the transmitting unit and the receiving unit. Interference of different frequency bands is shielded and filtered out through the shielding assembly, then attenuation characteristics of a secondary field are detected through the signal receiving assembly, underground resistivity distribution is inversed in combination with time domain analysis, then underground electrical structure characteristics are analyzed, a traditional single-layer metal cover is replaced with layered gradient shielding, and interference of different frequency bands is filtered out in a targeted mode.

Description

TECHNICAL FIELD

[0001] The embodiment of the utility model belongs to engineering detection technical field, more particularly, it relates to an anti-interference engineering transient electromagnetic instrument. BACKGROUND

[0002] As the core equipment of underground nondestructive detection, the engineering transient electromagnetic instrument is widely used in mine hazard investigation, tunnel geological prediction, urban pipeline detection and other fields. In complex working conditions (such as near high-voltage substation, narrow mine roadway), the equipment needs to maintain high-precision detection in strong electromagnetic interference, limited space and harsh temperature and humidity environment. However, the traditional transient electromagnetic instrument is limited by the problems of insufficient shielding effectiveness, weak anti-interference ability and large volume, etc. It has low deployment efficiency in narrow space, and is easily interfered by power frequency noise, high-frequency communication signal, etc. The effective signal collection rate is less than 50%, which seriously restricts the engineering safety and detection efficiency.

[0003] The current mainstream technical solution mainly adopts single-layer metal shielding shell (such as aluminum or copper) combined with software filtering algorithm (such as wavelet transform, adaptive filtering) to suppress interference. Its advantages are: simple structure: single-layer metal shell has low processing cost and is easy to maintain; software flexibility: specific frequency band noise (such as 50Hz power frequency) can be filtered through post-processing algorithm; basic anti-interference ability: the shielding effectiveness of medium and high frequency interference (>1MHz) can reach 30-40dB. In addition, some improved schemes adopt fixed double-coil differential structure, which can offset part of the environmental noise through hardware circuit and improve the real-time performance of the signal.

[0004] Although the existing technology has basic anti-interference ability, it still has the following defects: single shielding frequency band: single-layer metal shell is only effective for high frequency, and has almost no shielding effect for low frequency magnetic field (such as power frequency), and the thick metal structure (≥15kg) leads to poor portability; signal processing lag: software filtering introduces ≥10ms delay, which cannot meet the real-time detection requirement, and relies on artificial modeling, which is invalid in dynamic interference scene; insufficient mechanical adaptability: the fixed coil and the shielding cabin are designed separately, and need to be repeatedly leveled during deployment, which takes up to 15 minutes in inclined and narrow space, and the coil spacing is easily affected by deformation, leading to noise cancellation failure; poor compatibility in all scenes: the existing scheme does not consider the synergistic mechanism of gradient interference attenuation and hardware noise reduction, and in complex engineering sites (such as mine substation) with strong interference and multi-frequency interference, the signal-to-noise ratio is still less than 20dB, and the data reliability is difficult to guarantee. UTILITY MODEL CONTENTS

[0005] In view of the above defects or improvement needs of the prior art, the utility model provides an anti -interference's engineering transient electromagnetic instrument, through shielding assembly shielding filter out different frequency band interference, then through signal receiving subassembly detects the attenuation characteristic of secondary field, combines time domain analysis and inverts underground resistivity distribution, and then resolves the underground electric property structure characteristics, replaces the traditional single layer metal cover through the layered gradient shielding, and the different frequency band interference is filtered out pertinently.

[0006] In order to realize the above-mentioned purpose, the utility model embodiment provides an anti -interference's engineering transient electromagnetic instrument, including shell, be located in the transmitting unit, receiving unit and control unit in the shell,

[0007] The transmitting unit includes transmitter and transmitting coil,

[0008] The receiving unit includes shielding assembly and signal receiving assembly, the shielding assembly is multilayer shielding structure, and each layer shielding structure corresponds to absorb different frequency interference signals,

[0009] The control unit includes main control board, and the main control board is signal connected with transmitting unit, receiving unit.

[0010] Further, the receiving unit further includes a receiving bracket fixed inside the shell and a preamplifier arranged at the front end of the receiving bracket.

[0011] Further, the receiving bracket is cylindrical, and the rear end is fixed to the inner wall of the shell, and the front end is open.

[0012] The preamplifier is detachably connected to the front end opening of the receiving bracket, for amplifying weak induction signals and suppressing high-frequency noise.

[0013] Further, the shielding assembly is arranged in the inner cylinder of the receiving bracket and connected with the receiving bracket through interference fit, and sealed inside the receiving bracket through the preamplifier.

[0014] The shielding assembly is a cylindrical multilayer structure, which comprises a low-frequency shielding layer, a medium-frequency absorbing layer and a high-frequency absorbing layer from outside to inside.

[0015] Further, the low-frequency shielding layer is made of conductive rubber, which is a silica gel substrate, and the silica gel substrate is doped with carbon nanotubes and silver powder to form a conductive network, which is used as a Faraday cage to conduct away low-frequency electromagnetic interference.

[0016] The rear end of the low-frequency shielding layer is connected with the shell by a metal pressing strip, and grounded through the shell.

[0017] The middle frequency absorption layer is made of a permalloy, and the permalloy sheet is stamped into a wave-shaped fold structure and relies on the permalloy to consume the energy of the middle frequency electromagnetic by magnetic domain flipping.

[0018] The high frequency absorption layer is formed by winding and stacking a plurality of nanocrystalline strips.

[0019] Further, gaps are left between the middle frequency absorption layer and the low frequency shielding layer and between the high frequency absorption layer and the middle frequency absorption layer.

[0020] Further, a nylon support is arranged in the gap between the middle frequency absorption layer and the low frequency shielding layer for supporting and fixing the middle frequency absorption layer.

[0021] The gap between the high frequency absorption layer and the middle frequency absorption layer is filled with foam for isolating the high frequency absorption layer and the middle frequency absorption layer.

[0022] Further, a cylindrical cavity is left in the high frequency absorption layer, and the cavity is filled with an inner filling layer made of wave-absorbing foam impregnated with ferrite powder.

[0023] Further, the inner filling layer is hollowed in the middle as a receiving cavity, and the signal receiving assembly is arranged in the receiving cavity.

[0024] The signal receiving assembly comprises a columnar coil substrate and main receiving coils and auxiliary receiving coils arranged at two ends of the coil substrate.

[0025] Further, the main receiving coils and the auxiliary receiving coils are symmetrically arranged and fixed on the two end faces of the coil substrate.

[0026] The signal receiving assembly further comprises a differential amplification circuit connected with the main receiving coils and the auxiliary receiving coils.

[0027] Overall, the above technical scheme of the utility model can achieve the following beneficial effects compared with the prior art:

[0028] 1. The engineering transient electromagnetic instrument comprises a shielding assembly and a signal receiving assembly, the shielding assembly is a multi-layer shielding structure, each layer of the shielding structure absorbs different frequency interference signals, different frequency band interference is filtered out through the shielding assembly, then the signal receiving assembly detects the attenuation characteristics of the secondary field, the underground resistivity distribution is inverted combined with time domain analysis, and then the underground electrical structure characteristics are analyzed.

[0029] 2. The utility model discloses an engineering transient electromagnetic instrument which replaces the traditional single-layer metal cover with a layered gradient shield, filters out different frequency band interference, and is lighter than the metal cover, making it more convenient to use the engineering transient electromagnetic instrument outdoors. The multi-layer structure is better at heat dissipation and ventilation than the sealed metal cover, solving the problem of heat accumulation in the metal cover.

[0030] 3. The utility model discloses an engineering transient electromagnetic instrument which receives signals containing real signals and noise through the main receiving coil, and receives signals containing only environmental noise through the auxiliary receiving coil. After differential amplification, the noise component is cancelled, and the real signal is retained. Since the distance between the main receiving coil and the auxiliary receiving coil is fixed, the phase difference of the two coils under interference signals is constant, ensuring the effectiveness of differential cancellation and improving the power frequency interference suppression capability without the need for post-processing software filtering. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a whole structure schematic diagram of an anti-interference engineering transient electromagnetic instrument according to an embodiment of the utility model;

[0032] Figure 2 It is an internal structure schematic diagram of an anti-interference engineering transient electromagnetic instrument according to an embodiment of the utility model;

[0033] Figure 3 It is a receiving unit structure sectional view of an anti-interference engineering transient electromagnetic instrument according to an embodiment of the utility model;

[0034] Figure 4 It is a receiving unit structure sectional view of an anti-interference engineering transient electromagnetic instrument according to an embodiment of the utility model.

[0035] In all the drawings, the same reference signs represent the same technical features, specifically: 1 - shell, 2 - transmitting unit, 21 - transmitter, 22 - transmitting coil, 3 - receiving unit, 31 - receiving support, 32 - preamplifier, 33 - shielding assembly, 331 - low-frequency shielding layer, 332 - medium-frequency absorbing layer, 333 - high-frequency absorbing layer, 334 - inner filling layer, 34 - signal receiving assembly, 341 - coil substrate, 342 - main receiving coil, 343 - auxiliary receiving coil, 4 - control unit, 41 - main control board, 42 - data processing module, 43 - human-computer interaction module, 5 - battery, 6 - signal transmission unit. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the utility model clearer, the utility model will be described in further detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the utility model and are not used to limit the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0037] As shown in Figures 1-4 The utility model embodiment provides an anti -interference's engineering transient electromagnetic instrument, including: shell 1, be located in the transmitting unit 2 of shell 1, receiving unit 3 and control unit 4. The transmitting unit 2 is used to emit pulse current to the ground to form a primary field, and after power off, eddy current is generated in the underground conductive medium due to electromagnetic induction and forms a secondary field. The receiving unit 3 includes shielding assembly 33 and signal receiving assembly 34, the shielding assembly 33 is multilayer shielding structure, and each layer of shielding structure corresponds to absorb different frequency interference signals, and different frequency band interference is filtered out through shielding assembly 33 shielding, then through signal receiving assembly 34 detects the attenuation characteristic of secondary field, combines time domain analysis and inverts underground resistivity distribution, and then analyzes the underground electrical structure characteristics.

[0038] The transmitting unit 2 includes transmitter 21 and transmitting coil 22. Wherein, the transmitter 21 includes energy storage capacitor and switching circuit, is used to produce high-power transient pulse current. The transmitting coil 22 is connected with the current output end of transmitter 21, is composed of single turn, multiple turns or overlapping return line, is used to emit pulse current to the ground to form a primary field.

[0039] The receiving unit 3 further includes receiving support 31 fixed in the inside of shell 1 and preamplifier 32 located at the front end of receiving support 31. The receiving support 31 is cylindrical, and the rear end is fixed on the inner wall of shell 1, and the front end is open. The preamplifier 32 is detachably connected at the front end opening of receiving support 31, is used to amplify weak induction signal and suppress high-frequency noise.

[0040] The shielding assembly 33 is arranged in the inner cylinder of the receiving support 31, connected with the receiving support 31 through interference fit, and sealed inside the receiving support 31 by the preamplifier 32. The shielding assembly 33 is a cylindrical multilayer structure, which is composed of a low-frequency shielding layer 331, a medium-frequency absorbing layer 332 and a high-frequency absorbing layer 333 from outside to inside. The low-frequency shielding layer 331 is made of conductive rubber, which is a silica gel substrate doped with carbon nanotubes and silver powder to form a conductive network. The conductive network is used as a Faraday cage to lead away low-frequency electromagnetic interference. The rear end of the low-frequency shielding layer 331 is connected with the shell 1 through a metal pressing strip, and is grounded through the shell 1. The medium-frequency absorbing layer 332 is made of permalloy, which is a permalloy sheet stamped into a wave-shaped corrugated structure. The medium-frequency electromagnetic energy is consumed by the magnetic domain flipping of the permalloy. The high-frequency absorbing layer 333 is composed of multiple layers of nanocrystalline strip material, preferably Fe-Si-B nanocrystalline strip material, which is wound in a concentric circular ring shape to absorb high-frequency noise by utilizing the high-frequency magnetic hysteresis loss characteristics of nanocrystalline. The layered gradient shielding replaces the traditional single-layer metal cover, specifically filters out different frequency band interference, and the composite material is lighter than the metal cover, which is more convenient for the use of the engineering transient electromagnetic instrument outdoors. At the same time, the multilayer structure has better heat dissipation and ventilation performance than the sealed metal cover, solving the problem of easy heat accumulation in the metal cover.

[0041] As a further preferred, the medium-frequency absorbing layer 332 and the low-frequency shielding layer 331, the high-frequency absorbing layer 333 and the medium-frequency absorbing layer 332 are all left with gaps. The gap between the medium-frequency absorbing layer 332 and the low-frequency shielding layer 331 is provided with a nylon support for supporting and fixing the medium-frequency absorbing layer 332; the gap between the high-frequency absorbing layer 333 and the medium-frequency absorbing layer 332 is filled with foam, which isolates the high-frequency absorbing layer 333 and the medium-frequency absorbing layer 332 and eliminates part of the interference. The high-frequency absorbing layer 333 also has a cylindrical cavity inside, which is filled with an inner filling layer 334. The inner filling layer 334 is filled with wave-absorbing foam, which is polyurethane foam impregnated with ferrite powder. The porous structure of the polyurethane foam scatters and absorbs residual electromagnetic waves, reducing reflection.

[0042] The inner filling layer 334 is hollowed in the middle as a receiving cavity, and the signal receiving assembly 34 is arranged in the receiving cavity. The signal receiving assembly 34 comprises a columnar coil substrate 341 and a main receiving coil 342 and a sub-receiving coil 343 arranged at two ends of the coil substrate 341. The main receiving coil 342 and the sub-receiving coil 343 are symmetrically arranged and fixed on the two end surfaces of the coil substrate 341. The signal receiving assembly 34 further comprises a differential amplification circuit connected with the main receiving coil 342 and the sub-receiving coil 343, and the signals received by the main receiving coil 342 and the sub-receiving coil 343 are processed by the differential amplification circuit. The main receiving coil 342 receives a signal containing a real signal and noise, while the sub-receiving coil 343 collects a signal containing only environmental noise. After differential amplification, the noise component is cancelled and the real signal is retained. Since the distance between the main receiving coil 342 and the sub-receiving coil 343 is fixed, the phase difference of the interference signals received by the two coils is constant, which ensures the effectiveness of differential cancellation and improves the power frequency interference suppression capability without the need for post-processing software filtering.

[0043] The control unit 4 comprises a main control board 41, a data processing module 42 arranged on the main control board 41 and a man-machine interaction module 43. The main control board 41 is signal connected with the transmitting unit 2 and the receiving unit 3, and is used for controlling the parameters of the transmitting unit 2 and the receiving unit 3. The data processing module 42 is used for storing the signals received by the receiving unit 3 and processing the signals, and outputs visual chart information. The man-machine interaction module 43 is arranged on the top surface of the shell 1 outside, and comprises a display screen and an operation knob, which are used for displaying the visual chart information output by the data processing module 42 and adjusting the parameters of the transmitting unit 2 and the receiving unit 3.

[0044] The shell 1 further comprises a battery 5 for supplying power to the transmitting unit 2, the receiving unit 3 and the control unit 4.

[0045] The shell 1 further comprises a signal transmission unit 6 comprising a wireless transmission module and a wired transmission module, which are used for connecting external equipment to download the information stored in the data processing module 42.

[0046] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An interference-immune engineering transient electromagnetic instrument, characterized in that, The utility model relates to a kind of radio frequency identification reader, including shell (1), be arranged in the transmitter unit (2) of the shell (1), receiving unit (3) and control unit (4); The transmitter unit (2) includes transmitter (21) and transmitting coil (22); The receiving unit (3) includes shielding assembly (33) and signal receiving assembly (34), the shielding assembly (33) is multilayer shielding structure, and each layer shielding structure corresponds to absorb different frequency interference signal; The control unit (4) includes main control board (41), and the main control board (41) is connected with transmitter unit (2), receiving unit (3) signal.

2. The anti-interference engineering transient electromagnetic instrument according to claim 1, characterized in that, The receiving unit (3) further includes receiving support (31) fixed in the inside of the shell (1) and preamplifier (32) arranged in the front end of the receiving support (31).

3. The anti-interference engineering transient electromagnetic instrument according to claim 2, characterized in that, The receiving support (31) is cylindrical, and its rear end is fixed on the inner wall of the shell (1), and the front end is open; The preamplifier (32) is detachably connected to the front end opening of the receiving support (31), for amplifying weak induction signal and inhibiting high-frequency noise.

4. The anti-interference engineering transient electromagnetic instrument according to claim 3, characterized in that, The shielding assembly (33) is arranged in the inner cylinder of the receiving support (31), and is connected between the receiving support (31) by interference fit, and is sealed in the receiving support (31) by the preamplifier (32); The shielding assembly (33) is a cylindrical multilayer structure, which is composed of a low-frequency shielding layer (331), a medium-frequency absorbing layer (332) and a high-frequency absorbing layer (333) from outside to inside.

5. The anti-interference engineering transient electromagnetic instrument according to claim 4, characterized in that, The low-frequency shielding layer (331) is made of conductive rubber, which is a silica gel substrate doped with carbon nanotubes and silver powder to form a conductive network. The conductive network is used as a Faraday cage to lead away low-frequency electromagnetic interference. The rear end of the low-frequency shielding layer (331) is connected to the shell (1) by a metal pressing strip, which is grounded through the shell (1). The medium-frequency absorbing layer (332) is made of permalloy, which is a thin sheet of permalloy stamped into a wave-shaped corrugated structure. The medium-frequency electromagnetic energy is consumed by the permalloy through magnetic domain flipping. The high-frequency absorbing layer (333) is made of multiple layers of nanocrystalline strip material wound and stacked in a concentric circular ring shape.

6. The anti-interference engineering transient electromagnetic instrument according to claim 4, characterized in that, There is a gap between the medium-frequency absorbing layer (332) and the low-frequency shielding layer (331), and between the high-frequency absorbing layer (333) and the medium-frequency absorbing layer (332).

7. The anti-interference engineering transient electromagnetic instrument according to claim 6, characterized in that, A nylon bracket is arranged in the gap between the medium-frequency absorbing layer (332) and the low-frequency shielding layer (331) to support and fix the medium-frequency absorbing layer (332). The gap between the high-frequency absorbing layer (333) and the medium-frequency absorbing layer (332) is filled with foam to isolate the high-frequency absorbing layer (333) and the medium-frequency absorbing layer (332).

8. The anti-interference engineering transient electromagnetic instrument according to claim 7, characterized in that, The high-frequency absorbing layer (333) also has a cylindrical cavity inside, which is filled with an inner filling layer (334). The inner filling layer (334) is filled with wave-absorbing foam, which is polyurethane foam impregnated with ferrite powder.

9. The anti-interference engineering transient electromagnetic instrument according to claim 8, characterized in that, The inner filling layer (334) is hollow in the middle to form a receiving cavity, and the signal receiving assembly (34) is arranged in the receiving cavity. The signal receiving assembly (34) comprises a columnar coil substrate (341) and a main receiving coil (342) and a sub-receiving coil (343) arranged at two ends of the coil substrate (341).

10. The anti-interference engineering transient electromagnetic instrument according to claim 9, characterized in that, The main receiving coil (342) and the sub-receiving coil (343) are symmetrically arranged and fixed on two end faces of the coil substrate (341). The signal receiving assembly (34) further comprises a differential amplification circuit connected with the main receiving coil (342) and the sub-receiving coil (343).

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