A large-depth inductive electromagnetic detection equipment and a detection method

Abstract

The application discloses a large-depth inductive electromagnetic detection equipment and method, which comprises an array antenna, the array antenna is composed of a vertical direction transmitting coil and a plurality of horizontal direction receiving coils, the transmitting coil is electrically connected with a wideband signal transmitter through an impedance conversion network, and the plurality of horizontal direction receiving coils are divided into two groups, each group is electrically connected with a wideband preamplifier in a wideband receiving circuit system through an impedance conversion network. The detection equipment disclosed by the application is mainly used for detecting urban underground deep target bodies, overcomes the shortcomings in the prior art surface nondestructive electromagnetic detection technology, and has a detection depth of 0-80 meters, and greatly improves the nondestructive noncontact large-buried-depth detection capability.

Description

Technical Field

[0001] This invention belongs to the field of geological exploration equipment, and specifically relates to a deep-penetration inductive electromagnetic detection equipment and detection method in this field, which can measure target objects in complex spaces deep underground (0-80m) based on the basic principle of electromagnetic induction. Background Technology

[0002] Currently, commonly used methods for urban underground space detection both domestically and internationally include electromagnetic induction (including active source and passive source methods), ground-penetrating radar (GPR), and DC resistivity methods. Electromagnetic induction and GPR both belong to the electromagnetic detection method family and are currently the most commonly used methods for detecting underground targets. Electromagnetic induction detects underground targets by inducing a secondary electromagnetic field; it is simple, low-cost, and efficient, but it faces difficulties in precise target identification. GPR detects underground targets by receiving high-frequency electromagnetic waves reflected from them, offering advantages such as high resolution, ease of operation, and imaging capabilities; however, due to the significant attenuation of high-frequency electromagnetic waves, it has limitations in detection depth. Summary of the Invention

[0003] The technical problem to be solved by this invention is to improve the non-destructive, non-contact deep-buried detection capability and to provide a deep-depth inductive electromagnetic detection equipment and detection method.

[0004] The present invention adopts the following technical solution:

[0005] An improved deep-field inductive electromagnetic detection equipment includes an array antenna composed of a vertically oriented transmitting coil and several horizontally oriented receiving coils. The transmitting coils are electrically connected to a broadband signal transmitter via an impedance conversion network. The several horizontally oriented receiving coils are divided into two groups, each group being electrically connected to a broadband preamplifier low-noise amplifier within a broadband receiving circuit system via an impedance conversion network. The broadband receiving circuit system includes a broadband preamplifier low-noise amplifier, an emitter follower amplifier, a variable gain amplifier, an ultra-narrowband filter, a driver amplifier, and amplitude and phase detectors connected in sequence. The two broadband receiving circuit systems share a single amplitude and phase detector, which is electrically connected to a high-precision synchronous acquisition system, which in turn is electrically connected to a DSP main control system.

[0006] Furthermore, the broadband signal transmitter includes a broadband signal generator, a resonant filter, and a digitally controllable high-gain power amplifier connected in sequence, and the digitally controllable high-gain power amplifier is also electrically connected to an impedance conversion network.

[0007] Furthermore, the broadband signal transmitter transmits broadband signals ranging from 10kHz to 5MHz.

[0008] Furthermore, the high-precision synchronous acquisition system includes a high-temperature rail-to-rail operational amplifier, a high-precision reference power supply, and a multi-channel high-precision synchronous acquisition analog-to-digital converter.

[0009] Furthermore, the DSP main control system includes a high-speed floating-point DSP TMS320F28335 main controller, a high-temperature multi-channel reference voltage, a high-speed crystal oscillator, and a large-capacity memory, driven by isolated CAN bus communication.

[0010] An improved method for deep-field inductive electromagnetic detection involves a broadband signal transmitter emitting a 10kHz to 5MHz broadband signal. This signal is transmitted to a vertical transmitting coil via an impedance conversion network, generating a primary field. This primary field creates eddy currents in the strata, which in turn generate a secondary field. The secondary field is radiated through the strata and received by a horizontal receiving coil. It is then sent to a broadband receiving circuit system via the impedance conversion network. Within this system, the signal is amplified by a broadband preamplifier with low noise, driven by an emitter follower amplifier, amplified by a variable gain amplifier, and filtered by an ultra-narrowband filter. Finally, it is sent by a drive amplifier to an amplitude and phase detector to be converted into amplitude and phase signals. These signals are then digitized by a high-precision synchronous acquisition system and sent to a DSP main control system for data storage and uploading.

[0011] The beneficial effects of this invention are:

[0012] The detection equipment disclosed in this invention is mainly used for detecting deep underground targets in cities. It overcomes the shortcomings of existing non-destructive electromagnetic detection technologies on the surface, achieving a detection depth of 0-80 meters, significantly improving the capability of non-destructive, non-contact, deep-buried detection. Utilizing high-sensitivity electromagnetic detection and identification technology, it enables rapid positioning and inversion of small targets, greatly improving imaging resolution. Employing an antenna array, it can adapt to the needs of different detection scenarios, achieving large detection depths and high-precision target resolution.

[0013] The detection method disclosed in this invention, through horizontal and vertical multi-polarization inductive electromagnetic measurement, can eliminate the interference of background field direct-couple signals, effectively improving the detection depth and accuracy of complex spatial targets deep underground (0-80m). Employing a wide frequency band (10KHz~5MHz) with multiple operating frequencies, it can achieve scanning detection of complex spatial targets at different depths. Attached Figure Description

[0014] Figure 1 This is a block diagram of the detection equipment disclosed in Embodiment 1 of the present invention;

[0015] Figure 2 This is a block diagram of the array antenna in the detection equipment disclosed in Embodiment 1 of the present invention;

[0016] Figure 3 This is a block diagram of the broadband signal transmitter in the detection equipment disclosed in Embodiment 1 of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] Example 1, as Figure 1 As shown, this embodiment discloses a deep-depth inductive electromagnetic detection equipment, including an array antenna, such as... Figure 2 As shown, the array antenna consists of a vertically oriented transmitting coil and several horizontally oriented receiving coils. The transmitting coil acts as a broadband transmitting antenna, emitting a broadband signal into the ground to generate a primary field (low-frequency, time-harmonic field). The receiving coils act as receiving antennas, receiving the secondary field induced by deep underground anomalies. The transmitting coil is electrically connected to a broadband signal transmitter via an impedance transformation network, which is used to achieve impedance matching with the broadband signal transmitter. The several horizontally oriented receiving coils are divided into two groups. Each group is electrically connected to a broadband preamplifier low-noise amplifier within a broadband receiving circuit system via an impedance transformation network, which is used to achieve impedance matching with the broadband receiving circuit system. The aforementioned wideband receiving circuit system is used to perform low-noise amplification, filtering, phase and amplitude detection on multiple deep-seated target secondary field (electric field and magnetic field) signals. It includes a wideband preamplifier low-noise amplifier, an emitter follower amplifier, a variable gain amplifier, an ultra-narrowband filter, a driver amplifier, and amplitude and phase detectors connected in sequence. The two wideband receiving circuit systems share a single amplitude and phase detector, which is electrically connected to a high-precision synchronous acquisition system. The high-precision synchronous acquisition system is electrically connected to a DSP main control system.

[0019] like Figure 3 As shown, the broadband signal transmitter includes a broadband signal generator, a resonant filter, and a digitally controllable high-gain power amplifier connected in sequence. The digitally controllable high-gain power amplifier is also electrically connected to an impedance transformation network. The broadband signal transmitter transmits broadband signals from 10kHz to 5MHz.

[0020] The high-precision synchronous acquisition system includes a high-temperature rail-to-rail operational amplifier, a high-precision reference power supply, and a multi-channel high-precision synchronous acquisition analog-to-digital converter, which realizes the digital conversion of multiple electromagnetic wave analog signals.

[0021] The DSP main control system includes a high-speed floating-point DSP TMS320F28335 main controller, a high-temperature multi-channel reference voltage, a high-speed crystal oscillator, and a large-capacity memory. It is driven by isolated CAN bus communication to complete the calculation of digital signals and control and adjust the working status of the detection equipment.

[0022] The detection equipment disclosed in this embodiment employs a high-sensitivity sensing coil assembled into multiple horizontally and vertically polarized electric and magnetic field transmitting and receiving array antennas, enabling the transmission and acquisition of secondary field (inductive field) electromagnetic component signals at different depths. It utilizes an array antenna composed of multiple antennas with different transmit-receive spacings and multiple low-frequency (10kHz~5MHz) operating frequency bands to measure multi-component electromagnetic field information of deep underground targets. By employing time-harmonic and multi-frequency electromagnetic field measurement principles, it eliminates the influence of background signals through strong signal transmission, weak signal detection, strong interference suppression, and acquisition of electromagnetic components in horizontal and vertical dual-polarization directions. The high-precision weak magnetic antenna design technology effectively improves the detection capability of weak signals, breaking through the limitations of traditional geological exploration instruments in detecting shallow underground targets. It can detect complex spatial targets in deep underground environments (0-80m), achieving a resolution of the size of deep underground targets at 5% of the burial depth of the anomaly.

[0023] This embodiment also discloses a deep-depth inductive electromagnetic detection method. A broadband signal transmitter emits a broadband signal of 10kHz to 5MHz. This broadband signal is transmitted to the vertical transmitting coil through an impedance conversion network, generating a primary field (low-frequency, time-harmonic field). The primary field forms eddy currents in the stratum, and the eddy currents form a secondary field (inductive field, i.e., the secondary induced electromagnetic wave of the stratum anomaly, including electric and magnetic fields). The secondary field is radiated by the stratum and received by the horizontal receiving coil. It is then sent to the broadband receiving circuit system through the impedance conversion network. After being amplified by a broadband preamplifier low-noise amplifier, driven by an emitter follower amplifier, amplified by a variable gain amplifier, and filtered by an ultra-narrowband filter in the broadband receiving circuit system, it is sent by the driving amplifier to the amplitude and phase detectors to be converted into amplitude and phase signals. After being digitized by a high-precision synchronous acquisition system, it is sent to the DSP main control system for data storage and uploading.

[0024] The detection method disclosed in this embodiment uses a receiving coil to measure the secondary field (induced field, including electric and magnetic fields) generated by an anomaly in the deep underground (0-80m) depths. This signal is related to the size, location, resistivity, and dielectric constant of the anomaly. After obtaining the induced electromagnetic field information using an array antenna, the electrical parameters of the stratigraphic anomaly are interpreted geologically and imaged.

Claims

1. A deep-field inductive electromagnetic detection method, using a deep-field inductive electromagnetic detection equipment, including an array antenna, the array antenna consisting of a vertically oriented transmitting coil and several horizontally oriented receiving coils, the transmitting coils being electrically connected to a broadband signal transmitter via an impedance conversion network, the several horizontally oriented receiving coils being divided into two groups, each group being electrically connected to a broadband preamplifier low-noise amplifier within a broadband receiving circuit system via an impedance conversion network, the broadband receiving circuit system including a broadband preamplifier low-noise amplifier, an emitter follower amplifier, a variable gain amplifier, an ultra-narrowband filter, a driver amplifier, and an amplitude and phase detector connected in sequence, and the two broadband receiving circuit systems sharing a single amplitude and phase detector, which is electrically connected to a high-precision synchronous acquisition system, and the high-precision synchronous acquisition system is electrically connected to a DSP main control system, characterized in that: A broadband signal transmitter transmits a broadband signal of 10kHz to 5MHz. This broadband signal is transmitted to the vertical transmitting coil through an impedance conversion network, generating a primary field. The primary field forms eddy currents in the stratum, which in turn form a secondary field. The secondary field is radiated through the stratum and received by the horizontal receiving coil. It is then sent to the broadband receiving circuit system through the impedance conversion network. After being amplified by a broadband preamplifier low-noise amplifier, driven by an emitter follower amplifier, amplified by a variable gain amplifier, and filtered by an ultra-narrowband filter, the signal is sent by a drive amplifier to an amplitude and phase detector to be converted into amplitude and phase signals. After being digitized by a high-precision synchronous acquisition system, the signal is sent to the DSP main control system for data storage and uploading.

2. The method of claim 1, wherein: The broadband signal transmitter includes a broadband signal generator, a resonant filter, and a digitally controllable high-gain power amplifier connected in sequence. The digitally controllable high-gain power amplifier is also electrically connected to an impedance conversion network.

3. The method of claim 2, wherein: The broadband signal transmitter transmits broadband signals ranging from 10kHz to 5MHz.

4. The method of claim 1, wherein: The high-precision synchronous acquisition system includes a high-temperature rail-to-rail operational amplifier, a high-precision reference power supply, and a multi-channel high-precision synchronous acquisition analog-to-digital converter.

5. The deep-depth inductive electromagnetic detection method according to claim 1, characterized in that: The DSP main control system includes a high-speed floating-point DSP TMS320F28335 main controller, a high-temperature multi-channel reference voltage, a high-speed crystal oscillator, and a large-capacity memory, driven by isolated CAN bus communication.

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