CN115356562A - Near-field positioning system and method for radiation disturbance source of motor train unit - Google Patents
Near-field positioning system and method for radiation disturbance source of motor train unit Download PDFInfo
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- CN115356562A CN115356562A CN202210974104.7A CN202210974104A CN115356562A CN 115356562 A CN115356562 A CN 115356562A CN 202210974104 A CN202210974104 A CN 202210974104A CN 115356562 A CN115356562 A CN 115356562A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/001—Measuring interference from external sources to, or emission from, the device under test, e.g. EMC, EMI, EMP or ESD testing
Abstract
The invention discloses a near field positioning system and a near field positioning method for a radiation disturbance source of a motor train unit, wherein the near field positioning system comprises the following steps: the device comprises an electric field probe, a magnetic field probe, a preamplifier and a portable radiation analyzer. According to the invention, the electromagnetic field information of the target area is acquired in real time through the electric field probe and the magnetic field probe, the low-frequency bandwidth of the electromagnetic field probe is expanded through the corresponding preamplifiers on the premise of not sacrificing the spatial resolution of the probe, the lowest cut-off frequency reaches 500KHz, the detection requirement of the low-frequency radiation disturbance source of the motor train unit from 1MHz to 30MHz is met, the near-field tracking is gradually carried out on the radiation disturbance source of the motor train unit through a positioning method, and the near-field positioning of the disturbance source is realized.
Description
Technical Field
The invention belongs to the technical field of rail transit, and particularly relates to a near-field positioning system and a near-field positioning method for a radiation disturbance source of a motor train unit.
Background
As an important component of a railway transportation system in China, a motor train unit train becomes the middle-strength force of railway passenger transportation by virtue of a faster speed per hour, but the faster speed per hour also causes the traction current in the motor train unit to be continuously increased, and compared with a large amount of high-frequency disturbance caused by passing neutral phases, the train antenna communication is influenced, the traction disturbance caused by the continuous increase of the traction current of traction equipment is mostly lower than 30MHz low-frequency signals, and compared with high-frequency signals, the generated low-frequency interference signals often have serious influence on a CTCS communication system of the motor train unit train.
The most typical communication device is a communication device BTM of the train, the BTM activates a ground transponder installed on a railway by sending a downlink signal of 27MHz, after the transponder is activated, relevant information such as a driving line and the like is sent into the BTM by an uplink signal of 4.23MHz, and the BTM device demodulates and decodes the information and sends data into ATP to assist the normal operation of the train.
Line crosstalk and rail return can also generate low-frequency disturbances, which can seriously affect the communication of the BTM equipment, except for the traction equipment, and in order to discover the low-frequency disturbances in time. A set of system and a positioning method matched with the system are needed to realize the rapid positioning of the radiation disturbance source of the motor train unit and provide data support for electromagnetic protection.
Disclosure of Invention
The invention aims to solve the technical problem of how to quickly and accurately realize quick positioning of a radiation disturbance source of a motor train unit, and provides a near-field positioning system and a near-field positioning method for the radiation disturbance source of the motor train unit.
The invention is realized in this way, a EMUs radiation disturbance source near field positioning system, this positioning system includes: an electric field probe, a magnetic field probe, a preamplifier, and a portable radiation analyzer, wherein,
the electric field probe is made of a flexible coaxial cable, a part of shielding layer is stripped, an equivalent capacitor is formed by the exposed conductor and the outer shielding layer, and the change of an electric field is induced and a corresponding induced current is generated;
the magnetic field probe is made of a flexible coaxial cable, the cable is bent to form an annular structure, and meanwhile, the shielding layer of the magnetic field cable is cut off at the top end of the magnetic field probe;
the preamplifier comprises a low-input impedance amplifier and a high-input impedance amplifier, wherein the high-impedance gain amplifier is used for expanding the low-frequency characteristic of the electric field probe and is arranged at the output end of the electric field probe, and the low-impedance gain amplifier is used for expanding the low-frequency characteristic of the magnetic field probe and is arranged at the output end of the magnetic field probe;
the portable radiation analyzer collects output signals of the preamplifier, carries out real-time FFT/DFT spectrum analysis on the collected signals, and finds out a radiation disturbance source by combining the electromagnetic field probe to complete the positioning of the radiation disturbance source.
Further, the electric field probe changes size and resolution through the length of the conductor of the bare drain; the magnetic field probe changes size and resolution according to the size of the cross-sectional area of the cable.
Further, the portable radiation analyzer performs discrete Fourier transform or fast discrete Fourier transform on data measured by the electric field probe or the magnetic field probe to obtain a frequency domain curve of the collected voltage signal, and finds out the maximum point of the frequency domain of the voltage signal, wherein the point corresponds to the strongest electric field point or the strongest magnetic field point of the measured object.
A method for positioning a near-field positioning system of a radiation disturbance source by using a positioning system comprises the following steps:
calibrating a low-frequency near-field probe, wherein the low-frequency near-field probe comprises an electric field probe and a magnetic field probe, and an antenna coefficient factor AF of the low-frequency near-field probe is obtained from 500KHz to 30 MHz;
selecting a large-size electric field probe to capture and determine a rough area of a disturbance source, then using a small-size electric field probe to determine the accurate position of the disturbance source, and finding out an area with the maximum electric field radiation intensity of the tested equipment;
selecting a large-size magnetic field probe to capture and determine a rough area of a disturbance source, then using a small-size magnetic field probe to determine the accurate position of the disturbance source, and finding out the area with the maximum magnetic field intensity of the equipment to be detected by using the magnetic field probe;
the portable radiation analyzer is used for obtaining the frequency domain relation of the voltage signal of each point through discrete Fourier transform or fast discrete Fourier transform of data measured by the electric field probe and the magnetic field probe, a frequency domain curve for collecting the voltage signal is formed along with the movement of a measuring range, the maximum point of the voltage signal frequency domain is found out according to the frequency domain curve, and the point corresponds to the strongest electric field point or the strongest magnetic field point of the measured object.
Furthermore, the antenna coefficient factor AF meets the condition that the obtained antenna coefficient factor basically presents flat type change along with the rise of the test frequency within the target frequency range of 500KHz-30MHz, the AF is basically kept unchanged,
wherein V is a voltage and E is an electromagnetic field strength.
Further, the portable radiation analyzer calculates a true electric field value or magnetic field value corresponding to the strongest electric field point or the strongest magnetic field point by using the antenna coefficient factor obtained by verification.
Further, during detection, the electric field probe and the magnetic field probe are attached to the surface of the device to be detected for detection. Compared with the prior art, the invention has the advantages that:
the method can realize accurate positioning of the radiation interference source of the motor train unit, and the whole set of system abandons the traditional devices such as a spectrum analyzer, so that the system volume is greatly reduced, blind spots such as device gaps which are inconvenient to detect by the traditional positioning devices in the past can be detected, the comprehensive investigation of the train radiation interference source is realized, and the quick positioning of the radiation interference source of the motor train unit is quickly and accurately realized.
Drawings
FIG. 1 is a block diagram of a system architecture provided by an embodiment of the present invention;
FIG. 2 is a schematic diagram of a magnetic field probe according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an electric field probe according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, the invention provides a near-field positioning system for a radiation disturbance source of a motor train unit, and the test system comprises: an electric field probe 1, a magnetic field probe 2, a preamplifier 3 and a portable radiation analyzer 4.
The electric field probe is made of a flexible coaxial cable, a part of shielding layer is stripped, an equivalent capacitor is formed by the exposed conductor and the outer shielding layer, and the change of an electric field is induced and a corresponding induced current is generated;
the magnetic field probe is made of a flexible coaxial cable, the cable is bent to form an annular structure, and meanwhile, the shielding layer of the magnetic field cable is cut off at the top end of the magnetic field probe;
the preamplifier comprises a low-input impedance amplifier and a high-input impedance amplifier, wherein the high-impedance gain amplifier is used for expanding the low-frequency characteristic of the electric field probe and is arranged at the output end of the electric field probe, and the low-impedance gain amplifier is used for expanding the low-frequency characteristic of the magnetic field probe and is arranged at the output end of the magnetic field probe;
the portable radiation analyzer collects output signals of the preamplifier, carries out real-time FFT/DFT spectrum analysis on the collected signals, and finds out a radiation disturbance source by combining the electromagnetic field probe to complete the positioning of the radiation disturbance source.
Referring to fig. 3, the electric field probe is made of a flexible coaxial cable, the outer layer of the coaxial cable 11 of the electric field probe is an insulating layer 14, a part of the shield 12 is stripped, an equivalent capacitance is formed by the exposed conductor 13 and the outer shield layer, the change of the electric field is induced and corresponding induced current is generated,
the cable in this embodiment is selected to be RG-58 coaxial cable. Part of the shielding layer is stripped, and an equivalent capacitor is formed by the exposed conductor and the outer shielding layer, so that the change of an electric field is induced and corresponding induced current is generated.
In the present embodiment, for the electric field probe,
wherein the size of C is related to the length of the exposed conductor, the longer the length, the larger the C, which means the sensitivity of the electric field probe is larger (because the fixed Ez, the larger the C, the larger the i, the more easily the abnormality is found), and the sensitivity is inversely proportional to the resolution, the higher the sensitivity, the lower the resolution, the smaller the size of the electric field probe, the smaller the C, the smaller the sensitivity, but the larger the resolution. In the present embodiment, the large size and the small size refer to the length of the small-sized bare conductor which is at least about 2 times the length of the large-sized bare conductor.
Referring to fig. 2, the magnetic field probe is also made of a flexible coaxial cable, and is made of a flexible coaxial cable 21, the outer layer of the flexible coaxial cable is a rubber insulating layer 22, the flexible coaxial cable is bent to form an annular structure, and meanwhile, a shielding layer of the magnetic field cable is cut off at the top end of the magnetic field probe to form an exposed arc-shaped section 23. The cable is bent to form an annular structure, and meanwhile, the shielding layer of the cable is cut off at the top end of the probe, so that the probe is ensured to shield the influence caused by an electric field.
In order to conveniently and accurately find a magnetic field signal disturbance source, a plurality of groups of magnetic field probes with different sizes are designed in the embodiment, and the annular diameter of each probe is from 1cm to 30cm, so that the requirement of a system positioning method is met. Magnetic field probe
Wherein S is the loop area, and the larger S is, the larger V is, and at this time, the sensitivity of the magnetic field probe is high, but the resolution is low. In this embodiment, the large dimension is at least two times larger than the small dimension of the ring diameter.
The pre-amplifier in this embodiment is divided into two types, which are a low input impedance amplifier and a high input impedance amplifier, respectively, wherein the high impedance gain amplifier is an in-phase proportional amplifier circuit, and an OPA656 chip is adopted to implement the circuit design. The low-impedance gain amplifier is a transimpedance amplification circuit, an AD8015 chip is adopted to realize circuit design, the cut-off frequency of the near-field probe is effectively reduced through the design of the preamplifier, meanwhile, the sensitivity of the probe is improved, and the accurate detection of low-frequency signals is guaranteed.
The portable radiation analyzer collects low-frequency output signals of the amplifier, conducts real-time FFT/DFT spectrum analysis on the collected signals, and combines the electromagnetic field probe to find out a radiation disturbance source to complete positioning of the radiation disturbance source.
A test method for performing the detection positioning test by using the system is provided:
calibrating a low-frequency near-field probe, wherein the low-frequency near-field probe comprises an electric field probe and a magnetic field probe, and an antenna coefficient factor AF of the low-frequency near-field probe is obtained from 500KHz to 30 MHz;
selecting a large-size electric field probe to capture and determine an approximate area of a disturbance source, then using the small-size electric field probe to determine the accurate position of the disturbance source, and finding out the area with the maximum electric field radiation intensity of the tested equipment;
selecting a large-size magnetic field probe to capture and determine an approximate area of a disturbance source, then using the small-size magnetic field probe to determine the accurate position of the disturbance source, and finding the area with the maximum magnetic field intensity of the equipment to be detected by using the magnetic field probe;
the portable radiation analyzer is used for obtaining the frequency domain relation of the voltage signal of each point through discrete Fourier transform or fast discrete Fourier transform of data measured by the electric field probe and the magnetic field probe, a frequency domain curve for collecting the voltage signal is formed along with the movement of a measuring range, the maximum point of the voltage signal frequency domain is found out according to the frequency domain curve, and the point corresponds to the strongest electric field point or the strongest magnetic field point of the measured object.
Wherein, the calibration of the low-frequency near-field probe is carried out; with reference to the electromagnetic compatibility standard, obtaining an antenna coefficient factor AF of 500KHz-30MHz of the low-frequency near-field probe through a 50 omega microstrip line test, determining the corresponding relation between the obtained voltage V and the electromagnetic field intensity E (H),
within the target frequency range of 500KHz-30MHz, the obtained antenna coefficient factor basically shows flat type change along with the rise of the test frequency, and AF is basically kept unchanged. Basically, the linear change between the input electromagnetic field intensity and the output voltage of the test probe in the target frequency is met, and the accuracy and the reliability of the result of the subsequent test are ensured.
When actual detection is carried out, a near-field probe with larger size and higher sensitivity is selected to execute EMI test, an approximate area of a disturbance source is captured and determined, and then the probe with smaller size and higher resolution is used for determining the accurate position of the disturbance source. In order to reduce the influence of the distance on the detection effect, the probe is required to be attached to the surface of the device to be detected for detection during detection.
Wherein, utilizing portable radiation analyzer to carry out real-time data analysis includes: and obtaining a frequency domain curve of the collected voltage signal through DFT (discrete Fourier transform) or FFT (fast discrete Fourier transform), and finding out the maximum point of the voltage signal frequency domain. This point corresponds to the strongest electric field point (magnetic field point) of the measured article. Meanwhile, the real electric field (magnetic field) value of the point can be calculated through the antenna coefficient factor obtained by the previous verification.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (7)
1. The utility model provides a EMUs radiation disturbance source near field positioning system which characterized in that, this positioning system includes: an electric field probe, a magnetic field probe, a preamplifier, and a portable radiation analyzer, wherein,
the electric field probe is made of a flexible coaxial cable, a part of shielding layer is stripped, an equivalent capacitor is formed by the exposed conductor and the outer shielding layer, and the change of an electric field is induced and corresponding induced current is generated;
the magnetic field probe is made of a flexible coaxial cable, the cable is bent to form an annular structure, and meanwhile, the shielding layer of the magnetic field cable is cut off at the top end of the magnetic field probe;
the preamplifier comprises a low-input impedance amplifier and a high-input impedance amplifier, wherein the high-impedance gain amplifier is used for expanding the low-frequency characteristic of the electric field probe and is arranged at the output end of the electric field probe, and the low-impedance gain amplifier is used for expanding the low-frequency characteristic of the magnetic field probe and is arranged at the output end of the magnetic field probe;
the portable radiation analyzer collects output signals of the preamplifier, carries out real-time FFT/DFT spectrum analysis on the collected signals, and finds out a radiation disturbance source by combining the electromagnetic field probe to complete the positioning of the radiation disturbance source.
2. The near field positioning system of the radiation disturbance source of the motor train unit according to claim 1,
the size and the resolution of the electric field probe are changed through the length of the conductor with the bare leakage; the magnetic field probe changes size and resolution according to the size of the cross-sectional area of the cable.
3. The near field positioning system for the radiation disturbance source of the motor train unit according to claim 1, wherein the portable radiation analyzer performs discrete Fourier transform or fast discrete Fourier transform on data measured by the electric field probe or the magnetic field probe to obtain a frequency domain curve of an acquired voltage signal, and finds out a maximum point of a frequency domain of the voltage signal, wherein the maximum point corresponds to a strongest electric field point or a strongest magnetic field point of a measured object.
4. A method for positioning a near-field positioning system of a radiation disturbance source by using the positioning system of any one of claims 1 to 3, characterized by comprising the steps of:
calibrating a low-frequency near-field probe, wherein the low-frequency near-field probe comprises an electric field probe and a magnetic field probe, and an antenna coefficient factor AF of the low-frequency near-field probe is obtained from 500KHz to 30 MHz;
selecting a large-size electric field probe to capture and determine an approximate area of a disturbance source, then using the small-size electric field probe to determine the accurate position of the disturbance source, and finding out the area with the maximum electric field radiation intensity of the tested equipment;
selecting a large-size magnetic field probe to capture and determine an approximate area of a disturbance source, then using the small-size magnetic field probe to determine the accurate position of the disturbance source, and finding the area with the maximum magnetic field intensity of the equipment to be detected by using the magnetic field probe;
the portable radiation analyzer is used for obtaining the frequency domain relation of the voltage signal of each point through discrete Fourier transform or fast discrete Fourier transform of data measured by the electric field probe and the magnetic field probe, a frequency domain curve for collecting the voltage signal is formed along with the movement of a measuring range, the maximum point of the voltage signal frequency domain is found out according to the frequency domain curve, and the point corresponds to the strongest electric field point or the strongest magnetic field point of the measured object.
5. The positioning method according to claim 4, wherein the antenna coefficient factor AF satisfies that within a target frequency range of 500KHz-30MHz, the obtained antenna coefficient factor exhibits a substantially flat variation with an increase in test frequency, AF remains substantially constant,
wherein V is a voltage and E is an electromagnetic field strength.
6. The positioning method according to claim 4,
and the portable radiation analyzer calculates the real electric field value or magnetic field value corresponding to the strongest electric field point or the strongest magnetic field point by using the antenna coefficient factor obtained by verification.
7. The positioning method according to claim 4, wherein the electric field probe and the magnetic field probe are attached to the surface of the device under test for probing.
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| CN202210974104.7A CN115356562A (en) | 2022-08-15 | 2022-08-15 | Near-field positioning system and method for radiation disturbance source of motor train unit |
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| CN202210974104.7A CN115356562A (en) | 2022-08-15 | 2022-08-15 | Near-field positioning system and method for radiation disturbance source of motor train unit |
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