CN114609941A - Rail train cable detection device - Google Patents

Abstract

The invention relates to a rail train cable detection device, which comprises a lithium battery, a charging management circuit and a power management circuit which are respectively connected with a TDR detection circuit, a DDS detection circuit, a direct current resistance detection circuit, a wiring diagram test circuit and a serial communication circuit. The multifunctional highly-integrated rail train cable detection device has the advantages that functional circuits are independent and do not influence each other, the one-key detection function is realized, the time cost and the management cost of cable troubleshooting are greatly reduced, and the working efficiency is greatly improved.

Description

Rail train cable detection device

Technical Field

The invention relates to the field of twisted pair detection, in particular to a rail train cable detection device.

Background

Modern urban rail train communication networks are mainly based on shielding twisted pair cables, so troubleshooting of train communication cables becomes one of the core technologies of modern train control systems. At present, troubleshooting and maintenance measures for train communication cables are still at a very crude level in most railway train production enterprises in China and in most urban railway train vehicle sections. Generally, only a conventional digital multimeter is adopted to perform on-off detection on a cable, so that the connection of the cable cannot be diagnosed, accurate positioning and troubleshooting of a fault point cannot be realized, or a specific fault reason cannot be found out. In the face of cable faults, only a rough processing mode of replacing the whole section of cable can be adopted, so that the maintenance cost is high, and the working efficiency is low. There are also related general type twisted-pair cable detection devices in the market, taking DSX8000 and DSX5000 line optical cable certification test devices of the FLUKE brand as examples, the test devices of this type are leading products in the current market, and are mainly used for the certification test of shielding twisted-pair cables and optical cables, and have the troubleshooting function of optical cables at the same time. However, in an application scenario of troubleshooting of a rail train cable, actual operation is inconvenient, an adapter plug needs to be additionally customized in the use process, a calibration test needs to be performed before each measurement, actual application index performance is redundant, imported equipment is high in price, and the requirement for line maintenance and mass assembly cannot be met.

Disclosure of Invention

Aiming at the existing simple and crude detection means and the condition that the existing products in the market are not suitable, the embodiment of the invention aims to provide the detection device which has comprehensive detection function, simple and convenient operation and reasonable price, and the performance index meets the detection requirement.

In order to achieve the above object, the embodiments of the present invention provide the following technical solutions:

the utility model provides a rail train cable detection device, includes lithium cell, charge management circuit, power management circuit and is connected with TDR detection circuitry, DDS detection circuitry, direct current resistance detection circuitry, wiring diagram test circuit, serial communication circuit respectively, and each functional circuit integrates on same circuit board, its characterized in that:

the TDR detection circuit includes: the circuit comprises a narrow pulse signal generation circuit, a narrow pulse signal single-end to differential conversion circuit, a current type feedback differential amplification circuit, a narrow pulse reflection signal attenuation circuit, a narrow pulse reflection signal adjustable gain differential amplification circuit and a 500MSPS analog-to-digital conversion circuit;

the DDS detection circuit includes: DDS signal generation, low-pass filtering, radio frequency amplification, directional coupling transmission, radio frequency transformer isolation transmission, logarithmic detector power-voltage conversion and analog-to-digital conversion;

the direct current resistance detection circuit includes: the circuit comprises a constant voltage source, a resistance bridge circuit, a differential amplification circuit, a voltage division circuit and an analog-to-digital converter;

the wiring diagram test circuit includes: a digital-to-analog conversion circuit and an analog-to-digital conversion circuit;

the narrow pulse signal width is adjustable, the minimum width is 4ns, and the rising edge signal is less than 1 ns;

the gain multiple of the narrow pulse reflected signal is adjustable, and the maximum gain is 26 dB;

the bandwidth of a sweep frequency signal generated by the DDS is more than 100 MHz;

the minimum signal frequency of the logarithmic detector is 1 MHz;

each function detection circuit is switched to be connected with the cable hanging port through a relay network, the relay network adopts a tree-shaped connection structure, one function circuit is connected in the actual measurement process, and the connection of other function circuits is cut off at the same time.

Preferably, in the scheme, an ARM + FPGA framework is adopted, the ARM mainly realizes man-machine interaction, the FPGA collects the measurement data of each functional circuit through an analog-to-digital converter, and the ARM and the FPGA exchange data through an EMIFA interface.

In the above aspect, a GUI is preferably further provided for displaying the measurement data.

In the above scheme, preferably, ADC08500 chip design is adopted for analog-to-digital conversion.

In the above-mentioned scheme, preferably, DB9 joint is adopted to carry out the hitching of the cable to be tested.

In the scheme, the BQ24133 chip design is preferably adopted to carry out lithium battery charging management.

In the above scheme, it is preferable that the AD9852 chip design is adopted to perform direct digital frequency synthesis to generate the radio frequency signal.

In the above scheme, preferably, a dual-computer pairing detection working mode is adopted to perform dual-computer synchronous measurement data lookup.

Preferably, in the above scheme, a relay network design mode is adopted to perform connection switching of the multifunctional detection circuit.

The invention has the beneficial effects that: the instrument functions required by troubleshooting of the vehicle-mounted cable of the rail train are highly integrated on the same circuit board, the vehicle-mounted cable is directly butted through a special interface to carry out fault location and measurement of relevant performance indexes, various measured data results are observed through a GUI (graphical user interface), and meanwhile, a double-machine observation mode is adopted, so that the control flow is simplified to a great extent, the localization of special equipment is realized, and the price cost of the special equipment is greatly reduced.

Drawings

Fig. 1 is a schematic structural diagram of a rail train cable detection device according to the present invention.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

Fig. 1 shows a rail train cable detection device, which integrates multiple functions of TDR diagnostic test, DDS test, dc resistance test, wiring diagram test, differential serial communication, and the like on the same circuit board in a circuit design manner. An ARM + FPGA framework is adopted, the ARM mainly realizes man-machine interaction, the FPGA collects the measurement data of each functional module through an analog-to-digital converter, the data exchange is carried out between the ARM and the FPGA through an EMIFA interface, and the measurement data are displayed through a GUI.

And TDR diagnosis test, namely diagnosing a fault point connected with a cable by using the characteristic of a narrow pulse reflection signal, detecting the length of the cable, and testing the transmission time delay of the cable. The diagnosis fault types comprise open circuit, short circuit and poor connection. The single-ended narrow pulse signal is output through an FPGA pin by adopting a 250MHz frequency clock signal for driving, the pulse width is adjustable, and the minimum width is 4ns (related to the driving clock frequency). The single-side narrow pulse signal is amplified through a current type feedback differential circuit, the amplitude of the narrow pulse signal is further adjusted through two-stage shaping, then the TDR diagnostic circuit is connected to a tested cable through a relay network in a hanging mode, and the adjusted narrow pulse signal is transmitted along the tested cable to generate a narrow pulse reflection signal. The narrow pulse reflection signal is input after being subjected to differential emission, the resistor attenuation network and then the narrow pulse reflection signal are input to an analog-to-digital converter ADC08500 through a programmable current type feedback differential amplifier. And then, the FPGA processing system acquires waveform data of the narrow pulse reflection signal and transmits the data to the ARM system through the EMIFA interface.

And in the DDS test, the transmission performance of the cable, including return loss, insertion loss and characteristic impedance, is evaluated by using the radio-frequency signal generated by the DDS chip according to a time domain reflection technology, and the degree of the good performance of the transmission signal of the cable is detected and evaluated. The DDS chip AD9852 can generate 1 MHz-150 MHz sine wave signals, and the step frequency is less than 1 Hz. The radio frequency signal is subjected to low-pass filtering attenuation processing to eliminate interference and harmonic waves, then passes through a blocking capacitor and is subjected to radio frequency amplification, the amplitude of the radio frequency signal is adjusted, an incoming signal and a reflected signal are separated through a directional coupler, an incident signal and a reflected signal on a coupling side are respectively sent to a logarithmic detector to be subjected to power voltage conversion, the incident signal on a transmission path is subjected to linear isolation through a radio frequency transformer and is switched and connected to a cable to be measured through a relay network. After the power voltage of the logarithmic detector is converted, the power voltage of the incident signal and the power voltage of the reflected signal can be obtained, the voltage values of the incident signal and the reflected signal are acquired by adopting an analog-to-digital converter, and the signal power of the incident signal and the reflected signal is calculated through conversion of a corresponding formula, so that a related performance measurement value is obtained through measurement.

And D, testing the direct current resistance, namely, adopting a resistance bridge testing principle to short-circuit the far ends of 1 group of line pairs of the tested cable access test, accessing the far ends into a resistance bridge arm through a relay network, wherein the voltage balance of the arm at two sides of the resistance bridge changes, and measuring to obtain the direct current resistance value of the tested cable by monitoring the changed voltage.

The wiring diagram test adopts a preset voltage measurement method, generates direct current voltage by using a digital-to-analog conversion circuit, loads the direct current voltage to one end of a tested line pair, performs analog-to-digital conversion and acquisition on the corresponding line pair at the opposite end, and then compares the loaded preset voltage with the detection voltage so as to judge the correctness of a connection line sequence.

The serial communication in a differential form is used for information interaction between the host and the remote equipment by means of the tested cable in the test process.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (9)

1. A rail train cable detection device, comprising: the cable connection port, the charging management circuit are connected with the lithium battery, the charging management circuit is connected with the power management circuit, the lithium battery is connected with the power management circuit, the power management circuit is respectively connected with the TDR detection circuit, the DDS detection circuit, the direct-current resistance detection circuit, the wiring diagram test circuit and the serial communication circuit, and all the functional circuits are integrated on the same circuit board.

2. The rail train cable detection device as claimed in claim 1, wherein an ARM + FPGA framework is adopted, the ARM mainly realizes man-machine interaction, the FPGA collects measurement data of each functional module through an analog-to-digital converter, and data exchange is performed between the ARM and the FPGA through an EMIFA interface.

3. The rail train cable detection device of claim 2, wherein a GUI is further provided for displaying the measurement data.

4. The rail train cable detection device of claim 2, wherein the ADC08500 chip design is used for analog-to-digital conversion.

5. The rail train cable inspection device of claim 1, wherein the cable to be inspected is hooked by using a DB9 connector.

6. The rail train cable detection device of claim 1, wherein a BQ24133 chip design is adopted for lithium battery charging management.

7. The rail train cable detection device of claim 1, wherein the radio frequency signal is generated by direct digital frequency synthesis using an AD9852 chip design.

8. The rail train cable detection device as claimed in claim 1, wherein a dual-machine pairing detection mode is adopted to perform dual-machine synchronous measurement data lookup.

9. The rail train cable detection device according to claim 1, wherein a relay network design is adopted to perform connection switching of the multifunctional detection circuit.

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