Cable detection method and device

Abstract

The present disclosure relates to the field of cable detection technology and provides a cable detection method and device, including: repeatedly sending spread spectrum signals with different parameter settings to one end of the cable under test, and simultaneously receiving a reflected signal at the same end of the cable under test; after each reflected signal is obtained, converting the reflected signal into a first cable model curve through a spread spectrum signal receiving algorithm; comparing the first cable model curve with a reference model curve Crf to obtain a comparison difference; the reference model curve Crf is a cable model curve when the cable is set to be free of damage; if the comparison difference cannot be zero, it is determined that the cable is damaged; based on the obtained cable model curve, the terminal position, damage position, and cable aging degree of the damaged cable are calculated. The present invention can solve the problems of limited detection, equipment impact, and poor accuracy in existing rail transit cable detection technologies.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of cable detection, and in particular to a cable detection method and device. Background Art

[0002] Cables are the carriers of signal transmission, and their health is crucial to signal transmission quality. As cables age over time, they need to be assessed and maintained promptly. When a cable breaks, the location of the break must be determined to facilitate appropriate repairs.

[0003] Existing rail transit cable detection technology has the following limitations:

[0004] 1) Optical inspection: Cables are imaged using X-rays and other methods, and the aging condition is visually determined based on experience. The disadvantage is that the cables must be exposed, making them unsuitable for buried cables or cables hidden in vehicle bodies.

[0005] 2) Current signal inspection: By sending a current signal at one end and receiving it at the other end, the signal characteristics are determined to reflect the cable parameters. The disadvantage is that both the receiving and transmitting ends must be tested simultaneously, which is not suitable for long-distance cables.

[0006] 3) Hi-voltage test: By injecting a high-voltage signal, the insulation performance is checked to determine the cable condition. The disadvantage is that the high-voltage signal can damage connected equipment and affect the working signal. It requires power off for inspection and may cause complete damage to aging cables.

[0007] 4) Impedance and other electrical characteristic parameters are checked by injecting special signals to test the cable impedance and other electrical characteristic parameters. The disadvantage is that it requires only cable testing and the cable cannot be connected to external devices, otherwise the parameters will be distorted.

[0008] 5) Environmental parameter prediction: This method estimates the cable aging time based on external conditions such as vibration, electromagnetic field, temperature, and corrosion. However, this method is only probabilistic and cannot provide definitive conclusions for individual cables. Summary of the Invention

[0009] To address these issues, the present disclosure provides a cable detection method and device. This method inputs a spread-spectrum signal to one end of the cable under test and receives a reflected signal at the same end. Signal parameters are then modified to obtain multiple reflected signals. This signal is then processed by an algorithm to generate a cable model curve. The numerical value of this cable model curve is then used to perform cable detection. This method addresses the limitations of existing rail transit cable detection technologies, including detection limitations, equipment impact, and poor accuracy.

[0010] The following are technical details of the present invention:

[0011] A cable detection method, comprising:

[0012] Repeatedly send spread spectrum signals with different parameter settings to one end of the cable under test, and simultaneously receive the reflected signal at the same end of the cable under test;

[0013] After each reflection signal is obtained, the reflection signal is converted into a first cable model curve through a spread spectrum signal receiving algorithm;

[0014] Comparing the first cable model curve with the reference model curve Crf to obtain a comparison difference; the reference model curve Crf is a cable model curve when the cable is set to be free of damage; if the comparison difference cannot be zero, it is determined that the cable is damaged;

[0015] Based on the obtained cable model curve, the terminal position, damage position and cable aging degree of the damaged cable are calculated.

[0016] Further,

[0017] The method of repeatedly sending spread spectrum signals with different parameter settings to one end of the cable under test comprises:

[0018] Adjusting and changing the parameter settings of the spread spectrum signal based on the difference between the first cable model curve and the reference model curve Crf so that the difference between the cable model curve obtained next time and the reference model curve Crf is smaller than the previous difference;

[0019] If the difference between the cable model curve and the reference model curve Crf cannot be zero, after M cable model curves are obtained, the transmission of the spread spectrum signal to the same end of the tested cable is stopped; M is the number threshold.

[0020] Further,

[0021] The terminal position, damage position, and cable aging degree of the damaged cable are calculated based on the obtained cable model curve; including:

[0022] Select the 2nd to Mth cable model curves C2...C among the M cable model curves. m , apply the decision algorithm to screen the 2nd to Mth cable model curves C2...C m In the figure, the cable model curve with the terminal peak value lower than the threshold value;

[0023] The filtered cable model curves are merged into the final cable model curve Cout using a fusion algorithm;

[0024] The final cable model curve Cout is used to calculate the terminal position, damage position, and cable aging degree of the damaged cable.

[0025] Further,

[0026] The method of calculating the terminal position, damage position, and aging degree of the damaged cable using the final cable model curve Cout includes:

[0027] The terminal position of the cable is: the highest peak position of Cout × the propagation factor of the tested cable under different parameter signals;

[0028] The damage location of the cable is: the other small peak location of Cout × the propagation factor of the tested cable under different parameter signals;

[0029] The cable aging degree Ac is:

[0030] Ac=Yc×K2

[0031] Wherein, Ac=Yc×K2, K2 is a preset aging correction factor, and Yc is the average or maximum value of the peak amplitudes of other small peaks of Cout.

[0032] Further,

[0033] Each time a reflected signal is received at the same end of the tested cable, a filtering algorithm is applied to filter out the initial reflected signal, and then the reflected signal is converted into a first cable model curve using a spread spectrum signal receiving algorithm.

[0034] Further,

[0035] The filtering algorithm is: using coherent demodulation to extract a specific delayed signal.

[0036] Further,

[0037] The parameters of the spread spectrum signal include:

[0038] Carrier frequency fi, pseudo spreading code frequency fcn, pseudo spreading code pattern Dn, pseudo spreading code length Ln; where n is a natural number from 1 to N, and N is the number of pseudo spreading code groups.

[0039] A cable detection device, used to perform the cable detection method, characterized by comprising:

[0040] A signal sending module, used for repeatedly sending spread spectrum signals with different parameter settings to one end of the cable under test;

[0041] A signal receiving module is used to simultaneously receive reflected signals at the same end of the cable under test;

[0042] a signal analysis module configured to convert the reflected signal into a first cable model curve using a spread spectrum signal receiving algorithm each time the reflected signal is obtained, and compare the first cable model curve with a reference model curve Crf to obtain a comparison difference; the reference model curve Crf is a cable model curve when the cable is assumed to be free of damage;

[0043] If the comparison difference cannot be zero, it is determined that the cable is damaged;

[0044] Based on the obtained cable model curve, the terminal position, damage position and cable aging degree of the damaged cable are calculated.

[0045] Further,

[0046] It also includes: a signal generation module for generating a standard test vector;

[0047] The signal sending module converts the standard test vector into an analog signal Sa1, and outputs the analog signal Sa1 as a spread spectrum signal to one end of the cable under test.

[0048] Further,

[0049] When the cable under test is not disconnected from the external device:

[0050] The signal analysis module also adjusts the test parameters according to the analysis results, and outputs the new test parameters to the signal generation module through feedback information, so that the signal generation module adjusts the test vector according to the new parameters and performs a new round of testing;

[0051] The signal analysis module obtains a model curve of the final cable aging state according to the results of multiple rounds of testing and a comparison algorithm.

[0052] Compared with the prior art, the present disclosure has the following advantages:

[0053] This method uses single-ended testing, which requires only sending a spread spectrum signal at one end of the cable and receiving the reflected signal. It does not require exposing the entire cable and is not limited by cable length or whether it is connected to external devices, greatly expanding the scope of application of the test. Furthermore, because the spread spectrum signal power of this method is low, it will not affect the normal operation of the equipment or cause damage to the cable, thus avoiding adverse effects on the equipment and cable caused by the test.

[0054] Secondly, this method changes the parameters of the spread spectrum signal multiple times. Signals with different parameters propagate and reflect differently in the cable, which can fully reflect the cable characteristics. After receiving the reflected signal, the spread spectrum signal reception algorithm is used to convert the reflected signal into a cable model curve, which is then compared with the reference model curve to determine whether the cable is damaged. The terminal position, damage location and aging degree are calculated based on the cable model curve, making the detection results more accurate and able to provide accurate assessments for individual cables.

[0055] Other features and advantages of the present disclosure will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present disclosure. The purposes and other advantages of the present disclosure can be realized and obtained by the structures indicated in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0057] Figure 1 Shown is a schematic diagram of the method of the present invention;

[0058] Figure 2 Shown is a schematic diagram of the device of the present invention. DETAILED DESCRIPTION

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present disclosure without making any creative efforts shall fall within the scope of protection of the present disclosure.

[0060] In order to solve the problem, the present invention proposes the following technical solutions to solve the technical problem:

[0061] A cable detection method, such as Figure 1 Shown, including:

[0062] 1. Test:

[0063] Outputting the spread spectrum analog signal Sa1 to one end of the cable under test;

[0064] At the same end of the cable under test, the analog signal Ra1 is received and converted into a reception vector Rd1 in digital format simultaneously with the transmission;

[0065] Apply filtering algorithm to filter out the initial reflection signal;

[0066] Applying the spread spectrum signal receiving algorithm, Rd1 is analyzed to obtain the first cable model curve C1;

[0067] Adjust the signal parameters of the spread spectrum signal multiple times and input it into one end of the tested cable to obtain multiple cable model curves C2...C m (Parameter selection, according to the parameters of the tested cable and the test results, select different parameter adjustment methods. For example, adjust the signal frequency, adjust the code type, adjust the signal power)

[0068] Specifically, the generation of the analog signal Sa1 includes:

[0069] Generate a digital test vector using the initial default parameter set. (The parameter set includes the spread spectrum signal's carrier frequency fi, pseudo spreading code frequency fcn, pseudo spreading code pattern Dn, and pseudo spreading code length Ln, where n is a natural number and its maximum value, N, represents a signal containing N sets of pseudo spreading codes with different parameters.)

[0070] The first group of digitized test vectors Sd1 is converted into analog signals Sa1.

[0071] 2. Signal processing:

[0072] Set the reference curve to the reference model curve Crf, where the reference model curve Crf is the cable model curve when the cable is set to be free of damage.

[0073] Compare the first cable model curve C1 (first cable model curve) with the reference model curve C rf Perform comparisons to obtain comparison differences;

[0074] Adjusting and changing the parameter settings of the spread spectrum signal based on the difference between the first cable model curve C1 and the reference model curve Crf so that the difference between the cable model curve obtained next time and the reference model curve Crf is smaller than the previous difference;

[0075] If the difference between the cable model curve and the reference model curve Crf is 0, it means that the cable is not damaged and there is no need to detect the cable terminal position, damage position, and cable aging degree.

[0076] If the difference between the cable model curve and the reference model curve Crf is always not zero and cannot be zero, M cable model curves C2...C m After that, stop sending spread spectrum signals with different parameter settings to the same end of the cable under test.

[0077] Compare C2...C m The terminal peaks V2, ..., VM, apply the decision algorithm to delete C2...C m Among the curves with too low terminal peak values, a fusion algorithm is applied to the remaining curves to merge multiple curves into the same curve, which is recorded as Cout.

[0078] 3. Detection and analysis:

[0079] The location of the cable terminal can be determined based on the highest peak value of Cout. The location of cable damage can be determined based on the locations of other small peak values of Cout.

[0080] The terminal position of the cable is: the highest peak position of Cout × the propagation factor of the tested cable under different parameter signals;

[0081] The damage location of the cable is: the other small peak location of Cout × the propagation factor of the tested cable under different parameter signals;

[0082] The cable terminal position or cable damage position is Pc, and the Cout peak position or other small peak position is Tc. The relationship between Pc and Tc is:

[0083] Pc=Tc×K1

[0084] Among them, K1 represents the propagation factor of cables of different materials under different parameter signals.

[0085] Calculate the cable aging degree Ac based on the peak amplitude Yc of other small peaks of Cout;

[0086] Wherein, Ac=Yc×K2, K2 is a preset aging correction factor, and Yc is the average or maximum value of the peak amplitudes of other small peaks of Cout.

[0087] The present invention determines the terminal and damage locations based on the relationship between the signal propagation speed in the cable (represented by the propagation factor K1) and the time delay of the reflected signal (the peak position of the curve);

[0088] The changes in electrical performance caused by cable aging are reflected in the amplitude of the reflected signal. The aging degree is calculated by establishing a quantitative relationship between the small peak amplitude Yc and the aging degree through the preset aging correction factor K2, overcoming the shortcomings of traditional detection technology.

[0089] Specifically,

[0090] 1) There are many types of pseudo-spreading codes, a typical example being the M sequence. The choice of polynomial can be arbitrary.

[0091] 2) There are many types of filtering algorithms, a typical example is: coherent demodulation to extract specific delayed signals.

[0092] 3. There are many types of spread spectrum signal reception algorithms, a typical example being correlation operations.

[0093] 4. There are many types of decision algorithms. Typical examples include: using a preset threshold as the decision threshold; or taking the median of each value as the decision threshold.

[0094] 5. There are many types of fusion algorithms, a typical example is: superposition of multiple curves.

[0095] 6. The propagation factor K1 and the aging correction factor K2 are calculated based on a large amount of measured data combined with theoretical analysis. There are various types of quantization algorithms, typical examples of which include expert scoring and normalization relative to peak values.

[0096] The present invention has the following effects:

[0097] 1. Compared with the existing optical inspection solution, the solution of the present invention does not need to expose the cable. It only needs to expose one end of the cable connector. There is no construction requirement, which saves costs.

[0098] 2. Compared with the existing current signal inspection scheme, it only needs to test at one end of the cable, does not require outdoor long-distance operation, and does not involve the coordination of simultaneous operation at both ends. It is easier to implement and avoids the impact of synchronization errors caused by long-distance operation.

[0099] 3. Compared with the existing withstand voltage inspection scheme, the injection signal power of the present invention is low, which does not affect the operation of the equipment and does not damage the cable.

[0100] 4. Comparative impedance and other electrical characteristic parameters are checked. Through multiple sets of signal iterative tests, the curve with the least impact is selected, eliminating the influence of terminal connection equipment on signal reflection. It is not required to cut off external connections, which is conducive to maintaining the connection of existing equipment on site and reducing the possible impact of construction on safety.

[0101] 5. By comparing the predictions of environmental parameters, an evaluation curve can be given for each individual with high accuracy and strong pertinence.

[0102] Based on the method of the present invention, the embodiment of the present disclosure also provides a device for executing the above method, such as Figure 2 Shown, including:

[0103] A signal sending module, used for repeatedly sending spread spectrum signals with different parameter settings to one end of the cable under test;

[0104] A signal receiving module is used to simultaneously receive reflected signals at the same end of the cable under test;

[0105] a signal analysis module configured to convert the reflected signal into a first cable model curve using a spread spectrum signal receiving algorithm each time the reflected signal is obtained, and compare the first cable model curve with a reference model curve Crf to obtain a comparison difference; the reference model curve Crf is a cable model curve when the cable is assumed to be free of damage;

[0106] If the comparison difference cannot be zero, it is determined that the cable is damaged;

[0107] Based on the obtained cable model curve, the terminal position, damage position and cable aging degree of the damaged cable are calculated.

[0108] While the cable is connected to the external device, the signal analysis module adjusts the test parameters based on the analysis algorithm and outputs the new parameters to the signal generation module via feedback. The signal generation module then adjusts the test vector based on the new parameters and performs a new round of testing. Based on the results of multiple rounds of testing and a comparison algorithm, the signal analysis module generates a final model curve for the cable's aging status.

[0109] Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A cable detection method, characterized in that: include: Repeatedly send spread spectrum signals with different parameter settings to one end of the cable under test, and simultaneously receive the reflected signal at the same end of the cable under test; After each reflection signal is obtained, the reflection signal is converted into a first cable model curve through a spread spectrum signal receiving algorithm; Comparing the first cable model curve with the reference model curve Crf to obtain a comparison difference; the reference model curve Crf is a cable model curve when the cable is set to be free of damage; if the comparison difference cannot be zero, it is determined that the cable is damaged; Based on the obtained cable model curve, the terminal position, damage position and cable aging degree of the damaged cable are calculated; The method of repeatedly sending spread spectrum signals with different parameter settings to one end of the cable under test comprises: Adjusting and changing the parameter settings of the spread spectrum signal based on the difference between the first cable model curve and the reference model curve Crf so that the difference between the cable model curve obtained next time and the reference model curve Crf is smaller than the previous difference; If the difference between the cable model curve and the reference model curve Crf cannot be zero, after M cable model curves are obtained, the transmission of the spread spectrum signal to the same end of the tested cable is stopped; M is the number threshold.

2. A cable detection method according to claim 1, characterized in that: The terminal position, damage position, and cable aging degree of the damaged cable are calculated based on the obtained cable model curve; including: Select the 2nd to Mth cable model curves C2...C among the M cable model curves. m , apply the decision algorithm to screen the 2nd to Mth cable model curves C2...C m In the figure, the cable model curve with the terminal peak value lower than the threshold value; The filtered cable model curves are merged into the final cable model curve Cout using a fusion algorithm; The final cable model curve Cout is used to calculate the terminal position, damage position, and cable aging degree of the damaged cable.

3. A cable detection method according to claim 2, characterized in that: The method of calculating the terminal position, damage position, and aging degree of the damaged cable using the final cable model curve Cout includes: The terminal position of the cable is: the highest peak position of Cout × the propagation factor of the tested cable under different parameter signals; The damage location of the cable is: the other small peak location of Cout × the propagation factor of the tested cable under different parameter signals; The cable aging degree Ac is: Ac=Yc×K2 Wherein, Ac=Yc×K2, K2 is a preset aging correction factor, and Yc is the average or maximum value of the peak amplitudes of other small peaks of Cout.

4. A cable detection method according to claim 1, characterized in that: Each time a reflected signal is received at the same end of the tested cable, a filtering algorithm is applied to filter out the initial reflected signal, and then the reflected signal is converted into a first cable model curve using a spread spectrum signal receiving algorithm.

5. A cable detection method according to claim 4, characterized in that: The filtering algorithm is: using coherent demodulation to extract a specific delayed signal.

6. A cable detection method according to claim 1, characterized in that: The parameters of the spread spectrum signal include: Carrier frequency fi, pseudo spreading code frequency fcn, pseudo spreading code pattern Dn, pseudo spreading code length Ln; where n is a natural number from 1 to N, and N is the number of pseudo spreading code groups.

7. A cable detection device, used to perform the method according to claim 1, characterized in that: include: A signal sending module, used for repeatedly sending spread spectrum signals with different parameter settings to one end of the cable under test; A signal receiving module is used to simultaneously receive reflected signals at the same end of the cable under test; a signal analysis module configured to convert the reflected signal into a first cable model curve using a spread spectrum signal receiving algorithm each time the reflected signal is obtained, and compare the first cable model curve with a reference model curve Crf to obtain a comparison difference; the reference model curve Crf is a cable model curve when the cable is assumed to be free of damage; If the comparison difference cannot be zero, it is determined that the cable is damaged; Based on the obtained cable model curve, the terminal position, damage position and cable aging degree of the damaged cable are calculated.

8. A cable detection device according to claim 7, characterized in that: Also includes: A signal generation module, used for generating standard test vectors; The signal sending module converts the standard test vector into an analog signal Sa1, and outputs the analog signal Sa1 as a spread spectrum signal to one end of the cable under test.

9. A cable detection device according to claim 8, characterized in that: When the cable under test is not disconnected from the external device: The signal analysis module also adjusts the test parameters according to the analysis results, and outputs the new test parameters to the signal generation module through feedback information, so that the signal generation module adjusts the test vector according to the new parameters and performs a new round of testing; The signal analysis module obtains a model curve of the final cable aging state according to the results of multiple rounds of testing and a comparison algorithm.

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