A method for detecting communication cables in intelligent engineering

Abstract

The application discloses a kind of detection methods of communication cable in intelligent engineering, it is related to communication cable detection technical field, comprising: according to common mode test voltage signal and near-end common mode current form common mode reflection coefficient spectrum, according to common mode test voltage signal and differential mode conversion voltage form longitudinal conversion transfer function spectrum;From each longitudinal conversion transfer function spectrum extraction group delay extreme value corresponding time delay, and the group delay extreme value corresponding time delay that appears repeatedly across physical layer idle window is determined as candidate longitudinal conversion time delay;According to the reflection phase in common mode reflection coefficient spectrum, determine terminal reflection time delay interval, and the candidate longitudinal conversion time delay earlier than the starting time of terminal reflection time delay interval is determined as cable side longitudinal conversion time delay;According to cable side longitudinal conversion time delay conversion longitudinal conversion abnormal position, and according to longitudinal conversion abnormal position and termination position generation detection result;The application is favorable to distinguish terminal influence and locate cable anomaly in on-line load detection.

Description

Technical Field

[0001] This invention relates to the field of communication cable testing technology, and more specifically to a testing method for communication cables in intelligent engineering. Background Technology

[0002] In intelligent building engineering, communication cables typically handle continuous communication between field terminals and back-end equipment. After project delivery, these cables remain under continuous service load, and their operational quality is affected not only by their installation condition but also by the termination contact status and changes in terminal load. As the integration level of building intelligent systems increases, the impact of communication link anomalies on field service continuity grows, leading to a growing need for online testing of communication cables during the maintenance phase.

[0003] Current communication cable testing is mostly based on offline testing, which typically requires disconnecting the existing link before connecting the testing equipment. This method can obtain relatively direct link parameters, but it is not suitable for operational scenarios with high service continuity requirements. If electrical responses are directly collected under load, response changes caused by the terminal's operating state can easily overlap with cable fixation anomalies, making it difficult to distinguish the source of the anomaly, thus affecting the reliability of fault location and the efficiency of on-site troubleshooting. Summary of the Invention

[0004] The purpose of this invention is to provide a method for detecting communication cables in intelligent engineering, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for detecting communication cables in intelligent engineering, comprising:

[0007] During the communication link service carrying period, the common-mode test voltage signal is coupled to the balanced line pair in the physical layer idle window to collect the near-end common-mode current and differential-mode conversion voltage.

[0008] A common-mode reflection coefficient spectrum is formed based on the common-mode test voltage signal and the near-end common-mode current, and a longitudinal transfer function spectrum is formed based on the common-mode test voltage signal and the differential-mode conversion voltage.

[0009] Extract the delay corresponding to the group delay extremum from the spectrum of each longitudinal transfer function, and determine the delay corresponding to the group delay extremum that recurs across the physical layer free window as candidate longitudinal transfer delays;

[0010] The terminal reflection delay interval is determined based on the reflection phase in the common-mode reflection coefficient spectrum, and the candidate longitudinal conversion delay earlier than the start time of the terminal reflection delay interval is determined as the cable-side longitudinal conversion delay;

[0011] The longitudinal conversion anomaly location is calculated based on the longitudinal conversion delay on the cable side, and the detection result is generated based on the longitudinal conversion anomaly location and the termination location.

[0012] The technical effects and advantages provided by the present invention in the above technical solution are as follows:

[0013] This invention utilizes the physical layer idle window to couple common-mode test signals during communication link service carrying, forming a common-mode reflection coefficient spectrum and a longitudinal conversion transfer function spectrum respectively. This establishes a correspondence between the cable's common-mode reflection response and longitudinal conversion response under the same test time scale. Furthermore, it uses the recurring group delay extrema across the physical layer idle window to determine candidate longitudinal conversion delays, and eliminates the influence of terminal load by using the terminal reflection delay interval. This allows longitudinal conversion anomalies on the cable side to be separated from the load-bearing response. Therefore, while reducing the risk of service interruption, it can locate and determine the termination position or cable segment, improving the reliability of communication cable testing results and the efficiency of fault diagnosis during the intelligent engineering operation and maintenance phase. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0015] Figure 1 This is a flowchart illustrating a method for detecting communication cables in intelligent engineering, as provided in an embodiment of the present invention. Detailed Implementation

[0016] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided to make the description of this application more complete and comprehensive, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The drawings are merely illustrative illustrations of this application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0017] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more exemplary embodiments. Numerous specific details are provided in the following description to give a full understanding of the exemplary embodiments disclosed in this application. However, those skilled in the art will recognize that the technical solutions disclosed in this application can be practiced with one or more specific details omitted, or other methods, components, steps, etc., can be employed. In other instances, well-known structures, methods, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of the disclosure of this application.

[0018] Example 1

[0019] like Figure 1 As shown, this embodiment discloses a method for detecting communication cables in intelligent engineering. The communication cable is a balanced pair connecting a near-end communication device and a remote terminal device. The near-end communication device is a switch, controller, or communication gateway with a communication port. The remote terminal device is a video surveillance terminal, access control terminal, wireless access terminal, or building control terminal. During the detection period, the communication link maintains a service-bearing state. Service-bearing state means that the communication link maintains the existing link connection and transmits service data according to the existing communication protocol. Multiple physical layer idle windows are selected within one detection cycle. Each physical layer idle window is used to carry the coupling timing of the common-mode test voltage signal and the response acquisition timing. The acquired data includes the common-mode test voltage signal, near-end common-mode current, and differential-mode conversion voltage. The method includes:

[0020] S101: During the communication link service carrying period, couple the common-mode test voltage signal to the balanced line pair in the physical layer idle window, and collect the near-end common-mode current and differential-mode conversion voltage;

[0021] S102: A common-mode reflection coefficient spectrum is formed based on the common-mode test voltage signal and the near-end common-mode current; a longitudinal transfer function spectrum is formed based on the common-mode test voltage signal and the differential-mode conversion voltage.

[0022] S103: Extract the delay corresponding to the group delay extremum from the spectrum of each longitudinal conversion transfer function, and determine the delay corresponding to the group delay extremum that recurs across the physical layer free window as candidate longitudinal conversion delays;

[0023] S104: Determine the terminal reflection delay interval based on the reflection phase in the common-mode reflection coefficient spectrum, and determine the candidate longitudinal conversion delay earlier than the start time of the terminal reflection delay interval as the cable-side longitudinal conversion delay;

[0024] S105: Calculate the longitudinal conversion anomaly location based on the longitudinal conversion delay on the cable side, and generate the detection result based on the longitudinal conversion anomaly location and the termination location.

[0025] Specifically, the physical layer idle window is determined based on the physical layer idle symbols in the communication link. A physical layer idle symbol is a physical layer symbol that maintains link synchronization but does not carry valid service data. The detection unit obtains the physical layer symbol status of the near-end communication device through a media-independent interface or by reading the physical layer configuration register of the near-end communication device, and determines the physical layer idle window based on the start and end timestamps of the physical layer idle symbols. Multiple physical layer idle windows are selected within one detection cycle. Each physical layer idle window covers the complete test cycle of the common-mode test voltage signal. Each physical layer idle window corresponds to a set of common-mode test voltage signal sampling sequences, near-end common-mode current sampling sequences, and differential-mode conversion voltage sampling sequences.

[0026] The common-mode test voltage signal is a test signal applied to the balanced conductor pair in a common-mode manner. Common-mode means that the two conductors of the balanced conductor pair have voltage changes in the same direction relative to the reference ground. The frequency band of the common-mode test voltage signal is isolated from the frequency band of the communication link service signal. This frequency band isolation means that the effective frequency range of the common-mode test voltage signal is distinct from the effective frequency range of the differential-mode service signal, or that filtering creates separable components in the frequency domain for the common-mode test voltage signal and the differential-mode service signal. The common-mode test voltage signal is not used as a modulation signal for the communication link service data, nor does it change the encoding method of the differential-mode service signal in the communication link.

[0027] Furthermore, the near-end common-mode current is the same-direction current component in the two conductors of the balanced line pair at the near-end test point. The near-end common-mode current characterizes the input response of the balanced line pair under common-mode excitation. The differential-mode conversion voltage is the inter-line voltage component generated by the balanced line pair in response to the common-mode test voltage signal. The differential-mode conversion voltage characterizes the response of the common-mode signal to be converted into a differential-mode signal in the balanced line pair. The acquisition timescale of the near-end common-mode current corresponds to the coupling timescale of the common-mode test voltage signal. The acquisition timescale of the differential-mode conversion voltage also corresponds to the coupling timescale of the common-mode test voltage signal. This timescale correspondence ensures that the common-mode test voltage signal, near-end common-mode current, and differential-mode conversion voltage within the same physical layer idle window share a common time reference.

[0028] In actual operation, the detection unit couples the common-mode test voltage signal to the balanced line pair at the near-end test point through a common-mode coupling circuit. The common-mode coupling circuit employs a common-mode injection transformer, a common-mode coupling network, or an isolation coupling network. The near-end common-mode current is obtained through a current sampling circuit. The differential-mode conversion voltage is obtained through a differential sampling circuit. The common-mode test voltage signal, near-end common-mode current, and differential-mode conversion voltage are acquired using the same sampling clock, or according to sampling clocks with a defined timescale correspondence. After acquisition, the detection unit records the window identifier of the physical layer idle window, the window start and end timestamps, the common-mode test voltage signal sampling sequence, the near-end common-mode current sampling sequence, and the differential-mode conversion voltage sampling sequence.

[0029] It should be noted that when the balanced wire pair is in a balanced state, the common-mode test voltage signal does not produce a stable differential-mode conversion response. When there are abnormalities in the termination contact, wire pair structure, local pressure condition, or bending condition of the balanced wire pair, the common-mode test voltage signal will generate a differential-mode conversion voltage at the corresponding location. The above acquisition method can obtain the common-mode input response and longitudinal conversion response while maintaining service carrying status in the communication link, providing basic data for subsequent differentiation between terminal reflection effects and longitudinal conversion anomalies on the cable side.

[0030] Specifically, this processing uses the common-mode test voltage signal, near-end common-mode current, and differential-mode conversion voltage obtained within the aforementioned physical layer idle window as data sources. Each physical layer idle window generates a corresponding common-mode reflection coefficient spectrum and longitudinal conversion transfer function spectrum. The common-mode reflection coefficient spectrum is used to characterize the reflection response of the balanced line pair under common-mode excitation. The longitudinal conversion transfer function spectrum is used to characterize the frequency domain response of the common-mode test voltage signal converted into the differential-mode conversion voltage. Since both types of spectral functions are formed by the common-mode test voltage signal within the same physical layer idle window, the two types of spectral functions have the same window time scale reference and frequency point reference.

[0031] Specifically, the step of forming a common-mode reflection coefficient spectrum based on the common-mode test voltage signal and the near-end common-mode current within the free window of each physical layer includes:

[0032] The common-mode test voltage signal and near-end common-mode current within the same physical layer free window are transformed in the frequency domain to obtain the frequency domain components of the common-mode voltage and the common-mode current.

[0033] To facilitate frequency domain analysis, the common-mode test voltage signal within the same physical layer free window is used as the common-mode voltage sampling sequence, and the near-end common-mode current within the same physical layer free window is used as the common-mode current sampling sequence. The detection unit performs frequency domain transformation on the common-mode voltage sampling sequence to obtain the common-mode voltage frequency component. The detection unit also performs frequency domain transformation on the common-mode current sampling sequence to obtain the common-mode current frequency component. The frequency domain transformation uses the same frequency point index. The common-mode voltage frequency domain component is denoted as The common-mode current frequency domain component is denoted as Same frequency corresponding and They originate from the same physical layer free window and have the same frequency index.

[0034] As a feasible processing method, frequency domain transformation employs discrete Fourier transform. Let the common-mode voltage sampling sequence within the same physical layer free window be... The near-end common-mode current sampling sequence is The number of sampling points is , No. The discrete frequency points are Then the common-mode voltage frequency domain components and the common-mode current frequency domain components are respectively:

[0035] ;

[0036] ;

[0037] in, The sampling point number, For discrete frequency points, The unit is the imaginary unit. The above frequency domain transformation enables the common-mode test voltage signal and the near-end common-mode current to form corresponding frequency domain components at the same frequency point, avoiding the lack of a corresponding frequency point basis for subsequent common-mode input impedance calculation.

[0038] Calculate the common-mode input impedance spectrum and the common-mode reflection coefficient spectrum using the formula.

[0039] ;

[0040] ;

[0041] in, For frequency point The corresponding common-mode input impedance, For frequency point The corresponding common-mode voltage frequency domain component, For frequency point The corresponding common-mode current frequency domain component, For frequency point The corresponding common-mode reflection coefficient, This is the common-mode characteristic impedance for the balancing line pair.

[0042] Furthermore, the common-mode input impedance spectrum is composed of the common-mode input impedance at each frequency point. Composition. The common-mode input impedance spectrum reflects the common-mode input characteristics of the balanced line pair observed at the near-end test point. The common-mode characteristic impedance can be determined based on the communication cable type, cable structural parameters, nominal test data, or calibration test data. The common-mode reflection coefficient spectrum consists of the common-mode reflection coefficients corresponding to each frequency point. Composition. The common-mode reflection coefficient spectrum is used to characterize the reflection characteristics formed when the common-mode test voltage signal propagates along the balance line pair, and provides a data basis for subsequently determining the terminal reflection delay interval based on the reflection phase.

[0043] It should be noted that this process does not directly use the phase of the common-mode input impedance spectrum as the reflection phase. Instead, it first calculates the common-mode reflection coefficient spectrum from the common-mode input impedance spectrum. Therefore, the reflection phase in the common-mode reflection coefficient spectrum has a clear physical meaning and can be directly applied to the subsequent calculation of the common-mode reflection group delay. This process avoids the misuse of the input impedance phase and the reflection coefficient phase and improves the physical consistency of the process for determining the terminal reflection delay interval.

[0044] The common-mode test voltage signal forms a separable component with the differential-mode service signal of the communication link in the frequency domain. This allows the frequency domain transformation to extract the frequency domain component corresponding to the common-mode test voltage signal, reducing the impact of the service signal on the common-mode reflection coefficient spectrum. The acquisition timescale of the differential-mode conversion voltage corresponds to the coupling timescale of the common-mode test voltage signal, ensuring that the input excitation and longitudinal conversion response within the same physical layer idle window have the same time base, providing a data foundation for calculating the longitudinal conversion transfer function spectrum.

[0045] Specifically, the step of forming a longitudinal transfer function spectrum based on the common-mode test voltage signal and differential-mode conversion voltage within the free window of each physical layer includes:

[0046] The common-mode test voltage signal and the differential-mode conversion voltage within the same physical layer free window are transformed in the frequency domain to obtain the frequency domain components of the common-mode voltage and the differential-mode voltage.

[0047] Specifically, the common-mode test voltage signal within the same physical layer's free window serves as the input signal for the longitudinal transfer function spectrum. The differential-mode conversion voltage within the same physical layer's free window serves as the output signal for the longitudinal transfer function spectrum. The detection unit performs a frequency domain transformation on the common-mode test voltage signal to obtain the common-mode voltage frequency domain component. The detection unit also performs a frequency domain transformation on the differential-mode conversion voltage to obtain the differential-mode voltage frequency domain component. The common-mode voltage frequency domain component maintains the same time-frequency reference as the aforementioned common-mode voltage frequency domain component used to calculate the common-mode input impedance spectrum, thereby ensuring a unified frequency point mapping relationship between the longitudinal transfer function spectrum and the common-mode reflection coefficient spectrum across the entire frequency band. For frequency points... The differential-mode voltage frequency domain component is denoted as Same frequency corresponding and They originate from the same physical layer free window and use the same frequency index.

[0048] As a feasible processing method, let the differential-mode conversion voltage sampling sequence be... The number of sampling points is , No. The discrete frequency points are Then the frequency domain component of the differential mode voltage is:

[0049] ;

[0050] in, For the first The differential-mode conversion voltage corresponds to each sampling point. Through this frequency domain transformation, the differential-mode conversion voltage can be converted into a frequency domain component corresponding to the common-mode test voltage signal, so that the longitudinal conversion relationship can be calculated in the frequency domain.

[0051] Calculate the longitudinal transfer function spectrum using the formula: ;in, For frequency point The corresponding vertical transfer function, For frequency point The corresponding differential-mode voltage frequency domain component, For frequency point The corresponding common-mode voltage frequency domain component.

[0052] Furthermore, the longitudinal transfer function spectrum is composed of the longitudinal transfer function corresponding to each frequency point. Composition. The longitudinal transfer function (LTF) represents the frequency domain proportionality of the conversion of the common-mode test voltage signal to the differential-mode converted voltage. This LTF contains amplitude and phase information. The amplitude information reflects the degree of conversion from common-mode to differential-mode. The phase information reflects the propagation delay characteristics of the longitudinal conversion response as a function of frequency. The phase information of the LTF spectrum is used to subsequently calculate the longitudinal conversion group delay curve and extract the delay corresponding to the group delay extrema.

[0053] After completing the above processing, the detection unit obtains the common-mode reflection coefficient spectrum and longitudinal transfer function spectrum corresponding to each physical layer free window. The common-mode reflection coefficient spectrum is used to subsequently determine the terminal reflection delay interval. The longitudinal transfer function spectrum is used to subsequently determine the candidate longitudinal transfer delay. The two types of spectral functions originate from the same common-mode test voltage signal, but correspond to the common-mode reflection response and the longitudinal transfer response, respectively. This dual-spectrum formation method can limit the terminal load influence range through the common-mode reflection response and locate the longitudinal transfer anomaly position of the balanced line pair through the longitudinal transfer response in subsequent processing.

[0054] Specifically, the longitudinal transfer function spectrum contains the longitudinal transfer function corresponding to each frequency point. The longitudinal transfer function has amplitude and phase information. The rate of change of the phase information with frequency is used to characterize the propagation delay corresponding to the longitudinal transfer response. The detection unit processes the longitudinal transfer function spectrum corresponding to each physical layer idle window and extracts the delay corresponding to the group delay extremum from each longitudinal transfer function spectrum.

[0055] Candidate longitudinal conversion delays are not based on a single extreme group delay value within a physical layer free window. The detection unit repeatedly judges the delays corresponding to extreme group delay values ​​across multiple physical layer free windows. If the delay corresponding to the extreme group delay value appears repeatedly within multiple physical layer free windows, the longitudinal conversion response corresponding to that delay exhibits delay stability. This delay stability corresponds to the cable termination contact state, the wire pair structure state, or local structural changes in the cable path. Therefore, candidate longitudinal conversion delays can reduce the impact of single-shot acquisition noise and transient service disturbances on the positioning results, providing a candidate delay basis for subsequent determination of the cable-side longitudinal conversion delay.

[0056] Specifically, determining the delay corresponding to the recurring extreme value of group delay across physical layer free windows as the candidate longitudinal transition delay includes:

[0057] The longitudinal transfer function spectrum is used to calculate the longitudinal transfer group delay curve based on the rate of change of phase with respect to frequency.

[0058] The detection unit reads the longitudinal transfer function spectrum corresponding to each physical layer free window. For frequency points... The vertical transfer function is denoted as The phase of the longitudinal transfer function is denoted as... Before calculating the longitudinal conversion group delay curve, the detection unit... Phase expansion is performed to make the phase change continuously with frequency. The longitudinally converted phase after phase expansion is used to calculate the longitudinally converted group delay curve.

[0059] The longitudinal conversion group delay curve is calculated using the following formula:

[0060] ;

[0061] in, For frequency point The corresponding vertical conversion group delay, For the longitudinal transfer function spectrum at frequency points The expanded phase. For discrete frequency points, the frequency change rate is calculated using the difference between adjacent frequency points. Let the adjacent frequency points be... and The corresponding longitudinal conversion group delay is expressed as:

[0062] ;

[0063] Through the above calculations, a longitudinal conversion group delay curve is obtained for each physical layer idle window. The input data for the longitudinal conversion group delay curve is the phase of the longitudinal conversion transfer function spectrum, and the output data is the longitudinal conversion group delay corresponding to each frequency point. This processing converts the phase changes in the longitudinal conversion transfer function spectrum into delay characteristics, enabling comparison of the longitudinal conversion response in the delay domain.

[0064] Extract the delay corresponding to the extreme value of group delay from the longitudinal transformation group delay curve;

[0065] Specifically, the detection unit extracts the extreme values ​​of group delay from the longitudinal conversion group delay curve. The extreme values ​​of group delay are the delay points in the longitudinal conversion group delay curve that exhibit local peaks or valleys relative to adjacent frequency points. The detection unit determines the extreme values ​​of group delay based on the change in the sign of the difference in group delay values ​​at adjacent frequency points. If the sign of the group delay difference changes from positive to negative before and after a certain frequency point, that frequency point corresponds to a local peak; if the sign of the group delay difference changes from negative to positive before and after a certain frequency point, that frequency point corresponds to a local valley. The detection unit determines the group delay corresponding to the local peak or local valley as the delay corresponding to the extreme value of group delay.

[0066] It should be noted that the group delay extremum corresponds to the delay used to characterize the concentrated location of the longitudinal conversion response in the propagation delay. Abnormal cable termination, decreased wire pair balance, or local structural disturbances can cause the common-mode signal to convert to a differential-mode signal. This conversion response manifests as a phase change with a concentrated propagation delay in the frequency domain. Therefore, extracting the group delay extremum corresponding to the delay from the longitudinal conversion group delay curve can convert the frequency domain phase characteristics in the longitudinal conversion transfer function spectrum into delay characteristics for positioning. This process reduces the dependence on amplitude fluctuations when relying solely on the amplitude of the longitudinal conversion transfer function spectrum, allowing the subsequent positioning process to be based on these delay characteristics.

[0067] The delay corresponding to the extreme value of group delay that occurs in the same delay resolution unit and across the physical layer free window is determined as the candidate longitudinal conversion delay.

[0068] Specifically, the detection unit compares the group delay extreme values ​​corresponding to the delays obtained from different physical layer free windows. During the comparison, the delay resolution unit is used as the judgment unit. If the group delay extreme values ​​corresponding to the delays in multiple physical layer free windows are located in the same delay resolution unit, then these group delay extreme values ​​are considered to have appeared repeatedly in the delay domain. The detection unit determines the group delay extreme values ​​corresponding to the delays that are located in the same delay resolution unit and appear across physical layer free windows as candidate vertical conversion delays.

[0069] The time delay resolution unit is determined by the time resolution corresponding to the bandwidth of the common-mode test voltage signal, and the physical layer idle window covers the complete test cycle of the common-mode test voltage signal.

[0070] The delay resolution unit is used to determine whether the group delay extrema in different physical layer idle windows belong to the same delay position. The bandwidth of the common-mode test voltage signal is denoted as... The corresponding time resolution is expressed as: ;

[0071] In the formula, For time resolution, This refers to the bandwidth of the common-mode test voltage signal. The detection unit is configured according to... Delay resolution units are defined. The delays corresponding to the group delay extrema within the same delay resolution unit are considered to correspond to the same longitudinal conversion delay position. The physical layer idle window covers the complete test cycle of the common-mode test voltage signal, which can ensure that the common-mode test voltage signal, near-end common-mode current, and differential-mode conversion voltage have complete cycle data during frequency domain transformation, reducing the impact of window truncation on group delay calculation.

[0072] Candidate longitudinal transition delays are derived from the longitudinal transition transfer function spectrum and are repeatedly verified through cross-physical layer idle windows. This process improves the stability of longitudinal transition anomaly delay extraction and provides input data for subsequent elimination of terminal load influence by combining terminal reflection delay intervals.

[0073] Specifically, the reflection phase in the common-mode reflection coefficient spectrum reflects the phase change of the common-mode test voltage signal after propagation along the balanced line pair. At the link termination point, there are terminal equipment input impedances, port loads, and termination structures, which typically create a reflection phase change in the common-mode reflection coefficient spectrum corresponding to the two-way propagation delay of the link termination. The detection unit first determines the terminal reflection delay interval based on the reflection phase in the common-mode reflection coefficient spectrum, and then uses this terminal reflection delay interval to constrain candidate longitudinal transition delays, thereby reducing the possibility of mistaking the longitudinal transition response caused by the terminal load as a longitudinal transition anomaly on the cable side.

[0074] The input data for this process includes the common-mode reflection coefficient spectrum and candidate longitudinal conversion delays. The output data includes the terminal reflection delay interval and the cable-side longitudinal conversion delay. The terminal reflection delay interval represents the delay range within which the link terminal reflection effect occurs. The cable-side longitudinal conversion delay is a candidate longitudinal conversion delay earlier than the start time of the terminal reflection delay interval, used for subsequent calculation of longitudinal conversion anomaly locations.

[0075] Specifically, determining the terminal reflection delay interval based on the reflection phase in the common-mode reflection coefficient spectrum includes:

[0076] Phase expansion is performed on the reflection phase in the common-mode reflection coefficient spectrum to obtain the common-mode reflection phase curve;

[0077] The detection unit reads the common-mode reflection coefficient spectrum corresponding to the free window of each physical layer. For frequency points... The common-mode reflection coefficient is denoted as The reflection phase in the common-mode reflection coefficient spectrum is... The phase, denoted as Since frequency domain phase is usually represented by a principal value range, phase jumps may occur between adjacent frequency points. The detection unit... Phase expansion is performed to obtain a continuously varying common-mode reflection phase curve.

[0078] Phase unrolling eliminates non-physical jumps caused by the principal phase range, ensuring a continuous relationship between the common-mode reflection phase and frequency. After phase unrolling, the common-mode reflection phase curve is used to calculate the common-mode reflection group delay. This process ensures that subsequent frequency slope calculations are based on the continuous phase curve, avoiding anomalies in common-mode reflection group delay calculations caused by phase jumps.

[0079] The common-mode reflection group delay is calculated based on the frequency slope of the common-mode reflection phase curve, and the range of common-mode reflection group delay that matches the two-way propagation delay of the link terminal is determined as the terminal reflection delay interval.

[0080] The detection unit calculates the common-mode reflection group delay based on the frequency slope of the common-mode reflection phase curve. Let the common-mode reflection phase curve be... The common-mode reflection group delay is expressed as: ;

[0081] in, For frequency point The corresponding common-mode reflection group delay, The common-mode reflection coefficient spectrum at frequency point The expanded phase. For discrete frequency points, the common-mode reflection group delay is calculated using the difference between adjacent frequency points.

[0082] The two-way propagation delay at the link termination is determined based on the link length and the nominal propagation speed of the communication cable. The link length is read from the as-built wiring record or determined by the measurement of the communication cable length. Let the link length be... The nominal propagation speed of the communication cable is The two-way propagation delay at the link terminal is expressed as: ;

[0083] in, This is the two-way propagation delay at the link termination. The detection unit searches for the common-mode reflection group delay. A matching group delay range is determined, and this group delay range is defined as the terminal reflection delay interval. The matching indicates that the common-mode reflection group delay is within the allowable delay range jointly determined by the link length measurement error, the nominal propagation speed error, and the delay resolution unit. This allowable delay range is determined by the delay resolution of the detection system and the nominal propagation speed of the communication cable.

[0084] Through the above processing, the terminal reflection delay interval has a clear data source and physical meaning. This interval corresponds to the delay range where the link terminal reflection effect occurs. If the candidate longitudinal conversion delay is within this interval, it may be affected by the input impedance of the terminal device, port load, or terminal connection status. If the candidate longitudinal conversion delay is earlier than the start time of this interval, the corresponding position is located in the cable path or termination position before the link terminal, which can be used as a basis for locating longitudinal conversion anomalies on the cable side.

[0085] The detection unit compares the candidate longitudinal transition delay with the start time of the terminal reflection delay interval. Candidate longitudinal transition delays earlier than the start time of the terminal reflection delay interval are identified as cable-side longitudinal transition delays. This process utilizes common-mode reflection response to limit the impact range of terminal load and filters out the delay of the corresponding cable-side path from the longitudinal transition delays, reducing the interference of terminal load state changes on the location of longitudinal transition anomalies.

[0086] Specifically, the input data for this process includes the longitudinal transition delay on the cable side, the nominal propagation speed of the communication cable, and the termination location. The longitudinal transition delay on the cable side is determined by the above processing. The nominal propagation speed of the communication cable is determined by the type of communication cable, its nominal parameters, or the results of on-site calibration. The termination location is read from the as-built wiring record. The output of this process is the detection result, which includes at least the location of the longitudinal transition anomaly and its correspondence with the termination location.

[0087] Specifically, the step of generating detection results based on the longitudinal transformation anomaly location and termination location includes:

[0088] The longitudinal conversion delay on the cable side is converted into the longitudinal conversion anomaly location according to the formula. ;in, This refers to the cable distance from the longitudinally converted abnormal location to the near-end test point. The nominal propagation speed of the communication cable. For the longitudinal conversion delay on the cable side;

[0089] The detection unit calculates the location of the longitudinal transition anomaly based on the longitudinal transition delay on the cable side. The longitudinal transition delay on the cable side corresponds to the total propagation time of the common-mode test voltage signal from the near-end test point to the longitudinal transition anomaly location, and the differential-mode transition response from the longitudinal transition anomaly location back to the near-end test point. For ease of engineering conversion, the common-mode propagation speed and differential-mode propagation speed of communication cables use the same nominal propagation speed. This indicates that when it is necessary to improve the accuracy of distance conversion, the nominal propagation speed... Obtained through on-site calibration. The longitudinal conversion delay on the cable side is converted into the cable distance from the longitudinal conversion anomaly location to the near-end test point. The division in the formula... Used to convert two-way transmission distance into one-way cable distance.

[0090] The abnormal vertical conversion location is matched with the termination location in the as-built wiring record to generate the detection result.

[0091] The as-built wiring record includes the near-end test points of the communication cables, the patch panel termination locations, the information module termination locations, the far-end terminal termination locations, and the corresponding cable distances for each termination location. The detection unit reads the termination locations from the as-built wiring record and matches the cable distances corresponding to the longitudinal conversion anomaly locations with the cable distances corresponding to the termination locations. If the cable distance corresponding to the longitudinal conversion anomaly location falls within the distance range corresponding to the termination location, the detection result records that a longitudinal conversion anomaly exists at that termination location. If the longitudinal conversion anomaly location is located between adjacent termination locations, the detection result records that a longitudinal conversion anomaly exists in the corresponding cable segment.

[0092] The test results include the communication link identifier, the cable distance from the longitudinal conversion anomaly location to the near-end test point, the matching termination location or cable segment, and the test time. Based on the test results, maintenance personnel can conduct on-site verification of the termination location or cable segment. This process allows the test results to be further located from the communication link anomaly to the termination location or cable segment, narrowing the scope of troubleshooting during online operation and maintenance.

[0093] During communication link service carrying, a common-mode test voltage signal is coupled using a physical layer idle window, generating a common-mode reflection coefficient spectrum and a longitudinal conversion transfer function spectrum. The longitudinal conversion transfer function spectrum is used to extract candidate longitudinal conversion delays that recur across the physical layer idle window. The common-mode reflection coefficient spectrum is used to determine the terminal reflection delay interval. By filtering candidate longitudinal conversion delays through the terminal reflection delay interval, the cable-side longitudinal conversion delay can be determined, and the location of longitudinal conversion anomalies can be calculated accordingly. This process separates the impact of terminal load reflection from cable-side longitudinal conversion anomalies in the delay domain, enabling communication cable detection while maintaining communication link service carrying capacity.

[0094] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for detecting communication cables in intelligent engineering, characterized in that, include: During the communication link service carrying period, the common-mode test voltage signal is coupled to the balanced line pair in the physical layer idle window to collect the near-end common-mode current and differential-mode conversion voltage. A common-mode reflection coefficient spectrum is formed based on the common-mode test voltage signal and the near-end common-mode current, and a longitudinal transfer function spectrum is formed based on the common-mode test voltage signal and the differential-mode conversion voltage. Extract the delay corresponding to the group delay extremum from the spectrum of each longitudinal transfer function, and determine the delay corresponding to the group delay extremum that recurs across the physical layer free window as candidate longitudinal transfer delays; The terminal reflection delay interval is determined based on the reflection phase in the common-mode reflection coefficient spectrum, and the candidate longitudinal conversion delay earlier than the start time of the terminal reflection delay interval is determined as the cable-side longitudinal conversion delay; The longitudinal conversion anomaly location is calculated based on the longitudinal conversion delay on the cable side, and the detection result is generated based on the longitudinal conversion anomaly location and the termination location.

2. The method according to claim 1, characterized in that, The process of forming a common-mode reflection coefficient spectrum based on the common-mode test voltage signal and the near-end common-mode current within the free window of each physical layer includes: The common-mode test voltage signal and near-end common-mode current within the same physical layer free window are transformed in the frequency domain to obtain the frequency domain components of the common-mode voltage and the common-mode current. Calculate the common-mode input impedance spectrum and the common-mode reflection coefficient spectrum using the formula. ； ； in, For frequency point The corresponding common-mode input impedance, For frequency point The corresponding common-mode voltage frequency domain component, For frequency point The corresponding common-mode current frequency domain component, For frequency point The corresponding common-mode reflection coefficient, This is the common-mode characteristic impedance for the balancing line pair.

3. The method according to claim 1, characterized in that, Before coupling the common-mode test voltage signal to the balanced line pair within the physical layer free window, the process further includes: The detection unit obtains the physical layer symbol status of the near-end communication device through a media-independent interface or by reading the physical layer configuration register of the near-end communication device. The physical layer free window is determined based on the start and end timestamps of the physical layer free symbol.

4. The method according to claim 1, characterized in that, The differential-mode conversion voltage is the inter-line voltage component generated by the balanced line pair in response to the common-mode test voltage signal, and the acquisition timescale of the differential-mode conversion voltage corresponds to the coupling timescale of the common-mode test voltage signal.

5. The method according to claim 1, characterized in that, The process of forming a longitudinal transfer function spectrum based on the common-mode test voltage signal and differential-mode conversion voltage within the free window of each physical layer includes: The common-mode test voltage signal and the differential-mode conversion voltage within the same physical layer free window are transformed in the frequency domain to obtain the frequency domain components of the common-mode voltage and the differential-mode voltage. Calculate the longitudinal transfer function spectrum using the formula: ;in, For frequency point The corresponding vertical transfer function, For frequency point The corresponding differential-mode voltage frequency domain component, For frequency point The corresponding common-mode voltage frequency domain component.

6. The method according to claim 1, characterized in that, The step of determining the delay corresponding to the extreme value of the group delay that recurs across the physical layer free window as the candidate longitudinal transition delay includes: The longitudinal transfer function spectrum is used to calculate the longitudinal transfer group delay curve based on the rate of change of phase with respect to frequency. Extract the delay corresponding to the extreme value of group delay from the longitudinal transformation group delay curve; The delay corresponding to the extreme value of group delay that occurs in the same delay resolution unit and across the physical layer free window is determined as the candidate longitudinal conversion delay.

7. The method according to claim 6, characterized in that, The time delay resolution unit is determined by the time resolution corresponding to the bandwidth of the common-mode test voltage signal, and the physical layer idle window covers the complete test cycle of the common-mode test voltage signal.

8. The method according to claim 1, characterized in that, Determining the terminal reflection delay interval based on the reflection phase in the common-mode reflection coefficient spectrum includes: Phase expansion is performed on the reflection phase in the common-mode reflection coefficient spectrum to obtain the common-mode reflection phase curve; The common-mode reflection group delay is calculated based on the frequency slope of the common-mode reflection phase curve, and the range of common-mode reflection group delay that matches the two-way propagation delay of the link terminal is determined as the terminal reflection delay interval.

9. The method according to claim 1, characterized in that, The generation of detection results based on the longitudinal transformation anomaly location and termination location includes: The longitudinal conversion delay on the cable side is converted into the longitudinal conversion anomaly location according to the formula. ;in, This refers to the cable distance from the longitudinally converted abnormal location to the near-end test point. The nominal propagation speed of the communication cable. For the longitudinal conversion delay on the cable side; The abnormal vertical conversion location is matched with the termination location in the as-built wiring record to generate the detection result.

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