Determination device and determination method

Abstract

This determination device comprises: a signal output unit that outputs a measurement signal having a frequency component to a transmission line; a signal reception unit that receives, from the transmission line, a response signal including a signal resulting from reflection of the measurement signal; an acquisition unit that acquires a plurality of evaluation values based on at least one of the amplitude and the phase of the response signal received by the signal reception unit; and a determination unit that determines abnormality of the transmission line on the basis of the distribution of the evaluation values acquired by the acquisition unit.

Description

Determination device and determination method

[0001] This application claims priority to Japanese Patent Application No. 2023-025672 filed on February 22, 2023, and incorporates by reference all of the contents of said Japanese application.

[0002] Conventionally, techniques for predicting disconnections in transmission lines have been proposed. For example, Patent Document 1 (JP 2007-305478 A) discloses the following device for determining disconnection of an electric cable. That is, the device for determining disconnection of an electric cable includes an electric cable including a plurality of electric wires, an electric shield layer covering the plurality of electric wires, and a sheath covering the electric shield layer, a disconnection determination line provided in the electric shield layer and including a conductor wire and an insulating layer surrounding the conductor wire, a voltage source electrically connected to the conductor wires, a first detector electrically connected to the conductor wires, and a second detector electrically connected to the electric shield layer.

[0003] Japanese Patent Application Laid-Open No. 2007-305478

[0004] The determination device disclosed herein includes a signal output unit that outputs a measurement signal having a frequency component to a transmission line, a signal receiving unit that receives a response signal from the transmission line that includes a signal that is a reflection of the measurement signal, an acquisition unit that acquires multiple evaluation values ​​based on at least one of the amplitude and phase of the response signal received by the signal receiving unit, and a determination unit that determines an abnormality in the transmission line based on the distribution of the evaluation values ​​acquired by the acquisition unit.

[0005] One aspect of the present disclosure can be realized not only as a determination device including such a characteristic processing unit, but also as a program for causing a computer to execute steps of such characteristic processing, as a semiconductor integrated circuit that realizes part or all of the determination device, or as a system including the determination device.

[0006] FIG. 1 is a diagram illustrating a configuration of a communication system according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating a configuration of a relay device according to an embodiment of the present disclosure. FIG. 3 is a diagram illustrating an example of a time-dependent change in a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 4 is a diagram illustrating another example of a time-dependent change in a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 5 is a diagram illustrating a correspondence relationship between phase differences θop, θsh and distances Lop, Lsh calculated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 6 is a diagram illustrating a correspondence relationship between phase differences θop, θsh and distances Lop, Lsh calculated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 7 is a diagram illustrating another example of a time-dependent change in a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 8 is a diagram illustrating an example of a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 9 is a diagram illustrating another example of a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 10 is a diagram illustrating another example of a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 11 is a diagram illustrating an example of a change over time in a frequency distribution F2 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 12 is a diagram illustrating another example of a change over time in a frequency distribution F2 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 13 is a diagram illustrating another example of a change over time in a frequency distribution F2 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 14 is a diagram illustrating an example of a frequency distribution F2 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 15 is a diagram illustrating another example of a frequency distribution F2 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 16 is a diagram illustrating another example of a frequency distribution F2 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 17 is a diagram illustrating another example of a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure. FIG. 18 is a flowchart defining an example of an operational procedure when a relay device according to an embodiment of the present disclosure performs a determination process.19 and 20 are flowcharts illustrating an example of an operation procedure when a relay device according to an embodiment of the present disclosure performs a determination process.

[0007] [Problem to be Solved by the Present Disclosure] There is a need for a technology that goes beyond the technology described in Patent Document 1 and that is capable of more accurately determining abnormalities in a transmission line.

[0008] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a determination device and a determination method that can more accurately determine an abnormality in a transmission line.

[0009] [Effects of the Present Disclosure] According to the present disclosure, an abnormality in a transmission line can be determined more accurately.

[0010] First, the contents of the embodiments of the present disclosure will be listed and described.

[0011] (1) A determination device according to an embodiment of the present disclosure includes a signal output unit that outputs a measurement signal having frequency components to a transmission line; a signal receiving unit that receives a response signal from the transmission line, the response signal including a signal that is a reflection of the measurement signal; an acquisition unit that acquires multiple evaluation values ​​based on at least one of the amplitude and phase of the response signal received by the signal receiving unit; and a determination unit that determines an abnormality in the transmission line based on the distribution of the evaluation values ​​acquired by the acquisition unit.

[0012] In this way, a measurement signal having a frequency component is output to a transmission line, an evaluation value is obtained based on a response signal received from the transmission line, and an abnormality in the transmission line is determined based on the distribution of the obtained evaluation values. This configuration allows abnormality determination to be performed based on statistics of evaluation values ​​obtained multiple times, thereby improving the reliability of abnormality determination and enabling more accurate abnormality determination in the transmission line.

[0013] (2) In the above (1), the determining unit may determine whether or not there is an abnormality in the transmission line based on a change over time in a statistical quantity indicated by the distribution.

[0014] With this configuration, for example, it is possible to more accurately determine the occurrence and progression of an abnormality based on a change in a statistical quantity relative to a statistical quantity in a state where no abnormality has occurred in the transmission line.

[0015] (3) In the above (1) or (2), the determining unit may determine an abnormality in the transmission line based on a correlation between the distribution and a predetermined distribution.

[0016] With this configuration, for example, it is possible to more accurately determine the occurrence and progression of an abnormality based on a correlation with the distribution when no abnormality has occurred in the transmission line.

[0017] (3) In any one of (1) to (3) above, the determining unit may further determine a type of abnormality that has occurred in the transmission line based on the distribution.

[0018] With this configuration, maintenance plans such as replacement of transmission lines can be efficiently made depending on the type of abnormality that has been determined.

[0019] (5) In the above (4), the determination unit may determine that the type of abnormality occurring in the transmission line is at least one of a break in the transmission line, a short circuit in the transmission line, and deterioration of the transmission line.

[0020] With this configuration, it is possible to more accurately determine whether or not the transmission line needs to be replaced depending on the type of abnormality that is determined.

[0021] (6) In any of (1) to (5) above, the acquisition unit may acquire a first evaluation value that is the evaluation value based on the amplitude and a second evaluation value that is the evaluation value based on the phase, and the determination unit may determine an abnormality in the transmission line based on a distribution of the first evaluation value and a distribution of the second evaluation value.

[0022] With this configuration, it is possible to more accurately determine whether a transmission line has an abnormality. For example, it is possible to determine whether a transmission line has a short circuit or has deteriorated, and whether a transmission line has an open circuit or has deteriorated.

[0023] (7) In the above (6), the determination unit may determine, based on the distribution of the first evaluation value and the distribution of the second evaluation value, that the type of abnormality that has occurred in the transmission line is a break in the transmission line, a short circuit in the transmission line, or deterioration of the transmission line.

[0024] With this configuration, it is possible to accurately determine whether a transmission line is broken, short-circuited, or deteriorated by using the distribution of the first evaluation value and the distribution of the second evaluation value.

[0025] (8) In the above (6) or (7), the determining unit may determine a position of an abnormality that has occurred in the transmission line based on a distribution of the second evaluation values.

[0026] With this configuration, the distribution of the second evaluation values ​​can be used to accurately determine the location of an abnormality in the transmission line.

[0027] (9) A determination method according to an embodiment of the present disclosure includes the steps of outputting a measurement signal having frequency components to a transmission line, receiving a response signal from the transmission line including a signal resulting from reflection of the measurement signal, acquiring an evaluation value based on at least one of the amplitude and phase of the received response signal, and determining an abnormality in the transmission line based on the distribution of the acquired evaluation values.

[0028] In this way, by using a method in which a measurement signal having a frequency component is output to a transmission line, an evaluation value is obtained based on a response signal received from the transmission line, and an abnormality in the transmission line is determined based on the distribution of the obtained evaluation values, the abnormality determination can be performed based on statistics of evaluation values ​​obtained multiple times, thereby improving the reliability of the abnormality determination and enabling more accurate abnormality determination in the transmission line.

[0029] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, identical or corresponding parts are designated by the same reference numerals, and their description will not be repeated. Furthermore, at least some of the embodiments described below may be combined in any manner.

[0030] 1 is a diagram showing a configuration of a communication system according to an embodiment of the present disclosure. Referring to FIG. 1, a communication system 301 includes a relay device 101 and a plurality of communication devices 111.

[0031] The relay device 101 is connected to each communication device 111 in a one-to-one relationship via a communication transmission line 51. More specifically, the transmission line 51 includes a cable portion and connector portions provided at a first end and a second end of the cable portion. The connector portion provided at the first end of the cable portion is connected to the relay device 101. The connector portion provided at the second end of the cable portion is connected to the communication device 111. The transmission line 51 may be a single wire or a pair of wires. The transmission line 51 is, for example, an Ethernet (registered trademark) cable.

[0032] The communication system 301 is mounted on a vehicle, for example. In this case, the communication device 111 is, for example, an on-board ECU (Electronic Control Unit). The communication system 301 may also be used in a home network or factory automation, for example.

[0033] The relay device 101 is capable of communicating with the communication device 111. The relay device 101 performs a relay process of, for example, relaying information exchanged between a plurality of communication devices 111 connected to different transmission lines 51. The relay device 101 also functions as a determination device, and performs a determination process of, for example, periodically determining an abnormality in the transmission line 51. More specifically, the transmission line 51 may be broken due to deterioration or may be short-circuited to another electric line or ground. The relay device 101 determines a break, short circuit, or the like in the transmission line 51 as an abnormality in the transmission line 51.

[0034] [Relay Device] FIG. 2 is a diagram illustrating the configuration of a relay device according to an embodiment of the present disclosure. Referring to FIG. 2, the relay device 101 includes a relay unit 10, multiple determination processing units 20, and multiple communication ports 30. The determination processing unit 20 includes a signal output unit 21, a signal receiving unit 22, a processing unit 23, and a storage unit 24. The processing unit 23 is an example of an acquisition unit and an example of a determination unit. Some or all of the relay unit 10, the signal output unit 21, the signal receiving unit 22, and the processing unit 23 are implemented, for example, by a processing circuit including one or more processors. The storage unit 24 is, for example, a non-volatile memory included in the processing circuit. The communication ports 30 are, for example, connectors or terminals. A connector portion of a transmission line 51 is connected to each communication port 30.

[0035] For example, the end of the transmission line 51 on the communication device 111 side is impedance-matched. However, this end of the transmission line 51 does not need to be impedance-matched accurately.

[0036] The repeater 101 outputs a measurement signal having a frequency component to the transmission line 51 and receives a response signal including a signal resulting from reflection of the measurement signal from the transmission line 51. The repeater 101 acquires a plurality of evaluation values ​​EV based on the amplitude and phase of the received response signal. The repeater 101 then determines an abnormality in the transmission line 51 based on the distribution of the acquired evaluation values ​​EV. Details of the processing in the repeater 101 will be described later.

[0037] <Relay Unit> The relay unit 10 performs relay processing to relay frames between communication devices 111. More specifically, the relay unit 10 receives a frame from a certain communication device 111 via a corresponding transmission line 51 and a corresponding communication port 30, and transmits the frame to another communication device 111 via the corresponding communication port 30 and the corresponding transmission line 51 in accordance with destination information such as the destination IP address, MAC address, and message ID of the frame. In other words, the relay unit 10 transmits and receives communication signals including frames to and from the communication device 111 via the communication port 30 and the transmission line 51.

[0038] <Determination Processing Unit> For example, the relay device 101 includes the same number of determination processing units 20 as the number of communication ports 30. More specifically, the determination processing units 20 are provided corresponding to the communication ports 30, and perform determination processing to determine whether there is an abnormality in the transmission line 51 connected to the corresponding communication port 30. Below, a description will be given of the determination processing performed by one determination processing unit 20 in the relay device 101 as a representative example.

[0039] (Signal Output Unit) The signal output unit 21 outputs a measurement signal having a frequency component to the transmission line 51. More specifically, the signal output unit 21 outputs an AC signal, a pulse signal, or a frequency sweep signal to the transmission line 51 as the measurement signal.

[0040] For example, the signal output unit 21 outputs the measurement signal to the transmission line 51 via the corresponding communication port 30 during a period when the relay unit 10 is not performing relay processing via the transmission line 51 .

[0041] More specifically, the relay unit 10 outputs period information indicating a period during which relay processing via the transmission line 51 is not performed to the processing unit 23 .

[0042] The processing unit 23 receives period information from the relay unit 10, determines a judgment period T1 for performing judgment processing based on the received period information, and outputs a judgment instruction indicating the determined judgment period T1 to the signal output unit 21 and the signal receiving unit 22.

[0043] The signal output unit 21 receives a judgment instruction from the processing unit 23, and when the start time of the judgment period T1 indicated in the received judgment instruction arrives, it outputs a measurement signal to the transmission line 51 via the corresponding communication port 30 until the judgment period T1 expires.

[0044] As an example, the signal output unit 21 outputs a measurement signal that is a sine wave with a frequency f to the transmission line 51. For example, the storage unit 24 stores N digital signals Ds1 obtained by digitally converting a sine wave for multiple cycles. That is, the storage unit 24 stores digital signals Ds1 corresponding to a sine wave with N samples, where N is an integer equal to or greater than 2.

[0045] The signal output unit 21 includes a DA (Digital to Analog) converter. When the start time of the determination period T1 arrives, the signal output unit 21 acquires a digital signal Ds1 from the storage unit 24 at output timings according to the cycle of the operating clock of the DA converter until the determination period T1 expires. Furthermore, the signal output unit 21 outputs a measurement signal of frequency f, which is generated by converting the digital signal Ds1 to analog using the DA converter, to the transmission line 51 via the communication port 30. The signal output unit 21 also outputs the acquired digital signal Ds1 to the processing unit 23. For example, as described below, the frequency f is set according to the length Lc of the transmission line 51.

[0046] The signal output unit 21 may include a signal generating unit such as a DDS (Direct Digital Synthesizer) and output a sine wave generated by the signal generating unit to the transmission line 51 via the communication port 30 .

[0047] (Signal Receiving Unit) The signal receiving unit 22 receives a response signal including a signal resulting from the reflection of the measurement signal from the transmission line 51. That is, the signal receiving unit 22 receives a response signal including the measurement signal output by the signal output unit 21 and a reflected signal resulting from the reflection of the measurement signal from the transmission line 51 via the corresponding communication port 30.

[0048] More specifically, the signal receiving unit 22 receives a judgment instruction from the processing unit 23, and when the start time of the judgment period T1 indicated in the received judgment instruction arrives, it receives a response signal from the transmission line 51 via the corresponding communication port 30 until the judgment period T1 expires.

[0049] The signal receiving unit 22 includes an AD (Analog to Digital) converter. During the determination period T1, the signal receiving unit 22 samples the response signal received from the transmission line 51 using the AD converter, thereby generating a digital signal Ds2 having N samples. The signal receiving unit 22 outputs the generated digital signal Ds2 to the processing unit 23.

[0050] (Processing Unit) The processing unit 23 calculates an evaluation value EV based on the amplitude and phase of the response signal received by the signal receiving unit 22. The processing unit 23 performs a determination process based on the distribution of the calculated evaluation values ​​EV.

[0051] For example, the processing unit 23 calculates the evaluation value EV based on the amplitude and phase of the measurement signal and the amplitude and phase of the reflected signal included in the response signal.

[0052] More specifically, the processing unit 23 generates a digital signal Ds3 indicative of the reflected signal by subtracting the component of the digital signal Ds1 received from the signal output unit 21 from the digital signal Ds2 received from the signal receiving unit 22. Based on the digital signal Ds1 indicative of the measurement signal and the digital signal Ds3 indicative of the reflected signal, the processing unit 23 calculates an evaluation value EV related to a reflection coefficient R, which is the ratio of the reflected signal to the measurement signal, as expressed by the following equation (1).

[0053]

[0054] where V1 is the voltage level of the measurement signal, V2 is the voltage level of the reflected signal, e is Napier's constant, j is the imaginary unit, θ is the phase difference between the measurement signal and the reflected signal, and A is the amplitude ratio obtained by dividing the amplitude of the reflected signal by the amplitude of the measurement signal.

[0055] (Determination Example 1) The processing unit 23 calculates the phase difference θ as the evaluation value EV. More specifically, the processing unit 23 calculates, for example, the phase difference θ for each period of the measurement signal based on the digital signal Ds1 representing the measurement signal and the digital signal Ds3 representing the reflected signal, and stores the calculated phase difference θ in the storage unit 24. The phase difference θ is a value greater than or equal to zero degrees and less than or equal to 360 degrees. The phase difference θ is an example of a second evaluation value.

[0056] For example, the processing unit 23 generates a frequency distribution F1, which is the distribution of the phase difference θ during each determination period T1, and determines whether there is an abnormality in the transmission line 51 based on the generated frequency distribution F1.

[0057] 3 is a diagram illustrating an example of a change over time in a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure. In FIG. 3, the horizontal axis represents the phase difference θ [rad], and the vertical axis represents the frequency. FIG. 3 illustrates frequency distributions F1a, F1b, F1c, and F1d that change over time. The frequency distribution F1a is the frequency distribution F1 of the phase difference θ when no abnormality occurs in the transmission line 51. The frequency distribution F1b is the frequency distribution F1 of the phase difference θ when the transmission line 51 is deteriorated. The frequency distribution F1c is the frequency distribution F1 of the phase difference θ when the deterioration of the transmission line 51 has progressed further. The frequency distribution F1d is the frequency distribution F1 of the phase difference θ when the transmission line 51 is disconnected.

[0058] 3, the average value μ1 of the phase difference θ indicated by the frequency distribution F1 increases with the deterioration of the transmission line 51, and when the transmission line 51 is broken, the average value μ1 takes a value that corresponds to the position of the break. More specifically, the phase difference θ when the transmission line 51 is broken is expressed by the following equation (2):

[0059]

[0060] Here, L is the distance [m] from the end of the transmission line 51 on the repeater device 101 side to the breakage point. L is a value greater than or equal to zero and less than or equal to Lc. c is the speed of light [m / sec]. ε is the relative permittivity of the transmission line 51.

[0061] The average value μ1 may increase or decrease as the transmission line 51 deteriorates, depending on the magnitude relationship between the characteristic impedance Z1 of the transmission line 51 and the load impedance Z2 of the communication device 111.

[0062] More specifically, the reflection coefficient R is expressed by the following equation (3) using the characteristic impedance Z1 and the load impedance Z2.

[0063]

[0064] Deterioration of the transmission line 51 increases the characteristic impedance Z1. Whether the reflection coefficient R increases or decreases when the characteristic impedance Z1 increases determines whether the phase difference θ increases or decreases as the transmission line 51 deteriorates. In the communication system 301, it is assumed that the average value μ1 increases as the transmission line 51 deteriorates.

[0065] 4 is a diagram illustrating another example of the change over time of the frequency distribution F1 generated by the processing unit in the relay device according to the embodiment of the present disclosure. In FIG. 4, the horizontal axis represents the phase difference θ [rad], and the vertical axis represents the frequency. FIG. 4 shows frequency distributions F1a and F1e. The frequency distribution F1e is the frequency distribution F1 of the phase difference θ when the transmission line 51 is short-circuited.

[0066] 4, the average value μ1 indicated by the frequency distribution F1 takes a value corresponding to the short-circuit position when the transmission line 51 is short-circuited. More specifically, the phase difference θsh, which is the phase difference θ when the transmission line 51 is short-circuited, is expressed by the following equation (4).

[0067]

[0068] Here, Lsh is the distance [m] from the end of the transmission line 51 on the repeater device 101 side to the short-circuit position. Lsh is a value equal to or greater than zero and equal to or less than Lc.

[0069] 5 and 6 are diagrams illustrating the correspondence relationship between the phase differences θop and θsh and the distances Lop and Lsh calculated by a processing unit in a relay device according to an embodiment of the present disclosure. In FIGS. 5 and 6, the horizontal axis represents the distance [m] from the end of the transmission line 51 on the relay device 101 side to the abnormality occurrence position, and the vertical axis represents the phase difference θ [rad]. FIG. 5 illustrates the correspondence relationship between the phase differences θop and θsh and the distances Lop and Lsh when the frequency f of the measurement signal is 10 MHz. FIG. 6 illustrates the correspondence relationship between the phase differences θop and θsh and the distances Lop and Lsh when the frequency f of the measurement signal is 1 MHz.

[0070] 5, when the frequency f is 10 MHz, the minimum value of the phase difference θsh is smaller than the maximum value of the phase difference θop. Therefore, when the phase difference θ is θx, for example, it is not possible to determine whether a short circuit has occurred at a position distance L1 from the end of the transmission line 51 on the repeater 101 side, or whether a break has occurred at a position distance L2 from the end of the transmission line 51 on the repeater 101 side.

[0071] 6, when the frequency f is 1 MHz, the minimum value of the phase difference θsh is greater than the maximum value of the phase difference θop. Therefore, it is possible to determine whether a short circuit or an open circuit has occurred in the transmission line 51 depending on the value of the phase difference θ.

[0072] Here, the minimum value of the phase difference θsh is π, and the maximum value of the phase difference θop is when the distance Lop in the above-mentioned formula (2) is equal to the length Lc of the transmission line 51. Therefore, in the relay device 101, in order to determine whether the transmission line 51 is short-circuited or open-circuited, the frequency f of the measurement signal is set to a value that satisfies the following formula (5).

[0073]

[0074] 7 is a diagram illustrating another example of a change over time in the frequency distribution F1 generated by the processing unit in the relay device according to the embodiment of the present disclosure. In FIG. 7, the horizontal axis represents the phase difference θ [rad], and the vertical axis represents the frequency. FIG. 7 shows frequency distributions F1a, F1b, and F1f. The frequency distribution F1f is the frequency distribution F1 of the phase difference θ in a state in which a special abnormality other than deterioration, a short circuit, or a break has occurred in the transmission line 51. An example of a state in which a special abnormality has occurred in the transmission line 51 is a state in which the transmission line 51 is partially broken and the cross section of the partially broken portion repeatedly makes contact and does not make contact.

[0075] 7, the shape of the frequency distribution F1 becomes less symmetrical about the average value μ1 due to the occurrence of a special abnormality in the transmission line 51.

[0076] 3 to 7, the frequency distribution F1 changes when an abnormality occurs in the transmission line 51. Therefore, it is possible to determine whether an abnormality has occurred in the transmission line 51 based on the frequency distribution F1.

[0077] More specifically, after generating the frequency distribution F1, the processing unit 23 performs a determination process based on changes over time in the statistical quantities indicated by the frequency distribution F1. As an example, the processing unit 23 calculates an average value μ1 and a median value m1 of the phase difference θ indicated by the frequency distribution F1 as the statistical quantities indicated by the frequency distribution F1, and performs a determination process based on changes over time in the average value μ1 and the median value m1.

[0078] For example, the storage unit 24 stores a reference distribution Fr1, which is a frequency distribution F1 of the phase difference θ in a state where no abnormality occurs in the transmission line 51, and a reference average value μ1a, which is the average value μ1 indicated by the reference distribution Fr1. The reference distribution Fr1 is generated in advance based on a plurality of phase differences θ calculated before the operation of the communication system 301.

[0079] 8 is a diagram illustrating an example of a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure. In FIG. 8, the horizontal axis represents the phase difference θ [rad], and the vertical axis represents the frequency. Referring to FIG. 8, the processing unit 23 generates the frequency distribution F1 and compares the mean value μ1 indicated by the generated frequency distribution F1 with thresholds T1a and T1b set based on the reference distribution Fr1. The processing unit 23 also compares the mean value μ1 indicated by the frequency distribution F1 with the median m1 indicated by the frequency distribution F1.

[0080] For example, the threshold T1a is a value obtained by subtracting a predetermined value from the reference average value μ1a, and the threshold T1b is a value obtained by adding a predetermined value to the reference average value μ1a. Note that the threshold T1a may be a value obtained by subtracting three times the standard deviation Sy of the reference distribution Fr1 from the reference average value μ1a. Furthermore, the threshold T1b may be a value obtained by adding three times the standard deviation Sy to the reference average value μ1a.

[0081] If the average value μ1 is equal to or greater than the threshold value T1a, equal to or less than the threshold value T1b, and the absolute value D1 of the difference between the average value μ1 and the median value m1 is equal to or less than the predetermined threshold value TD1, the processing unit 23 determines that no abnormality has occurred in the transmission line 51. Then, the processing unit 23 stores the determination result including the average value μ1 in the storage unit 24.

[0082] In addition, the processing unit 23 may calculate other statistical quantities that represent the shape of the frequency distribution F1, such as the maximum value and standard deviation of the phase difference θ indicated by the frequency distribution F1, and use the other calculated statistical quantity, for example, the mode, instead of the median m1.

[0083] 9 is a diagram illustrating another example of a frequency distribution F1 generated by the processing unit of the relay device according to the embodiment of the present disclosure, in which the horizontal axis represents the phase difference θ [rad] and the vertical axis represents the frequency.

[0084] Referring to FIG. 9, the processing unit 23 determines that an abnormality has occurred in the transmission line 51 when the average value μ1 is less than a threshold value T1a or greater than a threshold value T1b.

[0085] In this case, based on the frequency distribution F1, the processing unit 23 further determines the type of abnormality that has occurred in the transmission line 51. For example, the processing unit 23 determines that the type of abnormality that has occurred in the transmission line 51 is a break in the transmission line 51, a short circuit in the transmission line 51, or deterioration of the transmission line 51.

[0086] More specifically, the processing unit 23 compares the average value μ1 with predetermined thresholds T1c, T1d, T1e, and T1f. The threshold T1c is a value obtained by subtracting a predetermined margin from zero, which is the minimum value of the phase difference θop shown in FIG. 6. The threshold T1d is a value obtained by adding a predetermined margin to the maximum value of the phase difference θop shown in FIG. 6. The threshold T1e is a value obtained by subtracting a predetermined margin from π, which is the minimum value of the phase difference θsh shown in FIG. 6. The threshold T1f is a value obtained by adding a predetermined margin to the maximum value of the phase difference θsh shown in FIG. 6.

[0087] If the average value μ1 is equal to or greater than the threshold value T1e and equal to or less than the threshold value T1f, the processing unit 23 determines that the transmission line 51 is short-circuited or deteriorated. Then, the processing unit 23 stores the determination result including the average value μ1 in the storage unit 24.

[0088] On the other hand, if the average value μ1 is equal to or greater than the threshold value T1c and equal to or less than the threshold value T1d, the processing unit 23 determines that the transmission line 51 is broken or deteriorated. Then, the processing unit 23 stores the determination result including the average value μ1 in the storage unit 24.

[0089] On the other hand, if the average value μ1 is less than the threshold value T1c, greater than the threshold value T1d and less than the threshold value T1a, greater than the threshold value T1b and less than the threshold value T1e, or greater than the threshold value T1f, the processing unit 23 determines that the transmission line 51 is degraded. Then, the processing unit 23 stores the determination result including the average value μ1 in the storage unit 24.

[0090] For example, the processing unit 23 determines the degree of deterioration of the transmission line 51 based on the change over time in the average value μ1 indicated by the frequency distribution F1. More specifically, when the processing unit 23 determines that the transmission line 51 is deteriorated, it compares the calculated average value μ1 with the average value μ1 included in a previous determination result. Then, the processing unit 23 determines the degree of deterioration based on the amount of change in the calculated average value μ1 from the average value μ1 included in the previous determination result.

[0091] 10 is a diagram illustrating another example of a frequency distribution F1 generated by a processor in a relay device according to an embodiment of the present disclosure. In FIG. 10, the horizontal axis represents the phase difference θ [rad], and the vertical axis represents the frequency. Referring to FIG. 10, if the absolute value D1 of the difference between the average value μ1 and the median value m1 is greater than the threshold value TD1, the processor 23 determines that a special abnormality has occurred in the transmission line 51. The processor 23 then stores the determination result, including the average value μ1 and the median value m1, in the memory unit 24.

[0092] For example, when the processing unit 23 determines that an abnormality has occurred in the transmission line 51, it notifies the user of the determination result including the type of abnormality via the relay unit 10 and the communication device 111.

[0093] (Variation 1) Based on a change over time in the shape of the frequency distribution F1, the processing unit 23 determines whether there is an abnormality in the transmission line 51. For example, the processing unit 23 determines whether there is an abnormality in the transmission line 51 based on a correlation between the shape of the frequency distribution F1 and the shape of the reference distribution Fr1.

[0094] More specifically, after generating the frequency distribution F1, the processing unit 23 acquires the reference distribution Fr1 from the storage unit 24. Then, the processing unit 23 calculates a correlation coefficient C1 indicating the correlation between the generated frequency distribution F1 and the reference distribution Fr1 according to the following equation (6).

[0095]

[0096] Here, Sxy is the covariance between the frequency distribution F1 and the reference distribution Fr1. Sx is the standard deviation of the frequency distribution F1. Sy is the standard deviation of the reference distribution Fr1. xi is the frequency of the phase difference θi in the frequency distribution F1. yi is the frequency of the phase difference θi in the reference distribution Fr1. n is the number of data points for the phase difference θ that make up the frequency distribution F1 and the number of data points for the phase difference θ that make up the reference distribution Fr1. For example, the phase difference θ in the frequency distribution F1 and the phase difference θ in the reference distribution Fr1 are relative. The phase difference θ in the frequency distribution F1 is corrected so that the position of the tail of the frequency distribution F1 matches the position of the tail of the reference distribution Fr1, or so that the median m1 of the frequency distribution F1 matches the median of the reference distribution Fr1.

[0097] When the correlation coefficient C1 is equal to or greater than a predetermined threshold value TC1, the processing unit 23 determines that no special abnormality has occurred in the transmission line 51. The threshold value TC1 is a value between 0.2 and 1, both inclusive, that is appropriately set depending on the application, and may be, for example, 0.7. On the other hand, when the correlation coefficient C1 is less than the predetermined threshold value TC1, the processing unit 23 determines that a special abnormality has occurred in the transmission line 51.

[0098] Instead of calculating the correlation coefficient C1, the processing unit 23 may perform the determination process based on the change over time in the envelope that represents the shape of the frequency distribution F1. More specifically, the processing unit 23 determines whether or not a special abnormality has occurred in the transmission line 51 based on the result of comparing the envelope that represents the shape of the frequency distribution F1 with the envelope that represents the shape of the reference distribution Fr1.

[0099] (Determination Example 2) The processing unit 23 calculates the amplitude ratio A as the evaluation value EV. More specifically, the processing unit 23 calculates, for example, the amplitude ratio A for each period of the measurement signal based on the digital signal Ds1 representing the measurement signal and the digital signal Ds3 representing the reflected signal, and stores the calculated amplitude ratio A in the storage unit 24. The amplitude ratio A is a value greater than or equal to zero and less than or equal to 1. The amplitude ratio A is an example of a first evaluation value.

[0100] The processing unit 23 generates a frequency distribution F2, which is the distribution of the amplitude ratio A during each determination period T1, and determines whether there is an abnormality in the transmission line 51 based on the generated frequency distribution F2.

[0101] Fig. 11 is a diagram illustrating an example of a change over time in a frequency distribution F2 generated by a processing unit in a relay device according to an embodiment of the present disclosure. In Fig. 11, the horizontal axis represents the amplitude ratio A, and the vertical axis represents the frequency. Fig. 11 shows frequency distributions F2a, F2b, F2c, and F2d. The frequency distribution F2a is the frequency distribution F2 of the amplitude ratio A when no abnormality occurs in the transmission line 51. The frequency distribution F2b is the frequency distribution F2 of the amplitude ratio A when the transmission line 51 is deteriorated. The frequency distribution F2c is the frequency distribution F2 of the amplitude ratio A when the deterioration of the transmission line 51 has progressed further. The frequency distribution F2d is the frequency distribution F2 of the amplitude ratio A when the transmission line 51 is broken.

[0102] 11 , the average value μ2 of the amplitude ratio A indicated by the frequency distribution F2 increases with the deterioration of the transmission line 51, and when the transmission line 51 is broken, the average value μ2 becomes close to 1. Note that the average value μ2 may increase or decrease with the deterioration of the transmission line 51, depending on the magnitude relationship between the characteristic impedance Z1 of the transmission line 51 and the load impedance Z2 of the communication device 111. In the communication system 301, it is assumed that the average value μ2 increases with the deterioration of the transmission line 51.

[0103] 12 is a diagram illustrating another example of the change over time in the frequency distribution F2 generated by the processing unit in the relay device according to the embodiment of the present disclosure. In FIG. 12, the horizontal axis represents the amplitude ratio A, and the vertical axis represents the frequency. FIG. 12 illustrates frequency distributions F2a and F2e. The frequency distribution F2e is the frequency distribution F2 with the amplitude ratio A when the transmission line 51 is short-circuited.

[0104] Referring to FIG. 12, the average value μ2 indicated by the frequency distribution F2 is close to 1 when the transmission line 51 is short-circuited.

[0105] Fig. 13 is a diagram illustrating another example of the change over time in the frequency distribution F2 generated by the processing unit in the relay device according to the embodiment of the present disclosure. In Fig. 13, the horizontal axis represents the amplitude ratio A, and the vertical axis represents the frequency. Fig. 13 shows frequency distributions F2a, F2b, and F2f. The frequency distribution F2f is the frequency distribution F2 of the amplitude ratio A in a state in which a special abnormality has occurred in the transmission line 51.

[0106] 13, the shape of the frequency distribution F2 becomes less symmetrical about the average value μ2 due to the occurrence of a special abnormality in the transmission line 51.

[0107] 11 to 13, the frequency distribution F2 changes when an abnormality occurs in the transmission line 51. Therefore, it is possible to determine whether an abnormality has occurred in the transmission line 51 based on the frequency distribution F2.

[0108] More specifically, after generating the frequency distribution F2, the processing unit 23 performs a determination process based on changes over time in the statistical quantities indicated by the frequency distribution F2. As an example, the processing unit 23 calculates an average value μ2 and a median value m2 of the amplitude ratio A indicated by the frequency distribution F2 as the statistical quantities indicated by the frequency distribution F2, and performs a determination process based on changes over time in the average value μ2 and the median value m2.

[0109] For example, the storage unit 24 stores a reference distribution Fr2, which is a frequency distribution F2 of the amplitude ratio A in a state where no abnormality occurs in the transmission line 51, and a reference average value μ2a, which is the average value μ2 indicated by the reference distribution Fr2. The reference distribution Fr2 is generated in advance based on a plurality of amplitude ratios A calculated before the communication system 301 is put into operation.

[0110] 14 is a diagram illustrating an example of a frequency distribution F2 generated by a processing unit in a relay device according to an embodiment of the present disclosure. In FIG. 14, the horizontal axis represents the amplitude ratio A, and the vertical axis represents the frequency. Referring to FIG. 14, the processing unit 23 generates the frequency distribution F2 and then compares the mean value μ2 indicated by the generated frequency distribution F2 with thresholds T2a and T2b set based on the reference distribution Fr2. The processing unit 23 also compares the mean value μ2 indicated by the frequency distribution F2 with the median value m2 indicated by the frequency distribution F2.

[0111] For example, the threshold T2a is a value obtained by subtracting a predetermined value from the reference average value μ2a, and the threshold T2b is a value obtained by adding a predetermined value to the reference average value μ2a. Note that the threshold T2a may be a value obtained by subtracting three times the standard deviation Sp of the reference distribution Fr2 from the reference average value μ2a. Furthermore, the threshold T2b may be a value obtained by adding three times the standard deviation Sp to the reference average value μ2a.

[0112] If the average value μ2 is equal to or greater than the threshold value T2a, the average value μ2 is equal to or less than the threshold value T2b, and the absolute value D2 of the difference between the average value μ2 and the median value m2 is equal to or less than a predetermined threshold value TD2, the processing unit 23 determines that no abnormality has occurred in the transmission line 51. Then, the processing unit 23 stores the determination result including the average value μ2 in the storage unit 24.

[0113] In addition, the processing unit 23 may calculate other statistical quantities that represent the shape of the frequency distribution F2, such as the maximum value and standard deviation of the amplitude ratio A indicated by the frequency distribution F2, and use the other calculated statistical quantities instead of the median m2.

[0114] 15 is a diagram illustrating another example of a frequency distribution F2 generated by the processing unit in the relay device according to the embodiment of the present disclosure, in which the horizontal axis represents the amplitude ratio A and the vertical axis represents the frequency.

[0115] Referring to FIG. 15, the processing unit 23 determines that an abnormality has occurred in the transmission line 51 when the average value μ2 is less than the threshold value T2a or greater than the threshold value T2b.

[0116] In this case, based on the frequency distribution F2, the processing unit 23 further determines the type of abnormality that has occurred in the transmission line 51. For example, the processing unit 23 determines that the type of abnormality that has occurred in the transmission line 51 is a break or short circuit in the transmission line 51, and deterioration of the transmission line 51.

[0117] More specifically, the processing unit 23 compares the average value μ2 with a predetermined threshold value T2e, which is a value obtained by subtracting a predetermined value from 1.

[0118] If the average value μ2 is equal to or greater than the threshold value T2e, the processing unit 23 determines that the transmission line 51 is short-circuited or disconnected. Then, the processing unit 23 stores the determination result including the average value μ2 in the storage unit 24.

[0119] On the other hand, if the average value μ2 is less than the threshold value T2e, the processing unit 23 determines that the transmission line 51 is deteriorated. Then, the processing unit 23 stores the determination result including the average value μ2 in the storage unit 24.

[0120] For example, the processing unit 23 determines the degree of deterioration of the transmission line 51 based on the change over time in the average value μ2 indicated by the frequency distribution F2. More specifically, when the processing unit 23 determines that the transmission line 51 is deteriorated, it compares the calculated average value μ2 with the average value μ2 included in a previous determination result. Then, the processing unit 23 determines the degree of deterioration based on the amount of change in the calculated average value μ2 from the average value μ2 included in the previous determination result.

[0121] 16 is a diagram illustrating another example of a frequency distribution F2 generated by a processor in a relay device according to an embodiment of the present disclosure. In FIG. 16, the horizontal axis represents the amplitude ratio A, and the vertical axis represents the frequency. Referring to FIG. 16, if the absolute value D2 of the difference between the average value μ2 and the median value m2 is greater than the threshold value TD2, the processor 23 determines that a special abnormality has occurred in the transmission line 51. The processor 23 then stores the determination result, including the average value μ2 and the median value m2, in the memory unit 24.

[0122] (Modification 2) Based on a change over time in the shape of the frequency distribution F2, the processing unit 23 determines whether there is an abnormality in the transmission line 51. For example, the processing unit 23 determines whether there is an abnormality in the transmission line 51 based on a correlation between the shape of the frequency distribution F2 and the shape of the reference distribution Fr2.

[0123] More specifically, after generating the frequency distribution F2, the processing unit 23 acquires the reference distribution Fr2 from the storage unit 24. Then, the processing unit 23 calculates a correlation coefficient C2 indicating the correlation between the generated frequency distribution F2 and the reference distribution Fr2 according to the following equation (7).

[0124]

[0125] Here, Spq is the covariance between the frequency distribution F2 and the reference distribution Fr2. Sp is the standard deviation of the frequency distribution F2. Sq is the standard deviation of the reference distribution Fr2. pi is the frequency of the amplitude ratio Ai in the frequency distribution F2. q is the frequency of the amplitude ratio Ai in the reference distribution Fr2. n is the number of data points for the amplitude ratio A that make up the frequency distribution F2 and the number of data points for the amplitude ratio A that make up the reference distribution Fr2. For example, the amplitude ratio A in the frequency distribution F2 and the amplitude ratio A in the reference distribution Fr2 are relative. The amplitude ratio A in the frequency distribution F2 is corrected so that the position of the tail of the frequency distribution F2 matches the position of the tail of the reference distribution Fr2, or so that the median m2 of the frequency distribution F2 matches the median of the reference distribution Fr2.

[0126] When the correlation coefficient C2 is equal to or greater than a predetermined threshold value TC2, the processing unit 23 determines that no special abnormality has occurred in the transmission line 51. The threshold value TC2 is a value between 0.2 and 1, both inclusive, that is appropriately set depending on the application, and may be, for example, 0.7. On the other hand, when the correlation coefficient C2 is less than the predetermined threshold value TC2, the processing unit 23 determines that a special abnormality has occurred in the transmission line 51.

[0127] Instead of calculating the correlation coefficient C2, the processing unit 23 may perform the determination process based on the change over time in the envelope that represents the shape of the frequency distribution F2. More specifically, the processing unit 23 determines whether or not a special abnormality has occurred in the transmission line 51 based on the result of comparing the envelope that represents the shape of the frequency distribution F2 with the envelope that represents the shape of the reference distribution Fr2.

[0128] For example, the processing unit 23 determines an abnormality in the transmission line 51 based on the frequency distributions F1 and F2. More specifically, the processing unit 23 executes determination example 1 and determination example 2. If it is determined that an abnormality has occurred in the transmission line 51 in at least one of determination example 1 and determination example 2, the processing unit 23 makes an overall determination that an abnormality has occurred in the transmission line 51 and notifies the user of the overall determination result. Note that the processing unit 23 may be configured not to perform either determination example 1 or determination example 2.

[0129] (Modification 3) The processing unit 23 determines the type of abnormality that has occurred in the transmission line 51 based on the frequency distributions F1 and F2.

[0130] 9 and 15 again, in more detail, the processing unit 23 determines that the transmission line 51 is short-circuited if the average value μ1 is equal to or greater than the threshold value T1e, the average value μ1 is equal to or less than the threshold value T1f, and the average value μ2 is equal to or greater than the threshold value T2e.

[0131] On the other hand, if the average value μ1 is equal to or greater than the threshold value T1e, the average value μ1 is equal to or less than the threshold value T1f, and the average value μ2 is less than the threshold value T2e, the processing unit 23 determines that the transmission line 51 is deteriorated.

[0132] Furthermore, if the average value μ1 is equal to or greater than the threshold value T1c, the average value μ1 is equal to or less than the threshold value T1d, and the average value μ2 is equal to or greater than the threshold value T2e, the processing unit 23 determines that the transmission line 51 is broken.

[0133] On the other hand, if the average value μ1 is equal to or greater than the threshold value T1c, the average value μ1 is equal to or less than the threshold value T1d, and the average value μ2 is less than the threshold value T2e, the processing unit 23 determines that the transmission line 51 is deteriorated.

[0134] In this way, by using a configuration that determines the type of abnormality that has occurred in the transmission line 51 based on the frequency distributions F1 and F2, it is possible to determine whether the transmission line 51 is short-circuited or deteriorated, and whether the transmission line 51 is broken or deteriorated.

[0135] 17 is a diagram illustrating another example of a frequency distribution F1 generated by a processing unit in a relay device according to an embodiment of the present disclosure, in which the horizontal axis represents the phase difference θ [rad] and the vertical axis represents the frequency.

[0136] Referring to FIG. 17, the processing unit 23 determines the positions of breaks, deteriorations, and short circuits in the transmission line 51 based on the frequency distribution F1.

[0137] More specifically, when the processing unit 23 determines that the transmission line 51 is broken or deteriorated based on the comparison result between the average value μ1 indicated by the frequency distribution F1 and the threshold values ​​T1c and T1d, the processing unit 23 compares the average value μ1 with the threshold values ​​TA1, TA2, TA3, TA4, and TA5, which are the threshold value TA.

[0138] The threshold value TA is a value equal to or greater than the threshold value T1c and equal to or less than the threshold value T1d. For example, the threshold values ​​TA are values ​​spaced at equal intervals between the threshold values ​​T1c and T1d. That is, the threshold value TA1 is a value obtained by adding a predetermined value M to the threshold value T1c, the threshold value TA2 is a value obtained by adding a predetermined value M to the threshold value TA1, the threshold value TA3 is a value obtained by adding a predetermined value M to the threshold value TA2, the threshold value TA4 is a value obtained by adding a predetermined value M to the threshold value TA3, the threshold value TA5 is a value obtained by adding a predetermined value M to the threshold value TA4, and the threshold value T1d is a value obtained by adding a predetermined value M to the threshold value TA5. Note that the processing unit 23 may compare the average value μ1 with four or fewer threshold values ​​TA or six or more threshold values ​​TA. Furthermore, the threshold values ​​TA do not have to be values ​​spaced at equal intervals between the threshold values ​​T1c and T1d.

[0139] For example, the storage unit 24 stores disconnection position information indicating the correspondence relationship between the threshold value TA and the distance Lo from the end of the transmission line 51 on the repeater 101 side to the disconnection position. The disconnection position information is created in advance based on the relationship between the phase difference θop and the distance Lop shown in FIG. 6 .

[0140] The processing unit 23 identifies the threshold value TA that is closest to the average value μ1 among the five threshold values ​​TA. The processing unit 23 acquires the distance Lo corresponding to the identified threshold value TA from the disconnection position information in the storage unit 24. The processing unit 23 determines that the transmission line 51 is disconnected or deteriorated at the position corresponding to the acquired distance Lo.

[0141] In addition, if the processing unit 23 determines that the transmission line 51 is short-circuited or deteriorated based on the comparison result between the average value μ1 indicated by the frequency distribution F1 and the threshold values ​​T1e and T1f, it compares the average value μ1 with the threshold values ​​TB1, TB2, TB3, TB4, and TB5, which are the threshold values ​​TB.

[0142] The threshold value TB is a value equal to or greater than the threshold value T1e and equal to or less than the threshold value T1f. For example, the threshold values ​​TB are values ​​spaced at equal intervals between the threshold values ​​T1e and T1f. That is, the threshold value TB1 is a value obtained by adding a predetermined value M to the threshold value T1e, the threshold value TB2 is a value obtained by adding a predetermined value M to the threshold value TB1, the threshold value TB3 is a value obtained by adding a predetermined value M to the threshold value TB2, the threshold value TB4 is a value obtained by adding a predetermined value M to the threshold value TB3, the threshold value TB5 is a value obtained by adding a predetermined value M to the threshold value TB4, and the threshold value T1f is a value obtained by adding a predetermined value M to the threshold value TB5. Note that the processing unit 23 may compare the average value μ1 with four or fewer threshold values ​​TB or six or more threshold values ​​TB. Furthermore, the threshold values ​​TB do not have to be values ​​spaced at equal intervals between the threshold values ​​T1e and T1f.

[0143] For example, the storage unit 24 stores short-circuit position information indicating the correspondence relationship between the threshold value TB and the distance Lsh from the end of the transmission line 51 on the relay device 101 side to the short-circuit position. The short-circuit position information is created in advance based on the relationship between the phase difference θsh and the distance Lsh shown in FIG.

[0144] The processing unit 23 identifies the threshold value TB that is closest to the average value μ1 among the five threshold values ​​TB. The processing unit 23 acquires the distance Lsh corresponding to the identified threshold value TB from the short-circuit position information in the storage unit 24. The processing unit 23 determines that the transmission line 51 is short-circuited or deteriorated at the position corresponding to the acquired distance Lsh.

[0145] For example, the processing unit 23 determines the type of abnormality that has occurred in the transmission line 51 based on the frequency distribution F2 in accordance with the above-described third modification. This makes it possible to determine the locations of the break, deterioration, and short circuit in the transmission line 51 while determining whether the transmission line 51 is broken, short, or deteriorated.

[0146] [Operation Flow] FIG. 18 is a flowchart defining an example of an operation procedure when a relay device according to an embodiment of the present disclosure performs a determination process.

[0147] Referring to FIG. 18, first, the relay device 101 waits for the arrival of the determination period T1 (NO in step S11), and when the determination period T1 arrives (YES in step S11), it starts outputting a measurement signal and receiving a response signal (step S12).

[0148] Next, the relay device 101 calculates the phase difference θ and the amplitude ratio A for each period of the measurement signal based on the amplitude and phase of the measurement signal and the amplitude and phase of the reflected signal included in the response signal (step S13).

[0149] Next, the relay device 101 generates a frequency distribution F1 of the phase difference θ during the determination period T1 and a frequency distribution F2 of the amplitude ratio A during the determination period T1 (step S14).

[0150] Next, the relay device 101 performs a determination process based on the frequency distributions F1 and F2 (step S15).

[0151] Next, the relay device 101 stores the determination result including the average values ​​μ1 and μ2 in the storage unit 24 (step S16).

[0152] Next, when the relay device 101 determines that an abnormality has occurred in the transmission line 51, for example, the relay device 101 notifies the user of the determination result via the relay unit 10 and the communication device 111 (step S17).

[0153] Next, the relay device 101 waits for a new determination period T1 to arrive (NO in step S11).

[0154] 19 is a flowchart illustrating an example of an operation procedure when a relay device according to an embodiment of the present disclosure performs a determination process, and is a flowchart illustrating the above-described determination example 1, which shows details of step S15 in FIG.

[0155] Referring to FIG. 19, first, the relay device 101 compares the average value μ1 indicated by the frequency distribution F1 with thresholds T1a and T1b (step S21).

[0156] Next, if the average value μ1 is greater than or equal to the threshold value T1a and less than or equal to the threshold value T1b (YES in step S22), the relay device 101 compares the absolute value D1 of the difference between the average value μ1 and the median value m1 with the threshold value TD1 (step S23).

[0157] Next, if the absolute value D1 is equal to or smaller than the threshold value TD1 (YES in step S24), the relay device 101 determines that no abnormality has occurred in the transmission line 51 (step S25).

[0158] On the other hand, if the absolute value D1 is greater than the threshold value TD1 (NO in step S24), the relay device 101 determines that a special abnormality has occurred in the transmission line 51 (step S26).

[0159] On the other hand, if the average value μ1 is less than the threshold value T1a or greater than the threshold value T1b (NO in step S22), the relay device 101 compares the average value μ1 with the threshold values ​​T1c and T1d (step S27).

[0160] Next, if the average value μ1 is equal to or greater than the threshold value T1c and equal to or less than the threshold value T1d (YES in step S28), the relay device 101 determines that the transmission line 51 is broken or deteriorated (step S29).

[0161] On the other hand, if the average value μ1 is less than the threshold value T1c or greater than the threshold value T1d (NO in step S28), the relay device 101 compares the average value μ1 with the threshold values ​​T1e and T1f (step S30).

[0162] Next, if the average value μ1 is equal to or greater than the threshold value T1e and equal to or less than the threshold value T1f (YES in step S31), the relay device 101 determines that the transmission line 51 is short-circuited or deteriorated (step S32).

[0163] On the other hand, if the average value μ1 is less than the threshold value T1e or greater than the threshold value T1f (NO in step S31), the relay device 101 determines that the transmission line 51 is deteriorated (step S33).

[0164] 20 is a flowchart illustrating an example of an operation procedure when a relay device according to an embodiment of the present disclosure performs a determination process, and is a flowchart illustrating the above-described determination example 2, which shows details of step S15 in FIG.

[0165] Referring to FIG. 20, first, relay device 101 compares mean value μ2 indicated by frequency distribution F2 with thresholds T2a and T2b (step S41).

[0166] Next, if the average value μ2 is greater than or equal to the threshold value T2a and less than or equal to the threshold value T2b (YES in step S42), the relay device 101 compares the absolute value D2 of the difference between the average value μ2 and the median value m2 with the threshold value TD2 (step S43).

[0167] Next, if the absolute value D2 is equal to or smaller than the threshold value TD2 (YES in step S44), the relay device 101 determines that no abnormality has occurred in the transmission line 51 (step S45).

[0168] On the other hand, if the absolute value D2 is greater than the threshold value TD2 (NO in step S44), the relay device 101 determines that a special abnormality has occurred in the transmission line 51 (step S46).

[0169] On the other hand, if the average value μ2 is less than the threshold value T2a or greater than the threshold value T2b (NO in step S42), the relay device 101 compares the average value μ2 with the threshold value T2e (step S47).

[0170] Next, if the average value μ2 is equal to or greater than the threshold value T2e (YES in step S48), the relay device 101 determines that the transmission line 51 is short-circuited or broken (step S49).

[0171] On the other hand, if the average value μ2 is less than the threshold value T2e (NO in step S48), the relay device 101 determines that the transmission line 51 has deteriorated (step S50).

[0172] For example, when determining the type of abnormality that has occurred in the transmission line 51 as in the above-described third modification, the relay device 101 executes the process of the flowchart shown in Fig. 19 and the process of the flowchart shown in Fig. 20. Then, when the relay device 101 determines in step S29 that the transmission line 51 is broken or deteriorated and also determines in step S49 that the transmission line 51 is short-circuited or broken, it comprehensively determines that the transmission line 51 is broken.

[0173] Also, for example, if the relay device 101 determines in step S32 that the transmission line 51 is short-circuited or deteriorated, and also determines in step S49 that the transmission line 51 is short-circuited or broken, it makes an overall determination that the transmission line 51 is short-circuited.

[0174] 19 , when determining the location of a break in the transmission line 51, the relay device 101 compares the average value μ1 with multiple threshold values ​​TA and obtains the distance Lop corresponding to the threshold value TA that is closest to the average value μ1 from the break location information. Then, the relay device 101 determines that the transmission line 51 is broken or has deteriorated at the location corresponding to the obtained distance Lop.

[0175] 19, when determining the location of a short circuit in the transmission line 51, the relay device 101 compares the average value μ1 with a plurality of threshold values ​​TB and obtains the distance Lsh corresponding to the threshold value TB that is closest to the average value μ1 from the short circuit location information. Then, the relay device 101 determines that the transmission line 51 is short-circuited or deteriorated at the location corresponding to the obtained distance Lsh.

[0176] In the communication system 301 according to the embodiment of the present disclosure, the relay device 101 is connected to the communication device 111 in a one-to-one relationship via the transmission line 51, but the present invention is not limited to this. The relay device 101 may be connected to a plurality of communication devices 111 in a one-to-multiple relationship via a bus-type transmission line 51.

[0177] Furthermore, in the communication system 301 according to the embodiment of the present disclosure, the relay device 101 is configured to perform the determination process, but this is not limiting. The determination process may be performed by a device other than the relay device 101 in the communication system 301. Specifically, for example, the communication device 111 may function as the determination device and perform the determination process.

[0178] Furthermore, in the relay device 101 according to the embodiment of the present disclosure, the signal output unit 21 is configured to output a measurement signal to the transmission line 51 during a period when the relay unit 10 is not performing relay processing. However, this is not limited to this. The signal output unit 21 may be configured to output a measurement signal to the transmission line 51 during a period when the relay unit 10 is performing relay processing. In this case, for example, the relay device 101 frequency-division multiplexes the communication signal and the measurement signal. More specifically, the signal output unit 21 generates a measurement signal in a frequency band different from the frequency band of the communication signal transmitted and received by the relay unit 10 and outputs the measurement signal to the transmission line 51.

[0179] Furthermore, in the relay device 101 according to the embodiment of the present disclosure, the signal receiving unit 22 is configured to receive, from the transmission line 51 via the corresponding communication port 30, a response signal including a measurement signal output by the signal output unit 21 and a reflected signal, which is a signal obtained by reflecting the measurement signal. However, this is not limited to this. The signal receiving unit 22 may also be configured to receive a response signal that does not include a measurement signal. In other words, the signal receiving unit 22 may be configured to receive a reflected signal as a response signal. More specifically, for example, the signal output unit 21 outputs the measurement signal to the transmission line 51 via a directional coupler and the communication port 30. The signal receiving unit 22 receives the response signal that does not include the measurement signal from the transmission line 51 via the communication port 30 and the directional coupler.

[0180] Furthermore, in the relay device 101 according to the embodiment of the present disclosure, the processing unit 23 is configured to determine the type of abnormality that has occurred in the transmission line 51, but this is not limiting. In the above-described determination example 1, the processing unit 23 may be configured to determine that an abnormality has occurred in the transmission line 51 when the average value μ1 is less than the threshold value T1a or greater than the threshold value T1b, but not to determine the type of abnormality. In the above-described determination example 2, the processing unit 23 may be configured to determine that an abnormality has occurred in the transmission line 51 when the average value μ2 is less than the threshold value T2a or greater than the threshold value T2b, but not to determine the type of abnormality.

[0181] Furthermore, in the relay device 101 according to the embodiment of the present disclosure, the processing unit 23 is configured to determine whether the type of abnormality occurring in the transmission line 51 is a break in the transmission line 51, a short circuit in the transmission line 51, or deterioration of the transmission line 51. However, this is not limiting. The processing unit 23 may be configured to determine a special abnormality in the transmission line 51 without determining whether the type of abnormality occurs in the transmission line 51 is a break in the transmission line 51, a short circuit in the transmission line 51, or deterioration of the transmission line 51.

[0182] Furthermore, in the relay device 101 according to the embodiment of the present disclosure, the processing unit 23 is configured to calculate the phase difference θ and the amplitude ratio A as the evaluation value EV and perform the determination process based on the frequency distributions F1 and F2, but this is not limiting. The processing unit 23 may be configured to calculate the impedance, reactance, or resistance of the transmission line 51 as the evaluation value EV instead of the phase difference θ and the amplitude ratio A, and perform the determination process based on the distribution of the calculated evaluation values ​​EV.

[0183] Furthermore, in the relay device 101 according to the embodiment of the present disclosure, the processing unit 23 is configured to calculate the evaluation value EV, but this is not limited thereto. The processing unit 23 may be configured to obtain the amplitude of the reflected signal from the digital signal Ds3 as the evaluation value EV and perform a determination process based on the distribution of the obtained amplitude. The processing unit 23 may also be configured to obtain the phase of the reflected signal from the digital signal Ds3 as the evaluation value EV and perform a determination process based on the distribution of the obtained phase.

[0184] In the relay device 101 according to the embodiment of the present disclosure, the processing unit 23 is configured to generate the digital signal Ds3 indicating the reflected signal by subtracting the digital signal Ds1 from the digital signal Ds2, but this is not limited to this. The signal receiving unit 22 may be configured to receive the measurement signal from the signal output unit 21, subtract the measurement signal from the received response signal to generate an analog signal indicating the reflected signal, and digitally convert the generated analog signal to generate the digital signal Ds3 and output it to the processing unit 23.

[0185] The above-described embodiments should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0186] Each process (each function) in the above-described embodiments is realized by a processing circuit (circuitry) including one or more processors. The processing circuit may be configured as an integrated circuit or the like that combines one or more memories, various analog circuits, and various digital circuits in addition to the one or more processors. The one or more memories store programs (instructions) that cause the one or more processors to execute each of the processes. The one or more processors may execute each of the processes according to the program read from the one or more memories, or may execute each of the processes according to a logic circuit designed in advance to execute each of the processes. The processor may be any of various processors suitable for computer control, such as a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), and an ASIC (Application Specific Integrated Circuit). Note that the physically separated processors may cooperate with each other to execute the processes. For example, the processors installed in the physically separated computers may cooperate with each other via a network such as a LAN (Local Area Network), a WAN (Wide Area Network), or the Internet to execute the processes. The program may be installed into the memory from an external server device or the like via the network, or may be distributed in a state stored on a recording medium such as a CD-ROM (Compact Disc Read Only Memory), a DVD-ROM (Digital Versatile Disc Read Only Memory), or a semiconductor memory, and then installed into the memory from the recording medium.

[0187] The above description includes the following additional features: [Additional Note 1] A determination device comprising: a signal output unit that outputs a measurement signal having a frequency component to a transmission line; a signal receiving unit that receives from the transmission line a response signal that includes a signal resulting from reflection of the measurement signal; an acquisition unit that acquires a plurality of evaluation values ​​based on at least one of the amplitude and the phase of the response signal received by the signal receiving unit; and a determination unit that determines an abnormality in the transmission line based on a distribution of the evaluation values ​​acquired by the acquisition unit, wherein the determination unit determines a degree of deterioration of the transmission line based on a change in the distribution over time.

[0188] [Supplementary Note 2] A determination device comprising a processing circuit, wherein the processing circuit outputs a measurement signal having frequency components to a transmission line, receives a response signal from the transmission line including a signal resulting from reflection of the measurement signal, obtains a plurality of evaluation values ​​based on at least one of the amplitude and phase of the received response signal, and determines an abnormality in the transmission line based on a distribution of the obtained evaluation values.

[0189] 10 Relay unit 20 Determination processing unit 21 Signal output unit 22 Signal receiving unit 23 Processing unit (acquisition unit, determination unit) 24 Storage unit 30 Communication port 51 Transmission line 101 Relay device 111 Communication device 301 Communication system F1, F1a, F1b, F1c, F1d, F1e, F1f, F2, F2a, F2b, F2c, F2d, F2e, F2f Frequency distribution

Claims

1. a signal output unit that outputs a measurement signal having a frequency component to a transmission line; a signal receiving unit that receives a response signal including a signal obtained by reflecting the measurement signal from the transmission line; an acquisition unit that acquires a plurality of evaluation values ​​based on at least one of the amplitude and the phase of the response signal received by the signal receiving unit; a determination unit that determines whether or not there is an abnormality in the transmission line based on the distribution of the evaluation values ​​acquired by the acquisition unit.

2. The determination device according to claim 1 , wherein the determination unit determines whether the transmission line has an abnormality based on a change over time in a statistical quantity indicated by the distribution.

3. The determination device according to claim 1 , wherein the determination unit determines whether the transmission line has an abnormality based on a correlation between the distribution and a predetermined distribution. 。

4. The determination device according to claim 1 , wherein the determination unit further determines a type of abnormality that has occurred in the transmission line based on the distribution.

5. 5. The determination device according to claim 4, wherein the determination unit determines at least one of a break in the transmission line, a short circuit in the transmission line, and deterioration of the transmission line as the type of abnormality that has occurred in the transmission line.

6. the acquisition unit acquires a first evaluation value that is the evaluation value based on the amplitude and a second evaluation value that is the evaluation value based on the phase; The determination device according to claim 1 , wherein the determination unit determines whether or not an abnormality exists in the transmission line based on a distribution of the first evaluation value and a distribution of the second evaluation value.

7. 7. The determination device according to claim 6, wherein the determination unit determines, based on the distribution of the first evaluation value and the distribution of the second evaluation value, that the type of abnormality that has occurred in the transmission line is a break in the transmission line, a short circuit in the transmission line, or deterioration of the transmission line.

8. The determination device according to claim 6 , wherein the determination unit determines a position of an abnormality that has occurred in the transmission line based on a distribution of the second evaluation values.

9. outputting a measurement signal having a frequency component onto a transmission line; receiving a response signal from the transmission line, the response signal including a signal resulting from reflection of the measurement signal; obtaining a plurality of evaluation values ​​based on at least one of the amplitude and the phase of the received response signal; determining whether or not there is an abnormality in the transmission line based on the distribution of the acquired evaluation values.