Detection device, detection method, and detection program

Abstract

This detection device is provided corresponding to a signal transmission device that receives a received signal via a transmission line and has an adaptive filter applied to the received signal. The detection device comprises an acquisition unit that acquires a filter coefficient of the adaptive filter, and a detection unit that detects any abnormality in the transmission line on the basis of the amount of change in the filter coefficient over time acquired by the acquisition unit.

Description

[Technical Field]

[0001] The present disclosure relates to a detection device, a detection method, and a detection program. This application claims priority based on Japanese Patent Application No. 2021-82440, filed on May 14, 2021, the disclosure of which is incorporated herein in its entirety. [Background technology]

[0002] Patent Document 1 discloses a relay device having a function for detecting disconnection of a signal line provided in a communication cable. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-142862 Summary of the Invention

[0004] The detection device disclosed herein is a detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies it to the received signal, and includes an acquisition unit that acquires a filter coefficient of the adaptive filter, and a detection unit that detects an abnormality in the transmission line based on the amount of change over time in the filter coefficient acquired by the acquisition unit.

[0005] The detection method disclosed herein is a detection method in a detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies the adaptive filter to the received signal, and includes a step of acquiring a filter coefficient of the adaptive filter, and a step of detecting an abnormality in the transmission line based on an amount of change over time in the acquired filter coefficient.

[0006] The detection program disclosed herein is a detection program used in a detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies it to the received signal, and is a program that causes a computer to function as an acquisition unit that acquires the filter coefficients of the adaptive filter and a detection unit that detects an abnormality in the transmission line based on the amount of change over time in the filter coefficients acquired by the acquisition unit. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of a communication system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating another example of the configuration of a communication system according to an embodiment of the present disclosure. [Figure 3] FIG. 3 is a diagram illustrating an example of a configuration of a signal transmission device in a communication system according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of a baseline wander correction unit in a signal transmission device according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a diagram illustrating an example of a configuration of an equalizer in a signal transmission device according to an embodiment of the present disclosure. [Figure 6] FIG. 6 is a diagram illustrating an example of the configuration of an echo canceller in a signal transmission device according to an embodiment of the present disclosure. [Figure 7] FIG. 7 is a diagram illustrating an example of a configuration of a detection device according to an embodiment of the present disclosure. [Figure 8] FIG. 8 is a diagram illustrating an example of time-series data stored in a storage unit of a detection device according to an embodiment of the present disclosure. [Figure 9] FIG. 9 is a diagram illustrating another example of time-series data in the storage unit of the detection device according to the embodiment of the present disclosure. [Figure 10] FIG. 10 is a diagram illustrating another example of time-series data in the storage unit of the detection device according to the embodiment of the present disclosure. [Figure 11]FIG. 11 is a diagram illustrating the time constants of the variable filter units and the detection sensitivities for various abnormalities in the detection device according to the embodiment of the present disclosure. [Figure 12] FIG. 12 is a diagram illustrating a correspondence relationship between a determination result regarding a filter coefficient in a detection process of a detection device according to an embodiment of the present disclosure and a result of the detection process. [Figure 13] FIG. 13 is a flowchart illustrating an example of an operation procedure when the detection device according to the embodiment of the present disclosure performs the detection process. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Problem to be solved by this disclosure] Conventionally, techniques for detecting abnormalities in transmission lines have been developed.

[0009] There is a need for a technology that goes beyond the technology described in Patent Document 1 and that is capable of detecting abnormalities in transmission lines more accurately.

[0010] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a detection device, a detection method, and a detection program that are capable of more accurately detecting abnormalities in transmission lines.

[0011] [Effects of this disclosure] According to the present disclosure, abnormalities in a transmission line can be detected more accurately.

[0012] One aspect of the present disclosure may be realized as a semiconductor integrated circuit that implements part or all of a detection device, or as a detection system including a detection device.

[0013] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0014] (1) A detection device according to an embodiment of the present disclosure is a detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies the received signal to the signal, and includes an acquisition unit that acquires a filter coefficient of the adaptive filter, and a detection unit that detects an abnormality in the transmission line based on the amount of change over time in the filter coefficient acquired by the acquisition unit.

[0015] With this configuration, it is possible to detect an abnormality in the transmission line based on the amount of change over time (the tendency of change) of the filter coefficient, so that, compared to a configuration that simply uses the change over time of the filter coefficient, it is possible to detect an abnormality in the transmission line early and accurately even if the change in the filter coefficient is small. Therefore, it is possible to detect an abnormality in the transmission line more accurately.

[0016] (2) The acquisition unit may acquire the filter coefficients of each of the adaptive filters corresponding to one of the transmission lines, and the detection unit may detect an abnormality in the transmission line based on the amount of change over time of each of the filter coefficients acquired by the acquisition unit.

[0017] With this configuration, various abnormalities in the transmission line can be detected more accurately based on the amount of change over time in the filter coefficients of a plurality of adaptive filters.

[0018] (3) The time constants of the plurality of adaptive filters may be different from one another.

[0019] The changes that appear in the amount of change over time in the filter coefficients for each time constant of the adaptive filter differ depending on the type of abnormality that has occurred. With this configuration, it is possible to estimate the type of abnormality that has occurred based on the amount of change over time in the filter coefficients of each adaptive filter.

[0020] (4) The acquisition unit may acquire the filter coefficients of a plurality of taps in the adaptive filter, each of which corresponds to one of the transmission lines, and the detection unit may detect an abnormality in the transmission line based on the amount of change over time of each of the filter coefficients acquired by the acquisition unit.

[0021] With this configuration, various abnormalities in the transmission line can be detected more accurately based on the amount of change over time in the filter coefficient for each tap.

[0022] (5) The detection unit may detect an abnormality in the transmission line based on the amount of change over time in the increasing direction of the filter coefficient, and may detect an abnormality in the transmission line based on the amount of change over time in the decreasing direction of the filter coefficient.

[0023] In this way, by monitoring both the increasing and decreasing trends of the filter coefficient, various abnormalities in the transmission line can be detected more accurately.

[0024] (6) The acquisition unit may acquire a baseline wander correction coefficient as the filter coefficient of the adaptive filter. Department , the filter coefficients of at least one of the equalizer and the echo canceller may be obtained.

[0025] (7) The acquisition unit may acquire a baseline wander correction coefficient as the filter coefficient of the plurality of adaptive filters. Department , three filter coefficients of the equalizer and the echo canceller may be obtained.

[0026] (8) The detection unit may determine that there is an abnormality in the transmission line when it determines that at least two of the three filter coefficients acquired by the acquisition unit are abnormal values.

[0027] With this configuration, it is possible to more accurately detect abnormalities in the transmission line by utilizing the filter coefficients of various adaptive filters for correcting the received signal.

[0028] (9) The detection unit may determine that the transmission line is abnormal if the number of differences that satisfy the abnormality determination condition is equal to or greater than a predetermined value, or may determine that the transmission line is normal if the number of differences that satisfy the abnormality determination condition is less than a predetermined value, and the abnormality determination condition may be determined using a threshold value of the amount of change over time.

[0029] In this way, by using the abnormality determination conditions to perform abnormality determination, various abnormalities in the transmission line can be detected more accurately.

[0030] (10) A detection method according to an embodiment of the present disclosure is a detection method in a detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies the received signal, and includes a step of acquiring a filter coefficient of the adaptive filter, and a step of detecting an abnormality in the transmission line based on a change in the acquired filter coefficient over time.

[0031] This method makes it possible to detect an abnormality in a transmission line based on the amount of change over time (the tendency of change) of the filter coefficient, so that, compared to a configuration that simply uses the change over time of the filter coefficient, an abnormality in the transmission line can be detected early and accurately even if the change in the filter coefficient is small. Therefore, an abnormality in the transmission line can be detected more accurately.

[0032] (11) A detection program according to an embodiment of the present disclosure is a detection program used in a detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies the received signal, and is a program for causing a computer to function as an acquisition unit that acquires a filter coefficient of the adaptive filter and a detection unit that detects an abnormality in the transmission line based on the amount of change over time in the filter coefficient acquired by the acquisition unit.

[0033] With this configuration, it is possible to detect an abnormality in the transmission line based on the amount of change over time (the tendency of change) of the filter coefficient, so that, compared to a configuration that simply uses the change over time of the filter coefficient, it is possible to detect an abnormality in the transmission line early and accurately even if the change in the filter coefficient is small. Therefore, it is possible to detect an abnormality in the transmission line more accurately.

[0034] 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.

[0035] [Configuration and basic operation] [Communication Systems] 1 is a diagram illustrating an example of a configuration of a communication system according to an embodiment of the present disclosure. Referring to FIG. 1, a communication system 301 includes two signal transmission devices 201 and two detection devices 101. The network topology of the communication system 301 is, for example, a line network topology.

[0036] Two signal transmission devices 201 are connected to each other via a transmission line 1. The transmission line 1 is, for example, an Ethernet (registered trademark) cable. The transmission line 1 includes a cable portion 1A and connector portions 1B provided at first and second ends of the cable portion 1A. The connector section 1B is connected to a connector section (not shown) of the signal transmission device 201. The signal transmission device 201 transmits and receives signals via the transmission line 1.

[0037] The detection device 101 is provided corresponding to the signal transmission device 201. More specifically, the detection device 101 is connected to the signal transmission device 201. The detection device 101 detects an abnormality in the transmission line 1.

[0038] The communication system 301 may be configured to include three or more signal transmission devices 201 and three or more detection devices 101. In this case, the network topology of the communication system 301 is, for example, a star-type network topology. More specifically, a signal transmission device 201 functioning as a relay device and a plurality of signal transmission devices 201 are connected to each other via a transmission line 1.

[0039] 2 is a diagram illustrating another example of the configuration of a communication system according to an embodiment of the present disclosure. Referring to FIG. 2, a communication system 302 includes six signal transmission devices 201 and six detection devices 101. The network topology of the communication system 302 is, for example, a bus-type network topology.

[0040] The signal transmission device 201 is connected to a plurality of (remaining five) signal transmission devices 201 via a transmission line 1. The transmission line 1 is, for example, a bus conforming to the CAN (Controller Area Network) standard. The transmission line 1 includes a cable portion 1A including a plurality of branch lines and a connector portion 1B provided at the tip of each branch line. The connector portion 1B is connected to a connector portion (not shown) of the signal transmission device 201. A first end of the cable portion 1A is connected to a termination resistor R1, and a second end of the cable portion 1A is connected to a termination resistor R2. The signal transmission device 201 transmits and receives signals via the transmission line 1.

[0041] The detection device 101 is provided corresponding to the signal transmission device 201. More specifically, the detection device 101 is connected to the signal transmission device 201. The detection device 101 detects an abnormality in the transmission line 1.

[0042] The communication system 302 may be configured to include two, three, four, five, seven or more signal transmission devices 201.

[0043] Furthermore, the communication systems 301 and 302 may be configured to include fewer detection devices 101 than the number of signal transmission devices 201. In this case, at least one of the multiple signal transmission devices 201 does not need to be connected to the detection device 101.

[0044] The communication systems 301 and 302 are mounted on vehicles, for example, and may also be used in home networks or factory automation.

[0045] In the communication systems 301 and 302, the signal transmission device 201 is a programmable logic controller (PLC), an on-board electronic control unit (ECU), an actuator, or a sensor. The on-board ECU functions as a control device that controls the actuator based on the measurement results of the sensor, for example.

[0046] [Signal transmission device] 3 is a diagram illustrating an example of a configuration of a signal transmission device in a communication system according to an embodiment of the present disclosure. Referring to FIG. 3, the signal transmission device 201 includes a transceiver 21, an analog-to-digital converter (ADC) 22, a digital-to-analog converter (DAC) 23, a processing unit 24, a baseline wander correction unit 30, an equalizer 40, and an echo canceller 50. The baseline wander correction unit 30, the equalizer 40, and the echo canceller 50 are examples of adaptive filters applied to a received signal. The transceiver 21 is connected to the transceiver 21 of another signal transmission device 201 via a transmission line 1.

[0047] The processing unit 24 generates various types of information to be transmitted to the other signal transmission device 201 , and outputs a digital signal including the generated information to the DAC 23 and the echo canceller 50 .

[0048] The DAC 23 converts the digital signal received from the processing unit 24 into an analog signal and outputs it to the transmitting / receiving unit 21 .

[0049] The transmitting / receiving unit 21 transmits the analog signal received from the DAC 23 to another signal transmission device 201 via the transmission line 1 .

[0050] The transmitting / receiving unit 21 also receives an analog signal from another signal transmission device 201 via the transmission line 1 and outputs the received analog signal to the baseline wander correction unit 30 .

[0051] The baseline wander correction unit 30 corrects the analog signal received from the transmitting / receiving unit 21 . More specifically, the analog signal that the transceiver 21 receives from the other signal transmission device 201 may contain a deviation in baseline, i.e., a DC offset, due to a direct current component and a low frequency component. For example, in order to reduce the deviation in baseline of the analog signal that the transceiver 21 receives from the other signal transmission device 201, the baseline wander correction unit 30 receives a digital signal from the ADC 22 as described below, and corrects the analog signal received from the transceiver 21 using the received digital signal as a reference signal. The baseline wander correction unit 30 outputs the corrected analog signal to the ADC 22. Details of the baseline wander correction unit 30 will be described later.

[0052] The ADC 22 converts the analog signal received from the baseline wander correction unit 30 into a digital signal and outputs it to the baseline wander correction unit 30 and the equalizer 40 .

[0053] The equalizer 40 corrects the digital signal received from the ADC 22. More specifically, the analog signal received by the transmitter / receiver 21 from the other signal transmission device 201 may have attenuated high-frequency components depending on the length of the transmission line 1, etc. For example, in order to compensate for the attenuation of the analog signal on the transmission line 1, the equalizer 40 performs a correction to increase the level of the high-frequency band of the signal waveform represented by the digital signal received from the ADC 22. The equalizer 40 outputs the corrected digital signal to the echo canceller 50. Details of the equalizer 40 will be described later.

[0054] The echo canceller 50 corrects the digital signal received from the equalizer 40. More specifically, the analog signal received by the transmitter / receiver 21 from another signal transmission device 201 may contain a reflected signal, which is a reflection of the analog signal transmitted from the transmitter / receiver 21 to the other signal transmission device 201. For example, in order to reduce the influence of the reflected signal in the analog signal received by the transmitter / receiver 21, the echo canceller 50 generates a cancellation signal using the digital signal received from the processing unit 24, and corrects the signal waveform represented by the digital signal received from the equalizer 40 using the generated cancellation signal. The echo canceller 50 outputs the corrected digital signal to the processing unit 24. Details of the echo canceller 50 will be described later.

[0055] The processing unit 24 receives the digital signal from the echo canceller 50 and performs predetermined processing using the received digital signal.

[0056] 4 is a diagram illustrating an example of the configuration of a baseline wander correction unit in a signal transmission device according to an embodiment of the present disclosure. Referring to FIG. 4, the baseline wander correction unit 30 includes a variable filter unit 31, a filter calculation unit 32, and a subtractor 33. The variable filter unit 31 has L taps tp1, where L is an integer equal to or greater than 2. Hereinafter, the filter coefficient of the tap tp1 in the variable filter unit 31 will also be referred to as the "filter coefficient h1," and the filter coefficient h1 of the x-th tap tp1 in the variable filter unit 31 will also be referred to as the "filter coefficient h1x." x is an integer equal to or greater than 1 and equal to or less than L.

[0057] The subtractor 33 receives an analog signal from the transmitter / receiver 21. As will be described later, the subtractor 33 also receives an analog signal output from the variable filter unit 31. The subtractor 33 performs subtraction processing to subtract the analog signal received from the variable filter unit 31 from the analog signal received from the transmitter / receiver 21, and outputs the analog signal after the subtraction processing to the ADC 22 and the variable filter unit 31 as a corrected analog signal.

[0058] The variable filter unit 31 receives the analog signal from the subtractor 33 , filters the received analog signal, and outputs the filtered signal to the subtractor 33 .

[0059] The filter calculation unit 32 receives the digital signal from the ADC 22 and uses the received digital signal as a reference signal to set a filter coefficient h1 for each tap tp1 in the variable filter unit 31. More specifically, the filter calculation unit 32 updates the filter coefficient h1 for each tap tp1 in the variable filter unit 31 at an update timing according to a predetermined cycle T1 so that the level of the DC component of the signal waveform represented by the digital signal received from the ADC 22 approaches a predetermined target value.

[0060] 5 is a diagram illustrating an example of the configuration of an equalizer in a signal transmission device according to an embodiment of the present disclosure. Referring to FIG. 5, equalizer 40 includes a variable filter unit 41 and a filter calculation unit 42. Variable filter unit 41 has M taps tp2, where M is an integer equal to or greater than 2. Hereinafter, the filter coefficient of tap tp2 in variable filter unit 41 will also be referred to as "filter coefficient h2," and the filter coefficient h2 of tap tp2 in the y-th stage in variable filter unit 41 will also be referred to as "filter coefficient h2y." y is an integer equal to or greater than 1 and equal to or less than M.

[0061] The variable filter unit 41 receives the digital signal from the ADC 22, filters the signal waveform represented by the received digital signal, and outputs the filtered digital signal to the echo canceller 50 and the filter calculation unit 42 as a corrected digital signal.

[0062] The filter calculation unit 42 receives the digital signal from the variable filter unit 41 and uses the received digital signal as a reference signal to set the filter coefficient h2 of each tap tp2 in the variable filter unit 41. More specifically, the filter calculation unit 42 updates the filter coefficient h2 of each tap tp2 in the variable filter unit 41 at an update timing according to the period T1 so that the level of the high-frequency band of the signal waveform represented by the digital signal received from the variable filter unit 41 approaches a predetermined target value.

[0063] 6 is a diagram illustrating an example of the configuration of an echo canceller in a signal transmission device according to an embodiment of the present disclosure. Referring to FIG. 6, an echo canceller 50 includes a variable filter unit 51, a filter calculation unit 52, and a subtractor 53. The variable filter unit 51 has N taps tp3, where N is an integer equal to or greater than 2. Hereinafter, the filter coefficient of the tap tp3 in the variable filter unit 51 will also be referred to as a "filter coefficient h3," and 51 The filter coefficient h3 of the z-th tap tp3 in is also referred to as a “filter coefficient h3z.” z is an integer greater than or equal to 1 and less than or equal to N.

[0064] The subtractor 53 receives the digital signal from the equalizer 40. As will be described later, the subtractor 53 also receives the digital signal output from the variable filter unit 51. The subtractor 53 performs subtraction processing to subtract the signal waveform represented by the digital signal received from the variable filter unit 51 from the signal waveform represented by the digital signal received from the equalizer 40, and outputs the digital signal after the subtraction processing to the processing unit 24 and the filter calculation unit 52 as a corrected digital signal.

[0065] The variable filter unit 51 receives a digital signal from the processing unit 24 , filters the signal waveform represented by the received digital signal, and outputs the filtered signal to the subtractor 53 .

[0066] The filter calculation unit 52 receives the digital signal from the subtractor 53 and uses the received digital signal as a reference signal to set the filter coefficient h3 of each tap tp3 in the variable filter unit 51. More specifically, the filter calculation unit 52 updates the filter coefficient h3 of each tap tp3 in the variable filter unit 51 at an update timing according to the period T1 so that the level of the reflected signal component included in the signal waveform represented by the digital signal received from the subtractor 53 approaches a predetermined target value.

[0067] [Detection device] 7 is a diagram illustrating an example of a configuration of a detection device according to an embodiment of the present disclosure. Referring to FIG. 7, detection device 101 includes an acquisition unit 11, a storage unit 12, and a detection unit 13. Acquisition unit 11 and detection unit 13 are implemented by processors such as a CPU (Central Processing Unit) and a DSP (Digital Signal Processor). Storage unit 12 is, for example, a non-volatile memory.

[0068] <Acquisition part> The acquisition unit 11 acquires filter coefficients of the adaptive filters. For example, the acquisition unit 11 acquires a filter coefficient h1 of the baseline wander correction unit 30, a filter coefficient h2 of the equalizer 40, and a filter coefficient h3 of the echo canceller 50 as filter coefficients of the adaptive filters corresponding to one transmission line 1.

[0069] For example, the acquisition unit 11 acquires the filter coefficients h1 of the L taps tp1 in the variable filter unit 31 of the baseline wander correction unit 30. More specifically, the acquisition unit 11 monitors the filter calculation unit 32 in the baseline wander correction unit 30, and upon detecting that the filter coefficient h1 of each tap tp1 has been updated by the filter calculation unit 32 at an update timing according to the period T1, acquires the updated filter coefficient h1 of each tap tp1. The acquisition unit 11 stores the acquired filter coefficients h1 in the storage unit 12.

[0070] 8 is a diagram illustrating an example of time-series data stored in a storage unit of a detection device according to an embodiment of the present disclosure. Fig. 8 illustrates time-series data Dt1 of a filter coefficient h1. Referring to Fig. 8, the acquisition unit 11 acquires L filter coefficients h11 to h1L from the first tap tp1 to the Lth tap tp1 in the variable filter unit 31 at each update timing of the filter coefficient h1, and adds the acquired filter coefficients h11 to h1L to the time-series data Dt1 stored in the storage unit 12, thereby updating the time-series data Dt1.

[0071] Furthermore, for example, the acquisition unit 11 acquires the filter coefficients h2 of the M taps tp2 in the variable filter unit 41 of the equalizer 40. More specifically, the acquisition unit 11 monitors the filter calculation unit 42 in the equalizer 40, and upon detecting that the filter coefficient h2 of each tap tp2 has been updated by the filter calculation unit 42 at an update timing according to the period T1, acquires the filter coefficient h2 of each tap tp2 after the update. The acquisition unit 11 stores the acquired filter coefficients h2 in the storage unit 12.

[0072] 9 is a diagram illustrating another example of time-series data stored in a storage unit of a detection device according to an embodiment of the present disclosure. Fig. 9 illustrates time-series data Dt2 of a filter coefficient h2. Referring to Fig. 9, the acquisition unit 11 acquires M filter coefficients h21 to h2M from the first tap tp2 to the Mth tap tp2 in the variable filter unit 41 at each update timing of the filter coefficient h2, and adds the acquired filter coefficients h21 to h2M to the time-series data Dt2 stored in the storage unit 12, thereby updating the time-series data Dt2.

[0073] Furthermore, for example, the acquisition unit 11 acquires the filter coefficients h3 of the N taps tp3 in the variable filter unit 51 of the echo canceller 50. More specifically, the acquisition unit 11 monitors the filter calculation unit 52 in the echo canceller 50, and upon detecting that the filter coefficient h3 of each tap tp3 has been updated by the filter calculation unit 52 at the update timing according to the cycle T1, acquires the filter coefficient h3 of each tap tp3 after the update. The acquisition unit 11 stores the acquired filter coefficients h3 in the storage unit 12.

[0074] 10 is a diagram illustrating another example of time-series data stored in a storage unit of a detection device according to an embodiment of the present disclosure. Fig. 10 illustrates time-series data Dt3 of a filter coefficient h3. Referring to Fig. 10, the acquisition unit 11 acquires N filter coefficients h31 to h3N from the first tap tp3 to the Nth tap tp3 in the variable filter unit 51 at each update timing of the filter coefficient h3, and adds the acquired filter coefficients h31 to h3N to the time-series data Dt3 stored in the storage unit 12 to update the time-series data Dt3. The acquisition unit 11 may acquire the filter coefficients of the adaptive filter over time.

[0075] <Detection unit> The detection unit 13 performs a detection process to detect an abnormality in the transmission line 1 based on the filter coefficients h1, h2, and h3 acquired by the acquisition unit 11. More specifically, when the acquisition unit 11 stores the filter coefficients h1, h2, and h3 in the storage unit 12 at a timing according to the period T1, the detection unit 13 performs the detection process based on the filter coefficients h1, h2, and h3 stored in the storage unit 12.

[0076] (Detection process using filter coefficient h1 of the baseline wander correction unit) (Detection example 1) When the acquisition unit 11 stores L filter coefficients h1 in the storage unit 12 at a timing according to the cycle T1, the detection unit 13 calculates an average value E1 of the L filter coefficients h1.

[0077] For example, an upper threshold EU1 and a lower threshold EL1 for the average value E1 are stored in the storage unit 12. The upper threshold EU1 and the lower threshold EL1 are set in advance based on the distribution of the average value E1, for example.

[0078] Each time the detection unit 13 calculates the average value E1, it compares the calculated average value E1 with an upper threshold value EU1 and a lower threshold value EL1. If the calculated average value E1 is equal to or greater than the lower threshold value EL1 and equal to or less than the upper threshold value EU1, the detection unit 13 determines that no abnormality has occurred in the transmission line 1. On the other hand, if the calculated average value E1 is less than the lower threshold value EL1 or greater than the upper threshold value EU1, the detection unit 13 determines that an abnormality has occurred in the transmission line 1.

[0079] (Detection example 2) The detection unit 13 performs detection processing based on the amount of change over time of the filter coefficient h1. For example, the detection unit 13 performs detection processing by comprehensively determining the amount of change over time of L filter coefficients h1 corresponding to L taps tp1 in the variable filter unit 31 of the baseline wander correction unit 30.

[0080] More specifically, when the acquisition unit 11 updates the time series data Dt1 at a timing according to the period T1, the detection unit 13 calculates an average value A1 of multiple filter coefficients h1 corresponding to the most recent multiple update timings for each tap tp1 in the variable filter unit 31. That is, the detection unit 13 calculates L average values ​​A1 corresponding to the L taps tp1, respectively.

[0081] Then, the detection unit 13 calculates a difference d1 between the average value A1 and the filter coefficient h1 corresponding to the latest update timing for each tap tp1 in the variable filter unit 31. That is, the detection unit 13 calculates L differences d1 corresponding to the L taps tp1, respectively. The detection unit 13 performs detection processing based on each calculated difference d1.

[0082] For example, the detection unit 13 can perform both a detection process based on the amount of change over time in the increasing direction of the filter coefficient h1 and a detection process based on the amount of change over time in the decreasing direction of the filter coefficient h1.

[0083] More specifically, the storage unit 12 stores an abnormality determination condition C1 that is determined using a threshold value for the amount of change over time in the increasing direction of the filter coefficient h1 and a threshold value for the amount of change over time in the decreasing direction of the filter coefficient h1. The abnormality determination condition C1 is an index for determining whether the difference d1 is an abnormal value.

[0084] Each time the detection unit 13 calculates L differences d1, it counts the number of differences d1 that satisfy the abnormality determination condition C1 among the calculated L differences d1. If the number of differences d1 that satisfy the abnormality determination condition C1 is equal to or greater than a predetermined value, the detection unit 13 determines that the filter coefficient h1 is an abnormal value. On the other hand, if the number of differences d1 that satisfy the abnormality determination condition C1 is less than the predetermined value, the detection unit 13 determines that the filter coefficient h1 is a normal value.

[0085] That is, when the detection unit 13 determines that the filter coefficient h1 is an abnormal value, it determines that an abnormality has occurred in the transmission line 1.

[0086] (Detection process using equalizer filter coefficient h2) (Detection example 3) When the acquisition unit 11 stores M filter coefficients h2 in the storage unit 12 at a timing according to the cycle T1, the detection unit 13 calculates an average value E2 of the M filter coefficients h2.

[0087] For example, the storage unit 12 stores an upper threshold EU2 and a lower threshold EL2 for the average value E2. The upper threshold EU2 and the lower threshold EL2 are set in advance based on the distribution of the average value E2, for example.

[0088] Each time the detection unit 13 calculates the average value E2, it compares the calculated average value E2 with an upper threshold value EU2 and a lower threshold value EL2. If the calculated average value E2 is equal to or greater than the lower threshold value EL2 and equal to or less than the upper threshold value EU2, the detection unit 13 determines that no abnormality has occurred in the transmission line 1. On the other hand, if the calculated average value E2 is less than the lower threshold value EL2 or greater than the upper threshold value EU2, the detection unit 13 determines that an abnormality has occurred in the transmission line 1.

[0089] (Detection example 4) The detection unit 13 performs the detection process based on the amount of change over time of the filter coefficient h2. For example, the detection unit 13 performs the detection process by comprehensively determining the amount of change over time of M filter coefficients h2 corresponding to M taps tp2 in the variable filter unit 41 of the equalizer 40.

[0090] More specifically, when the acquisition unit 11 updates the time series data Dt2 at a timing according to the period T1, the detection unit 13 calculates, for each tap tp2 in the variable filter unit 41, an average value A2 of multiple filter coefficients h2 corresponding to the most recent multiple update timings. That is, the detection unit 13 calculates M average values ​​A2 corresponding to the M taps tp2, respectively.

[0091] Then, the detection unit 13 calculates a difference d2 between the average value A2 and the filter coefficient h2 corresponding to the latest update timing for each tap tp2 in the variable filter unit 41. That is, the detection unit 13 calculates M differences d2 corresponding to the M taps tp2, respectively. The detection unit 13 performs detection processing based on each calculated difference d2.

[0092] For example, the detection unit 13 can perform both a detection process based on the amount of change over time in the increasing direction of the filter coefficient h2 and a detection process based on the amount of change over time in the decreasing direction of the filter coefficient h2.

[0093] More specifically, the storage unit 12 stores an abnormality determination condition C2 that is determined using a threshold value for the amount of change over time in the increasing direction of the filter coefficient h2 and a threshold value for the amount of change over time in the decreasing direction of the filter coefficient h2. The abnormality determination condition C2 is an index for determining whether the difference d2 is an abnormal value.

[0094] Each time the detection unit 13 calculates M differences d2, it counts the number of differences d2 that satisfy the abnormality determination condition C2 among the M calculated differences d2. If the number of differences d2 that satisfy the abnormality determination condition C2 is equal to or greater than a predetermined value, the detection unit 13 determines that the filter coefficient h2 is an abnormal value. On the other hand, if the number of differences d2 that satisfy the abnormality determination condition C2 is less than the predetermined value, the detection unit 13 determines that the filter coefficient h2 is a normal value.

[0095] That is, when the detection unit 13 determines that the filter coefficient h2 is an abnormal value, it determines that an abnormality has occurred in the transmission line 1.

[0096] (Detection process using the echo canceller filter coefficient h3) (Detection example 5) When the acquisition unit 11 stores N filter coefficients h3 in the storage unit 12 at a timing according to the cycle T1, the detection unit 13 calculates an average value E3 of the N filter coefficients h3.

[0097] For example, the storage unit 12 stores an upper threshold EU3 and a lower threshold EL3 for the average value E3. The upper threshold EU3 and the lower threshold EL3 are set in advance based on the distribution of the average value E3, for example.

[0098] Each time the detection unit 13 calculates the average value E3, it compares the calculated average value E3 with an upper threshold value EU3 and a lower threshold value EL3. If the calculated average value E3 is equal to or greater than the lower threshold value EL3 and equal to or less than the upper threshold value EU3, the detection unit 13 determines that no abnormality has occurred in the transmission line 1. On the other hand, if the calculated average value E3 is less than the lower threshold value EL3 or greater than the upper threshold value EU3, the detection unit 13 determines that an abnormality has occurred in the transmission line 1.

[0099] (Detection example 6) The detection unit 13 performs detection processing based on the amount of change over time of the filter coefficient h3. For example, the detection unit 13 performs detection processing by comprehensively determining the amount of change over time of N filter coefficients h3 corresponding to N taps tp3 in the variable filter unit 51 of the echo canceller 50.

[0100] More specifically, when the acquisition unit 11 updates the time series data Dt3 at a timing according to the period T1, the detection unit 13 calculates an average value A3 of multiple filter coefficients h3 corresponding to the most recent multiple update timings for each tap tp3 in the variable filter unit 51. That is, the detection unit 13 calculates N average values ​​A3 corresponding to the N taps tp3, respectively.

[0101] The detection unit 13 includes a variable filter unit 51 For each tap tp3 in the table, the detection unit 13 calculates a difference d3 between the average value A3 and the filter coefficient h3 corresponding to the latest update timing. That is, the detection unit 13 calculates N differences d3 corresponding to the N taps tp3, respectively. The detection unit 13 performs detection processing based on the calculated differences d3.

[0102] For example, the detection unit 13 can perform both a detection process based on the amount of change over time in the increasing direction of the filter coefficient h3 and a detection process based on the amount of change over time in the decreasing direction of the filter coefficient h3.

[0103] More specifically, the storage unit 12 stores an abnormality determination condition C3 that is determined using a threshold value for the amount of change over time in the increasing direction of the filter coefficient h3 and a threshold value for the amount of change over time in the decreasing direction of the filter coefficient h3. The abnormality determination condition C3 is an index for determining whether the difference d3 is an abnormal value.

[0104] Each time the detection unit 13 calculates N differences d3, it counts the number of differences d3 that satisfy the abnormality determination condition C3 among the N calculated differences d3. If the number of differences d3 that satisfy the abnormality determination condition C3 is equal to or greater than a predetermined value, the detection unit 13 determines that the filter coefficient h3 is an abnormal value. On the other hand, if the number of differences d3 that satisfy the abnormality determination condition C3 is less than the predetermined value, the detection unit 13 determines that the filter coefficient h3 is a normal value.

[0105] That is, when the detection unit 13 determines that the filter coefficient h3 is an abnormal value, it determines that an abnormality has occurred in the transmission line 1.

[0106] (Detection process using filter coefficients h1, h2, h3) (Detection example 7) The detection unit 13 performs the detection process based on the amount of change over time of the filter coefficients h1, h2, and h3 acquired by the acquisition unit 11. More specifically, the detection unit 13 performs the detection process by comprehensively determining the amount of change over time of the filter coefficients h1, h2, and h3 acquired by the acquisition unit 11.

[0107] FIG. 11 is a diagram illustrating the time constants of the variable filter units and the detection sensitivities for various abnormalities in the detection device according to the embodiment of the present disclosure.

[0108] 11, for example, the time constants of the baseline wander correction unit 30, the equalizer 40, and the echo canceller 50 are different from one another. Specifically, of the time constant τ1 of the variable filter unit 31 in the baseline wander correction unit 30, the time constant τ2 of the variable filter unit 41 in the equalizer 40, and the time constant τ3 of the variable filter unit 51 in the echo canceller 50, the time constant τ1 is the longest, the time constant τ2 is the next longest, and the time constant τ3 is the shortest.

[0109] Furthermore, the detection sensitivity for signs of disconnection of the transmission line 1 is highest in the detection process using the filter coefficient h1, next highest in the detection process using the filter coefficient h2, and lowest in the detection process using the filter coefficient h3.

[0110] Furthermore, the detection sensitivity for detecting a break in the transmission line 1 is highest in the detection process using the filter coefficient h3, and next highest in the detection process using the filter coefficients h1 and h2.

[0111] In addition, the detection sensitivity to the connection of other devices to the transmission line 1, i.e., tapping, is highest for the detection process using the filter coefficient h2, next highest for the detection process using the filter coefficient h3, and lowest for the detection process using the filter coefficient h1.

[0112] The detection unit 13 utilizes the detection sensitivity characteristics of the detection process using the filter coefficients h1, h2, and h3 to determine whether or not an abnormality has occurred in the transmission line 1, and also determines the type of abnormality that has occurred, based on the determination results of whether or not the filter coefficients h1, h2, and h3 in the above-mentioned detection examples 2, 4, and 6 are abnormal values.

[0113] FIG. 12 is a diagram illustrating a correspondence relationship between a determination result regarding a filter coefficient in a detection process of a detection device according to an embodiment of the present disclosure and a result of the detection process.

[0114] 12, for example, when the detection unit 13 determines that the filter coefficients h1, h2, and h3 are abnormal values, it determines that a break has occurred in the transmission line 1.

[0115] Furthermore, for example, when the detection unit 13 determines that the filter coefficients h1 and h2 are abnormal values ​​and the filter coefficient h3 is a normal value, it determines that there is a sign of a break in the transmission line 1.

[0116] Furthermore, for example, when the detection unit 13 determines that the filter coefficients h2 and h3 are abnormal values ​​and the filter coefficient h1 is normal, it determines that tapping has occurred in the transmission line 1.

[0117] Furthermore, for example, even if the detection unit 13 determines that the filter coefficient h2 is an abnormal value, if the detection unit 13 determines that the filter coefficients h1 and h3 are normal values, the detection unit 13 determines that no abnormality has occurred in the transmission line 1. In other words, if the detection unit 13 determines that at least two of the filter coefficients h1, h2, and h3 acquired by the acquisition unit 11 are abnormal values, the detection unit 13 determines that an abnormality has occurred in the transmission line 1.

[0118] The detection unit 13 may be configured not to perform the detection processing for some of the detection examples 1 to 7.

[0119] When the detection unit 13 determines that an abnormality has occurred in the transmission line 1, it notifies the result of the detection process to another detection device 101 or a device external to the communication system 301 via a transmission line (not shown). Note that when the detection unit 13 determines that an abnormality has occurred in the transmission line 1, it may be configured to cut off the connection between the signal transmission device 201 and another signal transmission device 201 via the transmission line 1, for example, by controlling to turn off a switch provided on the transmission line 1.

[0120] [Operation flow] Each device in a communication system according to an embodiment of the present disclosure includes a computer including a memory, and a processing unit such as a CPU in the computer reads from the memory and executes a program including some or all of the steps in the following flowcharts and sequences. The programs for each of these devices can be installed externally. The programs for each of these devices are distributed in a state stored on a recording medium or via a communication line.

[0121] 13 is a flowchart defining an example of an operation procedure when a detection device according to an embodiment of the present disclosure performs a detection process. FIG. 13 shows a flowchart of the detection process of Detection Example 7. In the following, it is assumed that the number of taps tp1 of the variable filter unit 31, the number of taps tp2 of the variable filter unit 41, and the number of taps tp3 of the variable filter unit 51 are three. Note that the number of taps tp1 of the variable filter unit 31, the number of taps tp2 of the variable filter unit 41, and the number of taps tp3 of the variable filter unit 51 may be two, four, or more.

[0122] 13, first, the detection device 101 monitors the filter calculation unit 32 in the baseline wander correction unit 30, the filter calculation unit 42 in the equalizer 40, and the filter calculation unit 52 in the echo canceller 50, and waits for updates of the filter coefficients h1, h2, and h3 of the taps tp1, tp2, and tp3 in the variable filter units 31, 41, and 51, respectively (NO in step S102).When the filter coefficients h1, h2, and h3 are updated (YES in step S102), the detection device 101 acquires the updated filter coefficients h1, h2, and h3.The detection device 101 updates the time-series data Dt1, Dt2, and Dt3 by adding the acquired filter coefficients h1, h2, and h3 to the time-series data Dt1, Dt2, and Dt3 in the storage unit 12 (step S104).

[0123] Next, the detection device 101 calculates average values ​​A1, A2, and A3. More specifically, the detection device 101 calculates the average value A1 of a plurality of filter coefficients h1 corresponding to the most recent update timings in the time-series data Dt1 for each tap tp1, thereby calculating the three average values ​​A1 for each tap tp1. Furthermore, the detection device 101 calculates the average value A2 of a plurality of filter coefficients h2 corresponding to the most recent update timings in the time-series data Dt2 for each tap tp2, thereby calculating the three average values ​​A2 for each tap tp2. Furthermore, the detection device 101 calculates the average value A3 of a plurality of filter coefficients h3 corresponding to the most recent update timings in the time-series data Dt3 for each tap tp3, thereby calculating the three average values ​​A3 for each tap tp3 (step S106).

[0124] Next, the detection device 101 calculates differences d1, d2, and d3. More specifically, the detection device 101 calculates the difference d1 between the average value A1 and the latest filter coefficient h1 for each tap tp1, thereby calculating three differences d1 for each tap tp1. The detection device 101 also calculates the difference d2 between the average value A2 and the latest filter coefficient h2 for each tap tp2, thereby calculating three differences d2 for each tap tp2. The detection device 101 also calculates the difference d3 between the average value A3 and the latest filter coefficient h3 for each tap tp3, thereby calculating three differences d3 for each tap tp3 (step S108).

[0125] Next, the detection device 101 determines whether the acquired filter coefficients h1, h2, and h3 are abnormal values ​​based on the abnormality determination conditions C1, C2, and C3. More specifically, the detection device 101 determines whether the filter coefficient h1 is an abnormal value based on the number of the three calculated differences d1 that satisfy the abnormality determination condition C1. The detection device 101 also determines whether the filter coefficient h2 is an abnormal value based on the number of the three calculated differences d2 that satisfy the abnormality determination condition C2. The detection device 101 also determines whether the filter coefficient h3 is an abnormal value based on the number of the three calculated differences d3 that satisfy the abnormality determination condition C3 (step S110).

[0126] Next, the detection device 101 performs a detection process by comprehensively determining the amount of change over time in the filter coefficients h1, h2, and h3. More specifically, the detection device 101 determines whether an abnormality has occurred in the transmission line 1 and determines the type of abnormality based on the determination result of whether the filter coefficients h1, h2, and h3 are abnormal values ​​(step S112).

[0127] Next, if the detection device 101 determines that no abnormality has occurred in the transmission line 1 (NO in step S114), it waits for the next update of the filter coefficients h1, h2, and h3 (NO in step S102).

[0128] On the other hand, if the detecting device 101 determines that an abnormality has occurred in the transmission line 1 (YES in step S114), it notifies the result of the detection process to another detecting device 101 or a device external to the communication system 301 (step S116).

[0129] Next, the detection device 101 waits for the next update of the filter coefficients h1, h2, and h3 (NO in step S102).

[0130] In the communication systems 301 and 302 according to the embodiments of the present disclosure, the signal transmission device 201 is configured to include the baseline wander correction unit 30, the equalizer 40, and the echo canceller 50, but this is not limiting. The signal transmission device 201 may be configured to include other adaptive filters instead of some or all of the baseline wander correction unit 30, the equalizer 40, and the echo canceller 50, or may be configured to include other adaptive filters in addition to the baseline wander correction unit 30, the equalizer 40, and the echo canceller 50. For example, the signal transmission device 201 includes a crosstalk canceller as the other adaptive filter for removing electromagnetic wave induced signals from digital signals output from other adjacent communication systems 301 and 302. In this case, the acquisition unit 11 in the detection device 101 may be configured to acquire the filter coefficients of the crosstalk canceller.

[0131] Furthermore, although the signal transmission device 201 according to the embodiment of the present disclosure has been described as including the transceiver unit 21, the present disclosure is not limited to this. The signal transmission device 201 may be configured to include a receiver instead of the transceiver unit 21. That is, the signal transmission device 201 may be configured to receive analog signals from other signal transmission devices 201 via the transmission line 1, but not to transmit analog signals to other signal transmission devices 201.

[0132] In addition, in the signal transmission device 201 according to the embodiment of the present disclosure, the time constant τ1 of the variable filter unit 31 in the baseline wander correction unit 30, the time constant τ2 of the variable filter unit 41 in the equalizer 40, and the time constant τ3 of the variable filter unit 51 in the echo canceller 50 are configured to be different from one another, but this is not limitative. Some or all of the time constants τ1, τ2, and τ3 may have the same value.

[0133] Furthermore, in the detection device 101 according to the embodiment of the present disclosure, the acquisition unit 11 is configured to acquire the filter coefficients h1, h2, and h3, respectively, but this is not limiting. The acquisition unit 11 may be configured to acquire one or two of the filter coefficients h1, h2, and h3. In this case, the detection unit 13 performs detection processing based on the amount of change over time of the filter coefficients acquired by the acquisition unit 11.

[0134] Furthermore, in the detection device 101 according to the embodiment of the present disclosure, the acquisition unit 11 is configured to acquire the filter coefficient h1 of each of the L taps tp1 in the variable filter unit 31 of the baseline wander correction unit 30, but this is not limited to this. The acquisition unit 11 may be configured to acquire the filter coefficient h1 of some of the L taps tp1. For example, the acquisition unit 11 acquires the filter coefficient h1 of any one of the L taps tp1. In this case, the detection unit 13 performs detection processing based on the amount of change over time in the filter coefficient h1 of the tap tp1.

[0135] Similarly, the acquisition unit 11 may be configured to acquire the filter coefficient h2 of some of the M taps tp2. For example, the acquisition unit 11 acquires the filter coefficient h2 of any one of the M taps tp2. In this case, the detection unit 13 performs the detection process based on the amount of change over time in the filter coefficient h2 of the tap tp2. The acquisition unit 11 may also be configured to acquire the filter coefficient h3 of some of the N taps tp3. For example, the acquisition unit 11 acquires the filter coefficient h3 of any one of the N taps tp3. In this case, the detection unit 13 performs the detection process based on the amount of change over time in the filter coefficient h3 of the tap tp3.

[0136] Furthermore, for example, the acquisition unit 11 acquires a filter coefficient h1 of any one of the L taps tp1, a filter coefficient h2 of any one of the M taps tp2, and a filter coefficient h3 of any one of the N taps tp3. In this case, the detection unit 13 performs detection processing by comprehensively determining the amount of change over time in the filter coefficient h1 of the tap tp1, the amount of change over time in the filter coefficient h2 of the tap tp2, and the amount of change over time in the filter coefficient h3 of the tap tp3.

[0137] Furthermore, in the detection device 101 according to the embodiment of the present disclosure, the detection unit 13 is configured to perform the detection process using the abnormality determination condition C1 that is determined using a threshold value for the amount of change over time in the increasing direction of the filter coefficient h1 and a threshold value for the amount of change over time in the decreasing direction of the filter coefficient h1, but this is not limited to this. The detection unit 13 may also be configured to perform statistical analysis of the calculated differences d1 and perform the detection process based on the analysis results, without using the abnormality determination condition C1.

[0138] Similarly, the detection unit 13 may be configured to perform statistical analysis of each calculated difference d2 and perform detection processing based on the analysis result without using the abnormality determination condition C2. Furthermore, the detection unit 13 may be configured to perform statistical analysis of each calculated difference d3 and perform detection processing based on the analysis result without using the abnormality determination condition C3.

[0139] However, there is a demand for a technology that can more accurately detect abnormalities in transmission lines. The technology described in Patent Document 1 detects the frequency of short interruptions in a transmission line based on the frequency at which the filter coefficient determined by the echo canceller becomes a constant value, and the method described in Patent Document 1 may not be able to accurately detect abnormalities in the transmission line. There is a need for a technology that goes beyond the technology described in Patent Document 1 and that is capable of detecting abnormalities in transmission lines more accurately.

[0140] In contrast, the detection device 101 of the present disclosure is a detection device provided in correspondence with a signal transmission device 201 having an adaptive filter that receives a received signal via a transmission line 1 and applies the adaptive filter to the received signal. An acquisition unit 11 acquires a filter coefficient of the adaptive filter. A detection unit 13 detects an abnormality in the transmission line 1 based on the amount of change over time in the filter coefficient acquired by the acquisition unit 11.

[0141] With this configuration, an abnormality in the transmission line 1 can be detected based on the amount of change over time (the trend of change) of the filter coefficient, so that, compared to a configuration that simply uses the change over time of the filter coefficient, even if the change in the filter coefficient is small, an abnormality in the transmission line 1 can be detected early and accurately. Therefore, an abnormality in the transmission line 1 can be detected more accurately.

[0142] 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.

[0143] The above description includes the following additional features. [Appendix 1] A detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies the adaptive filter to the received signal, an acquisition unit that acquires a filter coefficient of the adaptive filter; a detection unit that detects an abnormality in the transmission line based on the amount of change over time of the filter coefficient acquired by the acquisition unit, the acquisition unit acquires the filter coefficients of the plurality of adaptive filters corresponding to one of the transmission lines, the detection unit detects an abnormality in the transmission line based on the amount of change over time of each of the filter coefficients acquired by the acquisition unit; The detection unit determines whether an abnormality has occurred in the transmission line and determines the type of abnormality that has occurred. [Explanation of symbols]

[0144] 1 Transmission Line 1A cable section 1B Connector part 11 Acquisition Department 12 Storage section 13 Detection unit 21 Transmitter / receiver 22 ADC 23 DAC 24 Processing section 30 Baseline wander correction section 31, 41, 51 Variable filter section 32, 42, 52 Filter calculation section 33,53 subtractor 40 Equalizer 50 Echo Canceller 101 Detection device 201 Signal transmission device 301,302 Communication Systems R1,R2 terminating resistor tp1,tp2,tp3 taps

Claims

1. A detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies the adaptive filter to the received signal, an acquisition unit that acquires filter coefficients of the plurality of adaptive filters corresponding to one of the transmission lines; a detection unit that detects an abnormality in the transmission line based on the amount of change over time of each of the filter coefficients acquired by the acquisition unit.

2. The detection device of claim 1 , wherein the plurality of adaptive filters have different time constants.

3. the acquisition unit acquires the filter coefficients of a plurality of taps in the adaptive filter, each of the taps corresponding to one of the transmission lines; The detection device according to claim 1 , wherein the detection unit detects an abnormality in the transmission line based on the amount of change over time of each of the filter coefficients acquired by the acquisition unit.

4. 4. The detection device according to claim 1, wherein the detection unit detects an abnormality in the transmission line based on an amount of change over time in an increasing direction of the filter coefficient, and detects an abnormality in the transmission line based on an amount of change over time in a decreasing direction of the filter coefficient.

5. The detection device according to claim 1 , wherein the acquisition unit acquires, as the filter coefficients of the adaptive filter, filter coefficients of at least one of a baseline wander correction unit, an equalizer, and an echo canceller.

6. 3. The detection device according to claim 1, wherein the acquisition unit acquires three filter coefficients of a baseline wander correction unit, an equalizer, and an echo canceller as the filter coefficients of the plurality of adaptive filters.

7. 7. The detection device according to claim 6, wherein the detection unit determines that an abnormality exists in the transmission line when it determines that at least two of the three filter coefficients acquired by the acquisition unit are abnormal values.

8. the detection unit determines that the transmission line is abnormal when the number of differences that satisfy an abnormality determination condition is equal to or greater than a predetermined value, and determines that the transmission line is normal when the number of differences that satisfy the abnormality determination condition is less than the predetermined value; The detection device according to claim 1 , wherein the abnormality determination condition is determined using a threshold value of the amount of change over time.

9. A detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies the adaptive filter to the received signal, an acquisition unit that acquires a filter coefficient of the adaptive filter; a detection unit that detects an abnormality in the transmission line based on the amount of change over time of the filter coefficient acquired by the acquisition unit, The detection device, wherein the acquisition unit acquires, as the filter coefficients of the adaptive filter, filter coefficients of at least one of a baseline wander correction unit and an equalizer.

10. 1. A detection method in a detection device provided corresponding to a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies the adaptive filter to the received signal, comprising: obtaining filter coefficients of the plurality of adaptive filters corresponding to one of the transmission lines; and detecting an abnormality in the transmission line based on the acquired amount of change over time of each of the filter coefficients.

11. A detection program used in a detection device provided in correspondence with a signal transmission device having an adaptive filter that receives a received signal via a transmission line and applies the adaptive filter to the received signal, Computer, an acquisition unit that acquires filter coefficients of the plurality of adaptive filters corresponding to one of the transmission lines; a detection unit that detects an abnormality in the transmission line based on the amount of change over time of each of the filter coefficients acquired by the acquisition unit; A detection program to function as a

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