Processing system, first processing device, second processing device, program, and detection method

Abstract

This processing system comprises: a first processing device that transmits a transmission signal; and a second processing device that receives the transmission signal transmitted via a wired transmission path. The output impedance of the first processing device and / or the input impedance of the second processing device is different from the characteristic impedance of the transmission path. The second processing device has a detection unit that detects the state of the transmission path on the basis of a reception signal, which is the transmission signal received by the second processing device.

Description

Processing system, first processing device, second processing device, program, and detection method

[0001] The present disclosure relates to a technique for detecting the state of a transmission line.

[0002] Patent Document 1 discloses a technique for detecting the position of a defective portion of a transmission cable.

[0003] Japanese Patent Application Laid-Open No. 2016-201589

[0004] There is room for improvement in the technique for detecting the state of a transmission line.

[0005] An object of the present disclosure is to provide a technique capable of easily detecting the state of a transmission line.

[0006] One aspect of a processing system includes a first processing device that transmits a transmission signal and a second processing device that receives the transmission signal transmitted through a wired transmission line. At least one of the output impedance of the first processing device and the input impedance of the second processing device is different from the characteristic impedance of the transmission line. The second processing device has a detection unit that detects the state of the transmission line based on a reception signal that is the transmission signal received by the second processing device.

[0007] One aspect of the second processing device is the second processing device included in the above processing system.

[0008] One aspect of the first processing device is the first processing device included in the above processing system.

[0009] One aspect of a program is a program for causing a computer device to function as the above second processing device.

[0010] One aspect of a program is a program for causing a computer device to function as the above first processing device.

[0011] One aspect of the detection method involves a first processing unit transmitting a transmission signal, a second processing unit receiving the transmission signal transmitted through a wired transmission line, and at least one of the output impedance of the first processing unit and the input impedance of the second processing unit being different from the characteristic impedance of the transmission line. The second processing unit then detects the state of the transmission line based on the received signal, which is the transmission signal received by the second processing unit.

[0012] The state of the transmission line can be easily detected.

[0013] Figure 1 is a schematic diagram showing an example of a processing system. Figure 2 is a flowchart showing an example of the operation of the processing system. Figure 3 is a schematic diagram showing a transmission system. Figure 4 is a graph showing an example of the frequency characteristics of the transmission signal's pass characteristics in the transmission line. Figure 5 is a graph showing an example of the frequency characteristics of the transmission signal's pass characteristics in the transmission line. Figure 6 is a schematic diagram showing a transmission system. Figure 7 is a graph showing an example of the frequency characteristics of the transmission signal's pass characteristics in the transmission line. Figure 8 is a schematic diagram showing a transmission system. Figure 9 is a graph showing an example of the frequency characteristics of the transmission signal's pass characteristics in the transmission line. Figure 10 is a schematic diagram showing a transmission system. Figure 11 is a graph showing an example of the frequency characteristics of the transmission signal's pass characteristics in the transmission line. Figure 12 is a graph showing an example of the frequency characteristics of the transmission signal's pass characteristics in the transmission line. Figure 13 is a graph showing an example of the frequency characteristics of the transmission signal's pass characteristics in the transmission line. Figure 14 is a flowchart showing an example of the operation of the processing system. Figure 15 is a schematic diagram showing an example of the frequency spectra of the input and output signals of an AD converter. Figure 16 is a schematic diagram showing an example of the frequency spectra of the input and output signals of an AD converter. Figure 17 is a schematic diagram showing an example of the frequency spectra of the input and output signals of an AD converter. Figure 18 is a graph showing an example of the frequency characteristics of the signal intensity of the input signal of an AD converter acquired based on the output signal of an AD converter. Figure 19 is a graph showing an example of the frequency characteristics of the signal intensity of the input signal of an AD converter acquired based on the output signal of an AD converter. Figure 20 is a schematic diagram showing an example of a processing system. Figure 21 is a flowchart showing an example of the operation of the second processing unit. Figure 22 is a flowchart showing an example of the operation of the processing system. Figure 23 is a graph showing an example of the virtual detection time characteristics. Figure 24 is a graph showing an example of the frequency characteristics of the transmission signal's pass-through characteristics in the transmission line. Figure 25 is a graph showing an example of the frequency characteristics of the transmission signal's pass-through characteristics in the transmission line. Figure 26 is a schematic diagram illustrating a transmission system. Figure 27 is a schematic diagram illustrating a transmission system. Figure 28 is a graph showing an example of the frequency characteristics of the transmission signal's pass-through characteristics in the transmission line.

[0014] <Overview of the Processing System> Figure 1 is a schematic diagram showing an example of the processing system 3. As shown in Figure 1, the processing system 3 comprises a first processing unit 1 and a second processing unit 2. The first processing unit 1 and the second processing unit 2 are connected to each other by a wired transmission line 5. The transmission line 5 is, for example, a cable. The transmission line 5 may be a stranded cable composed of multiple strands, or it may be a single-wire cable. In this example, the processing system 3 and the transmission line 5 constitute the transmission system 4.

[0015] The processing system 3 can, for example, detect the state of the transmission line 5. The first processing unit 1 transmits a transmission signal to the transmission line 5. The second processing unit 2 receives the transmission signal transmitted through the transmission line 5. The second processing unit 2 can detect the state of the transmission line 5 based on the received signal, which is the transmission signal received from the first processing unit 1 through the transmission line 5.

[0016] The second processing unit 2 can, for example, detect signs of a break in the transmission line 5 (in other words, the cable). It can also be said that the second processing unit 2 can detect signs of a break in the transmission line 5. Furthermore, it can be said that the second processing unit 2 can detect that a break is likely to occur in the transmission line 5. If the transmission line 5 is a stranded cable, it can be said that there are signs of a break in the transmission line 5 when some of the strands among the multiple strands that make up the stranded cable are broken. It can also be said that the second processing unit 2 can detect that some of the multiple strands that make up the stranded cable as the transmission line 5 are broken.

[0017] Furthermore, in the processing system 3, the first processing unit 1 and the second processing unit 2 can communicate data through the transmission line 5. The processing system 3 includes, for example, a detection mode for detecting the state of the transmission line 5 and a data communication mode for performing data communication. In the detection mode, the first processing unit 1 transmits a transmission signal, and the second processing unit 2 detects the state of the transmission line 5 based on a received signal corresponding to the transmission signal. In the data communication mode, the first processing unit 1 and the second processing unit 2 communicate data through the transmission line 5.

[0018] The processing system 3 operates in data communication mode, for example, in its initial state. The processing system 3 basically operates in data communication mode. When predetermined conditions are met, the processing system 3 temporarily switches its operating mode from data communication mode to detection mode and executes a detection process to detect the state of the transmission line 5. When the detection process is completed, the processing system 3 returns its operating mode from detection mode to data communication mode. Hereafter, the predetermined conditions for the processing system 3 to transition from data communication mode to detection mode will be called the detection execution conditions. The detection execution conditions can also be said to be the conditions for the processing system 3 to start executing the detection process.

[0019] The detection execution condition may also be the passage of a certain period of time. In this case, the processing system 3 switches its operating mode from data communication mode to detection mode at regular intervals and performs detection processing. This regular period may be one day, several days, or one month. Alternatively, the detection execution condition may also be that the processing system 3 receives an instruction to execute detection processing (also called a detection execution instruction) from an external device (also called an external device). In this case, when the processing system 3 receives a detection execution instruction from an external device, it switches its operating mode from data communication mode to detection mode and performs detection processing.

[0020] <Example of the configuration of the first processing unit> The first processing unit 1 includes, for example, a processing unit 10, a storage unit 11, a DA converter 15, an AD converter 16, and a variable termination resistor 18. The first processing unit 1 is, for example, a computer device. The first processing unit 1 can also be called, for example, a processing circuit.

[0021] The processing unit 10 includes, for example, at least one processor. The at least one processor in the processing unit 10 may include, for example, a CPU (Central Processing Unit). The processing unit 10 can also be called, for example, a processing circuit.

[0022] The memory unit 11 may include, for example, non-temporary recording media that can be read by the CPU of the processing unit 10, such as ROM (Read Only Memory) and RAM (Random Access Memory). The memory unit 11 can also be called, for example, a memory circuit. The memory unit 11 stores, for example, a program 11a for controlling the first processing unit 1. Various functions of the processing unit 10 are realized, for example, by the CPU of the processing unit 10 executing the program 11a in the memory unit 11.

[0023] The processing unit 10 generates a transmission signal to be transmitted to the second processing unit 2. The processing unit 10 generates a transmission signal in digital format. The DA converter 15 converts the transmission signal generated by the processing unit 10 from digital format to analog format and outputs the analog transmission signal to the transmission line 5. The transmission line 5 transmits the analog transmission signal from the DA converter 15 to the second processing unit 2.

[0024] The transmission line 5 transmits the analog transmission signal sent by the second processing unit 2 to the first processing unit 1. The AD converter 16 of the first processing unit 1 converts the transmission signal from the second processing unit 2 transmitted through the transmission line 5 from analog to digital, and outputs the digital transmission signal to the processing unit 10. The processing unit 10 performs processing using the digital transmission signal.

[0025] Hereafter, the transmission signal transmitted by the first processing unit 1 may be referred to as the first transmission signal, and the transmission signal transmitted by the second processing unit 2 may be referred to as the second transmission signal.

[0026] One end of the variable termination resistor 18 is connected to the output of the DA converter 15 and the input of the AD converter 16. The other end of the variable termination resistor 18 is connected to the ground or virtual ground of the first processing unit 1. The processing unit 10 can change the resistance value of the variable termination resistor 18.

[0027] The resistance value of the variable termination resistor 18 constitutes the output impedance when the first processing unit 1 transmits the first transmission signal. The output impedance can also be called the transmission impedance. Furthermore, the resistance value of the variable termination resistor 18 constitutes the input impedance when the first processing unit 1 receives the second transmission signal. The input impedance can also be called the reception impedance.

[0028] The configuration of the first processing unit 1 is not limited to the example described above. For example, at least one processor in the processing unit 10 may include multiple CPUs, or at least one DSP (Digital Signal Processor). Furthermore, all or some of the functions of the processing unit 10 may be implemented by hardware circuits that do not require software to realize those functions. In addition, the storage unit 11 may include a small hard disk drive and an SSD (Solid State Drive), etc.

[0029] <Example of the configuration of the second processing unit> The second processing unit 2 has a configuration similar to that of the first processing unit 1, for example. The second processing unit 2 includes, for example, a processing unit 20, a storage unit 21, a DA converter 25, an AD converter 26, and a variable termination resistor 28. The second processing unit 2 is, for example, a computer device. The second processing unit 2 can also be called, for example, a processing circuit.

[0030] The processing unit 20 includes, for example, at least one processor. The at least one processor included in the processing unit 20 may include, for example, a CPU. The processing unit 20 can also be called, for example, a processing circuit.

[0031] The memory unit 21 may include, for example, a non-temporary recording medium that can be read by the CPU of the processing unit 20, such as ROM and RAM. The memory unit 21 can also be called, for example, a memory circuit. The memory unit 21 stores, for example, a program 21a for controlling the second processing unit 2. Various functions of the processing unit 20 are realized, for example, by the CPU of the processing unit 20 executing the program 21a in the memory unit 21.

[0032] The processing unit 20 generates a second transmission signal in digital format. The DA converter 25 converts the second transmission signal generated by the processing unit 20 from digital format to analog format and outputs the second transmission signal in analog format to the transmission line 5. The transmission line 5 transmits the second transmission signal in analog format to the first processing unit 1.

[0033] The AD converter 26 converts the first transmission signal from the first processing unit 1 transmitted through the transmission line 5 from analog format to digital format, and outputs the digital first transmission signal to the processing unit 20. The processing unit 20 performs processing using the digital first transmission signal.

[0034] One end of the variable termination resistor 28 is connected to the output of the DA converter 25 and the input of the AD converter 26. The other end of the variable termination resistor 28 is connected to the ground or virtual ground of the second processing unit 2. The processing unit 20 can change the resistance value of the variable termination resistor 28.

[0035] The resistance value of the variable termination resistor 28 constitutes the output impedance when the second processing unit 2 transmits the second transmission signal. Furthermore, the resistance value of the variable termination resistor 28 constitutes the input impedance when the second processing unit 2 receives the first transmission signal.

[0036] In the second processing unit 2, for example, the AD converter 26 and the processing unit 20 function as a detection unit 29 that detects the state of the transmission line 5 based on the received signal, which is the first transmitted signal, received by the second processing unit 2 through the transmission line 5.

[0037] The configuration of the second processing unit 2 is not limited to the example described above. For example, at least one processor in the processing unit 20 may include multiple CPUs or at least one DSP. Furthermore, all or some of the functions of the processing unit 20 may be implemented by hardware circuits that do not require software to realize those functions. In addition, the storage unit 21 may include a small hard disk drive and an SSD.

[0038] <Example of operation of the processing system in data communication mode> In data communication mode, the first processing unit 1 and the second processing unit 2 can, for example, perform bidirectional data communication. In data communication mode, the state of the transmission line 5 is not detected. The first processing unit 1 and the second processing unit 2 can each be described as, for example, a communication device or a transceiver.

[0039] In data communication mode, the processing unit 10 of the first processing unit 1 generates a first transmission signal containing data. For example, the processing unit 10 generates a modulated signal digitally modulated based on the data as the first transmission signal containing data. Hereafter, the modulated signal as the first transmission signal will be referred to as the first modulated signal. The first modulated signal generated by the processing unit 10 can also be said to be, for example, a digital baseband signal. The first modulated signal is a signal containing data.

[0040] The modulation scheme of the first modulated signal may be, for example, ASK (Amplitude Shift Keying), PSK (Phase Shift Keying), NRZ (Non Return to Zero), OFDM (Orthogonal Frequency-Division Multiplexing), or any other scheme. The DA converter 15 converts the first modulated signal from digital format to analog format and outputs the analog format first modulated signal to the transmission line 5.

[0041] In the second processing unit 2, which receives the first modulated signal from the transmission line 5, the AD converter 26 converts the first modulated signal from analog format to digital format and outputs the digital first modulated signal to the processing unit 20. The processing unit 20 performs demodulation processing on the first modulated signal to obtain the data contained in the first modulated signal. As a result, the second processing unit 2 can receive and obtain the data transmitted by the first processing unit 1 through the transmission line 5. The data transmitted by the first processing unit 1 can be any type of data. For example, the data transmitted by the first processing unit 1 may be control data for controlling the second processing unit 2. The sampling frequencies of the DA converter 15 of the first processing unit 1 and the AD converter 26 of the second processing unit 2 are set to, for example, twice or more the maximum value of the frequency band of the first modulated signal.

[0042] Furthermore, in data communication mode, the processing unit 20 of the second processing unit 2 generates a second transmission signal containing data. For example, the processing unit 20 generates a modulated signal digitally modulated based on the data as the second transmission signal containing data. Hereafter, the modulated signal as the second transmission signal will be referred to as the second modulated signal.

[0043] The modulation scheme of the second modulation signal may be, for example, ASK, PSK, NRZ, OFDM, or any other scheme. The DA converter 25 converts the second modulation signal from digital format to analog format and outputs the analog second modulation signal to the transmission line 5.

[0044] In the first processing device 1 that receives the second modulation signal from the transmission line 5, the AD converter 16 converts the second modulation signal from analog format to digital format and outputs the digital-format second modulation signal to the processing unit 10. The processing unit 10 performs demodulation processing on the second modulation signal to obtain the data included in the second modulation signal. Thereby, the first processing device 1 can receive and obtain the data transmitted by the second processing device 2 through the transmission line 5. The data transmitted by the second processing device 2 may be any data. For example, the data transmitted by the second processing device 2 may be sensor data acquired by the processing unit 20 from a sensor according to the control data from the first processing device 1. The sampling frequencies of the AD converter 26 of the second processing device 2 and the DA converter 15 of the first processing device 1 are set to, for example, twice or more the maximum value of the frequency band of the second modulation signal.

[0045] In the data communication mode, the resistance value of the variable termination resistor 18 (also referred to as the variable resistor 18) of the first processing device 1 and the resistance value of the variable termination resistor 28 (also referred to as the variable resistor 28) of the second processing device 2 are set to be the same as the characteristic impedance of the transmission line 5. The characteristic impedance of the transmission line 5 is, for example, 50 Ω. In the data communication mode, the resistance values of the variable resistors 18 and 28 are set to 50 Ω. Thereby, in the data communication mode, the output impedance and the input impedance of the first processing device 1 and the second processing device 2 match the characteristic impedance of the transmission line 5. Therefore, the first modulation signal transmitted by the first processing device 1 is more likely to be appropriately transmitted to the second processing device 2, and the second processing device 2 is more likely to appropriately obtain data from the second modulation signal. Similarly, the second modulation signal transmitted by the second processing device 2 is more likely to be appropriately transmitted to the first processing device 1, and the first processing device 1 is more likely to appropriately obtain data from the first modulation signal. Therefore, the communication quality between the first processing device 1 and the second processing device 2 is improved. Hereinafter, the characteristic impedance of the transmission line 5 may be referred to as the transmission line characteristic impedance. The transmission line characteristic impedance may be other than 50 Ω.

[0046] On the other hand, in the detection mode, the resistance values of the variable resistors 18 and 28 are set to be different from the transmission line characteristic impedance. That is, in the detection mode, the output impedance and input impedance of the first processing device 1 and the second processing device 2 are intentionally set to be different from the transmission line characteristic impedance. As can be understood from the following description, the detection unit 29 of the second processing device 2 can detect the state of the transmission line 5 at a low operating frequency. Therefore, the detection unit 29 can easily detect the state of the transmission line 5. Hereinafter, an operation example of the processing system 3 in the detection mode will be described in detail.

[0047] <Example of the operation of the processing system in the detection mode> Figure 2 is a flowchart showing an example of the operation of the processing system 3. In this example, when the processing system 3 is set to the data communication mode, the first processing device 1 is set to the first data communication mode in which the first processing device 1 performs data communication with the second processing device 2, and the second processing device 2 is set to the second communication mode in which the second processing device 2 performs data communication with the first processing device 1. On the other hand, when the processing system 3 is set to the detection mode, the first processing device 1 is set to the first detection mode in which the first processing device 1 performs an operation for detecting the state of the transmission line 5, and the second processing device 2 is set to the second detection mode in which the second processing device 2 detects the state of the transmission line 5.

[0048] The processing unit 10 of the first processing device 1 in the first data communication mode determines whether the detection execution condition is satisfied. In step s1, when the processing unit 10 determines that the detection execution condition is satisfied, it sets the operation mode to the first detection mode in step s2. For example, when the processing unit 10 determines that the detection execution condition is satisfied after a certain time has elapsed since the start of the previous detection process, the first processing device 1 may be set to the first detection mode. If the first processing device 1 can communicate with an external device, when the processing unit 10 determines that the first processing device 1 has received a detection execution instruction from the external device and the detection execution condition is satisfied, the first processing device 1 may be set to the first detection mode. For example, the user of the external device can operate the external device to send a detection execution instruction to the first processing device 1.

[0049] Next, in step s3, the first processing unit 1 transmits setting instruction data to the second processing unit 2 instructing it to set the second detection mode. Then, in step s4, the processing unit 10 changes the resistance value of the variable resistor 18 from 50Ω. The processing unit 10 sets the resistance value of the variable resistor 18 to, for example, 100Ω. As a result, the output impedance and input impedance of the first processing unit 1 become different from the transmission line characteristic impedance.

[0050] On the other hand, in step s11, the processing unit 20 of the second processing unit 2, which has received the setting instruction data, sets the operating mode of the second processing unit 2 to the second detection mode. As a result, the first processing unit 1 and the second processing unit 2 enter the first detection mode and the second detection mode, respectively, and the operating mode of the processing system 3 becomes the detection mode.

[0051] After step s11, in step s12, the processing unit 20 changes the resistance value of the variable resistor 28 from 50Ω. The processing unit 20 sets the resistance value of the variable resistor 28 to, for example, 100Ω. As a result, the output impedance and input impedance of the second processing unit 2 become different from the transmission line characteristic impedance.

[0052] After steps s4 and s12, in step s21, the processing system 3 executes a detection process. After the detection process is executed, step s5 is executed in the first processing unit 1 and step s15 is executed in the second processing unit 2. In step s5, the processing unit 10 sets the operating mode of the first processing unit 1 to the first data communication data. In step s15, the processing unit 20 sets the operating mode of the second processing unit 2 to the second data communication data. As a result, the first processing unit 1 and the second processing unit 2 enter the first data communication mode and the second data communication mode, respectively, and the operating mode of the processing system 3 becomes the data communication mode.

[0053] After step s5, in step s6, the processing unit 10 returns the resistance value of the variable resistor 18 to 50Ω. After step s15, in step s16, the processing unit 20 returns the resistance value of the variable resistor 28 to 50Ω. After steps s6 and s16, the first processing unit 1 and the second processing unit 2 perform data communication as necessary.

[0054] <Example of detection processing> In the detection processing of step s21, the first processing unit 1 transmits a first transmission signal (also called a detection transmission signal) to the second processing unit 2 for detecting the state of the transmission line 5. The detection transmission signal is a single-frequency signal. A single-frequency signal is also called a single-tone signal. A single-frequency signal can also be called a sine wave signal. The processing unit 10 generates a detection transmission signal in digital format, and the DA converter 15 converts the detection transmission signal generated by the processing unit 10 from digital format to analog format and outputs it to the transmission line 5. In detection mode, the first processing unit 1 functions as a transmitting device that transmits the detection transmission signal, and the second processing unit 2 functions as a receiving device that receives the detection transmission signal.

[0055] The detection unit 29 of the second processing unit 2 detects the state of the transmission line 5 based on the detection receiving signal, which is a detection transmission signal received by the second processing unit 2 from the transmission line 5. The detection receiving signal is a single-frequency signal. The detection unit 29 detects the state of the transmission line 5 based on the signal strength of the detection receiving signal.

[0056] The AD converter 26 in the detection unit 29 converts the detection received signal from analog format to digital format and outputs it. The processing unit 20 in the detection unit 29 detects the state of the transmission line 5 based on the output signal of the AD converter 26 (in other words, the detection received signal in digital format).

[0057] The detection unit 29 detects, for example, signs of a break in the transmission line 5 based on the detection received signal. The processing unit 20 detects signs of a break in the transmission line 5 based on the output signal of the AD converter 26.

[0058] Here, if a breakage is imminent in the transmission line 5, the impedance of the breakage imminent location will differ from the transmission line characteristic impedance (e.g., 50Ω). Specifically, the impedance of the breakage imminent location will be greater than the transmission line characteristic impedance. The breakage imminent location can be described as a place where there are signs of a break, or a place where a break is likely to occur. If the transmission line 5 is a stranded cable, the breakage imminent location can also be described as a place where some of the strands of the multiple strands that make up the stranded cable are broken.

[0059] In detection mode, the output impedance (in other words, transmission impedance) of the first processing unit 1, which transmits the detection transmission signal, is different from the characteristic impedance of the transmission line 5. Also, in detection mode, the input impedance (in other words, reception impedance) of the second processing unit 2, which receives the detection transmission signal, is different from the characteristic impedance of the transmission line 5. As a result, even when the frequency of the detection reception signal is low (in other words, when the frequency of the detection transmission signal is low), the influence of signs of a break in the transmission line 5 becomes more apparent in the detection reception signal. Therefore, the detection unit 29 can detect signs of a break in the transmission line 5 based on the detection reception signal at a low frequency. As a result, the detection unit 29 can detect the state of the transmission line 5 at a low operating frequency. This point will be explained in detail below. In the following explanation, as an example, it is assumed that the characteristic impedance of the transmission line is 50Ω, the length of the transmission line 5 is 3m, and the impedance at the location of the break is 100Ω. Therefore, for example, the simulation results presented in the following explanation are those obtained when the transmission line characteristic impedance is 50Ω, the length of transmission line 5 is 3m, and the impedance at the point of impending breakage is 100Ω.

[0060] Figure 3 schematically shows a transmission system 4 when the output impedance Z1 of the first processing unit 1 (in other words, the resistance value of the variable resistor 18) and the input impedance Z2 of the second processing unit 2 (in other words, the resistance value of the variable resistor 28) match the transmission line characteristic impedance. The signal source 50 shown in Figure 3 represents the processing unit 10 and the DA converter 15 that generate the first transmission signal and output it to the transmission line 5. Hereafter, the state in which the output impedance Z1 of the first processing unit 1 and the input impedance Z2 of the second processing unit 2 match the transmission line characteristic impedance may be referred to as the impedance matching state.

[0061] In the example in Figure 3, a breakage indication point 150 occurs in the center of the transmission line 5. In other words, in the example in Figure 3, a breakage indication point 150 occurs 1.5 m from the end of the 3 m long transmission line 5. Here, to simulate actual breakage indications in the cable representing the transmission line 5, the length d of the breakage indication point 150 is set to 1 cm. Hereafter, unless otherwise specified, the length d of the breakage indication point 150 occurring in the transmission line 5 will be assumed to be 1 cm.

[0062] Figures 4 and 5 are graphs showing an example of the simulation results of the frequency characteristics of the transmission characteristics of the first transmitted signal in the transmission line 5 in the example of Figure 3. Figures 4 and 5 show the transmission characteristics of the first transmitted signal in the transmission line 5 when the first processing unit 1 transmits a single-frequency first transmitted signal, such as a detection transmitted signal. Hereafter, a single-frequency first transmitted signal may be referred to as a single-frequency transmitted signal.

[0063] The horizontal axes in Figures 4 and 5 represent the frequencies of single-frequency transmission signals. The horizontal axis in Figure 4 goes up to 1 GHz, and the horizontal axis in Figure 5 goes up to 30 GHz. The vertical axes in Figures 4 and 5 represent the pass-through characteristics of the transmission path 5 for single-frequency transmission signals having the frequencies shown on the horizontal axis. In Figures 4 and 5, the S21 parameters of the transmission path 5 that transmits single-frequency transmission signals are shown as pass-through characteristics. Figures 4 and 5 show the frequency characteristics of the S21 parameters (also called S21 frequency characteristics). S21 parameters are one element included in S parameters that represent the characteristics of a circuit network. S parameters are also called scattering parameters. The S21 parameters of the transmission path 5 that transmits single-frequency transmission signals represent the ratio of the power of the single-frequency transmission signal input to the transmission path 5 to the power of the single-frequency transmission signal output from the transmission path 5.

[0064] Here, the single-frequency transmission signal received by the second processing unit 2 is referred to as the single-frequency reception signal. The S21 parameter of the transmission line 5 can be said to represent the signal strength of the single-frequency reception signal (more specifically, the relative signal strength of the single-frequency reception signal to the signal strength of the single-frequency transmission signal transmitted by the first processing unit 1). Therefore, Figures 4 and 5 can be said to represent the frequency characteristics of the signal strength of the single-frequency reception signal. The detection transmission signal and detection reception signal used in detection mode can also be said to be the single-frequency transmission signal and the single-frequency reception signal, respectively.

[0065] Since the impedance of the breakage indicator point 150 differs from the transmission line characteristic impedance, reflection of the single-frequency transmission signal occurs within the range of the breakage indicator point 150. When reflection of the single-frequency transmission signal occurs in the transmission line 5, the effect of the reflection of the single-frequency transmission signal appears in the S21 frequency characteristics (in other words, the frequency characteristics of the signal intensity of the single-frequency reception signal). Therefore, when a breakage indicator occurs in the transmission line 5, the effect of the breakage indicator appears in the S21 frequency characteristics.

[0066] In the example shown in Figure 3, the area of ​​the break warning point 150 becomes the reflection path of the single-frequency transmitted signal. Since the length of the break warning point 150 is 1 cm, reflection of the single-frequency transmitted signal occurs within this 1 cm range. Due to this reflection, the S21 frequency characteristic in the impedance-matched state comes to represent a sine wave in which a maximum or minimum peak appears for each frequency F1 corresponding to the length d of the break warning point 150. In other words, the S21 frequency characteristic in the impedance-matched state comes to represent a sine wave in which a maximum or minimum peak appears for each frequency F1 corresponding to the length of the area of ​​the break warning point 150, which is the reflection path.

[0067] Here, the time T0 required for the detection transmission signal to travel a distance a within the transmission path 5 is expressed by the following equation (1).

[0068]

[0069] In equation (1), c represents the speed of light in a vacuum, which is 300 × 10⁶ (m / s). e represents the relative permittivity of the transmission line 5 (in other words, the cable). The relative permittivity e is, for example, a value between 2 and 7.

[0070] The frequency F1 corresponding to the length d of the 150 points of potential wire breakage is expressed by the following equation (2).

[0071]

[0072] As shown in equation (2), the frequency F1 corresponding to the length d of the breakage indicator point 150 is expressed as the reciprocal of the time it takes for a single-frequency transmission signal to make one round trip over the breakage indicator point 150 of length d. For the sake of explanation, the relative permittivity e = 1 will be assumed in the following explanation.

[0073] In this example, the length d of the break point 150 is 1 cm, so the frequency F1 is 15 GHz. As shown in Figure 5, the waveform of the S21 frequency response is a sine wave with a maximum or minimum peak appearing every 15 GHz. In other words, the waveform of the frequency response of the signal strength of a single-frequency received signal is a sine wave with a maximum or minimum peak appearing every 15 GHz. The waveform of the S21 frequency response shown in Figures 4 and 5 can be said to be a sine wave with a period of 15 GHz.

[0074] Furthermore, in the impedance-matched state, if no breakage indicators 150 occur in the transmission line 5, the S21 parameter will be 0 dB at each frequency, and the waveform of the S21 frequency characteristic will be a straight line.

[0075] Hereafter, the S21 frequency characteristics shown in Figures 4 and 5, that is, the S21 frequency characteristics when a breakage indication point 150 appears in the transmission line 5 under impedance matching conditions, may be referred to as the matching / breakage indication frequency characteristics. Also, the waveform of the matching / breakage indication frequency characteristics may be referred to as the matching / breakage indication waveform.

[0076] In the frequency characteristics during matching and breakage prediction, the S21 parameter decreases from 0 dB as the frequency of the single-frequency transmission signal increases, with the first minimum peak of the S21 parameter appearing at 7.5 GHz and the first maximum peak appearing at 15 GHz. Subsequently, the maximum or minimum peak of the S21 parameter appears every 15 GHz. The waveform during matching and breakage prediction can be described as a cosine wave with a maximum value of 0 dB and a period of 15 GHz.

[0077] As shown above, the matching / disconnection prediction waveform, which represents the frequency characteristics of the S21 parameter, is a cosine wave with a period of 15 GHz. Therefore, when the frequency of the single-frequency transmission signal is relatively low, for example, 1 GHz or less, the value of the S21 parameter is -0.1 dB or less, as shown in Figure 4, and there is almost no difference from 0 dB. In other words, when the frequency of the single-frequency transmission signal is relatively low, the S21 parameter hardly changes from the value when there is no disconnection prediction point 150 in the transmission line 5 (in other words, when the transmission line 5 is normal), and the effect of the disconnection prediction is not easily apparent in the single-frequency transmission signal. Consequently, when the frequency of the single-frequency transmission signal is relatively low, it is difficult to determine from the signal strength of the single-frequency reception signal whether a disconnection prediction point 150 has occurred in the transmission line 5. In other words, when the frequency of the single-frequency transmission signal is relatively low, it is difficult to detect a disconnection prediction in the transmission line 5 based on the signal strength of the single-frequency reception signal.

[0078] On the other hand, when the frequency of the single-frequency transmission signal is a relatively high frequency, for example, in the range of 4 GHz to 11 GHz, the S21 parameter becomes -1 dB or less, as shown in Figure 5, and the difference from 0 dB is large. In other words, when the frequency of the single-frequency transmission signal is relatively high, the effects of a break in the transmission line are more likely to appear in the single-frequency transmission signal. Therefore, when the frequency of the single-frequency transmission signal is relatively high, it becomes easier to identify whether a break in the transmission line 5 is occurring based on the signal strength of the single-frequency received signal. In other words, when the frequency of the single-frequency transmission signal is relatively high, it becomes easier to detect a break in the transmission line 5 based on the signal strength of the single-frequency received signal.

[0079] However, if the frequency of the single-frequency transmission signal is high, the operating frequency of the device that detects signs of breakage in the transmission line 5 based on the signal strength of the single-frequency reception signal will also be high. This means that the device will need to be constructed with relatively expensive components, which may increase the cost of the components.

[0080] Figure 6 schematically shows an example of a transmission system 4 that includes a processing system 3 in detection mode and a transmission line 5 in which no break warning locations 150 have occurred (i.e., a normal transmission line 5). In the example in Figure 6, no break warning locations 150 have occurred in the transmission line 5. In detection mode, as described above, the output impedance Z1 and input impedance Z2 are different from the transmission line impedance. Hereafter, the state in which the output impedance Z1 and input impedance Z2 are different from the transmission line impedance will be referred to as an impedance mismatch state.

[0081] Figure 7 is a graph showing an example of the simulation results of the frequency characteristics of the transmission characteristics of the detection transmission signal in transmission line 5, as in the example in Figure 6. The horizontal axis of Figure 7 represents the frequency of the detection transmission signal, which is a single-frequency transmission signal. The vertical axis of Figure 7 shows the S21 parameters of transmission line 5, which transmits the detection transmission signal, as the transmission characteristics of the detection transmission signal in transmission line 5. Since the S21 parameters of transmission line 5, which transmits the detection transmission signal, represent the signal strength of the detection reception signal, the S21 frequency characteristics shown in Figure 7 can also be said to represent the frequency characteristics of the signal strength of the detection reception signal.

[0082] In an impedance mismatch state, if no breakage warning point 150 occurs in the transmission line 5 and the transmission line 5 is normal, reflection of the detection transmission signal occurs between one end 5a connected to the first processing unit 1 in the transmission line 5 and the other end 5b connected to the second processing unit 2 in the transmission line 5. In other words, the range from one end 5a to the other end 5b of the transmission line 5 becomes the reflection path of the detection transmission signal. As a result, the S21 frequency characteristic comes to represent a sine wave in which a maximum or minimum peak appears for each frequency F2 corresponding to the length L of the transmission line 5. The frequency F2 is expressed by the following equation (3).

[0083]

[0084] As shown in equation (3), the frequency F2 corresponding to the length L of the transmission line 5 is expressed as the reciprocal of the time it takes for the detection transmission signal to travel back and forth through the transmission line 5 of length L.

[0085] In this example, since the transmission line length L is 3m, the frequency F2 is 50MHz. As shown in Figure 7, the waveform of the S21 frequency response is a sine wave with a maximum or minimum peak appearing every 50MHz. In other words, the waveform of the frequency response of the signal strength of the detection received signal is a sine wave with a maximum or minimum peak appearing every 50MHz.

[0086] Hereafter, the S21 frequency characteristic shown in Figure 7, that is, the S21 frequency characteristic when the transmission line 5 is functioning normally under impedance mismatch conditions, may be referred to as the mismatch / normal frequency characteristic. Furthermore, the waveform of the mismatch / normal frequency characteristic may be referred to as the mismatch / normal waveform.

[0087] In the mismatched and normal frequency characteristics, the S21 parameter decreases from 0 dB as the frequency of the detection transmission signal increases, with the first minimum peak appearing at 25 MHz and the first maximum peak appearing at 50 MHz. Then, the maximum or minimum peak of the S21 parameter appears every 50 MHz. The mismatched and normal waveform, which represents the S21 frequency characteristics when the transmission line 5 is normal in an impedance mismatched state, can be said to be a cosine wave with a maximum value of 0 dB and a period of 50 MHz.

[0088] In the mismatched and normal frequency characteristics shown in Figure 7, the frequency F3 at which the S21 parameter reaches its minimum peak is given by the following equation (4).

[0089]

[0090] Here, the parameter N in equation (4) represents an integer greater than or equal to 0. For example, when N = 0, frequency F3 is the frequency at which the S21 parameter first reaches its minimum peak in the mismatched and normal frequency characteristics. Frequency F3 can also be said to be the frequency at which the signal strength reaches its minimum peak in the frequency characteristics of the signal strength of the detection received signal when the transmission line 5 is normal in the impedance mismatched state.

[0091] Figure 8 is a schematic diagram showing a transmission system 4 that includes a processing system 3 in detection mode and a transmission line 5 where a breakage indication point 150 has occurred. In the example in Figure 8, similar to the example in Figure 3, a breakage indication point 150 with a length of 1 cm has occurred in the center of the transmission line 5.

[0092] Figure 9 is a graph showing an example of the simulation results of the frequency characteristics of the transmission characteristics of the detection transmission signal in the transmission line 5 in the example of Figure 8. In Figure 9, the S21 frequency characteristics in the example of Figure 8, that is, the S21 frequency characteristics when a breakage precursor point 150 occurs in the transmission line 5 under impedance mismatch conditions, are shown by a relatively thick line. Also in Figure 9, the S21 frequency characteristics in the example of Figure 6, that is, the frequency characteristics under mismatch and normal conditions, are shown by a relatively thin line. Hereafter, the S21 frequency characteristics when a breakage precursor point 150 occurs in the transmission line 5 under impedance mismatch conditions may be referred to as the mismatch / breakage precursor frequency characteristics. Also, the waveform of the mismatch / breakage precursor frequency characteristics may be referred to as the mismatch / breakage precursor waveform.

[0093] When a break point 150 occurs in the transmission line 5 under impedance mismatch conditions, the detection transmission signal will be reflected in the transmission line 5 at one end 5a of the transmission line 5, the other end 5b of the transmission line 5, one end 151 of the break point 150 on the first processing unit 1 side, and the other end 152 of the break point 150 on the second processing unit 2 side. As a result, in the transmission line 5, various reflections of the detection transmission signal occur in addition to the reflection between one end 5a and the other end 5b. For example, as in the example in Figure 3, the detection transmission signal is reflected within the range of the break point 150. Also, the detection transmission signal from one end 5a of the transmission line 5 toward the break point 150 may be reflected at one end 151 of the break point 150, or it may pass through one end 151 and be reflected at the other end 152 of the break point 150. Furthermore, the detection transmission signal that is reflected at the other end 5b of the transmission line 5 and heads towards the breakage indication location 150 may be reflected at the other end 152 of the breakage indication location 150, or it may pass through the other end 152 and be reflected at one end 151 of the breakage indication location 150.

[0094] Thus, when a breakage indication point 150 occurs in the transmission line 5 under impedance mismatch conditions, various reflections occur in the transmission line 5 with respect to the reflection of the detected transmission signal, in addition to the reflection between one end 5a and the other end 5b. As a result, as shown in Figure 9, the waveform during mismatch / breakage indication (thick line waveform) differs from the waveform during mismatch / normal operation (thin line waveform).

[0095] Figure 10 is a schematic diagram of a transmission system 4 that includes a processing system 3 in detection mode and a transmission line 5 where a breakage indication point 150 has occurred. In the example in Figure 10, a breakage indication point 150 with a length of 1 cm has occurred in the transmission line 5 at a location 1 m from one end 5a. Figure 11 is a graph showing the simulation results of the frequency characteristics during mismatch / breakage indication in the example in Figure 10. Figure 12 is a graph showing the simulation results of the frequency characteristics during mismatch / breakage indication when a breakage indication point 150 with a length of 1 cm occurs at a location 0.7 m from one end 5a in the transmission line 5. In Figures 11 and 12, the frequency characteristics during mismatch / breakage indication are shown by relatively thick lines, and the frequency characteristics during mismatch / normal operation are shown by relatively thin lines.

[0096] As shown in Figures 9, 11, and 12, the waveform during a mismatch / breakout warning is similar to the waveform during a mismatch / normal state, with alternating maximum and minimum peaks. Furthermore, the waveform during a mismatch / breakout warning generally has a minimum peak that changes in a similar manner to the waveform during a match / breakout warning (see Figures 4 and 5). In other words, the waveform during a mismatch / breakout warning generally has a minimum peak that changes in a similar manner to the changes of a cosine wave with a period of 15 GHz.

[0097] In the waveforms during matched / disconnection prediction, as shown in Figures 4 and 5, the S21 parameter gradually decreases up to a frequency of 7.5 GHz. Correspondingly, in the waveforms during mismatch / disconnection prediction, the minimum peak generally gradually increases in the negative direction up to a frequency of 7.5 GHz. The dashed lines in Figures 9, 11, and 12 show that the minimum peak of the waveform during mismatch / disconnection prediction gradually increases in the negative direction overall. Furthermore, even if the frequency of the detection transmission signal is relatively low, for example, below 1 GHz, the difference between the waveform during mismatch / disconnection prediction (thick line) and the waveform during mismatch / normal operation (thin line) becomes more apparent, and the influence of the disconnection prediction becomes more apparent in the waveform during mismatch / disconnection prediction. In particular, when the frequency of the detection transmission signal is the frequency F3 at which the minimum peak appears in the waveform during mismatch / normal operation, the absolute value Δ1 of the difference between the waveform during mismatch / disconnection prediction and the waveform during mismatch / normal operation (see Figures 9, 11, and 12) tends to increase. Therefore, when the frequency of the detection transmission signal is frequency F3, the signal strength of the detection reception signal is more likely to be affected by the signs of a potential disconnection.

[0098] Although it is unlikely to actually occur, Figure 13 shows, for reference, the simulation results of the frequency characteristics during mismatch / predicted breakage when a breakage precursor point 150 with a length d of 20 cm occurs in the center of the transmission line 5. When the length d of the breakage precursor point 150 is 20 cm, the frequency F1 corresponding to the length d of the breakage precursor point 150, which is the period of the waveform during matching / predicted breakage, is 750 MHz according to equation (2). Therefore, the waveform during matching / predicted breakage is a cosine wave with one period of 750 MHz. Thus, as shown in Figure 13, when a breakage precursor point 150 with a length d of 20 cm occurs in the transmission line 5, the minimum peak of the waveform during mismatch / predicted breakage gradually increases in the negative direction up to a frequency of 375 MHz, and gradually increases in the positive direction from a frequency of 375 MHz to 750 MHz.

[0099] Thus, even if the frequency of the detection transmission signal is relatively low, for example, 1 GHz or less, the effects of the pre-disconnection are more likely to appear in the waveform during mismatch / disconnection prediction. Therefore, even when the frequency of the detection transmission signal is low, the effects of the pre-disconnection of the transmission line 5 are more likely to appear in the detection reception signal. As a result, in the detection process, the detection unit 29 can detect pre-disconnection based on the detection reception signal even when the frequency of the detection transmission signal is relatively low.

[0100] Figure 14 is a flowchart showing an example of the detection process in step s21. In the detection process, the first processing unit 1 changes the frequency of the detection transmission signal, for example. Then, the detection unit 29 of the second processing unit 2 detects an indication of a break in the transmission line 5 based on a detection reception signal corresponding to multiple values ​​of the frequency of the detection transmission signal. Hereafter, when referring to the transmission frequency, it means the frequency of the detection transmission signal.

[0101] In the detection process, the first processing unit 1 changes the transmission frequency M times (where M is an integer of 2 or more) within a range of, for example, 1 GHz or less. In this case, there are M transmission frequencies. As described above, when the frequency of the detection transmission signal is set to frequency F3, the effects of the breakage prediction are more likely to appear in the waveform during mismatch / breakage prediction. Therefore, the first processing unit 1 sets the transmission frequency to frequency F3 within a range of 1 GHz or less. The first processing unit 1 changes the transmission frequency M times within a range of 1 GHz or less by changing the parameter N that defines the value of frequency F3 M times. As can be understood from equations (4) and (3) above, since frequency F3 changes according to the length L of the transmission line 5, when the transmission frequency is set to frequency F3, it can be said that the transmission frequency is a value based on the length L of the transmission line 5.

[0102] As shown in Figures 9, 11, and 12, when the transmission frequency is quite low, the difference between the waveform during mismatch / disconnection prediction and the waveform during mismatch / normal operation is less apparent. Therefore, the minimum value of the transmission frequency may be set to a frequency equal to or higher than the reciprocal of the time it takes for the detection transmission signal to travel from one end 5a to the other end 5b of the transmission line 5. In other words, the first processing unit 1 may set the transmission frequency to a frequency equal to or higher than the reciprocal of the time it takes for the detection transmission signal to travel from one end 5a to the other end 5b of the transmission line 5. It can also be said that the first processing unit 1 sets the transmission frequency to a frequency equal to or higher than the reciprocal of the time it takes for the detection transmission signal to travel a distance L along the transmission line 5.

[0103] From equation (1) above, in this example, the frequency equal to the reciprocal of the time it takes for the detection transmission signal to travel from one end 5a to the other end 5b of the transmission line 5 is 100 MHz. In other words, the frequency equal to the reciprocal of the time it takes for the detection transmission signal to travel along the transmission line 5 over a length L is 100 MHz. In the detection process, the minimum value of the transmission frequency is set to 100 MHz or higher.

[0104] In the detection process, the first processing unit 1 changes the value of parameter N 18 times by decreasing it by one, for example, from 19 to 2. In this case, M = 18, the maximum transmission frequency becomes 975 MHz, and the minimum transmission frequency becomes 125 MHz. In the detection process, the first processing unit 1 transmits a detection transmission signal at M transmission frequencies. In the detection process, the first processing unit 1 transmits a detection transmission signal M times by changing the transmission frequency.

[0105] Before the detection process is executed, the first processing unit 1 notifies the second processing unit 2 in advance how the transmission frequency will be changed during the detection process. In other words, the first processing unit 1 notifies the second processing unit 2 in advance the transmission frequency for each time the detection transmission signal is transmitted. For example, in step s3 of Figure 2, the first processing unit 1 transmits transmission frequency data to the second processing unit 2, along with setting instruction data, indicating how the transmission frequency will be changed. In the transmission frequency data, for each of the M transmission frequencies, the transmission frequency and the order in which the detection transmission signal having that transmission frequency is transmitted (i.e., in which of the M transmissions it is transmitted) are associated with each other. The detection unit 29 of the second processing unit 2 can recognize how the transmission frequency will be changed during the detection process from the transmission frequency data received by the second processing unit 2. By the first processing unit 1 transmitting the transmission frequency data to the second processing unit 2 before the detection process is executed, the second processing unit 2 can recognize the transmission frequency of the detection transmission signal in advance before receiving the detection transmission signal.

[0106] Alternatively, instead of the first processing unit 1 transmitting the transmission frequency data to the second processing unit 2, the storage unit 21 of the second processing unit 2 may store the transmission frequency data in advance. In this case, the second processing unit 2 will recognize in advance the transmission frequency for each time the detection transmission signal is transmitted. In this case, it can also be said that the second processing unit 2 recognizes the transmission frequency of the detection transmission signal in advance before receiving the detection transmission signal.

[0107] In this way, because the second processing unit 2 recognizes the transmission frequency of the detection transmission signal in advance before receiving the detection transmission signal, the second processing unit 2 can easily detect the state of the transmission line 5.

[0108] In the detection process, as shown in Figure 14, step s51 is executed M times. In step s51, steps s31 and s41 are executed. In the detection process, step s31 is executed M times and step s41 is executed M times. In step s31, the first processing unit 1 transmits a detection transmission signal. In step s41, the detection unit 29 of the second processing unit 2 acquires the signal strength of a detection reception signal corresponding to the detection transmission signal transmitted in step s31. The detection reception signal corresponding to the detection transmission signal is the detection transmission signal received by the second processing unit 2.

[0109] In the mth step s31, the first processing unit 1 sets the value of parameter N to (20 - m), where m is an integer between 1 and M. Therefore, in the first step s31 of the detection process, a detection transmission signal with a transmission frequency of 975 MHz is transmitted. In the final Mth step (i.e., the 18th) of step s31, a detection transmission signal with a transmission frequency of 125 MHz is transmitted. During the detection process, the first processing unit 1 decreases the transmission frequency by 50 MHz increments from 975 MHz to 125 MHz.

[0110] Hereafter, the detection transmission signal transmitted in the mth step s31 may be referred to as the mth detection transmission signal. The detection reception signal corresponding to the mth detection transmission signal, that is, the detection reception signal which is the mth detection transmission signal received by the second processing unit 2, may be referred to as the mth detection reception signal. Furthermore, the transmission frequency of the mth detection transmission signal may be referred to as the mth transmission frequency.

[0111] In the mth step s41, the AD converter 26 of the detection unit 29 converts the mth detection received signal from analog format to digital format and outputs it. Then, the processing unit 20 of the detection unit 29 obtains the signal strength of the mth detection received signal based on the output signal of the AD converter 26.

[0112] When an AD converter converts a single-frequency input signal from analog to digital, the sampling frequency of the AD converter is generally set to at least twice the frequency of the input signal. Since half the sampling frequency is called the Nyquist frequency, the Nyquist frequency of the AD converter is generally set to at least the frequency of the input signal.

[0113] As described above, in this example, the maximum transmission frequency is 975 GHz. Therefore, if the Nyquist frequency of the AD converter 26 is set to a frequency higher than the transmission frequency, the sampling frequency of the AD converter 26 will be 1.95 GHz or higher, requiring an expensive AD converter 26.

[0114] Therefore, the detection unit 29 in this example is configured to acquire the signal strength of the detection receiving signal according to multiple values ​​of the changing transmission frequency, while setting the Nyquist frequency of the AD converter 26 to a value lower than the maximum value of the transmission frequency. As a result, the detection unit 29 can detect the state of the transmission line 5 at a low operating frequency, and the state of the transmission line 5 can be easily detected.

[0115] In this example, the Nyquist frequency of the AD converter 26 is set to 125 MHz, which is lower than the maximum transmission frequency of 975 GHz. In other words, the sampling frequency of the AD converter 26 is set to 250 MHz. This 250 MHz is greater than twice the maximum frequency bandwidth of the first modulated signal transmitted by the first processing unit 1. Hereafter, when we simply refer to the Nyquist frequency and the sampling frequency, we are referring to the Nyquist frequency and the sampling frequency of the AD converter 26, respectively.

[0116] In the m-th step s41, if the m-th transmission frequency (in other words, the frequency of the m-th detection receiving signal) is less than or equal to the Nyquist frequency, the processing unit 20 of the detection unit 29 obtains the signal strength of the frequency component corresponding to the m-th detection receiving signal (also called the original signal corresponding frequency component) included in the output signal of the AD converter 26 as the signal strength of the m-th detection receiving signal. The original signal corresponding frequency component is a frequency component included in the output signal of the AD converter 26 that has the same frequency as the m-th transmission frequency. The processing unit 20 can obtain the signal strength of the original signal corresponding frequency component by performing a Fourier transform (specifically a discrete Fourier transform) on the output signal of the AD converter 26.

[0117] On the other hand, if the m-th transmission frequency is greater than the Nyquist frequency, the processing unit 20 obtains the signal strength of the alias component having a frequency below the Nyquist frequency included in the output signal of the AD converter 26 as the signal strength of the m-th detection reception signal. The processing unit 20 can obtain the signal strength of the alias component having a frequency below the Nyquist frequency by performing a Fourier transform on the output signal of the AD converter 26.

[0118] Figure 15 is a schematic diagram showing an example of the frequency spectra of the input signal (i.e., the analog detection receiving signal) and output signal (i.e., the digital detection receiving signal) of the AD converter 26 when the transmission frequency is below the Nyquist frequency. Figures 16 and 17 are schematic diagrams showing an example of the frequency spectra of the input signal and output signal of the AD converter 26 when the transmission frequency is greater than the Nyquist frequency. The frequency spectrum of the input signal of the AD converter 26 is shown in the upper part of Figures 15 to 17, and the frequency spectrum of the output signal of the AD converter 26 is shown in the lower part of Figures 15 to 17. In Figures 15 to 17, Fin indicates the frequency of the input signal of the AD converter 26. The frequency Fin matches the transmission frequency and the frequency of the detection receiving signal. In Figures 15 to 17, Fs indicates the sampling frequency of the AD converter 26. In the example of Figure 15, the transmission frequency (in other words, the frequency Fin of the input signal of the AD converter 26) is included in the first Nyquist zone. In the example of Figure 16, the transmission frequency is included in the second Nyquist zone. In the example shown in Figure 17, the transmission frequency falls within the third Nyquist zone. Hereafter, the input signal of the AD converter 26 may be referred to as the AD input signal, and the output signal of the AD converter 26 may be referred to as the AD output signal.

[0119] As shown in Figures 15 to 17, the AD output signal includes multiple alias components 201 in addition to the original signal-corresponding frequency component 200, which corresponds to the detection receiving signal (in other words, the AD input signal) input to the AD converter 26. The alias components 201 appear in each Nyquist zone other than the Nyquist zone to which the original signal-corresponding frequency component 200 belongs. In the example in Figure 15, the alias components 201 appear in each Nyquist zone other than the first Nyquist zone to which the original signal-corresponding frequency component 200 appears. In the example in Figure 16, the alias components 201 appear in each Nyquist zone other than the second Nyquist zone to which the original signal-corresponding frequency component 200 appears. In the example in Figure 17, the alias components 201 appear in each Nyquist zone other than the third Nyquist zone to which the original signal-corresponding frequency component 200 appears.

[0120] Since the original signal-corresponding frequency component 200 corresponds to the detection-receiving signal, regardless of the transmission frequency (in other words, regardless of frequency Fin), the processing unit 20 may acquire the signal strength of the original signal-corresponding frequency component 200 as the signal strength of the detection-receiving signal.

[0121] However, in the frequency characteristics of the gain of the AD converter 26 alone, due to the aperture effect, the gain attenuates according to the sin function as the frequency increases. Therefore, in the frequency characteristics of the gain of the AD converter 26 alone, the gain does not attenuate much from 0 dB below the Nyquist frequency (i.e., the first Nyquist zone), but it attenuates significantly above the Nyquist frequency. As a result, when the transmission frequency is greater than the Nyquist frequency, if the signal strength of the frequency component corresponding to the original signal is obtained as the signal strength of the detection receiving signal, there is a possibility that the signal strength of the detection receiving signal may not be obtained correctly. Therefore, regardless of the transmission frequency, if the signal strength of the frequency component corresponding to the original signal is used as the signal strength of the detection receiving signal, the Nyquist frequency must be set to be greater than or equal to the maximum value of the transmission frequency in order to correctly obtain the signal strength of the detection receiving signal. In this case, an expensive AD converter 26 is required.

[0122] Therefore, in this example, if the transmission frequency is below the Nyquist frequency, the processing unit 20 acquires the signal strength of the frequency component corresponding to the original signal as the signal strength of the detection receiving signal. On the other hand, if the transmission frequency is greater than the Nyquist frequency, the processing unit 20 acquires the signal strength of the alias component appearing below the Nyquist frequency (i.e., the alias component appearing in the first Nyquist zone) as the signal strength of the detection receiving signal. This makes it possible to correctly acquire the signal strength of the detection receiving signal according to multiple values ​​of the transmission frequency using the AD converter 26 with a small Nyquist frequency.

[0123] Figures 18 and 19 are graphs showing an example of the frequency characteristics of the signal strength of an AD input signal when the signal strength of the AD input signal is acquired based on the AD output signal using a standalone AD converter 26 with a sampling frequency of 250 MHz. The horizontal axis of Figures 18 and 19 represents the frequency Fin of the AD input signal. The vertical axis of Figures 18 and 19 represents the signal strength of the AD input signal acquired based on the AD output signal. Figure 18 shows an example of the frequency characteristics of the signal strength of an AD input signal when the signal strength of the original signal-corresponding frequency component included in the AD output signal is used as the signal strength of the AD input signal, regardless of the frequency Fin of the AD input signal. Figure 19 shows an example of the frequency characteristics of the signal strength of an AD input signal when the signal strength of the original signal-target component included in the AD output signal is used as the signal strength of the AD input signal when the frequency Fin is less than or equal to the Nyquist frequency, and when the frequency Fin is greater than the Nyquist frequency, the signal strength of the alias component below the Nyquist frequency included in the AD output signal is used as the signal strength of the AD input signal.

[0124] In the example in Figure 18, the signal strength of the AD input signal acquired based on the AD output signal attenuates according to the sin function as the frequency increases, and attenuates significantly above the Nyquist frequency (Fs / 2). On the other hand, in the example in Figure 19, the signal strength of the AD input signal acquired based on the AD output signal remains approximately constant regardless of the frequency Fin.

[0125] If the frequency Fin of the input signal of the AD converter 26 falls within the pth Nyquist zone (P is an integer greater than or equal to 2) which is greater than the Nyquist frequency, the frequency Fa of the alias component appearing in the first Nyquist zone is expressed by the following equation (5) when P is odd. In other words, if the frequency Fin belongs to the third or later odd-numbered Nyquist zone, the frequency Fa is expressed by the following equation (5).

[0126]

[0127] When P is even, that is, when the frequency Fin belongs to an even-numbered Nyquist zone, the frequency Fa is expressed by the following equation (6).

[0128]

[0129] Since the frequency Fin of the input signal of the AD converter 26 matches the transmission frequency, equations (5) and (6) can be said to show the relationship between the transmission frequency and the frequency Fa of the alias component that appears in the first Nyquist zone. The frequency of the alias component is also called the alias frequency.

[0130] In the m-th step s41, the processing unit 20 identifies the m-th transmission frequency from the transmission frequency data in the storage unit 21. If the identified transmission frequency is less than or equal to the Nyquist frequency, the processing unit 20 performs a Fourier transform on the output signal of the AD converter 26 and obtains the signal strength of the frequency component having the same frequency as the identified transmission frequency (i.e., the frequency component corresponding to the original signal) as the signal strength of the m-th detection receiving signal. On the other hand, if the identified transmission frequency is greater than the Nyquist frequency, the processing unit 20 identifies the Nyquist zone to which the identified transmission frequency belongs. If the Nyquist zone to which the identified transmission frequency belongs is an odd-numbered Nyquist zone, the processing unit 20 uses the identified transmission frequency and equation (5) to identify the alias frequency Fa of the alias component appearing in the first Nyquist zone. It can also be said that the processing unit 20 identifies an alias frequency Fa less than or equal to the Nyquist frequency for the alias component included in the output signal of the AD converter 26. Furthermore, if the Nyquist zone to which the identified transmission frequency belongs is an even-numbered Nyquist zone, the processing unit 20 uses the identified transmission frequency and equation (6) to identify the alias frequency Fa of the alias component appearing in the first Nyquist zone. The processing unit 20 then performs a Fourier transform on the output signal of the AD converter 26 to obtain the signal strength of the alias component having the identified alias frequency Fa as the signal strength of the m-th detection received signal.

[0131] Thus, when the transmission frequency is greater than the Nyquist frequency of the AD converter 26, the detection unit 29 identifies an alias frequency Fa less than or equal to the Nyquist frequency for the alias component included in the output signal of the AD converter 26 based on the transmission frequency. The detection unit 29 then acquires the signal strength of the alias component having the identified alias frequency Fa as the signal strength of the m-th detection received signal. This makes it possible to correctly acquire the signal strength of the detection received signal using the AD converter 26 with a low sampling frequency. Therefore, the detection unit 29 can detect the state of the transmission line 5 at a low operating frequency, and the state of the transmission line 5 can be easily detected.

[0132] Furthermore, even if the sampling frequency is set to a high value, for example, around 1.95 GHz, and the transmission frequency is greater than the Nyquist frequency, the processing unit 20 may acquire the signal strength of the original signal-corresponding frequency component included in the AD output signal as the signal strength of the detection received signal.

[0133] When step s51 is executed M times, in step s42, the processing unit 20 executes a first detection process to detect the state of the transmission line 5 based on the signal strength of the detection received signal acquired in step s41 M times. In the first detection process, signs of a break in the transmission line 5 are detected.

[0134] In this example, the minimum peak signal strength in the frequency characteristics of the detection received signal when there is impedance mismatch and the transmission line 5 is functioning normally is stored in the storage unit 21 as the reference minimum peak signal strength. The reference minimum peak signal strength may be a measured value or a simulated value. The reference minimum peak signal strength can be said to be the signal strength of the detection received signal when there is impedance mismatch and the transmission line 5 is functioning normally, and the transmission frequency is frequency F3. The reference minimum peak signal strength corresponds to the S21 parameter of the minimum peak in the mismatch / normal frequency characteristics shown in Figure 7.

[0135] In the first detection process, the processing unit 20 determines a first determination value for determining whether a break in the transmission line 5 is occurring, based on the signal strength of the detection received signals acquired M times and the reference minimum peak signal strength. For example, for each of the signal strengths of the detection received signals acquired M times, the processing unit 20 acquires the absolute value of the difference between that signal strength and the reference minimum peak signal strength. This absolute value of the difference corresponds to the absolute value Δ1 of the difference shown in Figures 9, 11, and 12. The processing unit 20 acquires M absolute values ​​of the differences. The processing unit 20 then uses the sum of the M absolute values ​​of the acquired differences as the first determination value. If the acquired first determination value is greater than or equal to a threshold, the processing unit 20 determines that a break in the transmission line 5 is occurring. On the other hand, if the acquired first determination value is less than a threshold, the processing unit 20 determines that there is no break in the transmission line 5, that is, the transmission line 5 is normal.

[0136] When the first detection process in step s42 is completed, in step s43, the second processing unit 2 generates detection result data indicating the detection result of the transmission line 5 breakage precursor (in other words, the result of the first detection process), and transmits the generated detection result data to the first processing unit 1. This completes the detection process.

[0137] The first processing unit 1, upon receiving the detection result data, performs processing based on the detection result data. For example, if the first processing unit 1 is equipped with a display unit such as a liquid crystal display, the first processing unit 1 may display the detection result indicated by the detection result data on the display unit. In this case, the user of the first processing unit 1 can confirm from the display unit whether or not there is a sign of a break in the transmission line 5. The first processing unit 1 may also transmit the detection result data to an external device. The external device may display the detection result indicated by the received detection result data.

[0138] In the transmission frequency data, for transmission frequencies greater than the Nyquist frequency among the M transmission frequencies, the alias frequency Fa corresponding to that transmission frequency and the order in which the detection transmission signal having that transmission frequency is transmitted may be associated with each other. The alias frequency Fa corresponding to a transmission frequency greater than the Nyquist frequency means the alias frequency Fa of the alias component appearing in the first Nyquist zone, included in the AD output signal corresponding to the detection transmission signal having that transmission frequency. In the m-th step s41, if the transmission frequency is associated with the m-th transmission frequency in the transmission frequency data in the storage unit 21, the processing unit 20 acquires the signal strength of the frequency component corresponding to the original signal as the signal strength of the m-th detection reception signal. On the other hand, if the alias frequency Fa is associated with the m-th transmission frequency in the transmission frequency data (i.e., the m-th transmission frequency is greater than the Nyquist frequency), the processing unit 20 acquires the signal strength of the alias component having that alias frequency Fa as the signal strength of the m-th detection reception signal. When the first processing unit 1 transmits transmission frequency data to the second processing unit 2, the first processing unit 1 notifies the second processing unit 2 of the transmission frequencies among the M transmission frequencies that are less than or equal to the Nyquist frequency, and notifies the second processing unit 2 of the alias frequency Fa corresponding to the transmission frequencies among the M transmission frequencies that are greater than the Nyquist frequency. On the other hand, when the storage unit 21 stores the transmission frequency data, the second processing unit 2 recognizes in advance the transmission frequencies among the M transmission frequencies that are less than or equal to the Nyquist frequency, and also recognizes in advance the alias frequency Fa corresponding to the transmission frequencies among the M transmission frequencies that are greater than the Nyquist frequency.

[0139] In the example shown in Figure 14, the second processing unit 2 acquires the signal strength of the received detection signal each time it receives a transmission detection signal. However, it is also possible to acquire the signal strength of the received detection signal M times after receiving the transmission detection signal M times.

[0140] Furthermore, in the above example, when the first processing unit 1 changes the transmission frequency in the detection process, it decreases the transmission frequency from 975 MHz, but it may also increase the transmission frequency from 125 MHz.

[0141] As described above, in the frequency characteristics of the gain of the AD converter 26 alone, the gain attenuates according to the sin function due to the aperture effect. The gain attenuates to some extent even below the Nyquist frequency.

[0142] Therefore, the processing unit 20 may perform a correction process on the signal strength of the detection received signal acquired based on the AD output signal to correct for attenuation due to the aperture effect. Then, the processing unit 20 may detect the state of the transmission line 5 based on the signal strength of the detection received signal after the correction process. This allows the processing unit 20 to acquire a more accurate signal strength for the detection received signal and to more accurately detect the state of the transmission line 5 (in this example, a break in the line). In the first detection process, for example, the processing unit 20 calculates the absolute value of the difference between the corrected signal strength and the reference minimum peak signal strength for each of the M corrected signal strengths for the detection received signal. Then, the processing unit 20 sets the sum of the absolute values ​​of the obtained M differences as the first determination value.

[0143] When the processing unit 20 performs correction processing, for example, the amount of attenuation of the signal strength of the detection received signal due to the aperture effect at each frequency below the Nyquist frequency (in other words, the amount of attenuation according to the sin function) is stored in the storage unit 21. The amount of attenuation is a theoretical value. When the processing unit 20 performs correction processing on the signal strength of the m-th detection received signal, if the transmission frequency of the m-th signal is below the Nyquist frequency, it obtains the amount of attenuation at the same frequency as the transmission frequency of the m-th signal from the storage unit 21. Then, the processing unit 20 adds the obtained amount of attenuation to the signal strength of the m-th detection received signal to correct the attenuation due to the aperture effect. On the other hand, if the transmission frequency of the m-th signal is greater than the Nyquist frequency, the processing unit 20 obtains the amount of attenuation at the same frequency as the alias frequency Fa below the Nyquist frequency from the storage unit 21. Then, the processing unit 20 adds the obtained amount of attenuation to the signal strength of the alias component below the Nyquist frequency, which was obtained as the signal strength of the m-th detection received signal, to correct the attenuation due to the aperture effect.

[0144] The first processing unit 1 may acquire the length L of the transmission line 5 and set the transmission frequency based on the acquired length L. Figure 20 is a schematic diagram showing an example of the processing system 3 in this case.

[0145] In the processing system 3 (also referred to as processing system 3a) shown in Figure 20, the detection unit 29 includes a switch circuit 27 that switches whether or not to connect one end of a variable resistor 28 to the output of the DA converter 25 and the input of the AD converter 26. When the switch circuit 27 is ON, one end of the variable resistor 28 is connected to the output of the DA converter 25 and the input of the AD converter 26. As a result, the input impedance of the second processing unit 2 becomes the resistance value of the variable resistor 28. On the other hand, when the switch circuit 27 is OFF, the input impedance of the second processing unit 2 becomes infinite. The processing unit 20 can control the switch circuit 27 to set it to the ON state or the OFF state.

[0146] In addition to the data communication mode and the detection mode, the processing system 3a includes an acquisition mode for acquiring the length L of the transmission path 5. In the acquisition mode, the first processing unit 1 acquires the length L of the transmission path 5 using, for example, the TDR (Time Domain Reflectometry) method.

[0147] For example, when the processing system 3a starts operating for the first time after its introduction, the processing system 3a first operates in acquisition mode. In acquisition mode, the first processing unit 1 transmits off instruction data to the second processing unit 2, instructing it to turn off the switch circuit 27. Upon receiving the off instruction data, the second processing unit 20 turns off the switch circuit 27. Next, the first processing unit 1 transmits a single pulse signal as, for example, the first transmission signal. At this time, since the input impedance of the second processing unit 2 is infinite, the single pulse signal undergoes total reflection at the second processing unit 2 and returns to the first processing unit 1 through the transmission line 5. The processing unit 10 of the first processing unit 1 acquires the time T1 from the time the single pulse signal is transmitted until the single pulse signal is reflected back by the second processing unit 2. Time T1 is the time it takes for the single pulse signal to make one round trip through the transmission line 5. Based on the acquired time T1, the processing unit 10 acquires the length L of the transmission line 5. The processing unit 10 acquires the length L using the following equation (7).

[0148]

[0149] When the processing unit 10 acquires the length L, the first processing unit 1 transmits ON instruction data to the second processing unit 2, instructing it to turn on the switch circuit 27. Upon receiving the ON instruction data, the second processing unit 20 turns on the switch circuit 27. Subsequently, the operating mode of the processing system 3a changes from acquisition mode to data communication mode.

[0150] When the processing system 3a performs detection processing, the processing unit 10 sets the transmission frequency based on the length L acquired in acquisition mode. For example, in step s3 of Figure 2, the processing unit 10 uses the acquired length L and equations (3) and (4) to determine M values ​​of frequency F3 while changing the parameter N. Then, the processing unit 10 generates transmission frequency data using the M values ​​obtained as the transmission frequency. The transmission frequency data generated by the processing unit 10 is transmitted to the second processing unit 2.

[0151] The content of the detection process is not limited to the above example. For example, the first processing unit 1 may transmit a detection transmission signal at at least one frequency, and the detection unit 29 may perform a process to detect the state of the transmission line 5 based on a detection reception signal corresponding to the detection transmission signal transmitted at at least one frequency. If the state of the transmission line 5 is not detected in this process, the first processing unit 1 may retransmit the detection transmission signal at at least one frequency different from the previous one, and the detection unit 29 may perform a process to detect the state of the transmission line 5 based on a detection reception signal corresponding to the retransmitted detection transmission signal. Figure 21 is a flowchart showing an example of the operation of the second processing unit 2 in this case.

[0152] In the detection process of this example, the first processing unit 1 executes step s31 a maximum of M times and a minimum of 1 time. During the detection process, the first processing unit 1 transmits a detection transmission signal a maximum of M times and a minimum of 1 time.

[0153] In the detection process, when the first processing unit 1 transmits the first detection transmission signal (for example, a detection transmission signal of 975 MHz), the second processing unit 2 receives the first detection transmission signal in step s61 shown in Figure 21.

[0154] Next, in step s62, the processing unit 20 acquires the signal strength of the first detection received signal, similar to step s41 above. Next, in step s63, the processing unit 20 performs a second detection process to detect the state of the transmission line 5 based on the acquired signal strength of the first detection received signal. In the second detection process, the processing unit 20 acquires the absolute value of the difference between the signal strength of the first detection received signal and the above-mentioned minimum reference peak signal strength as the second determination value. Then, if the second determination value is greater than or equal to the threshold, the processing unit 20 determines that a break in the transmission line 5 is imminent. In other words, in the second detection process, the processing unit 20 determines that a break in the transmission line 5 has been detected. On the other hand, if the second determination value is less than the threshold, the processing unit 20 determines that no break in the transmission line 5 has been detected.

[0155] If a break in the transmission line 5 is detected in the second detection process (YES in step s64), in step s65, the processing unit 20 generates data indicating that a break in the transmission line 5 is imminent. The second processing unit 2 then transmits the data to the first processing unit 1. This completes the detection process.

[0156] The first processing unit 1, upon receiving the data indicating a potential disconnection, may display information on its display unit indicating that a potential disconnection has occurred in the transmission line 5, or it may transmit the data indicating a potential disconnection to an external device. The external device, upon receiving the data indicating a potential disconnection, may also display information indicating that a potential disconnection has occurred in the transmission line 5.

[0157] If no indication of a break in the transmission line 5 is detected in the second detection process (NO in step s64), step s66 is executed. In step s66, it is determined that the processing unit 20 has received the detection transmission signal M times. If NO is determined in step s66, step s67 is executed. On the other hand, if YES is determined in step s66, step s68 is executed.

[0158] In step s67, the processing unit 20 generates transmission instruction data that instructs the transmission of a detection transmission signal. The second processing unit 2 then transmits the transmission instruction data to the first processing unit 1.

[0159] Upon receiving the transmission instruction data, the first processing unit 1 transmits the next detection transmission signal, in this case the second detection transmission signal. The second processing unit 2 receives the second detection transmission signal in step s61. Subsequently, steps s62 and s63 are executed using the second detection transmission signal. If a break in the transmission line 5 is detected in the second detection process (YES in step s64), step s65 is executed and data indicating a break is transmitted. This completes the detection process. On the other hand, if no break in the transmission line 5 is detected in the second detection process (NO in step s64), step s66 is executed. If NO is determined in step s66, step s67 is executed. This causes the first processing unit 1 to transmit the next detection transmission signal. Thereafter, the processing system 3 operates similarly.

[0160] In step s66, if the second processing unit 2 determines that it has received the detection transmission signal M times (YES in step s66), the processing unit 20 determines that there is no indication of a break in the transmission line 5 and generates data indicating that there is no indication of a break in the transmission line 5. The second processing unit 2 then transmits the data indicating no indication to the first processing unit 1. This completes the detection process.

[0161] The first processing unit 1, upon receiving data indicating no warning signs, may display information on its display unit indicating that no signs of a break in the transmission line 5 have occurred, or it may transmit the data indicating no warning signs to an external device. The external device, upon receiving the data indicating no warning signs, may display information indicating that no signs of a break in the transmission line 5 have occurred.

[0162] As can be seen from the frequency characteristics shown in Figures 9, 11, and 12 above, the absolute value of the difference between the signal strength of the detection received signal and the reference minimum peak signal strength (corresponding to the absolute value of the difference Δ1) tends to increase as the transmission frequency increases. Therefore, as in the example above, by changing the transmission frequency so that it gradually decreases from 975 MHz during the detection process, the time from the start of the detection process to the determination of YES in step s64 when a break in the transmission line 5 is detected can be shortened. Thus, the time required for the detection process when a break in the transmission line 5 is detected can be shortened.

[0163] In addition, the second processing unit 2 may, in the second detection process, detect signs of a break in the transmission line 5 based on a detection receiving signal corresponding to a detection transmission signal transmitted by the first processing unit 1 at multiple frequencies. In this case, the M transmission frequencies of the detection transmission signals that the first processing unit 1 can transmit can be divided into, for example, a high-frequency group, a medium-frequency group, and a low-frequency group.

[0164] The high-frequency group consists of six frequencies F3, for example, when parameter N is between 14 and 19. The maximum and minimum frequencies in the high-frequency group are 975 MHz and 725 MHz, respectively. The mid-frequency group consists of six frequencies F3, for example, when parameter N is between 8 and 13. The maximum and minimum frequencies in the mid-frequency group are 675 MHz and 425 MHz, respectively. The low-frequency group consists of six frequencies F3, for example, when parameter N is between 2 and 7. The maximum and minimum frequencies in the low-frequency group are 375 MHz and 125 MHz, respectively. If we represent the number of frequencies constituting each of the high-frequency, mid-frequency, and low-frequency groups as X, then for example, X = 6.

[0165] When the detection process starts, the first processing unit 1 transmits detection transmission signals at X frequencies (six in this example) that constitute a high-frequency group. That is, the first processing unit 1 transmits detection transmission signals X times by sequentially changing the transmission frequency among the X frequencies that constitute the high-frequency group. In step s61, the second processing unit 2 receives detection transmission signals at the high-frequency group frequencies X times. Next, in step s62, the processing unit 20 acquires the signal strength of each of the X received detection signals.

[0166] In the second detection process of step s63, the processing unit 20 obtains the absolute value of the difference between the signal strength of each of the X detection received signals and the above-mentioned minimum reference peak signal strength. The processing unit 20 then obtains the sum of the absolute values ​​of the X obtained differences as the second determination value. When the second determination value is greater than or equal to the threshold, the processing unit 20 determines that it has detected an indication of a break in the transmission line 5 in the second detection process. On the other hand, when the second determination value is less than the threshold, the processing unit 20 determines that it did not detect an indication of a break in the transmission line 5 in the second detection process. Thereafter, the second processing unit 2 operates in the same manner as described above. Subsequently, for example, when step s67 is executed, the first processing unit 1, which has received the transmission instruction data, transmits detection transmission signals at X frequencies that constitute the mid-range group, for example. In step s61, the second processing unit 2 receives detection transmission signals at the frequencies of the mid-range group X times. Thereafter, the second processing unit 2 operates similarly, and for example, when step s67 is executed, the first processing unit 1, having received the transmission instruction data, transmits detection transmission signals at X frequencies that constitute a low-frequency group. In step s61, the second processing unit 2 receives detection transmission signals at the low-frequency group frequencies X times. Thereafter, the second processing unit 2 operates similarly, and for example, if it is determined to be NO in step s64, it is determined to be YES in step s66. Then, step s68 is executed.

[0167] In the example above, the M transmission frequencies are divided into three groups, but they may also be divided into two groups, or into four or more groups. The value of X is not limited to the example above.

[0168] In the detection process described above, the first processing unit 1 sets the transmission frequency to frequency F3, but it may also set it to a value other than frequency F3. For example, the first processing unit 1 may change the transmission frequency from 100 MHz to 1 GHz in increments of 1 MHz, or in increments of 10 MHz, or in increments of 100 MHz. The value of M is not limited to the above example.

[0169] If the transmission frequency is set to a frequency other than F3, the storage unit 21 of the second processing unit 2 stores frequency characteristic data (hereinafter also referred to as the reference frequency characteristic) of the signal strength of the detection received signal when the transmission frequency changes from 1 Hz to 1 GHz, for example, when there is an impedance mismatch and the transmission line 5 is normal. The reference frequency characteristic is an actual measured value. The reference frequency characteristic is the same as the mismatch and normal frequency characteristics shown in Figure 7 above. Hereafter, the signal strength of the detection received signal shown by the reference frequency characteristic will be called the reference signal strength.

[0170] In the first detection process performed in step s42 of Figure 14 above, the processing unit 20 obtains a reference signal strength corresponding to each of the signal strengths of the detection received signals acquired M times from the frequency characteristic data in the storage unit 21. The reference signal strength corresponding to the signal strength of the mth detection received signal is the reference signal strength at the same frequency as the frequency of the mth detection received signal (i.e., the transmission frequency of the mth) in the reference frequency characteristics. For example, if the transmission frequency of the mth is 500 MHz, the reference signal strength corresponding to the signal strength of the mth detection received signal is the reference signal strength at 500 MHz in the reference frequency characteristics.

[0171] Next, the processing unit 20 obtains the absolute value of the difference between each of the M received detection signals and the corresponding reference signal. Then, the processing unit 20 obtains the sum of the absolute values ​​of the M obtained differences as the first determination value.

[0172] In step s61 of Figure 21 above, when the second processing unit 2 receives the detection transmission signal X times, in the second detection process in step s63, the processing unit 20 obtains six reference signal strengths from the frequency characteristic data in the storage unit 21, corresponding to the signal strengths of the X detection received signals obtained in step s62. Then, for each of the X detection received signal strengths, the processing unit 20 obtains the absolute value of the difference between that signal strength and its corresponding reference signal strength. The processing unit 20 uses the sum of the absolute values ​​of the X obtained differences as the second determination value.

[0173] In the detection process, the detection unit 29 may detect the state of the transmission line 5 based on the waveform of the frequency characteristics of the signal strength of the detection receiving signal when the transmission frequency changes. Figure 22 is a flowchart showing an example of the operation of the processing system 3 in this case.

[0174] In this example, in step s71, the first processing unit 1 transmits a detection transmission signal 109 times, for example, by changing the transmission frequency from 1 Hz to 1 GHz in 1 Hz increments. In this case, M = 109. In the second processing unit 2, which has received the detection transmission signal 109 times, in step s81, the processing unit 20 acquires the frequency characteristics (also called detection frequency characteristics) of the signal strength of the detection received signal when the transmission frequency changes from 1 Hz to 1 GHz in 1 Hz increments. In step s81, the processing unit 20 acquires the signal strength of each of the 109 detection received signals in the same manner as in step s41, and acquires the detection frequency characteristics. The detection frequency characteristics show, for example, the signal strength of the detection received signal at 1 Hz intervals in the range of the frequency of the detection received signal from 1 Hz to 1 GHz.

[0175] If there are no signs of breakage in transmission line 5, the detection frequency characteristics will be the same as the mismatch / normal frequency characteristics shown in Figure 7 above. On the other hand, if there are signs of breakage in transmission line 5, the detection frequency characteristics will be the same as the mismatch / breakage warning frequency characteristics shown in Figures 9, 11, and 12 above.

[0176] Next, in step s82, the processing unit 20 performs a third detection process to detect signs of a break in the transmission line 5 based on the waveform of the detection frequency characteristic acquired in step s81. In the third detection process, the processing unit 20 virtually replaces frequency with time in the detection frequency characteristic, and considers the detection frequency characteristic as a virtual time characteristic of the signal intensity of the detection received signal. Hereafter, this virtual time characteristic will be called the virtual detection time characteristic. The processing unit 20 virtually treats the signal intensity of the detection received signal at each frequency as the signal intensity of the detection received signal at each time.

[0177] Figure 23 is a graph showing an example of the virtual detection time characteristics. The horizontal axis of Figure 23 represents time, and the vertical axis of Figure 23 represents the signal strength of the detection received signal at the time indicated on the horizontal axis. In Figure 23, an example of the virtual detection time characteristics when there are no signs of breakage in the transmission line 5 is shown by a relatively thin line. Also in Figure 23, an example of the virtual detection time characteristics when a breakage indication location 150 as shown in Figure 8 occurs in the transmission line 5 is shown by a relatively thick line.

[0178] The processing unit 20 virtually replaces, for example, the unit 1 Hz in the detection frequency characteristics with the unit 10⁻¹² seconds. In this case, the signal strength at 1 MHz in the detection frequency characteristics becomes the signal strength of 10⁻⁶ seconds in the virtual detection time characteristics, and the signal strength at 10 MHz in the detection frequency characteristics becomes the signal strength of 10⁻⁵ seconds in the virtual detection time characteristics. Also, the signal strength at 100 MHz in the detection frequency characteristics becomes the signal strength of 10⁻⁴ seconds in the virtual detection time characteristics, and the signal strength at 1 GHz in the detection frequency characteristics becomes the signal strength of 10⁻³ seconds in the virtual detection time characteristics. Furthermore, the interval of 50 MHz in the detection frequency characteristics becomes the interval of 50 × 10⁻⁶ seconds in the virtual detection time characteristics. The waveform of the detection frequency characteristics is viewed virtually as a time waveform, which becomes the waveform of the virtual detection time characteristics. Hereafter, the time signal representing the virtual detection time characteristics may be called the virtual detection time signal.

[0179] When there are no signs of breakage in transmission line 5, the waveform of the detection frequency characteristic is a sine wave with a period of 50 MHz (see Figure 7). Therefore, when there are no signs of breakage in transmission line 5, the waveform of the virtual detection time characteristic is a sine wave with a period of 50 × 10⁻⁶ seconds (see the thin line graph in Figure 23). In other words, when there are no signs of breakage in transmission line 5, the waveform of the virtual detection time characteristic is a sine wave with a frequency of 20 kHz.

[0180] On the other hand, if a breakage is imminent in the transmission line 5, as described above, various reflections occur in the transmission line 5 regarding the reflection of the detection transmission signal, in addition to the reflection between one end 5a and the other end 5b. Therefore, the waveform of the detection frequency characteristic will not be a sine wave (see Figures 9, 11, and 12). Consequently, when there is a breakage imminent in the transmission line 5, the waveform of the virtual detection time characteristic (in other words, the waveform of the virtual detection time signal) will not be a sine wave (see the thick line graph in Figure 23), but will include frequency components other than the 20 kHz frequency component.

[0181] Therefore, the processing unit 20 performs a Fourier transform on the virtual detection time characteristic, or in other words, performs a Fourier transform on the virtual detection time signal, to obtain the frequency spectrum of the virtual detection time signal (or in other words, the frequency spectrum of the waveform of the virtual detection time characteristic). The processing unit 20 then determines that there is no indication of a break in the transmission line 5 if the obtained frequency spectrum does not contain any frequency components other than the 20 kHz frequency component. On the other hand, the processing unit 20 determines that there is an indication of a break in the transmission line 5 if the obtained frequency spectrum contains frequency components other than the 20 kHz frequency component. The frequency spectrum of the virtual detection time signal can also be said to be the frequency spectrum of the time waveform when the waveform of the detection frequency characteristic is viewed virtually as a time waveform.

[0182] After the third detection process in step s82, in step s83, the second processing unit 2 transmits detection result data indicating the detection result of the transmission line 5 breakage precursor (in this case, the result of the third detection process) to the first processing unit 1. This completes the detection process.

[0183] In the detection process, the detection unit 29 may determine the likelihood of a break in the transmission line 5. The likelihood of a break can also be described as the degree to which a break is likely to occur in the transmission line 5. The higher the likelihood of a break in the transmission line 5, the more likely a break is to occur in the transmission line 5. The likelihood of a break can also be described as the severity of the break. For example, in the first detection process of step s42 described above, the processing unit 20 may determine the likelihood of a break based on the first determination value.

[0184] Here, the larger the impedance of the breakage indication point 150 in the transmission line 5, the higher the degree of breakage indication at the breakage indication point 150. For example, if the transmission line 5 is a stranded cable, the larger the number of strands that are broken at the breakage indication point 150 in the transmission line 5, the larger the impedance of the breakage indication point 150, and the higher the degree of breakage indication at the breakage indication point 150. Furthermore, the larger the impedance of the breakage indication point 150, the greater the difference between the waveform during mismatch / breakage indication (the thick line waveform in Figures 9, 11, and 12) and the waveform during mismatch / normal operation (the thin line waveform in Figures 9, 11, and 12).

[0185] If the degree of impending breakage is determined in the first detection process, the processing unit 20 determines that no impending breakage has occurred in the transmission line 5 if the first determination value, which is the sum of the absolute values ​​of M differences, is less than the first threshold. On the other hand, if the first determination value is equal to or greater than the first threshold, the processing unit 20 determines that an impending breakage has occurred in the transmission line 5 and determines the degree of impending breakage in the transmission line 5.

[0186] Here, assuming that the transmission line 5 is a stranded cable composed of, for example, seven strands, the breakage prediction level when one strand is broken is defined as the first level, and the breakage prediction level when two strands are broken is defined as the second level. Furthermore, the breakage prediction level when three strands are broken is defined as the third level, and the breakage prediction level when four strands are broken is defined as the fourth level. Then, the breakage prediction level when five strands are broken is defined as the fifth level, and the breakage prediction level when six strands are broken is defined as the sixth level. The higher the breakage prediction level, the higher the breakage prediction level and the more likely the transmission line 5 is to break. By determining the breakage prediction level, the processing unit 20 can determine the number of strands that are broken in the stranded cable.

[0187] The processing unit 20 determines that the likelihood of a break in the transmission line 5 is at the first level if the first determination value is greater than or equal to the first threshold and less than the second threshold. The second threshold is a value greater than the first threshold. It can also be said that the processing unit 20 determines that one strand of wire is broken in the stranded cable if the first determination value is greater than or equal to the first threshold and less than the second threshold.

[0188] The processing unit 20 determines that the likelihood of a break in the transmission line 5 is at level 2 if the first determination value is greater than or equal to the second threshold and less than the third threshold. The third threshold is a value greater than the second threshold.

[0189] The processing unit 20 determines that the likelihood of a break in the transmission line 5 is at level 3 if the first determination value is greater than or equal to the third threshold and less than the fourth threshold. The fourth threshold is a value greater than the third threshold.

[0190] The processing unit 20 determines that the likelihood of a break in the transmission line 5 is at level 4 if the first determination value is greater than or equal to the fourth threshold and less than the fifth threshold. The fifth threshold is a value greater than the fourth threshold.

[0191] The processing unit 20 determines that the likelihood of a break in the transmission line 5 is at level 5 if the first determination value is greater than or equal to the fifth threshold and less than the sixth threshold. The sixth threshold is a value greater than the fifth threshold.

[0192] The processing unit 20 determines that the likelihood of a break in the transmission line 5 is at level 6 if the first determination value is greater than or equal to the sixth threshold and less than the seventh threshold. The seventh threshold is a value greater than the sixth threshold.

[0193] In this way, the processing unit 20 can determine the likelihood of a wire break by, for example, comparing a first determination value with a plurality of threshold values.

[0194] If the detection unit 29 determines in the second detection process in Figure 21 that there is a sign of a break in the transmission line 5, it may determine the degree of breakage in the transmission line 5. For example, consider the case in the example of Figure 21 where, as described above, M transmission frequencies are divided into high-frequency group, mid-frequency group, and low-frequency group. In this case, the processing unit 20 may determine the degree of breakage by comparing a second determination value, which is the sum of the absolute values ​​of X differences, with a plurality of threshold values, similar to the case where the degree of breakage is determined by comparing a first determination value with a plurality of threshold values.

[0195] Furthermore, if the detection unit 29 determines in the third detection process shown in Figure 22 that a breakage is imminent in the transmission line 5, it may determine the degree of breakage in the transmission line 5 based on the detection frequency characteristics acquired in step s81. In this case, the memory unit 21 stores frequency characteristic data showing the above-mentioned reference frequency characteristics. The processing unit 20 then obtains the reference signal strength corresponding to the signal strength at each frequency in the detection frequency characteristics acquired in step s81 from the frequency characteristic data in the memory unit 21. Next, the processing unit 20 obtains the sum of the absolute values ​​of the differences between the signal strength at each frequency in the detection frequency characteristics and the corresponding reference signal strength as the third determination value. The processing unit 20 then determines the degree of breakage by comparing the third determination value with a plurality of thresholds, in the same manner as when the degree of breakage is determined by comparing the first determination value with a plurality of thresholds.

[0196] The second processing unit 2 may transmit wire breakage prediction data indicating the determined wire breakage prediction degree to the first processing unit 1. The first processing unit 1, upon receiving the wire breakage prediction data, may display the wire breakage prediction degree indicated by the wire breakage prediction data on a display unit, or it may transmit the wire breakage prediction data to an external device. The external device, upon receiving the wire breakage prediction data, may display the wire breakage prediction degree indicated by the wire breakage prediction data.

[0197] In the examples shown in Figures 8 and 10 above, only one potential disconnection point 150 occurs in the transmission line 5. However, even if multiple potential disconnection points 150 occur in the transmission line 5, the detection unit 29 can detect the potential disconnection of the transmission line 5 in the same manner as described above.

[0198] Figure 24 is a graph showing an example of the frequency characteristics during mismatch / predicted disconnection when there are two pre-disconnection points 150 in the transmission line 5, at 1m and 2m from one end 5a. Figure 25 is a graph showing an example of the frequency characteristics during mismatch / predicted disconnection when there are two pre-disconnection points 150 in the transmission line 5, at 0.7m and 1.8m from one end 5a. In Figures 24 and 25, as with Figure 8, the frequency characteristics during mismatch / predicted disconnection are shown by relatively thick lines, and the frequency characteristics during mismatch / normal operation are shown by relatively thin lines.

[0199] As shown in Figures 24 and 25, if a breakage warning point 150 occurs at two locations in the transmission line 5, the waveform during mismatch / breakage warning (thick line waveform) will differ from the waveform during mismatch / normal operation (thin line waveform), similar to the case where a breakage warning point 150 occurs at one location in the transmission line 5. Therefore, the detection unit 29 can detect a breakage warning in the transmission line 5 in the same manner as described above.

[0200] In the detection process described above, both the output impedance Z1 and the input impedance Z2 differed from the transmission line impedance. However, it is also possible for only one of the output impedance Z1 or input impedance Z2 to differ from the transmission line impedance. Even in this case, the detection unit 29 can detect signs of a break in the transmission line 5 based on the detection received signal.

[0201] Figures 26 and 27 schematically show an example of a transmission system 4 including a detection mode processing system 3. In the examples of Figures 26 and 27, the output impedance Z1 (100 Ω in this example) is different from the transmission line impedance, but the input impedance Z2 matches the transmission line impedance. Also, in the example of Figure 26, no breakage indicator point 150 has occurred in the transmission line 5. Also, in the example of Figure 27, a breakage indicator point 150 has occurred in the center of the transmission line 5, similar to the example of Figure 8. Hereafter, the state in which only the output impedance Z1 differs from the transmission line impedance among the output impedance Z1 and input impedance Z2 will be referred to as the second impedance mismatch state.

[0202] Figure 28 is a graph showing an example of the simulation results of the S21 frequency characteristics of the detection transmission signal in the transmission line 5 in the examples of Figures 26 and 27. In Figure 28, the S21 frequency characteristics in the example of Figure 26 are shown by a relatively thin line, and the S21 frequency characteristics in the example of Figure 27 are shown by a relatively thick line. Hereafter, the S21 frequency characteristics when no signs of breakage occur in the transmission line 5 under the second impedance mismatch state may be referred to as the second mismatch / normal frequency characteristics. The waveform of the second mismatch / normal frequency characteristics may also be referred to as the second mismatch / normal waveform. Furthermore, the S21 frequency characteristics when signs of breakage occur in the transmission line 5 under the second impedance mismatch state may be referred to as the second mismatch / breakage warning frequency characteristics. Furthermore, the waveform of the second mismatch / breakage warning frequency characteristics may also be referred to as the second mismatch / breakage warning waveform.

[0203] As shown by the thin line in Figure 28, the second mismatch / normal waveform is a straight line. In contrast, as shown by the thick line in Figure 28, the second mismatch / break precursor waveform is a waveform in which a maximum or minimum peak appears at frequencies corresponding to the distance between one end 5a of the transmission line 5 (in other words, the mismatched end) and the break precursor location 150. The frequency corresponding to the distance between one end 5a of the transmission line 5 and the break precursor location 150 is the reciprocal of the time it takes for the detection transmission signal to make one round trip between one end 5a of the transmission line 5 and the break precursor location 150. In the example in Figure 27, the distance between one end 5a of the transmission line 5 and the break precursor location 150 is 1.5 m, so the frequency corresponding to the distance between one end 5a of the transmission line 5 and the break precursor location 150 is 100 MHz. The second mismatch / break precursor waveform shown by the thick line in Figure 28 is a waveform in which a maximum or minimum peak appears at 100 MHz intervals. Furthermore, in the second waveform indicating mismatch / disconnection, similar to the waveforms indicating mismatch / disconnection shown in Figure 9, the minimum peak changes in a manner similar to the change in a cosine wave with a period of 15 GHz corresponding to the length d of the disconnection location 150.

[0204] Even if only the input impedance Z2 differs from the transmission line impedance among the output impedance Z1 and input impedance Z2, the waveform of the S21 frequency response will be a straight line when the transmission line 5 is functioning normally. Furthermore, when there is a sign of a break in the transmission line 5, the waveform of the S21 frequency response will be a waveform in which a maximum or minimum peak appears at each frequency corresponding to the distance between the other end 5b of the transmission line 5 (in other words, one end on the mismatched side) and the break warning location 150. The frequency corresponding to the distance between the other end 5b of the transmission line 5 and the break warning location 150 is the reciprocal of the time it takes for the detection transmission signal to make one round trip between the break warning location 150 and the other end 5b of the transmission line 5. In the waveform of the S21 frequency response when there is a sign of a break in the transmission line 5, the minimum peak changes in a manner similar to the change of a cosine wave with a period of 15 GHz corresponding to the length d of the break warning location 150.

[0205] In the detection process, if only one of the output impedance Z1 or input impedance Z2 differs from the transmission line impedance, the first processing unit 1 transmits a detection transmission signal 109 times, for example, by changing the transmission frequency from 1 Hz to 1 GHz in 1 Hz increments. In this case, M = 109. The second processing unit 2, having received the detection transmission signal 109 times, for example in the first detection process of step s42, the processing unit 20 acquires the signal strength of each of the 109 received detection signals. Next, the processing unit 20 acquires the absolute value of the difference between the signal strength and the corresponding reference signal strength for each of the 109 received detection signals. Next, the processing unit 20 acquires the sum of the absolute values ​​of the 109 acquired differences as the first determination value. Then, the processing unit 20 detects an indication of a break in the transmission line 5 based on the acquired first determination value in the same manner as above.

[0206] Furthermore, in the detection process, if only one of the output impedance Z1 or input impedance Z2 differs from the transmission line impedance, and in the example of Figure 21, when the M transmission frequencies are divided into multiple groups (for example, a high-frequency group, a mid-frequency group, and a low-frequency group) as described above, the processing unit 20 can detect signs of a break in the transmission line 5 by executing the second detection process in the same manner as described above.

[0207] Furthermore, in the detection process, if only one of the output impedance Z1 or input impedance Z2 differs from the transmission line impedance, in the example of Figure 22, the processing unit 20 determines in the third detection process that there is no indication of a break in the transmission line 5 if the acquired frequency spectrum does not contain any frequency components other than the 0 Hz frequency component. On the other hand, the processing unit 20 determines that there is an indication of a break in the transmission line 5 if the acquired frequency spectrum contains frequency components other than the 0 Hz frequency component.

[0208] In the detection process, the output impedance Z1 and input impedance Z2 may each match the transmission line impedance. In the matching / disconnection prediction waveform, as shown in Figure 5, if the frequency of the single-frequency transmission signal is a relatively high frequency, for example, in the range of 4 GHz to 11 GHz, the effects of the disconnection prediction are more likely to appear in the single-frequency transmission signal. When the output impedance Z1 and input impedance Z2 each match the transmission line impedance, the first processing unit 1 transmits a detection transmission signal, for example, with a transmission frequency set to a range of 4 GHz or higher and 11 GHz or lower. The Nyquist frequency of the AD converter 26 of the second processing unit 2 is set to a value sufficiently lower than the range of 4 GHz to 11 GHz, for example, 1 GHz. The processing unit 20 then acquires the signal strength of the alias component having a frequency below the Nyquist frequency included in the AD output signal as the signal strength of the detection reception signal. The processing unit 20 then determines that a disconnection prediction has occurred in the transmission line 5 when the acquired signal strength of the detection reception signal is above a threshold. On the other hand, the processing unit 20 determines that there is no indication of a break in the transmission line 5 when the signal strength of the acquired detection received signal is below a threshold.

[0209] In the detection process, even if the output impedance Z1 and input impedance Z2 each match the transmission line impedance, the processing unit 20 may still determine the degree of impending breakage in the transmission line 5. When the output impedance Z1 and input impedance Z2 each match the transmission line impedance, the minimum peak of the matching / predicted breakage waveform increases in the negative direction as the degree of impending breakage in the transmission line 5 increases, or in other words, as the impedance of the impending breakage location 150 increases. The processing unit 20 may determine that an impending breakage has occurred in the transmission line 5 when the signal strength of the acquired detection received signal is above a threshold, and then determine the degree of impending breakage. For example, the processing unit 20 may determine the degree of impending breakage by comparing the signal strength of the detection received signal with multiple thresholds, similar to when the degree of impending breakage is determined by comparing a first determination value with multiple thresholds.

[0210] Thus, in the detection process, even when the output impedance Z1 and input impedance Z2 each match the transmission line impedance, the signal strength of the alias component with a frequency below the Nyquist frequency included in the AD output signal is acquired as the signal strength of the detection received signal. This allows the AD converter 26, whose Nyquist frequency is lower than the transmission frequency, to correctly acquire the signal strength of the detection received signal.

[0211] In the above example, the first processing unit 1 transmits a detection transmission signal during the detection process. However, the second processing unit 2 may transmit a second single-frequency transmission signal for detection, and the first processing unit 1 may detect the state of the transmission line 5 based on the received second transmission signal.

[0212] Furthermore, in the above example, the processing system 3 is equipped with a data communication mode, but it does not necessarily have to be equipped with a data communication mode. In this case, the processing system 3 may be a dedicated system for detecting the state of the transmission line 5.

[0213] The functions of the elements disclosed herein may be implemented using general-purpose processors, dedicated processors, integrated circuits, ASICs ("Application-Specific Integrated Circuits"), conventional circuit configurations and / or combinations thereof, or processing circuit configurations, which are configured to perform the disclosed elements or programmed to perform the disclosed functions. A processor is considered a processing circuit configuration or circuit configuration if it includes transistors and other circuit configurations within it. In this disclosure, a circuit configuration, unit or means is hardware that performs the listed functions or hardware programmed to perform such functions. Hardware may be any hardware disclosed herein or other known hardware programmed to perform the listed functions or configured to perform such functions. When hardware is a processor that may be considered a type of circuit configuration, a circuit configuration, means or unit is a combination of hardware and software, software used to configure the hardware and / or processor.

[0214] As described above, the processing system has been explained in detail, but the above description is illustrative in all respects, and the invention is not limited thereto. Furthermore, the various examples described above can be combined and applied insofar as they do not contradict each other. And it is understood that countless examples not illustrated can be conceived without falling outside the scope of this disclosure.

[0215] This disclosure includes the following aspects:

[0216] A processing system according to the first embodiment comprises a first processing unit that transmits a transmission signal and a second processing unit that receives the transmission signal transmitted by a wired transmission line, wherein at least one of the output impedance of the first processing unit and the input impedance of the second processing unit is different from the characteristic impedance of the transmission line, and the second processing unit has a detection unit that detects the state of the transmission line based on the received signal, which is the transmission signal received by the second processing unit.

[0217] The processing system according to the second embodiment is the processing system according to the first embodiment, wherein the output impedance and the input impedance are each different from the characteristic impedance.

[0218] The processing system according to the third embodiment is a processing system according to the first embodiment or the second embodiment, wherein the first processing device transmits the transmission signal having a first transmission frequency based on the length of the transmission line.

[0219] A processing system according to a fourth embodiment is a processing system according to a third embodiment, wherein the first processing device sets the first transmission frequency to a frequency equal to or greater than the reciprocal of the time it takes for the transmission signal to travel along the transmission path for a given length.

[0220] The processing system according to the fifth embodiment is a processing system according to the third or fourth embodiment, wherein the first processing unit obtains the time from when a signal is transmitted until the signal is reflected back by the second processing unit, obtains the length of the transmission line based on the obtained time, and sets the first transmission frequency based on the length.

[0221] The processing system according to the sixth embodiment is a processing system according to any one of the first to fifth embodiments, wherein the first processing device changes the transmission frequency of the transmission signal, and the detection unit detects the state of the transmission line based on the received signal corresponding to a plurality of values ​​of the transmission frequency.

[0222] The processing system according to the seventh embodiment is the processing system according to the sixth embodiment, wherein the detection unit detects the state of the transmission line based on the waveform of the frequency characteristics of the signal strength of the received signal when the transmission frequency changes.

[0223] The processing system according to the eighth embodiment is a processing system according to any one of the first to seventh embodiments, wherein the first processing unit transmits the transmission signal at at least one frequency, the detection unit performs a first process to detect the state of the transmission line based on the received signal corresponding to the transmission signal transmitted at at least one frequency, and if the state of the transmission line is not detected in the first process, the first processing unit retransmits the transmission signal at at least one frequency different from the previous time, and the detection unit performs a second process to detect the state of the transmission line based on the received signal corresponding to the retransmitted transmission signal.

[0224] The processing system according to the ninth embodiment is a processing system according to any one of the first to eighth embodiments, wherein the detection unit has an AD converter that converts the received signal from analog format to digital format, and detects the state of the transmission line based on the output signal of the AD converter.

[0225] The processing system according to the tenth embodiment is a processing system according to the ninth embodiment, wherein the first processing unit transmits a transmission signal having a first transmission frequency greater than the Nyquist frequency of the AD converter, and the detection unit acquires, based on the output signal, the first signal intensity of an alias component having an alias frequency less than or equal to the Nyquist frequency, which is included in the output signal corresponding to the transmission signal having the first transmission frequency, and detects the state of the transmission line based on the acquired first signal intensity.

[0226] The processing system according to the eleventh embodiment is the processing system according to the tenth embodiment, wherein the first processing unit notifies the second processing unit of the first transmission frequency or the alias frequency.

[0227] The processing system according to the twelfth embodiment is the processing system according to the tenth embodiment, wherein the second processing unit has prior knowledge of the first transmission frequency or the alias frequency.

[0228] The processing system according to the 13th embodiment is a processing system according to any one of the 10th to 12th embodiments, wherein the first processing device changes the transmission frequency of the transmission signal, the detection unit detects the state of the transmission line based on the signal strength of the received signal corresponding to a plurality of values ​​of the transmission frequency, acquires the first signal strength of the alias component as the signal strength of the received signal corresponding to the transmission signal having the first transmission frequency, and acquires the second signal strength of a frequency component having the same frequency as the second transmission frequency included in the output signal as the signal strength of the received signal corresponding to the transmission signal having a second transmission frequency less than or equal to the Nyquist frequency.

[0229] The processing system according to the 14th embodiment is a processing system according to any one of the 9th to 13th embodiments, wherein the detection unit acquires the signal strength of the received signal based on the output signal, performs a correction process on the acquired signal strength to correct for attenuation due to the aperture effect, and detects the state of the transmission line based on the signal strength after the correction process.

[0230] A processing system according to the 15th embodiment is a processing system according to any one of the first to 14th embodiments, the processing system comprising a detection mode in which the first processing unit transmits the transmission signal and the second processing unit detects the state of the transmission line based on the reception signal, and a data communication mode in which the first processing unit and the second processing unit communicate data through the transmission line.

[0231] The processing system according to the 16th embodiment is the processing system described in any one of the first to 15 embodiments, wherein the detection unit detects an indication of a break in the transmission line based on the received signal.

[0232] The processing system according to the 17th embodiment is the processing system according to the 16th embodiment, wherein the first processing unit changes the transmission frequency of the transmission signal, and the detection unit determines the likelihood of a break in the transmission line based on the signal strength of the received signal corresponding to a plurality of values ​​of the transmission frequency.

[0233] The second processing device according to the 18th embodiment is a second processing device provided in a processing system according to any one of the first to 17th embodiments.

[0234] The first processing device according to the 19th embodiment is a first processing device provided in any one of the processing systems according to the first to 17th embodiments.

[0235] The program according to the 20th aspect is a program for causing a computer device to function as a second processing unit according to the 18th aspect.

[0236] The program according to the 21st aspect is a program for causing a computer device to function as a first processing unit according to the 19th aspect.

[0237] The detection method according to the 22nd embodiment involves a first processing unit transmitting a transmission signal, a second processing unit receiving the transmission signal transmitted by a wired transmission line, at least one of the output impedance of the first processing unit and the input impedance of the second processing unit being different from the characteristic impedance of the transmission line, and the second processing unit detecting the state of the transmission line based on the received signal, which is the transmission signal received by the second processing unit.

[0238] 1 First processing unit 2 Second processing unit 3 Processing system 5 Transmission line 26 AD converter 29 Detection unit Z1 Output impedance Z2 Input impedance

Claims

1. A processing system comprising a first processing unit that transmits a transmission signal, and a second processing unit that receives the transmission signal transmitted by a wired transmission line, wherein at least one of the output impedance of the first processing unit and the input impedance of the second processing unit is different from the characteristic impedance of the transmission line, and the second processing unit has a detection unit that detects the state of the transmission line based on the received signal, which is the transmission signal received by the second processing unit.

2. A processing system according to claim 1, wherein the output impedance and the input impedance are each different from the characteristic impedance.

3. A processing system according to claim 1, wherein the first processing device transmits the transmission signal having a first transmission frequency based on the length of the transmission path.

4. The processing system according to claim 3, wherein the first processing device sets the first transmission frequency to a frequency equal to or greater than the reciprocal of the first time it takes for the transmission signal to travel along the transmission path by the length of the path.

5. A processing system according to claim 3, wherein the first processing unit acquires a second time from the time a signal is transmitted until the signal is reflected back by the second processing unit, acquires the length of the transmission line based on the acquired second time, and sets a first transmission frequency based on the length.

6. A processing system according to claim 1, wherein the first processing device changes the transmission frequency of the transmission signal, and the detection unit detects the state of the transmission line based on the received signal corresponding to a plurality of values ​​of the transmission frequency.

7. A processing system according to claim 6, wherein the detection unit detects the state of the transmission line based on the waveform of the frequency characteristics of the signal intensity of the received signal when the transmission frequency changes.

8. A processing system according to claim 1, wherein the first processing unit transmits the transmission signal at at least one frequency, the detection unit performs a first process to detect the state of the transmission line based on the received signal corresponding to the transmission signal transmitted at at least one frequency, and if the state of the transmission line is not detected in the first process, the first processing unit retransmits the transmission signal at at least one frequency different from the previous time, and the detection unit performs a second process to detect the state of the transmission line based on the received signal corresponding to the retransmitted transmission signal.

9. A processing system according to claim 1, wherein the detection unit has an AD converter that converts the received signal from analog format to digital format, and the processing system detects the state of the transmission line based on the output signal of the AD converter.

10. A processing system according to claim 9, wherein the first processing device transmits a transmission signal having a first transmission frequency greater than the Nyquist frequency of the AD converter, and the detection unit acquires, based on the output signal, the first signal intensity of an alias component having an alias frequency less than or equal to the Nyquist frequency, which is included in the output signal corresponding to the transmission signal having the first transmission frequency, and detects the state of the transmission line based on the acquired first signal intensity.

11. A processing system according to claim 10, wherein the first processing unit notifies the second processing unit of the first transmission frequency or the alias frequency.

12. The processing system according to claim 10, wherein the second processing device has prior knowledge of the first transmission frequency or the alias frequency.

13. A processing system according to claim 10, wherein the first processing device changes the transmission frequency of the transmission signal, the detection unit detects the state of the transmission line based on the signal strength of the received signal corresponding to a plurality of values ​​of the transmission frequency, acquires the first signal strength of the alias component as the signal strength of the received signal corresponding to the transmission signal having the first transmission frequency, and acquires the second signal strength of a frequency component included in the output signal having the same frequency as the second transmission frequency as the signal strength of the received signal corresponding to the transmission signal having a second transmission frequency less than or equal to the Nyquist frequency.

14. A processing system according to claim 9, wherein the detection unit acquires the signal strength of the received signal based on the output signal, performs a correction process on the acquired signal strength to correct for attenuation due to the aperture effect, and detects the state of the transmission line based on the signal strength after the correction process.

15. A processing system according to claim 1, wherein the processing system comprises a detection mode in which the first processing unit transmits the transmission signal and the second processing unit detects the state of the transmission line based on the reception signal, and a data communication mode in which the first processing unit and the second processing unit communicate data through the transmission line.

16. A processing system according to claim 1, wherein the detection unit detects an indication of a break in the transmission line based on the received signal.

17. A processing system according to claim 16, wherein the first processing device changes the transmission frequency of the transmission signal, and the detection unit determines the likelihood of a break in the transmission line based on the signal strength of the received signal corresponding to a plurality of values ​​of the transmission frequency.

18. A second processing apparatus comprising the processing system according to any one of claims 1 to 17.

19. A first processing apparatus comprising the processing system according to any one of claims 1 to 17.

20. A program for causing a computer device to function as the second processing unit described in claim 18.

21. A program for causing a computer device to function as the first processing unit described in claim 19.

22. A detection method comprising: a first processing unit transmitting a transmission signal; a second processing unit receiving the transmission signal transmitted by a wired transmission line; at least one of the output impedance of the first processing unit and the input impedance of the second processing unit being different from the characteristic impedance of the transmission line; and the second processing unit detecting the state of the transmission line based on the received signal, which is the transmission signal received by the second processing unit.

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