Transmission path length detection device and network communication device

Abstract

The transmission path length detection device (3) is configured to include: a first electrostatic capacitance calculation unit (21) which observes the voltage change of the transmission path (2) in the communication network and calculates the overall electrostatic capacitance of the transmission path (2), i.e., the total electrostatic capacitance, based on the voltage change; a second electrostatic capacitance calculation unit (22) which measures the characteristic impedance of the transmission path (2) and calculates the electrostatic capacitance per unit length of the transmission path (2) based on the characteristic impedance; and an electrical length calculation unit (23) which divides the total electrostatic capacitance calculated by the first electrostatic capacitance calculation unit (21) by the electrostatic capacitance per unit length calculated by the second electrostatic capacitance calculation unit (22) to thereby calculate the electrical length of the transmission path (2).

Description

Technical Field

[0001] The present disclosure relates to a transmission path length detection device for calculating the electrical length of a transmission path, and a network communication device including the transmission path length detection device. Background Art

[0002] As a communication network used by a network communication device in sending and receiving signals, an existing communication network is sometimes used. The transmission speed of the signal sent and received by the network communication device is sometimes determined to be a transmission speed within a range in which the communication network can be treated as a lumped constant line. In order to determine the transmission speed, it is necessary to measure the electrical length of the transmission path.

[0003] As a method for measuring the electrical length of a transmission path, the TDR (Time Domain Reflectometry) method is known (see, for example, Patent Document 1). The TDR method provides a step wave from one end of the transmission path of the measurement object to the transmission path, thereby observing the reflected wave of the step wave reflected by the other end of the transmission path at one end of the transmission path, and calculates the electrical length of the transmission path based on the time from the moment the step wave is provided to the moment the reflected wave is observed.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-024729 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] If there is no branch point in the transmission path of the existing communication network and the communication network is composed of one transmission path, the electrical length of the transmission path can be calculated by using the TDR method. However, since the communication network branches in the middle, the step wave is reflected at multiple line ends respectively to generate multiple reflected waves, and it is difficult to determine the reflected wave of the observation object that can be used to calculate the electrical length. Therefore, when the communication network branches in the middle, there is a problem that the electrical length of the transmission path cannot be measured by the TDR method.

[0009] The present disclosure has been made to solve the above-mentioned problem, and an object of the present disclosure is to obtain a transmission path length detection device capable of measuring the electrical length of a transmission path regardless of whether a communication network branches in the middle.

[0010] Means used to solve problems

[0011] The transmission path length detection device disclosed in the present invention comprises: a first electrostatic capacitance calculation unit, which observes the voltage change of the transmission path in the communication network and calculates the overall electrostatic capacitance of the transmission path, i.e., the total electrostatic capacitance, based on the voltage change; a second electrostatic capacitance calculation unit, which measures the characteristic impedance of the transmission path and calculates the electrostatic capacitance per unit length of the transmission path based on the characteristic impedance; and an electrical length calculation unit, which divides the total electrostatic capacitance calculated by the first electrostatic capacitance calculation unit by the electrostatic capacitance per unit length calculated by the second electrostatic capacitance calculation unit, thereby calculating the electrical length of the transmission path.

[0012] Effects of the Invention

[0013] According to the present disclosure, the electrical length of a transmission path can be measured regardless of whether a communication network branches in the middle. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 1 is a diagram showing a configuration of a communication system including the transmission path length detection device 3 according to the first embodiment.

[0015] Figure 2 1 is a hardware configuration diagram showing a part of the hardware of the transmission channel length detection device 3 according to the first embodiment.

[0016] Figure 3 This is a hardware configuration diagram of a computer when a part of the transmission path length detection device 3 is realized by software, firmware, or the like.

[0017] Figure 4 1 is a flowchart showing a part of the processing steps of the transmission path length detection device 3 .

[0018] Figure 5 1 is an explanatory diagram showing changes in the voltage V at the supply point of the constant current I0.

[0019] Figure 6 2 is an explanatory diagram showing changes in the voltage V' at the supply point of the step signal.

[0020] Figure 7 1 is an explanatory diagram showing changes in the voltage V at the supply point of the constant current I0.

[0021] Figure 8 1 is a diagram showing a configuration of another communication system including the transmission path length detection device 3 according to the first embodiment.

[0022] Fig. 9 It is a diagram showing the configuration of a communication system including the transmission path length detection device 3 according to the second embodiment.

[0023] Fig.10 This is a hardware configuration diagram showing a part of the hardware of the transmission channel length detection device 3 according to the second embodiment.

[0024] Fig.11 1 is a diagram showing the configuration of a communication system including a transmission path length detection device 3 according to a third embodiment.

[0025] Fig.12 1 is a hardware configuration diagram showing a part of the hardware of the transmission channel length detection device 3 according to the third embodiment. DETAILED DESCRIPTION

[0026] Hereinafter, in order to explain the present disclosure in more detail, the mode for implementing the present disclosure will be described with reference to the drawings.

[0027] Implementation method 1.

[0028] Figure 1 1 is a diagram showing a configuration of a communication system including the transmission path length detection device 3 according to the first embodiment.

[0029] Figure 1 The communication system shown includes a network communication device 1 , a transmission path 2 , and a transmission path length detection device 3 .

[0030] exist Figure 1 In the communication system shown, a plurality of network communication devices 1 are connected to a transmission path 2. The plurality of network communication devices 1 and the transmission path 2 form a communication network.

[0031] exist Figure 1 In the communication system shown, a plurality of network communication devices 1 are connected to the line ends of the transmission path 2. However, this is only an example, and the connection position between the network communication device 1 and the transmission path 2 is not particularly limited.

[0032] The communication network may be a bus network or a star network, or may be a single transmission path without any branches. However, the communication network is an existing communication network, and the line length of the transmission path 2 and the connection method of the transmission path 2 are unknown.

[0033] The network communication device 1 includes a transceiver unit 11 , a driver IC (Integrated Circuit) 12 , and a receiver IC 13 .

[0034] The transceiver 11 outputs a transmission signal to the transmission path 2 via the driver IC 12 .

[0035] The transceiver 11 receives a signal transmitted through the transmission path 2 via the receiver IC 13 .

[0036] The driver IC 12 outputs the transmission signal output from the transmission and reception unit 11 to the transmission path 2 .

[0037] The receiver IC 13 receives a signal transmitted through the transmission path 2 , and outputs the signal to the transceiver unit 11 .

[0038] The transmission channel length detection device 3 includes a first capacitance calculation unit 21 , a second capacitance calculation unit 22 , an electrical length calculation unit 23 , and a display unit 24 .

[0039] Figure 2 1 is a hardware configuration diagram showing a part of the hardware of the transmission channel length detection device 3 according to the first embodiment.

[0040] The first capacitance calculation unit 21 includes a switch 21 a , a constant current source 21 b , a voltage reference circuit 21 c , and a capacitance calculation processing unit 21 d .

[0041] The first electrostatic capacitance calculation unit 21 observes the voltage change of the transmission path 2 in the communication network, and calculates the total electrostatic capacitance C which is the entire electrostatic capacitance of the transmission path 2 based on the voltage change. total .

[0042] That is, the first electrostatic capacitance calculation unit 21 observes the voltage change at the supply point of the constant current I0 supplied to the transmission path 2 when the constant current I0 is supplied to the transmission path 2, and calculates the total electrostatic capacitance C of the transmission path 2 based on the voltage change. total .

[0043] The first electrostatic capacitance calculation unit 21 calculates the total electrostatic capacitance C total The first capacitance information is output to the electrical length calculation unit 23.

[0044] One end of the switch 21 a is connected to a probe 25 described later, and the other end of the switch 21 a is connected to a constant current source 21 b and a voltage reference circuit 21 c , respectively.

[0045] When a control signal outputted from a switch control unit 23 a (described later) of the electrical length calculation unit 23 indicates an on command, the switch 21 a is brought into a closed state.

[0046] If the control signal output from the switch control unit 23a indicates an OFF command, the switch 21a is turned on.

[0047] The constant current source 21 b is a current source that supplies a constant current I0 to the transmission path 2 via the switch 21 a and the probe 25 .

[0048] The voltage reference circuit 21 c observes a change in voltage at a supply point where the constant current I0 is supplied to the transmission path 2 when the constant current source 21 b outputs the constant current I0 .

[0049] The voltage reference circuit 21c measures the time Δt required for the voltage V at the supply point of the constant current I0 to change from 0 [V] to the reference voltage REF [V], and outputs the time Δt to the electrostatic capacitance calculation processing unit 21d.

[0050] The capacitance calculation processing unit 21d performs, for example, Figure 2 It is implemented by the first electrostatic capacitance calculation processing circuit 31 shown.

[0051] The capacitance calculation processing unit 21d multiplies the constant current I0, which is a known value, by the time Δt, and divides the multiplication result of the constant current I0 and the time Δt by the reference voltage REF, thereby calculating the total capacitance C total .

[0052] The capacitance calculation processing unit 21d calculates the total capacitance C total The first capacitance information is output to an electrical length calculation processing unit 23 b of the electrical length calculation unit 23 to be described later.

[0053] The second capacitance calculation unit 22 includes a switch 22a, a step signal source 22b, an analog-to-digital converter (hereinafter referred to as “ADC”) 22c, and a capacitance calculation processing unit 22d.

[0054] One end of the switch 22a is connected to the probe 25, and the other end of the switch 22a is connected to the step signal source 22b and the ADC 22c, respectively.

[0055] If the control signal output from the switch control unit 23a indicates an on command, the switch 22a is brought into a closed state.

[0056] If the control signal output from the switch control unit 23a indicates an OFF command, the switch 22a is turned on.

[0057] The step signal source 22b is a signal source that supplies a step signal to the transmission path 2 via the switch 22a and the probe 25. The step signal is a signal whose signal level changes suddenly from 0 to 1.

[0058] By supplying a step signal from the step signal source 22b to the transmission path 2, a reflected wave of the step signal reflected by the branch point of the transmission path 2 or a reflected wave of the step signal reflected by the line end of the transmission path 2 returns to the supply point of the step signal to the transmission path 2.

[0059] The ADC 22c converts the voltage at the supply point of the step signal from an analog signal to a digital signal.

[0060] The ADC 22c outputs a digital signal to the capacitance calculation processing unit 22d.

[0061] The capacitance calculation processing unit 22d performs, for example, Figure 2 It is implemented by the second electrostatic capacitance calculation processing circuit 32 shown.

[0062] The capacitance calculation processing unit 22 d determines the characteristic impedance Z0 of the transmission path 2 based on the digital signal output from the ADC 22 c .

[0063] The electrostatic capacitance calculation processing unit 22d calculates the electrostatic capacitance C per unit length of the transmission path 2 based on the characteristic impedance Z0. UL .

[0064] The capacitance calculation processing unit 22d calculates the capacitance C per unit length. UL The second capacitance information is output to the electrical length calculation processing unit 23 b of the electrical length calculation unit 23 .

[0065] The electrical length calculation unit 23 includes a switch control unit 23 a and an electrical length calculation processing unit 23 b .

[0066] The electrical length calculation unit 23 uses the total capacitance C calculated by the first capacitance calculation unit 21 to calculate total Divided by the capacitance C per unit length calculated by the second capacitance calculation unit 22 UL , from which the electrical length E of transmission path 2 is calculated L .

[0067] The switch control unit 23a performs the following operations, for example: Figure 2 The switch control circuit 33 shown is used to implement the above.

[0068] The switch control unit 23a outputs a control signal indicating an on command or a control signal indicating an off command to the switch 21a.

[0069] Furthermore, the switch control unit 23a outputs a control signal indicating an on command or a control signal indicating an off command to the switch 22a.

[0070] The electrical length calculation processing unit 23b performs, for example, Figure 2 The electrical length calculation processing circuit 34 is shown to achieve this.

[0071] The electrical length calculation processing unit 23b uses the total electrostatic capacitance C indicated by the first capacitance information output from the electrostatic capacitance calculation processing unit 21d. total Divide by the capacitance C per unit length indicated by the second capacitance information output from the capacitance calculation processing unit 22d UL , from which the electrical length E of transmission path 2 is calculated L .

[0072] The electrical length calculation processing unit 23 b outputs the electrical length E of the transmission path 2 to the display unit 24 . LThe display signal is displayed on the display unit 24.

[0073] The display unit 24 is realized by, for example, a liquid crystal display.

[0074] The display unit 24 displays the electrical length E of the transmission path 2 according to the display signal output from the electrical length calculation processing unit 23b. L .

[0075] The probe 25 is a device for supplying the constant current I0 output from the constant current source 21 b or the step signal output from the step signal source 22 b to the transmission path 2 .

[0076] exist Figure 1 In the embodiment, it is assumed that the electrostatic capacitance calculation processing unit 21d, the electrostatic capacitance calculation processing unit 22d, the switch control unit 23a and the electrical length calculation processing unit 23b, which are part of the structural elements of the transmission path length detection device 3, are respectively Figure 2 That is, it is assumed that part of the transmission path length detection device 3 is realized by the first electrostatic capacitance calculation processing circuit 31, the second electrostatic capacitance calculation processing circuit 32, the switch control circuit 33, and the electrical length calculation processing circuit 34.

[0077] The first electrostatic capacitance calculation processing circuit 31, the second electrostatic capacitance calculation processing circuit 32, the switch control circuit 33 and the electrical length calculation processing circuit 34 respectively correspond to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-ProgrammablEGatEArray), or a combination thereof.

[0078] Part of the structural elements of the transmission path length detection device 3 is not limited to being realized by dedicated hardware, and part of the transmission path length detection device 3 may be realized by software, firmware, or a combination of software and firmware.

[0079] Software or firmware is stored in the computer's memory in the form of a program. A computer refers to hardware that executes a program, such as a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor).

[0080] Figure 3 This is a hardware configuration diagram of a computer when a part of the transmission path length detection device 3 is realized by software, firmware, or the like.

[0081] When part of the transmission path length detection device 3 is implemented by software or firmware, a program for causing a computer to execute the processing steps of the electrostatic capacitance calculation processing unit 21d, the electrostatic capacitance calculation processing unit 22d, the switch control unit 23a, and the electrical length calculation processing unit 23b is stored in the memory 41. Then, the processor 42 of the computer executes the program stored in the memory 41.

[0082] Next, Figure 1 The operation of the communication system shown will be described.

[0083] Figure 4 1 is a flowchart showing a part of the processing steps of the transmission path length detection device 3 .

[0084] First, the switch control unit 23a outputs a control signal indicating an on command to the switch 21a, thereby setting the switch 21a to a closed state ( Figure 4 Step ST1).

[0085] In addition, the switch control unit 23a outputs a control signal indicating an off instruction to the switch 22a, thereby setting the switch 22a to an open state ( Figure 4 Step ST1).

[0086] The constant current source 21b supplies a constant current I0 to the transmission path 2 via the switch 21a and the probe 25 ( Figure 4 Step ST2).

[0087] The voltage reference circuit 21 c observes a change in voltage at a supply point where the constant current I0 is supplied to the transmission path 2 when the constant current source 21 b outputs the constant current I0 .

[0088] The supply point of the constant current I0 to the transmission path 2 is the setting point of the probe 25. Figure 5 As shown, the voltage V at the supply point of the constant current I0 increases monotonically from 0 [V] as time passes when the constant current I0 starts to be supplied. The voltage V becomes larger than the reference voltage REF [V] and then becomes a constant voltage.

[0089] Figure 5 1 is an explanatory diagram showing changes in the voltage V at the supply point of the constant current I0.

[0090] The voltage reference circuit 21c measures the time Δt (time Δt) required for the voltage V at the supply point of the constant current I0 to change from 0 [V] to the reference voltage REF [V]. Figure 4 Step ST3).

[0091] The voltage reference circuit 21c outputs the time Δt to the capacitance calculation processing unit 21d.

[0092] When the electrostatic capacitance calculation processing unit 21d receives the time Δt from the voltage reference circuit 21c, it multiplies the constant current I0, which is a known value, by the time Δt, and divides the multiplication result of the constant current I0 and the time Δt by the reference voltage REF [V], thereby calculating the total electrostatic capacitance C total [F]( Figure 4 Step ST4).

[0093]

[0094] The capacitance calculation processing unit 21d calculates the total capacitance C total The first capacitance information is output to the electrical length calculation processing unit 23b.

[0095] The switch control unit 23a outputs a control signal indicating an off instruction to the switch 21a, thereby setting the switch 21a to an open state ( Figure 4 Step ST5).

[0096] Furthermore, the switch control unit 23a outputs a control signal indicating an on command to the switch 22a, thereby setting the switch 22a to a closed state ( Figure 4 Step ST5).

[0097] The step signal source 22b supplies a step signal ( Figure 4 Step ST6).

[0098] By supplying a step signal from the step signal source 22 b to the transmission path 2, a reflected wave of the step signal reflected by a branch point of the transmission path 2 or a reflected wave of the step signal reflected by a line end of the transmission path 2 returns to the supply point of the step signal to the transmission path 2. The supply point of the step signal to the transmission path 2 is the setting point of the probe 25.

[0099] The voltage V' at the supply point of the step signal changes with time as follows: Figure 6 Change like that.

[0100] Figure 6 2 is an explanatory diagram showing changes in the voltage V' at the supply point of the step signal.

[0101] After the step signal is supplied from the step signal source 22 b to the transmission path 2 , the voltage V′ during a period until a reflected wave of the step signal reflected from the branch point of the transmission path 2 returns to the supply point of the step signal is V0 .

[0102] When the reflected wave of the step signal reflected by the branch point of the transmission path 2 returns to the supply point of the step signal, the voltage V' rises from V0 to V test .

[0103] Furthermore, if the line end of the transmission path 2 is an open end, for example, when the reflected wave of the step signal reflected by the open end returns to the supply point of the step signal, the voltage V' increases from V test Increase to 2×V0.

[0104] The ADC 22c converts the voltage V' at the supply point of the step signal from an analog signal to a digital signal.

[0105] The ADC 22c outputs a digital signal to the capacitance calculation processing unit 22d.

[0106] The capacitance calculation processing unit 22d determines the characteristic impedance Z0 [Ω] ( Figure 4 Step ST7).

[0107] The following specifically describes the process of determining the characteristic impedance Z0 performed by the electrostatic capacitance calculation processing unit 22d.

[0108] The electrostatic capacitance calculation processing unit 22d determines the voltage V0 when the step signal is supplied to the transmission path 2 by observing the waveform of the digital signal output from the ADC 22c. That is, the electrostatic capacitance calculation processing unit 22d determines the voltage V0 during the period from the time when the step signal is supplied to the transmission path 2 to the time when the reflected wave of the step signal reflected by the branch point returns to the supply point and the voltage V' at the supply point of the step signal rises.

[0109] Furthermore, the capacitance calculation processing unit 22d determines the voltage V when the reflected wave of the step signal reflected from the branch point returns to the supply point of the step signal by observing the waveform of the digital signal output from the ADC 22c. test That is, the electrostatic capacitance calculation processing unit 22d determines the voltage V during the period from the time when the reflected wave of the step signal reflected by the branch point returns to the supply point and the voltage V' of the supply point of the step signal rises to the time when the reflected wave of the step signal reflected by the line end returns to the supply point and the voltage V' of the supply point of the step signal rises. test .

[0110] The capacitance calculation processing unit 22d calculates the voltage V0 and the voltage V test Substituting into the following equation (2), the characteristic impedance Z0 of the transmission path 2 is calculated.

[0111]

[0112] In the formula (2), R is the resistance of the cable from the connection point between the step signal source 22 b and the ADC 22 c to the probe 25 , and is, for example, 50 [Ω].

[0113] Next, the capacitance calculation processing unit 22d calculates the capacitance C per unit length of the transmission path 2 from the characteristic impedance Z0 as shown in the following equation (3): UL [F / m]( Figure 4 Step ST8).

[0114]

[0115] In formula (3), v is the propagation speed of radio waves [m / s], ε r is the relative dielectric constant of transmission path 2.

[0116] The propagation speed of radio waves v and the relative dielectric constant ε r They may be stored in the internal memory of the electrostatic capacitance calculation processing unit 22 d , or may be provided from the outside of the transmission path length detection device 3 .

[0117] The capacitance calculation processing unit 22d calculates the capacitance C per unit length. UL The second capacitance information is output to the electrical length calculation processing unit 23b.

[0118] The electrical length calculation unit 23 obtains the first capacitance information from the electrostatic capacitance calculation processing unit 21 d , and obtains the second capacitance information from the electrostatic capacitance calculation processing unit 22 d .

[0119] The electrical length calculation unit 23 converts the total electrostatic capacitance C indicated by the first capacitance information into: total Divide by the electrostatic capacitance C per unit length indicated by the second capacitance information UL , from which the electrical length E of transmission path 2 is calculated L [m]( Figure 4 Step ST9).

[0120]

[0121] The electrical length calculation processing unit 23 b outputs the electrical length E of the transmission path 2 to the display unit 24 . L The display signal is displayed on the display unit 24.

[0122] The display unit 24 displays the electrical length E of the transmission path 2 according to the display signal output from the electrical length calculation processing unit 23b. L .

[0123] If the electrical length E of transmission path 2 is known L , it is possible to determine the transmission speed [m / s] of the signal transmitted and received by the network communication device 1 within the range in which the communication network can be treated as a lumped constant line (see Embodiment 2).

[0124] In the above-mentioned embodiment 1, the transmission path length detection device 3 is configured to include: a first electrostatic capacitance calculation unit 21, which observes the voltage change of the transmission path 2 in the communication network and calculates the overall electrostatic capacitance of the transmission path 2, that is, the total electrostatic capacitance based on the voltage change; a second electrostatic capacitance calculation unit 22, which measures the characteristic impedance of the transmission path 2 and calculates the electrostatic capacitance per unit length of the transmission path 2 based on the characteristic impedance; and an electrical length calculation unit 23, which divides the total electrostatic capacitance calculated by the first electrostatic capacitance calculation unit 21 by the electrostatic capacitance per unit length calculated by the second electrostatic capacitance calculation unit 22, thereby calculating the electrical length of the transmission path 2. Therefore, the transmission path length detection device 3 can measure the electrical length of the transmission path 2 regardless of whether the communication network is branched in the middle.

[0125] exist Figure 1 In the transmission path length detection device 3 shown in FIG. 1 , the first capacitance calculation unit 21 calculates the total capacitance C total Then, the second capacitance calculation unit 22 calculates the capacitance C per unit length. UL However, this is just an example, and the second capacitance calculation unit 22 may calculate the capacitance C per unit length. UL Then, the first electrostatic capacitance calculation unit 21 calculates the total electrostatic capacitance C total .

[0126] exist Figure 1 In the transmission path length detection device 3 shown in FIG. 1 , the first electrostatic capacitance calculation unit 21 observes the voltage change at the supply point of the constant current I0 supplied to the transmission path 2 when the constant current I0 is supplied to the transmission path 2, and calculates the total electrostatic capacitance C of the transmission path 2 based on the voltage change. total However, this is just an example, and the first electrostatic capacitance calculation unit 21 may also observe the voltage change at the supply point of the constant current I0 supplied to the transmission path 2 when the supply of the constant current I0 to the transmission path 2 is stopped, and calculate the total electrostatic capacitance C of the transmission path 2 based on the voltage change. total .

[0127] The calculation of the total capacitance C by the first capacitance calculation unit 21 will be described in detail below. total Calculation processing.

[0128] The constant current source 21 b stops supplying the constant current I0 to the transmission path 2 .

[0129] When the supply of the constant current I0 to the transmission path 2 is stopped, the voltage reference circuit 21c observes the voltage change at the supply point of the constant current I0 to the transmission path 2. Figure 7As shown, the voltage V at the supply point of the constant current I0 decreases monotonically with the passage of time when the supply of the constant current I0 is stopped. The voltage V becomes smaller than the reference voltage REF [V] and then becomes 0 [V].

[0130] Figure 7 1 is an explanatory diagram showing changes in the voltage V at the supply point of the constant current I0.

[0131] The voltage reference circuit 21c measures the time Δt required for the voltage V at the supply point of the constant current I0 to change from the reference voltage REF [V] to 0 [V].

[0132] The voltage reference circuit 21c outputs the time Δt to the capacitance calculation processing unit 21d.

[0133] When the electrostatic capacitance calculation processing unit 21d receives the time Δt from the voltage reference circuit 21c, it multiplies the constant current I0, which is a known value, by the time Δt as shown in formula (1), and divides the multiplication result of the constant current I0 and the time Δt by the reference voltage REF [V], thereby calculating the total electrostatic capacitance C total [F].

[0134] exist Figure 1 In the transmission path length detection device 3 shown in the figure, the second electrostatic capacitance calculation unit 22 determines the characteristic impedance Z0 of the transmission path 2 based on the reflected wave of the step signal that is reflected from the branch point of the transmission path 2 or the line end of the transmission path 2 and returns to the supply point of the step signal to the transmission path 2 when the step signal is supplied to the transmission path 2. However, this is just an example, and the second electrostatic capacitance calculation unit 22 may also determine the characteristic impedance Z0 of the transmission path 2 based on the reflected wave of the pulse signal that is reflected from the branch point of the transmission path 2 or the line end of the transmission path 2 and returns to the supply point of the pulse signal to the transmission path 2 when the pulse signal is supplied to the transmission path 2. The second electrostatic capacitance calculation unit 22 supplies the following pulse signal to the transmission path 2, and the time for which the signal level of the pulse signal becomes 1 is longer than the time Δt.

[0135] exist Figure 1 In the transmission path length detection device 3 shown in FIG. 1 , the electrical length calculation unit 23 calculates the electrical length E of the transmission path 2. L However, the electrical length E L The object of calculation of is not limited to the transmission path 2 as long as it has conductivity. Therefore, the electrical length calculation unit 23 may calculate the electrical length E of a metal pipe, for example. L .

[0136] exist Figure 1 In the communication system shown in FIG. 1 , the network communication device 1 and the transmission path length detection device 3 are different devices. However, this is only an example. Figure 8As shown, the network communication device 1 may also include a transmission path length detection device 3 .

[0137] Figure 8 1 is a diagram showing a configuration of another communication system including the transmission path length detection device 3 according to the first embodiment.

[0138] Implementation method 2.

[0139] In the second embodiment, a transmission channel length detection device 3 including an output cycle determination unit 26 for determining an output cycle of a signal output from a network communication device 1 to a transmission channel 2 is described.

[0140] Fig. 9 2 is a block diagram showing a communication system including a transmission path length detection device 3 according to Embodiment 2. Fig. 9 In, with Figure 1 and Figure 8 The same reference numerals denote the same or corresponding parts, and thus their descriptions are omitted.

[0141] Fig.10 FIG. 2 is a hardware configuration diagram showing a part of the hardware of the transmission path length detection device 3 according to the second embodiment. Fig.10 In, with Figure 2 The same reference numerals denote the same or corresponding parts, and thus their descriptions are omitted.

[0142] The output cycle determination unit 26 is configured to determine the output cycle by, for example, Fig.10 The output period determination circuit 35 shown is used to implement it.

[0143] The output cycle determination unit 26 determines the electrical length E calculated by the electrical length calculation processing unit 23 b of the electrical length calculation unit 23 based on the electrical length E calculated by the electrical length calculation processing unit 23 b. L , to determine the output cycle of the signal output from the network communication device 1 to the transmission path 2.

[0144] The output cycle determination unit 26 outputs cycle information indicating the determined output cycle to the transmission / reception unit 11 of the network communication device 1 .

[0145] exist Fig. 9 In the communication system shown in FIG. 1 , the output cycle determination unit 26 is applied to Figure 8 However, this is only an example, and the output cycle determination unit 26 can also be applied to Figure 1 The communication system shown.

[0146] exist Fig. 9 In the embodiment, it is assumed that the electrostatic capacitance calculation processing unit 21d, the electrostatic capacitance calculation processing unit 22d, the switch control unit 23a, the electrical length calculation processing unit 23b and the output cycle determination unit 26, which are part of the structural elements of the transmission path length detection device 3, are respectively composed of Fig.10 Specifically, it is assumed that part of the transmission path length detection device 3 is realized by a first electrostatic capacitance calculation processing circuit 31 , a second electrostatic capacitance calculation processing circuit 32 , a switch control circuit 33 , an electrical length calculation processing circuit 34 , and an output period determination circuit 35 .

[0147] The first electrostatic capacitance calculation processing circuit 31, the second electrostatic capacitance calculation processing circuit 32, the switch control circuit 33, the electrical length calculation processing circuit 34 and the output period determination circuit 35 respectively correspond to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0148] Part of the structural elements of the transmission path length detection device 3 is not limited to being realized by dedicated hardware, and part of the transmission path length detection device 3 may be realized by software, firmware, or a combination of software and firmware.

[0149] When part of the transmission path length detection device 3 is implemented by software or firmware, a program for causing a computer to execute the processing steps of the electrostatic capacitance calculation processing unit 21d, the electrostatic capacitance calculation processing unit 22d, the switch control unit 23a, the electrical length calculation processing unit 23b, and the output cycle determination unit 26 is stored in Figure 3 The memory 41 shown. Then, Figure 3 The processor 42 shown executes the program stored in the memory 41.

[0150] Next, Fig. 9 The operation of the communication system shown in FIG. Figure 1 or Figure 8 The communication systems shown are the same, and therefore, the operation of the output cycle determination unit 26 will be mainly described here.

[0151] The electrical length calculation processing unit 23b calculates the electrical length E of the transmission path 2. L When L The information is output to the output cycle determination unit 26.

[0152] The output cycle determination unit 26 receives the value indicating the electrical length E from the electrical length calculation processing unit 23b. L When the electrical length E L Substituting into the following equation (5), the minimum wavelength λ for which equation (5) holds true is calculated. λ is the wavelength of the signal v output from the network communication device 1 to the transmission path 2.

[0153] exist Fig. 9In the transmission path length detection device 3 shown, the output period determination unit 26 calculates the minimum wavelength λ for which the equation (5) holds true. However, any wavelength λ for which the equation (5) holds true is acceptable, and the output period determination unit 26 is not limited to the minimum wavelength λ. For example, the output period determination unit 26 may calculate a wavelength that is several percent greater than the minimum wavelength λ.

[0154]

[0155] Next, the output cycle determination unit 26 calculates the frequency f of the signal output from the network communication device 1 to the transmission path 2 by substituting the wavelength λ into the following equation (6).

[0156]

[0157] When calculating the frequency f of the signal, the output cycle determination unit 26 calculates the output cycle T of the signal output from the network communication device 1 to the transmission path 2 by substituting the frequency f into the following equation (7).

[0158]

[0159] The output cycle determination unit 26 outputs cycle information indicating the output cycle T of the signal to the transmission / reception unit 11 of the network communication device 1 .

[0160] When receiving the cycle information from the output cycle determination unit 26, the transceiver 11 of the network communication device 1 sets the output cycle of the transmission signal output to the transmission path 2 to the output cycle T indicated by the cycle information via the driver IC 12. Setting the output cycle of the transmission signal is equivalent to setting the transmission speed of the transmission signal.

[0161] Afterwards, the transceiver 11 outputs the transmission signal to the transmission path 2 via the driver IC 12 at the set output cycle T. For example, if the transmission signal is "101", the transceiver 11 transmits "0" at a time point after the output cycle T has passed after transmitting "1", and transmits "1" at a time point after the output cycle T has passed after transmitting "0".

[0162] In the above-mentioned Embodiment 2, the transmission path length detection device 3 is configured to include an output cycle determination unit 26, and the output cycle determination unit 26 determines the output cycle of the signal output from the network communication device 1 connected to the transmission path 2 to the transmission path 2 based on the electrical length calculated by the electrical length calculation unit 23. Therefore, regardless of whether the communication network is branched in the middle, the transmission path length detection device 3 can measure the electrical length of the transmission path 2, and further, can determine the transmission speed of the signal output from the network communication device 1 to a transmission speed within the range in which the communication network can be treated as a lumped constant line.

[0163] Implementation method 3.

[0164] In the third embodiment, a transmission path length detection device 3 including an abnormality detection unit 27 for detecting a wiring abnormality of a transmission path 2 or an illegal connection to the transmission path 2 will be described.

[0165] Fig.11 2 is a block diagram showing a communication system including a transmission path length detection device 3 according to Embodiment 3. Fig.11 In, with Figure 1 , Figure 8 as well as Fig. 9 The same reference numerals denote the same or corresponding parts, and thus their descriptions are omitted.

[0166] Fig.12 FIG. 2 is a hardware configuration diagram showing a part of the hardware of the transmission path length detection device 3 according to the third embodiment. Fig.12 In, with Figure 2 and Fig.10 The same reference numerals denote the same or corresponding parts, and thus their descriptions are omitted.

[0167] The abnormality detection unit 27 can be configured to detect the abnormality of the Fig.10 The abnormality detection circuit 36 ​​shown is implemented.

[0168] The abnormality detection unit 27 obtains the total capacitance C calculated by the first capacitance calculation unit 21. total , the characteristic impedance Z0 measured by the second electrostatic capacitance calculation unit 22, and the electrostatic capacitance C per unit length calculated by the second electrostatic capacitance calculation unit 22 UL .

[0169] The abnormality detection unit 27 detects the total electrostatic capacitance C total , characteristic impedance Z0 and electrostatic capacitance per unit length C UL , to detect wiring anomalies in transmission path 2 or illegal connections to transmission path 2.

[0170] The wiring abnormality of the transmission path 2 corresponds to disconnection or short circuit of the transmission path 2. The illegal connection to the transmission path 2 corresponds to a case where a computer or a communication device is illegally connected to the transmission path 2.

[0171] exist Fig.11 In the communication system shown in FIG. 1 , it is assumed that the electrical length calculation unit 23 first calculates the electrical length E L When , there is no wiring abnormality or the like in the transmission path 2. The abnormality detection unit 27 detects the wiring abnormality or the like that occurs thereafter.

[0172] exist Fig.11 In the communication system shown in FIG. 1 , the abnormality detection unit 27 is applied to Fig. 9However, this is just an example, and the abnormality detection unit 27 can also be applied to Figure 1 or Figure 8 The communication system shown.

[0173] exist Fig.11 In the embodiment, it is assumed that the capacitance calculation processing unit 21d, the capacitance calculation processing unit 22d, the switch control unit 23a, the electrical length calculation processing unit 23b, the output cycle determination unit 26 and the abnormality detection unit 27, which are part of the structural elements of the transmission path length detection device 3, are respectively Fig.12 That is, it is assumed that part of the transmission path length detection device 3 is implemented by the first electrostatic capacitance calculation processing circuit 31, the second electrostatic capacitance calculation processing circuit 32, the switch control circuit 33, the electrical length calculation processing circuit 34, the output period determination circuit 35 and the abnormality detection circuit 36.

[0174] The first electrostatic capacitance calculation processing circuit 31, the second electrostatic capacitance calculation processing circuit 32, the switch control circuit 33, the electrical length calculation processing circuit 34, the output period determination circuit 35 and the abnormality detection circuit 36 ​​respectively correspond to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0175] Part of the structural elements of the transmission path length detection device 3 is not limited to being realized by dedicated hardware, and part of the transmission path length detection device 3 may be realized by software, firmware, or a combination of software and firmware.

[0176] When part of the transmission path length detection device 3 is implemented by software or firmware, Figure 3 The memory 41 shown stores a program for causing the computer to execute the processing steps of the electrostatic capacitance calculation processing unit 21d, the electrostatic capacitance calculation processing unit 22d, the switch control unit 23a, the electrical length calculation processing unit 23b, the output cycle determination unit 26, and the abnormality detection unit 27. Then, Figure 3 The processor 42 is shown executing programs stored in the memory 41 .

[0177] Next, Fig.11 The operation of the communication system shown in FIG. Figure 1 , Figure 8 or Fig. 9 The communication systems shown are the same, and therefore, the operation of the abnormality detection unit 27 will be mainly described here.

[0178] The abnormality detection unit 27 obtains the total capacitance C calculated by the first capacitance calculation unit 21. total, the characteristic impedance Z0 measured by the second electrostatic capacitance calculation unit 22, and the electrostatic capacitance C per unit length calculated by the second electrostatic capacitance calculation unit 22 UL .

[0179] The abnormality detection unit 27 calculates the total electrostatic capacitance C total Set as the initial total electrostatic capacitance C total ' and stored in the internal memory, the characteristic impedance Z0 is set as the initial characteristic impedance Z0' and stored in the internal memory.

[0180] In addition, the abnormality detection unit 27 calculates the electrostatic capacitance C per unit length. UL Set as the initial electrostatic capacitance C UL 'And stored in internal memory.

[0181] Thereafter, the abnormality detection unit 27 repeatedly obtains the total capacitance C newly calculated by the first capacitance calculation unit 21. total , the characteristic impedance Z0 newly measured by the second electrostatic capacitance calculation unit 22, and the electrostatic capacitance per unit length C newly calculated by the second electrostatic capacitance calculation unit 22 UL .

[0182] The abnormality detection unit 27 obtains the total electrostatic capacitance C each time total , characteristic impedance Z0 and electrostatic capacitance per unit length C UL When the total electrostatic capacitance C is calculated total The initial total electrostatic capacitance C total The difference between ΔC total .

[0183] Furthermore, the abnormality detection unit 27 calculates the difference ΔZ0 between the acquired characteristic impedance Z0 and the initial characteristic impedance Z0′, and calculates the acquired electrostatic capacitance C per unit length. UL With the initial electrostatic capacitance C UL The difference between ΔC UL .

[0184] The abnormality detection unit 27 detects the difference ΔC total Compared with the first threshold Th1, if the difference ΔC total If it is larger than the first threshold value Th1, it is determined that there is a wiring abnormality in the transmission path 2 or an illegal connection to the transmission path 2.

[0185] The abnormality detection unit 27 compares the difference ΔZ0 with the second threshold Th2 and determines that there is a wiring abnormality in the transmission path 2 or an illegal connection to the transmission path 2 if the difference ΔZ0 is larger than the second threshold Th2.

[0186] The abnormality detection unit 27 detects the difference ΔC ULCompared with the third threshold Th3, if the difference ΔC UL If it is larger than the third threshold value Th3, it is determined that there is a wiring abnormality in the transmission path 2 or an illegal connection to the transmission path 2.

[0187] If the difference ΔC total is less than the first threshold value Th1, the difference ΔZ0 is less than the second threshold value Th2, and the difference ΔC UL If the value is equal to or smaller than the third threshold value Th3, the abnormality detecting unit 27 determines that neither the wiring abnormality of the transmission path 2 nor the illegal connection to the transmission path 2 exists.

[0188] The first threshold value Th1 , the second threshold value Th2 , and the third threshold value Th3 may be stored in an internal memory of the abnormality detection unit 27 , or may be provided from outside the transmission path length detection device 3 .

[0189] When determining that there is a wiring abnormality in the transmission path 2 or an illegal connection to the transmission path 2 , the abnormality detection unit 27 causes the display unit 24 to display a determination result indicating this.

[0190] When determining that neither the wiring abnormality of the transmission path 2 nor the illegal connection to the transmission path 2 exists, the abnormality detection unit 27 causes the display unit 24 to display a determination result indicating this.

[0191] In the above-mentioned third embodiment, the transmission path length detection device 3 is configured to include an abnormality detection unit 27, and the abnormality detection unit 27 detects a wiring abnormality of the transmission path 2 or an illegal connection to the transmission path 2 based on the total electrostatic capacitance calculated by the first electrostatic capacitance calculation unit 21, the characteristic impedance measured by the second electrostatic capacitance calculation unit 22, and the electrostatic capacitance per unit length calculated by the second electrostatic capacitance calculation unit 22. Therefore, the transmission path length detection device 3 can measure the electrical length of the transmission path 2 regardless of whether the communication network branches in the middle, and can also detect a wiring abnormality of the transmission path 2 or an illegal connection to the transmission path 2.

[0192] In the communication systems of Embodiments 1 to 3, the second electrostatic capacitance calculation unit 22 includes a step signal source 22b that supplies a step signal to the transmission path 2. However, this is just an example, and the second electrostatic capacitance calculation unit 22 may obtain a data pattern simulating a step signal from the transceiver 11 of the network communication device 1, and supply a signal representing the data pattern as a step signal to the transmission path 2. The data pattern simulating a step signal is, for example, a data pattern such as 0111...

[0193] In addition, the present disclosure allows free combination of the various embodiments, modification of arbitrary components of the various embodiments, or omission of arbitrary components in the various embodiments.

[0194] Industrial Applicability

[0195] The present invention discloses a transmission path length detection device suitable for calculating the electrical length of a transmission path.

[0196] Furthermore, the present disclosure is applicable to a network communication device including a transmission path length detection device.

[0197] Description of Reference Numerals

[0198] 1 network communication device, 2 transmission path, 3 transmission path length detection device, 11 transceiver, 12 driver IC, 13 receiver IC, 21 first electrostatic capacitance calculation unit, 21a switch, 21b constant current source, 21c voltage reference circuit, 21d electrostatic capacitance calculation processing unit, 22 second electrostatic capacitance calculation unit, 22a switch, 22b step signal source, 22c ADC, 22d electrostatic capacitance calculation processing unit, 23 electrical length calculation unit, 23a switch control unit, 23b electrical length calculation processing unit, 24 display unit, 25 probe, 26 output cycle determination unit, 27 abnormality detection unit, 31 first electrostatic capacitance calculation processing circuit, 32 second electrostatic capacitance calculation processing circuit, 33 switch control circuit, 34 electrical length calculation processing circuit, 35 output cycle determination circuit, 36 abnormality detection circuit, 41 memory, 42 processor.

Claims

1. A transmission path length detection device, wherein: The transmission path length detection device comprises: a first electrostatic capacitance calculation unit that observes a voltage change in a transmission path in a communication network and calculates a total electrostatic capacitance that is an entire electrostatic capacitance of the transmission path based on the voltage change; a second electrostatic capacitance calculation unit that measures a characteristic impedance of the transmission path and calculates an electrostatic capacitance per unit length of the transmission path based on the characteristic impedance; as well as an electrical length calculation unit that calculates the electrical length of the transmission path by dividing the total electrostatic capacitance calculated by the first electrostatic capacitance calculation unit by the electrostatic capacitance per unit length calculated by the second electrostatic capacitance calculation unit, The second electrostatic capacitance calculation unit determines the characteristic impedance of the transmission path based on a reflected wave of the step signal that is reflected from a branch point of the transmission path or a line end of the transmission path and returns to a supply point of the step signal to the transmission path when the step signal is supplied to the transmission path, and calculates the electrostatic capacitance per unit length of the transmission path based on the characteristic impedance.

2. The transmission path length detection device according to claim 1, characterized in that: The transmission channel length detection device includes an output cycle determination unit that determines an output cycle of a signal output from a network communication device connected to the transmission channel to the transmission channel based on the electrical length calculated by the electrical length calculation unit.

3. The transmission path length detection device according to claim 1, characterized in that: The transmission path length detection device includes an abnormality detection unit, which detects wiring abnormalities of the transmission path or illegal connections to the transmission path based on the total electrostatic capacitance calculated by the first electrostatic capacitance calculation unit, the characteristic impedance measured by the second electrostatic capacitance calculation unit, and the electrostatic capacitance per unit length calculated by the second electrostatic capacitance calculation unit.

4. The transmission path length detection device according to claim 2, characterized in that: The transmission path length detection device includes an abnormality detection unit, which detects wiring abnormalities of the transmission path or illegal connections to the transmission path based on the total electrostatic capacitance calculated by the first electrostatic capacitance calculation unit, the characteristic impedance measured by the second electrostatic capacitance calculation unit, and the electrostatic capacitance per unit length calculated by the second electrostatic capacitance calculation unit.

5. The transmission path length detection device according to any one of claims 1 to 4, characterized in that: The first electrostatic capacitance calculation unit observes a voltage change at a supply point of the constant current to the transmission path when the constant current is supplied to the transmission path, and calculates a total electrostatic capacitance of the transmission path based on the voltage change.

6. The transmission path length detection device according to any one of claims 1 to 4, characterized in that: The first electrostatic capacitance calculation unit observes a voltage change at a supply point of the constant current to the transmission path when supply of the constant current to the transmission path is stopped, and calculates a total electrostatic capacitance of the transmission path based on the voltage change.

7. The transmission path length detection device according to claim 1, characterized in that: The second capacitance calculation unit includes a step signal source that supplies the step signal to the transmission path.

8. A network communication device, characterized in that: The network communication device comprises: a transceiver unit that outputs a signal to a transmission path of a communication network and receives a signal transmitted in the transmission path; and a transmission path length detection device for calculating the electrical length of the transmission path, The transmission path length detection device is the transmission path length detection device according to any one of claims 1 to 7.

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