JP6182122B2 - Interference wave transfer characteristic measurement system and measurement method - Google Patents

Description

  The present invention relates to an interference wave transfer characteristic measurement system and measurement method, and more particularly, to a measurement system and a measurement method for evaluating the transfer characteristics of electromagnetic interference waves unintentionally generated by an electric / electronic device.

  Conventionally, it is known that electromagnetic interference waves (hereinafter referred to as interference waves) unintentionally generated by electric / electronic devices intrude into communication devices, broadcasting devices, etc., causing communication failures, radio wave interferences, and the like. For the purpose of preventing these obstacles, a method for evaluating interference waves generated by electrical and electronic equipment is defined by the International Radio Interference Special Committee (CISPR) standards and the like. In CISPR32 (Non-Patent Document 1), a common mode in which a conductive disturbance wave that enters a power port and a communication port of a communication / broadcasting device is generated between the power line and the ground and between the communication line and the ground, respectively. It is defined as an interference wave in a propagation mode in which the component is dominant. For this reason, countermeasures against interference waves have been taken by using a common mode filter between the power line and the ground and between the communication line and the ground.

  On the other hand, the state of the source of the disturbing wave that affects the communication device, the broadcasting device and the like is also changing. For example, a radio wave generated by a high-speed broadband wireless system such as a smartphone or a wireless LAN, or a wireless sensor network such as ZigBee may become an interference wave for a communication device, a broadcasting device, or the like. There are many occasions where such a wireless system is used very close to a communication device, a broadcasting device, and the like, which may cause a communication failure, a radio wave interference, etc. in the communication device, the broadcasting device, and the like. In addition, as represented by the popularization of solar power generation systems and plug-in hybrid cars, highly efficient power supply systems have been installed in various places. Unintentional interference waves generated from inverters and converters built in these power supply systems are also increasing. In particular, the interference wave generated by the power supply system is increased in output and may be generated very close to the communication device, broadcasting device, etc., so it can enter the communication device, broadcasting device, etc. via various intrusion routes. there's a possibility that.

CISPR 32 Ed1.0, "Electromagnetic compatibility of multimedia equipment-Emission requirements," 2012. CISPR 16-1-2 Ed 2.0, “Specification for radio disturbance and immunity measuring apparatus and methods-Part 1-2: Radio disturbance and immunity measuring apparatus-Coupling devices for conducted disturbance measurements,” 2014. CISPR 24 Ed 2.0, “Information technology equipment-Immunity characteristics-Limits and methods of measurement,” 2010. CISPR 16-2-1 Ed 3.0, “Specification for radio disturbance and immunity measuring apparatus and methods-Part 2-1: Methods of measurement of disturbances and immunity-Conducted disturbance measurements,” 2014.

  In the conventional interference wave evaluation method, the common mode component generated between the power line and the ground and between the communication line and the ground has been evaluated as a dominant propagation mode interference wave. However, communication ports of devices having communication functions have been diversified due to the fusion of communication and broadcasting, the speeding up and diversification of communication networks. For example, an Ethernet (registered trademark) port connected to a LAN, a USB port to which various accessory devices are connected, an HDMI (registered trademark) / coaxial port to which a video device is connected, and the like are known. Such communication ports are not connected to a pair (two wires) of communication cables as in a conventional POTS (Plain Old Telephone Service) port, but are connected to a multi-pair cable of various shapes.

  The return path of the common mode interference wave propagating in the same phase through a pair of cables in a multi-pair cable is roughly divided into two, the ground and the other line (conductor) in the vicinity. Here, the common mode having the other line in the vicinity as the return path is referred to as a primary common mode, and the common mode having the ground as a return path is referred to as a secondary common mode. There are three types of modes in which the interference wave can propagate: primary common mode (Primary common-mode), secondary common mode (Secondary common-mode), and differential mode (Differential-mode) that propagates differentially. Of these, it is not clear which propagation mode is dominant as a component of the interference wave, and which interference mode has a high correlation with communication failure, radio interference, and the like. For this reason, a new evaluation technique is required for interference waves that enter in such various propagation modes.

  FIG. 1 shows an intrusion path of an interference wave. There are a plurality of paths through which conductive interference waves are mixed in communication apparatuses, broadcasting apparatuses, and the like. For example, let us consider mixing from other communication devices connected by a many-pair communication line such as an Ethernet (registered trademark) cable. As shown in FIG. 1, an interfering wave that interferes with a disturbed device 1 such as a communication device or a broadcasting device is emitted from an inverter / converter 4 that is a source of the disturbing wave, and is transmitted to the disturbed device 1 via a distribution board 3. It enters from the power supply system of the connected communication device 2. This interference wave is transmitted to the communication port of the communication device 2 via electromagnetic coupling inside the communication device 2, and is transmitted to the communication port of the disturbed device 1 via the many-pair communication line 6.

  At this time, it is considered that the common mode is dominant in the interference wave at the time when it is emitted from the inverter / converter 4 serving as the interference wave source to the power supply line 5. However, since various conductors exist inside the communication device 2, there is a possibility that the propagation mode is converted by electromagnetic coupling inside the communication device 2. In addition, since the propagation modes when transmitting through the many-pair communication line 6 are also diversified, the dominant propagation mode and transmission characteristics of the disturbing wave affecting the disturbed device 1 become complicated and unclear. Therefore, there has been a problem that it is difficult to determine countermeasures against jamming waves, such as elucidating the mechanism of occurrence of communication faults, radio wave jamming, etc., and determining which mode to deal with jamming waves.

  An object of the present invention is to transmit jamming waves for stably evaluating the transmission characteristics of jamming waves mixed from a power supply line of a communication device, passing through the inside of the communication device, and transmitted to the communication line with good reproducibility. A characteristic measurement system and a measurement method are provided.

  In order to achieve such an object, the present invention provides a communication device in which a power supply line for receiving power supply and a communication line for communication with other devices are connected to each other from the power supply line. An interference wave transfer characteristic measurement method for evaluating the transfer characteristic of an interference wave transmitted through the communication device and transmitted to the communication line, as a physical port for measurement in the communication device, Define the power supply line side power port and the communication line side communication port, and measure the transmission characteristics separately for each propagation mode of the interference wave consisting of differential mode, primary common mode, and secondary common mode Defining a mixed mode port for the transmission, and converting an S parameter corresponding to the physical port into an S parameter corresponding to the mixed mode port, Characterized by comprising measuring the transmission characteristics of Dogoto.

Vector addition, one embodiment of the interference wave transfer characteristic measurement system, comprising a first port connected to the power supply line of the communication device, and a second and third port connected to said communication line A network analyzer, an absorption clamp inserted in a coaxial cable connecting the power supply line and the first port, and the communication line, the second port, the communication line, and the third port are connected to each other. A grounding means for connecting the shield of the coaxial cable and the system ground with low impedance is provided.

  As described above, according to the present invention, the transmission characteristic of the interference wave mixed from the power line of the communication device, passing through the inside of the communication device, and transmitted to the communication line can be stably evaluated with good reproducibility. can do. In particular, according to the interference wave transfer characteristic measurement method, it is possible to evaluate each propagation mode of each port, so that it is easy to determine which countermeasure is to be taken against which interference wave in which propagation mode of which port.

  Further, according to the interference wave transfer characteristic measurement system, the secondary common mode of the coaxial cable on the power line side is reduced, and the termination condition of the secondary common mode of the coaxial cable on the communication line side is short-circuited. By suppressing the resonance of the next common mode current, the transfer characteristic can be stably measured with good reproducibility.

It is a figure which shows the penetration | invasion path | route of an interference wave. It is a figure which shows the physical port on the basis of a system ground. It is a figure which shows the mixed mode port for every propagation mode. It is a figure which shows the termination conditions of a power supply port. It is a figure which shows the termination conditions of a communication port. It is a figure which shows the mode voltage and electric current of differential mode. It is a figure which shows the mode voltage and electric current of a common mode. It is a figure which shows the relationship between the characteristic impedance of each mode, and height h. It is a figure which shows the interference wave transfer characteristic measuring system in one Embodiment of this invention. It is a figure which shows the measurement result of transfer characteristic | _SCS | of three types of switching hubs. It is a figure which shows the measurement result of transfer characteristic | _SDS | of three types of switching hubs. Transfer characteristics of the switching hub DUT1 _| is a diagram showing the measurement results | _{S CS} | and _{| S DS.} Transfer characteristics of the switching hub DUT 2 _| is a diagram showing the measurement results | _{S CS} | and _{| S DS.} Transfer characteristics of the switching hub DUT 3 _| is a diagram showing the measurement results | _{S CS} | and _{| S DS.} It is a figure which shows the interference wave transmission characteristic measurement system which comprised the measurement system prescribed | regulated by CISPR16-2-1. Transfer characteristics of the switching hub DUT1 by CISPR16-2-1 _| is a diagram showing the measurement results | _{S CS} | and _{| S DS.} Transfer characteristics of the switching hub DUT1 when varying installation conditions CDNE _| is a diagram showing the measurement results | _{S CS} | and _{| S DS.}

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As described above, depending on the path of the disturbing wave that enters the disturbed device, the transfer characteristics including the propagation mode of the disturbing wave are complicated and unclear. Hereinafter, an evaluation method for clarifying the transmission characteristics of the conductive interference wave will be described by taking a communication device connected to the disturbed device by a many-pair communication line as an example.

  Communication devices are often installed at a distance from a large ground serving as a reference potential to some extent in general homes and general office buildings. At this time, the communication device is placed at a certain distance on the system ground serving as the reference potential, and it can be considered that the casing does not have a direct connection with the system ground. Also, the communication device is connected to a two-wire or three-wire alternating current (AC) power wire for receiving power supply, and a communication wire such as an Ethernet (registered trademark) cable for communication with the disturbed device. It is connected. Here, the communication line is a shielded twisted pair (STP) Ethernet (registered trademark) cable, and unless otherwise specified, the AC power line and communication line are on a straight line at a fixed distance from the system ground. Consider the case where

  At this time, in order to evaluate the characteristic that the interference wave mixed into the power supply system from the AC power supply line is transmitted to the communication line such as the Ethernet (registered trademark) cable, a measurement port is defined on each of the AC power supply line side and the communication line side. There is a need. Here, as shown below, a physical port for measurement (AC power supply port, communication port) and a mixed mode port (differential mode, primary common mode, secondary common mode) for separating each propagation mode And define

[Definition of physical port and mixed mode port for measurement]
A) AC power port
A1) In the case of a 3-wire power cable (L (Live) wire, N (Neutral) wire, PE (Protection Earth) wire)
FIG. 2 shows a physical port based on the system ground. Considering the case where the grounding of the communication device 11 to be evaluated is incomplete, the PE line of the AC power line 12 is unlikely to be the same potential as the system ground 14. Therefore, when these three wires are handled equally to the system ground 14, as shown in FIG. 2, the physical ports (# p1 to # p3) are defined between each line of the AC power supply line 12 and the system ground 14. Is done. However, when considering interfering waves mixed from the power supply system, in order to consider mixing of common mode interfering waves in which all lines are in phase, conversion from a physical port to a mixed mode port is considered.

FIG. 3 shows a mixed mode port for each propagation mode. When the power supply line connected to the communication device can be regarded as a transmission line, it can be separated into three propagation modes, so a mixed mode port corresponding to it is defined. The voltage with respect to the system ground of each line of the AC power supply line 12 is V ₁ (L), V ₂ (N), V ₃ (PE), and the current is I ₁ (L), I ₂ (N), I ₃ (PE). Then, the propagation mode of the transmission line can be described as follows.

A11) Differential mode
When reverse-phase voltages with the same amplitude are applied to the two wires (L-line and N-line) except for the PE line, and a negative-phase current is generated with the same amplitude, the Kirchoff current law indicates that the PE line and the system ground There is no current flowing through. That is, the differential mode voltage V _D and the differential mode current _ID can be described by each voltage and current as in the following equations.

A12) Primary common mode
Kirchhoff's current is applied to two lines (L line and N line) excluding the PE line when an in-phase voltage with the same amplitude is applied, an in-phase current is generated with the same amplitude, and the PE line serves as a current return path. As a rule, no current flows through the system ground. That is, the primary common mode voltage V _CP and the primary common mode current I _CP can be described by the following equations.

A13) Secondary common mode
When all three wires have the same amplitude and the same phase voltage applied, and the same amplitude and the same phase current flow, the return path of this current becomes the system ground. Therefore, the secondary common mode voltage V _CS and the secondary common mode current I _CS are described by the following equations.

A2) Two-wire power cable (L (Live) wire, N (Neutral) wire)
When the power supply terminal of the communication device is not equipped with a PE line, a propagation mode for a 2-wire power cable is defined. In this case, the physical ports are two ports based on the system ground as in the case of the three-wire power cable. However, since the mixed mode port can define only two propagation modes, only the differential mode and the common mode can be defined as described below. Similarly, if the voltage of each line is V ₁ (L), V ₂ (N), and the current is I ₁ (L), I ₂ (N), the propagation mode of the transmission line can be described as follows.

A21) Differential mode
As in the case of 3-wire, when a negative-phase voltage is applied to the L-line and N-line, and a negative-phase current flows with the same amplitude, no current flows to the system ground from Kirchhoff's current law. . That is, the differential mode voltage V _D and the differential mode current _ID can be described by each voltage and current as in the following equations.

A22) Secondary common mode
When in-phase voltage with the same amplitude is applied to the two wires and a current of the same phase flows with the same amplitude, the return path of this current becomes the system ground. Therefore, the secondary common mode voltage V _C and the secondary common mode current I _C are described by the following equations.

B) Communication port
When the communication line is an STP cable composed of four pairs of pair lines and a shield, the physical port of the communication line 13 has eight communication ports with each communication line and the shield line as physical ports (# c1 to # c8). 16 (see FIGS. 2 and 3). Here, it is assumed that the shield wire is connected to the system ground or the measurement system ground with a low impedance. In actual communication, considering that communication signals are transmitted between two paired wires, a mixed mode port corresponding to the communication signal should be set. Therefore, a port corresponding to the propagation mode is defined in consideration of only two pair lines and a shield line.

  Here, as an advantage of using the STP cable, since most of the return current of the primary common mode flows through the shield line of the STP cable, it becomes easy to fix the terminal impedance between the shield line and the communication line, and the mode This is because it is easy to define. On the other hand, in the case of unshielded twisted pair (UTP) cable, the return current of the primary common mode flows to the other 6 wires. If the termination impedance is not defined, the problem that the transfer characteristic cannot be evaluated remains.

In addition, the basic concept is the same as the mode separation of the 3-wire power cable, but the shielded wire has a sufficiently thick structure compared to the communication wire, compared to the nearly symmetrical 3-wire power cable. There is a difference. The voltage of each line is V ₁ (communication line 1), V ₂ (communication line 2), V ₃ (shield), and the current is I ₁ (communication line 1), I ₂ (communication line 2), I ₃ (shield). ).

B1) Differential mode
When a reverse phase voltage with the same amplitude is applied to the two communication lines and a reverse phase current flows with the same amplitude, no current flows through the shield and the system ground from Kirchhoff's current law. That is, the differential mode voltage V _D and the differential mode current _ID are described by the respective voltages and currents as in the following equations.

B2) Primary common mode
A voltage having the same amplitude and the same phase is applied to the two communication lines, and a current having the same amplitude and the same phase flows. The return path of this current is a shield. Therefore, no current flows through the system ground according to Kirchhoff's current law. That is, primary common mode voltage V _CP and primary common mode current I _CP are described by the following equations.

B3) Secondary common mode
When a common-mode voltage with the same amplitude is applied to all lines including the shield, and a common-mode current flows with the same amplitude, the return path of this current becomes the system ground. Here, in the case of the STP cable, since the shield wire covers eight wires, all current flows through the shield wire. Therefore, the secondary common mode voltage V _CS and the secondary common mode current I _CS are described by the following equations.

[Determining termination conditions for each port]
Next, in order to construct a highly reproducible evaluation system, it is necessary to determine the termination conditions for each port described above. Hereinafter, a method of determining termination conditions of a mixed mode port (differential mode, primary common mode, secondary common mode) with respect to a physical port (AC power supply port, communication port) using two power lines will be described.

A) AC power port
In CISPR16-1-2 (Non-Patent Document 2), an interference wave application circuit (CDNE: Coupling / Decoupling) for conducting a 30 to 300 MHz conducted disturbance wave emitted by an EUT (Equipment Under Test) having a transmission source of 30 MHz or less. Network for Emission Measurement) characteristics are specified.

  FIG. 4 shows the termination conditions of the power supply port. Here, a method of determining the termination condition using the CDNE 17 on the power supply side of the communication apparatus 11 is shown. Here, the AC power line 12 is connected to the power line from the distribution board via the outlet 18, and the AC power line 12 to be evaluated is a physical port (# 1).

A1) Differential mode
When CDNE is used, the termination condition of the differential mode port is defined as high impedance, and the influence on the commercial power supply side can be excluded.

A2) Common mode
CDNE stipulates that the common-mode termination impedance is 150Ω in the frequency range of 30 to 300 MHz.

B) Communication port
FIG. 5 shows the termination conditions of the communication port. Most common measuring instruments such as a vector network analyzer (VNA) have a maximum of 4 ports, and the number of ports that can be measured simultaneously is limited. In a system with only eight communication lines, the number of measurements increases, which is not realistic. Therefore, by using the symmetry of the STP cable, only two arbitrary communication lines are evaluated, and the remaining six lines are terminated at 50Ω. Here, the two lines to be evaluated are physical ports (# 2 and # 3) corresponding to the shield line and the communication line, respectively.

B1) Differential mode
As shown in FIG. 5 (a), in the differential mode, current flows through two lines as a loop, and therefore, the terminating resistance (R = 50Ω) of each line is inserted in series, so that the terminating impedance is 100Ω. Become.

B2) Primary common mode
As shown in FIG. 5B, in the case of the primary common mode, since the same current flows from each of the two lines toward the system ground 14, the terminating resistance (R = 50Ω) of each line is inserted in parallel. Therefore, the termination impedance is 25Ω.

B3) Secondary common mode
The termination impedance of the secondary common mode is not stabilized because the shield of the STP cable is connected to the measurement system ground via parasitic coupling. In this case, the termination condition can be short-circuited by connecting the outer sheath of the coaxial cable connected to a measuring device such as a vector network analyzer to the system ground with low impedance.

  As described above, a physical port for measurement (AC power port) is used to evaluate the characteristics of interference waves mixed from the AC power line into the power system to the multi-pair communication line such as an Ethernet (registered trademark) cable. , Communication ports) and mixed mode ports (differential mode, primary common mode, secondary common mode) for separating each propagation mode, and the termination conditions thereof are defined.

[Definition of propagation mode in cable]
Next, the cable propagation mode corresponding to the port definition will be described. Considering a system in which two-wire cables are wired on a straight line at a certain distance from the system ground, their propagation modes can be defined as a differential mode and a common mode. When the cable is sufficiently long and straightly wired at a constant distance from the system ground while maintaining symmetry, mode conversion in the transmission path does not occur. Therefore, it is only necessary to consider mode conversion at the outlet terminals at both ends of the cable, the connection connector with the communication device, and the like.

FIG. 6 shows the mode voltage / current in the differential mode. The differential mode current flows through the two wires with the same amplitude and in opposite phases. As shown in FIG. 6, since the system is symmetrical, the voltage from the system ground of each line also has the same amplitude and opposite phase. Here, the differential mode voltage can be expressed by a line voltage, and is indicated by V _D in FIG. _ID represents a differential mode current.

FIG. 7 shows the mode voltage and current in the common mode. Since the common mode is a propagation mode in which the voltage of each line is equal, when the system is symmetrical, currents having the same amplitude and the same phase flow through the lines. In FIG. 7, V _C represents a common mode voltage, and I _C represents a common mode current.

The characteristic impedance of each mode is expressed by the following equation using the capacitances c ₁₁ and c ₂₂ between the lines and the system ground, the inter-line capacitance c ₁₂ , the self-inductances L ₁₁ and L _{22 of} each line, and the mutual inductance L _12. Can express.

Here, when the system is symmetrical, c ₁₁ and c ₂₂ and L ₁₁ and L ₂₂ are equal. Further, these line primary constants can be obtained by electrostatic field analysis based on the cross-sectional shape of the transmission line.

  FIG. 8 shows the relationship between the characteristic impedance of each mode and the height h of the cable from the system ground. It can be seen that the differential mode characteristic impedance hardly changes with respect to the height h, and the common mode characteristic impedance changes greatly. In particular, when the height h is low, the rate of change is large, suggesting that transmission characteristics vary greatly depending on the height of the cable. Therefore, in this embodiment, the reproducibility of the transfer characteristics is improved by fixing the height of the cable.

[Interference wave transfer characteristic measurement system]
FIG. 9 shows an interference wave transfer characteristic measurement system according to an embodiment of the present invention. The interference wave transfer characteristic measurement system uses the vector network analyzer 31 to evaluate the transfer characteristic of the interference wave from the AC power supply port of the communication device 21 to the communication port. One port of the vector network analyzer 31 is connected to the AC power port (physical port # 1 in FIG. 4) of the communication device 21 to be evaluated via the CDNE 27, and a common mode signal (such as an interference wave) is connected to the vector network analyzer 31. It can be injected into the power line. At this time, in order to reduce the secondary common mode transmitted to the outer sheath of the coaxial cable connected to the port, the absorption clamp 32 is installed.

  The other two ports of the vector network analyzer 31 are connected to the many-pair communication line 23 of the communication device 21 via the coaxial cable connector 34 provided on the copper plate 33 and the RJ45-SMA conversion board 35. . For example, two coaxial cable connectors 34, which are SMA connectors, are installed on a copper plate 33 having high conductivity, and constitute a grounding means. That is, the shield of the coaxial cable connecting the other two ports of the vector network analyzer 31 and the many-pair communication line 23 is connected to the system ground 24 with low impedance. Thereby, the termination condition of the secondary common mode on the communication port side of the communication device 21 to be evaluated can be brought into a short circuit state.

  Here, the advantage of using the copper plate 33 is that it does not propagate the electromagnetic waves of the second-order common mode in the direction of the vector network analyzer 31 and flows through the entire measurement system, in particular, a coaxial cable connected to the vector network analyzer 31. The resonance of the secondary common mode current can be suppressed.

  The RJ45-SMA conversion board 35 is a multi-pair communication line 23 (for example, STP Ethernet (for example, STP Ethernet) between the coaxial cable connector 34 provided on the copper plate 33 and the communication device 21 to be evaluated. (Registered trademark) cable). Here, the RJ45 connector matched to the Ethernet (registered trademark) cable and the SMA connector matched to the coaxial cable are provided, but a connector matched to the cable to be used can be used. The RJ45-SMA conversion board 35 connects the other two ports of the vector network analyzer 31 to the two communication ports (physical ports # 2 and # 3 in FIG. 4) of the communication device 21, respectively. Six communication ports not used by the communication device 21 are terminated with 50Ω.

  The power supply line 22 connected to the AC power supply port of the communication device 21 to be evaluated is arranged in a straight line at a certain height from the system ground 24 in order to stabilize the transmission characteristics. Here, the communication device 21 and the CDNE 27 are placed on the metal box 36 so that the power line 22 has a constant height h = 100 mm. The many-pair communication line 23 connected to the communication port of the communication device 21 is also arranged in a straight line at a certain height from the system ground 24. Here, the RJ45-SMA conversion board 35 is arranged at a predetermined height so that the many-pair communication line 23 has a constant height.

[Measurement method of interference transfer characteristics]
Next, the interference wave transfer characteristic measurement system shown in FIG. 9 is used to mix interference waves from the AC power supply port of the communication device to be evaluated, pass through the communication device, and be transmitted to the communication port. A method for measuring transfer characteristics and a method for evaluating interference will be described. According to the above measurement system, the scattering matrix (S parameter) between the AC power supply port and the communication port of the communication device 21 can be measured. However, since the measurement result is an S parameter corresponding to the physical port, it is necessary to convert them to an S parameter corresponding to the mixed mode port.

  Since the common mode is dominant in the interference wave mixed from the power supply system, it is considered that only the common mode interference wave is applied to the AC power supply side of the communication device 21 to be evaluated. A physical port for measurement corresponds to a mixed mode port for separation for each propagation mode. Here, two communication ports of the communication device 21 (physical ports # 2 and # 3 in FIG. 4) and A conversion process is required to clarify the relationship between the mixed mode port (differential mode port and common mode port). The 3-port mixed mode S parameter indicating this relationship is expressed by the following equation.

In this equation, an interference wave applied from a common mode port (AC power supply port) on the power supply side of the communication device 21, which is a single-ended port, is transmitted to the differential mode port and the common mode port (communication port) on the communication side. The ratio is indicated by S _DS and S _CS .

  As described above, according to the present embodiment, the measurement of the transmission characteristics of the interference wave mixed from the AC power supply port of the communication device, passing through the inside of the communication device and transmitted to the communication port, and the interference wave Can be evaluated. Therefore, even if the propagation mode and transfer characteristics of the disturbing wave entering the disturbed device are complicated and unclear, according to this embodiment, the propagation mode and transfer characteristics can be easily specified. Elucidation of the occurrence mechanism of communication failure and radio wave interference, and easy determination of which mode to take countermeasures against interference waves.

[First Embodiment]
An evaluation example for a commercially available switching hub will be described. Most switching hubs are mainly two-wire power cables without PE wires. The casing is a metal casing or a plastic casing. Even if the case is a metal case, when it is connected with a UTP cable, it is not connected to the system ground when the case is not connected to the shield of the STP cable. For this reason, it is unclear what kind of influence the interference wave transfer characteristic has.

  A plurality of types of switching hubs are used as the communication device 21 that is an evaluation target of the interference wave transfer characteristic measurement system shown in FIG. 9, and the metal box is set so that the power line is horizontal at a height h = 100 mm from the system ground. 36. As an example, three types of switching hubs (DUT1 to DUT3) were installed to evaluate transfer characteristics.

FIG. 10 shows the measurement result of the transfer characteristic | S _CS |. S _CS S-parameter represents the transfer amount to the primary common mode port of the communication side from common mode port of the power supply side. From the measurement results, common to three of the switching hub DUT1～DUT3, has become _{S CS} is maximized at a frequency of about 100 MHz, it can be seen that about -40dB at around 80 MHz. This means that if an interference wave entering from the power supply side in the common mode has a frequency component of 80 MHz, a component of about 1/100 is transmitted to the communication side in the common mode.

  Here, the immunity test level of the communication port defined in CISPR24 (Non-patent Document 3) is defined as 3V. Therefore, when an interference wave having a frequency component of 80 MHz and an amplitude of about 300 V enters from the power supply side, it is evaluated that a malfunction of the communication port can be assumed. It can also be seen that even different types of switching hubs have approximate transfer characteristics.

FIG. 11 shows the measurement result of the transfer characteristic | S _DS |. The S parameter S _DS represents the amount of transmission from the common mode port on the power supply side to the differential port on the communication side. Compared to the transmission amount | S _CS | to the primary common mode in FIG. 10, the characteristics in the vicinity of 100 MHz are greatly different. In particular, the transmission amount | S _DS | to the differential mode of the switching hubs DUT2 and DUT3 is as large as the transmission amount | S _CS | to the primary common mode, whereas in the switching hub DUT1, the primary amount At the point where the transmission amount | S _CS | to the common mode is maximized, the transmission amount | S _DS | to the differential mode is minimized. Usually, since differential transmission is performed at the communication port, the influence of the interference wave in the differential mode is much larger than the interference wave in the differential mode. In consideration of this, when passing through DUT2 and DUT3, it can be evaluated that a 100 MHz interference wave has a large amount of conversion to be converted to the differential mode, and the influence on the communication port is larger than when passing through DUT1.

  As described above, according to the present embodiment, it is understood that even if the communication device (switching hub) has the same function, the transmission characteristics of the interference wave are different if the type is different. Further, when the communication port of each communication device is connected to another device, it can be quantitatively evaluated that the influence on the communication port of the other device is different.

[Second Embodiment]
In the second embodiment, similarly to the first embodiment, the switching hub (DUT1 to DUT3) is used, and the difference in the height h of the power supply line in the interference wave transfer characteristic measurement system shown in FIG. Evaluate the effect on the transfer characteristics. Since the communication port (RJ45 connector) and power supply terminal of the switched hub are at a height of about 15 mm from the bottom surface of the switching hub, in the first embodiment, the switching hub is at a height of 85 mm from the system ground. is set up.

FIG. 12 shows the measurement results of the transfer characteristics | S _CS | and | S _DS | of the switching hub DUT1. The transfer characteristic | S _CS | when the height h = 0, 100, 200 mm from the system ground of the power supply line of the switching hub DUT1 is changed is shown in FIG. 12A, and the transfer characteristic | S _DS | is shown in FIG. ). Similarly, in FIG. 13, the transfer characteristic of the switching hub DUT 2 _| shows the measurement results, in Figure 14, the transfer characteristic of the switching hub DUT3 _{| | S CS |} and _{| S DS S CS |} and _{| S DS} | measurements Results are shown.

  The switching hubs DUT1 and DUT3 have metal casings. Referring to FIGS. 12 and 14, when the power line height h = 0, that is, when the switching hub is also installed on the system ground, Compared with the case where it is installed at other heights h = 100, 200 mm, the characteristics are greatly different. This is because the parasitic capacitance between the system ground and the metal housing of the switching hub has increased.

  On the other hand, the switching hub DUT2 has a plastic casing, and referring to FIG. 13, even if the height h changes, the transmission characteristics do not change greatly. However, it can be said that the measurement result with the height h = 0 mm is somewhat different from the measurement result with the height h = 100,200 mm.

  From the above results, when the interference wave transfer characteristic measurement system shown in FIG. 9 is used, the transfer characteristic is stabilized by setting the height of the power supply line of the communication device to be evaluated to 100 mm or more from the system ground. It can be seen that it can be measured automatically. In addition, as described above, since communication devices are often installed at a distance from the ground, which is a reference potential, in general homes and general office buildings, the height of the power line of the communication device Is 100 mm or more from the system ground, which is an evaluation simulating an actual installation environment. Furthermore, if the measurement system of the present embodiment is used, it is possible to evaluate the influence on the transmission characteristics of the interference wave due to the difference in the height h of the power supply line of the communication device to be evaluated.

[Third Embodiment]
FIG. 15 shows an interfering wave transfer characteristic measurement system that constitutes a measurement system defined in CISPR 16-2-1 (Non-patent Document 4). In this rule, the height h1 of the communication device 21 to be evaluated is arranged at a height of 100 mm from the system ground 24. This is because the parasitic capacitance between the system ground and the communication device is taken into consideration as described in the second embodiment. The power supply line 22 is connected to the communication device 21 from the CDNE 27 arranged on the system ground with a height of h2 = 30 mm, a length of 1 = 200 mm in the horizontal direction, and a vertical direction therefrom. The other configuration is the same as that of the interference wave transfer characteristic measurement system shown in FIG.

  Usually, when conducting disturbance waves are evaluated, the frequency range is often 9 kHz to 80 MHz. However, when considering the expansion of the frequency range of the interference wave to the high frequency side, the fact that the power supply line is bent in the vertical direction may affect the measurement result of the transfer characteristic. Therefore, in the third embodiment, the measurement system (FIG. 15) compliant with CISPR16-2-1 and the measurement result of the measurement system (FIG. 9) of this embodiment are compared, and the usefulness of this embodiment is compared. explain.

FIG. 16 shows the measurement results of the transfer characteristics | S _CS | and | S _DS | of the switching hub DUT1 according to CISPR 16-2-1. FIG. 16A shows the transfer characteristic | S _CS | when the height h = 100 mm shown in FIG. 12A, and FIG. 16B shows the transfer characteristic shown in FIG. The transfer characteristic | S _CS | when the height h is 100 mm is also shown. Comparing the two, it can be seen that in the switching hub DUT1, a difference of about 3 dB occurs at the frequency at which the transfer characteristic peaks. That is, the measurement result of the measurement system of this embodiment (FIG. 9) fixed with the power line height h = 100 mm is larger.

  In other words, when the measurement system (FIG. 15) based on CISPR16-2-1 is used, the transfer characteristics are underestimated. It is also conceivable that this difference increases due to the difference in the shape of the bent portion of the power supply line. Therefore, when evaluating the conductive interference wave, the measurement system of the present embodiment (FIG. 9) can take measures against the interference wave in anticipation of safety.

[Fourth Embodiment]
In the fourth embodiment, the CDNE housing is grounded to the system ground with sufficiently low impedance. As shown in FIG. 9, in order to arrange the power supply line 22 linearly from the system ground 24 to the height h, it is necessary to install the CDNE 27 at a certain height from the system ground 24. At this time, it is installed on the metal box 36 having high conductivity so as to be grounded with low impedance. The usefulness of this embodiment will be described below.

FIG. 17 shows the measurement results of the transfer characteristics | S _CS | and | S _DS | of the switching hub DUT 1 when the installation conditions of the CDNE are changed. FIG. 17A shows the transmission characteristic | S _CS | when the height h = 100 mm (with grounding) shown in FIG. 12A and when the metal box 36 is changed to a foamed polystyrene box (grounding). None) transfer characteristic | S _CS |. Similarly, FIG. 17 (b), the transfer characteristics when the height h = 100 mm (there ground) shown in FIG. 12 (b) _| a, transfer characteristics of ungrounded _{| | S CS S CS |} and the Show.

  Comparing both, it can be seen that the transfer characteristic is unstable in the vicinity of 30 MHz when there is no grounding. This is due to the parasitic capacitance between the system ground and the CDNE enclosure. Therefore, the measurement system of the present embodiment (FIG. 9) in which CDNE is connected to the system ground with sufficiently low impedance can more accurately evaluate the transfer characteristic of the disturbing wave.

[Summary]
According to the present embodiment, it is possible to stably evaluate the transmission characteristics of the interference wave mixed from the power line of the communication apparatus, passing through the inside of the communication apparatus, and transmitted to the communication line with good reproducibility. In particular, by defining the physical port (AC power supply port, communication port) of the communication device and the mixed mode port (differential mode, primary common mode, secondary common mode) for separating each propagation mode of the interference wave Since it is possible to evaluate each propagation mode of each port, it is easy to determine which countermeasure is to be taken against which interference wave of which propagation mode of which port.

  In evaluating the transmission characteristics of the interference wave, most of the return current in the primary common mode flows through the shield of the STP cable by using the STP cable on the communication side. For this reason, not only the definition of the primary common mode of the communication port is facilitated, but also a method for fixing (determining) the termination impedance between the shield and the communication line is facilitated. If a UTP cable is used, the return current of the primary common mode flows to another pair line, so it is necessary to newly define the termination condition between the two wires to be evaluated and the other pair line. Evaluation is complicated.

  When connecting a communication line (one pair) and a coaxial cable on the communication side of the communication device to be evaluated, a coaxial connector is installed on a highly conductive metal plate (copper plate) to shield the coaxial cable or the like. Is connected to the system ground with low impedance. Thereby, propagation of the secondary common mode to the coaxial cable or the like connected to the vector network analyzer can be prevented, and the transfer characteristics can be stably measured. Moreover, the same effect can be acquired by attaching an absorption clamp to the coaxial cable on the power source side. With such a configuration, it is possible to eliminate the influence of the resonance phenomenon caused by the secondary common mode current flowing through each coaxial cable or the like.

  The height h of the power supply line of the communication device to be evaluated is 100 mm or more from the reference system ground, and the communication line is also arranged in a straight line so that the communication line has the same height. According to this configuration, the influence of the parasitic capacitance generated between the communication device to be evaluated and the system ground and between the power supply line and the communication line and the system ground can be removed as much as possible. In addition, as described above, communication devices are often installed at a distance from the ground, which is a reference potential, in general homes, general office buildings, etc., and therefore, an evaluation that simulates an actual installation environment Is possible.

  As for the case of the disturbance wave application circuit (CDNE), by grounding it with a sufficiently low impedance from the system ground, the resonance phenomenon caused by the parasitic capacitance between the system ground and the CDNE case can be removed. Wave transfer characteristics can be evaluated more accurately.

DESCRIPTION OF SYMBOLS 1 Interfered device 2,11,21 Communication apparatus 3 Distribution board 4 Inverter / converter 5 Power supply line 6,13,23 Many-pair communication line 12,22 AC power supply line 14,24 System ground 15 AC power supply port 16 Communication port 17 , 27 CDNE
18 Outlet 31 Vector Network Analyzer 32 Absorption Clamp 33 Copper Plate 34 Coaxial Cable Connector 35 RJ45-SMA Conversion Board 36, 37, 38 Metal Box

Claims (8)

In a communication device in which a power supply line for receiving power supply and a communication line for communication with another device are connected, the communication line is mixed from the power supply line and passes through the communication device. A method for measuring a disturbance wave transmission characteristic for evaluating a transmission characteristic of a disturbance wave transmitted to
Defining a power port on the power line side and a communication port on the communication line side as physical ports for measurement in the communication device;
Defining a mixed mode port for separating and measuring the transmission characteristics for each interference wave propagation mode including a differential mode, a first common mode, and a second common mode; and an S parameter corresponding to the physical port A transmission characteristic for each propagation mode, and an interference wave transfer characteristic measurement method, comprising: converting S into a S parameter corresponding to the mixed mode port;   The communication line is a shielded twisted pair wire, and a termination impedance between the shield and the communication line is defined on the assumption that a return current of the primary common mode flows through the shield. The interference wave transfer characteristic measuring method according to claim 1. The communication line is an unshielded twisted pair wire, and assuming that the return current of the primary common mode flows through the other communication line, a termination impedance between the communication line and the other communication line is set. The interference wave transfer characteristic measuring method according to claim 1, wherein the interference wave transfer characteristic measuring method is defined. In a communication device in which a power supply line for receiving power supply and a communication line for communication with another device are connected, the communication line is mixed from the power supply line and passes through the communication device. A disturbance wave characteristic measurement system for evaluating the transfer characteristic of a disturbance wave transmitted to
A first port connected to the power supply line of the communication device, and a vector network analyzer and a second and third port connected to said communication line,
An absorption clamp inserted into a coaxial cable connecting the power line and the first port;
An interference comprising: a shield for a coaxial cable connecting the communication line and the second port, the communication line and the third port, and a grounding means for connecting the system ground with a low impedance; Wave transfer characteristic measurement system. An interference wave applying circuit inserted between the power cable and a coaxial cable connecting the first port;
5. The interference wave transfer characteristic measurement system according to claim 4, wherein the power line between the interference wave application circuit and the communication device is linearly arranged at a certain height from the system ground. 6. .   6. The interference wave transfer characteristic measurement system according to claim 5, wherein the interference wave application circuit is connected to the system ground with a low impedance.   The interference wave transfer characteristic measuring system according to claim 5 or 6, wherein the certain height is 100 mm or more. It said grounding means, said a conductive metal plate the connector is installed coaxial cable is connected, by connecting the metal plate to the system ground, the shield and the system ground of the coaxial cable The interference wave transfer characteristic measuring system according to any one of claims 4 to 7, characterized by being connected with low impedance.