JP3355597B2 - Interference wave applying device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of applying a disturbance wave to a communication device in order to measure the resistance of the communication device to a conducted disturbance wave entering the communication device via a communication line. Related to the device. In particular, the present invention relates to an interference wave applying device that can be used in a frequency band of 15 Hz to 10 kHz.

[0002]

2. Description of the Related Art Interference waves entering a communication device via a communication line cause a malfunction of the communication device. Therefore,
In order to realize highly reliable communication, it is necessary to clarify the tolerance of the communication device. The target value and test method for the proof stress of the communication equipment are recommended by the international standardization organization (for example, IEC1000-4-6).

In order to measure the resistance of a communication device to an interference wave, a method of inserting an interference wave applying device between a communication line terminal and a communication line of the communication device and artificially applying the interference wave to the communication device is known. Be taken. 2. Description of the Related Art Conventionally, proof tests against conducted disturbance waves are mainly performed in a frequency band of 150 kHz to 80 MHz. However, low frequency interference such as power supply harmonics may affect electronic equipment.
The proof stress test method at kHz is also studied by the international standardization organization (for example, IEC1000-4-16).

FIG. 9 shows a circuit configuration of a conventional interference wave applying device. In the figure, reference numeral 1 denotes a communication device to be measured, 2 denotes an auxiliary device for operating the communication device to be measured 1 and simultaneously testing whether or not the communication device to be measured 1 is operating normally;
Is an interfering wave generator for generating an interfering wave applied to the communication device under test 1, and 40 is connected between the device under test 1 and the auxiliary device 2 to measure the interfering wave input from the interfering wave generator 3. This is an interference wave applying device applied to the communication device 1.

[0005] The interference wave applying device 40 is a communication device under test 1.
EUT port 4 connected to AE, AE connected to auxiliary equipment 2
Port 5, an input port 6 connected to the interference wave generator 3, a capacitor 7 for preventing a DC voltage based on a supply voltage on a communication line from flowing into the input port 6, a resistor for adjusting the common mode impedance of the circuit 8. The transformer 9 which has little impedance to the common mode current flowing between the communication line and the ground, but has a large impedance to the signal current flowing through the communication line, and prevents the leakage of interference waves to the auxiliary equipment 2. Common mode choke coil 10
It is composed of The common mode choke coil 10 is used in the case of a communication line because it is necessary to pass a DC power supply current and a communication signal simultaneously, but in the case of a power supply line, an insulating transformer or the like is used.

[0006]

In order to use a conventional disturbing wave applying apparatus as shown in FIG. 9 in a frequency band of 15 Hz to 150 kHz, the impedance between the EUT port 4 and the ground (common mode impedance) is independent of the frequency. )
Must be 150Ω ± 20Ω. Assuming that the output impedance of the interference wave generator 3 is 50Ω, the value of the resistor 8 connected in parallel needs to be 100Ω. Therefore, the resistor 8
Is a normal resistor, and the resistance value R is R = 100 × n (1) where n is the number of core wires. That is, if the number of core wires is 2, R = 200
Ω.

Next, it is necessary to set the capacitor 7 connected to the resistor 8 so as not to affect the common mode impedance. The maximum common mode impedance when the resistor 8 and the capacitor 7 are connected in series is at 15 Hz. At this time, the resistor 8
And the total impedance of the capacitor 7 must be equal to or less than 120 Ω after subtracting the output impedance 50 Ω of the interference wave generator 3. The capacitance value C of the capacitor 7 is C> 1 / [nω ｛120 ² − (R / n ) ² ｝ ^1/2 ] ... It is necessary to satisfy the relationship of (2). Here, when n = 2,
It is necessary to use a capacitor 7 of 80 μF or more.

The insertion loss of the interference wave applying device 40 is as follows:
It must be small to guarantee the normal operation of the communication device under test 1. This insertion loss can be calculated from the equivalent circuit shown in FIG. In FIG. 10, a communication device under test 1, a capacitor (C) 7, a resistor (R)
8, the transformer (L) 9 corresponds to each unit shown in FIG.
The characteristic impedance of the line and Z _0. Than this, the insertion loss Loss is, Loss = 20 log | 1 + Z 0/2 (R + jωL + 1 / jωC) | ... can be expressed as (3). Here, the characteristic impedance Z ₀
Is 600Ω, the inductance L for the signal current of the transformer 9 must be 8H or more when C is 80 μF so that the insertion loss Loss becomes 2 dB (15 Hz) or less, and a large inductance is required. .

On the other hand, the common mode choke coil 10
Sets the common mode impedance to 150 Hz at 15 Hz to 10 kHz.
In order to make ± 20Ω, it is necessary to be 1.4-2.4H. In order to realize such a common mode choke coil, it is necessary to wind many windings on a magnetic material having high magnetic permeability. However, it is difficult to realize such a common mode choke coil that can pass a digital signal exceeding 1 MHz.

[0010] Due to such a situation, an effective interference wave applying circuit in a frequency band of 15 Hz to 10 kHz has not been realized by using a technique for designing an interference wave applying circuit of 150 kHz or more. The present invention provides an interference wave applying device that can efficiently apply an interference wave of 15 Hz to 10 kHz to a communication device to be measured, has a stable common mode impedance, and can suppress leakage of the interference wave to auxiliary devices. The purpose is to:

[0011]

In order to solve the conventional problems, it is important to isolate the EUT port 4 and the AE port 5 with respect to common mode signals. The interference wave applying apparatus of the present invention realizes this. FIG. 1 shows a basic configuration of an interference wave applying apparatus according to the present invention. Parts corresponding to the respective parts of the interference wave applying device 40 shown in FIG. 9 are denoted by the same reference numerals.

In FIG. 1, an EUT port 4, an AE port 5, an input port 6, a capacitor 7, a resistor 8, and a common mode choke coil 10 perform the same functions as in the prior art. Between the EUT port 4 to which the communication device to be connected is connected and the AE port 5 to which the auxiliary device is connected, a transformer 12 for applying an interference wave voltage having little loss to the communication signal is connected. A bypass capacitor 11 having almost no loss with respect to a communication signal and an interfering wave is inserted at an electrical middle point of the winding on the AE port 5 side of the transformer 12. A capacitor in which two capacitors 7 having the same capacitance value are connected in series is inserted into an electrical middle point of the winding on the EUT port 4 side of the transformer 12. Between the middle of these two capacitors 7 and the input port 6 to which the interfering wave generator is connected, an interfering wave is generated as an input impedance between a virtual middle point of the communication line viewed from the communication device under test and the ground. The value including the internal impedance of the vessel is 150 in the frequency band of 15Hz to 10kHz.
A resistor 8 having a resistance of ± 20Ω is connected. Transformer 1
The impedance between the windings on the AE port 5 side and the EUT port 4 side at the center is 15 Hz.
A common mode choke coil 10, which is equal to or larger than Ω and passes a DC current based on a supply voltage on a communication line between the EUT port 4 and the AE port 5, is connected via a cable 13.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 2 shows a first embodiment of an interference wave applying apparatus according to the present invention. This embodiment corresponds to a pair of balance lines. In the figure, 1 is a communication device to be measured, 2 is an auxiliary device, 3 is an interference wave generator, and FIG.
Is similar to the conventional configuration shown in FIG. Reference numeral 41 denotes an interference wave applying device according to the present invention, which corresponds to the basic configuration shown in FIG. However, in the present embodiment, the transformer 12
As the bypass capacitor 11 inserted into the electrical middle point of the winding on the side of the AE port 5, a capacitor in which two capacitors having the same capacitance value are connected in series is used, and the middle point is grounded. With such a configuration, the isolation characteristics between the application point of the interference wave and the auxiliary device 2 can be further improved.

Next, the operation of this embodiment will be described. While transmitting a communication signal between the EUT port 4 and the AE port 5, the disturbance wave voltage for the immunity test generated by the disturbance wave generator 3 is supplied to the input port 6. This disturbing wave voltage is applied to the EUT port 4 via the resistor 8. On the other hand, this disturbance wave voltage is not applied to the AE port 5 side by the common mode choke coil 10.
Therefore, a test in which an interference wave voltage is applied only to the communication device under test 1 can be performed.

The communication signal propagates through the two transformers 12, and the direct current for power supply flows through the cable 13 connected between the midpoints of the transformers 12 and the common mode choke coil 10. As the transformer 12, a transformer that can pass a communication signal having a high frequency of about 1 MHz can be easily realized. In this embodiment, the band is 10 Hz to
A 20 MHz video transformer is used. With this, ISD
It is also possible to test communication devices that process high-speed communication signals, such as N communication devices.

The impedance of the common mode choke coil 10 becomes minimum when the frequency is 15 Hz. At this time, the common mode impedance of the interference wave applying device 41 is 150 ± 20Ω.
, The impedance of the common mode choke coil 10 needs to be 381Ω or more. However,
Since the common mode choke coil 10 does not need to flow any DC current, a multi-winding coil using a core having a high magnetic permeability can be used, so that a coil having an impedance of 381Ω or more at 15 Hz can be easily realized. In the present embodiment, 15
The impedance of 2810Ω at Hz is used.

FIG. 3 shows a measurement result of the common mode impedance when the AE port is opened in the present embodiment. FIG. 4 shows a measurement result of the common mode impedance when the AE port is short-circuited in the present embodiment. 3 and 4, the horizontal axis represents the frequency (kHz), and the vertical axis represents the absolute value (Ω) and the phase angle (degree) of the common mode impedance. In the present embodiment, A
Regardless of whether the E port is open or short circuit, the absolute value of the common mode impedance is in the frequency band of 100Hz to 10kHz.
It can be seen that it is within the range of 150 ± 20Ω. In addition,
In this figure, only the values up to 100 Hz are shown, but the characteristics near this frequency are stable, and this relationship is considered to hold in the transformer frequency band (10 Hz or more). However, it is clear that it falls within the range of 150 ± 20Ω.

FIG. 5 shows a measurement result of the coupling coefficient from the input port to the EUT port in the present embodiment. In the figure, the horizontal axis is frequency (kHz) and the vertical axis is coupling coefficient (dB). In this embodiment, the coupling coefficient is 10 Hz to 10 k.
It is 1 dB or less in Hz, which indicates that the interference wave is efficiently applied to the EUT port. FIG. 6 shows a measurement result of the decoupling coefficient from the input port to the AE port in the present embodiment. In the figure, the horizontal axis is frequency (kHz) and the vertical axis is decoupling coefficient (dB). In the present embodiment, the decoupling coefficient is 30 dB or more at 10 Hz to 10 kHz, and it can be seen that the leakage of the interference wave to the AE port is sufficiently small.

FIG. 7 shows one of the interference wave applying devices of the present embodiment.
The measurement results of the insertion loss in a 10Ω system are shown. In the figure, the horizontal axis is frequency (kHz) and the vertical axis is insertion loss (dB). In the present embodiment, the insertion loss is 2 dB or less at 20 Hz to 5 MHz, and it is understood that the condition for operating the communication device under test using a wide frequency band normally is satisfied.

(Second Embodiment) FIG. 8 shows a second embodiment of the interference wave applying apparatus according to the present invention. The present embodiment corresponds to two pairs of balance lines. In the figure,
1 'is a communication device to be measured corresponding to 4-wire, 2' is an auxiliary device corresponding to 4-wire, and 3 is an interference wave generator. The interference wave applying device 42 of the present embodiment has a configuration in which two two-wire interference wave applying devices 41 of the first embodiment are combined. Some 4-wire communication devices use not only the propagation of communication signals using two pairs of communication lines but also the virtual intermediate point of each pair as a transmission path. A transformer 14 connecting each intermediate point of the two capacitors 7 and 11 is used to pass such a transmission signal. The disturbance voltage input from the disturbance generator 3 via the resistor 8 is applied to each balanced line via the transformer 14.

With such a circuit configuration, it is possible to test a communication device having a four-wire communication line terminal such as ISDN. By the same procedure, it is possible to realize an interference wave applying device for 2n (n is a natural number) communication lines.

[0022]

As described above, the interference wave applying apparatus according to the present invention is stable in the frequency band of 15 Hz to 10 kHz which has been difficult to measure when measuring the resistance of the communication equipment to be measured to the conducted interference waves. Can be applied. Further, the interference wave applying apparatus of the present invention can be easily applied to a case where the number of logarithms is increased to one pair or two pairs.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a basic configuration of an interference wave applying apparatus according to the present invention.

FIG. 2 is a circuit diagram showing a first embodiment of an interference wave applying apparatus according to the present invention.

FIG. 3 is a diagram showing a measurement result of a common mode impedance when an AE port is opened in the first embodiment.

FIG. 4 is a diagram showing a measurement result of a common mode impedance when the AE port is short-circuited in the first embodiment.

FIG. 5 is a diagram showing measurement results of a coupling coefficient according to the first embodiment.

FIG. 6 is a view showing a measurement result of a decoupling coefficient in the first embodiment.

FIG. 7 is a diagram showing a measurement result of insertion loss in the first embodiment.

FIG. 8 is a circuit diagram showing a second embodiment of the interference wave applying apparatus according to the present invention.

FIG. 9 is a circuit diagram showing a configuration of a conventional interference wave applying device.

FIG. 10 is a diagram showing an equivalent circuit for calculating an insertion loss of a conventional interference wave applying device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Communication equipment under test 2 Auxiliary equipment 3 Interference wave generator 4 EUT port 5 AE port 6 Input port 7 Capacitor 8 Resistor 9 Transformer 10 Common mode choke coil 11 Capacitor for bypass 12 Transformer 13 Cable 14 Transformer 40, 41, 42 Disturbance Wave application device

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04B 17/00

Claims (1)

(57) [Claims] 1. A communication line terminal of a communication device under test that uses a balanced line as a communication line, and an auxiliary device connected to the communication line terminal to check operation of the communication device under test, In an interfering wave applying apparatus for applying an interfering wave from a disturbing wave generator to a communication line terminal of the communication device to be measured and a ground, almost no loss is caused for a communication signal between the communication device to be measured and the auxiliary device. A transformer that has little loss with respect to the communication signal and the interfering wave at an electrical midpoint of the auxiliary device-side winding of the transformer, At the electrical midpoint of the winding on the device side, insert a capacitor connected in series with two capacitors of the same capacitance value, between the middle of the two capacitors connected in series and the interfering wave generator, The measured As the input impedance between the virtual middle point of the communication line and the ground as viewed from the equipment, connect an impedance such that the value including the internal impedance of the disturbance generator is 150 ± 20Ω in the frequency band of 15Hz to 10kHz. A common mode choke coil having an impedance of 381Ω or more with respect to 15 Hz is connected between the electrical midpoints of the respective windings of the transformer on the auxiliary device side and the communication device side under test, and A disturbing wave applying apparatus, wherein the disturbing wave is applied to the communication device under test via the impedance.