JPH0951292A - Deciding method for presence or absence of failure in balanced paired line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acceptance discrimination method in which a broken balanced pair line is simply detected. SOLUTION: A DC capacity and an AC capacity are obtained from a state (normal) connecting to a terminal equipment and a state (broken) not connecting to the terminal equipment are obtained by changing the length of balanced pair lines in advance and a threshold line consisting of line segments or a curve to separate the normal area from the broken line area is obtained on a graph representing the correlation of both the capacity sets, the actual managements and the threshold line are compared so as to decide whether or not the terminal equipment is connected to the balanced pair line (priority of line). Let the threshold line passing through the origin and separating the normal area and the broken line area be a line segment, then the gradient of the line is compared with a ratio of the actual measurements of both the capacities to decide the propriety of the line. Furthermore, a threshold line is set to distinguish the DC capacity from the AC capacity and the difference of the measurements between both the capacities is compared with the threshold line to decide the propriety of the line.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining the quality of a balanced pair line (determining the presence / absence of a failure) from a remote location, and particularly to a terminal device connected to the end of a general subscriber telephone line. The present invention relates to a method for determining whether or not a balanced pair line has a disconnection failure by utilizing the electrical characteristics of.

[0002]

2. Description of the Related Art Conventionally, the determination of the quality of a communication line has been carried out as an indispensable factor for maintaining a communication line. Generally, when a communication line subscriber reports a failure, the telephone company diagnoses by remote test whether or not the balanced pair line is normal, and if it is difficult to determine whether the balanced pair line is abnormal or not, the repair person is on site. Are dispatched to investigate the cause of failure and repair it.

In this case, the quality of the balanced pair line means that there is no failure, and that there is a failure, and the failures can be classified into insulation failure system failures and disconnection system failures. The conventional methods for determining the disconnection failure of the balanced pair line for communication include a capacity measuring method, a determining method using a terminal device with a separating function, and a pulse measuring method. Next, these methods will be described.

In the capacity measuring method, as shown in the judgment procedure in FIG. 14, the capacity between lines forming a balanced pair line is measured (s1), and the value is compared with a standard value used for judgment (s).
2) If it is equal to or more than the standard value, it is judged as a good wire (s3), and if it is smaller, it is judged as a disconnection (s4). When making a pass / fail judgment, if some terminal devices currently on the market do not have a capacity and the judgment accuracy is affected, use a modular jack provided at the end of the balanced pair line on the subscriber side. The capacity is measured by changing to a modular jack with a capacitor that has a built-in series circuit consisting of a 100 kΩ resistor and a 0.27 μF capacitor.

The determination method by the terminal device with the separation function is
This is a method of making a judgment by using a divider installed in the protector attached to the demarcation point between the telephone company equipment and the terminal side and having a remote dividing test function. As shown in FIG. 15, the determination procedure is as follows. The tester sends a current for operating the switch (s1), the switch shorts the lines (s2), and sends the measured current to perform a loop test. Do (s
3) The test result is confirmed (s4), and it is determined whether it is a good wire (s5) or a failure (s6) based on the test result. After that, a current for releasing the operation of the switch is sent to release the short circuit between the lines (s7).

In the pulse measurement method, as shown in the determination procedure in FIG. 16, a narrow pulse is sent from one end of the balanced pair line to be diagnosed (s1), and the reflected waveform is detected ( s2), observing this waveform with a cathode ray tube (s3),
Depending on whether the waveform is normal (s4), if it is normal, it is judged as a good line (s5), and if not normal, it is judged as a failure (s6).
The type and position of the failure are determined from the amount of attenuation of the reflected pulse and the time required for the reflection (s7).

FIG. 17 shows an example of a pulse waveform measured by the pulse measuring method. The waveform in FIG. 17 (a) is a measurement of a faulty line of which both wires of the balanced pair line are broken at the 1 km point. The peak on the left side of the curve in the figure is the waveform of the transmitted pulse, and then it smoothly descends and changes greatly at the center. The change in the central portion indicates a failure, and the swelling of the waveform indicates a disconnection system failure, and the starting point of the change indicates the failure position.

The waveform of FIG. 17 (b) is a measurement of a faulty line with poor insulation in which the two cores of the balanced pair line are short-circuited at a 1 km point. Unlike Figure (a), the fact that the waveform indicating a failure is downward indicates that the failure is due to an insulation failure, and the starting point of the change indicates the failure location.

[0009]

However, each of the above-mentioned three conventional methods has the following drawbacks. That is, in the capacitance measuring method, a person in charge of the test makes a judgment by looking at the measured value, so that it takes a long time from the measurement to the end of the judgment. Further, when the capacity of the terminal device is only the modular jack with a capacitor, the measured values of the good line and the defective line are close to each other depending on the distance to the terminal device, which makes the determination difficult.

In addition, in the determination method by the terminal device with the separating function, it is necessary to install the separating device in advance, which requires a lot of manpower and expense. Also,
When making a judgment, it is necessary to confirm the presence or absence of a discriminator, and it takes time and manpower to investigate the equipment data.
Furthermore, the quality can be judged only up to the protector at the equipment demarcation point,
It is not possible to judge the state from there to the terminal equipment.

Further, in the pulse measurement method, data of measurement conditions are required when setting and operating the apparatus for measurement, and it takes time and manpower to investigate equipment data for obtaining the data. Further, since the measurement result is obtained as a pulse waveform as shown in FIG. 16, the person in charge of testing needs to have a high level of knowledge and skill in order to make a determination based on this. An object of the present invention is to eliminate the above-mentioned problems and provide a pass / fail judgment method capable of easily detecting a disconnection failure of a balanced pair line.

[0012]

In order to achieve the above object, the present invention incorporates a series circuit composed of a resistor and a capacitor by measuring the capacitance between a balanced pair line to be diagnosed with direct current and alternating current. It is determined whether or not the terminal equipment is connected to the balanced pair line, and then whether or not the wire is disconnected.

In the present invention, the length of the balanced pair line is sequentially changed in advance, and the terminal device is connected to the end of this line (normal state) and not connected (disconnected state).
Regarding the DC capacity and the AC capacity at a predetermined frequency by calculation or experiment for the above, on the graph showing the correlation between these two capacities, the threshold line ε consisting of a straight line or a curve separating the normal area and the disconnection area is obtained, Actual measured value and this ε
And is compared to determine whether the terminal device is connected to the balanced pair line.

In another aspect of the present invention, the length of the balanced pair line is sequentially changed in advance, and calculation or calculation is performed for a state in which the terminal equipment is connected to the end of this line (normal state) and a state in which it is not connected (disconnection state). Obtain the direct current capacity and the alternating current capacity at a predetermined frequency by an experiment, on a graph showing the correlation between these two capacities, obtain a straight line that separates the normal region and the disconnection region through the origin, and further obtain the inclination θ of this straight line. By comparing the actual measured value with this θ, it is determined whether or not the terminal device is connected to the balanced pair line.

In still another aspect of the present invention, the frequency at which the AC capacity linearly increases with an increase in the distance to the terminal equipment of the balanced pair line is selected in advance by calculation or experiment,
In addition, by changing the length of the balanced pair line in sequence, the DC capacity and the AC capacity at the above-mentioned selected frequency for the state where the terminal equipment is connected to this terminal (normal state) and the state where it is not connected (disconnection state) Then, a threshold value δ having a value less than or equal to the difference value between these two capacities is set, and the difference value between the actual measured values of both capacities is compared with this δ, and the terminal device is connected to the balanced pair line. Is determined.

The present invention as described above utilizes the fact that the capacity measured by direct current and the capacity measured by alternating current have different values depending on whether the terminal device is connected or not, and the disconnection failure of the target line is utilized. It was made based on the finding that it is possible to easily determine the presence or absence of.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a state in which a terminal device having an impedance Z _t is connected to the end of a cable having a length l. In this case, the input admittance Y _in measured from the starting ends L ₁ and L ₂ by AC is Y _in = (Z _t · cosh γl + Z ₀ ) / Z ₀ (Z _t + Z ₀ · cosh γl) (1). Here, Z ₀ is the characteristic impedance of the cable, and γ is the propagation constant of the cable.

When the calculation result of the equation (1) is organized and divided into a real number part and an imaginary number part, it can be expressed as Y _in = C _AC + jωC _AC (2). Where ω is the angular frequency. On the other hand, in FIG. 1, the capacitance measured by direct current from the starting ends L ₁ and L ₂ is C _DC .

[0019]

[Embodiment] Next, a first embodiment of a method for determining a disconnection fault of a balanced pair line according to this example will be described. FIG. 2 is a diagram showing a schematic procedure. First, by changing the length of the balanced pair line in sequence, the DC capacity and the predetermined frequency are calculated or calculated for the state where the terminal equipment is connected to this terminal (normal state) and the state where it is not connected (disconnection state). The alternating current capacity is calculated, and the threshold line ε that separates the normal area and the disconnection area is calculated on the graph showing the correlation between these two capacities (sa).

FIGS. 3 to 7 are graphs showing the results of simulation performed on the configuration of FIG. These figures show the values when changing the cable length from 0 to 7 km and changing from 10 Hz to 100 kHz in each figure. The vertical axis of the figure represents C _AC and the horizontal axis represents C _DC . In each figure, a curve showing the correlation between both capacities for a good line and a correlation between both capacities for a broken fault line are shown. A curve is shown, and if possible, a range in which a threshold line can be set that divides the area containing both curves.

FIG. 3 shows values calculated assuming that the AC frequency is 10 Hz. Capacitance values of a good line and a broken fault line are parallel to each other and become a locus close to a straight line, and both regions can be separated by setting a threshold line in a hatched range. FIG. 4 shows values calculated assuming that the frequency of the alternating current is 100 Hz, and the threshold line can be set almost in the same manner as in the case of FIG.

FIG. 5 shows values calculated assuming that the frequency of the alternating current is 1 kHz. Capacitance values of a good line and a broken fault line are parallel to each other and draw a parabolic trajectory to the right, and as the fault position becomes farther away, the fault line value gradually approaches the trajectory of the good line value, but is shown as a diagonal line. A threshold line can be set for the range. 6 and 7 are the values calculated assuming that the AC frequencies are 10 kHz and 100 kHz, respectively. In both cases, the loci of the capacitance values of the good line and the broken fault line intersect, and the threshold line cannot be set.

Therefore, in the present invention, it is not appropriate to use the frequency range of 10 kHz or higher.
FIG. 8 shows an example of setting the threshold line when the alternating current frequency is 1 kHz. The left side of the threshold line ε is the disconnection failure region, and the right side is the normal region.

Returning to the procedure of FIG. 2 again, the capacitance between the lines to be diagnosed is measured by the direct current and the alternating current at the frequency used in step sa (sb). It is determined whether the correlation point between the measured DC capacity C _DC and the AC capacity C _AC is on the DC capacity side with respect to the threshold line ε obtained in step sa (sc), and the terminal is connected to the balanced pair line. It is determined whether or not the device is connected (sd, se), and from the result it is determined whether the balanced pair line is normal or the disconnection fault (sf, se).
sg).

Next, a second embodiment of the method of the present invention will be described. FIG. 9 is a diagram showing a schematic procedure of the quality judgment method of the balanced pair line which is the second embodiment and is judged by using the inclination θ of the threshold line as a threshold value. In this example, FIG.
As shown in 0, on the graph showing the correlation between the same DC capacity C _DC and AC capacity C _AC created in the first embodiment,
The threshold line is defined as a straight line ε passing through the origin, and the slope θ of the straight line representing the ratio of the _AC capacity C _{AC to} the DC capacity C _DC is obtained and set as the threshold value (sh). Next, the capacitance value between the lines to be diagnosed is measured by direct current and alternating current of the same frequency used in step sh (si).

The ratio of the measured AC capacity C _{AC to} the DC capacity C _{DC is} calculated (sj), and the value of this ratio is compared with the threshold value θ calculated in step sh (sk). When it is small, the terminal device is connected (sl), and the line is judged to be normal (sn). On the other hand, when the measured ratio is θ or more, the terminal device is not connected (sm) and the line is disconnected. It is judged as a failure (so).

According to this method, the slope θ has a constant value, and it is only necessary to compare the slope θ and the ratio C _AC / C _DC of the _AC capacity C _{AC to} the DC capacity C _DC obtained from the measured value. Since it is possible to judge the quality of the balanced pair line, it is extremely practical.

Next, a third embodiment of the method of the present invention will be described. FIG. 11 is a diagram showing a schematic procedure for a quality judgment method of a balanced pair line in which a judgment is made using the magnitude of the difference between the value of the DC capacity C _{DC and} the value of the AC capacity C _AC as a threshold value.
First, by calculation or experiment, a frequency at which the AC capacity increases linearly with an increase in the distance l to the terminal device is selected (sp).

Next, the length of the balanced pair line is sequentially changed, and the terminal equipment is connected to the end of this line (normal state).
For the unconnected state (disconnected state), the DC capacity and the AC capacity at the frequency selected in step sp are obtained by calculation or experiment, and the difference between the two capacities is further obtained. Set δ (sq).

This procedure will be described in detail with reference to FIGS. 12 and 13. The graphs in these figures use a balanced cable with a conductor system containing 50 pairs of 0.4mm diameter conductors,
The values obtained by simulation are shown for the direct current capacity and alternating current capacity between each pair of wires in the case where a communication line of up to 6 km is made longer by 1 km and a terminal device is attached to the end. The vertical axis represents the capacitance value, and the horizontal axis represents the distance from the starting point of the cable to the position of the terminal device. FIG. 12 shows the case where the AC frequency is 10 Hz, and FIG. 13 shows the case where the AC frequency is 10 kHz.

In the case of FIG. 12, it can be seen that both the direct current capacity C _DC and the alternating current capacity C _{AC of} both the good wire and the broken wire are increased with an increase in the distance to the terminal equipment and are represented by almost a linear function. Also, the capacity C per unit length of cable is about 5
Since it is 0 nF / km, it can be seen that the _AC capacity C _AC can be expressed by C _AC = C × L (3). Further, when comparing the DC capacity and the AC capacity of the good wire, it can be seen that their values show a substantially constant difference irrespective of the position of the terminal device, but there is almost no difference between the broken wire and the broken wire. .

On the other hand, in the case of FIG. 13, the AC capacity C _AC is
Both the good wire and the broken wire are not increasing with the increase in the distance to the terminal equipment. Further, when the DC capacity C _DC and the AC capacity C _AC are compared, it can be seen that the difference between the two is not constant for both the good wire and the broken wire, and there is a difference depending on the distance to the terminal device. .

Therefore, both the direct current capacity and the alternating current capacity increase with an increase in the distance to the terminal equipment, and a frequency range almost represented by a linear function, for example, a frequency such as 10 Hz illustrated in FIG. (3) can be satisfied by choosing. In this case, since the DC capacity C _DC can be expressed as C _DC = (C × L) + C _T (4), C _T can be calculated from the formulas (3) and (4) as C _T = C _DC −C _{Represented by AC} (5).

From these facts, if the value of the difference C _T between the two capacities corresponding to the capacity of the terminal equipment is C _T ≦ 0 in the frequency range satisfying the equation (3), the disconnection fault, C _T > 0. If so, it can be judged to be normal. However, when the value of the difference C _T is obtained from the equation (5), an error occurs due to the measurement conditions or the like. Further, the equation (3) is also almost satisfied in the selected frequency range, and is not strictly C _AC = C × L.

Therefore, as shown in FIG.
C) when the container is connected)_DCAnd C_ACDifference value from
Set the threshold value δ with a value less than (capacity of terminal device)
Then C _TIs greater than δ, it is a good line, C_TIs less than or equal to δ
Make a judgment of disconnection failure. Taking the case of FIG. 12 as an example
If so, set the threshold value δ within the range of 50 to 100 μF.
do it. Thus, in setting the threshold δ
More accurately, it is possible to judge whether the circuit is broken or not.
Can be.

Returning again to the procedure shown in FIG.
The capacity between the lines to be diagnosed is measured by the direct current and the alternating current of the frequency used in step sq (sr), and the difference C _T between the measured value of the direct current capacity C _{DC and} the value of the alternating current capacity C _AC is obtained (s
s). Next, the difference C _T obtained in step ss and the threshold δ obtained in step sq are compared (st), and when C _T is larger than δ, it is determined that there is a terminal device at the end of the balanced pair line (su), It is judged that the balanced pair line is normal (sw), while when C _T is δ or less, it is judged that there is no terminal device at the end of the balanced pair line (sv), and it is judged that the balanced pair line is disconnected (s).
x).

[0037]

As described in detail above, according to the method of the present invention, the capacitance value of the terminal equipment and the threshold value ε or the threshold value θ obtained by the measurement of the balanced pair line which is the object of the quality judgment. Or by using the value of threshold δ,
The presence / absence of a terminal device connected to the end of the balanced pair line that is the target of determination can be determined to determine whether or not there is a disconnection failure in the balanced pair line, which can be expected to improve the judgment capability and shorten the manual operation time. , It is possible to judge whether or not there is a disconnection failure of the balanced pair line from a remote place with an extremely low error rate. Thereby, it becomes possible to efficiently perform the disconnection failure diagnosis of the balanced pair line and the communication line accommodating the balanced pair line.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a balanced pair line.

FIG. 2 is a diagram showing a schematic procedure of a first embodiment of the method of the present invention.

FIG. 3 is a graph showing a result of simulation performed on the first embodiment.

FIG. 4 is a graph showing a result of simulation performed on the first embodiment.

FIG. 5 is a graph showing a result of simulation performed on the first embodiment.

FIG. 6 is a graph showing the result of simulation performed on the first embodiment.

FIG. 7 is a graph showing a result of simulation performed on the first embodiment.

FIG. 8 is a diagram showing an example of setting a threshold line in a correlation diagram between a DC capacitance value and an AC capacitance value.

FIG. 9 shows a schematic procedure of a second embodiment of the method of the present invention.

FIG. 10 is a diagram showing an example in which the inclination θ of a threshold line of a straight line passing through the origin is used as a threshold.

FIG. 11 shows a schematic procedure of a third embodiment of the method of the present invention.

FIG. 12 is a diagram showing an example in which a magnitude of a difference between a DC capacitance value and an AC capacitance value is set as a threshold value.

FIG. 13 is a diagram illustrating an example of setting a magnitude of a difference between a DC capacitance value and an AC capacitance value as a threshold value.

FIG. 14 is a diagram showing a determination procedure of a conventional capacitance measuring method.

FIG. 15 is a diagram showing a determination procedure of a determination method by a conventional terminal device with a separation function.

FIG. 16 is a diagram showing a determination procedure of a conventional pulse measurement method.

FIG. 17 is a diagram showing an example of a pulse waveform measured by a conventional pulse measurement method.

[Explanation of symbols]

L ₁ , L ₂ Measuring point Z ₀ is the characteristic impedance of the cable Z _t Terminal equipment l Distance from measuring point to terminal equipment Y _in Input admittance C _DC DC capacity C _AC AC capacity C _T DC capacity C _DC value and AC capacity difference ε threshold line θ with C _AC value, the steps of δ threshold sa~sx execution procedure

Claims (3)

[Claims] 1. A method for determining the quality of a balanced pair line, which comprises determining the state of the balanced pair line by measuring the capacity of a terminal device connected to the terminal part of the balanced pair line to be diagnosed, in the following steps: a) By changing the length of the balanced pair line in sequence, the DC capacity and the AC at the specified frequency are calculated or tested for the state (normal state) and the state (terminal disconnection) where the terminal equipment is connected to the end of this line. The step of obtaining the capacitance and obtaining the threshold line ε consisting of a straight line or a curve separating the normal region and the disconnection region on the graph showing the correlation between the two capacitances, (b) direct current and the frequency used in step a In the step of measuring the capacitance between the lines to be diagnosed by alternating current, (c) the value obtained in step b is compared with the threshold line ε obtained in step a, and this value is compared with the threshold line DC capacitance. Step proceeds to Step d, to step e when in the AC capacitor side when in,
(D) Step of determining that there is a terminal device at the end of the balanced pair line and proceeding to step f, (e) Step of determining that there is no terminal device at the end of the balanced pair line and proceeding to step g, (f)
A method for determining the quality of a balanced pair line, comprising: a step of determining that the balanced pair line is normal; and (g) a step of determining that the balanced pair line is disconnected. 2. The method of determining the quality of a balanced pair line, which comprises determining the state of the balanced pair line by measuring the capacity of a terminal device connected to the terminal part of the balanced pair line to be diagnosed, in the following steps: h) Altering the length of the balanced pair line in sequence and calculating or experimenting the DC capacity and AC at the specified frequency for the state (normal state) and the state (disconnected state) where the terminal equipment is connected to the end of this line. The capacity is obtained, and on the graph showing the correlation between the two capacities, a straight line that passes through the origin and separates the normal area and the broken area is obtained, and the ratio θ of the AC capacity to the DC capacity represented by the slope of this straight line is calculated. A step of setting this as a threshold value, (i) a step of measuring the capacitance between the lines to be diagnosed by a direct current and an alternating current of the frequency used in the step h, (j)
The step of obtaining the ratio of the AC capacity to the DC capacity from the value obtained in step i, (k) The value of the ratio of the capacity obtained in step j and the value of the ratio θ obtained in step h are compared, and the step is obtained in step j. If the value of the capacity ratio is smaller than θ, go to step 1; if equal or larger, go to step m; (l) Step to determine that there is a terminal device at the end of the balanced pair line, and go to step n; (M) Steps of determining that there is no terminal device at the end of the balanced pair line and proceeding to step o, (n) determining that the balanced pair line is normal, and (o) determining that the balanced pair line is disconnected A method for determining the quality of a balanced pair line, which is characterized by the following. 3. A method for determining the quality of a balanced pair line, which comprises determining the state of the balanced pair line by measuring the capacity of a terminal device connected to the terminal part of the balanced pair line to be diagnosed. p) By calculation or experiment,
The step of selecting the frequency at which the AC capacity increases linearly with the increase in the distance to the terminal equipment, (q) the length of the balanced pair line is sequentially changed, and the terminal equipment is connected to the end of this line The DC capacity and the AC capacity at the frequency selected in step p are obtained by calculation or experiment for the (normal state) and the non-connected state (disconnection state), and the threshold value δ having a value less than or equal to the difference value between these two capacities is set. Step (r) measuring the capacitance between the lines to be diagnosed by the direct current and the alternating current of the frequency used in step q,
(S) a step of obtaining the difference between the value of the DC capacity and the value of the AC capacity obtained in step r, (t) comparing the difference obtained in step s with the threshold value δ obtained in step q, and from δ If larger, go to step u, and if δ or less, step v
Step (u), it is determined that there is a terminal device at the end of the balanced pair line, and the process proceeds to step w, (v) It is determined that there is no terminal device at the end of the balanced pair line, and the process proceeds to step x, (w ) A method for determining the quality of a balanced pair line, which includes the steps of determining that the balanced pair line is normal, and (x) determining that the balanced pair line is disconnected.