JP2000307571A - Medium test auxiliary device for network termination device and medium test method - Google Patents

Abstract

(57) [Problem] To provide a medium test auxiliary device for a network termination device capable of suppressing power consumption during communication and measuring a conductor resistance. A media test auxiliary device for a network termination device, disposed between a network termination device and a media tester, connected to each of the network termination device and each of the media testers by a subscriber line. A first positive polarity detection circuit that detects a positive DC current flowing through the subscriber line and outputs a result, and a second positive polarity circuit that detects a positive DC current flowing through the subscriber line and outputs the result. A detection circuit, an inversion polarity detection circuit for detecting an inversion polarity DC current flowing through the subscriber line and outputting a result, the first positive polarity detection circuit, the second positive polarity detection circuit, and the inversion polarity A test control unit that outputs a switching signal in accordance with an output of the detection circuit, and a switching unit that connects or disconnects a DC termination resistor that allows a current having an inverted polarity to flow in accordance with the switching signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network termination device using a subscriber line signaling system in ISDN digital communication, and more particularly to a media test auxiliary device for a network termination device for detecting a conductor resistance of the network termination device and a media test. About the method.

[0002]

2. Description of the Related Art In an ISDN digital communication system,
Subscriber line signaling (TTC JT-G961 "Digita
l Transmission System on Metallic Local Lines for
ISDN Basic Route Access ") makes a transmission request and a disconnection request depending on the presence or absence and the polarity of the direct current of the subscriber line.

A conventional network terminating device will be described with reference to FIG. In FIG. 7, reference numeral 1 denotes a network terminating device, which includes a transmission circuit 2, an inversion polarity detection circuit 5, a layer 1 control unit 7, and a layer 2 control unit 8. The network terminating device 1 is connected to a line terminating device 10 via subscriber lines L1 and L2.

When the inversion polarity detection circuit 5 detects that the voltage polarities of the subscriber lines L1 and L2 have become the inversion polarity (L1 <L2), the inversion polarity detection circuit 5 sends a layer 1 activation signal to the layer 1 control unit 7 to transmit the layer 1 Requests activation of the control unit 7. Thereby, the layer 1 is activated. On the other hand, when the inversion polarity is not detected, the inversion polarity detection circuit 5 requests the layer 1 control unit 7 to stop the layer 1 control unit 7 by a layer 1 start signal. Thereby, the layer 1 stops.

Next, the operation at the time of transmission will be described. First, when there is a transmission request from the layer 2 control unit 8 to the layer 1 control unit 7, the transmission request is notified by outputting a transmission signal from the layer 1 control unit 7 to the transmission circuit 2. . When receiving the transmission signal, the transmission circuit 2 closes the DC termination and sends a DC current to the subscriber lines L1 and L2 to notify the line termination device 10 that there is a transmission request.

When the line termination device 10 detects that a DC current has flowed through the subscriber lines L1 and L2, the line termination devices 10 and L2 receive a direct current.
The voltage polarity of No. 2 is inverted (L1 <L2). At this time, the network termination device 1 continues to supply a direct current to the subscriber lines L1 and L2 through the inversion polarity detection circuit 5.

At the time of transmission, the line terminating device 10 maintains the inverted polarity and maintains the layer 1 while the direct current flows through the subscriber lines L1 and L2.

FIG. 8 is a time chart at the time of transmission of the network termination device 1 shown in FIG. As shown in FIG. 8, at the time of transmission (time t1 in FIG. 8), the network termination device 1 performs the DC termination of the subscriber lines L1 and L2 by the transmission signal from the layer 1 control unit 7 (see FIG. 8D). Then, the value of the current flowing through the subscriber lines L1 and L2 changes from I1 to I2 (see FIG. 8C). The line terminating device 10 determines that there is a transmission request by detecting the change in the current value, and
1. Invert the polarity of L2 (see FIG. 8A). At the time of calling, the line terminating device 10 transmits the subscriber lines L1 and L2.
While the current I2 flows through the inverter (see FIG. 8).
(C)), layer 1 is maintained.

When the layer 1 is stopped (time t2 in FIG. 8), the line terminating device 10 sets the polarities of the subscriber lines L1 and L2 to positive (L1> L2) (see FIG. 8 (c)), and the network terminating device. 1
To the layer 1 stop. At this time, since the inverted polarity is not detected in the network termination device 1, the inverted polarity detection circuit 5
Requests the layer 1 control unit 7 to stop the layer 1 control unit 7 with a layer 1 start signal, the transmission signal is turned "OFF" (see FIG. 8D). by this,
Layer 1 stops.

Next, the operation at the time of an incoming call will be described. At the time of an incoming call, the line terminating device 10 notifies the network terminating device 1 of the incoming call by inverting the polarities of the subscriber lines L1 and L2. When the inversion polarity detection circuit 5 of the network terminating device 1 detects the inversion polarity, the inversion polarity detection circuit 5 sends a layer 1 activation signal to the layer 1 control unit 7 to notify the incoming call. Thereby, the layer 1 is activated.

At the time of an incoming call, the line termination device 10 has a function of maintaining the reverse polarity and maintaining the layer 1 irrespective of the presence or absence of a direct current in the subscriber lines L1 and L2. The subscriber line L1,
The direct current continues to flow through L2.

FIG. 9 is a time chart when the network termination device 1 shown in FIG. 7 receives a call. As shown in FIG. 9, at the time of an incoming call (time t1 in FIG. 9), the network terminating equipment 1 is connected to the subscriber lines L1, L2.
Is detected (see FIG. 9C), and this is notified to the layer 1 control unit 7 (see FIG. 9D).

When Layer 1 is stopped (time t2 in FIG. 9), the line terminator 10 sets the polarities of the subscriber lines L1 and L2 to positive (L1> L2) (see FIG. 9C), and the network terminator. 1
To the layer 1 stop. At this time, in the network terminating device 1, since the inverted polarity is not detected, the inverted polarity detection circuit 5 sends the layer 1 control unit 7 the layer 1 control unit 7 by the layer 1 start signal (see FIG. 9D). Request a stop. Thereby, the layer 1 stops.

Next, the medium test will be described. At the time of the medium test, the medium tester 12 is connected to the subscriber lines L1 and L2 instead of the line termination device 10. FIG. 10 is a time chart at the time of the medium test. The medium here refers to the subscriber lines L1 and L2 in a state where the line termination device 10 is not connected.
And the devices connected to the subscriber lines L1 and L2. The line termination device 10 is disconnected from the subscriber lines L1 and L2 (time t1 in FIG. 10), and the medium tester 12 is connected to the subscriber lines L1 and L2 (see FIGS. 10A and 10B). When measuring the insulation resistance between the subscriber lines L1 and L2, the medium tester 12 connects a constant voltage source with a positive polarity (L1> L2). At this time, the current I is supplied to the subscriber lines L1 and L2.
3 flows (see FIG. 10C). The medium tester 12 calculates the insulation resistance between the subscriber lines L1 and L2 from the current value I3 and the voltage value of the constant voltage source.

When measuring the conductor resistance between the subscriber lines L1 and L2 (time t2 in FIG. 10), the medium tester 12 connects a constant current source with the reverse polarity (L1 <L2). When the inversion polarity detection circuit 5 detects the inversion polarity, it sends an incoming signal to the layer 1 control unit 7 to notify the incoming call, and since the layer 1 attempts to start, a current I2 flows through the subscriber line (FIG. 10).
(C)). The medium tester 12 calculates the conductor resistance from the current value I2 and the voltage value between the subscriber lines L1 and L2.

When the test is completed (time t3 in FIG. 10)
Then, the medium tester 12 is disconnected from the subscriber lines L1 and L2, and the line termination device 10 is connected to the subscriber lines L1 and L2 with a positive polarity. At this time, since the inversion polarity is not detected by the inversion detection circuit 5 (see FIG. 10D), the layer 1 control unit 7
, A stop of layer 1 is notified by a layer 1 activation signal (see FIG. 10E).

[0017]

By the way, in the network termination device 1 shown in FIG. 7, when the DC current of the subscriber lines L1 and L2 is not used as power for operating the network termination device 1. However, if Layer 1 is being activated by an outgoing request from Layer 2, the network terminating device 1
Since it is necessary to continuously supply a direct current to the subscriber lines L1 and L2 to the line termination device 10 through the inversion polarity detection circuit 5,
There is a problem that it requires a lot of power. In view of such circumstances, power consumption during communication can be suppressed,
A network terminating device that can also reduce the power of the line terminating device has been proposed. However, the network terminating device that can suppress power consumption during communication has a problem that a media test cannot be performed by a media tester according to the related art.

The present invention has been made in view of such circumstances, and when a network terminating device that can suppress power consumption during communication is used, there is no problem with using a conventional medium tester. It is an object of the present invention to provide a medium test auxiliary device for a network termination device and a medium test method capable of performing a medium test.

[0019]

The invention according to claim 1 is arranged between a network termination device and a media tester in an ISDN digital communication system, and each of the network termination device, the media tester, and a subscriber. A media test auxiliary device for a network termination device connected by a line, wherein the media test auxiliary device for a network termination device detects a positive DC voltage applied to the subscriber line and outputs a result. 1 positive polarity detection circuit, a second positive polarity detection circuit for detecting a positive DC voltage applied to the subscriber line and outputting the result, and a DC of an inverted polarity applied to the subscriber line. An inversion polarity detection circuit that detects a voltage and outputs a result, and a test control that outputs a switching signal according to the outputs of the first positive polarity detection circuit, the second positive polarity detection circuit, and the inversion polarity detection circuit Unit, according to the switching signal, Characterized by comprising a switching unit for connecting or cutting the rolling load that draws the polarity of the current.

According to a second aspect of the present invention, the test control unit is configured to control the output of the first positive polarity detection circuit, the second positive polarity detection circuit, and the output of the inverted polarity detection circuit to be all off. And outputting a switching signal to the switching unit.

According to a third aspect of the present invention, there is provided a medium test method using the medium test auxiliary device for a network termination device according to the first or second aspect, wherein the medium test method comprises the steps of: The subscriber line is connected to a constant voltage source having a positive polarity, and a medium test is performed in a state where a load for flowing a current having a reverse polarity is connected.

According to a fourth aspect of the present invention, in the medium test, at least one of an insulation resistance test of the subscriber line, a capacity test of the subscriber line, and an external voltage test of the subscriber line is performed. It is characterized by being performed.

According to a fifth aspect of the present invention, there is provided a medium test method for measuring a conductor resistance using the medium test auxiliary device for a net termination device according to the first or second aspect, wherein the medium test method comprises the steps of: When the tester is connected to the subscriber line, a constant current source is connected to the subscriber line with a reverse polarity, and a load flowing a current of the reverse polarity is connected to the subscriber line, the current flowing through the load and the voltage between the subscriber lines are connected. It is characterized in that the conductor resistance is measured from the value.

[0024]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; First, before describing the medium test auxiliary device for a network termination device, the configuration and operation of the network termination device capable of suppressing power consumption during communication will be described with reference to FIG. In the figure, reference numeral 11 denotes a network terminating device that can suppress power consumption during communication, and includes a transmission circuit 2, a positive current detection circuit 3, a polarity change determination unit 4, an inversion polarity detection circuit 5, and a switching unit 6. , A layer 1 control unit 7 and a layer 2 control unit 8. Reference numeral 10 denotes a line terminating device, which is connected to the network terminating device 11 by the subscriber lines L1 and L2.

The transmission circuit 2 shown in FIG.
1. The transmission switch SW1. The positive current detection circuit 3 includes a photocoupler PC1 and a diode D1. In addition, the inversion polarity detection circuit 5
Is infinite (open).
The switching unit 6 includes a DC termination resistor RD1, a diode D
2. It is constituted by a changeover switch SW2.

Here, as the initial state of the network termination device 11, the transmission switch SW1 of the transmission circuit 2 is in the "OFF" state, and the positive current detection signal of the photocoupler PC1 of the positive current detection circuit 3 is "OFF". The description will be made assuming that the changeover switch SW2 of the changeover unit 6 is in the “OFF” state.

Next, the operation at the time of starting the incoming call will be described with reference to FIG. FIG. 4 is a time chart showing the operation of the network terminating device 11 and the line terminating device 10 shown in FIG.

The line terminating device 10 changes the polarities of the subscriber lines L1 and L2 from the positive polarity (L1> L2) to the inverted polarity (L1 <L2) at the time of starting the incoming call (time t1 in FIG. 4) (FIG. 4). (C), the inversion polarity detection circuit 5 outputs a layer 1 activation signal (see FIG. 4 (h)). At this time, the photocoupler P of the positive current detection circuit 3 of the network termination device 11
Since the positive polarity current detection signal of C1 remains “OFF”, the polarity change determination unit 4 determines that transmission is not to be started, and holds the switch SW2 of the switching unit 6 at “OFF”. At this time, since the DC input resistance value of the inversion polarity detection circuit 5 is infinite, no current flows through the subscriber lines L1 and L2.

Next, the operation at the time of starting the transmission will be described. FIG.
4 is a time chart showing the operation of the network terminating device 11 and the line terminating device 10 shown in FIG.

First, when a transmission request signal is notified from the layer 2 control unit 8 to the layer 1 control unit 7 (at time t in FIG. 3).
1) The transmission signal from the layer 1 control unit 7 is turned “ON” (see FIG. 5E). In response, the transmission switch S
W1 is turned “ON”, and a current I2 flows through the subscriber lines L1 and L2 through the DC terminating resistor R1 (see FIG. 5B). Subsequently, the photocoupler P of the positive current detection circuit 3
The positive current detection signal of C1 is turned “ON” (FIG. 5).
(See (f)), the line terminating device 10 detects the current I2. After a certain time (time t2 in FIG. 5), the line termination device 10 changes the polarities of the subscriber lines L1 and L2 to the positive polarity (L1
> L2) to the inverted polarity (L1 <L2) (FIG. 5 (c)
), The positive-polarity current detection signal of the photocoupler PC1 of the positive-polarity current detection circuit 3 of the network termination device 11 becomes “OFF” (see FIG. 5F).

At this time, since the DC termination resistor RD1 is disconnected by the changeover switch SW1, the subscriber line L
1, no current flows between L2,
0 detects that the current stops flowing through the subscriber lines L1 and L2 (time t3 in FIG. 5), and changes the polarities of the subscriber lines L1 and L2 from the reverse polarity (L1 <L2) to the positive polarity (L1> L2). (See FIG. 5C). At this time, the subscriber lines L1, L
2, the current I2 flows through the DC terminating resistor R1 (see FIG. 5B), so that the positive current detection signal of the photocoupler PC1 of the positive current detection circuit 3 becomes "ON" (see FIG. 5F). The polarity change determination unit 4 determines that the positive polarity current detection signal of the photocoupler PC1 of the positive polarity current detection circuit 3 is first turned “ON”, then “OFF”, and further turned “ON” within a certain period of time. Is detected, the polarity change determination unit 4 sets the changeover switch SW2 of the changeover unit 6 to “ON” (see FIG. 5G), and connects the DC termination resistor RD1.

At this time, since the polarities of the subscriber lines L1 and L2 are positive (L1> L2), the subscriber lines L1 and L2 are
2, a current I2 flows through the DC terminating resistor R1, and the line termination device 10 detects the current I2.
At time t4), the line termination device 10 changes the subscriber line polarity from the positive polarity (L1> L2) to the inverted polarity (L1 <L2) (see FIG. 5 (c)), and applies a DC termination resistor to the subscriber lines L1 and L2. R
A current I2 flows through D1. At this time, the network termination device 1
1, the photocoupler PC1 of the positive current detection circuit 3
The positive polarity current detection signal changes from “ON” to “OFF” (see FIG. 5F), and if the “OFF” state continues for a certain period of time, the layer 1 control unit 7 is notified that the transmission has been accepted and enters the communication state.

Next, the cutting operation will be described. The disconnection (time t5 in FIG. 5) is performed when the line terminating device 10 sets the
Make the polarity of L2 positive (L1> L2) (FIG. 5 (c))
Reference). At this time, the subscriber line L
1, the current I2 flows through the DC termination resistor R1 through the DC terminating resistor R1 (see FIG. 5B), so that the positive current detection signal of the photocoupler PC1 of the positive current detection circuit 3 becomes "ON" (FIG. 5F). ), The polarity change determination unit 4 outputs a disconnection signal, and thereby outputs the line disconnection information to the layer 1 control unit 4.
And the changeover switch SW2 of the changeover unit 6 is set to “OFF” (see FIG. 5 (g)), and the DC termination resistor R
Disconnect D1. The layer 1 control unit 7 sets the transmission signal to “O
FF ”(see FIG. 5D), and the transmission switch SW1
To "OFF", the subscriber lines L1, L2
(See FIG. 5 (b)).
In this state, a standby state is entered.

As described above, when the DC current of the subscriber lines L1 and L2 is not used as the power for operating the network terminating device 1, transmission and reception are possible even if the DC input resistance of the inverting polarity circuit is increased. Since current can be prevented from flowing through the subscriber lines L1 and L2 at the time of an incoming call, power can be reduced. Further, at the time of transmission, the network terminating device 1 receives a constant current power supply from the line terminating device 10, but by reducing the resistance value of the DC terminating resistor RD1, the power consumption in the network terminating device 1 can be reduced.

Next, a description will be given of a medium test of the network termination device 11 shown in FIG. FIG. 6 shows the network termination device 1 shown in FIG.
6 is a time chart illustrating an operation at the time of a first medium test. Here, an insulation resistance test will be described as an example of the medium test. First, the line termination device 10 is disconnected from the subscriber lines L1 and L2 (time t1 in FIG. 6), and the medium tester 12 is connected to the subscriber lines L1 and L2 (see FIGS. 6A and 6B).
In order to measure the insulation resistance between the subscriber lines L1 and L2, the medium tester 12 connects a constant voltage source with a positive polarity (L1> L2). At this time, a current I3 flows through the subscriber lines L1 and L2 (see FIG. 6C). The medium tester 12 calculates the current value I
3 and the insulation resistance between the subscriber lines L1 and L2 is measured from the voltage value of the constant voltage source.

Here, in the medium test performed by connecting a constant voltage source between the subscriber lines L1 and L2 with a positive polarity, the subscriber line L
1 and L2 and a capacity test between the subscriber lines L1 and L2. A medium test performed by short-circuiting the subscriber lines L1 and L2 via resistors (by setting the voltage of the constant voltage source to 0 [V]) includes an external voltage test of the subscriber lines L1 and L2. In this external voltage test, the subscriber lines L1, L2
Is short-circuited, the voltage value between the subscriber lines L1 and L2 should ideally be 0 [V]. However, in fact, 0
Since it does not become [V], the voltage value measured here becomes the external voltage. The capacity test and the external voltage test are performed at the same timing as the insulation resistance test shown in FIG.

Note that all of the insulation resistance test, the capacitance test, and the external voltage test may be performed, but at least one of these tests may be performed.

Next, when measuring the conductor resistance between the subscriber lines L1 and L2 (time t2 in FIG. 6), the medium tester 12 connects a constant current source with an inverted polarity (L1 <L2). At this time, the positive polarity current detection signal of the photocoupler PC1 of the positive polarity current detection circuit 3 of the network termination device 11 remains “OFF” (see FIG. 6F), so that the polarity change determination unit 4 does not start transmission. And the changeover switch SW2 of the changeover unit 6 is kept “OFF”. At this time, the subscriber lines L1, L2
Does not flow (see FIG. 6C). Therefore,
Since the medium tester 12 calculates the conductor resistance from the current value and the voltage value between the subscriber lines, the medium resistance cannot be calculated.

When the test is completed (time t3 in FIG. 6), the medium tester is disconnected from the subscriber line, and the line termination device is connected to the subscriber line with a positive polarity. At this time, since the reverse polarity is not detected by the network terminating device 11, the layer 1 control unit
Notifies start signal stop.

As described above, since the conductor resistance cannot be calculated for the network terminating device 11, the network terminating device 11 is connected between the network terminating device 11 and the medium tester 12.
One that can measure the conductor resistance of the first embodiment is a medium test auxiliary device for a network termination device.

Next, a medium test auxiliary device for a network termination device will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a medium test auxiliary device A for a network termination device. In FIG. 1, reference numeral 11 denotes the network termination device shown in FIG. The medium test auxiliary device A used for the network termination device 11 includes a positive polarity detection circuit 13, a positive polarity detection circuit 14, an inverted polarity detection circuit 1,
5, a test control unit 16 and a switching unit 17. The positive polarity detection circuit 13 includes a Zener diode Dz1 (Zener voltage Vz0), a resistor Rn1, a diode Dn1, and a photocoupler PCn1. Further, the positive polarity detection circuit 14 includes a Zener diode Dz2 (Zener voltage VZ).
z0), a resistor Rn2, a diode Dn2, and a photocoupler PCn2. In addition, the inversion polarity detection circuit 1
5 is a resistor Rr1, a diode Dr1, and a photocoupler PC
r1. The switching unit 17 includes a DC termination resistor Rt, a diode Dt, and two changeover switches SWt. Note that the resistance value of the resistor Rr1 is substantially equal to the DC input resistance value of the inversion polarity detection circuit 5 shown in FIG.

When the positive polarity detection signal 1 of PCn1, the positive polarity detection signal 2 of PCn2, and the inverted polarity detection signal 1 of PCr1 are all "OFF", the switch SWt is switched to the contact point Ptst by the SWt switching signal from the test control unit 16. Connected. On the other hand, when all of the positive polarity detection signal 1 of PCn1, the positive polarity detection signal 2 of PCn2, and the inverted polarity detection signal 1 of PCr1 are not “OFF”, that is, when at least one of these signals is “ON”, The changeover switch SWt is connected to the contact point Pcom by a SWt changeover signal from the test control unit 16. When the SWt switching signal from the test control unit 16 is “ON”, the switching unit 17
Connect to the contact Ptst, and if the SWt switching signal is “OFF”, connect to the contact Pcom.

Next, the operation during the medium test will be described. FIG.
Is a time chart showing the operation at the time of the medium test. During the medium test, the line termination device 10 connected to the subscriber lines L1 and L2 is disconnected from the subscriber lines L1 and L2 (time t1 in FIG. 2), and the medium tester 12 is connected to the subscriber lines L1 and L2. (See FIGS. 2A and 2B). At this time, the medium tester 12 performs a medium test by connecting a constant voltage source (voltage Vt <Vz0) with a positive polarity (L1> L2) to the subscriber line. here,
The tests performed are, as described above, an insulation resistance test, a capacitance test, and an external voltage test.

Note that all of the insulation resistance test, the capacitance test, and the external voltage test may be performed, but at least one of these tests may be performed.

By performing these tests, the photocoupler PC1 of the positive current detection circuit 3 of the network termination device 11
The positive polarity current detection signal (see FIG. 3), which is the output of
F ”, the polarity change determination unit 4 determines that the transmission is not activated, and sets the changeover switch SW2 of the changeover unit 6 to“ O ”.
FF ”.

Further, by performing at least one of an insulation resistance test, a capacitance test, and an external voltage test, the photocoupler P of the positive polarity detection circuit 13 of the medium test auxiliary device A is tested.
Positive polarity detection signal 1 of Cn1, positive polarity detection signal 2 of photocoupler PCn2 of positive polarity detection circuit 14, and inverted polarity detection signal 1 of photocoupler PCr1 of inverted polarity detection circuit 15
Are all "OFF". At this time, the test control unit 16 responds to the SWt switching signal (see FIG.
7 is switched from the contact point Pcom to the contact point Ptst.

After the measurement of the insulation resistance, the medium tester 12 connects the constant current source with the subscriber line polarity reversed (L1 <L2) and measures the conductor resistance (time t2 in FIG. 2). At this time, the positive polarity detection signal 1 of the photocoupler PCn1 of the positive polarity detection circuit 13 (see FIG. 2E), the positive polarity detection signal 2 of the photocoupler PCn2 of the positive polarity detection circuit 14 (see FIG. 2H), and Photocoupler PCr1 of inversion polarity detection circuit 15
The inverted polarity detection signal 1 of FIG.
F ", the test control unit 16 holds the switch SWt of the switching unit 17 at the contact point Ptst in response to the SWt switching signal (see FIG. 2G). Also, the inverting polarities are applied to the subscriber lines L1 and L2 through the resistor Rt (FIG.
(See FIG. 2 (c)). The medium tester 12 calculates the conductor resistance from the current I2 and the voltage between the subscriber lines L1 and L2.

However, before the measurement of the conductor resistance, a SWt switching signal is output from the test control unit 16, the switch SWt of the switching unit 17 is switched to the contact point Ptst, and a DC termination resistor is connected between the subscriber lines L1 and L2. Must be connected. Therefore, before conducting the medium test for measuring the conductor resistance, the insulation resistance test, the capacity test,
The switching unit 1 performs at least one external voltage test.
It is necessary to switch the changeover switch SWt of No. 7 from the contact point Pcom to Ptst.

The cutting (time t3 in FIG. 2) is performed by the medium tester 1
2 is switched to the line terminating device 10 (FIGS. 2A and 2B).
reference). At this time, the voltage value between the joining lines L1 and L2 is Vc
(Vc> Vz0), and the positive polarity detection signal 2 of the photocoupler PCn2 of the positive polarity detection circuit 14 is turned “ON” (see FIG. 2 (h)), so that the test control unit 16 outputs the SWt switching signal (FIG. g)), the switch SWt of the switching unit 17 is switched from the contact point Ptst to Pcom. At this time, the photocoupler PCn of the positive polarity detection circuit 13
1, the positive polarity detection signal 1 is “ON”, and the positive polarity detection circuit 14
Since the positive polarity detection signal 2 of the photocoupler PCn2 and the inversion polarity detection signal 1 of the photocoupler PCr1 of the inversion polarity detection circuit 15 are “OFF”, the test controller 16 sets SWt
The changeover switch Swt of the changeover unit 17 is held at the contact point Pcom by the changeover signal.

As described above, the network terminating device 11 and the medium tester 12 capable of suppressing the power consumption during communication shown in FIG.
Since the medium test auxiliary device A for the network terminating device is provided in between, the medium test can be performed accurately.

The medium test auxiliary device A shown in FIG.
It may be configured to be incorporated in the network terminating device 11. Further, the medium test auxiliary device A may be configured to be incorporated in the medium tester 12. The medium test auxiliary device A is connected between the network terminating device 11 and the medium tester 12, but is preferably arranged so as to be connected as close to the network terminating device 11 as possible.

[0052]

As described above, according to the present invention, when the DC current of the subscriber line is not used as the power for operating the network termination device, the DC input resistance of the inversion polarity detection circuit is increased. Also allows outgoing and incoming calls,
Since current can be prevented from flowing through the subscriber line at the time of an incoming call, the effect of reducing power consumption can be obtained. Further, at the time of transmission, the network terminating device receives a constant current power supply from the line terminating device. However, by reducing the resistance value of the DC terminating resistor, it is possible to obtain an effect that power consumption in the network terminating device can be reduced. .

Further, according to the present invention, since the medium test auxiliary device is provided between the network termination device and the medium tester for the purpose of power reduction, accurate measurement of the conductor resistance is performed for the network termination device. There is also an effect that it becomes possible to perform

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a timing chart showing an operation of the medium test auxiliary device A for the network termination device shown in FIG.

FIG. 3 is a block diagram showing a configuration of a network termination device 11 shown in FIG.

FIG. 4 is a timing chart showing an operation of the network termination device 11 shown in FIG.

FIG. 5 is a timing chart showing an operation of the network termination device 11 shown in FIG.

6 is a timing chart showing an operation of the network terminating device 11 shown in FIG.

FIG. 7 is a block diagram showing a configuration of a network terminating device 1 according to a conventional technique.

8 is a timing chart showing an operation of the network terminating device 1 shown in FIG.

9 is a timing chart showing the operation of the network terminating device 1 shown in FIG.

FIG. 10 is a timing chart showing the operation of the network termination device 1 shown in FIG.

[Explanation of symbols]

 A: Medium test auxiliary device, 1: Network termination device, 2: Oscillator circuit, 3: Positive current detection circuit, 4: Polarity change determination unit, 5: Reversal polarity detection Circuit 6 Switching unit 7 Layer 1 control unit 8 Layer 2 control unit 10 Line termination device 11 Network termination device 12 Medium tester , 13 ... Positive polarity detection circuit, 14 ... Positive polarity detection circuit, 15 ... Inversion polarity detection circuit, 16 ... Test control unit, 17 ... Switching unit.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H04Q 1/20 H04L 13/00 309Z 5K050 3/42 104 315Z F-term (Reference) 5K019 AA02 AB05 AC03 BA05 BA40 BA52 BA61 BB35 BB36 BB37 BB39 CA05 CB05 CB08 CC10 CD02 DA03 EA21 5K027 AA10 BB04 CC02 EE17 FF02 GG06 KK03 LL06 MM04 5K030 GA14 HC04 JA08 JA10 JL08 KA14 LA12 MA08 MC01 5K034 AA15 CC06 CC07 EE13 FF04H03 KK04 GG04 KK BB03 BB06 DD30 EE23 EE30 FF04 FF05 FF17 GG04 GG13 GG15

Claims (5)

[Claims] 1. A medium test auxiliary device for a network termination device which is arranged between a network termination device and a media tester in an ISDN digital communication system and is connected to each of the network termination device and the media tester by a subscriber line. A first positive polarity detection circuit that detects a positive direct current voltage applied to the subscriber line and outputs a result; and A second positive polarity detection circuit for detecting the applied positive DC voltage and outputting the result; and an inverted polarity detection circuit for detecting the inverted DC voltage applied to the subscriber line and outputting the result. A test control unit that outputs a switching signal in accordance with the outputs of the first positive polarity detection circuit, the second positive polarity detection circuit, and the inversion polarity detection circuit; Connect or load current A switching unit for disconnecting, and a medium test auxiliary device for a network termination device. 2. The test control unit, when all of the outputs of the first positive polarity detection circuit, the second positive polarity detection circuit, and the inverted polarity detection circuit are turned off, switches the test control unit. The medium test auxiliary device for a network termination device according to claim 1, wherein a switching signal is output. 3. A medium test method using the medium test auxiliary device for a network termination device according to claim 1 or 2, wherein the medium test method comprises: connecting a medium tester to a subscriber line; A medium test method characterized in that a medium test is performed in a state in which a constant voltage source having a positive polarity is connected to a power line and a load for flowing a current having an inverted polarity is connected. 4. The medium test according to claim 1, wherein at least one of an insulation resistance test of the subscriber line, a capacity test of the subscriber line, and an external voltage test of the subscriber line is performed. Item 4. The medium test method according to Item 3. 5. A medium test method for measuring conductor resistance using the medium test auxiliary device for a network termination device according to claim 1 or 2, wherein the medium test method comprises: connecting a medium tester to a subscriber line. In a state where a constant current source is connected to the subscriber line with an inverted polarity and a load for flowing a current of the inverted polarity is connected to the subscriber line, a conductor resistance is measured from a current flowing through the load and a voltage value between the subscriber lines. A medium test method, characterized in that: