JP3522579B2 - Medium test auxiliary device for network termination device and medium test method - Google Patents

Description

Detailed Description of the Invention

[0001]

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

[0002]

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

A conventional network terminating device will be described with reference to FIG. In FIG. 7, reference numeral 1 is a network terminating device, which is composed of a transmission circuit 2, an inverted 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 by subscriber lines L1 and L2.

When the reverse polarity detection circuit 5 detects that the voltage polarities of the subscriber lines L1 and L2 have become the reverse polarities (L1 <L2), the layer 1 control section 7 receives a layer 1 start signal and outputs the layer 1 Request activation of the control unit 7. This activates layer 1. On the other hand, when the reverse polarity is not detected, the reverse polarity detection circuit 5 requests the layer 1 control unit 7 to stop the layer 1 control unit 7 with a layer 1 activation signal. This causes Layer 1 to stop.

Next, the operation at the time of calling will be described. First, when the layer 2 control unit 8 issues a call request to the layer 1 control unit 7, the layer 1 control unit 7 notifies the call request by outputting a call signal to the transmitting circuit 2. . When the transmission circuit 2 receives this transmission signal, it 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 terminating device 10 detects that a direct current has flowed through the subscriber lines L1 and L2, the subscriber lines L1 and L2.
The voltage polarity of 2 is set to the reverse polarity (L1 <L2). At this time, the network terminating device 1 continues to flow a direct current through the inversion polarity detection circuit 5 to the subscriber lines L1 and L2.

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

FIG. 8 is a time chart when the network terminating device 1 shown in FIG. 7 makes a call. As shown in FIG. 8, at the time of origination (time t1 in FIG. 8), the network termination device 1 uses the origination signal (see FIG. 8D) from the layer 1 control unit 7 to terminate the DC termination of the subscriber lines L1 and L2. When this is done, 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 call origination request by detecting the change in the current value, and the subscriber line L
The polarities of 1 and L2 are reversed (see FIG. 8A). The line terminating device 10 uses the subscriber lines L1 and L2 when making a call.
While the current I2 is flowing in the
(See (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 the positive polarity (L1> L2) (see FIG. 8 (c)), and the network terminating device is used. 1
To notify the layer 1 stop. At this time, since the reverse polarity is not detected in the network terminating device 1, the reverse polarity detection circuit 5
Requests the layer 1 control unit 7 to stop the layer 1 control unit 7 with a layer 1 activation signal, the transmission signal becomes “OFF” (see FIG. 8D). by this,
Layer 1 stops.

Next, the operation upon receipt of an incoming call will be described. At the time of incoming call, the line terminating device 10 notifies the network terminating device 1 of the incoming call by reversing the polarities of the subscriber lines L1 and L2. When the reverse polarity detection circuit 5 of the network terminating device 1 detects the reverse polarity, it sends a layer 1 activation signal to the layer 1 control unit 7 to notify the incoming call. This activates layer 1.

At the time of an incoming call, the line terminating device 10 has a function of retaining the reverse polarity and maintaining the layer 1 regardless of the presence or absence of the direct current of the subscriber lines L1 and L2. The subscriber line L1 through the polarity detection circuit 5,
Continue to apply DC current to L2.

FIG. 9 is a time chart when the network terminating device 1 shown in FIG. 7 receives an incoming call. As shown in FIG. 9, at the time of an incoming call (at time t1 in FIG. 9), the network terminating device 1 uses
It is detected that the polarity of (1) has been inverted (see FIG. 9C), and the layer 1 control unit 7 is notified of this (see FIG. 9D).

When the layer 1 is stopped (time t2 in FIG. 9), the line terminating device 10 sets the polarities of the subscriber lines L1 and L2 to positive polarity (L1> L2) (see FIG. 9 (c)), and the network terminating device is used. 1
To notify the layer 1 stop. At this time, since the reverse polarity is not detected in the network terminating device 1, the reverse polarity detection circuit 5 notifies the layer 1 control unit 7 of the layer 1 control unit 7 by the layer 1 activation signal (see FIG. 9D). Request a stop. This causes Layer 1 to stop.

Next, the medium test will be described. During the medium test, the medium tester 12 is connected to the subscriber lines L1 and L2 instead of the line terminating device 10. FIG. 10 is a time chart during the medium test. The medium here means the subscriber lines L1 and L2 in a state where the line terminating device 10 is not connected.
And the devices connected to the subscriber lines L1 and L2. The line terminating 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 positive polarity (L1> L2). At this time, the current I is applied to the subscriber lines L1 and L2.
3 flows (see FIG. 10 (c)). 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 the constant current source with the reverse polarity (L1 <L2). When the reverse polarity detection circuit 5 detects the reverse polarity, it sends an incoming signal to the layer 1 control unit 7 to notify the incoming call, and the layer 1 tries to start up, so that the current I2 flows through the subscriber line (FIG. 10).
(See (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 ends (time t3 in FIG. 10)
Then, the medium tester 12 is disconnected from the subscriber lines L1 and L2, and the line terminator 10 is connected to the subscriber lines L1 and L2 with a positive polarity. At this time, the inversion detection circuit 5 does not detect the inversion polarity (see FIG. 10D), so the layer 1 control unit 7
Is notified of the stop of layer 1 by a layer 1 activation signal (see FIG. 10E).

[0017]

By the way, in the network terminating device 1 shown in FIG. 7, when the direct currents of the subscriber lines L1 and L2 are not used as electric power for operating the network terminating device 1. However, if the layer 1 is being activated by the transmission request from the layer 2, the network terminating device 1
Since it is necessary to keep the direct current flowing through the subscriber lines L1 and L2 to the line terminating device 10 through the reverse polarity detection circuit 5,
There is a problem that it requires a lot of power. In view of such circumstances, it is possible to reduce power consumption during communication,
A network terminating device that can reduce the power of the line terminating device has been proposed. However, the network terminating device capable of suppressing the power consumption during communication has a problem that the medium tester according to the related art cannot perform the medium test.

The present invention has been made in view of the above circumstances, and when a network terminating device capable of suppressing power consumption during communication is used, the medium tester according to the prior art can be used without any problem. An object of the present invention is to provide a medium test auxiliary device for a network terminating device capable of performing a medium test and a medium test method.

[0019]

The invention according to claim 1 is arranged between a network terminating device and a medium tester in an ISDN digital communication system, and each of the network terminating device and the medium tester and a subscriber. A medium test auxiliary device for network terminator connected by a line, wherein the medium test auxiliary device for network terminator detects a positive DC voltage applied to the subscriber line and outputs a result. No. 1 positive polarity detection circuit, a second positive polarity detection circuit for detecting a positive polarity DC voltage applied to the subscriber line and outputting the result, and a reverse polarity DC applied to the subscriber line. An inversion polarity detection circuit that detects a voltage and outputs the 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. Section, 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, in the case where the test control section outputs all of the outputs of the first positive polarity detection circuit, the second positive polarity detection circuit and the inversion polarity detection circuit. And outputting a switching signal to the switching unit.

A third aspect of the present invention is a medium test method using the medium test auxiliary device for network terminator according to the first or second aspect, wherein the medium test method uses a medium tester as a subscriber. It is characterized in that the medium test is carried out in a state in which it is connected to a line, a positive voltage source is connected to this subscriber line, and a load for flowing a current of reverse polarity is connected.

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

A fifth aspect of the present invention is a medium test method for measuring a conductor resistance using the medium terminating device medium test auxiliary device according to the first or second aspect, wherein the medium test method is a medium test method. When a tester is connected to a subscriber line, a constant current source with reverse polarity is connected to this subscriber line, and a load that flows current with reverse polarity is connected, the voltage between the current flowing through the load and the subscriber line It is characterized in that the conductor resistance is measured from the value.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION A medium test auxiliary device for a network terminating device according to an embodiment of the present invention will be described below with reference to the drawings. First, before describing the medium test auxiliary device for a network terminating device, the configuration and operation of the network terminating device capable of suppressing power consumption during communication will be described with reference to FIG. In the figure, reference numeral 11 is a network terminating device capable of suppressing power consumption during communication, and includes a transmission circuit 2, a positive polarity current detection circuit 3, a polarity variation determination unit 4, an inversion polarity detection circuit 5, and a switching unit 6. , Layer 1 control unit 7 and layer 2 control unit 8. Reference numeral 10 is a line terminating device, which is connected to the network terminating device 11 by subscriber lines L1 and L2.

The oscillator circuit 2 shown in FIG.
1. The transmitter switch SW1. The positive current detection circuit 3 is composed of a photocoupler PC1 and a diode D1. In addition, the reverse polarity detection circuit 5
The DC input resistance value of is infinite (open).
Further, the switching unit 6 includes a DC terminating resistor RD1 and a diode D.
2. The switch SW2.

Here, as the initial state of the network terminating 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 in the "OFF" state. 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 operations 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 reverse polarity (L1 <L2) when the incoming call is activated (time t1 in FIG. 4) (FIG. 4). (See (c)), and the inverted 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 terminating device 11
Since the positive polarity current detection signal of C1 remains “OFF”, the polarity variation determination unit 4 determines that the transmission is not started, and holds the changeover switch SW2 of the switching unit 6 in “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 transmission will be described. Figure 5
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 the layer 2 control section 8 notifies the layer 1 control section 7 of a call origination request signal (time t in FIG. 3).
1), the transmission signal from the layer 1 control unit 7 becomes "ON" (see FIG. 5 (e)). In response to this, 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). Then, the photocoupler P of the positive current detection circuit 3
The positive current detection signal of C1 becomes "ON" (Fig. 5).
(See (f)), the line terminating device 10 detects this current I2. After a certain time (time t2 in FIG. 5), the line terminating device 10 changes the polarities of the subscriber lines L1 and L2 to positive (L1).
> L2) to reverse polarity (L1 <L2) (FIG. 5 (c))
5), the positive current detection signal of the photocoupler PC1 of the positive current detection circuit 3 of the network terminating device 11 is "OFF" (see FIG. 5 (f)).

At this time, since the DC terminating resistor RD1 is disconnected by the changeover switch SW1, the subscriber line L
Since no current flows between 1 and L2, the line termination device 1
0 detects that the current has stopped flowing to the subscriber lines L1 and L2 (time t3 in FIG. 5), and the polarities of the subscriber lines L1 and L2 are reversed (L1 <L2) to positive (L1> L2). (See FIG. 5C). At this time, the subscriber lines L1 and L
Since the current I2 flows through the DC terminating resistor R1 in 2 (see FIG. 5 (b)), the positive current detection signal of the photocoupler PC1 of the positive current detection circuit 3 becomes “ON” (see FIG. 5 (f)). 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 first becomes “ON”, then “OFF”, and then “ON” within a certain period of time. Then, the polarity variation determination unit 4 turns on the changeover switch SW2 of the changeover unit 6 (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, the line terminating device 10 detects the current I2, and after a predetermined time (see FIG. 5).
At time t4), the line terminating device 10 changes the polarity of the subscriber line from the positive polarity (L1> L2) to the reverse polarity (L1 <L2) (see FIG. 5C), and the DC termination resistance is applied to the subscriber lines L1 and L2. R
A current I2 flows through D1. At this time, the network terminating device 1
Photocoupler PC1 of the positive current detection circuit 3 in FIG.
The positive polarity current detection signal of is changed from "ON" to "OFF" (see FIG. 5 (f)), and if the "OFF" state continues for a certain period of time, the layer 1 control unit 7 is notified as transmission acceptance and enters the communication state.

Next, the cutting operation will be described. At the disconnection (time t5 in FIG. 5), the line terminating device 10 causes the subscriber line L1,
The polarity of L2 is positive (L1> L2) (FIG. 5 (c))
See)). At this time, the subscriber line L
Since the current I2 flows through the DC terminating resistor R1 to the terminals 1 and L2 (see FIG. 5B), the positive current detection signal of the photocoupler PC1 of the positive current detection circuit 3 becomes “ON” (FIG. 5 (f)). The polarity change determination unit 4 outputs the disconnection signal, so that the line disconnection information is transmitted to the layer 1 control unit 4
To the switch termination switch SW2 of the switching unit 6 (see FIG. 5 (g)), and the DC terminating resistor R
Disconnect D1. The layer 1 control unit 7 sends the transmission signal “O
FF ”(see FIG. 5D), and the transmission switch SW1
By turning off the subscriber lines L1 and L2
So that no resistance current will flow through it (see FIG. 5B).
In this state, the standby state is entered.

As described above, when the DC currents of the subscriber lines L1 and L2 are not used as power for operating the network terminating device 1, even if the DC input resistance of the inverting polarity circuit is increased, it is possible to make and receive calls. Therefore, it is possible to prevent the current from flowing through the subscriber lines L1 and L2 at the time of incoming call, so that the power consumption can be reduced. Further, at the time of transmission, the network terminating device 1 is supplied with a constant current 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 medium test of the network terminating device 11 shown in FIG. 3 will be described. FIG. 6 shows the network terminating device 1 shown in FIG.
3 is a time chart showing the operation during the medium test of No. 1; Here, an insulation resistance test will be described as an example of the medium test. First, the line terminating 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 positive polarity (L1> L2). At this time, a current I3 flows through the subscriber lines L1 and L2 (see FIG. 6 (c)). The medium tester 12 uses this current value I
3 and the voltage value of the constant voltage source, the insulation resistance between the subscriber lines L1 and L2 is measured.

Here, in the medium test performed by connecting a constant voltage source with positive polarity between the subscriber lines L1 and L2, the subscriber line L
There are an insulation resistance test between 1 and L2 and a capacity test between subscriber lines L1 and L2. Further, the medium test performed by short-circuiting the subscriber lines L1 and L2 via a resistor (with the voltage of the constant voltage source set to 0 [V]) includes an external voltage test of the subscriber lines L1 and L2. In this external voltage test, subscriber lines L1 and L2
, The voltage value between the subscriber lines L1 and L2 should ideally be 0 [V]. But actually 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.

All of the insulation resistance test, the capacity 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 the constant current source with the reverse 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 terminator 11 remains "OFF" (see FIG. 6 (f)), so the polarity variation determination unit 4 does not start transmission. Therefore, the changeover switch SW2 of the changeover unit 6 is kept in the “OFF” state. At this time, subscriber lines L1 and L2
A current does not flow in (see FIG. 6 (c)). Therefore,
Since the medium tester 12 calculates the conductor resistance from this current value and the voltage value between the subscriber lines, the conductor 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 terminating device is connected to the subscriber line with positive polarity. At this time, the network terminating device 11 does not detect the reverse polarity.
Notify that the start signal has stopped.

As described above, since the conductor resistance cannot be calculated for the network terminating device 11, the network terminating device 1 is connected between the network terminating device 11 and the medium tester 12.
A medium test auxiliary device for a network terminating device is one in which the conductor resistance of No. 1 can be measured.

Next, a medium test auxiliary device for a network terminating device will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a medium test auxiliary device A for a network terminating device. In FIG. 1, reference numeral 11 is the network terminating device shown in FIG. The medium test auxiliary device A used for the network terminating device 11 includes a positive polarity detection circuit 13, a positive polarity detection circuit 14, and an inversion polarity detection circuit 1.
5, the test control unit 16 and the 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 uses the Zener diode Dz2 (Zener voltage V
z0), a resistor Rn2, a diode Dn2, and a photocoupler PCn2. In addition, the reverse polarity detection circuit 1
5 is a resistor Rr1, a diode Dr1, a photocoupler PC
r1. The switching unit 17 is composed of a DC termination resistor Rt, a diode Dt, and two changeover switches SWt. The resistance value of the resistor Rr1 is approximately the same as the DC input resistance value of the inversion polarity detection circuit 5 shown in FIG.

The changeover switch SWt is connected to the contact Ptst by the SWt changeover signal from the test control section 16 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". Connected. On the other hand, when the positive polarity detection signal 1 of PCn1, the positive polarity detection signal 2 of PCn2, and the reverse polarity detection signal 1 of PCr1 are not all “OFF”, that is, when at least one of these signals is “ON”, The changeover switch SWt is connected to the contact point Pcom by the SWt changeover signal from the test control unit 16. If 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. Figure 2
[Fig. 6] is a time chart showing an operation during a 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 connects a constant voltage source (voltage Vt <Vz0) with a positive polarity (L1> L2) to the subscriber line and performs a medium test. here,
The tests performed are the insulation resistance test, the capacity test, and the external voltage test, as described above.

All of the insulation resistance test, the capacity 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 terminating device 11 will be described.
The positive current detection signal (see FIG. 3) that is the output of
Since it remains as “F”, the polarity variation determination unit 4 determines that the call is not activated, and sets the changeover switch SW2 of the changeover unit 6 to “O”.
Leave it as "FF".

Further, by performing at least one of the insulation resistance test, the capacity test and the external voltage test, the photocoupler P of the positive polarity detection circuit 13 of the medium test auxiliary device A is tested.
Cn1 positive polarity detection signal 1, positive polarity detection circuit 14 photocoupler PCn2 positive polarity detection signal 2 and reverse polarity detection circuit 15 photocoupler PCr1 reverse polarity detection signal 1
Are all "OFF". At this time, the test control unit 16 uses the SWt switching signal (see FIG. 2 (g)) to switch the switching unit 1.
The changeover switch SWt of No. 7 is changed from the contact point Pcom to Ptst.

After the insulation resistance measurement is completed, the medium tester 12 connects the constant current source with the subscriber line polarity being the reverse polarity (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 the reverse polarity detection circuit 15
Inversion polarity detection signal 1 (see FIG. 2 (f)) is all "OF".
Since it remains as “F”, the test control unit 16 holds the changeover switch SWt of the changeover unit 17 as the contact Ptst in response to the SWt changeover signal (see FIG. 2G). In addition, the subscriber lines L1 and L2 have reverse polarities through a resistor Rt (Fig. (D)).
Current I2 flows (see FIG. 2C). The medium tester 12 calculates the conductor resistance from the current I2 and the voltage value between the subscriber lines L1 and L2.

However, before this conductor resistance measurement, the SWt switching signal is output from the test control unit 16, the changeover switch SWt of the changeover unit 17 is switched to the contact Ptst, and the DC termination resistance is applied between the subscriber lines L1 and L2. Must be connected. Therefore, before conducting the medium test for measuring the conductor resistance, the above-mentioned insulation resistance test, capacity test,
At least one test of the external voltage test is performed, and the switching unit 1
It is necessary to change 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 becomes “ON” (see FIG. 2 (h)). Therefore, the test control unit 16 causes the SWt switching signal (see FIG. 2 ( g)), the changeover switch SWt of the changeover unit 17 is changed over from the contact point Ptst to Pcom. At this time, the photocoupler PCn of the positive polarity detection circuit 13
Positive polarity detection signal 1 of 1 is “ON”, positive polarity detection circuit 14
Since the positive polarity detection signal 2 of the photocoupler PCn2 and the reverse polarity detection signal 1 of the photocoupler PCr1 of the reverse polarity detection circuit 15 are “OFF”, the test control unit 16 sets SWt.
By the switching signal, the changeover switch Swt of the changeover unit 17 is held as the contact Pcom.

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 between and, the medium test can be accurately performed.

The medium test auxiliary device A shown in FIG.
The configuration may be incorporated in the network terminating device 11. The medium test auxiliary device A may be incorporated in the medium tester 12. Further, the medium test auxiliary device A is connected between the network terminating device 11 and the medium tester 12, but it is desirable that the medium test auxiliary device A is arranged so as to be connected to a position as close to the network terminating device 11 as possible.

[0052]

As described above, according to the present invention, when the direct current of the subscriber line is not used as the power for operating the network terminator, the direct current input resistance of the reverse polarity detection circuit is increased. Can also make and receive calls,
Since it is possible to prevent current from flowing through the subscriber line when an incoming call arrives, the effect of reducing power consumption is obtained. Further, at the time of transmission, the network terminating device receives constant current power from the line terminating device, but by reducing the resistance value of the DC terminating resistor, it is possible to reduce the power consumption in the network terminating device. .

Further, according to the present invention, since the medium test auxiliary device is provided between the network terminating device and the medium tester for the purpose of reducing power consumption, accurate conductor resistance measurement is performed for this network terminating device. The effect that it becomes possible to obtain is also obtained.

[Brief description of 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 a medium test auxiliary device A for network terminator shown in FIG.

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

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

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

6 is a timing chart showing the 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 the 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.

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

[Explanation of symbols]

A ... Medium test auxiliary device, 1 ... network terminating device, 2 ... oscillation circuit, 3 ... Positive current detection circuit, 4 ... Polarity change determination unit, 5 ... Inversion polarity detection circuit, 6 ... switching unit, 7 ... Layer 1 control unit, 8 ... Layer 2 control unit, 10 ... Line termination device, 11: Network terminating 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.

Continuation of front page (56) Reference JP-A-61-77460 (JP, A) JP-A-10-136087 (JP, A) JP-A-9-69879 (JP, A) JP-A-6-169335 (JP , A) JP 63-280555 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04L 12/02 H04M 1/24 H04M 3/30

Claims (5)

(57) [Claims] 1. A medium test auxiliary device for a network terminating device, which is arranged between a network terminating device and a medium tester in the ISDN digital communication system and is connected to each of the network terminating device and the medium tester by a subscriber line. Wherein the medium test auxiliary device for network terminator includes a first positive polarity detection circuit for detecting a positive DC voltage applied to the subscriber line and outputting the result; A second positive polarity detection circuit for detecting a positive polarity DC voltage applied and outputting a result, and an inversion polarity detection circuit for detecting a reverse polarity DC voltage applied to the subscriber line and outputting the result A test control unit 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; Connect a load that carries current or A medium test auxiliary device for a network terminating device, comprising: a switching unit for disconnecting. 2. The test control unit instructs the switching unit when outputs of the first positive polarity detection circuit, the second positive polarity detection circuit, and the inversion polarity detection circuit are all turned off. The medium test auxiliary device for a network terminating device according to claim 1, wherein a switching signal is output. 3. A medium test method using the medium test auxiliary device for network terminator according to claim 1 or 2, wherein the medium test method connects a medium tester to a subscriber line, and A medium testing method, characterized in that a positive voltage constant voltage source is connected to the main line and a medium test is performed in a state in which a load for flowing a current of reverse polarity is connected. 4. The medium test is performed by at least one of an insulation resistance test of the subscriber line, a capacitance test of the subscriber line, and an external voltage test of the subscriber line. Item 3. The medium test method according to Item 3. 5. A medium test method for measuring a conductor resistance using the medium test auxiliary device for a network terminating device according to claim 1, wherein the medium test method uses a medium tester for a subscriber line. Connected, a constant current source with reverse polarity is connected to this subscriber line, and in the state where a load that flows current with reverse polarity is connected, the conductor resistance is measured from the voltage flowing between the current flowing through the load and the subscriber line. A medium testing method characterized by the above.