JPS6134309B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a test line lead-in method in a trunk line circuit.

In exchanges (for example, time-division exchanges) that pass only low-level voice signal components through the communication network, a lead-in circuit is required for testing the trunk line or the communication network.

FIG. 1 is a trunk circuit diagram showing a conventional line lead-in system. In the figure, t ₀ to _{t 3} are line lead-in contacts, rv ₀ and rv ₁ are polarity reversal contacts, b is a trunk line loop closing contact, TST1 is a trunk line test circuit,
TST2 is communication network test circuit, T is transformer, RL
is a resistor lamp, D is a photodiode of a photocoupler that detects the loop current, V is a battery, and C is a capacitor. Contacts t ₀ to t ₃ , rv ₀ , rv ₁ , and b are contacts of relays T, RV, and B (not shown), and are controlled by a control device. First, the general operation of the trunk circuit will be explained.

When activation occurs from the relay wire, current flows through the path of relay wire A - contact t ₂ break - contact rv ₀ break - transformer T winding - photodiode D - low resistance lamp RL - battery V and is optically connected to photodiode D. The activation is notified to the control device through a phototransistor (not shown). The control device is relay B
, and sends a start confirmation signal to the opposite exchange through the route of ground air - contact B make - transformer T winding - contact rv ₁ break - contact t ₃ break - relay wire B. Thereafter, the selection code is received by a photodiode D in the case of a dial pulse, and via a transformer T in the case of a multifrequency signal system by a multifrequency receiver (not shown). When the called party answers, the control device relays RV.
is activated, the polarity is reversed using contacts rv ₀ and rv ₁ , and a response signal is sent to the opposite exchange.

Next, the line lead-in method during testing will be explained. When testing, relay T is operated. contact
When t ₀ to _{t 3} are activated, the trunk line is connected to the trunk line test circuit TST1 through make contacts t ₀ and t ₁ , and the exchange (talk network) side is connected to the trunk line test circuit TST1 through transfer contacts t ₂ and t ₃ . Connected to road network test circuit TST2. In this state, necessary tests are performed on both test circuits TST1 and TST2. In other words, in the conventional line lead-in method, 2
A relay having make contacts t ₀ , t ₁ and two transfer contacts t ₂ , t ₃ is required for each trunk circuit, which is not economical and increases the size of the circuit.

An object of the present invention is to provide an economical test line lead-in method by reducing the number of line lead-in contacts described above and making it possible to use an economical and small relay.

The present invention is a relay B (off normal relay) that operates in a trunk circuit after activation until the end of a call.
By inserting the make contact in series into the polarity reversal circuit, and inactivating relay B and reversing the polarity when testing the trunk line, the communication network side of the trunk circuit is disconnected, and when testing the communication network side, the test lead-in is performed. The test lead-in circuit is shared by connecting the circuits in parallel to the communication line, and the test equipment side can switch and use the test lead-in circuit.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows an embodiment of the present invention, where st ₀ , st ₁
The switching transfer contacts b ₀ and b ₁ for leading the communication line into the trunk line test circuit TST1 and the communication line test circuit TST2 are contacts of a relay B (not shown). Other symbols that are the same as those in FIG. 1 indicate the same things as in FIG. 1.

According to the present invention, a make contact is placed on the make side of contact rv ₀ .
b ₁ is included, but the general operating function of the trunk circuit is the same as in Figure 1. This is because the B relay is a relay that continues to operate after activation of the main trunk until the end of the call. Contacts st ₀ and st ₁ are also connected to test circuit TST1,
It is sufficient to add 2 transfer contacts to support TST2. The operation during the test will be explained.

When testing trunk lines, connect the relay T of the trunk circuit.
Activate RV and disable relay B. In this state, the factors on the communication network, battery V, and ground exchange side are disconnected due to the operation of contact rv ₀ and the non-operation of contacts b ₀ and b ₁ , so the trunk line test circuit TST1 is connected to make contact t ₀ , t ₁ , only the trunk line can be tested via the break side of the transfer contacts st ₀ , st ₁ .

Next, when testing the communication path network, the communication path network can be tested by the communication path test circuit TST2 by deactivating the relay RV and activating the contacts st ₀ and st ₁ from the previous state. At this time, since the trunk line side is not disconnected, the situation will not be exactly the same as in the case shown in Figure 1, but when the trunk circuit of the opposite exchange, which is generally connected via the trunk line, is not in use, it will simply be the downstream monitoring relay. is connected to the relay line, and this relay only monitors the operation of the B line of the relay line, that is, the operation of contact _b0 . Therefore, there is no problem since it does not affect the test from the test circuit TST2. Relay RV or Relay B
Various tests can be carried out depending on the operating or non-operating state of each.

It goes without saying that tests on trunk lines and call network must be conducted with the trunk circuits unused, but in this example, if there is activation from the trunk line side during the test, the DC loop will be interrupted. may be formed, which may affect the test.

However, this is not a practical problem since communication path network and trunk line tests are usually conducted at night when the usage rate of trunk circuits is low.

As mentioned above, by using relay B with two make contacts, the line lead-in contacts of the trunk circuit only need two make contacts, t ₀ and t ₁ , making it possible to construct an economical and compact trunk circuit. .

Note that even if two make contacts are used for relay B, the economical efficiency and size will not be affected as compared to a relay with one make contact.

[Brief explanation of the drawing]

FIG. 1 is a trunk circuit diagram showing a conventional line lead-in system, and FIG. 2 is an embodiment of the present invention. The symbols for the main parts of the figure are as follows. b ₀ , b ₁ ... Make contact of relay B that operates during a call, t ₀ , t ₁ ... Make contact of test pull-in relay T, rv ₀ , ₁ ... Transfer contact of relay RV for polarity reversal, TST1 ...Relay line test circuit, TST2
...Call path test circuit.

Claims (1)

[Claims] 1. In a trunk having a telephone line polarity rotation circuit for the front, a lead-in means is provided for connecting the telephone line to the test circuit, and the earth side of the current supply circuit is connected to the earth through the make contact of the off-normal relay,
The make side of the anti-relay in the polarity reversal circuit is connected to the earth through the make contact of the off-normal relay, and the make side of the reversal relay in the polarity reversal circuit is connected to the other make contact of the off-normal relay to form a polarity reversal circuit. When testing the trunk line side, the polarity reversal relay is operated and the off-normal relay is disabled, and only the trunk line side is drawn into the test circuit, and when the communication line side is tested, the drawing means is configured to A line lead-in method characterized by controlling the test circuit to be connected in parallel to the trunk communication line.