JPH0133998B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication path test method for confirming the normality of a communication path using multi-frequency signals in a digital telephone exchange.

In conventional telephone exchanges, the communication path is an analog communication path using electromagnetic contacts, and the normality of this communication path is determined by a continuity test using a DC loop using a continuity test trunk and a return loop.

However, in a digital telephone exchange, the communication paths are multiplexed and are composed of a directional logical network, and the telephone exchange is usually performed by setting up multiple parallel communication paths for one logical path. There is. Therefore, a new test method for confirming the normality of the communication path has been required since the communication path is completely different from the conventional analog communication path.

The present invention was made in view of these points,
This system uses multi-frequency signal transmitters and receivers that are normally installed in exchanges, and is configured to test the normality of the communication path of a digital telephone exchange by using the multi-frequency signals sent and received by these. . This will be explained below using figures.

Figure 1 shows a multi-frequency signal transmitter MFS and a multi-frequency signal receiver MFR installed in a normal telephone exchange.
This shows an example of how to use this. When connecting to a previous station, connect the multi-frequency signal transmitter MFS, digital channel network TDNW, and outgoing trunk OGT as shown in the diagram, and send multi-frequency signals to the other station. Send a selection signal. In addition, the signal from the downstream station is connected to the multi-frequency signal receiver MFR, incoming trunk ICT, and digital channel network TDNW as shown in the diagram.
A multi-frequency signal receiver MFR receives a selection signal based on a multi-frequency signal arriving from the partner station. The digital channel network TDNW is a logical network that is multiplexed and has directionality, and normally exchanges PCM codes, for example, 8 bits.

In this way, the multi-frequency signal transmitter MFS and the multi-frequency signal receiver MFR are used in normal telephone exchange connections, and the multi-frequency signal sent from the multi-frequency signal transmitter MFS is PCM.
encoded signal and also multi-frequency signal receiver
MFR receives multifrequency signals in the form of PCM codes.

Since the above PCM encoding is a known technique, a detailed explanation will be omitted, but the above 8-bit PCM code has, for example, 1 bit for polarity, 3 bits for segment indication, and 3 bits for step number indication, as shown in Fig. 2. It consists of 4 bits. or,
Usually, one parity bit is added.

Figure 3 shows the PCM when transmitting a frequency signal that follows a SIN curve (for example, 400Hz with an input level of -9dBm).
This shows an example of encoding, and in the same curve, t ₀ ,
If the values sampled at each location of t ₁ and t ₂ are PCM encoded as shown in the configuration example in Figure 2, for example, t ₀ will be “11111111”, t ₁ will be “00010101”, and t ₂ will be “10101010”.
This results in a bit string of . As an example of one-frequency transmission, the above t ₀ , t ₁ ,
Each bit at each location of _t2 changes depending on the polarity and level (segment display, step number display).
Moreover, if a multi-frequency signal is used as the transmission signal, PCM
Each encoded bit will also vary randomly. Therefore, continuously transmitting a PCM encoded multi-frequency signal for a certain period of time is the same as transmitting an 8-bit random pattern.

The present invention has been made focusing on the above points,
The communication path test is performed as follows.

FIG. 4 is a block diagram showing an embodiment of the present invention, and is a block diagram of the multi-frequency signal transmitter shown in FIG.
This is done using MFS and multi-frequency signal receiver MFR.

Here, the call path test in the digital telephone exchange is performed by a maintenance person. For example, various information necessary for testing a desired communication path is added to a central processing unit (not shown) that controls the entire exchange through the operation of a maintenance person. When the central processing unit receives a communication path test request from the maintenance personnel as described above, it sends a multifrequency signal from the multifrequency signal transmitter MFS through the test point P of the digital communication path network TDNW that accommodates the requested communication path. Performs control to close the communication path to the signal receiver MFR. This control allows multi-frequency signal transmitter
A multi-frequency signal that continues for a certain period of time from MFS, to be more specific, it is an 8-bit PCM that has multiple random patterns and each bit changes randomly.
A predetermined coded multi-frequency signal is sent out. Next, the transmitted prescribed multi-frequency signal is exchanged every 8 bits at the point P under test of the communication path whose closure has been controlled, and is sent to and received by the multi-frequency signal receiver MFR.

In the above test operation, the multi-frequency signal receiver MFR receives the PCM-encoded multi-frequency signal sent out as it is as a bit string if the tested communication path is normal, and if a failure occurs. If there is an abnormality, either different bit sequences are received, or no signal is received at all. Then, after receiving the above, the normality of the communication path is confirmed by a central processing unit (not shown), and the result of the judgment is notified to the maintenance personnel by an output device such as a typewriter. be.

In addition, in the embodiment described above, a multi-frequency signal transmitter and a multi-frequency signal receiver, which are always used in a digital telephone exchange, are used, but the transmitter/receiver main body, which is normally arranged as ancillary equipment in this type of exchange, is used. It is possible to achieve the desired purpose and effect even if a communication path test is performed using a test multi-frequency signal transmitter and a multi-frequency signal receiver to check the normality of the communication channel. Furthermore, it is clear from the explanation in the text that the signal sent out from the multi-frequency signal transmitter used for the communication path test does not necessarily have to be multi-frequency, and may be one-frequency.

As detailed above, according to the present invention, the multi-frequency signal transmitter and multi-frequency signal receiver normally installed in a digital telephone exchange utilize the multi-frequency signals used during the telephone exchange. Therefore, it is possible to provide an economical test method that can confirm the normality of the communication path without using special test jigs.

[Brief explanation of drawings]

Figure 1 is a block diagram showing an example of the use of a multi-frequency signal transmitter/receiver, Figure 2 is a diagram showing an example of the configuration of a PCM code, and Figure 3 is a PCM when transmitting a SIN curve frequency signal.
FIG. 4, which is a diagram for explaining an example of encoding, is a block diagram showing an embodiment of the present invention. MFS is a multi-frequency signal transmitter, MFR is a multi-frequency signal receiver, ICT is an incoming trunk, OGT is an outgoing trunk,
TDNW is the digital communication path network and P is the point under test.

Claims (1)

[Scope of Claims] 1. In a digital telephone exchange comprising a multi-frequency signal transmitter and a multi-frequency signal receiver arranged via a digital channel network, A digital communication path network is set up through the point under test to the multi-frequency signal receiver, which is the same path as for general communication, and then the specified frequency signal digitized from the multi-frequency signal transmitter is transmitted as described above. It is characterized by continuously transmitting a multi-frequency signal to a multi-frequency signal receiver for a certain period of time via a set communication path, and then comparing the transmitted frequency signal and the received frequency signal to confirm the normality of the communication path. Call path test method.