JPS628060B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a test information transmission system in a time division switch, and particularly to a system in which test information control bits and voice bits are multiplexed and transmitted within the same channel.

C of conventional PCM (Pulse Code Modulation) line.
EPT (Committee of European Post and
In the telecommunications system, the voice channel (8 bits) and the common control line channel (8 bits) are separate channels. Also,
Even in the PCM-24 system, which is the standard system in Japan, there are separate channels for audio and common control lines (common signal lines). However, in the PCM-24 system, one of the specified number of channels (usually 6 channels)
The channel allocates 7 bits for audio and 1 bit for the signal line, and this signal line bit is used for monitoring the 4-wire SS (signal sending) and SR (signal receiving) lines.
Used for startup.

The common signal line channels mentioned above are usually allocated at a ratio of one channel to several dozen audio channels. This is natural when line efficiency is considered, but the number of common signal line channels is reduced to use them with high efficiency.

PCM transmission, such as the CEPT method, generally uses
With 128 channel multiplexing, 120 channels are assigned to audio and 8 channels are assigned to signals, but among the 8 channels for signals, both CEPT and PCM-24 formats are assigned.
In many cases, only 4 channels are used for common signal lines (the other 4 channels are vacant or reserved,
or used for frame synchronization, etc.).

As a result, out of 128 multiplexes (128 channels), 4
The channel will be used for a common signal line, but if duplication is also taken into consideration, a multi-frame system must be implemented with essentially two channels (16 bits). The idea is to extract two channels for common signal lines from 128 channels and collect them to create one signal format.

As an example, the signal format of 32 multi-frames will be explained as follows.

In other words, assuming a transmission path of 128 channels (nominally 8 Mb/s), the time per frame is 125 μ.
s) Extract the channel for the common signal line during the middle, and then extract the channel for the common signal line during the next 128 multiplexes. The above operation is repeated 32 times to create one common signal format.

The amount of information in this signal format is 8 bits x
2 channels x 32 frames = 512 bits, but it takes 125 μs x 32 = 4 ms to obtain this signal format (512 bits).

In other words, in the conventional method of transmitting test information through a common signal line, in order to obtain a large amount of information, the number of multi-frames must be increased, the time required for one signal format increases, and the time required to transmit test information increases. This increases the common signal line occupancy rate of the control signal line, putting pressure on other control signal transmission capacity. Also,
When real-time information is required, there is a limit to the number of multiframes.

SUMMARY OF THE INVENTION An object of the present invention is to provide a test information transmission system that eliminates the above-mentioned drawbacks of the prior art and makes effective use of digital multiplex channels.

In the test information transmission system of the present invention, in a time division switch, any channel in a digital multiplex line is assigned as a test channel. The test mix trunk replaces one or more specific bits in the test channel with test information bits from the test machine, and uses the remaining bits as test audio bits. The time-division exchange in which the terminal under test and the terminal test equipment are installed receives the digital multiplex line with test information inserted into the test channel, and switches it via the test demix trunk by a time-division switch; At this time, the test device trunk retains the test information bits from the test channel and sends them to the terminal tester, thereby making it possible to test the terminal under test. It is something.

In short, the test audio bits and test information bits can be used in any channel by installing the test demix trunk and the test demix trunk.

In other words, to explain in more detail, even if the quality of the voice of a test call is slightly lower than that of a general call, there is no problem in practical use. For this purpose, the remaining 1 bit is allocated for test information, a predetermined number of multi-frames are taken from the test channel, and a predetermined test information format is obtained. As a result, the common signal line channel is not used for transmitting test information.

An embodiment of the test information transmission method according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a frame configuration diagram of an embodiment of a PCM channel according to the present invention. In the figure, the total number of channels is 128, and channels 1 to
10, 12-63, 66-128 (CH1-1
0, CH12-63, CH66-128) are general audio channels, channels 64, 65 (CH
64, 65) are common signal line channels, and channel 11 (CH11) is a test channel. Each channel has an 8-bit configuration, and for the test channel CH11, 7 bits are allocated for test audio and 1 bit is allocated for test information.

FIG. 2 is a relay system diagram of an embodiment of the test information transmission system according to the present invention, and FIG. 3 is a circuit diagram of the test mix trunk in FIG. 2.

Here, 1 is a test device, 2 is a trunk for test calls, 3 is a test mix trunk, and 4 is a converter/digital converter that performs analog/digital mutual conversion and multiplexing, that is, multiplexing and demultiplexing, that is, demultiplexing. The multiplex device 5 is a time division switch, and is part of a time division switching center in which the test equipment is installed. Also, 6
is a time division switch, 7 is a conversion/multiplexing device similar to 4 above, 8 is a test device trunk, 9 is a terminal tester, 10 is a terminal under test, for example, a telephone under test, The above is part of what constitutes another terminal time division switching center.

Next, the operation will be explained in detail with reference to FIG.

The voice of the tester is sent from the test device 1 to the test call trunk 2, digitized (encoded) by the multiplexing/converting device 4, and multiplexed and time-coded as in the well-known PCM line. It is sent to the division switch 5.

The time division switch 5 switches the multiplexed PCM group (digital multiplex line) to the test mix trunk 3. On the other hand, test information is sent from the test device 1 to the test mix trunk 3 in the form of a digitized signal. In test mix trunk 3, tester audio channel 8
Among the bits, 1 bit is replaced with test information, and 8 bits of the test channel are mixed with 7 bits of audio and 1 bit of test information. The test channel that enters the time division switch 5 again from the test mix trunk 3 is treated completely in the same way as a general audio channel, and is switched to the station where the terminal tester 9 is located. The time division switch 6 of the terminal station has a converter and
The PCM group to the multiplexer 7 is switched via the test mix trunk 8. The test digital trunk 8 extracts only the last bit of test information from the test channel and sends it to the terminal tester 9. Based on the test information sent in this way, the terminal tester 9 selects the test line a.
or b, various tests are performed on the telephone under test 10. At the same time, the tester using the test device 1 can talk to the telephone under test 10 through the test audio channel (7 bits).

Next, the circuit operation of the test mix trunk shown in FIG. 3 will be explained.

The test mix trunk receives an 8MHz clock and a frame signal in addition to the multiplexed PCM group from the time division switch, counts bits and channels at counter 11, and counts the last bit of the test channel. At this time, an output pulse is sent from terminal A of the counter 11 for one clock. At this time, the AND gate 13 opens and one of the test information stored in the buffer 12 is
Bits are inserted into the PCM group via OR gate 15. By repeating this, all test information is inserted into each frame test channel.

The test mix trunk 8 has a function opposite to that of the above-described test mix trunk, and retains the last 1 bit of the 8 bits of the test channel and sends it to the terminal tester 9.

As described above, in the present invention, test audio bits and test information bits can be used in any channel by installing a test mix trunk and a test mix trunk.

According to the present invention, test information can be transmitted from the tester to the terminal tester without using the common signal channel, so the test channel can be transmitted without compressing the capacity of the common signal channel. A large amount of test information can be freely transmitted along with the tester's voice through the tester, and a remarkable effect can be obtained in improving the test function in the time division switching network.

[Brief explanation of the drawing]

FIG. 1 is a frame configuration diagram of an embodiment of a PCM channel according to the present invention, FIG. 2 is a relay system diagram of an embodiment of a test information transmission system according to the present invention, and FIG. FIG. 2 is a circuit diagram of a test mix trunk in FIG. 1... Test machine, 2... Trunk for test calls, 3
...Test Mix Trunk, 4,7...Conversion/
Multiplexer, 5, 6... Time division switch, 8... Test storage trunk, 9... Terminal testing device, 1
0...Telephone under test.

Claims (1)

[Claims] 1. In the time-division exchange, any channel in the digital multiplex circuit is assigned as a test channel, and in the time-division exchange in which the test equipment is installed, the digital multiplex circuit is switched by the time-division switch via the test mix trunk. At that time, the test mix trunk replaces one or more specific bits in the test channel with test information bits from the test device, uses the remaining bits as test audio bits, and makes sure that the terminal under test and the terminal test device The installed time-division switch receives the digital multiplex line with test information inserted into the test channel and switches it via the test demix trunk by a time-division switch. The test information transmission system is characterized in that the test information bits are retained from the test channel and sent to the terminal tester, thereby making it possible to test the terminal under test.