JPS6155318B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for easily testing the continuity of a called party's circuit using signals used to set up a call in a time division telephone exchange.

In the case of time-division telephone exchanges, the continuity test of the called party's circuit for each call is performed when the communication path between the calling party and the called party is established by the central controller and the transmission of a ring tone signal to the called party begins. Usually done before. Figure 1 shows a block diagram of such a telephone exchange. When the central controller CC determines that calling party A is calling called party B, a test pattern is generated on called party B's side. A test pattern (for example, a repeating signal of "01") is sent from the device TPG in the time slot assigned to the called party. The path is TPG→inserter I→time switch TSW→demultiplexer DMPX→subscriber circuit LC. In particular, as shown in FIG. 2B, when the central controller CC gives the loop circuit control signal LOCC to the selector SEL in the called subscriber circuit LC (the ringing tone to the called subscriber is In the subscriber circuit LC the test pattern path is looped back towards the multiplexer MPX so that a digital loop is created (unsent). Then, it is connected to the calling party via the time switch TSW, and the above-mentioned test pattern signal is taken out by the pick-up device (dropper) D in front of the calling party's time switch TSW, and the check circuit CHK sends that signal to the TPG transmission test. Check by comparing with the pattern. When it is determined that the communication path for called party B is normal based on the matching of the patterns, the ringing tone related to FIG. 2C is sent out to call called party B. When the patterns do not match, it is assumed that the called subscriber's circuit is faulty and measures such as prohibition of incoming calls are taken.
When the called party B answers, the callee enters an off-hook state as shown in FIG. 2A. A detailed diagram of the digital loop creation section in the subscriber circuit LC is shown in FIG. The selector SEL is configured by, for example, an AND circuit and an OR circuit connected as shown in the figure, and when a loop circuit control signal LOCC is applied, a reception path RP and a transmission path TP are connected. Regarding the ring tone, when the ring tone control signal RGC (C in Figure 2) is sent out, the relay R in Figure 3 operates and its contact r switches.
The ringing tone sending device RGT and subscriber B are connected and a ringing tone is sent out. In Figure 3, LP is a loop circuit detector, H is a hybrid circuit, and DEC
is a pulse signal to analog signal decoder,
COD indicates an encoder that converts analog signals into pulse signals. Therefore, in this device, it is necessary for the central controller CC to control the loop circuit control signal shown in FIG. 2B as a signal other than the normal ringing tone signal to be sent out before sending out the ringing tone. This increases the processing amount of the central controller CC, complicates the interface between the line and the central controller, and increases costs. In addition, it is necessary to set the continuity test time before the start of ringing tone transmission, and as shown in Fig. 1, an inserter I and a dropper D, and a test pattern generation circuit TPG are required to control the transmission of the test pattern signal. This makes the device complicated.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned drawbacks and to provide a method that enables continuity testing with a simple configuration without requiring digital loop circuit control signals.

Embodiments of the present invention shown in the drawings will be described below. The block configuration diagram shown in FIG. 4 shows an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate the same parts. PSW is a pad switch, PSM is a pad switch control memory, and test pattern signals are obtained from both PSW and PSM as described later. FIG. 5 is a diagram corresponding to FIG. 3, showing a circuit of a digital loop creation section in the subscriber circuit LC. In this case, a folding digital loop circuit can be formed simply by applying the ring tone control signal RGC. That is, the ringing tone control signal serves both of forming a digital loop circuit and controlling the relay R for sending out the ringing tone.
(Refer to the time chart in Figure 6) Central control unit CC
can perform a continuity test by operating the test pattern generation circuit in synchronization with sending out the ring tone control signal. P, Q, and R in FIG. 6 represent waveform diagrams at the same reference numerals in FIG. By storing signals in the form of test patterns in a part of the switch memory PSM, the central control
Read by CC command and switch PSW
A test pattern can be sent out via .
This test pattern signal is sent to the called subscriber circuit LC via the time switch TSW. Next, it is folded back in the digital loop circuit as described above,
It reaches the calling party via multiplex MPX and time switch TSW, extracts the time slot at dropper D, and sends it to the check circuit. Therefore, in this case, there is no need to provide a special test pattern signal generation circuit.

In this way, according to the present invention, the ring tone control signal is used in the subscriber circuit to form a digital loop, so there is no need for the central control unit to specifically generate a control signal for forming the digital loop, unlike in the prior art. In addition, the conventional control signal for loop formation usually had to be generated before the ringing tone, making the timing process complicated, but with the present invention, the continuity test starts at the same time as the ringing tone, so the timing process is simple. This has the advantage of not affecting the time it takes to connect the called party.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional time division exchanger, Fig. 2 is an operation time chart for conducting a continuity test for Fig. 1, and Fig. 3 is a block diagram of a conventional time division exchanger.
4 is a block configuration diagram showing an embodiment of the present invention. FIG. 5 is a detailed diagram of the digital loop creation section in the subscriber circuit shown in FIG. Figure 6 is the fourth
This is an operation time chart shown in the figure. CC...Central control unit, TPG...Test pattern generator, I...Inserter, TSW
...Time switch, D...Take-out device (dropper), LC...Subscriber circuit, CHK...Check circuit, RGC...Ring tone control signal, RGT...Ring tone sending device.

Claims (1)

[Scope of Claims] 1. At the beginning of the called party paging period of the time division telephone exchange, the receiving path and the sending path in the called party's circuit are connected by a digital loop circuit using a control signal to form a loop. A called party circuit continuity test method for a time-division telephone exchange in which a test pattern signal sent through a time-division communication path is looped back by the loop and sent through the communication path again to a check circuit to test the continuity state of the communication path. A method for testing continuity of a called party circuit, characterized in that a ringing relay control signal is used to configure a loop path in the called party circuit. 2 A test pattern signal for continuity testing is obtained by a variable transmission loss insertion device installed in the time-division communication path and digitally inserts transmission loss in a variable manner, and is sent to the called party. )
2. A continuity test method for a circuit of a called party according to claim 1, wherein the time slot signal of the called party is extracted and sent to a check circuit, and checked by the check circuit.