DE3003282A1 - Test word generator for digital exchanges - is connected onto highway in main switch block for test words to be sent out to loop back at subscriber's line circuit - Google Patents

Abstract

The test generator (PG) generates a digital test word and is connected to a central highway (Mux) in the switch block of the exchange (V). The central processor (CPU) control of the exchange (V) initiates the test word from the generator and selects the switching path back to the subscribers' line apparatus (LTA, LTD, ALA) where the test word is looped back to the generator (PG) for evaluation. On analogue exchange lines (LTA) and junctions (ALA) the two wire is open circuited (I/E) so that the test signal is looped back through the two wire/four wire hybrid (GA) into the CODEC in the subscriber's line unit (DTS) or junction term (AS). On digital exchange lines (LTD) the test word is a part of the synchronisation and alignment word sent around the subscriber's loop to the telephone (StD), a digital instrument.

Description

Procedure for checking record connections in an intermediary

management center of a digital time division multiplex telecommunications network, as well as possibly the lines connected to the exchange.

It is a procedure for monitoring the central functional parts one with the switching unit of a PCM exchange via a PCM time division multiplex line connected demultiplexer / multiplexer unit known (DT-OS 26 44 24), accordingly that during a certain time channel to synchronize the channel counter the demultiplexer / multiplexer unit sent from the switching unit Frame code word over the central parts of the unit for the mentioned time channel assigned decentralized functional part and from there after a mirroring in the opposite direction of transmission to the frame recognition circuit of the switching unit is returned.

As I said, it is a matter of monitoring a facility which is not part of the exchange and there again, insofar as it is are decentralized functional parts, only those that are part of the time channel are assigned in which the frame code word is sent. Other units, which are connected to the exchange via time division multiplex lines, namely the line terminals of these lines, are checked by the explained not recorded.

It is also a method of checking the voice mailbox of a PCM time division switching center has been proposed (DT patent application P 29 05 427), to a plurality of time division multiplexed lines are connected are, and both when writing on the incoming time division multiplex line branches occurring PCM words as well as when they are read out on the outgoing time division multiplex line branches is controlled optionally. According to this method, test connections are made via a certain of the time division multiplex lines connected to the voice mailbox are set up, in the course of this a PCM test word in each case one of the memory cells via the incoming Line branch of the specific time division multiplex line during the time slot of a specific Time channel and delayed by a pulse frame on the outgoing line branch the specific time division multiplex line is read out again and on the receiving end for a match is monitored with the previously sent PCM check word. That way one memory cell after the other is checked.

1-In the present invention, however, as indicated, to test the set circuits of an exchange of a digital time division multiplex telecommunications network and, if necessary, also to check those connected to the exchange Input / output lines, the test being up to the point of the set circuits connected connection lines and in the case of the lines themselves being recorded, what comes into question when connecting digital subscriber stations to in this subscriber station should extend into it.

The object of the invention is to provide a method that this Type of test with little effort from a central point in the switching system made possible.

This problem is solved in that at a central point of the Switching point a test generator is connected, which a digital test pattern creates a connection between the 2 connection point for both pdas and telecommunication information of the test generator and one of the connected lines is established, that by a switching measure initiated by the control of the exchange a return of the test pattern or the signal in the opposite direction of transmission is effected at the connection point, and that there an evaluation of the received test pattern respectively.

Signal takes place.

According to a further embodiment of the invention, during the test of set circuits of analog operated two-wire connection lines as a switching measure to return the test signal, the relevant connection line on the two-wire side the hybrid circuit arranged in the set circuit for the two-wire / four-wire transition separated, including any existing there belonging to an interface Switching contacts are used, and / or the line wires are used at this point the connection line short-circuited.

According to a further embodiment of the invention, during the test the set circuits of digitally operated two-wire connection lines as a switching measure the time control arranged in the set circuit to send the test sample back for four-wire transmission on two-wire lines different from normal operation controlled in such a way that the transmission periods are timed with the reception periods coincide.

If the set circuits for subscriber lines operated digitally Subscriber stations and these subscriber stations themselves are to be checked, are according to yet another embodiment of the invention measure Process the check bit combinations as part of a PCM word and / or as Part of the signaling word of synchronization word, signaling word and message signal blocks comprising at least one PCM word up to the subscriber station sent and sent back from there to the evaluation point in the exchange.

The invention is explained below with the aid of exemplary embodiments Referring to the drawing explained in more detail.

The drawing shows: FIG. 1 the block diagram of a PCM exchange with different types of record connections connected to it.

Fig. 2 illustrates message signal blocks such as in the case of the connection of digital subscriber stations to the exchange are transmitted on the subscriber line.

In the figure 1 is the actual core of a PCM exchange V, the contains, among other things, the coupling network, shown only schematically. To this Exchange V are various types of connection lines via various set circuits connected. So are analog operated subscriber lines LTA to the an analog subscriber station StA is connected via a digital one Subscriber set DTS connected to switch V. The digital subscriber substitute contains among other things a hybrid GA for the transition from the two-wire Subscriber connection line LTA on the continuing four-wire connection paths, a reception filter FE, a transmission filter FS and a device CODEC for analog-digital conversion and Digital-Analo.gxflungs. There is also an indication and setting interface 1 / E indicated at the for example, the call connection takes place and under certain circumstances a test coupling network can be connected via which certain special tests be made, however, in no connection with the invention Procedure stand. In the present context, contacts ka and kb for the line separation, which are normally used when such special tests be made. The devices explained are in the illustrated embodiment individually provided for each line and within the DTS subscriber set mentioned provided several times. In other embodiments, for example, the device CODEC assigned to several lines together.

The figure also shows the connection of digital subscriber lines LTD, which lead to digital subscriber stations StD, a subscriber set DTA, which, among other things, has a digital transmission device for each subscriber line LTD DÜ, to which a control circuit for four-wire transmission on two-wire lines belongs, and contains a signaling module SM.

As FIG. 1 also shows, analog trunk lines are ALA connected to the exchange V via an exchange set AS. Such an official sentence contains, like the explained digital subscriber set DTS, line-specific one setting and indication interface I / E with isolating contacts ka and kb, one Hybrid GA for two-wire to four-wire conversion, a reception filter FE and a Transmission filter FS and a CODEC circuit for analog-to-digital conversion and digital-to-analog conversion.

The control of the switching facilities as well as individual facilities of the sentences explained from a central control unit CPU in particular, in the context of interest here, it is possible to use a Control command from this control unit to actuate the aforementioned contacts ka and kb.

At a central point in the PCM exchange V, for example, such as shown in Figure 1, on a central multiplex rail Mux is according to the invention a test generator PG connected, which can generate digital test patterns and the a receiver, not shown separately here, is assigned for such test samples is.

Another central point of connection of the test generator comes a voice mailbox of the operator V is also possible.

The method according to the invention is described below with reference to FIG explained in more detail. First of all, the test of record connections is analogous operated two-wire connection lines, i.e. the subscriber connection lines LTA and the trunk lines ALA examined more closely. To consider a specific of these The test pattern generated by the test generator PG becomes lines like telecommunication information through switched to this line, the central control unit CPU the appropriate Provides setting commands. In the case shown, i.e. with the presence of isolating contacts ka and kb, the central control also separates the connection lines made at the I / E interface. The consequence of these measures is that the test sample, which is either generated directly as a digital signal or generated as an analog signal and then subjected to analog-to-digital conversion after passing through the device CODEC of the record circuits DTS or AS, where it undergoes a digital-to-analog conversion, des Transmission filter FS, and the hybrid circuit GA on the two-wire side of the hybrid circuit reflected at the point of line separation and in the opposite direction Transmission direction back to the test generator or

the one assigned to him. Recipient is returned, where there is a Analog-to-digital conversion undergoes. The determination of a correctly received test signal at this point is an indication of the proper functioning of the traversed Components of the system and in particular the set layouts. If any of the The facilities passed through on this test path are assigned to several lines, can be seen from the results of examinations made regarding these bodies Groups of connection lines formed relate to a certain extent to a fault localization make.

Instead of separating the connection line, that essentially then comes into question if the contacts ka and kb anyway for the reasons mentioned above are already present, the method according to the invention can also be carried out by that on the two-wire chain of the hybrid GA, the wires of the connecting line is short-circuited. This process variant will generally be provided for if with an already existing system the possibility of carrying out the according to the invention Procedure should be created retrospectively. Because the line simulation of the hybrid circuit generally a compromise for a variety of different line lengths represents, the mentioned short-circuit method leads to clearer results than the idle method. Furthermore, certain errors are detected by them, namely for example, an interruption in the transformer output winding of the hybrid circuit GA. However, the short-circuit method leads to an increased during testing Power demand.

The decision about which of the two variants to use should come, so depends on the practical conditions.

The testing of the DTA set circuits for digitally operated subscriber lines LTD, to which a digital subscriber station StD is connected, can be divided into two Variants are made.

One variant corresponds to the procedure explained above, with the difference that in the four-wire transmission method for two-wire Lines a transmission fork can not be assumed, so that by short-circuiting or disconnection of the connecting line does not necessarily mean a reflection of the test sample can be brought about. In this case it is rather the timing of the Transmit / receive switch operated so that the transmit time span with the receive time span coincides and, accordingly, the test sample coming to the line from there is looped back in the opposite direction of transmission.

The other variant is that the test pattern up to the digital Subscriber station StD sent and from there again assigned to the test generator PG Receiver is looped back. It is part of a message signal block, how it is sent to the digital subscriber station in normal operation and the, as FIG. 2 shows, e.g. from a synchronization word that is contained in a first pulse frame two bits of the bit combination 10 and in the seven subsequent pulse frames the Has bit combination 11, furthermore from a bit used for signaling, the Part of an eight-bit pulse frame that is part of the eight-bit frame sent signaling word, as well as two PCM words or two data words consists.

In this case, the check bit combination is part of one or both of the PCM words. In addition, the mentioned signaling word contains in this case a criterion that the aforementioned looping back in the digital subscriber station the PCM words of the news causes gnalblocks. This means the correct reception of the test bit combination at the location of the test generator PG, that except the devices of the set circuit, both the snrechway and the signaling path the subscriber line to the digital subscriber station is intact.

If, as indicated, certain devices of the sentence switching several connecting lines are assigned jointly, can be determined by the evaluation those associated with the groups of connection lines concerned Achieve error localization to a certain extent.

4 claims 2 figures L e r s e i t e

Claims (4)

Claims. 1J Procedure for checking record placements in an exchange a digital time division multiplex telecommunications network, as well as that to the exchange, if applicable connected lines, d a d u r c h e -k e n n n n z e i c h n e t that to a A test generator (PG) is connected to the central point (Mux) of the exchange (V) that generates a digital test pattern that as for telecommunications information a Connection between the connection point of the test generator and one of the connected lines (LTA, LTD, ALA) is made that through one of the Control (CPU) of the exchange (V) initiated switching measure a return of the test signal in the opposite direction of transmission to the connection point is effected, and that there is an evaluation of the test signal received. 2. The method according to claim 1 for testing set circuits analog operated two-wire connection cables, d u r c h e k e n n n z e i c h n e t that as a switching measure for returning the test signal, the connection line (LTA) on the two-wire side of the hybrid circuit arranged in the set circuit (DTS) (GA) is separated for the two-wire-four-wire transition, for which purpose if necessary Switching contacts available there belonging to an interface (I / E) (ka, kb) be exploited. 3. The method according to claim 1 for testing the set circuits digitally operated two-wire connecting cables, d u r c h e k e n n n z e i c h n e t that as a switching measure for returning the test signal, the one in the set circuit (LTD) arranged time control for the two-wire-four-wire transition different from the Normal operation is controlled so that the switch operation the transmission / reception circuit relevant transmission time spans temporally with the reception time spans coincide. 4. The method according to claim 1 for testing set circuits for subscriber lines digitally operated subscriber stations and these subscriber lines themselves, d a d u r c h e k e n n n z e i c h -n e t that the check bit combinations as a component of a PCM word of synchronization word, at least one signaling bit and at least message signal blocks comprising a PCM word to the subscriber station StD sent and from there, caused by a represented by signaling bits Criterion to be sent back to the evaluation point in the exchange (V).