DE1177213B - Method and circuit arrangement for time division multiplex exchanges, in particular telephone exchanges - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: H 04 w German class: 21 a3-46 / 10

Number: 1177 213

File number: S 68880 VIII a / 21 a3

Filing date: June 10, 1960

Opening day: September 3, 1964

The invention relates to electronic, time division multiplexing switching systems, e.g. B. for telephone purposes. In such Systems are known to modulate the respective messages to be exchanged pulse trains, which are staggered in time and thus a multiple use of the connection paths allow. These pulse trains, hereinafter referred to as control pulses, are either the subscriber stations individually or are assigned to the established connections when the connection is established assigned.

The invention relates only to switching systems of the last type, which are characterized by the their peculiar assignment of the control pulses to the connections basically from the others Switching systems differentiate and therefore also in a completely different way in different sub-devices are structured. In these switching systems, as is known, the subscriber stations assigned electronic intercom switch, via which the subscriber lines to a so-called Speech multiplex point can be switched on. Due to the mutually offset pulse sequences, i.e. the phase-shifted ones Control pulses, only those speech switches are made permeable at the same time, which belong to those subscriber stations between which messages are to be exchanged. To control the speech switch, two circulating memories are provided, in which the addresses of the subscriber stations stored separately in coded form with outgoing and incoming traffic are. The addresses (these are characters individually assigned to each subscriber station) of each other connected subscriber stations occur in pulses and with the pulse repetition frequency of the control pulses repeated simultaneously at the outputs of the two circulating storage units; so they run into the Circulating accumulators with certain pulse phases cyclically. From there they get to facilities that are referred to as decoders and which, by evaluating these addresses, the speech switch make the assigned subscriber stations permeable. In this way connections are made maintained between the respective associated subscriber stations.

In order to establish these connections, the addresses of the subscriber stations involved must first be written into the relevant circular memory. The number of a subscriber station to be called is supplied by the respective calling subscriber station. According to the one-way method and circuit arrangement for time division multiplex exchanges,
in particular - telephone exchanges

Applicant:

Siemens & Halske Aktiengesellschaft,

Berlin and Munich,

Munich 2, Witteisbacherplatz 2

Named as inventor:

Dipl.-Ing. Max Schlichte, Munich,

Dipl.-Ing. Yew tree Siade Frers,

Dipl.-Phys. Dieter v. Sanden, Munich-Solln,

Dipl.-Ing. Edmund Ptacnik, Söcking,

Dipl.-Ing. Hans Dörfler, Munich

will periodically write the information entered from the storage device used for this purpose read out. On the basis of the reading, the control pulses occur which the subscriber stations Control assigned speech switch. Most often the subscriber station number becomes several Include digits that arrive individually or, under certain circumstances, in groups. With the known Switching systems dealt with here become the number of a called subscriber part corresponding digits are initially collected in special memories or registers until the relevant Participant number is complete. So there are special memories available here, their number the greater must be, the greater the number of subscriber stations connected to the system in question is. Each memory must be one and the same from the beginning of the number dialing to the end of it Be assigned to the participant's position. This collection of all belonging to a subscriber number Digits must be made because in these switching systems before the registered letter the subscriber number in the relevant circular memory is only determined by a free check must be whether the subscriber station identified by its subscriber number is free. But also if all digits belonging to a subscriber number from the calling subscriber station at the same time are delivered, special storage tanks are necessary because of the exemption. Would the other

409 659/97

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subscribers belonging to the subscriber station to be called - from subscriber stations with outgoing traffic and number or address prior to the free check - if the addresses of subscribers are written into the circular memory Ub, they would switch to the relevant locations with incoming traffic. The addresses that circulate in a circulating memory and the addresses belonging to this sub-connection each have the speech switch belonging to the subscriber station in a pulse-wise manner in the same circulating phase and are therefore made permeable at the same time. The requested connection would therefore be output at the outputs of the circulating buffers, because the connection would be established too early, since the outputs of the circulating buffers have not yet been determined whether the relevant subscriber-named decoders Da and Db are connected. Every vacancy is free. It is forbidden here because this decoder has as many outputs as the number of subscriber positions and the writing of individual digits in io len. Each of these outputs is assigned to a specific subscriber station immediately after the relevant circular memory. Everyone their arrival. For all these reasons, the speech switch must be provided both at an output and therefore the mentioned memory. That of the decoder Da is also connected to an output of the provision of the storage capacity decoder Db required here. Inserted OR-zity represents a considerable effort. 15 gates prevent mutual influencing. According to the invention, this effort is reduced by the decoder. When a decoder avoided the address. It enables only a single central station to be fed to a subscriber station, so a device is required which emits a relatively one pulse at the output to which this sub-compartment is constructed. The saving in effort is assigned to the employee position. This impulse becomes particularly large when a large number of controls of the subscriber stations assigned to this subscriber station are connected to the exchange. The invention uses speech switch. If, at the same time, a method for time-division multiplexing relates to two decoders at two different sub-exchanges, in particular telephony exchanges, subscriber stations assigned outputs in which the individual subscriber stations occur via impulse, then the two electronic sub-stations are phase-shifted by opposing one another Talk switch belonging to the subscriber stations and the respective connections associated with going closed, as a result of which these two part control pulses actuatable switches at a speaker station are switched on with one another at a multiplex point during this time and the control links are connected. This repeats itself periodically with the pulse with the participation of the addresses of call circulation period of the addresses circulating in the circulating memories and receiving addresses from called subscriber stations Addresses of the customer offices.

The subscriber stations involved in the connections In addition to those already described, the switches are also supplied. This procedure is facilities in place. Their tasks and characterized in that each of the characteristics provided by the calling subscriber station are then provided with the description of an example for that of a called subscriber station without prior writing of the address of a partial exemption to be called of the called subscriber station as the subscriber station. The subscriber at address should have immediately withdrawn into the circular memory for called subscriber station Tn 1. Which are stored by subscriber stations that DAR ₄₀ he dialed the by him aufhin the free examination of the called subscriber desired subscriber station, that is the number of a place to call is carried out and that only in freedom subscriber station, then meets at the called on the Sprechder subscriber station Due to the multiplex point SM, to which the receiving device's stored address from the circulating memory for MM is connected with its inputs, a control pulse is sent to the called subscriber stations. How this comes about with the phasing of the address of the called subscriber switching system shown here will be delivered later. described in more detail. It should be noted that it

Conveniently, this procedure is followed by other options out there to the chosen

Using a circuit arrangement carried out at subscriber numbers to the receiving device

the to get to the control of the called subscriber 50 MM , which with known

place assigned switch, the control pulse also applies to the switching system in question.

can be controlled via a further switch, only men are already shown. This includes B. the access

if the called subscriber station is free, the subscriber number is given via special

impulsively in the phase position of the network connected to which the subscriber loops.

Address linked control pulse is closed. The 55 arrived in setting MM sub-

In the following, this mentioned additional switch will be used without being saved here

referred to as a switch. after it has entered the circulating memory

In Fig. 1, the facilities of a Ub are schematically inscribed as an address. It is shown, as in the case of time-division multiplex telephony in question, the known, comparable systems with the mediation, which are to be entered in connection with the f> that circulating phase with which the method according to the invention is related. The subscriber stations Tn 1 to Tnx are connected to this address of the calling subscriber station in the UmVermittlung running memory Ua for subscriber stations with outgoing, which circulates via speech to be controlled traffic. Thereafter, an activation switch 51 to Sx can be pre- connected to the speech multiplex point SM test of the subscriber station to be called. The speech switches are used, e.g. B. in such a way that a check is carried out on the current addresses, controlled by control pulses, which, with the help of the circulating memories Ua and Ub, are already supplied by the circulating memories Ua and Ub. It will be for. In the circulating memory Ua , the addresses of this functional example initially assume that

the exemption test shows that the subscriber station to be called is free. The subscriber station to be called is z. B. the subscriber station Tnx. Because of their freedom, the desired connection can be established. So that this connection could not come about beforehand by writing the address of the subscriber station Tnx into the circular memory Ub , a special additional device is provided in this circular memory: Between

Address belonging subscriber station is assigned. This connection only exists as long as the delivery of the address lasts. During this time, however, a pulse is not yet emitted from the output concerned solely due to the 5 address delivery. The pulse source P supplying the control pulses of all pulse phases is now connected to the pulse feed input / of the decoder Db with the insertion of the through switch Sp 2 . At rest

The output of the circulation memory Ub and the de-IO state of the through switch Sp 2 do not reach the encoder Db , namely, the pulse to the pulse feed input / is still present. The through-switch switch Sp 1, which in the rest position, the connection Sp 2 is now interrupted in a manner corresponding to that between these two devices. Circuit example already described to the Um-Er can be closed in pulses, whereby it is connected to the current memory Ud , which when free during the supplied pulses, the output of the 15 of the subscriber station concerned pulses synchronously at the output of the circular memory Ub each with the output of their address from the Um appearing subscriber address to the decoder Db supplies running memory Ub . These impulses make the permit. The through switch Sp 1 is only then through switch Sp 2 during its presence with pulses for the output of the relevant partial permeable, so that the recipient address supplied by the pulse source P is supplied if it has resulted in 20 pulses to the relevant output of the decoder Participant position is free. It can also be long and delivered there. One can achieve several with further, independently of one another in this way, that the addresses supplied by the pulse source P of different circulating phase are output exactly in a prescribed one, so that several time rasters are present at the same time. The use of the special bonds can be maintained, namely 25 pulse source P therefore has the advantage that the maximum number of pulses provided by the decoder Db as many as the rotation phases, which the

Form speech switch controlling control pulses, are just as exactly in the prescribed time grid. Small temporal inaccuracies that can arise from the writing process of addresses in the circulating memory Ub, of pulses in the circulating memory Ud or the operation of the decoder Db are rendered harmless here by the use of the pulse source P.

The operating case will now be described in which the subscriber station to be called is already busy. In this case, the blocking switch Sp 1 and Sp 2 are not to be supplied with any closing pulses for the desired connection, and therefore there is also none

are. As has been shown above, the presence of the through switch Sp 1 makes it possible to save special buffers for storing the number of subscriber stations to be called.

To deliver the closing pulses required for the through switch Sp, an additional circulating memory is provided in the switching system shown here as an example. This is the one
Circulating storage Ud, in which the 35
calling subscriber station a pulse is entered in such a way that it circulates there with the same circulation phase as the address of the calling subscriber station in the circulating memory Ub . The through switch Sp 1 is also connected to the output of the additional pulse in the additional circulating memory Ud of a single circulating memory Ud ; and every- admit. As already mentioned, when the input pulse occurs at the output of the circulating memory Ud circulating in the circulating accumulators Ua and Ub , a pulse addresses are also checked for checking. It should be noted that delivered to the circuit breaker Sp 1. The latter, whether the address of the subscriber station to be called, provide pulses, the required closing pulses 45 are already circulating in this circulating memory. The zuudar. The additional circulating memory Ud can, for. B. calling subscriber station is only included as a free part of a delay element that is to be treated by a wire receiving station if its address is formed of a single suitable length, which in the given borrowed in the circulating memory Ub for subscriber stations with the case of one or more impulses circulates incoming traffic, and only as will. With the help of an address that causes the free test to belong to the circulating memory and as the amplifier circuit, after having arrived at the address supplied by such subscriber stations and at the end of the wire, they can already receive the busy signal again at the arrival. The free catch of the wire is fed in, which results in the test initiating address War just before a periodic cycle of the impulses. Free test inscribed in the circulating memory Ub

The above-described insertion of the to 55 ben and therefore circulates there. Most of the time, the through switch used will only stand once in the circulating memory Ub transition of the circulating memory Ub and the input of the between the output. However, it can also be the case that a decoder Db is one of various possibilities that the subscriber station to be called has the ability to insert it. Another example of this from another subscriber station is shown in FIG. Initially 60 was requested, but was occupied. This subscriber station calling for the operating mode of the decoder Db used here is therefore given the busy status. This decoder also has the partial symbols. The outputs assigned to the subscriber stations as a result of this connection request and the written address can still be circulated in the circular input via which the subscriber addresses are also circulated. In the meantime, the requested can still be fed to the pulse feed input /. When 65 subscribers have finished their conversation and their subscriber station has been assigned a subscriber address to the decoder can therefore be free so that the subscriber station is temporarily connected to the pulse feed last requested connection input / with the output that can be used. Addresses from such subscriber locations

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were delivered, which can then hear the busy signal. You can do this in the form of multiple stops, therefore do not mean that the frequency code character to be called is occupied by the subscriber stations. The part to be called is delivered, that is, in the form of characters, the receiving station is therefore also free if its address has a characteristic number of tone frequencies that are different from the reasons described above. The character memory Ub circulates. can then over the speech cores and the speech memories Ua and Ub belonging to the address check at the respective subscriber station, the circulating switch up to the speech multiplex point SM must be delivered addresses with the address of the calling part. As well as the number of the calling subscriber station are compared. This can e.g. B. done with io subcontractor in the circulating storage Ua -the help of so-called comparators. This is because this participant is shown in FIG. The switching system shown in FIG. 1 are present via their speech switch with the aid of one of the two comparators Va and Vb . Control pulse pulse-wise with the speech multiplex furthermore an address register G is provided. point SM connected. This begins even before this central subscriber station, which is only available once, delivers voting information. Facilities. Synchronous with the impulses of this subscriber. For a comparison process, the control pulse assigned to a point is sufficient, then the transfer device MM present in the circulating memories is sufficient with the speech multiplex time span. During this period of time, the Punkt has to connect so that it can receive the multi-frequency address of the subscriber station to be called in code characters as well. Address register G can also be used. The comparators Va be that not just one, but several partial and Vb are also supplied with the outputs of the receiving stations multi-frequency code characters, circulating memories Ua and Ub as well as with the address because they request a connection at the same time, senregister G via special Lines connected. The transmission device MM therefore has several If an address equality occurs, this will be 35 inputs, which can be connected to the central control device E via lines leading to the speech multiplex point SM , independently of one another, in pulses from the comparators Va and Vb. Special electronic ones are reported for this. In the control device E these switches are provided, which are evaluated in Fig. 2 with z \ to zi messages, whereupon are denoted in the given. The inputs belonging to them fall with their help, a pulse is timely entered in the feed to the digit receivers Zl to Zi, to additional circular memory Ud . which the various Mehrfrequenzkodezeichen, The central controller £ serves also without that they overlap each other, pass, for controlling the various in the intermediary The electronic switches ζ 1 to zi Namely lung system settled exchange operations. controlled by pulses, which, just like the ver-You is therefore connected to the establishment of the system via 35 different subscriber stations assigned control lines, among other things are also phase-shifted with the pulse. With transmission device MM. The arrows drawn in the lines Help of the other parts of the transmission device each indicate in which MM the incoming characters will then be directed to the direction via these lines messages, control circulating memory Ub with the assistance of the control commands, etc. With the help of this control device E forwarded. A storage of the device can also delete the addresses Hch which are circulating in the characters is not required in this context- circular memories Ua and Ub.

as well as from circulating in the circulating memory Ud , a system of multi-frequency pulses can be used. Such deletion code characters, which are to be linked to a code that can be monitored for correctness, in particular when separating connections of the incoming characters. The settlement of this is formed, for. B. after one of the above processes, however, does not belong to the invention and a 2-out-of-5 code, the monitoring for the is therefore not described in more detail here. Correctness of the incoming characters equal to As already mentioned, a subscriber number when it arrives in the transmission device MM generally consists of several digits. The 5 ° can be made. The transmission device for writing a subscriber number can MM then also carry out a code check, according to the method according to the invention, incorrect characters will also be carried out on the basis of the control if the subscriber number is not forwarded. Correct characters can be recoded under or groups of digits before they are forwarded in the form of digits supplied one after the other. The digits or 55 are thrown. The characters that can belong to a control digit group without disturbances can be resolved code must namely have a certain redundancy immediately after their arrival in the relevant redundancy. After the control, this is to be written into the circular memory. Redundancy is superfluous and also disadvantageous, since the intermediate storage of individual digits or digits - these characters save a larger than the non-grouped ones, until the entire subscriber number is primarily required, is not necessary because here the free check of the available memory, here the circulating memory Ub, the subscriber station to be called only after the input is required. It is therefore appropriate, before writing the subscriber number in circulation to write to the circulating memory Ub still gespeicher Ub is to be made. to carry out suitable recoding. Both the code control and the recoding are described in which way the digits or further processing of the groups of digits provided by the subscriber in question are provided by the subscriber station. A storage of these characters to reach the receiving device MM is not necessary here either.

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FIG. 3 shows an example of how the in is reached via the rectifier 392 to the terminal 2D

Fig. 2 schematically shown arrangement in and via the rectifier 393 to the terminal 3D.

can be built up individually. It also comes from terminal 331 via the equal

The decoder Db has seven output terminals ID rectifier 394, 395, 396 and 397 to the terminals 4 D, to ID, and it can therefore use seven 5 SD, 6 D and ID. If z. B. can be controlled at the terminals speech switch. The input terminal pairs 311/312, 321/322 and 331/332 cannot be controlled via the rectifier 391. Via these input terminals, more like the ground potential to terminal 1 D before, the addresses of subscriber stations will be in the form. Instead, acts there via the re-supplied by binary code characters. Each binary code stood 333 at the negative potential - U. The symbol consists of three elements; from terminals ID to ID , on the other hand, the ground potential of one input terminal pair is retained as it is routed from terminals 321 and 331. A drawing element can either get there in the same way as before. Due to the presence of earth potential in the speaking way, a negative potential occurs at one of the clamps 2D belonging to a clamp pair, clamp 15 to ID , if one of the and negative potential is applied to the other associated binary code characters,
other terminal or by the fact that the negative potential occurring at the terminals ID to ID these potentials against each other at the two terminals is now exchanged for the control switch. In the idle state, the speech switch is used on the rung. The decoder described here be input terminals 311, 321 and 331 ground potential 20 can control seven speech switches and at the input terminals 312, 322 and 332. It can now be made using a manegative potential. This potential distribution ent- trix of rectifiers, which is more extensive than that speaks the binary code character 000 can control more intercom switches.
Binary code characters LLL etc. depending on which The circular memory Ub supplies the addresses, the binary code characters are to be fed to the input terminal pairs to the decoder Db. The circulation is carried out, one of the terminals ID to ID memory Dc contains the same delay elements, marked by the negative potential - U occurring - in the periodically circulating pulses entered there. Only if the binary code character 000 can be supplied. In Fig. 3 is one of these run times, none of the terminals ID to ID are marked. elements, namely the delay element UbI, in detail The decoder Db consists of a matrix with equals. It contains the wire 351, which such judges. The column lines (perpendicular) of this length have that a magneto-matrix at one end is reached by the terminal /, as initially entered impulsively, the other end of the wire via the resistors 333, 35 if the time interval 334, 335, etc., the potential - U is supplied. The two pulses of a control pulse has elapsed. Row lines (horizontally) of the matrix are paired The wire is combined at both ends by suitable evidence and each clamped to an input fastening means 353 and 354 in such a way that a pair of terminals is assigned; so is the first line - there no reflections of pulses occur. With a pair of wires to the input terminal pair 311/312 40 with the aid of the coil 352, pulses can be connected to the wire; the second row wire pair can be entered at 351. When a pair of input terminals 321/322 and the third current impulse are sent through this coil, - a magnetic field is created, the row wire pair is connected to the input terminal pair which shortens the wire 331/332 in the longitudinal direction. As mentioned earlier, lies in or extended. This change in length then runs through the idle state at the terminals 311, 321 and 331 45 as a pulse on the wire, namely in the longitudinal direction-earth potential and at the terminals 312, 322 and 332 device. The wire consists of a ferromagnetic negative potential. The column lines of the matrix material, e.g. B. Nickel. One end of the coil is connected to the seven terminals ID to 7 D via the collector-emitter path of the pnp trans. The rectifier bridge crossing points sistor 355 to ground potential and the other end of row lines and column lines and are 50 of this coil is via the resistor 357 and the so distributed and polarized so that if at least collector-emitter path of the pnp transistor 356 at least one pair of input terminals which are connected to the potential - U. The base of the Trand potentials are interchanged, one of the sistors 356 is via the resistor 358 under the terminals ID to 7 D negative potential occurs. Influence of earth potential, so that this transistor is previously earth potential at these terminals. When 55 is normally conductive. The base of the transistor is now the input terminal pairs binary code characters 355 via the resistor 360 under the feed, so each at least flow of the positive potential + Uv, so that this one input terminal pair, the Po transistor lying there is normally blocked. In addition, potentials are interchanged. Therefore, the base of this transistor occurs in each case via the resistor 359 at one of the terminals ID to 7 D negative potential 60 connected to the terminal 311. When on this one. In total there are seven different here in terminal a negative impulse occurs, so the question is coming binary code characters. Transistor 355 temporarily conductive, so that the

As already stated, a current surge is flowing through coil 352 in the idle state,

terminals 311, 321 and 331 earth potential. This causes a pulse to be fed into wire 351.

Earth potential also has an effect on the 65 at rest. The resistor 357 is used for limiting

Terminals ID to 7 D off. From terminal 311 the current strength.

that is, when the earth potential reaches the rectifier, there can be two different reasons

ter391 to terminal ID, from terminal 321 to terminal 311 negative pulses occur. Of the-

like pulses can initially be generated with the aid of transistor 361. The emitter of this transistor is connected to terminal 311. Its collector is at the potential - U, and its base is under the influence of earth potential via the resistor 362. This transistor is therefore blocked in the idle state. If a negative pulse is applied to its base via terminal Eb 1 and resistor 363, the transistor becomes temporarily conductive and a negative pulse therefore also occurs at terminal 311, which then causes a pulse to pass through wire 351 . Via the terminals Eb 2 and Eb 3 , pulses can be input into the delay elements Ub2 and Ub3 in a corresponding manner. The terminals Eb 1, Eb 2 and Eb 3 represent the inputs of the circulating memory Ob , via which the addresses for circulation can be entered.

At the end of the wire 351 is the coil 364. When the pulse inputted into the wire passes it, a voltage surge is induced in it. The base of transistor 366 is now connected to this coil. With the help of the resistors 367 and 368 lying between the ground potential and the negative potential - U, it is achieved that the base of the transistor 366 has a potential such that it is conductive in the idle state. The coil 364 has such a winding sense that, in the given case, a positive pulse is fed through it to the base, so that the transistor 366 is temporarily blocked. The collector of the transistor 366 is connected to the negative potential - U via the resistor 370. The emitter of this transistor is connected to ground potential. Terminal 311 is also connected to its collector. When the transistor is in the quiescent state, i.e. when it is conducting, this terminal 311 also has the earth potential. If, on the other hand, the transistor is blocked, the negative potential - U acts on terminal 311 via resistor 370. This is the case when a pulse previously input into wire 351 passes coil 364. This pulse is therefore re-entered into wire 351 at this moment through the cooperation of transistors 366 and 355. It therefore runs through it periodically.

An address circulating in the circular memory can also consist of more than one pulse. Each pulse circulates periodically in a different delay element. These impulses are entered into the delay elements with the same circulation phase. It must now also be ensured that they always continue to circulate with the same phase of rotation. To make this possible, a synchronization device is provided which consists of the pulse generator P which is connected to terminals 311, 321 and 331 via a rectifier. The rectifier 371 leads to terminal 311. The pulse generator supplies negative pulses, the spacing of which is equal to the spacing between the successive pulses and the pulses passing through the delay elements. The internal resistance of the pulse generator P is very small. During the pulse pauses, terminal 311 is therefore at ground potential via the rectifier 371 and the internal resistance of the pulse generator P. A negative pulse can only occur at terminal 311 when transistor 366 is blocked and when, in addition, pulse generator P is currently delivering a negative pulse. If only transistor 366 is blocked, the negative potential - U on resistor 370 cannot have any effect on terminal 311, since this is connected to earth via rectifier 371 and the very small internal resistance of the pulse generator. If only the pulse generator P supplies a negative pulse, the rectifier 371 is loaded in the reverse direction. One of those

ίο negative impulse cannot be applied to terminal 311 impact.

The addresses circulating in the circular memories can be deleted again. For this purpose, the transistor 356 is used in the delay element Ub 1. This transistor is conductive in the idle state. If the terminal LbI is supplied with a sufficiently negative pulse, it is blocked. A pulse to be rewritten in the wire 351 at this moment is thereby suppressed and

ao therefore deleted. In a corresponding manner, pulses circulating in the delay elements Ub2 and Ub3 are deleted.

The supply of potentials to terminals 311, 321 and 331 was described above. However, suitable potentials must also be applied to terminals 312, 322, 332. In the idle state, the potential - U via resistor 373 affects terminal 312, for example. If a negative potential occurs at the terminal 311, the transistor 372, which has been blocked until then, is made conductive via the resistor 374. The collector of this transistor is connected to terminal 312. Its emitter is at ground potential. If the transistor 372 becomes conductive, then ground potential is therefore also applied to the terminal 312. There is therefore either negative potential or earth potential at this terminal. In the given case, the required interchanging of the potentials at terminals 311 and 312 occurs. The circuit with the transistor 372 thus serves as an inverter. Terminals 322 and 332 are supplied with potentials in the same way as terminal 212.

The input terminal pairs of the decoder Db are supplied with the provided potentials by the circulating memory Ub. So far it has been assumed that the constant negative potential - U is applied to the terminal / of the decoder Db. Instead, negative pulses, which are supplied by the pulse generator P , can also be supplied there. This ensures that the control pulses delivered by the decoder have exactly the correct phase position.

An electronic switch Sp 2 is now inserted into the connecting line leading from the pulse generator P to the terminal /. It is controlled by the circulating accumulator Ud via the terminal Ad with the aid of negative pulses. It consists of rectifiers 382 to 385 and transformer 386.

Due to the voltage of the voltage source 381, which is connected in series with the secondary winding of the transformer 386, the rectifiers are stressed in the reverse direction when the electronic switch is in the idle state. In this state of the switch Sp 2 , therefore, no pulses can pass from the pulse generator P to the decoder Db , since the mentioned rectifiers are inserted in the connecting line between them. The ones from

Negative pulses supplied to the circulating memory Ub are fed to the primary winding of the transformer 386 and also produce pulses in the secondary windings. If the windings of the transformer have a suitable winding sense, the pulses occurring in the secondary winding have such a polarity that the rectifiers are stressed in the forward direction under their influence. During the presence of such a pulse, pulses supplied by the pulse generator P are therefore fed to the terminal /. The circulating memory Ud _1, which supplies the pulses controlling the electronic switch SF »2, is constructed in exactly the same way as the delay element UbI. It should be noted here that the speech switches Sl to Sx can be constructed in exactly the same way as the electronic switch Sp 2 .

In the circuits according to FIG. 1, the electronic switch Sp 1 is provided, which is inserted between the circulating memory Ub and the decoder Db. This switch can also be used in the case of the FIG. 3 can be provided in place of the switch Sp 2 . Electronic switches must then be inserted in the lines arriving at terminal pairs 311/312, 321/322 and 331/332. These switches are shown in FIG. 3 indicated and labeled Sp 11, Sp 12 and 5p 13. They can be constructed in exactly the same way as switch Sp 2. When using switches Sp 11 to Sp 13, the constant negative potential - U must be applied to terminal /.

Claims (9)

Claims: 35 1. Method for time-division multiplex exchanges, in particular telephone exchanges, in which the individual subscriber stations are connected to a speech multiplex point via electronic switches that can be actuated by control pulses that are out of phase with one another and assigned to the respective connections, and the control pulses with the assistance of the addresses of calling and called subscriber stations receiving separate circulating storage units are supplied to the switches in accordance with the addresses of the subscriber stations involved in the connections that are cyclically circulating in these, characterized in that the identifiers of a called subscriber station (Tnx) supplied by a calling subscriber station (7nl) without prior verification of the called subscriber station (Tnx) are immediately stored as an address in the circular memory (Ub) for called subscriber stations, so that the free check of the called subscriber station (Tnx) is then carried out and that only when the called subscriber station (Tnx) is free, based on the stored address from the circular memory (Ub) for called subscriber stations, a control pulse in the phase position of the address of the called subscriber station (Tnx) is delivered. 2. Circuit arrangement for carrying out the method according to claim 1, characterized in that the control pulse supplied to control the switch (Sx) assigned to the called subscriber station (Tnx) can be controlled via a further switch (Sp 1 or Sp 2) which is only available when Freedom of the called subscriber station (Tnx) is closed in each case pulse-wise in the phase position of the control pulse linked to its address. 3. Circuit arrangement according to claim 2, characterized in that the further switch (Sp 1) is connected downstream of the circular memory (UB) for incoming traffic subscriber stations and forwards the addresses output by this circular memory (Ub) for the delivery of control pulses. 4. Circuit arrangement according to claim 2, characterized in that a decoder (Db) is connected to the circulating memory (Ub) for subscriber stations with incoming traffic, which has outputs assigned to the subscriber stations and a pulse feed input (/) and which has this pulse feed input when an address is supplied (/) connects temporarily to the output that is assigned to the subscriber station belonging to the address, and that a further switch (SpI) is inserted between this pulse feed input (/) and a plus source (F) supplying the control pulses of all pulse phases. 5. Circuit arrangement according to claim 3 or 4, characterized in that an additional circulating memory (Ud) is provided, in which when the subscriber stations to be called (Tnx) are free, a pulse is entered in such a way that it is there with the same circulating phase as the address to be called Subscriber station in the relevant circulating memory (Ub) circulates, whereupon the required closing pulses are supplied from the output of the additional circulating memory (Ud) to the further switch (Sp 1, Sp 2). 6. Circuit arrangement according to one of claims 2 to 5, characterized in that for checking the subscriber station to be called it is determined whether its address is already circulating in those circulating memories (Ua, Ub) in which the addresses assigned to the connections circulate, and that the address to be called Subscriber station (Tnx) is only treated as a free subscriber station if its address either does not circulate in any circular memory or only circulates in the circular memory (Ub) for subscriber stations with incoming traffic, namely only as the address that initiated the free check and as the address supplied by such subscriber stations, who have already received the busy signal. 7. Circuit arrangement according to one of claims 2 to 6, characterized in that the subscriber number arrives in the form of digits or groups of digits supplied one after the other, which are individually written into the relevant circular memory (Ub) when they arrive. 8. A circuit arrangement according to claim 7, characterized in that the digits or groups of digits are supplied in the form of multi-frequency code characters from the subscriber stations (Γη 1 to Tnx) , which are synchronized with the pulses of the control pulses assigned to them via the speech multiplex point (SM) a receiving device (MM) are connected. 9. Circuit arrangement according to claim 8, characterized in that the digits or groups of digits are written with the assistance of the receiving device (MM) , in which they are subjected to a code control and in which a recoding into a ben particularly suitable form is made. Documents considered: German Patent No. 922 722; German patent application T 7491 VIII a / 21 a ³ (published May 6, 1954);
Ericsson, Review, 1/1956, pp. 13-14. 1 sheet of drawings 409 659/97 8.64 © Bundesdruckerei Berlin