DE1903607B1 - Circuit arrangement for a time division multiplex switching system, in particular for a PCM time division multiplex telecommunications system - Google Patents

Description

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The invention described below relates to time division multiplex telecommunications systems of importance to the

make use of a circuit arrangement for time division multiplexing from PCM technology. The PCM

Switching systems, d. H. on switching systems, technology itself is relatively insensitive to interference;

where the between the individual, from case to case, however, a pulse code modulation is generally

In the case of interconnected end points, each of 5 to begin with, a pulse amplitude modulation

transmitted information pulse sequences on mod- ahead, and thus the crosstalk attenuation is

which are staggered in time, especially with regard to a subsequent

and therefore attached to one of the PCM operation by nesting.

Multiplex rail can be bundled in time. The invention relates to a circuit arrangement

In order to provide such a pulse modulation and bundling in advance for time division multiplex switching systems with a

to be able to take or the modulated and temporally plurality of subscriber line groups, their

bundled pulse trains to be able to separate from each other- respective two-wire connection lines with their respective

nen, so-called time filters are used; such a line core via a single-pole one

The time filter basically consists of a participant time channel switch connected to one wire of the associated

individual switch (time channel switch) that can be switched on in this way and with

is controlled so that it is in phase with one of the other line wires firmly to the other

Sampling theorem sufficient period pulse-wise lei- wire of the two-wire multiplex bus connected

tet. Connections between two subscriber line and their two-wire multiplex rails with the help

lines of a multi-stage time division multiplex switch of crosspoint switches via multiplex intermediate

management system can be connected to one another by simultaneous actuation in ao lines, in particular

Question of upcoming crosspoint switches for PCM time division multiplex systems; this time division

brought. Switching system is according to the invention thereby

In such time division multiplex switching systems, it is identified that there is a two-pole coupling the risk that between more or less point switches are provided over each of the adjacent transmission channels one more or one core of a two-wire multiplex rail with the there is less crosstalk. One wire of a multiplex intermediate line and the it is z. B. to crosstalk between the other wire of the two-wire multiplex rail with the Transmission channels of the same spatial, but inter alia wire of the multiplex intermediate line more connecting act timely. Measures to the bar is, and that the said other veins of the Reduction of such crosstalk is known about 30 two-wire multiplex bars each via one (see e.g. German Auslegeschrift 1278 496); a resistor whose resistance value is large should not be pursued further here. The invention of one such other vein This application deals with the crosstalk between multiplexed links, with earth or ground such transmission channels of a time division multiplex connection is connected.

mediation system that differs in its spatial, not in 35 The invention brings the advantage of a to a differentiate their temporal position; such time multi-noticeable crosstalk attenuation at practical pelx transmission channels of the same time slot can only be found leading to constant throughput loss in multi-level switching systems, their connection pulse-wise switching through of the return current lines each with a separate multiplex track, in the form of a »pseudo symmetry, so to speak who see the associated connecting lines with the help of 40 'through-connection with themselves, which are only their time channel switch are connectable, have on the connecting the individual line trunk groups the subscriber line groups are the switching network part of the time division multiplex switches, whose multiplex rails in turn need to extend with the help of the system, whose crosspoint crosspoint switches Only about 25% of the number of subscribers can be connected to one another via the number of multiplex intermediate lines. Such a 45 individual time channel switch will be. Included Crosstalk between time division multiplex transmissions is advantageous in that the channels in the return flow path are too shallow The same time slot can be extremely small because of galvanic tend voltages Couplings between the channels caused by the resistances mentioned the use of identical conduction caused discharge noticeable charges of the parts, in particular through common power return 50 named other wires during the switching pauses tion over earth or mass, can be conditional. cannot come about. Advantageously In principle, such crosstalk could therefore, according to a further embodiment of the invention a consistently earth- or mass-symmetrical connection each of the one core of a two-wire multi-connection through-connection be avoided, in the case of a plex rail with one wire of a multiplexer, that is, all connections via individual line 55 intermediate lines connecting one crosspoint wire pairs be guided. Such a measure would contact a two-pole crosspoint but very expensive, especially on switches as a symmetrical diode bridge circuit the side of the subscribers present in large numbers and the other, the other wire mer connection lines, where this symmetrical deep or two-wire multiplex rail with the other wire Matching and two-pole time channel switches 60 connecting the multiplex link would have to be provided. point contact as an anti-parallel connection of two diode

The invention now shows a way in which multiple transformer series circuits can be constructed. this Stepped time-division switching system an ancillary brings on the one hand the advantage of only little speech of the last-mentioned type very costly for the pulsed connection of the rend to be able to dampen. Such a crosstalk 65 return current path with it and, on the other hand, also leads Attenuation is not only for time-division multiplex remote control to attenuation of a capacitive coupling alarm system, the crosstalk between time multi-amplitude modulation brought about solely on the basis of a pulse work, but also for plex transmission channels of the same time slot that on

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a voltage division between the diode barrier wire multiplex rail, in the example the wire MS Ib

capacity and the winding capacity of the control of the multiplex bus MS1, with the other wire of the

winding of the diode bridge is based on the multiplex intermediate line, in the example with the

the effects of the capacitance of the wire Nb of the multiplex intermediate line N, connectable. Crosspoint switch evoked capacitive 5 The other wires mentioned MS Ib .. .MSnb der

Coupling of the multiplex notes accordingly. Two-wire multiplex rails MS ¹ I. .. MSn are each

be dropped off; be discontinued; be deducted; be dismissed. because via its own resistor R with earth resp.

With reference to the drawings, the invention is still connected to ground; the resistance value of such

explained in more detail. Resistance R is large compared to that

F i g. 1 shows schematically a according to the invention io one of the said other cores Ib ... Nb of

established time division switching system; Multiplex intermediate lines I .. .N. It will be here-

2 shows circuit details achieved by the fact that, when a club is switched through according to the invention, the coupling connection between two two-wire multiplex rails, point switch. for example between the multiplex rail MS1

The in F i g. 1 only in one for understanding 15 and the multiplex rail MSn, represented by synchronous scope required by the invention, the multi-stage time division multiplex switching system in question contains the multiplex rails concerned with one and the same multiplex link, initially a plurality of subscribers, for example the multiplex link N, connecting groups AGl. .. AGn; Each of these connecting crosspoint switches, in the example the connection groups, comprises a plurality of connecting lines Al nbkbN leading to partial crosspoint switches and nakaN / recipients or the like, the return flow essentially via the and a two-wire time division multiplex rail MS1 mentioned other wire (Nb) of the relevant Multi -... MSn, with which the connecting line or ground combined via the ground connection group flows through this to such a plex intermediate line (N) , since between this and the common Al means Connection line-individual time channel- 25 seed base of the individual connection lines Al switch ZS periodically, impulsively, in each case to a pulse phase assigned to the respective connection group representing the respective connection called another wire (MSlö or MSnb) which can be connected. In this case, the mentioned resistor R is inserted in each case via the single-pole respective two-wire multiplex rail (MS1 or formed time channel switch ZS which has one line MSn). Here vein of the relevant two-wire connection line Al 30 is with a relatively small resistance of z. B. to one wire (MSIa ... MSna) of the associated 20 ohms with an approximately 5 ohms resistor two-wire multiplex rail (MSl ... MSn) switch-on status value of the other wire (Nb) mentioned one bar, while the other line conductor of the multiplex intermediate line (N) between two - beibetreffenden two-wire connection line AI firmly to the game by way of the multiplex intermediate lines and / or other cores (MSIB ... MSNB) of the respective 35 and N extending - reasonable time-division multiplex transmission two-wire multiplex rail (. MSl .. MSn) channels of the same Time slot has already closed a considerable amount. The two-wire multiplex rails MSl increase the crosstalk attenuation by z. B. more .. .MSη are achieved via multiplex intermediate lines / .. .N, than 20 db, while on the other hand the throughput attenuation in Fig. 1 as preferably equal to each other compared to ratios such as in long sections of existing coaxial lines only single-pole through-connection with the omission of the provided, resistors R would be given with the help of crosspoint switches, at most insignificantly connectable to one another. In Fig. 1 is so that Hch is increased, on the other hand, compared to ratios such as the time division multiplex rail MS ¹ 2 shown there with single-pole through-connection while maintaining no subscriber lines, nor would there be resistances R , it means that there is a such time division multiplexing 45 Hch by about 14 db, is lower. track MS 2 also by a time-division multiplex connects Due to the can extending extension line acting through the resistors R, which leads to another the connection of the base points of the group as time division switching system or by the single connecting lines Al are herführt zudort, in particular also by a time multi- -. equal appreciable boots Anschlußplexverbindungsleitung this, in the case, without this being 5 ° group-base points, the wires MSIB .. .MSnb ie in Figure 1 shown in more detail, nor a two-wire multiplex rails MSl ... MSn, currency PAM -PCM coder or decoder can be inserted. rend of the switching pauses prevented. For the same reason, the outer conductors of the multiplex intermediate multiplex lines I .. .N shown in FIG. 1 as wire multiplex rails MS1 ... MSn and the coaxial lines are now two lines I .. .N W is connected to earth or ground via cross-point switches laka I / l bkb I with opposite poles , the resistance values of -... nakaNInbkbN provided. Over the one head, for example, can have 500 ohms. Hence pelpunktkontakt of such a crosspoint switch, a result, in the current return path, that of the example via the coupling point contact lakan crosspoint contacts lbkb I. .. nbkbN to schaldes crosspoint switch lakaNIlbkbN, 60 Tenden voltages are extremely small, respectively, so that one wire of a two-wire multiplex rail, both that the crosspoint contacts 1 bkb I .. .nbkbN corresponding to the wire MSla of the two-wire multiplex-speaking can be simply constructed, rail MS1, with the one wire of a multiplex Fig. 2 shows another example of an intermediate line, in the example with the wire Na the for a circuit implementation of a two-multiplex intermediate line N, connectable; over the 65 pole formed crosspoint switch Lakani other coupling point contact of the respective coupling lbkb N. Referring to FIG. 2, the one wire MSl a point switch, in the example the Koppelpunktkon- a two-wire multiplex rail MSl with a clock 1 bkbN, the other wire is of the relevant Two-wire N α of a multiplex intermediate line N connects

The one crosspoint contact la ka N of the two-pole crosspoint switch is designed as a symmetrical diode bridge circuit, as is known in principle (see, for example, German patent 1146129). The other one wire MSl & the two-wire multiplex rail MSl with the other wire N of the multiplex intermediate line N connecting the coupling point contact lbkbN is (known per se also in principle, see, e.g., German Auslegeschrift 1 263 859th) as an anti-parallel circuit of two diodes - transducer - formed series circuits, Here, under the prerequisite that a voltage drop occurring across one of the resistors R (see FIG. 1) is sufficiently small, a special bias of the diodes can be dispensed with. The switching pulse power required for the coupling point contact lbkbN is so low that a separate pulse source is not required; like F i g. 2 shows, it is sufficient to control the diodes with the help of an additional push-pull winding via the same transformer, which is also used to control the cross- point contact lakaN , which is implemented by a symmetrical diode bridge with biased diodes.

Claims (2)

Claims: 25 1. Circuit arrangement for a time division multiplex switching system with a plurality of subscriber line groups whose respective two-wire connection lines can be connected to one wire of the associated two-wire multiplex rail with their respective two-wire connection lines via a single-pole time channel switch and with their respective other line wire firmly connected to the other wire of the two-wire multiplex rail and whose two-wire multiplex rails can be connected to one another with the help of cross-point switches via multiplex intermediate lines, in particular for PCM time-division multiplex systems, characterized in that two-pole cross-point switches (lakal / lbkbl ... nakaN / nbkbN) are provided via which one wire (MSIa. .MSna) a two-wire multiplex rail (MSl) ... MSn) with one wire (Ia .. .N a) a multiplex intermediate line (I .. .N) and the other wire (MSIb .. .MSnb) of the two-wire multiplex rail (MSl ... MSn) with the other wire ( Ib .. .Nb) of the multiplex intermediate line (I ... N) can be connected, and that the named other wires (MSIb ... MSnb) of the two-wire multiplex busbars (MSl ... MSn) each have their own resistor (R), the resistance of which is large compared to that of such other wire (Ib ... Nb) of a multiplex intermediate line (I ... N) is connected to earth or ground. M. 2. Circuit arrangement according to claim 1, characterized in that the one wire (MSIa) of a two-wire multiplex rail (MSl) with the one wire (Na) of a multiplex intermediate line (N) connecting a crosspoint contact (lakaN) of a two-pole crosspoint switch (lakaNllbkbN ) is designed as a symmetrical diode bridge circuit and the other cross-point contact (lbkbN) connecting the other wire (MSIb) of the two-wire multiplex rail (MSl) with the other wire (Nb) of the multiplex intermediate line (N ) is designed as an anti-parallel connection of two diode-transformer series circuits. 1 sheet of drawings