DE1512844C3 - Time division multiplex switching system, in particular time division multiplex telephone branch exchange switching system - Google Patents

Description

The invention relates to a time division multiplex switching system, in particular a time division telephone extension - Switching system, for subscriber lines that connect with each other in local traffic and with trunk lines in long-distance traffic are and with insurers.

Time division switching systems of the known type often use the resonance transmission principle to get information, e.g. B. speech streams in the form of time-staggered, amplitude-modulated pulses between selectable lines via common connection means, so-called multiplex points or Time division multiplex rails to lead (see, for example, "Nachrichtenentechnische Zeitschrift" 1957, Issue 7, pp. 339,340). Despite short pulses and long repetition periods, transmission losses can almost completely avoided and the connections are made without amplifiers and therefore two-wire. For long-distance traffic, however, the losses essentially fall for the direct current / alternating current separation necessary transformer heavy in weight, 'so that to comply with the damping conditions the use of low-loss and therefore large transformers is necessary. Since every line also has one requires such a transmitter, there is a relatively large effort. For connections in Local traffic is very often the condition that a certain level reduction must be present, so that there are not too great differences in level between local and long-distance traffic. The necessary Attenuators mean additional expense, especially in time-division multiplex telephone exchanges, because they must be available for each subscriber line.

From the DT-AS 1167910 is a time division multiplex switching system known with a four-wire multiplex rail, in which both connections between the individual connections of the switching system as well as connections between connections, which belong to various such switching systems, can be switched four-wire. For this the four-wire multiplex rail consists of two four-wire-like sub-rails, of which the one for incoming traffic and the other for outgoing traffic, whereby the speech

The energy-absorbing part of a partial rail is connected to the speech energy-emitting part of the other partial rail via a first controllable amplifier and the speech energy-emitting part of one partial rail is connected to the speech energy-absorbing part of the other partial rail via a second controllable amplifier. In this case, each of the two controllable amplifiers is controlled in amplification during each speech phase by a control signal corresponding to the line attenuation of the connected connection line.
"From the DT-AS 12 27 078 a circuit arrangement for the pulsed transmission of messages in time division multiplex telecommunication switching systems is known, in which two multiplex rails are connected to one another by means of an amplifier device and each connecting line has access to each of the two multiplex rails via a switch A single pulse phase is used, whereby only outgoing connection lines are connected to one multiplex rail and only incoming connection lines are connected to the other multiplex rail only the receiving branches of the respective connecting lines are connected to the other multiplex rail.

In all of these known systems, the amplifiers are used for both local transport connections as well as for long-distance connections, so that, if you don't want too large level differences in Take purchase, the amplifiers used must be controllable in terms of gain. Such However, amplifiers are very expensive, especially if their amplification factor is briefly out of the pulse phase must be changeable to pulse phase.

In a time division multiplex switching system of the type mentioned, the invention solves the problem of the arbitrary interconnection of connection lines of local and long-distance traffic with activation predetermined damping conditions with less technical effort than with known ones To enable arrangements.

This object is achieved in that each subscriber line has two wires over a lossy one Subscriber circuit and a downstream resonance transmission device to a first time division multiplex rail can be switched on during the closing period of the associated subscriber switch, which first time division multiplex rail for wide area traffic during the closure period of the associated subscriber counter one after the other first via a first pulse amplifier and a first in series Switch to the transmission branch and then via a second pulse amplifier and one in series with it second switch to the receiving branch of a second time division multiplex bus provided with line circuits for the connection of exchange lines can be switched on.

The structure according to the invention of a time division multiplex switching system enables any in a particularly simple manner and with little effort Interconnection of any two connecting lines from all connecting lines of the local and long-distance traffic in just one pulse phase of local traffic while observing specified damping conditions, d. H. an attenuation of the call level in interconnected connections of local traffic and a reduction in attenuation in the case of interconnections with long-distance connections. With this structure a Time division multiplexing the attenuation of the connections in local traffic from for example to 0.7 or 1.2 neper without additional effort in the subscriber circuits due to smaller than usual dimensions and thereby realizing transformers afflicted with greater losses. For connections In long-haul traffic, the attenuation can be compensated for by the amplification factor of the pulse amplifier and, for example, lower it to below 0.1 Neper. There are only two amplifiers in total are required, but on the other hand a transmitter is required in each subscriber circuit, results a considerable saving.

The invention will now be explained in more detail, for example, with reference to the drawings. 1 shows the structure of a time division multiplex switching system, insofar as this is necessary to explain the structure according to the invention, FIG. 2 level curves of the level profile for connections in local and long-distance traffic, F i g. 3 pulse time diagrams of the switch actuations, FIG. 4 the associated resonance transmission for connections in local traffic, ie the resonance circuit and "curves of the voltage profile on the capacitors, FIG. 5 analogous to FIG. 4 for connections in long-distance traffic and FIG. 6 up to 8 and 9 to 11 analogous to Figs. 3 to 5 for changed reactances in the resonance circles ^.:

According to FIG. 1, the time division multiplex switching system is divided into two groups, the subscriber group with the two-wire time division multiplex rail MS _T and the trunk group with the four-wire time division multiplex rail MS _L. All subscribers T 1 to Tm are connected to the subscriber group and the trunk lines or trunk lines Ll to Ln are connected to the trunk line group. In the case of a private branch exchange, the subscriber sets are usually located in the vicinity of the switching system, so that no line attenuation worth mentioning occurs, and the exchange lines lead to the nearest local exchange. Such a switching system can also be used advantageously as a local office, in which case the subscribers z. B. are connected by cable and can reach one or more other central units via the trunk lines.

The two- wire time division multiplex rail MS ₇ - and the four-wire time division multiplex rail MS _L are coupled to one another by two pulse amplifiers K1 and V 2, each amplifier serving one of the two transmission devices. Amplifier V 1 is provided for the direction of transmission subscriber lines-trunk lines and amplifier V2 for the direction of transmission trunk lines-subscriber lines. To separate the two transmission directions, the two amplifiers are connected to the two-wire multiplex bus MS _T via a _{timing fork formed from two alternately closable switches SF 1} and SF _2. Such similar time forks are e.g. B. in DT-AS 12 97164 described. The switches SK ₁ and SV ₂ successively connect one or the other amplifier to the time division multiplex rails for the transmission of one pulse each and serve all time-graded connections together. The further electronic switch S _VL can easily be

12844

directed to be executed; since the Ehergiefluss only takes place in the direction of the arrow sign - », corresponding to the direction of action of the 'associated Pülssteiger kers. : ■. - ^: ■■ '' ■ ■ ' ''■■■'■;: ■: ■: v: ': itü .. ■■ .-. ■ :: ■.: ■'. ■ '■ :: ■. . ·. ,

Of the control device required to operate the electronic switch, only the circulating memories with the address decoders are shown for the sake of simplicity. The structure according to the invention of a time-division multiplex switching system allows, in a particularly advantageous manner, three such: equipment to be used / two circulating memories SP _A and SPg with their ^: address decoders D _A and ^; D _B are in connection with the subscriber-side two-wire time division multiplex switch; and another circulating memory / decoder SP ^ Di is on the ^: line-side four-wire time division multiplex rail ^; connected. With this arrangement, calling and called subscribers can be distinguished in a known manner and inquiry connections and call transfers can be implemented more easily, ie with the help of the Pdlphase of the first connection: '- ^ -: v-. ■; ·.:, ·

The example shown shows that a connection of the local traffic runs through two subscriber circuits, each comprising a transformer t / j, a low-pass filter T _P and a coil Lf as well as the associated electronic subscriber switches S ₇₁ and S ₇ - ^ and the common '■ two-wire time division multiplex rail MS ₁ -. This rail enables connections between any participants, according to the switches that close at the same time. During the switching, the two coils L _n and L ₇ - ^ with the terminating capacitors of the low-pass filters Cf ₁ and C _{Tm form} a series resonant circuit, the oscillation period of which is usually twice as long as the duration of the switch closure. The charges on the capacitors are therefore transferred from one subscriber circuit to the other in the form of half a sine wave. The associated current impulse brings the speech energy or the energy of other information; despite its short duration of e.g. 1 \ js and a pause length of 99 | js, to the opposite side. From the capacitors the current flows continuously, and through the low-pass filter from the pulse repetition frequency of z. B. 10 kHz, as well as the upper sampling products released to the subscriber set. Further information on resonance transmission is given in connection with the description of the connections in long-distance traffic.

The course of the energy level for a connection in local transport is indicated by the dash-dot line in Fig. 2 shown. The main part of the total attenuation for example 0.7 neper is caused by the transformers and low-pass filters, and only one a small remainder is due to the electronic switches.

A connection from a subscriber line to an exchange line branches at the transition from the subscriber group to the line group for each transmission direction via a pulse amplifier V 1 and VI. For the exchange of messages between a subscriber line T1 and an exchange line L 1, the corresponding subscriber _{switch S 7} -I closes periodically, and during each part of its closing period, the two time fork switches S _n and Sy ₂ alternately establish a connection, with the respective transmission direction being through the connected amplifier is intended. The pulsed Energiciranspori both between subscriber line and amplifier, as well as between amplifier and trunk line can take place according to the resonance transmission principle. The speech streams are then merged on the line side in a hybrid circuit Gl, Gn or: they are separated therein for the transmission directions of the amplifier and pass through a low-pass filter to filter out the higher frequencies in the same way as on the subscriber side.

The course of the energy level of a wide area connection is in Fig. 2 by the solid step line for one or by the dashed step line illustrated for the other direction of transmission. The main components of damping will be in turn by the transmitter of the subscriber circuit and the exchange line circuit, more precisely the hybrid circuit caused, with further minor losses due to the electronic switch develop. However, the total attenuation of each transmission direction is due to the gain factor of the pulse amplifier in question balanced so that the exchange line level and subscriber line level are practically the same size.

Advantageous further developments of the time division multiplex switching system described are based on the dimensioning of the capacitors, coils and pulse times for the resonance transmissions between the subscriber lines and from the subscriber lines to the amplifiers. . ν:, -. ■ A first solution is shown in Figs. 3 to 5 and provides that the transverse capacitance C ₇₁ , C _Tm and the series inductance L ₇₁ , L _Tm in the subscriber circuits for resonance transmission via the subscriber-side two-wire time division multiplex rail such an oscillation period T ₇ - are measured, which is twice the closing time T ₇ - the subscriber switches S _n , S _Tm for connections in local traffic. For the circuit according to FIG. 4 the formula applies

2 _T _ = T _T =

"f

Ii τ

Tl

Wm) "F— r ~ F -

-n

Since the coils and capacitors of all subscriber circuits have the same inductance or capacitance values, L _n = L _Tm = L ₇ - and C ₇₁ = C ₇ - ,,, = C ₇ -, and the formula is reduced to

2T ₇ - = T ₇ - = 2.τ · (/ L ₇ - ■ C ₇ -.

This first solution for the design of the coils and capacitors of the resonance transmission is further shown in FIG. 5 characterized in that the directed to the trunks pulse amplifier V a cross capacitance C _V1 is provided by the same size parallel to the high impedance input £ 1 1, as that in the Subscriber circuits C ₇ -.

From the relationship for the oscillation period T _{vl of} the resonance circuit between a subscriber line and the aforementioned pulse amplifier

T _n = 2.t

^L l'l

C _T + C _ri '

and the dimensioning condition C _n = C ₇ - results in .... ■■ ...

| ΓΤ ·

or put in words:

This oscillation period in long-distance traffic is a factor of "jr = y times smaller than the oscillation period of the resonance circuit of two subscriber circuits connected in local traffic. In line with this oscillation period T _VI , in long-distance connections the closing time τ _ν \ of the timing switch S _{vl for} the direction to the exchange lines

7r == times the closing time of the subscriber counters. About 70% of the pulse phase time is available for the resonance transmission in the direction of the trunk lines. Optimal resonance transmission is dispensed with in the opposite or incoming direction going to the subscriber lines. The remainder of the pulse phase, or f · rpy J times the closing time of the subscriber switch, is available as the closing time for the associated time fork switch S _V2.

As advantages of this solution. can do with connections Ideal transmission times that can be used in local traffic and in outbound long-distance traffic of half an oscillation period of each of the resonance circles involved. ,

In FIG. 3, the pulse diagrams of the switches of a connection in long-distance traffic are drawn for actuation in a specific pulse phase. The upper diagram applies to a subscriber switch S _T , the middle one for the time fork switch _{S vl of} the direction to the. Trunks and the lower diagram for the second time fork switch S _{V2 of} the direction to the subscriber lines. From the illustration it can be seen that during the closing period T ₇ - the subscriber switch first For the

times the duration of the timing switch S _{n of} the

going and then for the

Capacitors C ₁ -. and JC ^ j, but now only one coil L ₇ -, and, as was shown above, has one

by the factor ji = fnäl smaller oscillation period than the resonance circuit according to FIG. 4. Accordingly, the; Closing time 7y. _{r of} the! time switch Syi by the factor; jr ^ ymäi be shorter than'die

multiple part

the time fork switch S _{V2 of} the incoming transmission direction are closed.

The F i g. 4 shows the circuit of the resonance circuit of a connection in local traffic and the voltage curve on the capacitors C _n and C ₇ - ,,, during a transmission pulse.

Since both capacitors have the same capacitance values and the oscillation period of the resonance circuit T ₇ - corresponds to twice the amount of the closing _{duration r r of} the subscriber switch S _T , the voltage values of the capacitors are transferred to the values on the opposite side in an oscillation half-cycle. As an example, it is assumed that at the beginning of the transmission, at the moment when both subscriber switches are closing, the voltage value 1 is _{present on the capacitor C 71} and the voltage value 0 is present on the capacitor C _Tm. At the end of the closing period r _T , the voltage values have then interchanged, the voltage on the capacitor C _n has now dropped to 0, and the voltage 1 has built up on the capacitor C _Tm. Of course, any other voltage values can be present at the beginning.

5 illustrates the relationships of a connection in long-distance traffic, ie it shows the interconnection of the resonance circuit during the simultaneous closure of the subscriber switch S _T and the timing switch _{S vl in} the direction to the amplifier K ₁ or to the exchange lines. The resonance circuit again consists of two equal closing times of the, subscriber switch; The voltage curve at the capacitors C ₇ - and C _v { has the shape of a half sine wave, analogous to that at the capacitors G _n and C _Tm. · ■■: ■ ^; : ·: · ■! ·. · .;

As a second ... solution to the resonance transmission problem for the subscriber-side two-wire time ^ multiplex rail. it is provided that on the one hand the transverse capacitance C ₇₁ , C _TM and the series inductance L ₇₁ j L _Tm in the subscriber circuits for one oscillation period. are dimensioned that; at. Connections in local traffic is twice the associated closing time T _T jv of the subscriber switches S ₇₁ , S _Tm , that on the other hand between the two time fork switches S _V1 , Sy ₂ and their pulse amplifiers F ₁ , V ₂ each have a transverse capacitance C _vi , C _V2 ypn. the same size as used in the subscriber circuits and that accordingly for connections in long-distance traffic the closing time of the subscriber switch is twice that of the two time fork switches

each the "j7 = y times the closing time of the subscriber counter in local traffic amount to ... -,

With the transverse capacitance in each of the pulse amplifiers, it is no longer just for the outgoing direction, but for both transmission directions of the long-distance connections the period of oscillation by the factor Trymal smaller than the oscillation period of the Resonance circuit of two subscriber circuits connected in local traffic. The same ratio factor

of Y = j exists between the relevant oscillation half waves and therefore also between the duration of the closure of one of the two time fork switches and the subscriber switch operated for local traffic. In long-distance traffic, on the other hand, the latter must maintain the connection while the two time fork switches are closed, ie a 2 · i7 = v = far longer than in local traffic

Have closed periods. There are thus two different types of tax for the subscriber counter. The F i g. 6 shows the pulse time diagram of the switches involved, namely the subscriber switch S ₇ - with the closing period r _TN for local traffic, the l ^ times longer closing period t _tw for long-distance traffic, then the diagrams of the two time fork switches S _Vi and S ₁ Z ₂ , which the time division multiplex rail alternately during half the closing period 2 T ₇ -H- of the subscriber switch in long-distance traffic, ie during j7 = y · τ _ΓΛ · to the amplifiers

connect through.

In Fig. 7, as in FIG. 4 for the first solution, the circuit and the voltage curve on the Capacitors of the resonance circuit in local transport drawn and in F i g. 8 the same for long-distance traffic. While for local traffic and the direction of transmission to the trunk lines or the Vcr-

509 547/126

stronger K ₁ in long-distance traffic the capacitor voltages are assumed to be 1 and 0 at the time the switch is closed, the voltage across the capacitor C _{V2 was} chosen to be lower. In all cases, the voltage values are transmitted in the form of a sine half-wave for the amount of the opposite side, because the duration of the closure of the connections is half the oscillation period of the effective resonance circuit and the cross capacitances of the transmission endpoints are the same.

The advantage of the second solution lies in the ideal ratios for both directions of transmission Long-distance and local traffic connections.

The third solution for dimensioning the resonance transmission via the subscriber-side two-wire time division multiplex rail is shown in FIG. 9-11. It provides that the transverse capacitance C _n , C ₇ - ,,, and the series inductance L _n , L _Tm in the subscriber circuits for an oscillation period T ₇ - are dimensioned, which is two thirds of the closing time r _{r of} the subscriber switch S for connections in local traffic _n , S ₇ ; ,,, is. Further, between the two time fork switches S _vu S _V2 and their pulse amplifiers V _1, V _{2 n} each have a series inductance L _V1, Ly ₂ and a cross capacitance C; Cy ₂ of the same size as. in the subscriber circuits, and accordingly, in the case of long-distance connections, the closing time τ _{ν of} the time fork switches can each amount to a third of the closing time of the subscriber switches.

The period of oscillation T ₇ - is three times smaller than in the first solution and is calculated using the formula

_/ 2

T ₇ - = 2.τ y L ₇ - ■ C ₇ - ^ - ^ T ₇ -.

this expression also applies to the resonance circuit between a subscriber circuit and one of the pulse amplifiers, as shown in FIG. 11 is shown. The period of oscillation Ty for the conditions in long-distance traffic is accordingly

7V = T ₇ . = 2.T./L _7. -C ₇ . = 2τ ,,

and the duration of the closing of the time fork switches

_ 1 _ ■

For connections in local traffic, the energy is transferred from the capacitor C _n to the capacitor C _Tm according to FIG. 10 in the form of three half sine waves or I ¹ Z ₂ periods. Due to the inevitable losses, the voltage at the end of the closing time T ₇ - will be somewhat smaller, as the dashed curves show. This attenuation must be taken into account when dimensioning the subscriber transformer.

The advantage of this third solution lies in the ideal conditions for long-distance traffic connections, similar to the second solution, and in the constant control of the subscriber switch for local and long-distance traffic.

For this purpose 2 sheets of drawings

Claims (4)

Patent claims: 1. Time-division switching system, especially time-division multiplex - telephone extensions - switching system, for subscriber lines that are to be connected in local traffic with each other and in long-distance traffic with trunk lines and with amplifiers, characterized in that each subscriber line (T 1 ... Tm) two-wire via a lossy Subscriber circuit and a downstream resonance transmission device (CT, LT, ST) can be connected to a first time division multiplex rail (MST) during the closure period (τ _τ ) of the associated subscriber switch (ST1), which first time division multiplex bus (MST) for long-distance traffic during the closure period (t _t ) of the assigned subscriber switch (STl) one after the other first via a first pulse amplifier (F1) and a first switch (SFl) in series to the transmission branch and then via a second pulse amplifier (F 2) and a second switch (SV 2 in series) ) to the receiving branch one with line switches for the connection of exchange lines (L 1 ... Ln) provided second time division multiplex rail (MSL) can be switched on. 2. System according to claim 1, characterized in that for resonance transmission over the subscriber-side two-wire time division multiplex rail (MS _T ) on the one hand the transverse capacitance (C ₁₁ , C ₇ -J and the series inductance (L _n , L _Tm ) in the subscriber circuits for an oscillation period (T ₁ ) , which for connections in local traffic is twice the closing time (τ _Τ ) of the subscriber switches (S _n , S _Tm ), and that on the other hand, parallel to the high-resistance input (E ₁ ) of the pulse amplifier (F ₁ ) a transverse capacitance (C _V1 ) of the same size is used as that in the subscriber circuits, and that accordingly for connections in long-distance traffic the closing time (τ _η ) of the timing switch of the direction the exchange lines (S _n ): 7 = y times the closing time of the subscriber switch and the closing time (Ty ₂ ) of the other time switch (Sy ₂ ) Π - w == J times the duration of the closing time of the subscriber counters. 3. System according to claim 1, characterized in that for resonance transmission via the subscriber-side two-wire time division multiplex rail (MS _T ) on the one hand the transverse capacitance (C _n , C _Tm ) and the series inductance (L _n , L _Tm ) in the subscriber circuits for an oscillation period ( T ₁ -), which for connections in local traffic is twice the associated closing time (τ _ΤΝ ) of the subscriber _{switches (S n} , S _Tm ) , that on the other hand between the two time fork switches (S _n , Sy ₂ ) and their pulse amplifiers (F ₁ , F ₂ ) each has a transverse capacitance (C _n , Cy ₂ ) of the same size as used in the subscriber circuits and that accordingly, for connections in wide area traffic, the closing time of the subscriber switch is twice as long and that of the two time fork switches each Tr === times the The closing time of the subscriber counter in local transport (t _tn ) . 4. System according to claim 1, characterized in that for the resonance transmission via the subscriber-side two-wire time division multiplex rail on the one hand the transverse capacitance (C _n , C _Tm ) and the series inductance (L _n , L _Tm ) in the subscriber circuits for an oscillation period (T ₇ -) are measured, which is two thirds of the closing time (r _T ) of the subscriber _{switch (S n} , S ₇ - ,,,) for connections in local traffic, and that on the other hand between the two time fork switches (S _n , Sy ₂ ) and their pulse amplifiers (F ₁ , F ₂ ) a series inductance (L _n , L _V2 ) and a transverse capacitance (C _n , Cy ₂ ) of the same size as in the subscriber _{circuits (L 7} -, C ₇ -) are used and that accordingly for connections in long-distance traffic the closing time (τ _ν ) of the time fork switches is one third of the closing time of the subscriber counters.