DE1067076B - Electronic switching system - Google Patents

Description

GERMAN

In electronic switching systems that operate on the time division multiplex principle, i. i.e., at those certain pulse phases are used for the optionally producible message channels, one summarizes Usually pulses of the same purpose are shared on multiplex lines. Pulse The same purpose are, for example, those pulses which the subscriber stations represent outgoing and incoming connections. These pulses are in the switch combined on one multiplex line each, so that one outgoing and one incoming Multiplex line are provided. These multiplex lines are then used to establish the connection required switching devices connected in multiple circuit, since over each multiplex line a plurality of connections can be handled because of their particular phase assignment.

Certain criteria are now required to establish the connection, e.g. B. a call criterion and a busy criterion. Pulses are also used for this.

In the previously known time division multiplex systems, whose basic features are, for example, in the Swiss Patent specification 276 281 are described, one proceeds to create these criteria as follows: An The outgoing multiplex line is connected to two amplitude filters, -which of the outgoing ones Multiplex line appearing pulses only let through certain amplitude parts. The one amplitude sieve transmits only the amplitude-modulated pulse component, the other amplitude filter transmits the unmodulated one Momentum component. The modulated and the unmodulated pulse component each become their own Multiplex line fed. These two multiplex lines then serve to establish the connection.

On the multiplex line transmitting the unmodulated pulse component, two different Criteria formed, namely a call criterion and a busy criterion, namely by Creation of two pulse amplitudes, each representing one of the two criteria. This is done on the following way: A pulse fed to this multiplex line initially appears on it with his full amplitude, which is the call criterion. This pulse is then sent by one of the in the switching system contained pulse call finder recorded by the call finder on this pulse synchronized. For this purpose, the call seekers are transferred to the unmodulated pulse component load-bearing multiplex line connected. After synchronizing on the multiplex line, the Busy criteria appear. This is produced by the input resistance of the relevant Electronic switching system

Applicant:

Siemens Sd Halske Aktiengesellschaft,

Berlin and Munich,
Munich 2, Wittelsbacherplatz 2

Dr.-Ing. Karlheinz Goßlau, Munich,
has been named as the inventor

Call viewfinder reduced in the relevant pulse phase will. This increases the amplitude of the pulse found by the caller on the multiplex line lowered. This lowered amplitude represents the occupancy criterion.

A known circuit for realizing this principle works as follows: The inputs of the Call seekers are represented by the grid of tubes, usually below the grid current area be controlled. The incoming call seeker thus causes practically no burden the connected multiplex line. After synchronization, however, the operating point becomes of the input tube so far that the tube is controlled in the grid current area. So takes the input resistance shows a value in the order of magnitude of a few kilo ohms. In contrast, of course, the internal resistance must the source supplying the unmodulated pulse component, namely the relevant amplitude filter, be selected accordingly so that the grid current use leads to a load that reduces the amplitude causes.

This method initially has the disadvantage that the resistance of the grid-cathode path the flow of goods from tube to tube is subject to considerable fluctuations, so

909 638/79

that a defined amplitude reduction on the Multiplex line is very difficult. This defined decrease in amplitude is important because it yes represents a separate criterion to which certain switching devices in the switching system respond have to. Furthermore, the input resistance, which is in the order of "a few kilo-ohms", has one synchronized call seeker with the result that the 'characteristic impedance of the multiplex line at least

further multiplex line the respective subscriber pulses from the subscriber circuit «! direct entrances the pulse call finder forwards.

This measure, according to which the respective subscriber pulses are fed from the subscriber circuits directly to inputs of the pulse call seeker via a further multiplex line to hold the pulse call seeker synchronized on-5, makes it possible to have a free pulse call seeker only at the beginning of an order of magnitude above this when through In the first dial sent out by a subscriber station, the onset of grid current actually stimulates a designation and not already when the load changes and thus a decrease in amplitude of the subscriber in question, as is supposed to occur with the change. ■■■■ ■ ■ '■ the above-mentioned, already proposed

.. This latter requirement “is with. Mediation. Mediating system is the case. On this particular one

systems with a large number of subscribers and thus no longer realizable 15 advantage of the switching system according to the invention speaking low pulse width, which is explained in the following example: In
-a usual pulse frequency of a participant's pulse
of about 10'kHz and 100 participants is obtained for
the collective pulse (this is the summary of all 20 system, participant pulses phase-shifted with respect to each other) works. Of the

will be discussed in more detail below.
. The circuit arrangement according to the invention is explained in more detail with reference to the drawing. The figure shows a complete electronic switch which is based on the time division multiplex system for the sake of clarity

stood from 10 kilo ohms and over, as he would with an input resistance of the pulse call seekers of some Kiloohm would have to be chosen, no longer feasible.

In another known multiplex system, the various criteria become as follows shown: When the handset is picked up at a subscriber station, the associated subscriber appears

a repetition frequency of 1 MHz. In order to transmit a circuit group which is not more closely related to this interPuls of 1 MHz with the necessary edge steepness, the transmission means must at least be composed. The system shows that the two strongly drawn out have a cut-off frequency of 10 MHz. With a 25 drawn multiplex lines Ml, M 2 on, at cutoff frequency of. 10 ¹ MHz, however, is a wave resistance to which the subscriber stations Tl, T 2 are connected via the fork circuits G1, G 2 . As an outgoing multiplex line, the line Ml transmits the messages in the direction from the subscriber station 30 to the switching device, the line M 2 as an incoming multiplex line in the direction from the switching device to the subscriber station. The number of possible participant positions is generally based on the number of. available pulse pulse on an outgoing multiplex line, to which 35 phases. Usually, a normally open gate circuit is connected in the fork circuits , G2, G2 except for the split or merging. Via this gate circuit, a pulse recording of the traffic directions and the modulation of the call seeker is triggered, which then emits a pulse in or the demodulation of the subscriber pulses P1 and the phase position of the subscriber pulse. At the same time P2, which is fed to the gate circuit 40 hybrid circuit via its own feed line of the relevant timely from the pulse call searcher, is blocked with the message. The pulse call finder contains its own pulse and dialing symbols. In the incoming direction there are springs that ensure this; that the pulse call seeker the hybrid circuits Gl and G 2 to the incoming after the trigger continues to run independently. This makes multiplex line M 2 connected. In outgoing then at the end of the conversation a special final direction, the modulated subscriber pulses of the characters are required, with which the pulse call 45 outgoing multiplex line M1 is fed, seeker is put out of operation. If a participant picks up, his / her part appears

. A switching system has already been proposed receiving pulse on the outgoing multiplex line Ml. been that the disadvantages of the known systems, the dialing characters of the subscriber, in particular so

namely different amplitude values, a special one the number switch pulses, modulate the

■ Closing signal and pulse call seeker with his own pulse- 50 hitting participant pulse in such a way that it is in time .Sources, thereby avoiding the need to keep the dialing characters strongly increased in amplitude

will. This increase is sufficient to exceed the threshold value of the amplitude filter A , which is connected to the outgoing multiplex line Ml. 55 The pulses transmitted by the amplitude filter ^, which thus occur with the first dialing character, reach the stimulus line M 4 via the gate circuit To , which is open in the idle state, to which the pulse call searchers AS1, AS2 of the system are connected, which are used to establish the connection are. The number of pulse call seekers depends on which one (stimulus line) depends on the number of connections that are to be switched to the system simultaneously from the outgoing multiplex line via a gate circuit. A pulse that appears to be fed and to trigger and on synchronous incentive line M 4 causes sieren voii pulse call seekers to the respective part - a free pulse call seeker is synchronized on. - receiver pulse phase is used and another (blocking line) 65 After synchronization, the pulse call seeker in question delivers a blocking pulse after synchronizing the pulse call seeker, which appears on the gate circuit for everyone on this multiplex line blocking line M 5, which is sent to everyone's outputs

The circuit arrangement. Pulse call seeker is connected. According to the invention, the barrier is characterized in that the gate circuit To is now controlled for line M 5. Holding the synchronized pulse call seeker a 70 This is designed so that it is in the idle state of

synchronized pulse call seekers another multiplex line feeds the respective subscriber pulses from the • outgoing multiplex line directly to inputs of the pulse call seeker.
; The invention, which also avoids the disadvantages of the known systems, takes a different approach to creating the individual criteria.

Other multiplexing systems are also used.

the amplitude filter A is switched through to the stimulus line M 4, but blocks when a blocking pulse is supplied from the blocking line M 5 for the pulse phase. As a result, when a blocking pulse occurs on the blocking line M 5, the associated stimulus pulses must disappear on the stimulus line MA . This ensures that only a single pulse call seeker can synchronize to a pulse. So that the synchronized pulse call seeker is now held on the found subscriber pulse for the duration of the connection, each pulse call seeker is still connected to the hold line M 3. The subscriber pulses are fed to this in the following way: The subscriber pulses are not only on the hybrid circuits Gl and G2 but also on the gates ToI and To 2, which are blocked in the idle state. These gate circuits are opened by a potential derived in any way from the hybrid circuits when the subscriber in question lifts off. The relevant gate circuit To 1 or To2 now transmits the associated subscriber pulse to the hold line M 3 until the subscriber hangs up again. The subscriber pulse of the calling subscriber is thus present on the hold line M 3 for the duration of the connection, so that the synchronized pulse call seeker is held via the hold line M 3. However, an incentive to synchronize cannot be exercised from the holding line M 3.

The holding line M 3 can also be fed directly from the outgoing multiplex line M 1 and thus the outgoing subscriber pulses can be used to hold a synchronized pulse call seeker. Then the gates ToI and To 2 cease to exist, but there is a certain uncertainty when holding the pulse call seeker, since the subscriber pulses transmitted by the outgoing multiplex line Ml are modulated. If this modulation reaches approximately 100%, the pulse amplitude becomes very small at times, as a result of which holding the pulse call seeker can be unsafe under certain circumstances.

Call to the pulse finder ASl and AS2 each one of the intermediary Vl and V 2 is connected, via which the communication link is established. The intermediaries thus take on the task of converting the message from the subscriber pulse of the calling subscriber to that of the called subscriber and vice versa. For this purpose, the intermediaries receive from the associated call seekers the subscriber pulse of the calling subscriber to whom the relevant call seeker has synchronized, and thus enable the recording of the dialing signals transmitted as modulation, which the intermediaries receive from the outgoing multiplex line M1. The outputs of the switch are on the incoming multiplex line M 2, which leads to the subscriber stations T1 and T 2 via the hybrid circuits G1 and G 2.

So that no further call seeker can be stimulated by lifting the called subscriber, whose subscriber pulse appears on the outgoing multiplex line M1 , the subscriber pulse of the called subscriber is now also given on the blocking line M 5. This is done by the occupied agent. Both mediators Vl and V2 are connected to the inhibit line M 5, so that therefore the gate To is also locked to the subscriber pulse of the called subscriber and, consequently, by reporting of the called subscriber is no incentive to another still free call viewfinder can be exerted. :

From the explanations above it can be seen that a total of three multi-

; Plexleitungen 5, namely the hold line M 3, the incentive M. line 4 and the inhibit line M 5, must be provided. The appearance of a pulse on one of these multiplex lines represents a specific criterion, regardless of the amplitude of the

ίο Pulses. The structure of these multiplex lines brings no difficulties with it, since the multiplex lines even with large numbers of participants and accordingly high cut-off frequency can be fed with any low resistance and consequently also you Characteristic impedance can be selected correspondingly low.

The following advantage of the circuit arrangement according to the invention should also be noted: As already explained, the stimulus line M 4 does not receive its impulses until the beginning of the first dialing signal. As a result, a free pulse call searcher AS1 or AS 2 also receives its incentive only with the beginning of the first dialing signal sent by the subscriber station T1 or T 2 and not already when the subscriber in question lifts off. In this way, the occupancy duration of the common equipment, namely, the pulse finder call ASl and AS2 and the intermediary Vl and V 2, limited to the minimum necessary. In particular, this avoids unnecessary occupation of these shared facilities by simply picking up and not dialing a subscriber. The evaluation of the first dialing character immediately following the synchronization of a free pulse call seeker does not present any difficulties, since the type of system described here generally uses pulse frequencies of .10 kHz, which are sufficiently large compared to the usual repetition frequency of the pulses generated with number switches of 10 Hz . This ensures that the first number switch pulse is also reliably evaluated. - To feed the entire switching system, the centrally arranged pulse generator PG is also indicated in the drawing, which supplies the system with the necessary pulses.

Claims (2)

Patent claims 1. Circuit arrangement for switching systems that work according to the time division multiplex principle and in which pulses of the same type are combined on multiplex lines, of which one line is connected as an outgoing multiplex line in the outgoing direction and another line as an incoming multiplex line in the incoming direction to the subscriber stations and still further multiplex lines for the connection establishment are provided, of which one (stimulus line) is fed from the outgoing multiplex line via a gate circuit and is used to initiate and synchronize pulse call seekers to the respective subscriber pulse phase and another (blocking line) after synchronizing the pulse call seekers the gate circuit for everyone on this multiplex line appearing pulses locks, characterized in that a further multiplex line (M 3), the respective pulse for holding the aufsynchronisierten call finder (ASL, AS 2) "Passes subscriber pulses from the subscriber circuits directly to the inputs of the pulse call finder. 2. Circuit arrangement according to claim 1, characterized in that the gate circuit (To) is preceded by an amplitude filter (A) which transmits only those subscriber pulses that are modulated by dialing characters. Documents considered: German Patent No. 920 492;
Swiss Patent No. 276 281; British Patent Nos. 644861, 722179. Older patents considered: German Patent No. 1007 379. 1 sheet of drawings