Circuit for setting up conference connections in a digital time multiplexed telecommunication exchange.

The invention relates to a circuit arrangement for establishing conference connections in a digital time-division multiplex telecommunication exchange with a conference unit which is located in a the output of the cyclically writable and optionally selectable speech memory of the coupling arrangement, preferably group switching arrangement of the switching center, connected with the input of feedback loop, further to the the input side and output side connected to the voice mail Super highways for parallel transmissions of PCM words on the number of time slots addition in which information transmissions vo and the exchange takes place (transmission time fan), also formed, immediately successive time slots (conference time slots), the one of the number of simultaneously possible conferences same number each as many time slots as a maximum Konferenzteilnehmner per conference are possible, make extensive number of groups, and in addition to in the course of an exchange of two compounds necessary voice mail or holding memory cells provided with the voice mailbox and its associated latch, said conference time cells associated conference memory cells, during a conference call receives the conference unit by choice free reading from the speech store converted into conference time cells individual signals of the conferees and forms from these conference subscriber-Endsummensignale that in corresponding conference time cells outputs respectively do not include the own contribution of the participant and to the input side Super highway, from where departing from them during cyclical writing to the associated additional voice memory cells and, after reading these random Endsummensignale assigned in the conference transmission time slots are further transmitted to the output side Super highway. The stated there conference unit may be provided to form the conference subscriber-sum signals with signal processors. In practice, it is generally sufficient if circuits are designed to Herstellugn conference calls so that they can use a relatively small number of conferees per conference, for example, 4 conference participants. In such cases, the use of signal processors in the conference unit is too expensive solution.

The object of the invention is a circuit arrangement for producing specify conference calls, which is a expenses and cost-effective solution under the given conditions and in terms of a small number of conferees per conference.

This object is achieved by the features specified in the characterizing part of claim 1 means.

The invention by way of example with reference will be explained in greater detail to a drawing.

In the drawings:<ul><li>1 shows the exemplary structure of a digital time-division multiplex switching center.</li><li>Figure 2 that part of such a time-division multiplex switching center, which is associated with the inventive circuit.</li><li>Figure 3 shows an embodiment of the inventive design conference unit.</li></ul>

The terminal groups LTG1 to LTGn form the interface between the analog or digital environment the exchange and the switching network. On it are accordingly with users connecting subscriber lines and / or connecting with other exchanges interconnectors PCMe0 connected to PCMe11.

The terminal groups as essential components, as shown in the terminal group LTG1 in detail, terminal units LTU 1 to LTUx, which in turn contain the subscriber sets or wiring harnesses, not shown here, further comprising a group switch GS, an interface unit LIU that the interface between the terminal group and the group switch represents a signal unit SU, and a group processor GP that controls the aforementioned units and furthermore processed on the subscriber or connecting lines received dialing information and in connection with the establishment and release of connections to the coordinate processor CP is in control characters exchange. In addition, the group processor performs GP routine checks and assumes monitoring tasks.

2 shows a detail here of interest of the terminal group LTG is the arrangement according to Figure 1 dargestelt more detailed extent.

It is provided that the connection of 12 PCM lines, on each of 32 time slots are formed. The branches for the incoming transmission direction PCMe0 to PCMe11 this PCM lines are connected to a serial-parallel converter SPC, which also acts as a multiplexer, through which the individual bits of the incoming to the PCM lines PCM Wote by a serial-parallel conversion under the condition of 8 bits per PCM word on the 8 wires of the receiving branch SMLe a multi-core super highway are distributed and which are interleaved by multiplexing on this highway in time such that initially sequentially on the PCM lines PCMe0 to PCMe11 in timeslot 0 transmitted PCM words occur successively, then successively transmitted in time slot 1, etc., and finally the data transmitted in timeslot 32 PCM words.

However, the sequence control of said multiplexer operates with such a high readout clock that besides the 12 x 32 = 384 time slots for the PCM words of the 12 PCM lines, which are referred to as transmission time slots, additional time slots are formed, referred to herein as conference time cells. According to an assumed maximum number of 4 conferees per conference and 32 simultaneously possible conferences, these are 4 x 32 additional time slots, which form 32 groups of 4 sequentially occurring time slots.

The mentioned receiving branch SMLe the super highway leads to a voice memory SM which zuzsammen forms with the corresponding control the group coupler GS according to FIG. 1

The voice memory SM has in accordance with the formed on the super multiplex line 384 transmission time slots to 384 memory cells for each 1 PCM word. In addition, according to the mentioned additional conference time cells, it has more memory cells 128 for each one PCM word, the form 32 are respectively a conference associated with groups of four memory cells for 4 beteiligbare a conference conference participants. Writing in the voice memory SM of the incoming branch SMLe the super highway from cyclically, the reading on the outgoing branch SMLa the super multiplex line contrast randomly. In this outgoing branch SMLa the super multiplex line corresponding Verhätnisse prevail as on the incoming branch SMLe.

Figure 2 also shows a conference unit CONU lying in a feedback loop through which is connected with a corresponding switching position of switches S1 and S2, the output of the speech memory with its input. Receipt of the conference unit is CONU means LIN for converting non-linear code representation arranged in linear code representation, the output side of the conference unit means COM which is the opposite conversion of linear code representation in nonlinear code representation.

The illustrated arrangement is under the control of a controller GSC, the central part of a holding memory CM which provides the drive addresses for the optional reading of the speech memory SM. This voice mail therefore contains an equal number of memory cells as the voice memory SM, of which are those that receive the drive addresses for contiguous with the conference memory cells in the voice memory grouped in a corresponding assignment, namely 32 four groups according to corresponding to 32 possible simultaneous conferences, each with four memory cells four conferees per conference included. Other components of the control GSC dind a processor interface PS to a microprocessor uP, a counter ZZ, the select addresses for the 512 storage cells of the speech memory SM during cyclical writing supplies, also an input timing counter EZ, which counts the transmission time slots on the Super highway for the incoming transmission direction SMLe and after whose lapse respectively the switch S2 is operated. Finally, an output timing counter AZ is provided, the transmission time slots is one in a similar manner to the super multiplex line for the outgoing transmission direction SMLa and provides a control signal for the switch S1.

Figure 3 shows how the conference unit (CONU) constructed according to the invention, with the proviso that a maximum of four conference participants can join a conference.

The conference unit according to Figure 3 thus has four temporary registers A, B, C and D, in which the coming of the conference individual signals, which have been implemented by means of the voice mail to the corresponding conference time slots, are cached.

The conference unit according to the invention further comprises an adding network which consists of adders AK1 to AK6, which are arranged in two stages of which the first stage of the adder AK1 and AK2 and the second stage comprises the adder AK3 to AK6. The adder AK1 is connected to the outputs of intermediate registers A and B, and accordingly forms from the individual signals of the subscriber A and B, the partial sum A + B of adder AK2 is connected to the intermediate register C and D, and accordingly forms the partial sum C + D from the individual signals of the conferees C and D.

The adder AK3 Addiernetzwerkes of a single signal, namely the content of the register A and the output from the adder AK2 partial sum signal C + D is also supplied. It thus provides a Endsummensignal SB = A + C + D, which is temporarily stored in an output-side intermediate register SB. Similarly, the adder AK4 obtained from the intermediate register B. from conferee B supplied single signal and the partial sum signal C + D is formed by means of the adder AK2, from which he = B + C + D is the final sum SA, which is temporarily stored in the output-side intermediate register SA , The contents of the intermediate register C is supplied with the output by the adder AK1 partial sum signal A + B adder AK 5 to form the Endsummensignals SD = A + B + C, which is temporarily stored in the output-side intermediate register SD. Finally, the adder AK6 serves to form from the contents of the intermediate register D and the output by the adder AK1 partial sum signal A + B the Endsummensignal SC = A + B + D, which is temporarily stored in the output-side intermediate register SC. With a larger number of conferees maximum beteiligbaren the adder network comprises a further stage of adders, which then only partial sum signals are supplied as input variables.

Under the control of a controller St, which also causes the timely entry into the aforementioned input-side intermediate registers A to D, the contents of the output-side intermediate register SA is read to SD during corresponding conference time slots.

Below is first received on the processes involved in the development of a normal two-party connection. Assume that a connection between a subscriber A and a subscriber B should exist, the associated in them time slots on the incoming branches PCME the time division lines or in the corresponding transmission time slots on the Super highway for the incoming transmission direction SMLe PCM words to the voice memory SM supply in which these assigned in these time slots in the course of the cyclical writing memory cells are stored. By selectively free reading arrive originating from the subscriber A PCM words in the on the Super highway for the outgoing transmission direction SMLa subscriber B associated transmission time slots, whereas conversely arrive originating from the subscriber B PCM words in the subscriber A assigned on this highway SMLa transmission time slots. The conference unit has no function in this context.

Now, a closer look at the processes involved in the development of a conference using the inventive circuit arrangement. It is assumed that a conference between four conferees A, B, C and D is made, the individual signals in the form of corresponding PCM words in them to the incoming branches PCME and the time-division multiplex lines or on the corresponding transmission time slots on the Super highway SMLe for deliver the incoming transmission direction to the voice memory SM, in which this, as indicated above, associated by cyclical writing into the said transmission time cells memory cells are stored. For random reading of the relevant memory cells now takes place but in contrast to the situation in the above-mentioned two-way connection, a reaction in formed on the super highway SMLa immediately successive conference time slots of the conference associated with the relevant group of conference time cells. About the switch S2, which is controlled by the counter AZ during these periods assumes the switching position shown, and on the establishment of LIN, which performs linearization, they get to the conference unit CONU. There are four Endsummensignale are formed, each of which, do not contain the individual signal of that conference part Nehmes for which they are intended. This Endsummensignale reach a caching in the caching SA, SB, SC and SD and a code conversion of linear coding in nonlinear coding by means COM in corresponding successive conference time slots via the switch S2, to the input of the speech memory SM, where it during the cyclical writing associated in the mentioned conference time cells memory cells are stored. then carried through optional activation of these memory cells, a reaction to the mentioned conference participants A, B, C and D in at the super multiplex line for the outgoing transmission direction SMLa for educated transmission time slots, from where on the now switched switch S1 to the parallel-serial converter PSC and since departing from the outgoing to the question or the relevant branches PCMa0 to PCMa11 time multiplex lines.