FI80556C - Procedure for connecting conference participants - Google Patents

Description

1 80556

A method for connecting conference participants

The invention relates to a method for interconnecting conference participants in computer-controlled telephone exchange equipment with digital switching. It is known in telephone exchanges to connect conference connections, whereby the number of connected telephones is limited to a low number. These conference devices are preferably designed for telephone substation equipment and only allow the participation of a connected participant via the central line. In this case, the strict regulations of the transmission technology regulations must be observed (DE patent publication 3 144 267).

In order to set up such conferences, it is still known to store the number of participants in computer-controlled telephone equipment 15 and to control the number of connected participants by means of concatenation memory, priority memory and central conference participation memory, for example up to four conference participants simultaneously connected (DE application 3 206 830).

The object of the invention is to provide a method which also allows a so-called large conference for public local telephone exchanges, for example with up to 20 participants, each participant being connected to an arbitrary domestic or foreign telephone exchange and only the conference call participant connected to a local conference center. .

This object is solved by the invention as set out in the characterizing part of the first claim. Other preferred embodiments of the invention appear from the features of the subclaims.

The invention will now be described in more detail with reference to the accompanying drawing, which comprises three figures. In this drawing 2 80556

Figure 1 shows a block diagram of a digital computer controlled local telephone exchange with a conference connection,

Figure 2 shows a block diagram of a cascade arrangement of conference circuits 5 and

Figure 3 shows a block diagram of the level evaluation control.

The digital local telephone exchange (Figure 1) is divided into three areas: the connection groups LTG, the switching network 10 SN and the control processor CP.

The connection groups LTG form the connection analogously

or between the digitally controlled participant locations and the switching network SN. Each interface group LTG uses a group switch or speech multiplexer-15 SPMX, a signal unit SU and an LTU from the interface unit via its own group processor GP.

for wiring connections and for the LTU connection with the switching network SN.

The group processor GP serves to control the processing of the participant groups, the group switch or the speech multiplexer SPMX, the interfaces 20 LIU and the selection information and to perform tests. Such an interface group LTG is an independent unit to which typically 256 participants or 120 digital interface lines or a combination thereof can be connected.

For conference connections, such a digital telephone exchange has either its own conference interface group LTGK or the conference modules KM are placed under the existing interface groups LTG, so that in small telephone exchanges no space is wasted for a complete interface structure group.

30 The following example starts from one of the own conference interface structure groups according to Fig. 1, but it applies equally well to the conference modules KM inserted in the LTG interface groups.

Il 3 80556

Large conference connections are controlled via conference modules KM (Figure 1), which are adapted to a special conference connection group LTGK. The LTGK conference interface group is equipped with a maximum of four conference-5 modules KM1 ... KM4. Each conference module KM

in turn, consists of four conference circuits K, with each conference circuit K being accessible through eight gates. Thus, each conference module KM can serve 32 ports.

10 The smallest unit that can meet the requirements for connecting participants as a conference interface is conference circuit K. Thus, a full number of conference circuits K are required for each conference connection.

It is not possible to reserve individual gates for conference circuit K. All conference participants who participate in a conference call will be served by a single conference device connected to the local center of the conference call participant.

Depending on the current need, 20 different number of LTGK conference connection groups have been connected to the center. Each conference interface group LTGK operates independently of each other because they represent detachable structural units and never two conference circuits K of the same or two different conference interface circuits LTGK of the same center are connected to the same conference connection. Thus, of course, several separate conference connections simultaneously within one conference connection group LTGK are possible and in the case of a small conference connection group LTGK, several conference connections within the same conference module KM. No special additional equipment is required on the side of the participants 30 to use the "large conference" (or "telephone meeting") power symbol. The connection procedures required for the connection of conference participants are solved with the help of the conference interface group LTGK. Only the 4 80556 conference call participants KATLN must have a multi-frequency selection terminal available to perform the required brochures via the terminal. The participants in the conference, the KBTLN, can use arbitrary 5 terminals, for example also operating by the impulse selection method, and be connected to an arbitrary domestic and / or foreign local exchange.

To generate and distribute the conference signal, an input is established in the conference port for each of the 10 conference participants via the switching network SN. In addition to the convening participant KATLN (conference call participant), a minimum of three and a maximum of 20 invited participants KBTLN (15 conference participants) participate in a conference call using the power symbol "large conference".

Depending on the number of participants, the conference group needs a set of conference ports. Since K has 8 ports in each conference circuit, up to 8 conference participants can be connected. When there are more than 20 8 participants, several conference districts K must be connected

using a cascade connection. The cascading is shown in Figure 2. It is performed via the internal connection of the conference interface group LTGK, in each case from one K-port of the second conference circuit to the K-port of the other conference circuit (e.g. from 25 ports K1.6 to port K4.1). The conference circuits are connected to each other in a star-like manner, whereby the center always forms the conference circuit K, which is connected to the convening participant KATLN. Chain-like interconnection of conference circuits K is also possible, but it does not offer any advantages in terms of a star-like arrangement.

For this type of conference participant interconnection field, it is provided that in one conference interface up to three channels are switched on simultaneously. The sum signal for the conference module KM is then generated via particularly fast digital signal processors 80556. If more than three participants speak at the same time, then not all speaking participants but only the three loudest speakers will be taken into account. That is, a sum signal n is generated from the speaking participant-5, in which the speech channels of the three loudest speakers are divided in the listening direction. This offers the advantage that each conference participant hears a maximum of three speakers without attenuation.

The decision as to which conference connection channels are 10 active and which are not is performed by the user program in the LTGK group processor GP of the conference interface group. For this purpose, it is necessary to determine the currently active conference connection channels, to determine and evaluate the prevailing level for each participating conference circuit K. The characteristic 15 image for a conference connection with its levels is stored in the group processor GP for each conference port. In each case, a new solution is determined which conference ports are routed active and which inactive are executed on the basis of a new level declaration. The result of this tuning 20 is given via a signal multiplexer in the form of a setting command to the participating ports of the conference circuits K.. However, each new level message does not result in a second tuning or reconnection.

The image per conference connection contains a memory location for the last 25 reported levels and has a maximum of 21 locations (1KA-TLN max. 20 KB-TLN). Because the signal processor can serve up to 8 PCM channels for dynamic reasons, up to 16 conference interfaces for each of the 8 participants are possible in a single conference interface group LTGK. As a result, this description is performed 16 times.

For hardware and software cost reasons, it is not possible for 8 ports serving a single signal processor to belong to different conference connections. Thus, 8 ports are the smallest administrative unit. Conference connections with more than 35 ports are established by cascading these units, as already described.

6 80556 A particular advantage of the tuning presented here is that the units belonging to one conference interface do not have to be included in one hardware unit, the conference module KM. This is possible due to the fact that 5 user programs have the same access to all (max. 128) ports in the conference interface group LTGK, while the hardware / software cannot exceed the conference module limit (i.e. 32 ports). Because 4-21 participants can participate in a conference connection, it is always possible to connect the KM 8 units of different conference-10 modules to a cascade when no more free ports would be available in any conference module KM than would be necessary for a new conference connection to be set up. In this case, however, there is a restriction that the units must be 15 in the same conference interface group LTGK.

If necessary, cascading has another advantage over software tuning in terms of hardware tuning in the conference module. When the software can distinguish a port to which a Conference B-participant is connected from a 20 ports to which another 8-unit is connected, this is not possible for the hardware / software. This would result in the hardware / software solution giving priority to ports involving an 8-unit, as these generally provide a higher sum signal level than the 25th conference B-participant KBTLN.

In addition to this, the software tuning has taken into account that the K K gates of the conference circuits do not often announce a new level that the group processor GP would be overloaded due to the notification leak.

30 The LTGK hardware / software of the conference interface group ensures that the individual level notifications of the individual K-gates only reach the group processor GP in connection with the mentioned changes, as a result of which short-term level fluctuations do not cause a change from active to inactive.

Il 7 80556 For this purpose, level m is integrated from the speech sample in the conference module KM. Since the memory in the group processor GP would be overloaded with additional information on the level values of the speech samples up to 128 K-port m and to further process this information from the actual tasks of the signal processors, the speech samples of one conference module are cyclically cached in RAM. The signal processor CPU reads this information and processes it. In connection with the level changes only mentioned, a signal is given from the signal processor CPU to the group processor GP of the conference circuit, which provides control from the active state to the inactive state or vice versa.

The level assessment is not performed on the basis of the absolute level, but mainly the pure speech signal is evaluated. This has the advantage that potential continuous background noise is not judged as a level and distributed in the auditory direction to all conference participants. Admittedly, such a judging threshold cannot be set arbitrarily high, because in all cases the measurement cannot be distinguished between noise and interference from the speech signal, and the participant would have to shout to be detected, there is certainly an upper and lower limit for the gate.

This adaptive evaluation threshold is set at the beginning of the conference call for each conference circuit to a K lower limit value. This output value can then only be changed in the direction of the upper limit value. The initial value of the adaptive judging threshold is reported, in which for all inactive channels, each conference circuit K is assigned a rest level of 30 and integrated with respect to the number of inactive sleep levels. If this integrated resting level is very low, then this adaptive assessment threshold remains motionless at the initial value. If this resting level is high, then the evaluation threshold rises accordingly to the maximum upper value.

β 80556

For tuning between an inactive and an active channel, a difference value between the integrated speech level and the adaptive evaluation threshold rest level is used in each case. As long as the channels are active, i.e. they are distributed in the auditory direction, this resting level determination is not performed. A special position is provided for the conference calling participant KATLN in that the adaptive threshold of the associated conference circuit K is always kept at the initial value so that the corresponding channel is always switched on in the 10 hearing directions to provide, for example, attenuator functions.

Il

Claims (11)

A method for connecting conference participants in a computer-controlled telephone exchange equipment 5 with digital switching, characterized in that a. The individual voice channels of the conference participants are connected together on a digital basis, b. The special conference circuits (K) are connected to 10 conference modules (KM) ) or specifically within its Conference Interface Group (LTGK), c. the conference circuits (K) are cascaded connected in series to carry out conferences with a relatively large number of participants s i, 15 d. generating a sum signal from the simultaneous speech levels of up to the three most active (loudest) speakers and distributing it unattenuated, e. when more than three conference participants speak at the same time, only three and g. using a difference value between the integrated absolute level of the set of participating conference circuits 25 and the evaluation threshold level between the tuning inactive and active channels (participants). A method according to claim 1, characterized in that at the beginning of each conference connection the evaluation threshold is set to a lower threshold value for each conference circuit (K). 10 80556 A method according to claim 1, characterized in that the level of speech samples of the individual conference circuit (K) is cyclically cached (RAM) via direct memory access (DMA), evaluated by a signal processor (CPU) and passed on to the conference interface group (LTGK) group processor (GP). . Method according to Claims 1 to 3, characterized in that only said change in the level of the individual conference circuits (K) is passed on to the group processor (GP). Method according to Claims 1 to 4, characterized in that the speech level of the conference participants is assessed mainly. Method according to Claims 1 to 5, characterized in that the typical image of the conference connection with its levels is stored as a reference pattern in the group processor (GP) of the connection group. A method according to claim 1, characterized in that the cascade connection 20 of the conference circuits (K) is performed within the conference module (KM) insofar as one conference circuit (K) is not sufficient for the service of all participants participating in the conference. Method according to Claims 1 to 7, characterized in that the cascaded conference circuits (K) can be arranged in different conference modules (KM). Method according to Claims 1 to 8, characterized in that the conference circuits (K) are connected to one another in a star-like manner. 9 80556 A method according to claim 9, characterized in that the conference convening participant (KATLN) is always arranged in the center of the star. Method according to Claims 1 to 10, characterized in that the conference participants can be connected to arbitrary domestic and foreign exchanges, in which case only the conference circuits (K) of the telephone exchange of the conference caller are reserved. li 11 80556