GB2044584A - Telecommunications zone apparatus - Google Patents

Abstract

A pulse code modulation concentrator zone apparatus comprises a plurality of concentrator units (K1 - Kn) Fig. 1 (not shown) each associated with a plurality of subscriber stations (TN). Each concentrator includes a control circuit (ST) and, for each subscriber, a subscriber circuit (TNS1-TNSn) identified by a call-in number. Call-in numbers fed from the exchange line (R1, R2) are, in turn, offered to all of the subscriber circuits of all of the concentrators, and a respective comparator (Vgl1-Vgln) compares the incoming call-in numbers with the call-in number of its respective subscriber circuit, and when there is agreement between the numbers it activates that subscriber circuit to receive the call. <IMAGE>

Description

SPECIFICATION Telecommunications zone apparatus This invention relates to a pulse code modulation concentrator zone apparatus for a telecommunication exchange, such as a telephone exchange, comprising a number of concentrator units each associated with a plurality of subscriber stations, each concentrator unit including a control circuit for setting up connections from and to the associated subscriber stations and a subscriber circuit for each subscriber station, each subscriber circuit being identifiable by a respective call-in number.

In known zone apparatus of this kind (cf.

NTG special reports, Vol. 64, 1978, pages 64-68, VDE-Verlag GmbH, Berlin) each concentrator unit is arranged for a certain maximum number of subscriber stations. Preset call-in numbers are associated with the subscriber circuits by the wiring or by programming in the concentrator unit. The individual concentrator units are usually distributed round spatially separate subscriber connection areas which may be formed, for example, by residential blocks. However, different numbers of subscriber connections are actually needed in different connection areas, and furthermore the numbers can alter with time in each connection area. For this reason, cases inevitably result of poor utilisation of a concentrator unit which is too large.Conversely, cases result in which a concentrator unit proves too small, so that the local need for connections cannot be satisfied, even though the maximum number of subscriber stations which can be connected to the concentrator has not yet been reached.

An object of the invention, therefore, is to be able to distribute the whole of the available connections in a pulse code modulation concentrator, with maximum freedom of movement, to the various concentrator units and to be able to change this distribution, in a simple way, to correspond with the changing need so that all of the available connections in the concentrator may be utilised.

According to the invention, a pulse code modulation concentrator zone apparatus for a telecommunication exchange comprises a number of concentrator units each associated with a plurality of subscriber stations, each concentrator unit including a control circuit for setting up connections from and to the associated subscriber stations and a subscriber circuit for each subscriber station, each subscriber circuit being identifiable by a respective call-in number; wherein the control circuit of each concentrator unit causes extraction from the summation bit current of all of the call-in numbers selectively with respect to time and offers them at a given instant to all of the subscriber circuits of the concentrator unit, and wherein a comparator compares the call-in numbers offered with the call-in number which identifies the subscriber circuit and upon agreement between the compared numbers, activates the respective subscriber circuit to receive and transmit information, and feeds to the control circuit of the respective concentrator unit a signal reporting the responsibility of the concentrator unit for the particular callin number.

In each concentrator unit there may be provided, from the outset, enough spare places for the insertion of subscriber circuits to allow the system to be able to deal usually with the expected fluctuations in need depending upon the place and the time. In the case of a subscriber who changes his residence within the zone included in the same pulse code modulation concentrator, the subscriber circuit and the comparator associated with him can be removed from the concentrator unit hitherto responsible, and inserted in the concentrator unit which is now responsible, so that this subscriber retains his former telephone number (and call-in number) without any additional alterations.

Preferably the subscriber circuits, together with the corresponding comparator devices for the call-in numbers, are made as interchangeable plug-in units for the concentrator units, for example in the form of printed circuit boards, so that changes in the available number of connections, and/or retention of the same call-in number by a subscriber changing his residence, are readily achieved without any soldering work. Preferably, the call-in number can easily be altered on the printed circuit board by means of jumpering, a set of keys or an electronic store.

An embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block schematic diagram of a zone apparatus in accordance with the invention in a telephone exchange, and Figure 2 is a block schematic diagram of the basic structure of a concentrator unit of the apparatus.

The zone apparatus shown in Fig. 1 comprises a pulse code modulation concentrator having a number of concentrator units K1 to Kn (for example eight units), which for reasons of safety are connected in series in two rings R1 and R2 so that, in the event of failure of one ring, telephony is possible over the other ring. A plurality of subscriber stations TN is connected to each concentrator unit. The necessary "Codecs" (analogue-digital and digital-analogue converters) which convert the analogue signals from or to the handset at a subscriber station TN into digital signals for the pulse code modulation operation, and vice versa, may be provided in the subscriber stations TN or in the concentrator units K1 to Kn.The rings R1 and R2 operating on pulse code modulation are connected, where necessary, via regenerative amplifiers V1 and V2 to a zone terminal VFT which is accommodated in the exchange. The exchange VS, itself, may operate on pulse code modulation, or, in the case of the inter-position of appropriate convertors, may be a conventional exchange having space multiple and analogue signal operation.

The number of channels in the concentrator is considerably smaller than the maximum possible number of subscriber stations TN and amounts to, for example, 32 per ring, i.e. 64 in total for the two rings R1 and R2. For the sake of simplicity in the following description a concentrator having only one ring R1 may be described However, doubling of the corresponding devices for the connection of a second ring R2 and, where necessary, also doubling of the number of subscriber stations TN is possible.

In conformity with the appropriate CCITT recommendations for the 32 channels (i.e.

channels 0... 31), the 0 channel should be employed for the synchronisation of the bit current; the channels 1 to 1 5 as speech channels 1 to 15; the 1 6th channel for the exchange of information for control and signalling purposes; and the channels 17 to 31 as speech channels 1 6 to 30.

Referring to the concentrator unit illustrated diagrammatically in Fig. 2, an example of the connection of 256 subscriber stations to the 30 speech channels of a so-called PCM 30/32-system will be now described.

Fundamentally it must be ensured that in the case of setting-up of connections, enquiries and orders are always sent only from the zone terminal VFT to the concentrator units K1 to Kn, and these are then answered or executed by these units. The concentrator units therefore do not, of themselves, initiate any activity. The enquiries, orders and replies are transmitted in the 1 6th channel, which r?iay be designated the signalling channel. In this case, the enquiries and orders, but not necessarily also the replies, consist respectively of two parts which are transmitted in the signalling channels of two frames succeeding one another in time, consisting of the 32 channels.The first part (the address) contains the call-in number, which identifies a certain subscriber circuit TNS in the pulse code modulation concentrator, whilst the second part contains the information regarding the enquiry or the order.

Hitherto, in each of the concentrator units K1 to Kn the call-in numbers of the subscriber stations allocated to it were preset and unalterable. In the apparatus of the present invention the subscriber circuits with the corresponding comparator devices used for the comparison of the offered call-in numbers with a call-in number established in the respective subscriber circuit, are made as interchangeable plug-in units TE which may be plugged in to make contact in any one of the identically-wired plug-in positions in any concentrator unit.Hence, call-in numbers associated with a certain concentrator unit within the zone become established for the first time by these plug-in units and therefore by plugging-in any number of such subscriber plug-in units TE1, TE2...TEn any number of subscribers may be included in the respective concentrator unit.

Referring to Fig. 2, which shows a block diagram of a possible configuration of a concentrator unit, an ordinary mains terminal unit LE is inserted in the ring R1, incoming and outgoing sections of which are indicated by arrows. The synchronisation pulses arriving in the channel 0 are fed to a synchronisation circuit SY which establishes the working cycle of a control device ST of the concentrator unit. The incoming and outgoing sections of the ring R1 are connected through the mains terminal unit LE to a receiving bus EB and to a transmitting bus SB respectively. These are connected to a signal extraction stage SIG and to the subscriber circuits TNS1 ... TNSn, so that incoming information under the controlling action of the control device ST may be picked up either by the stage SIG or by a subscriber circuit TNS.

Following the terminal unit LE there is a bypass gate BG which is controlled by the control device ST, and upon opening connects the receiving bus directly to the transmitting bus so that incoming signals are redirected unaltered to the ring and thence to the next concentrator unit, when an item of information is either not needed by this concentrator unit or should reach all of the concentrator units connected to the ring R1. Upon blocking the by-pass gate BG, at the same time as picking up an item of incoming information by the SIG or a subscriber circuit TNS, another item of information may be fed into the transmitting bus SB as a substitute for the information which has been extracted.

If, for example, there arrives from the zone terminal VFT in the 1 6th channel an enquiry (e.g. subscriber state) or an order (e.g. ringing) addressed to a certain call-in number, during the transmission of the address, i.e.

during the transmission of the call-in number, the bypass gate BG is opened so that the callin number is passed on to all of the concentrator units. The call-in number arrives at each concentrator unit via the receiving bus EB and an input lead signal in the stage SIG which has been activated via a control lead stl by the control device ST for the pick-up of the call-in number, and gets transferred by it via a control lead st2 into the control device ST. A control device ST offers this call-in number, via a control lead st3, to comparator devices Vg1 of all of the subscriber plug-in units TE1 to TEn, and a similar offer occurs in all of the concentrator units K1 to Kn.Only the comparator device Vg1 of that subscriber circuit TNS with which is associated the call-in number offered at the time feeds a report signal to the control device ST in its concentrator unit, via a control lead st4.

Due to operation of this control device ST at the instant of the transmission of that item of information which corresponds with the enquiry or order determined by the preceding transmission of the call-in number, the bypass gate BG in the concentrator unit becomes blocked, and the stage SIG becomes activated to pick up the incoming information and, where necessary, to release an outgoing item of information.

The incoming information is then transferred, via the control lead st2, into the control device ST and is passed on by it, at a suitable instant (e.g. afterwards in the 0 chan nel), via a control lead st7, to the subscriber circuit TNS determined by the preceding callin number.

If necessary, before the picking up of the incoming information (e.g. beforehand in the 0 channel), the reply to a preceding question by a subscriber circuit TNS, determined by the call-in number, is applied via a control lead st5 to the control device ST. The reply is passed on by the device ST, via a control lead st6, to the stage SIG so that the latter can release this outgoing information, via an output lead sig2 to the transmitting bus SB simultaneously with the picking up of the incoming information.

If, in the case of an order, it is necessary to allocate a speech channel to a certain subscriber station TN, the part of the information relating to the order, following the transmission of the call-in number, contains the speech channel number allocated to this callin number. As already described, the call-in number is picked up by the signal extraction stage SIG and is transferred via the control lead st2 into the control device ST. The call-in number belonging to the allocated speech channel is thereby written by the control device ST into a random access memory RAM of the control device, in dependence upon the speech channel number.

The procedure for the speech channels 1-15 and 17-31 is similar to that for signalling in the 1 6th channel. If, in the course of the cycle, there is transmission in one of the 30 speech channels, at a given instant the call-in number allocated to this speech chan nel is read out of the memory RAM and is offered by the control device ST, via the control lead st3, to the subscriber plug-in units TE. In that case, only one single subscriber plug-in unit TE becomes activated, whereby the subscriber circuit TNS of this plug-in unit becomes connected via leads 11 and 1 2 to the receiving bus EB or to the transmitting bus SB, so that in this channel a conversation can be carried on.

The connections initiated by the exchange and by the subscriber stations TN are set up in the same way. The devices for use on termination of conversations, and for feeding ringing tones, engaged tones, dialling tones, etc., may be formed as in a normal pulse code modulation concentrator, so there is no need to describe such devices herein.

Claims (4)

1. A pulse code modulation concentrator zone apparatus for a telecommunication exchange, comprising a number of concentrator units each associated with a plurality of subscriber stations, each concentrator unit including a control circuit for setting up connections from and to the associated subscriber stations and a subscriber circuit for each subscriber station, each subscriber circuit being identifiable by a respective call-in number; wherein the control circuit of each concentrator unit causes extraction from the summation bit current of all of the call-in numbers selectively with respect to time and offers them at a given instant to all of the subscriber circuits of the concentrator unit, and wherein a comparator compares the call-in numbers offered with the call-in number which identifies the subscriber circuit and upon agreement between the compared numbers, activates the respective subscriber circuit to receive and transmit information, and feeds to the control circuit of the respective concentrator unit a signal reporting the responsibility of the concentrator unit for the particular call-in number.

2. Apparatus as claimed in Claim 1, wherein the subscriber circuits together with the corresponding comparators are made as interchangeable plug-in units for insertion into the concentrator units.

3. Apparatus as claimed in Claim 2, wherein each call-in number identifying a subscriber circuit may be set up on the plug-in unit by means of jumpering a set of switches or an electronic store.

4. Apparatus as claimed in Claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.