IL105178A

IL105178A - Telecommunication switching system

Info

Publication number: IL105178A
Application number: IL10517893A
Authority: IL
Original assignee: Kommunikations Elektronik
Priority date: 1992-05-16
Filing date: 1993-03-26
Publication date: 1996-01-31
Also published as: DE59309919D1; EP0570749A2; ATE188591T1; ES2140425T3; IL105178A0; EP0570749A3; EP0570749B1; DE4216266A1

Abstract

A circuit arrangement for transmitting telecommunication signals between a number of subscribers and an exchange of a telephone network in both directions of transmission is specified. For each subscriber, a system unit with an analog and a digital connection side is provided both on the subscriber side and on the side of the exchange, the analog connection side of which is in each case connected to a subscriber or to a selector allocated to this subscriber in the exchange. All system units are connected with their digital connection sides to a multiplexer arranged at the subscribers, on the one hand, and at the exchange, on the other hand. The multiplexers are in each case connected to converters, which are connected to one another via the two-wire line. For switching-through and allocation of the voice channels, each multiplexer is connected to an intelligent control unit and the two control units are connected to one another via the converters and the two-wire line.

Description

TELECOMMUNICATION SWITCHING SYSTEM Abstract of Disclosure There is proposed a switching system for the transmission of communication-technical signals between several subscribers and one exchange of a telecommunication network. For each one of the subscribers there is provided, both at the subscribers side as well as exchange side, a system unit with analogue and a digital connection side, the analogue connection side of which is connected at a time with one subscriber, respectively with a dialling means associated with that subscriber at the exchange. All system units are connected by way of their digital connection sides with a multiplexer which is provided both at the subscribers and as well as at the exchange, with a converter. To each of the multiplexers there is connected a converter which converters are interconnected via the twin wire conduit. For through-switching and translation of speech channels each multiplexer is connected to an intelligent control unit and both control units are connected with each other via the converters and the twin wire conduit.

Field of the Invention The present invention relates to a switching system for use in transmitting communication-technical signals between several subscribers and an exchange of a telecommunication network at both transmission directions, there being provided, both at each subscriber points, as well as at the exchange, system units with an analogue and a digital connection side, between which signals are transmitted via a twin wire conduit and at which both at the subscribers 1 side, as well as at the exchange analogue intersections are available (Technical Information PCM4 - System of re Kommunikations- Elektronik GmbH & Co, Hanover 07/91) Such a procedure is practiced for the sake of better exploitation of cable arrangement which comprise copper conductors. At existing procedures, according to the above cited Technical Informations, four subscribers' telephones are connected to a twin-wire conduit with intermission of said system units. The transmission of signals takes place between an exchange and a subscriber following digitali-zation, at a transmission rate of 144 kbit/m as effective work rate. The digitalizited speech channels are transmitted between the subscribers and the exchange or vice versa in four channels of each 32 kbit/m via the twin wire conduit. The remaining, so called D-channel with 16 kbit/m is employed for control purposes. At the subscribers' locations in lieu of telephone apparatus modems or telefax devices may be connected.

The respective system is designated as "PCM-4" since at the system units at the connection side of subcribers and at exchange side there are provided four analogue intersection points. The letters "PCM" indicate the well known method of Pulse-Code-Modulation.

Object of Invention It is the main object of the invention to further develop the above described procedure, such that at the same transmission rate more than four subscribers could be connected to the telecommunication network without thereby impairing the quality of transmission.

Short Summary of Invention The said object is obtained, according to the invention thereby that; for each subscriber is provided a system unit, both at subscriber's side as well as at the exchange side, the analogue connection side of the said system unit being connected at a time with one subscriber, or respectively with a dialling means at the exchange which is associated with that subscriber, all system units are connected at a time by their digital connection sides to a multiplexer provided on the one hand at the subcribers end at the exchange on the other hand.

To each of both multiplexers there is connected a converter which converters are interconnected by the twin wire conduit , each multiplexer is connected with an intelligent control unit for translation the through switching of transmission paths between subscribers and the exchange and both control units are connected with each other by means of the converters and the twin wire conduit.

By means of such a switching system the transmission paths are translated to subscribers by way of the control units. None of the subscribers is permanently associated with a speech channel: the subscribers are selectively apt to become connected to the exchange via the multiplexer.

Assuming that not more than four subscribers would use their telephones simultaneously those are through connected successively in the same order as they lift the receiver or are being called. At no change relative to the generally known, there are being transmitted maximally four speech channels with e.g. 32 kbit/m, such that at all conversations the transmission quality of the PCM-4 system is retained.

Both control units can exchange information as to which transmission path is being passed through or is to be passed through.

Practical examples of operating the invention may be gathered from ancillary claims.

Practical embodiments of the invention are illustrated by the accompanying drawings, which show by; Fig. 1 Schematical view of a block diagram of a switch- ching system according to the invention, while, Fig. 2 is a variation of the arrangement of Fig. 1.

The drawings depict the use of the inventive switching system for four, subscribers. There should be in practice at least five subscribers.

Each of the subscribers Tl to T8 is connected by his or her analogue device (telephone or telefax) with one of the system units ST1 to ST8, practically with the connection side thereof indicated by reference letters a/b. All system units ST1 and ST8 are connected, according to Fig. 1, at their digital connection sides, with one multiplexer Ml.

Multiplexer Ml is connected with converter Ul from the digital Uko intersection of which a twin wire conducter ASL leads to a converter UZ of an exchange VST.

The converter U2 is connected with a multiplexer M2 at eight digital terminals of which are connnected eight system units SV1 to SV8 at their digital connection sides. The again with a/b referenced analogue connection sides of system units SV1 to SV8 are connected to selectors Wl to W8 which are located at the exchange VST. Each selector Wl to W8 is coordinated to one of subscribers Tl to T8.

The converters Ul to U2 substantially have two functions. Therefore they are partitioned by a line dividing them into two parts. At one function, i.e. CI and C2 respectively the data rate of signals is being reduced or increased, respectively. The coding change taking place thereby may be effected e.g. by means of the well known ADPCN -procedure. Thus, by way of an example, the speech channel emanating from multiplexer Ml at 64 kbit/s could be recoded by the converter Ul to a speech channel of 32 kbit/s.

Recoding by the function C2 of the converter U2 takes place in reverse direction. The same is the case reversably for the other transmission direction. At its second function Al or A2 respectively the signals emanating from functions CI and C2 or those to be transmitted by them or data flows are converted or reversed into values appropriate for transmission via twin wire conductor ASL.

The functions CI or C2 respectively of converters VI or V2 could be placed according to Fig. 2, intermediate the system units ST1 to ST8 and multiplexer Ml, as well as intermediate the system units SVl to SV8 and multiplexer M2. The functions Al and A2 remain unaffected.

In each one of the system units ST1 to ST8 at subscribers' site there is provided a current detector ID while in each one of the system units SVl to SV8 at the exchange site VST there is located a voltage detector VD. All current detectors ID are connected to an intelligent control unit SE1 which is connected to multiplexer Ml. To the intelligent control unit SE2 which, as stated, is connected to the multiplexer M2 there are connected all voltage detectors VD.

That connection is shown at each time only in respect of one construction part ID and VD. The control units SE1 and SE2 are interconnected via the function Al and A2 of converter Ul and U2 and the twin wire conduit AS.

Information exchange between the two control units SEl and SE2 is made possible e.g. via the D-channel.

Multiplexers Ml and M2 are, per se, well known parts for interspersal of digital transmission, channels in the time - multiplex method. In the present case they are provided with multiplexer steps. Microcontrollers or gaterelays, may be used to serve as control units SEl and SE2.

The switching arrangement according the invention function as depicted by the example of Fig. 1 as follows: Starting from the situation at which none of the subscribers Tl to T8 does talk on his telephone apparatus, it is assumed that subscriber Tl wishes to speak, he lifts the receiver, the current detector ID of his system unit records the now flowing slip current and issues an appropriate digital information to control unit SEl. The latter sends a control signal to multiplexer Ml which apportions a free speak channel to subscriber Tl. For subscriber Tl thus becomes available a channel of e.g. 64 kbit/s which is available at the digital connection side of system unit ST1 and is put-through by the multiplexer Ml. The 64 kbit/s speech channel is connected by the converter VI into a 32 kbit/s - speech channel and is transmitted via the twin wire conduit AS to the converter V2. There the 32 kbit/s speech - channel is again converted into a 64 kbit/s speech channel and is conducted by multiplexer M2 to the system unit SV1. By means of the selector Wl the subscriber Tl is connected then to the telecommunication network which - in turn - is connected to exchange point VST, the said telecommunication network being symbolized by the double arrow P. So that the multiplexer M2 does direct the arriving speech channel to the proper system unit or puts through the correct selector respectively, the control unit SE2 is given the proper information via the channel by the control unit SEl.

Putting through the transmission path in the event of subscriber Tl being called is effected in the manner of the described procedure. The call arriving at the selector Wl is recorded by the voltage detector VD of system unit SV1. The control unit SE2 receives a corresponding digital information. It contacts multiplexer M2 and informs the control unit SEl. From the latter the multiplexer Ml is contacted. The converters Ul and U2 operate in the manner of foregoing descriptions.

Should during the period of subcriber's Tl talking, also subscriber T3 desires to telephone an addition speech channel, with transmission rate of 32 kbit/s at the Uxo intersection will be coordinated to him via a stil free speech channel. The next following subscriber who desires to telephone will be given a third, free speech channel if the two subscribers Tl and T3 are still talking. For a fourth subscriber, there remains - if the other three subscribers are still talking - the fourth free speech channel. As long as these four subscribers talk, or other four subscribers do telephone, further subscribers cannot be connected to exchange VST and also would not be available to callers from the telecommunication network. Such an event would most probably not arise under normal conditions, especially not if subscribers Tl to T8 are chosen in accordance with knowledge of their habits, how long and how often they do telephone.

Control units SEl and SE2 record via current detectors ID or voltage detectors VD whenever one of the subscribers concludes his telephone talk.

The respective transmission path would then be free again. It can be put through for the next following subscriber who wishes to telephone or is being called.

The above clarifications given in respect of telephones or telephoning are applicable without change also for the event of subscribers Tl to T8 use modems or telefax apparatus .

Claims

CLAIMS ;

1. Switching system for use in transmitting communication-technical ^signals between several subscribers and an exchange of a telecommunication network at both transmission directions, there being provided, both at each subscriber points, as well as at the exchange, system units with an analogue and a digital connection side, between which signals are transmitted via a twin wire conduit and at which both at the subscribers' side, as well as at the exchange analogue intersections are available characterised thereby that for each subscriber is provided a system unit, both at subscriber's side as well as at the exchange side, the analogue connection side of the said system unit being connected at a time with one subscriber, or respectively with a dialling means at the exchange which is associated with that subscriber, all system units are connected at a time by their digital connection sides to a multiplexer provided on the one hand at the subcribers end at the exchange on the other hand. To each of both multiplexers there is connected a converter which converters are interconnected by the twin wire conduit, each multiplexer is connected with an intelligent control unit for translation the through switching of transmission paths between subscribers and the exchange and both control units are connected with each other by means of the converters and the twin wire conduit.

2. Switching system according to claim 1 characterised thereby that eight subscribers (Tl - T8) are being converted.

3. Switching system according to claims 1 and 2, characterised thereby that In each system unit (ST1 to ST8) at the subscribers side there is provided a current detector (ID) and at each system unit (SVl - SV8) at the side of the exchange (VST) there is provided a voltage detector ( VD ) , and all current detectors (ID) and all voltage detectors (VD) are connected with respective control unit (SEl - SE2) . Tel Aviv, Attorneys for Applicants.