AU654417B2

AU654417B2 - A process for transmitting communications signals

Info

Publication number: AU654417B2
Application number: AU30259/92A
Authority: AU
Inventors: Peter Schunk; Dirk Stuhrmann
Original assignee: KE Kommunikations Elektronik GmbH and Co
Current assignee: KE Kommunikations Elektronik GmbH and Co
Priority date: 1991-12-18
Filing date: 1992-12-17
Publication date: 1994-11-03
Anticipated expiration: 2012-12-17
Also published as: DE4141725A1; CN1075837A; CH684565A5; DE4141725C2; AU3025992A; IL104106A0; IL104106A

Description

_Cs _I n: 7' L.i S F Ref: 217541

AUSTRALIA

PATENTS ACT 1990 COMPLETE SF2CIRCA7T3N FOR A STANDARD PATENT

ORIGINAL

I

f 00 o o e *o 9 a a~ 0 00B (ifl 60 0000 o a a on~ i 00 o 0 o 00 00< a e 6 r u 0 0 9040 UI 0 aa 9 a w U a 0 Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: ke Kommunikations-Elektronik GmbH Co Kabelkamp 3000 Hannover 1

GERMANY

Dirk Stuhrmann, Peter Schunk Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia A Process for Transmitting Communications Signals The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845/4 I I TECHNICAL FIELD The invention relates to a process for transmitting communications signals between at least one subscriber and at least one switching centre connected to a telephone network, wherewith the signals are transmitted as digital signals over a two-wire line between two connecting units associated with the subscriber and the switching centre, and wherein the subscriber, on the one hand, and the switching centre, on the other, are connected with the associated connecting unit via two-wire interfaces, at least one of which is configured as an analog interface (DE-Z "net," 42 (1988), Nos. 1/2, pp. 49 53).

BACKGROUND OF THE INVENTION For example, the German Fnderal Postal Authorities provide with their integrated data network (IDN) a net for transmitting data in digital form, Which net is independent of the telephone network. For example, the DATEX-P net is such a net. Apart from the IDN, other data networks with digital transmission are known. In what follows, the IDN is considered as a representative of all such networks.

The subscriber can connect to the IDN peripheral data units (DEE) the transmission rate of which may differ in dependence upon the interface oO available. Thus, a data net terminal unit (DNG) with a maximum transmission rate of 19.2 kbit/sec at the interface X.21 according to CCITT is known. But there are also known units having higher transmission rates of, say, 64 kbit/sec. For example, a direct-call net terminal unit (DAG) is such an instrument. In order to be able to transmit the signals of the DEE in an IDN, in the known method there is interconnected a data net terminating unit (DNAE) which prepares the signals of the DEEs for .0 o transmission. For example, the DNG or the DAG may be a DNAE.

In order to improve the utilization of the copper wires of existing 0 \o 30 cable lines, it is also known from the above-cited DE-Z "net" to connect, for example two, subscribers with their telephones to one line only. After digitization, the signals are transmitted between a switching centre and the subscribers at a transmission rate of, say, 144 kbit/sec./ The two digitized voice channels are transmitted in two channels of 64 kbit/sec each via a two-wire line between the subscribers and the switching centre.

The remaining so-called D channel with 16 kbit/sec is used for control purposes, FAX units may be used by the subscribers in place of telephone sets. The corresponding system has been denoted by PCM2A because two analog interfaces are available on the side of the subscriber and on the 2 744/jrb side of the switching centre.

Thus, the two systems described work with two separate nets. If a subscriber with his "digital" and "analog" instruments wishes to use both nets, he/she is connected over separate paths to them in the known method.

This requires relatively high expenditures because separate lines must be laid out between the switching centre or the switching centres and the subscriber.

SUMMARY OF THE INVENTION Thus, the problem underlying the invention is to develop the abovedescribed process further so that a subscriber's instruments can be connected with the IDN, as well as with the telephone net, over a single two-wire line.

According to the invention, the problem is solved in that at least one of the two-wire interfaces of the two connecting units is configured as a digital interface; the digital interface on the side of the subscriber is configured so that a peripheral data unit with a digital input or output can be connected via a two-wire line with an interposed data net terminating unit; and 20 a data net is connected to the digital interface on the side of the switching centre.

o ith this process, the k. qn transmission system, in which, following digitization, voice channels are transmitted in both directions via a .o0 two-wire line between a subscriber and a switching centre of the telephone net, is used in a simple way for 4he additional connection of data units with digital inputs and outputs. To this end, in the connecting units of both the -'-bscriber and the switching centre there is replaced at least one of the a og interfaces by a digital two-wire interface so that, at the subscriber, a two-wire line running to a DNAE and, at the switching centre, 30 the IDN proper can be connected to the respective digital two-wire 0:.o0: interface. Therefore, all the units of a subscriber can be connected via the existing two-wire line with the IDN or the telephone net, irrespective i of whether they are provided with a digital or an analog input or output.

The expenditures for this process are low because, in the simplest embodiment, only one A/D converter has to be replaced by a digital matching component in the two connecting units. Since the digital two-wire interface on the subscriber's side is designed for connecting a two-wire line, there is the additional advantage that greater distances can be bridged between the connecting unit and the DNAE than in the case of the X -3- 744/jrb -Y I I ii.

or V inter.aces conforming to CCITT. Ranking is greatly simplified because of the two-wire line.

In the preferred embodiment, in the two connecting units, at the digital two-wire interface and in the DNAE there is employed a transmitting unit using the ISDN transmission technique (UEI), wherewith the digital signals are converted for transmission over the respective two-wire line or in the IDN and are processed. One UEI then replaces, for example, one A/D converter in the connecting units of the subscriber and of the switching .entre.

BRIEF DESCRIPTION OF THE DRANINGS The process according to the invention is explained with reference to the drawings of an embodiment.

There show: Figures 1 to 3, various circuits in the form of block diagrams for practising the process according to the invention; Figure 4, a detail of the circuits on an enlarged scale.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1 shows diagrammatically essential parts of the known PCM2 system. These are: the switching centre VSTF of the telephone net, a 20 connecting unit VA connected to the same via an analog interface a/b, a two-wire line L, a connecting unit TA. associated with the subscriber, and a Cn -ke- MemodneaT o-P the inverr ioq here descrMbed +he S telephone or FAX unit T connected to the analog interface of the same. -weconnecting units VA and TA each have a digital two-wire interface Uko in addition to the analog interface a/b.

a A DNAE, to which a DEE is cdhnected, is connected via a two-wire line with the Uko interface of the TA. The Uko interface of the VA is connected with a switching centre VSTD of the data network IDN. The two switching centres VSTF and VSTD, which are shown as separate centres in the drawings, could be integrated in one location.

The DEE has, for example, an X.21 or a V.24 interface according to CCITT with a maximum transmission rate of 19.2 kbit/sec. This transmission rate is increased to 24 kbit/sec by, say, a DNG. The data of the DEE can be transmitted via the one digital channel of 64 kbit/sec of the PCM2 system illustrated in Figure 1. Since this channel is not used to its full capacity, additional data, which are fed into, say, the DNG, could be transmitted. In this system, the 64 kbit/sec of a channel compare with a total transmission rate of 144 kbit/sec used. The process according to the invention is not limited to this transmission rate.

In principle, the circuit shown in Figure 2 ',orks in the same way, S, 44/jrb _1 L I__ wherein the connecting units VA and TA are provided with three analog interfaces a/b and a digital two-wire interface Uko. The Uko interface of VA is connected with the VSTD, whereas the VSTF is connected to the three a/b interfaces. Telephones or telecopiers T are connected to the a/b interfaces of the TA at the subscriber. The DEE is connected with the Uko interface via a DNG and the two-wire line Z. Here four digital channels with 32 kbit/sec are available at a transmission rate of 144 kbit/sec in the four-wire line L.

When a DAG with an input or output of 64 kbit/sec is to be used in place of the DNG, two of the analog interfaces a/b are replaced by a digital interface as per Figure 3. The data of the DEE are transmitted via two combined 32 kbit/sec channels to the IDN or vice versa. There remain two analog interfaces a/b for telephones or telecopiers T.

In order to obtain matching of the digital two-wire interfaces, in the preferred embodiment UEIs are used in the connecting units VA and TA, as well as in the DNG or the DAG as shown in Figure 4 for the subscriber side. The UEI processes the signals in two directions of transmission in such a way that the arriving signals are processed by the respective DNAE and the signals emitted from the DNAE can be transmitted through the two-wire lines L and Z and the IDN.

I t When a DEE is connected to a DNG, the UEI according to Figure 4 has o the following functions: .oO, Data inputted from the DEE at a transmission rate of at most 19.2 oo kbit/sec are set on an increased transmission rate of 24 kbit/sec in the 9 0 DNG by adding so-called envelope bits and are serially and in synchronism accepted by the UEI. They are combined into three bits in each case and oo. o given an additional control bit. The 4-bit data group obtained in this way is fitted into a time slot on the Uko interface and thereafter serially outputted. In the direction of reception, the data group is picked out of 30 a time slot (serial-parallel conversion), the control bit is removed, and *.go the remaining 3 parallel bits are serially outputted to the DNG. After removal of the envelope bit, the received data are available for the DEE at 04: 'a transmission rate of 19.2 kbit/sec.

S735 5 744/jrb

Claims

1. A process for transmitting communications signals between at least one subscriber and at least one switching centre connected to a telephone network, wherewith the signals are transmitted as digital signals over a two-wire line between two connecting units associated with the subscriber and the switching centre, and wherein the subscriber, on the one hand, and the switching centre, on the other, are connected via two-wire interfaces with the associated connecting unit, at least one of which is configured as an analog interface, characterized in that at least one of the two-wire interfaces of the two connecting units (VA, TA) is configured as a digital interface (Uko); the digital interface (Uko) on the side of the subscriber is configured so that a peripheral data unit (DEE) with a digital input or output can be connected via a two-wire line with an interposed data net terminating unit DNAE); and a data net is connected to the digital interface (Uko) on the side of othe switching centre.

2. The process according to Claim 1, characterized in that at each digital interface (Uko) of the two connecting units (VA, TA) and in the data net terminating unit there is interposed a transmitting unit (UEI) by which the signals are converted in each of the two directions of transmission and processed for transmission.

3. A process for transmitting communications signals, substantially Se.as hereinbefore described with reference to the accompanying drawings. «e DATED this SEVENTEENTH day of AUGUST 1994 ke Kommunikations-Elektronik GmbH Co. Patent Attorneys for the Applicant SPRUSON FERGUSON 6 744/jrb A Process for Transmitting Communications Signals Abstract There is described a process for transmitting communications signals between at least one subscriber and at least one switching centre (VSTF) connected to a telephone network, wherewith the signals are transmitted as digital signals over a two-wire line between two connecting units (TA, VA) associated with the subscriber and the switching centre (VSTF). The subscriber on the one hand, and the switching centre (VSTF), on the other, are connected with the associated connecting unit (TA, VA) via two-wire interfaces, at least one of which is configured as an analog interface At least one of the two-wire interfaces of the two connecting units (TA,VA) is configured as a digital interface (Uko). The digital interface (Uko) on the side of the subscriber is configured so that a peripheral data unit (DEE) with a digital input or output can be connected via a two-wire line with an interposed data net terminating unit (DNG), and a data net is connected to the digital interface on the side of the switching centre. 0a 0 o 0:0 Figure 2 il II KRS/274T