GB2059720A - Improvements in or relating in to switching apparatuses for connecting information sources together - Google Patents

Abstract

A switching apparatus which may be used as a telephone exchange comprises a switching field block 1, an interconnecting circuit block 2, an external peripheral block 3, and a control circuit block 4. The switching field block 1 comprises a switching field 5, a connecting path set-up circuit 6, a connection path hold circuit 7, a connection path clearing circuit 8, an information converter 9, a supply voltage converter 10, and a control interface unit 11. The interconnecting circuit block 2 comprises signal transmitter/receiver 12, a signal transmitter/receiver control 13, a scanner 14, a supply voltage converter 16, a signal generator 15, and a control interface 17. The external peripheral block 3 comprises a non-controlled peripheral device 18, a controlled peripheral device 19, and a control interface unit 20. The control circuit block 4 comprises a control circuit 21, data inputs 23 and data outputs 24, check devices 25, a supply voltage converter 22, and a peripheral interface unit 26. <IMAGE>

Description

SPECIFICATION Improvements in or relating to switching apparatuses for connecting information sources together This invention relates to a switching apparatus for connecting information sources together.

Such an apparatus may, for instance, be used as a telephone exchange.

The appearance of computer techniques has required a new classification of the traditional switching functions in telephone switching techniques. As a result of new technical devices, the different functions of switching, the information conversion and storage, and the logical functions have been divided. This division meant first of all a quantitative reclassification.

In accordance with newly introduced devices, the control unit has been separated in the switching apparatus, and it has the functions primarily of logic operations and information storage. The switching and logic functions and partly the information conversion function are performed by peripheral devices, switching field circuits and interconnecting circuits (subscriber circuits, interconnecting line circuits, code transmitter/receiver circuits (i.e. modems) etc. These different functions constitute the entire set of switching functions. The connection between the two main units is provided by the peripheral interface system.

Such systems are known for a switching apparatus having three main functional units as follows: the control unit, the peripheral interface unit and the peripheral device. In known systems, e.g. in telephone exchanges of Telefonbau and Normalzeit (see TN Nachrichten 1978) the processing capacity of the control circuit is law, and a pre-processor unit is therefore provided for performing frequently repeated logic functions, releasing in this way the central control unit.

There are known systems e.g. System EWS of Siemens AG, having a single control unit.

Possibly complemented with a reserve control unit.

In other known systems, control circuits are arranged in hierarchy (System E10), or the controlling functions are distributed (e.g.

AXE).

From among the possible configurations, in a given case, that one is chosen which corresponds to the available circuit elements and equipment. Furthermore, the desired capacity of the switching apparatus and the available circuit elements and the assortment of equipment together determine this decision in this respect.

The above-mentioned methods of building up a system are used in the case of a given technical level, a known assortment of circuit elements, outlined requirements and a given capacity range. However, the evolution of telephone switching techniques raises various demands on the switching apparatus. The objective is to realize connection between equipment of different types. This means further objectives concerning the fulfilment of various functions. The quantitative demands concerning the switching apparatus vary according to the number of information sources to be connected and the number of paths to be set up in a unit of time.In the case of law capacities, it is uneconomical to fulfil various requirements by means of a single common control unit, since it requires a control unit of high capacity, or in the case of a control unit of law capacity, the upper unit of the control unit's capacity will be law. This is the case also when a system contains more than one control unit or when in a hierarchical system the number of the units taking part in this hierarchy is not enough. The embodiment of the peripheral devices depends on the capacity of the switching apparatus. The peripheral interface circuits have also various embodiments depending on the quantity of information to be transmitted.

The elements and techniques applied in telephone switching techniques change and develop continuously. This development is not equal in the assortment and technology of the circuit elements of units performing different functions. The elements and technologies of new types are not only far more reliable and smaller with lower power consumption, but they offer the possibility of more economical realization. It requires extraordinarily high costs and much time to reconstruct wholly all the functional units of a switching apparatus.

Such switching apparatuses are expected to operate for 25 to 40 years, but the demands on their qualitative and quantitative performance may change during this period. These qualitative and quantitative demands should be met by the enlargement of the existing apparatus. In the above case, the construction corresponding to the technology and assortment of circuit elements being available 1 5 to 20 years earlier should be conserved. In other cases either the entire switching apparatus, or a predominant part of it, should be replaced.

According to the invention, there is provided a switching apparatus for connecting information sources together, comprising a switching field block, an interconnecting circuit block, an external peripheral block, and a control circuit block, the switching field block comprising a switching field, a connection path set-up circuit, a connection path hold circuit, a connection path clearing circuit, a supply voltage converter, an information converter, and a control interface unit, the interconnecting circuit block comprising a signal transmitter/receiver, a signal transmitter/receiver control means, a scanner, a supply voltage converter, a signal generator, and a control interface unit, the external peripheral block comprising a non-controllable peripheral device, a controllable peripheral device, and a control interface unit, and the control circuit block comprising a control circuit, a supply voltage converter, a data input, a data output, a check unit, and a peripheral interface unit, the switching field block being connected to the control circuit block and to the interconnecting circuit block, the interconnecting circuit block being connected to the switching field block, to the external peripheral block, and to the control circuit block, the external peripheral block being connected to the control circuit block and to the interconnecting circuit block, and the control circuit block being connected to the switching field block, to the interconnecting circuit block, and to the external peripheral block.

It is thus possible to utilize steadily the advantages resulting from the evolution of technology and circuit elements, even in the case when such evolution does not affect in equal measure all the functional units.

It is also possible to provide a switching apparatus allowing units made by different technologies and of different circuit elements to cooperate with each other. Therefore the switching apparatus can be adapted, both in its geometric dimensions and technology, during a long period to the requirements and possibilities given by evolution.

Such a switching apparatus can be provided in modular construction, so that the functional blocks can be constructed independently of each other. The various functional blocks can be realized by using different technologies and different assortments of circuit elements.

The invention will be further described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of a switching apparatus constituting a preferred embodiment of the invention; Figure 2 is a block diagram of a switching apparatus constituting another preferred embodiment of the invention; and Figure 3 is a block diagram of a further preferred embodiment of the invention.

With reference to Fig. 1 of the drawings, the switching apparatus comprises four different blocks, namely a switching field block 1, an interconnecting circuit block 2, an external peripheral block 3, and a control circuit block 4.

The switching field block 1 comprises a switching field 5, a connection path set-up circuit 6, a connection path hold circuit 7, a connection path clearing circuit 8, an information converter 10 and a control interface unit 11.

The mode of operation of the switching field block 1 can be understood on the basis of knowing the mode of operation of the interconnecting circuit block 2, the external peripheral block 3 and the control circuit block 4 as well in the broad lines. The switching field block 1 serves for setting-up, holding and clearing connection paths. In accordance with this, the switching field 5 constitutes the main unit of switching field block 1. The switching field 5 has the function of connecting the circuits at its inputs to its outputs. In order to connect the selected switching field input with the desired switching field output, it is necessary to operate the switching field 5 according to given rules. This function is fulfilled by the connection path set-up circuit 6.The switching field 5 holds the state generated by the connection path set-up circuit 6 during the period of e.g. telephone calls. The status of the switching field 5 is reserved during the period of a telephone call by means of the connection path hold circuit 7.

This connection path hold circuit 7 may be contained in the switching field 5 partly or wholly, depending on the arrangement of the switching field. In the case, for example, when the elements of the switching field 5 have magnetic hold circuits, these elements retain their status after having been set-up, so that additional hold circuits are not necessary.

When a conversation is over, the connection path set up in the switching field 5 is cleared. This task is performed by the connection path clearing circuit 8. Where the elements of the switching field 5 do not contain the hold functions, these functions can be taken over by the connection path hold circuit 7. When the function of holding the switching field 5 is realized with holder current, then connection is automatically broken by the switching-off of the holder current, that is, the connection path set up in the switching field 5 is cleared. Also, no additional connection path clearing circuit 8 is necessary.

The switching field 5 may basically provide the transmission of useful information (e.g.

voice) in two ways. In a first case, the transmission takes place in analogous form, without converting the useful information; in a second case, the information is transmitted in a converted form, e.g. in digital pulses. In the first case the information converter 10 has a function of impedance matching. In the second case it has additional functions, namely the conversion of the information into the wanted form, coding when necessary, and information reconversion, that is, decoding.

The preferred embodiment of the information converter 10 depends on the above-mentioned functions to be met.

The switching field block 1 is not able in itself to meet logic functions. The selection of the connection path and the designation of switching elements taking part in the connection path are the functions of the control circuit block 4. The control circuit block 4 transmits the necessary information to the switching field block 1 in the form of an appropriate code. The communication between the switching field block 1 and the control circuit block 4 is provided by means of the control interface unit 11. The control interface unit 11 is connected to the control circuit block 4 via a bus system. The bus system should contain address and data transmission units. When the address and data are known, the control interface unit 11 addresses and supplied the units of the switching field block 1 described above with the data necessary for their operation.

As previously mentioned, and as may be seen from the mode of operation of the switching field block 1, its elements may be realized in various forms. These elements may differ from each other not only in their geometric sizes and operational parameters, but in the values of supply voltages necessary for their operation. The switching apparatuses are operated suitably from a given supply voltage, either of 48 V or of 60 V. The internal supply voltages of the switching field 1 are generated by means of the supply voltage converter 9.

This supply voltage converter 9 generates the voltages necessary for the operation of the various elements from the supply voltage by either 48 V or of 60 V.

The switching field block 1 is connected to the interconnecting circuit block 2 via its information converter 10, and to the control circuit block 4 via its control interface unit 11.

For the sake of simplicity, it is not shown that this block is connected to the external power supply via its supply voltage converter 9. The interconnecting circuit block 2 consists of a signal transmitter/receiver 12, a signal transmitter/receiver control 13, a scanner 14, a signal generator 15, a supply voltage converter 1 6 and a control interface unit 1 7.

The interconnecting circuit block 2 has the function of connecting the interfacing external peripheral devices and various equipment to the switching apparatus.

The switching and information conversion functions are met by the signal transmitter/receiver 1 2. The construction and circuit realization of the signal transmitter/receiver 1 2 are determined by the characteristics of the external equipment connected thereto. The switching apparatus has the advantage that the signal transmitter/receiver 1 2 communicates only with a given single external equipment or external peripheral device. Therefore the signal transmitter/receivers 1 2 are essentially realized with simple analog-to-digital or digitalto-analog converters.The signal transmitter/ receiver 1 2 has no logic functions, it is operated, when a signal is being transmitted, by means of the signal transmitter/receiver control 1 3. The simple construction of the signal transmitter/receiver 1 2 makes possible to construct the signal transmitter/receiver control 1 3 with entirely the same elements. The function of the signal transmitter/receiver control 1 3 is to provide an interface means between the control circuit block 4 of high rate of operation and the signal transmitter/ receiver 1 2 of lower rate of operation.

The signal transmitter/receiver control 1 3 comprises buffer and driver (control) units.

With the appropriate design of the driver circuit and the signal transmitter/receiver 1 2 it can be achieved that the driver circuits and naturally the buffers have entirely the same construction, independently from the construction of the signal transmitter/receiver 1 2.

This design has the advantage that, in the case of various peripheral device connections, only the signal transmitter/receiver 1 2 is to be redesigned and realised according to the new connections. The signal transmitter/receiver 1 2 converts the input signals into digital information. The scanner 14 receives these digital signals and transmits them to the control circuit block 4, depending on the commands arriving therefrom. The scanner 14 may comprise gate circuits arranged in matrix, the outputs of the gate circuits being connected to the control interface unit 1 7. In case of received signals, the scanner 1 4 meets the tasks resulting from the time (rate) differences, on principle of sampling.

In telephone techniques, it is usual that a part of the signalling tones are analog signals, often of voice frequency. These signalling tones are in general internationally standerized signals. The construction of the signal transmitter/receiver is highly simplified, when the analogous signals are generated by means of independent generators and the signal transmitter/receiver 1 2 switches these generators as needed. The signal generator 1 5 has the function of generating different analogous signals (dialling tone, ringing voltage, etc).

The interconnecting circuit block 2 can be realized with various circuit elements and circuit units. These units, as already mentioned in connection with the switching field block 1, can be operated from various supply voltages.

The supply voltage converter 1 6 has the function of generating all the voltages needed for the operation of the interconnecting circuit block 2, by conversion of the external supply voltages either of 48 V or of 60 V.

The units of the interconnecting circuit block 2 described before have no independent logic functions. These units can be operated by means of the commands of the control circuit block 4 and they supply information only upon a special command of the control circuit block 4. The control interface unit 1 7 provides communication between the interconnecting circuit block 2 and the control circuit block 4. The control interface unit 1 7 is connected to the control circuit block 4 via a special bus system. This bus system comprises units for transferring both address and data.When the address and data are known, the control interface unit 1 7 addresses the signal transmitter/receiver unit and supplies it with data necessary for its operation, and determines and addresses the wanted row in the matrix of the scanner 14.

The external peripheral block 3 has the function of uniting the peripheral devices which constitute parts necessary for the operation of the switching apparatus, but do not belong directly to the basic functions of the switching apparatus. The external peripheral block 3 comprises a non-controlled peripheral device 18, a controlled peripheral device 1 9 and a control interface unit 20. The noncontrolled peripheral device 1 8 communicates only with the interconnecting circuit block, via the signal transmitter/receiver 1 2. The noncontrolled peripheral device 1 8 comprises signal transmitter/receiver and signal generator units, buffers, displays, logic units and supply voltage converters if necessary.The connection between the con-controlled peripheral device 1 8 and the interconnecting circuit block 2 is similar to that between, for example, a telephone set or other switching apparatus and the interconnecting circuit block 2. The non-controlled peripheral device 1 8 can be e.g. a dictaphone (dictating machine), a paging device etc.

The controlled peripheral device 1 9 comprises a signal transmitter/receiver and generator units, buffers, displays, and control units and furthermore has input and output connections to the control interface unit 20. It can be provided with a supply voltage converter if necessary. As with the non-controlled peripheral device 18, the controlled peripheral device 1 9 has the function of meeting tasks which determine basically the operation of the switching apparatus, but which do not belong directly to the switching apparatus. The controlled peripheral device 1 3 has either no independent logic functions or only some less important ones, its operation being basically controlled by the commands of the control circuit block 4.The controlled peripheral device 1 9 can be for example some sort of operator's device having complicated functions, some types of chief-secretary equipment, etc.

The controlled peripheral device is matched to the control circuit block 4 by means of the control interface unit 20. The control interface unit 20 is connected to.the control circuit block 4 via a special bus system. This bus system should comprise address and data transfer units. When the address and data are known, the control interface unit 20 addresses the controlled peripheral device 1 9 and supplies it with data necessary for its operation, and furthermore interrogates the controlled peripheral device 1 9. The voltage necessary for the operation of the external peripheral block 3 is provided by an external supply voltage either of 48 V or of 80 V.

The control circuit block 4 comprises control circuit 21, a supply voltage converter 22, a data input 23, a data output 24, a check unit 25 and a peripheral interface unit 26.

The control circuit block 4 has all the logic functions necessary for the operation and maintenance of the switching apparatus and for the localization of errors. The control circuit block 4 has also the functions of storing data representing the characteristics of the switching apparatus and data containing information concerning the current status of connection paths and the change of status.

A general purpose computer, or special task oriented equipment can be used as the control circuit 21. The control circuit 21 comprises besides the (data) processing circuitry (e.g.

various kinds of registers, logic circuits, instruction registers, etc), store devices for programs, data store media and store media usable for meeting store functions necessary during the processing. Depending on its type, the control circuit 21 can have various data inputs 23 having the function of reading data and programs into the corresponding store media of the control circuit 21. It often occurs that during operation information is required about the status of the switching apparatus, the processes run down and the connection paths. This information is provided at the data output 24. During the operation of the control circuit block, the check unit 25 is necessary for several purposes, for example for detecting and locating errors and for checking the correct operation.The check unit 25 has the function of facilitating the tracing of the operation of the control circuit block 4 and the location of possible failures and errors.

The control circuit block 4 is connected to the switching field block 1, the interconnecting circuit block 2 and the external peripheral block 3. The connection is realized by means of the peripheral interface unit 26 via the above-mentioned bus system. The peripheral interface unit 26 is peculiar in that it possesses two identical outputs, so that it can be connected to two separate bus systems even in non-duplicated mode-of-operation. the output 30 of the peripheral interface unit 26 is connected to the control interface units 11, 1 7 and 20 described in relation to the switching field block 1, the interconnecting circuit block 2 and the external peripheral block 3.

the output 31 of the peripheral interface unit 26 is connected via another bus system either to further control circuit blocks 4 or to various test or check devices, depending on its function. The outputs 30 and 31 of the peripheral interface unit 26 are designed so that they contain both address bus units and the duplex data bus units.

Two examples of a switching apparatus will now be described.

With reference to Fig. 2 of the drawings, a switching apparatus comprises at most four switching field blocks 1, at most four inter connecting circuit blocks 2, at most one external peripheral block 3 and one control circuit block 4. The cooperation between the blocks used in the switching apparatus is shown in Fig. 2. Each switching field block 1 is connected to all the interconnecting circuit blocks 2. The units of the.external peripheaal block 3 can be connected at will to the various interconnecting circuit blocks 2. In the example shown the output 31 of the peripheral interface unit 26 of the control circuit block can be connected to various test and check devices.

The number of both the switching field blocks 1 and the interconnecting circuit blocks 2 may be less than the maximal four. The switching apparatus in the example comprises switching field blocks 1 with switching fields 5 having 1 28 inputs and 64 outputs. The communication between the switching fields 5 is realized via the signal transmitter/receivers 1 2 of the interconnecting circuit block 2. The interconnecting circuit block 2 in the example is designed so that it is capable of operating and supplying 1 28 + 32 signal transmitter/ receivers 1 2. One peripheral interface output of the control circuit block 4 is connected to a test and check unit.

Fig. 3 shows another arrangement of switching apparatus. This arrangement is capable of connecting a large number of information sources. The switching apparatus comprises separate units Al . . . An comprising switching field blocks 1, interconnecting circuit blocks 2, external peripheral blocks 3 and control circuit blocks 4. The connections between the separated units A, . . . An are realised by means of the bus system formed by the outputs 31 of the peripheral interface units 26 of the control circuit blocks 4, and by means of connections 32 and 33 between the switching field blocks 1 and the interconnecting circuit blocks 2. Each of the separated units A, . . . An has generally the arrangement illustrated in Fig. 2.The realization and operation can be facilitated by using a special separate unit B in the switching apparatus.

This unit B is designed to have only a single control circuit block 4, which is connected to the above-mentioned bus system via the output 30 of the peripheral interface unit 26, and the output 31 can be connected to various test and check devices. This arrangement comprises several control circuit blocks 4 and connection field blocks 1 connected separately to each of them, interconnecting circuit blocks 2, external peripheral blocks 3, thus providing a multiprocessor switching apparatus of high capacity, the test, check and operation of which can be performed by means of the control circuit block 4 of the above mentioned separate unit B designed particularly for this purpose. In this embodiment, each separate unit A1. . .An comprises at most two switching field blocks 1, at most four interconnecting circuit blocks 2, at most one external peripheral block 3, and one control circuit block 4.

In this switching apparatus, the switching field 5 of each switching field block 1 is designed to have 256 inputs and 1 28 outputs and/or 1 28 inputs and 1 28 outputs. The outputs 31 of the peripheral interface units 26 of the control circuit blocks 4 in the units A, . . . An are commoned and connected via a bus system to the outputs 30 of the peripheral interface unit 26 in the control circuit block 4 of the separated unit B. The output 31 of the peripheral interface unit 26 in the control circuit block 4 of the unit B can be connected to test and check devices.

Thus, such switching apparatus is especially suitable for use as various devices in telephone technology, particularly as telephone exhanges where the sizes and capacities of the switching apparatuses are different and the apparatuses are required to co-operate with other devices. It can be seen that between the suitably designed functional blocks there are a minimal number of well-definable connections. By regulating these connections and keeping these rules the functional blocks can be realized independently of each other.

This latter fact makes it possible for the functional blocks to be further developed independently of each other, according to the available technology and circuit components. The blocks of the switching apparatus may even differ if they meet the same function. Thus, an advantage of such apparatus is that the switching apparatus, in the course of its lifetime of 25 to 40 years, can be enlarged with functional blocks made to the highest level of current technology.

Claims (9)

1. A switching apparatus for connecting information sources together, comprising a switching field block, an interconnecting circuit block, an external peripheral block, and a control circuit block, the switching field block comprising a switching field, a connection path set-up, a connection path hold circuits, a connection path clearing circuit, a supply voltage converter, an information converter, and a control interface unit, the interconnecting circuit block comprising a signal transmitter/receiver, a signal transmitter/receiver control means, a scanner, a supply voltage converter, a signal generator, and a control interface unit, the external peripheral block comprising a non-controllable peripheral device, a control lable peripheral device, and a control interface unit, and the control circuit block comprising a control circuit, a supply voltage converter, a data input, a data output, a check unit, and a peripheral interface unit, the switching field block being connected to the control circuit block and to the interconnecting circuit block, the interconnecting circuit block being connected to the switching field block, to the external peripheral block, and to the control circuit block, the external peripheral block being connected to the control circuit block and to the interconnecting circuit block, and the control circuit block being connected to the switching field block, to the interconnecting circuit block, and to the external peripheral block.

2. A switching apparatus as claimed in claim 1, comprising at most four switching field blocks, at most four interconnecting circuit blocks, at most one external peripheral block, and one control circuit block.

3. A switching apparatus as claimed in claims 1 or 2, in which the switching field in the or each switching field block has 1 28 inputs and 64 outputs.

4. A switching apparatus as claimed in any one of the preceding claims, in which the interconnecting circuit block comprises at most 1 28 + 32 signal transmitter/receivers.

5. A switching apparatus as claimed in any of claims 1 to 4, in which an output of the peripheral interface unit of the control circuit block is connected to a test device and/or a check device.

6. A switching system comprising a plurality of switching apparatuses, each as claimed in claim 1, and each including a control circuit block with a peripheral interface unit having an output connected via a bus system to at most two switching field blocks, at most four interconnecting circuit blocks and one external peripheral block.

7. A switching system as claimed in claim 6, in which the switching field of each switching field block is provided with 256 inputs and 128 outputs and/or 128 inputs and 120 outputs.

8. A switching system as claimed in claim 6 or 7, the peripheral interface units of the control circuit blocks in the switching apparatuses have further outputs connected to a first output of a peripheral unit of a single separate unit whose other output is connected to a test device and/or a check device.

9. A switching apparatus substantially as hereinbefore described with reference to and as illustrated in Fig. 1 or 2 of the accompanying drawings.

1 0. A switching system substantially as hereinbefore described with reference to and as illustrated in Fig. 3 of the accompanying drawings.