Siemens Aktiengesellschaft

Eberhard Knorpp

Frithjof Von Sichart

Reiner Binz

Karl-Anton Lutz

Silvian Schaffer

Karl A Lutz

In a time-division multiplex switching network unit for time-space switching which operates employing an information memory which has information input thereto in a cyclic manner and read therefrom in a random fashion, the number of terminals is limited, in particular, by the fact that during random output it is not possible to exceed a specific speed. Higher number of terminals are achieved in that the switching network units are composed of modules whose corresponding inputs are connected to one another and into which, during each pulse frame, more PCM words are input than are output. In this manner, the reading frequency is kept low, although, because of the multiple connection at the input end, blocking-free switch-through is provided.

Time division multiplex switching network unit

In switching network units which operate employing an information memory featuring cyclic input and random reading, the number of connections is particularly limited by the fact that during random reading it is not possible to exceed a specific speed. They are normally designed in such a manner that, to a full extent, they can effect both time-wise switching and spatial switching. In these units, the speed restriction during random reading means that the number of connections normally cannot exceed a certain value. Moreover, the facility of time channel conversion to a full extent in units of central switching stages represents an unnecessary expense. Such units are therefore constructed from a plurality of identical modules whose equivalent inputs are connected to one another and into which, during each pulse frame, more PCM words are input than PCM words are stored therein or can be read in random therefrom. Therefore, the time shifts which can be achieved serve primarily for purposes of spatial assignment, although the expense in comparison to the full time-spatial switching units is lower and a larger number of incoming lines can be connected without exceeding the permissible reading speeds.

A time-division multiplex switching network is constructed of units designed as time stages which operate blocking-free and which are multiply divided. A plurality of units of identical structure to a plurality of switching units of a switching network portion is assigned to each switching network portion, the plurality of units being operated as multiplexers at which the outgoing time-division multiplex lines are connected and whose normally non-utilized outputs can be connected by way of switches to other time-division multiplex lines extending from other switching network portions. Upon failure of the latter switching network portions, the switches are closed for rerouting the traffic through the system.

Time-division multiplex switching network

A method and apparatus for transmitting digital data between subscriber stations and a subscriber concentrator and using time hybrids are described. The two-wire lines connecting the subscriber stations to a concentrator are utilized on a four-wire basis, and operate on a time interleaved manner of actuating the send and receive modes of operation of the time hybrids. The send mode of the time hybrid at the subscriber concentrator is actuated responsive to a synchronizing pulse from the concentrator. The send mode of the time hybrid associated with the subscriber stations occurs upon acceptance of data over the two-wire line and a specific time relationship is established between the received data and the initiation of the send mode. In both types of time hybrids a receive pause occurs between the send mode and the subsequent receive mode, and the pause is of a duration corresponding to the anticipated maximum transit time over the two-wire line. In the time hybrids allocated to the subscriber stations a send pause is placed between receive mode and subsequent send mode which in its leading portions corresponds in time with the receive pause of the time hybrid in the concentrator.

Method and apparatus for digital data transmission

A method for transmitting digital data in a time-division multiplex telecommunications network over subscriber lines connecting digital subscriber stations to a subscriber concentrator is described. Transfers of data occur over two wire subscriber lines in both transmission directions in a time interleaved manner alternatively and in the form of bits. The bits are formed to have a duration such that in conjunction with the distance/velocity lags of transmission over subscriber lines they almost completely use the sampling intervals or pluralities thereof. This forms the basis for transmisson over time division multiplex paths going out from the subscriber concentrator and coming in thereat, except for a tolerance time interval allowed for the period of the clock generators determining the bit rate in the subscriber sets relative to the period of the exchange clock generator determining the exchange clock rate in the exchange connected to the subscriber concentrator.

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Gauting, Germany

Eberhard Knorpp