GB1527117A - Device for switching synchronous data channels on a time division basis without blocking - Google Patents

Abstract

1527117 TDM data exchange systems DE STAAT DER NEDERLANDEN TE DEZEN VERTEGENWOORDIGD DOOR DE DIRECTEUR GENERAAL DER POSTERIJEN TELEGRAPHIE EN TELEFONIE 9 Sept 1975 [13 Sept 1974] 36973/75 Heading H4K In a TDM data exchange system, different data rates are accommodated by allocating a plurality of time channels per frame to each subscriber, the number of channels depending on the particular data rate, and the addressing of a time slot interchange store for effecting connections between the channels allocated to two subscribers in communication is arranged such that the plurality of channels allocated to a single subscriber is represented by a single address whereby the information arriving in said plurality of channels is switched via the same location of the slot interchange store i.e. each location of the interchange store is individual to a respective subscriber. Data from individual subscribers is multiplexed on to 80 channel highways 13, each subscriber being allocated.particular channels on a highway on a semipermanent basis, the allocation being stored in a conversion store 35 which has one location for each time channel incoming to the exchange, i.e. one for each of the 256 x 80 channels incoming on 256, 80 channel highways 13. Subscribers are allocated one, four, sixteen or eighty channels per frame according to their data rates, i.e. 750 b/S to 60 Kb/S, and these allocations can be changed using a teleprinter at the exchange to modify the information in the conversion store 35. A connection store 27 and a slot interchange store 26 are then addressed using subscriber addresses as opposed to the channel addresses used in a standard arrangement (Fig. 5, not shown). Hence in each time interval of the exchange switching frame a highway address as given by a count to 256 binary counter 23 and an incoming highway channel address as given by units 16, 19 (the unit 16 deriving the channel addresses for a respective highway from the sync. information or the highway) are used in combination to address the conversion store 35 to determine the subscriber address which is used to feed the information in the corresponding time channel into a location of interchange store 26. For read out a similar operation is used except that the subscriber address from conversion store 35 is used to address connection store 27 to determine which location of store 26 should be read out to the channel of the particular subscriber. There is described with respect to Fig. 8 (not shown) the processor used for completing connections between subscribers and the method by which such connections are completed. In addition to the stores 35, 26, 27 a further subscriber store (43) is provided which stores in respect of each subscriber his connection status, e.g. free, calling, busy, out of service &c., and this store is addressed via conversion store 35 in a similar manner to stores 26, 27.