Abstract: In a time-division multiplexing system, data are supplied to the multiplexer with different speeds. Depending on the speed, time slot groups are allocated to the data, with the number of allocated time slots increasing with the speed. The search for groups of free time slots occurs in a fixed sequence. Data to which time slot groups at the end of the fixed sequence have been allocated, are relocated to time slot groups which have become free nearer the beginning of the sequence. The allocated time slot group for the forward transmission direction is signalled to the multiplexer of the remote station which in turn occasions a corresponding allocation of time slots for the reverse transmission direction for data originating at the remote station.

Abstract: A process for testing a data transmission system by which data are transmitted by way of two data transmission links and by way of a first transmission device and a second transmission device provides that a test loop is closed, in dependence upon a loop signal, and a transmission section is tested. Data are transmitted in data blocks and each block includes a status bit, a synchronizing bit and n data bits. The loop signal is formed from a given combination of the status bit and data bits, and at least one of the data bits is inverted before being returned to the second transmission device.

Abstract: This invention relates to an improvement in the process for reconditioning worn frogs of railway switches by severing the frog together with sections of the regulating rails adjacent thereto, reconditioning the frog, and renewed welding-in of the frog block, the improvement comprising severing the worn frog from the junction regulating rails at connecting welds thereof, reconditioning the frog, and welding two new regulating rails onto the reconditioned frog, with compensation for the loss in length, due to the severing operation, simultaneously in one casting by aluminothermic welding.