Abstract: An electric device (202, 301) for connecting an analogue data transfer device (202) by means of a control unit (203) to a digital transfer system comprises means for connecting to a data transfer device via a twin cable (204). In addition, it comprises a current amplifier arrangement (214, 314, 340) for feeding a certain current to the twin cable, a first current switching device (219) for switching a first control current to the current amplifier arrangement, and a second current switching device (220) for switching a second control current to the current amplifier arrangement. The current switching devices (219, 220) are preferably current mirrors.

Abstract: An arrangement for determining transmission delay in a subscriber network which has a plurality of subscriber sets, a plurality of subscriber terminals (to one subscriber terminals to one subscriber terminal being connected at least one subscriber set by a transmission connection implemented in an electrical form), and a central unit, which is common to the several subscriber terminals and connects the subscriber sets to a public switched telephone network. In the subscriber network, time-division data transmission between the several subscriber terminals and the central unit occurs along a common transmission path. A value representing the transmission delay between the central unit and an individual subscriber terminal is determined, whereby a transmission of a subscriber terminal towards the central unit is synchronized in he subscriber terminal with the frame structure of a signal to be transmitted from the central unit towards the subscriber terminal.

Abstract: A subscriber network arrangement for connecting several subscribers to a telephone network, in which the subscriber network includes (a) several subscriber sets and, (b) several subscriber terminals. To one subscriber terminal is connected at least one subscriber set by use of a transmission connection implemented in an electrical form. The network further includes (c) a central unit common to the several subscriber terminals, whereby a time-division data transmission between the several subscriber terminals and the central unit occurs along a common transmission path. To be able to construct the network at costs as low as possible by utilizing the existing transmission capacity as efficiently as possible, a message transmission channel common to all subscriber terminals of the central unit is formed in the same transmission frame as actual payload data in both transmission directions on the common transmission path between the central unit and the subscriber terminals.