Abstract: In a method of allocating time slots for transmission in a half-duplex time division multiple access point-to-multipoint bidirectional transmission system enabling transmission between a central station and a plurality of remote stations at least one time slot is allocated to each remote station and to each transmission direction. The set of all time slots used for transmission from the central station to the remote stations are grouped into downward frames and the set of all time slots used for transmission from the remote stations to the central station are grouped together in upward frames. The origin time of the upward frame is chosen in each remote station so that in the central station the origin time of the frame is separated from the end time of downward frames by a period less than twice the transmission time between the remote station and the central station, whereby there is defined in the remote station an overlap area between upward and downward frames.

Abstract: A method for determining the transmission time between remote terminal stations and a central terminal station in a point-to-multipoint bidirectional transmission network. The central station measures the time interval between a reference time for sending of information signals by the central station and reception by the central station of a location signal sent by a remote station after a time-delay starting from a reference time for reception of information signals by the remote station so that the location signal is received by the central station in a predetermined location window not assigned to reception of information signals by the central station. For a given remote station the time-delay is variable from an initial value such that the location signal is not necessarily received in the window and the location signal sending by the remote station is then repeated until the location signal is received by the central station in the window.

Abstract: A method of reinforcing structures by means of tensioned steel cables is disclosed. A hollow conduit or duct is positioned in the structure and secured therein and made a part thereof by pouring concrete in a form surrounding the conduit. A specified number of steel strands, wires or cables are inserted and pushed through the conduit one-by-one by a mechanical strand pusher. A nose guide is positioned on the end of each of the strands if required to enable them to pass easily through the conduit. When the required amount of strands are positioned in the conduit and the concrete has set to a predetermined strength, the strands are stressed thereby putting the structure under compression.