Abstract: The present invention includes a power cable tension control device having at one end an adapter capable of insertion into a computer port and at the opposing end a cable retaining structure for retaining a power cable, such as an AC power cable. The adapter does not electrically communicate with the retained power cable and therefore does not act as a conduit through which the power cable electrically communicates with the computer. The computer cable communicates with the computer using a port away from the adapter. Thus, the present invention provides a device that further anchors the power cable to the computer thereby reducing strain on the plug region of the power cable or the computer port, which prolongs the life of the power cable or computer port.

Abstract: A digital signal is used for railway track circuit signalling. A digital signal comprises a pseudo-random binary sequence selected from a set of such sequences. The set is chosen to give the lowest possible cross-correlation between different sequences, to minimize the risk of false identification. Gold codes are suitable. One of the sequences indicates the absence of a train from the track section and this code is generated until an indication is given by a train detector that a train is present. Generation of the train absence signal is then inhibited, and other sequences are generated providing information to the train. The generated sequences are received and coded in a fail-safe decoder.