Abstract: The present invention discloses a method for symbol synchronisation in high speed optical orthogonal frequency division multiplexing (OOFDM) transmission systems via coding the electrical OFDM symbols by adding an independent low power-level alignment signal, converting the encoded signal into the optical domain for transmission, and in the receiver converting the received optical signal to the electrical domain and digitally processing to detect the symbol alignment offset by utilising the independent low-power level alignment signal. The present invention is suitable for point-to-point and point-to-multi-point OOFDM networks and has the additional features of timeslot and frame alignment, compensation for receiver sampling clock offset and providing physical layer network security. The superimposed training signal is a DC offset whose value varies at symbol transitions.

Abstract: The present invention discloses a method for achieving optimised synchronous clock distribution of point-to-multipoint optical orthogonal frequency division multiplexed networks such that bandwidth sharing in both the time and frequency domain is possible without interference between users. The invention details how all clocked components in the network are synchronised such that no clock offset compensation is required anywhere in the network. Also the present invention discloses a method for optimisation of the synchronous clocking method to maximise the system bit error rate (BER) performance, furthermore the present invention discloses a method for implementing multiband-OOFDM where ONUs can easily select any OOFDM band for data reception providing network configuration flexibility.

Abstract: A method of providing a user controllable sign, on the trailer of a tractor-trailer rig. The tractor includes a cab and the trailer is electrically connected to the tractor by way of a jack that provides a set number of electrical connections between the tractor and the trailer. The method begins with the installation of a manual input device in the cab. This device creates a signal that can be overlaid on a jack input without disrupting the input and is electrically connected to a jack input. Also, a signal receiving unit is installed in the trailer, and is connected to a wire electrically connected to the jack input that receives the user signal from the manual input device. This unit is able to determine the presence of the signal from the manual input device. Also installed in the trailer, is a sign deployment controller that is at least in part responsive to the user signal receiving unit. Finally, a sign assembly, controlled by the sign deployment controller, is installed.