Abstract: In an embodiment an interference cancellation method includes generating, by a first device, a first packet, wherein the first packet comprises a first group of elements, a second group of elements, and user data, the first group of elements being different from the second group of elements and sending, by the first device, the first packet to a second device by using at least one pair of subcarriers, wherein two subcarriers in the at least one pair of subcarriers are symmetrical with respect to a direct current subcarrier, and wherein the first packet is usable by the second device to cancel interference in the user data based on the first group of elements and the second group of elements.

Abstract: A method of locating a fault on an electricity transmission line is disclosed. The transmission line has a known line impedance and is operable to transport electricity at one or more system frequencies. The method comprises using measurements of the current and voltage made on the line at one or more frequencies which are different to the system frequency and the known line impedance (Z) to determine a distance to the fault. The method may include monitoring the voltage and the current on the transmission line at the one or more non-system frequencies, and determining from the presence of signals at a non-system frequency on the transmission line that a fault has occurred.

Abstract: A method of locating a fault on an electricity transmission line is disclosed. The transmission line has a known line impedance and is operable to transport electricity at one or more system frequencies. The method comprises using measurements of the current and voltage made on the line at one or more frequencies which are different to the system frequency and the known line impedance (Z) to determine a distance to the fault. The method may include monitoring the voltage and the current on the transmission line at the one or more non-system frequencies, and determining from the presence of signals at a non-system frequency on the transmission line that a fault has occurred.