Method and apparatus for transmitting data from a transmitter device to one or more receiver devices

A transmitter device for transmitting data, using a discrete multi-tone modulation technique, over a plurality of pairs of wires to one or more receiver devices, each of the one or more receiver devices connected to the transmitter device via at least one respective pair of wires, each receiver device being operable to receive signals detected as a change over time in a potential difference across local ends of each respective pair of wires extending between the receiver device and the transmitter device, the transmitter device being operable to transmit signals onto the wires extending between the transmitter device and the one or more receiver devices in a plurality of different modes, over a plurality of different channels, the different modes including phantom and differential modes and the different channels including a first set of phantom channels, the transmitter being further operable to select a second set of phantom channels from the first set, the second set being a subset of the first set comprising some or all of the phantom channels of the first set such that at least some of the phantom channels in the second set are not mutually orthogonal to one another, the transmitter device comprising:

• a connector for connecting the selected phantom channels of the second set of phantom channels to the transmitter device,
• the transmitter device being further operable to transmit signals from the transmitter device onto the phantom channels of the second set of phantom channels, and, in respect of each of a plurality of different tones employed by the transmitter device, to select a tertiary set of phantom channels, each tertiary set of phantom channels being a proper subset of the second set of phantom channels and being selected so as to comprise phantom channels which are mutually orthogonal to each other, the transmitter device being further operable to generate, in a digital frequency domain, a set of signals including at least one signal for each phantom channel in the second set of phantom channels, wherein, for each respective tone, data is encoded into signals for transmission over the phantom channels in the respective tertiary set of phantom channels for that tone and each signal associated with a phantom channel which is not in the respective tertiary subset for any given tone is set to a low-interference-causing value for that tone.