Multilevel encoder

An encoder for providing a multilevel encoded signal comprising:

• a device for presenting a plurality of information bits in parallel format;
• a symbol selector having a plurality of inputs and an output, the symbol selector being configured to output a symbol that is defined by a signal constellation, whereby the symbol is defined by a magnitude and phase that are uniquely associated with a state of the plurality of inputs;
• a first encoder having an input and an output, the input of the first encoder being associated with at least one of the outputs of the device and the output being associated with at least one of the inputs of the symbol selector, the first encoder being defined by a code, wherein the first encoder is configured to generate an output that defines a four-way set partition of the signal constellation;
• and
• a second encoder having an input and an output, the input of the second encoder being associated with at least one of the outputs of the device and the output being associated with at least one of the inputs of the symbol selector, the second encoder being defined by a code, wherein the second encoder is configured to generate an output that defines a two-way set partition of the signal constellation.