Patent ID: 8320233

Claim:
A system comprising: a first network device including a first receiver and a first transmitter that operate in a frequency band from 1 kHz to 600 kHz, wherein the first transmitter includes: an encoding module including an interleaver, wherein the interleaver: operates in a plurality of modes including a first mode and a second mode, performs repetitive encoding on transmit data when placed in the second mode, and implements an interleaving pattern by generating an interleaved bit position (I,J) from an original bit position (i,j), where I=(a*i+b*j)% m and J=(c*j+d*I)% n, and where i, j, m, n, a, b, c and d are integers; and a modulation module in communication with the encoding module, the modulation module including: an adaptive tone mapping module to modulate an output of the encoding module to selected orthogonal tones located in the frequency band based on a tone map; and a frequency pre-emphasis module to pre-emphasize at least one of the selected orthogonal tones to compensate for attenuation during propagation of a transmitted signal; a transformer connected by a first power line to the first network device; and a second network device connected by a second power line to the transformer, wherein the second network device comprises a second transmitter and a second receiver, and wherein the second receiver selectively adjusts the tone map based on the transmitted signal received by the second receiver.