ata transfer rate for the current line conditions. DMT allocates bits and transmission power away from the induced noise. The advantages of this process are an optimized data rate and less interference with other services existing in the same sheath, due to the symmetrical nature of induced crosstalk. The DMT technique exhibits a high degree of spectral compatibility based on power spectral density, rather than absolute transmit power. DMT has a substantial advantage over single carrier modulation systems in the presence of impulse noise. DMT spreads impulses over a large number of bits, averaging peaks. Only if the average exceeds the margin does DMT produce an error -- single carrier systems will error every time a peak exceeds the margin. DWMT Discrete wavelet multitone (DWMT) technology increases the usable capacity of telephone wires and coaxial cable, allowing telephone companies and cable operators to deliver two-way broadband telecommunications services over their existing networks. DWMT uses Multicarrier Modulation. A multicarrier system uses a transmission band efficiently by dividing it into hundreds of sub channels that are totally independent and spectrally isolated. In practice, implementations of multicarrier systems use orthogonal digital transformations on blocks of data, a process called subchannelization, in an attempt to achieve the frequency partitioning shown in the figure below. By keeping the signal sub channel power contained in a narrow bandwidth, each sub channel occupies only a small fraction of the total transmission band and overlaps only with immediately adjacent sub channels. When a signal is transmitted over a long copper loop (e.g. several miles), the higher frequency components of the signal attenuate significantly more (tens of dB) than the lower frequency components. Narrowband interferers from AM or amateur radio signals also affect the transmission by destroying the signal in parts of the band. Mul...
