System for controlling and shaping the spectrum and redundancy of signal-point limited transmission

A method of spectrally shaping source samples to transmitted samples based on a set of predetermined characteristics of a frequency spectrum, wherein the allowable signal levels of the transmitted samples are limited to a prescribed set, and wherein the source samples are partitioned into data frames, said method comprising the steps of:

• (a) calculating, for a current data frame and a predetermined number of additional data frames, a Running Filter Sum of unwanted signal levels, wherein said Running Filter Sum is based on a biquad filter;
• (b) computing an objective function in accordance with the Running Filter Sum obtained in Step (a);
• and
• (c) selecting, for the current data frame of source samples, at least one redundant sign for optimization of the objective function computed in Step (b).

A system for controlling and shaping transmitted data samples having predetermined frequency characteristics and allowable transmit signal levels, wherein the transmitted samples are partitioned into data frames, said system comprising:

• a microprocessor configured to:
• (a) calculate, for a current data frame and a predetermined number of additional data frames, a Running Filter Sum to obtain a measure of unwanted signal components of source samples up to at least the current block, wherein said Running Filter Sum is based on a biquad filter;
• (b) compute an objective function based on the Running Filter Sum;
• (c) select, for the current data frame of source samples, at least one redundant sign to optimize the objective function;
• and
• a semiconductor memory device for storing and enabling the microprocessor to access the Running Filter Sum, the objective function, and the redundant sample.

A method of spectrally shaping transmitted samples with a set of predetermined frequency characteristics and a predetermined set of allowable transmitted signal levels, wherein each of said transmitted samples comprises an amplitude and a sign, and wherein said transmitted samples are transmitted in data frames corresponding to groups of input data bits, and wherein each of said data frames is divided into at least one spectral shaping frame, said method comprising the steps of:

• (a) partitioning each of said groups of input data bits into:
• a first subgroup used to select the amplitudes of said transmitted samples in said data frame;
• and
• a second subgroup used to select a sign-combination subset for each of said spectral shaping frames in said data frame, wherein said sign-combination subsets comprise sign combinations which differ from each other by more than one sign bit;
• (b) calculating, for each of said transmitted samples, a Running Filter Sum of unwanted components up to at least the current spectral shaping frame for at least two of said sign combinations in said sign-combination subset, wherein said Running Filter Sum is based on a biquad filter;
• (c) computing an objective function in accordance with said Running Filter Sum obtained in step (b);
• (d) selecting, for each of said spectral shaping frames of transmitted samples, a sign combination from said sign-combination subset such that said objective function of step (c) is optimized.