Abstract: A method and apparatus for performing spectral shaping transmitted samples with a set of predetermined frequency characteristics and a predetermined set of allowable transmitted signal levels are disclosed. The method first calculates, for each of the transmitted samples, a running measure of unwanted components upto the current sample. It then computes, for each block of the transmitted samples, an objective function based on the running measure previously calculated. It then selects, for each block of the transmitted samples, at least one redundant sample to be added or at least one transmitted sample to be modified, at structured or randomized location within the block to optimize the objective function. The location of the dependent sample can further be fixed, scrambled (pseudo random) or randomized. The method of computing can be any one of the following: a Running Filter Sum, a Running Fourier Transform (“RFT”) or Fast FT (“RFFT”), or an RDS, for each transmitted sample.

Abstract: The present invention relates to multiple modulus conversion (MMC) techniques for mapping data in a pulse code modulation (PCM) modem system. In accordance with the present invention, signal point constellations are arranged to receive the output indices generated by the MMC procedure such that the probability of transmission of higher power codewords is relatively low compared to the probability of transmission of lower power codewords, while maintaining the same or larger minimum distance between signal points. In addition, the present invention provides techniques for obtaining the probability of occurrence for each constellation or signal point associated with a given data communication session and for determining the theoretical average transmit power associated with a given set of signal point constellations and MMC parameters.

Abstract: Methods and apparatus are disclosed for shaping and controlling the spectrum of transmitted samples with a set of predetermined frequency characteristics and a predetermined set of allowable transmitted signal levels are disclosed. In particular, methods of minimizing the energy of the signal at unwanted frequencies are described. For each of the transmitted samples, the system computes a running measure of unwanted components. It then computes, for each block (or "data frame") of the transmitted samples, an objective function, for example, a running filter sum based upon a biquad filter function. It then selects, for each block or spectral shaping frame of transmitted samples, a sign combination from a sign-combination subset such that the objective function is optimized.