Abstract: A signal processing system according to various aspects of the present invention includes an excursion signal generator, a scaling system and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold and generates a corresponding excursion signal. The scaling system applies a real scale factor to contiguous sets of excursion samples in order to optimize peak-reduction performance. The filter system filters the excursion signal to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from a delayed version of the original signal to reduce the peak. The signal processing system may also control power consumption by adjusting the threshold. The signal processing system may additionally adjust the scale of the excursion signal and/or individual channel signals, such as to meet constraints on channel noise and output spectrum, or to optimize peak reduction.

Abstract: A digital communications transmitter (100) includes a digital linear-and-nonlinear predistortion section (200, 1800, 2800) to compensate for linear and nonlinear distortion introduced by transmitter-analog components (120). A direct-digital-downconversion section (300) generates a complex digital return-data stream (254) from the analog components (120) without introducing quadrature imbalance. A relatively low resolution exhibited by the return-data stream (254) is effectively increased through arithmetic processing. Distortion introduced by an analog-to-digital converter (304) may be compensated using a variety of adaptive techniques. Linear distortion is compensated using adaptive techniques with an equalizer (246) positioned in the forward-data stream (112). Nonlinear distortion is then compensated using adaptive techniques with a plurality of equalizers (226) that filter a plurality of orthogonal, higher-ordered-basis functions (214) generated from the forward-data stream (112).