The present invention relates to nonlinear signal processing, and, in particular, to adaptive nonlinear filtering of real-, complex-, and vector-valued signals utilizing analog Nonlinear Differential Limiters (NDLs), and to adaptive real-time signal conditioning, processing, analysis, quantification, comparison, and control. More generally, this invention relates to methods, processes and apparatus for real-time measuring and analysis of variables, and to generic measurement systems and processes. This invention also relates to methods and corresponding apparatus for measuring which extend to different applications and provide results other than instantaneous values of variables. The invention further relates to post-processing analysis of measured variables and to statistical analysis. The NDL-based filtering method and apparatus enable improvements in the overall properties of electronic devices including, but not limited to, improvements in performance, reduction in size, weight, cost, and power consumption, and, in particular for wireless devices, NDLs enable improvements in spectrum usage efficiency.

A digital filter circuit includes retrieve stream data as a digital signal, and cyclically operate a first phase and a second phase. The circuit includes a short-term storage unit configured to store a local state variable, a long-term storage unit configured to store a global state variable, a first phase synthesizing unit that outputs the digital signal in the first phase under an influence of the local state variable stored in the short-term storage unit, and a second phase synthesizing unit that outputs the digital signal in the second phase under an influence of the global state variable stored in the long-term storage unit, where an output from the first phase synthesizing unit and an output from the second phase synthesizing unit are caused to generate an interference due to a phase shift.

A method for determining a finite impulse response filter, including generation of a plurality of individuals presenting configuration parameters, and cyclic implementation of the following operations in relation to each current population of configuration parameters: evaluation by an objective function of each individual, evaluation by at least one constraint function of each individual, selection of a group of individuals among all the individuals based on their evaluations by the objective function and the constraint function and formation of parent individuals, crossover of parent individuals to form a new population, mutation of individuals in the new population, and verification of a stopping criterion.

A digital filter circuit includes retrieve stream data as a digital signal, and cyclically operate a first phase and a second phase. The circuit includes a short-term storage unit configured to store a local state variable, a long-term storage unit configured to store a global state variable, a first phase synthesizing unit that outputs the digital signal in the first phase under an influence of the local state variable stored in the short-term storage unit, and a second phase synthesizing unit that outputs the digital signal in the second phase under an influence of the global state variable stored in the long-term storage unit, where an output from the first phase synthesizing unit and an output from the second phase synthesizing unit are caused to generate an interference due to a phase shift.