Signal processing techniques and systems and, in particular, an apparatus, system, algorithm and method of extraction of sinusoidal signals of time-varying nature is described. The apparatus, system, algorithm and method provide for extraction of a specified single sinusoidal component of an input signal, potentially containing other components and noise, and tracking variations of the amplitude, phase and frequency of such a sinusoid component over time. A "tool" or "core unit," embodying the apparatus, system, algorithm or method may be used in isolation or as the fundamental building block of single-core or multi-core systems.