Signal Processing and Analysis Techniques from the Folklore

A number of well-known and frequently applied signal analysis and processing methods do not appear to be documented in the signal theory literature. While they are useful and widely used, these methods often do not involve the levels of innovation or theoretical descriptions that normally justify publication in signal processing journals, and their applications may be too narrow for inclusion in textbooks. Several lesser-known of these methods are described: (1) two-stage tuning; (2) cyclic frequency shifting; (3) frequency smoothing using the Lank-Reed-Pollon algorithm; (4) detecting "persistence;" (5) raising an analytic signal to non-integral powers; (6) adaptive notch filtering; and (7) noise-level estimation.