Online instantaneous frequency estimation utilizing empirical mode decomposition and hermite splines

Most of the available frequency estimation methods are restricted for the application to signals without a bias or a carrier signal. For offline analysis of a signal an existing carrier may be determined and eliminated. However, in the case of online computations the carrier is not accurately known a priori in general. An error in the carrier signal directly affects the accuracy of the subsequent instantaneous frequency estimation approach. This article focusses on the online instantaneous frequency estimation of non-stationary signals based on the empirical mode decomposition scheme. Especially Hermite spline interpolation of samples for empirical mode decomposition is addressed. Hermite splines enables the definition of enhanced boundary conditions and leads to an effective online instantaneous frequency estimation approach. Throughout the article algorithmic details are examined by a theoretical example.