ON THE LOCAL FREQUENCY, GROUP SHIFT, AND CROSS-TERMS IN SOME MULTIDIMENSIONAL TIME-FREQUENCY DISTRIBUTIONS - A METHOD FOR MULTIDIMENSIONAL TIME-FREQUENCY ANALYSIS

This correspondence presents an analysis of the representation of loca l frequency and group shift using multidimensional time frequency dist ributions. In the second part of the correspondence, we extend the ana lysis to the multicomponent signals and cross-terms effects. On the ba sis of that analysis, an efficient method, derived from the analysis o f the multidimensional Wigner distribution defined in the frequency do main, is proposed. This method provides some substantial advantages ov er the Wigner distribution: the well known cross-terms' effects are re duced or completely removed; the oversampling of signals is shown to b e unnecessary; and the computation time can be significantly reduced, as well. The theory is illustrated by a two-dimensional numerical exam ple.