Robert's recursive frequency filter: A reexamination

Summary The recursive filter designed by Robert (1966) has been investigated in detail. The filter is found to have a dual impact on the wave on which it acts in the sense that it changes the phase and amplitude of the wave unlike a nonrecursive filter which only changes the wave amplitude. The dual nature of the filter's effect is attibuted primarily to its recursive nature. Procedures for choosing the correct value of the smoothing element of the filter for achieving some desired postfiltration results are also discussed.With 4 Figures