Step-wise tracking electronic filter with offset up and down transition

摘要

A step-wise tracking electronic filter comprises a parallel bank of a plurality of band pass filters respectively having a plurality of electronic switches and respectively having different band widths, and a command signal generating device generating a command signal from the frequency of a primary alternating electrical signal being transmitted through the step-wise tracking electronic filter and being conditioned thereby or from an auxiliary alternating electrical signal obtained for the sole purpose of generating the command signal therefrom; wherein the command signal closes one of the plurality of electronic switches belonging to one of the plurality of band pass filters having a band width substantially including the frequency of the primary alternating electrical signal and opens the electronic switch when the band width of the band pass filter substantially excludes the frequency of the primary alternating electrical signal in an operating mode wherein only one electronic switch is closed at a time, and the command signal closes the first of two electronic switches respectively belonging to an adjacent pair of the band pass filters and opens the second of the two electronic switches when the frequency of the primary alternating electrical signal is equal to a first value of a transition frequency, and closes the second of the two electronic switches and opens the first of the two electronic switches when the frequency of the primary alternating electronic signal is equal to a second value of the transition frequency offset from the first value of the transition frequency.