The present invention includes a method of eliminating interference from an undersettled electrical signal, the undersettled electrical signal including a test signal at a known frequency. One embodiment of the present invention includes a method comprising the steps of providing a digitized version of the undersettled electrical signal (at 46); generating a frequency spectrum of the digitized version of the undersettled electrical signal (at 56); spectrally interpolating the frequency spectrum to generate an interference signal frequency spectrum (at 65); and subtracting the interference signal frequency spectrum (at 65) from the undersettled signal frequency spectrum (at 56) generating a settled signal spectrum (at 75). Another embodiment of the present invention includes a system comprising means (40 or 45) responsive to the undersettled electrical signal for producing a digitized version of the undersettled electrical signal (at 46); means (50) responsive to the digitized version of the undersettled signal for transforming the digitized version of the undersettled signal into a transformed signal; and means (60 and 70) including a spectral interpolator (60) responsive to the transformed signal for removing interference from the transformed signal generating a settled signal output (at 75).