MULTIFREQUENCY EDDY CURRENT TESTING DEVICE

摘要

ABSTRACTMultifrequency February 9, 1981The prior art of multifrequency eddy current instruments hasrequired a band pass filter to separate each individual frequency. Thedrawback of the above mentioned method is the requirement to change thebandpass filter if the inspection frequency is changed. This inventionrelates to a design that eliminates the requirement for a bandpassfilter. The aggregate of inspection frequencies are applied to linearmultipliers which shift the information from one of the inspectionfrequencies to a base band signal. The information is then separatedfrom the signals of other frequencies with a low pass filter. The advan-tage is that an inspection frequency may be changed by changing theoscillator frequency only.