A novel method for detection of aliased frequency components in FFT-based spectrum analysers and digital oscilloscopes

A new method for detection of aliased frequency components in fast Fourier transform (FFT)-based spectrum analyzers and digital oscilloscopes has been developed. The basic system consists of two analog-to-digital converters (ADCs) working at slightly different sample rates. The frequency components occurring in the resulting spectra are also slightly shifted to each other. By calculating the difference between the two spectra, an aliased frequency component will give a contribution to the difference that a nonaliased component will not.<
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