Aliasing problems associated with the implementation of multifrequency test strategies

This paper addresses the problems of aliasing as associated with frequency response analysis. Modern composite frequency response analysers rely on the use of digital memory and digital-to-analogue techniques for the storage and generation of their test waveforms. The application of such techniques, however, results in reconstituted waveforms which are non-band-limited in the frequency domain. If these waveforms are applied directly to the system under test then the system output cannot be guaranteed to be digitally sampled without introducing aliasing effects into the measurement process. The basis for a technique for compensating for the effects of aliasing in such frequency response analysers is presented. This technique is largely based upon a software algorithm, and removes the need for anti-aliasing filters