Digital spectra of non-uniformly sampled signals: theories and applications. I. Fundamentals and high speed waveform digitizers

The author derives a digital spectral representation of a nonuniformly sampled signal. He presents a detailed spectrum analysis of a nonuniformly sampled sinusoid, showing that the spectrum comprises uniformly spaced line spectra. In addition, the signal-to-noise ratio is obtained in closed form. The theories are then applied to analyze the harmonic distortion introduced in high-speed waveform digitizers due to time-base errors. The digitizers analyzed are those which utilize interleaving/multiplexing and random equivalent-time sampling techniques to extend their capabilities. Theoretical results are confirmed by the experimental results for an actual waveform digitizer