= Solution
Regular timing supplies a common interval and a well-defined <frequency> grid for a standard <discrete Fourier transform> and <Fast Fourier transform>. It also makes sample-index lags correspond to fixed physical delays in <cross-correlation>, <autocorrelation> and digital filtering. These methods estimate <frequency> content and characteristic periods, separate instrument or environmental noise from signals, identify arrivals and time delays, and compare ground-motion spectra.
A uniform interval establishes a <Nyquist frequency>; <frequencies> above it alias unless filtered before acquisition. Interpolating irregular data onto a regular grid does not undo prior <aliasing> or fill large gaps with new measurements, and it can alter spectra and create correlated errors. Methods that directly use irregular times are possible, but the ordinary FFT and fixed-lag filter formulas cannot simply treat the original irregular observations as evenly spaced.
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