A coin-validation arrangement in which a wavelet analysis is used to derive accurate information from signals related to coin sensors placed in the path of an input coin, this information being compared with corresponding information relating to sample coins, the result of the comparison giving rise to a "pass/fail" validation decision on the input coin. The information may be derived from a sampling of the sensor-related signal, a measurement of signal amplitudes for each point and a correlation of each amplitude with the corresponding amplitude of one or more preselected wavelets to provide a set of correlation coefficients. In an alternative embodiment the sampled sensor-related signal is subjected to a discrete wavelet transform operation using high-and low-pass filtering and subsequent subsampling stages, thereby producing a set of DWT coefficients. In either case the number of coefficients used in the comparison process may be reduced, thereby saving processing power.