A method comprises collecting a data set of field characterization measurements at a location inside a reverberant cavity excited by signals having multiple discrete electromagnetic frequencies; and performing a number (n) of circular shifts on the data set by a frequency step (Δf) and computing a covariance-based coefficient at each shift until the coefficient indicates a lack of correlation. The method further comprises computing a quality factor (Q) of the reverberant cavity as fc/(Δf×n), where fc is center frequency of the data set.