The display-equalized filter for frequency-time analysis
Douglas C. Nyman, M. Landisman · Bulletin of the Seismological Society of America · 1977
Abstract Frequency-time analysis (FTAN) results are usually presented as an array of amplitude values associated with discrete intervals group velocity and log period. The display-equalized filter, a modified form of the Gaussian frequency-time filter, produces amplitude estimates for which the frequency-time “averaging region” is of approximately constant shape, although varying in size, throughout the display. The shape of the averaging region can be adjusted to permit greater frequency resolution, with a corresponding loss of time resolution, and vice versa. An improved time-variable filter effectively utilizes the optimum frequency-time resolution of the Gaussian filter.