ABSTRACT
The basic concepts of spectral analysis through Fourier transforms typically are developed for functions on a one-dimensional domain where the independent variable is time. On the other hand, the domain of many geodetic and geophysical signals is the sphere that approximates the Earth, which in some applications may also be approximated locally by a plane. For many geophysical applications, the signals in the spatial domain are not endowed with a fundamental period and the preceding development of Fourier series has perhaps only limited intuitive appeal. The rectangle function is one of the more useful functions in the study of spectral analysis. It will surface repeatedly in the discussion of filters and spectral density estimation, as well in any other application of practical data analysis since observations of a geophysical signal are available only in a limited spatial domain. Geodetic and geophysical data may be collected in one spatial dimension and can certainly be analyzed in that stogle dimension.
