(n.) Geophysics. A step in seismic processing to determine the shape of the wavelet, also known as the embedded wavelet, that would be produced by a wave train impinging upon an interface with a positive reflection coefficient. Wavelets may also be extracted by using a model for the reflections in a seismic trace, such as a synthetic seismogram. A wavelet is generated by deconvolving the trace with the set of reflection coefficients of the synthetic seismogram, a process also known as deterministic wavelet extraction. Wavelets may be extracted without a model for the reflections by generating a power spectrum of the data. By making certain assumptions, such as that the power spectrum contains information about the wavelet (and not the geology) and that the wavelet is of a certain phase (minimum, zero), a wavelet may be generated. This is also called statistical wavelet extraction. A particular processing approach to establishing the embedded wavelet is to compare the processed seismic response with the response measured by a vertical seismic profile (VSP) or generated synthetically through a synthetic seismogram in which the embedded wavelet is known. The wavelet can also be extracted through the auto-correlation of the seismic trace, in which case the phase of the wavelet has to be assumed. See: Synthetic Seismogram, Vertical Seismic Profile