D.M. Boore
2003
<p>Phase<span> </span>derivatives<span> can be used to compute instantaneous frequency and envelope delay (also known as group delay). Envelope delay, in the guise of </span>phase<span> differences, has been used by engineers in the </span>simulation<span> of </span>strong<span> </span>ground<span> </span>motion<span>, particularly as a way of controlling the duration of </span>motion<span>. Simulations using the stochastic method, in which duration is a simple function of source duration and a path-dependent duration, possess envelope delay properties similar to those from simulations based on </span>phase<span> differences. Envelope delay provides a way of extending the standard stochastic method to produce nonstationary frequency content, as produced by </span>ground<span> </span>motions<span> containing surface waves.</span></p>
application/pdf
10.1785/0120020196
en
Seismological Society of America
Phase derivatives and simulation of strong ground motions
article