The testing systems of Rayleigh wave both in steady-state and transient-state and the calculating principle of dispersion curves of phase velocity of Rayleigh wave are simply described first. Then
the theoretic presupposition
on which the dispersion curve from SASW method may be equivalent with the result from steady-state method
is pointed out. An optimized coherence-function method
by which the testing effect of SASW method can be improved by means of testing procedure control