  We present a method of mode analysis to search for signals with frequency
evolution and limited duration in a given data stream. Our method is a natural
expansion of the Fourier analysis, and we can obtain the information about
frequency evolution with high frequency precision and high time resolution.
Applications of this method to the analysis of inspiral and burst signals show
that the signals are characterized by an index which we name `bounce hardness'.
The index corresponds to the growth rate of the signals.
